Loud Speaker? - Page 1
Forum section: electronics / beginners

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 09:32:44 am
content: Hello i got 2 8 watt 14 ohm 2" speakers and i am wondering if i can increase the max volume (like overcklocking the speaker) with any kind of way ....This may sound crazy but it may be possible i think.Also could i use both speakers as one (by connecting them in parallel or in series ?)

author: c4757p
author_rank: Super Contributor
timestamp: May 28, 2013, 11:16:03 am
content: Increase the voltage they are driven with, obviously. Just like overclocking a CPU, you risk damaging them by running them above rated power.As for series/parallel - have you ever wondered why an orchestra isn't dozens of times louder than a trumpet, or why it has so many damn violins? Sound volume adds logarithmically.

author: Psi
author_rank: Super Contributor
timestamp: May 28, 2013, 11:24:32 am
content: If you put the two 14ohm speakers in parallel you lower the total resistance to 7ohms.The amplifier will then put more power into the speaker for the same position on the volume knob.But be aware that you're pushing the amplifier harder in order to get more volume out of it.Depending on the specs of the amplifier you could damage it with low ohm speaker loads.In reality i doubt you'd damage it with 7 ohms since 8 ohms is very common for speakers.A typical amplifier might get unstable in the 1-4ohms range for example.Are you sure your speaker is 14 ohms 8 watts? The reverse (8 ohms and 14 watts) would seem more likely?

author: madires
author_rank: Super Contributor
timestamp: May 28, 2013, 01:33:07 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 09:32:44 amOverdriving speakers isn't a good idea, because at high power levels the sound becomes really distorted. I wouldn't even max out the specified power.QuoteYes, but you have to take care that the amp is able to drive the resulting impedance. BTW, adding up the dB values of both speakers is done by: sq(SPL1² + SPL2²).

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 03:16:51 pm
content: Quote from: Psi on May 28, 2013, 11:24:32 amIts a low power amp LM386 but i think that i will take the speakers

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 03:19:19 pm
content: Quote from: madires on May 28, 2013, 01:33:07 pmThanks but i am already getting distortion from the amp alone (i got a 10 uf cap but the version 2 i am going to build a case and things i am going to put switches so i can sellect value of the cap and ill even put a wire (no cap) to get maximun gain)

author: madires
author_rank: Super Contributor
timestamp: May 28, 2013, 03:42:42 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 03:19:19 pmLet's see. LM386 delivers 700mW at 8 ohms with 9V and a THD of 10%. You won't overdrive the speakers with that :-) But yes. the distortion is awful. I would recommend something like a TDA1519B (2*6W or 12W, roughly 12V). It also got a THD of 10% at maximum power, but if you keep the power below 3W or so you'll have just about 0.1%.

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 04:06:37 pm
content: It doesn't matter how big the speakers are if your audio amplifier doesn't have the power to drive them. LM386 is too small.Make your own amp with TDA2040 or TDA2050 for example, they're mono audio amplifier chips so you need two , one for each channel ...tda2040:http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1460.pdftda2050:http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1461.pdfThe datasheets have examples for both split power supply (if you have transformers with center tap or two separate secondary windings) or for single power supply (if you want for example to power one from a computer power supply or something like that) and they're very easy to make even on breadboard.tda2040 can work with 5v to 40v but at 12v it can only do about 2-3 watts. At about 30v it can do 10w on 8 ohm, or about 18w on 4 ohm with 0.5% distortiontda2050 can work with 9v to 50v but at 12v it can only do about 2.5 watts. At about 40v it can do 22w on 8 ohm with 0.5% distortionTayda electronics has tda2050 on ebay for 3$ for a pair, and the rest of the components are about 3-4$.Here's a page showing one ready made on prototyping board, which uses a split power supply, to see how easy it is:http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 04:28:34 pm
content: Quote from: madires on May 28, 2013, 03:42:42 pmThanks ill probably have to change my amp

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 04:29:50 pm
content: Quote from: mariush on May 28, 2013, 04:06:37 pmThank you but there is a thing.With the LM386 you can use different values of caps for maximun of minimun gain can you do that with the TDA'sAnd also i think that the TDA chips produce much heat.

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 04:58:04 pm
content: Of course you can adjust the gain with those TDA chips, the datasheets explain what each capacitor and resistor in the example circuits do and what increasing or decreasing their values does.Of course these chips will get warm or hot without a heatsink, they're not 100% efficient, they're class AB amplifier chips, not class D chips (but class D chips are more expensive and can be much more difficult to make on your own, these are super easy to use). Their efficiency is about 65-70%, so if you'll give them 40v and output 20-25w to the speakers, you'll get about 10-15w wasted as heat, so you'll need a large heatsink for them.But if you power them from 12v and they output 2.5-4 watts, a small heatsink would be enough, something recycled from an old power supply, or even some metal sheet screwed to the back of the chip may be enough.Your LM386 may not get hot, but that's only because it won't output much power anyway, it's limited to 1.5w or something like that, you only get about 0.7 watts on a speaker... if it doesn't take much power in and doesn't put much power out, what's there to heat?It's not a powerful audio amplifier and no matter how you put it, it's just not designed for those big speakers. Honestly, I wouldn't use it to power something bigger than headphones.The point is that it's a very easy project to tackle, it doesn't cost much money, these chips are very generic and you may find them in stores around you (stores that sell parts for tvs and radios, maybe even people repairing tvs have them around if you ask them), they're cheap. The capacitors and resistors are also cheap...You can find everything needed on eBay if you don't find in Greece, it's really not a problem.It would be a nice simple project for you to make and enjoy.I have an audio amplifier board taken out of an older Phillips TV (I'm attaching it to this message) that uses TDA2040 and never had to adjust the gain, I found that adjusting the volume in Windows was enough. Nowadays I have a 5.1 system and don't use it anymore. The circuit in the datasheets is much simpler, this one has headphone output and some other additions that I don't use and you wouldn't need anyway.The heatsink is sized so that the amplifier would output up to 20-25w per channel, the 35w printed on the board is peak, with 10% distortion. tda2040 is designed for about 40v input voltage, the transformer in the picture is +/- 15v and low current. When I used it with two 10w 4w speakers, the heatsink barely got warm, even at high volume.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 05:01:02 pm
content: Nevermind i saw the datasheet and the site in depth and i saw that instead of a capacitor the TDA uses a resistor

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 05:12:48 pm
content: I think i am going with the TDA 2050 because of its output power.Ill feed a 12 volt DC voltage to it and reffering to the diagram it says that with about 12 volt input voltage the power output is about 10 watts.Also i will use the same gain configuration that i wanted to used with the LM386its a double pole single throw switch the one pole is connected to an led (to indicate the status of the gain) and the other pole to the main capacitor (in this case resistor)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 05:21:31 pm
content: From the datasheet i got this info.I will operate it at 12 voltsAt this voltage the output power is about 10 wattsthe distortion at 20 watts (1 khz) is 0.03%and at 15khz is 1% (non existant at 10 watt)also the power dissipation at 10 watt is also 10 watt (i hope i am wrong at this one)

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 05:42:16 pm
content: No.Pay attention to what the graphs say:The graph is for SPLIT POWER SUPPLY (a power supply that has negative AND positive voltages feeding the amplifier).The voltage values below are listed as +/- VOLTAGE.In the first picture (on the left), you're not interested in 10% distortion, so you look at the second curve that's a bit lower than the first, which is for 0.5% distortion.On the Y axis, you have the output power, on the X axis you have the input voltage, in +/-V. If you're going to use a single power supply ( just ground and +v), you have to double that value.You can see that it crosses the 5w output at +/-10v, so you'd need+20vto get 5w output on the speaker. With 40v (+/-20v) you get about 20w output.With just 12v, you have to look at +/-6v , so you're somewhere between +/-5 and +/-10v, at about 2-3 watts. This is stillway betterthan about 0.5-0.7w you get with LM386, with 10% distortion.Since these have such large input voltage range (up to +/- 25v or 45-50v for single power supply) it makes them great to use with recycled transformers - 24-30v AC transformers are relatively easy to find (but remember it's not just the volts with a transformer, the VA rating must be big enough, let's say about 40-60VA at least, this would make it a heavy transformer, about 0.5 Kg at least).Until you do find one, you can simply use a 12v from a computer power supply and only get a lower number of watts.In the second picture, on the right, you have the Distortion versus output power, WHEN the IC is powered from +/- 22v (so with a single power supply that would be 44v - the IC tolerates a maximum of +/-25v or 50v). This is close to the IDEAL way the amplifier would like to work, the maximum voltage it supports.That one says that with 8 ohm speakers, the distortions are typically below 0.1% from 1kHz to 15kHz.But the graph is only correct for +/-22v or about 44v. If you power the amplifier from only 12v, the distortions may be a bit higher... but should be below 0.5% as the graph in the first picture say.Later edit:The graph there on the left is for8 ohm speakers. If you use 4 ohm speakers, the output power changes a bit, and you can see that in Figure 8, on the following page in the datasheet. And notice that with 4 ohm speakers, the amplifier is no longer able to work at up to +/-25v (50v), the graphs stop at about +/-22v (44v) and on the right side of the page, you see those distortion graphs made for +/-18v (36v) , not for +/-22v like before.

author: madires
author_rank: Super Contributor
timestamp: May 28, 2013, 06:03:32 pm
content: If the supply voltage is 12V single rail the TDA1519B (in BTL mode) would give more power at a THD of 0.5% and you won't need the large cap at the output to block DC. There are also some more powerful amps in that family like the TDA1518BQ with 24W in BTL mode (or 2 * 12W in stereo mode). For single rail applications a car stereo amp is mostly the better solution. The TDA20xx is great if you got a dual rail supply like in a standard stereo.

author: SeanB
author_rank: Super Contributor
timestamp: May 28, 2013, 06:52:34 pm
content: All I did with mine was to use a TDA2009 on a premade board sold as a replacement for some rather unreliable STK modules in older television sets. Added a big heatsink and it runs nicely on 32V from an old inkjet printer power supply.

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 06:53:35 pm
content: madires, the IC is interesting but... if you dig deep in the datasheets you'll notice that it can typically do 10w at 8 ohm with about 14.4v input voltage,in BTL mode.At 12v, it will pretty much go down to about 7-8w at 8 ohm, again, in BTL mode. With just one speaker per channel, it will be about 3.5-4w, just a watt or a couple of watts above the tda20xx.Chris is a beginner at electronics, so he won't easily understand the concept of BTL and doesn't have such nicely made application circuits and examples of pcb and a website showing off a ready made amplifier to get insipiration from, and in addition he only has two speakers right now. He doesn't have four speakers, to put 2 speakers on each channel (which is needed for btl mode).In addition, these ICs will only work at up to about 18v, while the TDA2050 works up to 50v - he can compromise now going for tda2050 and get only 2-3 watts on each channel running it from 12v and later when he finds a transformer with bigger output voltage, he'll get more power. With this tda1519, he'll be stuck at up to 18v and 11-12w in btl mode (or about 6w per speaker).

author: madires
author_rank: Super Contributor
timestamp: May 28, 2013, 07:19:35 pm
content: Quote from: mariush on May 28, 2013, 06:53:35 pmThe decision which TDA fits better is based on the power supply. If it's around 12V the TDA151x is the better choice, if its >16V then the TDA20xx wins. No worries! :-)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 07:29:22 pm
content: Thank you all but i am confused.... i had not so many time to read in depth all the comments but here are some things that will make you life easierMy supply will be a 12 volt 1 amp ac to dc converterI only need 1 channel (left or right ) or even both no prob.I need adjustable gain with caps or resistorsI need it to be loud but no so easily distortedAs for heat dissipation its ok ill use a big ass heatshink or even combine a small heatshink with a fan for maximun cooldown

author: madires
author_rank: Super Contributor
timestamp: May 28, 2013, 07:39:35 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 07:29:22 pmWelcome to the Amp wars :-)QuoteThen it's the TDA1519B. Since you're got a SMPSU please add an additional power filter (a LC filter for example).

author: IanB
author_rank: Super Contributor
timestamp: May 28, 2013, 07:47:36 pm
content: "Adjustable gain" is a "volume control knob". Almost all audio amplifiers need one of these. Typically a logarithmic pot serves this function.The loudness you get with small amplifiers depends mainly on the sensitivity of the speaker. You don't need that much power necessarily for comfortable listening. Small transistor radios have done fine for years with batteries. You will have to test the speakers you have and see how they perform.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 08:02:08 pm
content: Quote from: IanB on May 28, 2013, 07:47:36 pmI am not reffering to the volume knob (sorry for the missunderstanding)I am reffering to the cap between pin 1 and 8 adjusting the value of the cap you actually change the gainhttp://www.ti.com/lit/ds/symlink/lm386.pdf

author: IanB
author_rank: Super Contributor
timestamp: May 28, 2013, 08:23:49 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 08:02:08 pmOK, I see.

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 08:28:27 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 07:29:22 pmOk, Chris, here's a very basic explanation.Amplifiers output a certain amount of power (in watts) based on the resistance of the speakers ( in your case 8 ohms) and the input voltage they receive (and the current, naturally). Some audio amplifiers aren't that sensitive to input voltage, others are.These amplifier chips that I mentioned (tda2040, tda2050) like bigger voltages a lot, the more voltage the more audio power they can output. With these amplifier chips, as you can see in the graph above, the power output increases quite a lot as you increase the input voltage... with +/-5v (10v with single power supply) you only get 2-3 watts, with +/-22v (44v with single power supply) you get 25-30 audio watts (ten times as much).Other amplifier chips like the TDA1519 mentioned by madires only works with a smaller range of voltages and is a bit more efficient with lower voltages, but as a downside it can't give you as much power as the previous chips - it tops out at about 5-6 watts while the tda2050 can do about 20-25 watts.The amplifier chips that can output a lot of power are usually designed to be used with split power supply. That is, you have a transformer with two secondary windings or a single winding with a center tap, and from that you can create a negative voltage and a positive voltage, so they amplifier has two input voltages, like this:From top to bottom, you have at the output +V , GND and -VIn the picture above, you have a transformer that outputs 48V AC with a center tap - the center tap becomes the ground, and there's a positive 24v AC and a negative 24v AC. These are RMS values, so when converted using a bridge rectifier like in the pictures, you get about 34v. So that is a +/- 34v split power supply.The TDA2050 can handle a maximum of +/- 25v so this transformer is actually too big for it, but it's just an example.Split power supply is better for audio amplifier chips because it makes it easier for an audio amplifier to create the audio waves that are sent to the speakers.Single power supply is the power supply like you have on the computer or on ac to dc adapters, where you have just ground and a positive voltage.Some amplifier chips can work with just positive voltage but when using such power supply you have to keep in mind that the voltage difference is now half compared to a split power supply. 12v DC is equivalent to -6 - 0 - +6v split power supply because from -6 to +6 is a potential difference of 12v.So wherever you look in graphs made for split power supplies, you have to look at the values for half the voltage for your single power supply.Now, as the amplifier chip no longer has that positive and negative voltage, the output is harder to generate and it's a bit hard to explain but in such configuration a large capacitor is needed in front of the speaker - if you look in the datasheet for TDA2050 you will see the "single power supply" design has a 1000uF capacitor near the speaker while the split power supply doesn't need one. The TDA1519 works around this issue in BTL mode by making both audio amplifiers in the package work like a single amplifier so in that mode, the audio chip needs two speakers connected for each channel.Going back to your original problem.You have a 12v 1A ac to dc adapter. The power this adapter can deliver to some device is determined by the formula Power = Current x Voltage so the power for this adapter is P = 12v x 1 = 12 watts.An ideal amplifier would take these 12 watts of power and produce 12 watts of audio power.However, you have to understand that audio amplifiers are not ideal, and depending on their type,and they're not very efficient. The amplifier chips we're talking about here are class AB amplifiers, which usually are about 60-70% efficient.But as you can see from that graph I showed you, with 12v input, the amplifier chip can only produce 2-3 watts of audio power without causing a lot of distortion, it just doesn't "like" such low voltages.So you give it 12v, but produces about 3 audio watts. It probably has about 50% efficiency so the tda2050 probably uses about 6 watts out of those 12 watts you make available, the rest are unused. If you make two amplifiers, one for each channel, both chips will use in total 12 watts or more, so your 12v 1A ac to dc adapter is to the limit.I originally told you about 12v because computer power supplies have 12v, so it would be easy to get a used power supply from a computer or just power the audio amplifier from your computer.But keep in mind, even if you connect it to a power supply that outputs 12v and may output 20-30 A on 12v (250-400w), the audio amplifier chips won't use this power, because they don't like such low voltages, they'll still only use about 6-10 watts.The beauty of these chips is that you use properly rated capacitors (with big voltage rating) you can power these audio chips from 12v and get only 3 audio watts in speakers and when you find a transformer you can replace the 12v with the output of that transformer and get lots of audio watts.For example, let's say you find somewhere a 24v AC rms transformer rated for 50 VA (a new one costs about 15-20$, on eBay they're cheaper but shipping to Greece costs anyway money). When converted to DC, that 24v AC rms becomes about 32 volts. The total power of the transformer is 50VA, you can equal that to 50 watts.If you go and look on that graph, 32V DC from a single power supply is equal to about +/- 16 V so the TDA2050 could produce about 13-14 audio watts in the speaker. Now keep in mind the amplifier chip is about 60-70% efficient, so to produce those 13-14w of audio power, the amplifier "eats" about 4-6 watts and wastes it as heat, so in total the amplifier chip uses about 20w out of those 50w the transformer can give.So even though the transformer makes 50 watts available, a single tda2050 would use only about 20 watts. That's great, because you want stereo, so you basically have two identical circuits and in total, the two amplifier chips would use about 40 watts, which is below the 50 watts the transformer is capable of.The gain of the amplifier... normally, you don't mess about with it, you just set it to a reasonable value (the one recommended in the datasheet and mentioned on that website with hi-fi amp based on tda2050) is a good one. You can always adjust the volume from your sound card. Either way, you can adjust that quite easily on a lot of amplifier chips.The LM386 probably needs one because it distorts a lot otherwise... the lm386 is lousy for powering speakers like the ones you say you have.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 10:04:25 pm
content: Quote from: mariush on May 28, 2013, 08:28:27 pmThank you so much for the information you provided me with ... but still the question remains... what chip you work the besti could search for other transformers on ebay to power the amp but i also have a 9 volt transformer (i know nothing great ) but i think it has 1 primary and one secondary winding on it .Anyway ill post 2 pics of it and ill read again your answer in case some info went unseenthank you so muchEdit : i forgot to add the pics the first time

author: mariush
author_rank: Super Contributor
timestamp: May 28, 2013, 10:35:09 pm
content: Wtf ... why quote my whole post for just two-three lines of text?!Oh man.... you're thick.No chip from the ones above would work best, because there are other chips that are more efficient and with less distortions. But considering you're a beginner, because the parts are easy to find, because it's easy to make the circuit even on a prototyping board, that's why I recommended you that TDA2040 or TDA2050. They're very easy for a beginner. So go with those.I explained in that post exactly what transformer you'd need, or what power supply to use.Some chips can work with low voltage, so they'll need current (amps) to output the audio watts they say they can do. ex TDA1519b mentioned only goes up to 18v but does about 12w (2x6w) with that.Other chips are designed to work with higher voltage but can also work at some low voltage with reduced number of audio watts. The TDA2050 works as low as 10v and as much as 50v, but at 10v it only outputs 2-3 audio watts.The transformer you show in pictures is for 9v... isn't it obvious from my previous comments that it won't be good since TDA2050 can only work from 10v ( or +/-5v, as in split power supply -5v, ground, +5v)Next, I explained already that the amplifier needs an amount of watts to go in it, to output a number of audio watts.Look at the damn plastic case the transformer came in, you will see it says something like 9v 300mA ... that's 9v 0.3 A ... the power would then be 9 * 0.3A = 2.7w. Even if the tda2050 could run at 9v, how many audio watts do you think it could output if you only give it 2.7 watts to play with and the chip is about 50% efficient with such low voltage? I went through all those explanations only to go over your head... damn.That transformer in the pictures is very small, it's 300mA maximum. You can't do shit with it when it comes to audio amplifiers.Look for something in the range of 18v (either with center tap or two 9v secondary windings) or a 24v transformer.Popular values are 12v,15v,18v,20v,24v, 2x9 , 2x10, 2x12, 2x15, 2x18v, 2x20v, 2x24 (if they're separate windings you can use the windings in parallel to have 24v ac at twice the current). The tda2050 can work at up to 50v or +/- 25v so in split power supply you could use up to 2x18v and in single power supply you could use up to 24v AC or a transformer with 2x15v in series.Look for a rating of at least 40VA. if it doesn't say an amount in VA, it should say amps ... 40 VA / 24v = 1.6A ... look for anything above 1.5A or 40VA.Such transformer would be heavy, about 1 Kg, here's some examples of transformers that would work for two separate tda2050 (so you have stereo) :http://goo.gl/MxAjMLook at the pictures to get an idea of size, look at details to see the weight, look at datasheet if you want... smallest (in voltage) selected there is with 2 12v secondaries which can be linked together to give you 24v AC rms, which when is converted to DC gets you about 32 V DC which is good enough for a lot of audio watts.The cheapest there is even better with 2x15v dc, you could make even the split power supply version of the amplifier and it would give a lot of power.Alternatively, you can get a 24v power supply, which may be cheaper:http://www.ebay.com/itm/AC-220V-to-DC-24V-3A-72W-Switch-Power-Supply-Transformer-for-LED-Illuminated-/360525805977?pt=AU_B_I_Electrical_Test_Equipment&hash=item53f1033999http://www.ebay.com/itm/AC-220V-to-DC-24V-3A-72W-Switch-Power-Supply-Transformer-for-LED-Illuminated-/380532239639?pt=AU_B_I_Electrical_Test_Equipment&hash=item58997d2d17QuoteOf course it has one primary and one secondary, otherwise it wouldn't be a transformer, it would be a choke, or inductor.Like I said, if it's only one secondary you can do the single power supply design, if you have two windings you have the option to do the split power supply or just connect the two windings in series to get one single big winding and do the single power supply design.

author: IanB
author_rank: Super Contributor
timestamp: May 28, 2013, 10:45:47 pm
content: Chris: a key thing is what do you want to do with this amplifier? What is your input source? What is the listening environment? A tiny speaker with low power can easily be enough to listen to in a quiet room. If you want a lot of sound you will need bigger speakers to go with the bigger amplifier. Tiny speakers will just sound tinny at high volumes.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 28, 2013, 11:18:29 pm
content: Quote from: IanB on May 28, 2013, 10:45:47 pmWell you are right i left this info out of the conversation for good.This amp will be made for medium sized, and not so quiet room.Ill be using it with my bass guitar and i am planning on using small to medium sized speakers with a wooden box so it amplifies the sound.I could also have a 3.5 mm jack (input) so i can plug in my phone to use it as a normal amp.I am not planning on having it working with only the on board speakers.2 more outputs will be also used (one 3.5mm and one 6.4)So to sum it up i want it to have2 inputs 3.5 and 6.4and 3 outputs speakers,3.5 and 6.4 (for use with an actual amplifier)

author: madires
author_rank: Super Contributor
timestamp: May 29, 2013, 01:32:25 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 11:18:29 pmWith 2" speakers you'll get a very lousy bass. If you got a proper datasheet for the speakers we could calculate the wooden cases volume required to improve bass, but I doubt it would help much. Better go for 8" speakers and design the amp for about 25W at least.

author: FJV
author_rank: Regular Contributor
timestamp: May 29, 2013, 07:01:01 pm
content: Quote from: ChrisGreece52 on May 28, 2013, 09:32:44 amUse the speaker as a driver for a horn speaker.source :http://en.wikipedia.org/wiki/Horn_loudspeakerQuote

author: madires
author_rank: Super Contributor
timestamp: May 29, 2013, 09:04:58 pm
content: Quote from: FJV on May 29, 2013, 07:01:01 pmBut not for a bass guitar :-) Horn speakers are used for midrange and high frequencies.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 11:59:37 am
content: Quote from: madires on May 29, 2013, 01:32:25 pmI dont want something loud because i will mostly use my pc speaker system (25watt RMS).

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 12:03:18 pm
content: Quote from: madires on May 29, 2013, 09:04:58 pmSo i wont do it because i will use frequencies as low as 30 HZ.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 12:05:58 pm
content: Quote from: mariush on May 28, 2013, 10:35:09 pmThe transformer in the picture is a 500mah 9 volt one but i will need more info about connecting it in parallel so i can increase the voltageAlso sorry about the huge quote and sorry for my late response i just had time to read and answer.

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 12:48:59 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 11:59:37 amWhich type do you got? Stereo squawk plastic boxes, 2 tiny speakers with a subwoofer cube or something more usable?

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 12:53:18 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 12:03:18 pmThe 2" speakers will fall off around 100Hz very quickly, maybe even at a higher frequency.

author: mariush
author_rank: Super Contributor
timestamp: May 30, 2013, 12:55:45 pm
content: QuoteDude...You have voltage.You have current.Voltage multiplied by current gives you power.That transformer is 9v 0.5 A ... that's 4.5 watts.No matter how many you put in parallel, the voltage remains 9v, just the current doubles, triples etcNo matter how many you put in series, the current remains 0.5A, just the voltage doubles, triples etc9v is too low for a tda2050. No matter how much current you'd have by putting transformers in parallel, you still have just 9v. If it starts at 9v, a tda2050 will only output about 1-2 audio watts, so the chip will only use about 3-5 watts (0.3-0.5 amps) out of how many amps your transformers in parallel would be able to provide.If you put 9v transformers in series, you may have 18v, 27v, 36v ac or dc but your current will still be 0.5aLet's say you put 3 in series to get 27v 0.5a. That's 13.5 watts. I don't know if it's 9v ac rms or 9v DC coming out of that. Let's just say 27v DC.If you go in datasheet at the graph, you look at +/- 13v (because the graph is for split power supply) and you see the amplifier chip has the potential to output up to about 7 watts. At about 60-70% efficiency, that means that to output a single channel (one amplifier), to output about 7 watts of audio, the chip will use about 10 watts.Your 27v 0.5a will be enough, for ONE channel.If you put two amplifiers, one for each channel in stereo, they'll both use about 10 watts, 20 watts in total... but your power supply can only provide 13.5 watts. Your power supply is undersized, even with 3 transformers of that type in series.Do you understand the concept that the amplifier can not output audio watts if there's not enough power at the input? If you give it 10 watts from the mains, how do you expect to get 20 audio watts?Use that 9v transformer for other stuff, it's not suitable for audio amplifiers.Like I said, you need something like 24v AC rms 40-60 VA (about 1.5A) to get about 20-25w of sound.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 02:17:08 pm
content: Quote from: madires on May 30, 2013, 12:48:59 pmSomething more usable its pretty old but still going strongIts a Logitech X-420 2.1 system.2 satelites and one subwooferhttp://www.newegg.com/Product/Product.aspx?Item=N82E16836121010I got it for about 7 years .... ( i did not know that it has been so long ... )good quality wooden woofer and i think it is the best i had (and the first i had)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 02:18:06 pm
content: Quote from: madires on May 30, 2013, 12:53:18 pmwell that sucks.......

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 02:26:49 pm
content: Quote from: mariush on May 30, 2013, 12:55:45 pmWell you will be happy for this !!!! i GOT IT finally i was confused (very confused) but now i got everything but in your reply sou said something that is well suited for me.you said that if i connect 3 windings in series i will get 13.5 watts for power ... thats more than enough for one channel use2 channels is optional as i said.

author: mariush
author_rank: Super Contributor
timestamp: May 30, 2013, 02:40:18 pm
content: nevermind. I read incorrectly and thought you meant parallel.Anyway, it's just stupid to use three transformers, unless you already have them.Just go buy a 24v ac transformer rated for about 20 watts at least, they should be cheap. Or.. I don't know, maybe find two car/motorbike batteries and put them in series to get 24v.

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 03:07:38 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 02:17:08 pmI see. IIRC the satellites got a second passive speaker to boost lower frequencies. Those are ok for FPSs but lack a proper frequency response for higher frequencies. Midrange is "thin" and high frequencies are poor. But some people like that kind of sound. Just don't try to play classic music :-)

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 03:19:26 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 02:18:06 pmThat's why I recommend a 8" speaker. If you add a bass booster to your amp you'll get away with a smaller speaker (6"), but I woudn't go any smaller. Driving such a speaker with 10W should sufficient for a quiet midsized room. With a noisy background (talking people) you have to crank up things considerably.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 04:45:36 pm
content: Quote from: mariush on May 30, 2013, 02:40:18 pmThats okQuoteNo i do not have them but i thougth i could put 3 Windings in series (not transformers)AndQuote24v ACyou mean just a regular 220 Volt 50/60 hz to 24 DC right???Also from another topic a member suggested that i whould look for the power the transformer can deliver so if i want a dual signal amp i am going to need at least 20 wattsRight

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 04:47:51 pm
content: Quote from: madires on May 30, 2013, 03:19:26 pmWhat would you suggest with a medium sized room with medium silence level8" with 15 watts will be good ?

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 05:19:52 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 04:47:51 pmCould work, but it's better to have some reserves, like 30W. The TDA2050 delivers 32W but at high power levels the distortion increases. Give it a try :-) If the TDA2050 doesn't provide enough power you could upgrade later on.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 09:40:21 pm
content: Quote from: madires on May 30, 2013, 05:19:52 pmok but 30 watts??? thats sounds a lot ....if i could find a transformer 12 volt it had to be 2.5 amps ... thats easy to find rightif i buy a 12 volt 3 amp power supply it would be more than enough to power it on !!!

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 09:41:54 pm
content: thats the first thing i came up when i searched 12 volt 3 amphttp://www.ebay.com/itm/36W-12V-AC-DC-Power-Supply-3-Amp-12-Volt-Adapter-LCD-3A-Charger-Laptop-5-5-2-5mm-/270881755391?pt=AU_Laptop_Accessories&hash=item3f11cf90ffdoes it worth it or it will be crappy ?

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 09:52:38 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 09:40:21 pm12v with 2.5A will give you about 25W DC. Now we have to consider the efficiency of the amp (around 2/3) and end up with 16W audio. If you keep things modular, you can start with that transformer and a TDA2050 module. If you need more power later on upgrade to a higher rated transformer. The old one will be useful for another project :-)

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 10:01:49 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 09:41:54 pmBetter stay away from SMPSUs. Mariush suggested a 24V transformer, I second that. 24V 50VA should be a good choice.

author: IanB
author_rank: Super Contributor
timestamp: May 30, 2013, 10:13:49 pm
content: Let's be realistic now. How much sound do you need to practice guitar with? It's all very well talking about 15 W, 25 W, etc, but that's a lot! As I mentioned before, battery powered radios can easily fill a room with sound, and there is no way you can get 15 W out of some little alkaline batteries.Yes, a proper big hi-fi amp might need a big heavy transformer, but a little practice amp as a first electronics project? I think we need to get down to earth here.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 10:23:25 pm
content: Quote from: IanB on May 30, 2013, 10:13:49 pmRight i am sorry but i am figuring this out as i am going through ...... so we have new specsNON portablesinge or dual signalloud but not SO loud (medium sized room medium noise level.Taking into account all the things you suggested above i wont need something more powerfull than 25 watts so we have that limit .With this in mind i am looking for a power supply that it can output up to 30 watts (5 watts will be lost as heat right ? )

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 10:49:42 pm
content: Quote from: IanB on May 30, 2013, 10:13:49 pmA decent guitar amp has got about 15-30W and a quite large case (large speaker). If you want to keep the guitar amp small, i.e. using a smaller speaker, you'll need more power to compensate the size reduction. A big HiFi amp got much more power to be able to deliver a large dynamic range as required for listening to classic music. If you're looking for simplicity for a beginner there's not much difference between 5W or 150W, tons of inexpensive and simple amp ICs and modules are available.

author: madires
author_rank: Super Contributor
timestamp: May 30, 2013, 10:57:00 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 10:23:25 pm30W power in and 20W audio out should be fine.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 30, 2013, 10:59:07 pm
content: Quote from: madires on May 30, 2013, 10:49:42 pmExcactly i am looking for something basic but with ass little distortion as i can get ... :S

author: IanB
author_rank: Super Contributor
timestamp: May 30, 2013, 11:17:20 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 10:59:07 pmYou know guitar amps are commonly designed toadddistortion, right? (Albeit nice distortion, not horrible distortion...)

author: mariush
author_rank: Super Contributor
timestamp: May 30, 2013, 11:43:01 pm
content: Quote from: ChrisGreece52 on May 30, 2013, 09:40:21 pmQuoteMY GOD ..I went through this 3 or 4 times already in this thread12 V DC = +/- 6 V (±Vs) ====> 2-3 audio wattsIt's pointless to get a 12v transformer even if it's rated for 2.5A because the tda2050 WILL NOT USE THE CURRENT it has available. It can only output 2-3 watts at that voltage.You can use an ATX power supply with 40 Amps on 12v and it would still only make only 2-3 watts of audio.YOU NEED LARGE VOLTAGEA 24 V AC transformer will give you when rectifier 24 x 1.414 = 33.9v. With diode drops, you have 32V which is below the maximum of 50V the chip supports.32 V DC = +/- 16vso on the graph that shows you it the amplifier will output about 13-15 audio watts there.13-15 watts of audio is enough for a room and on par with the speakers you have.To get about 13-15 watts of audio, the amplifier will waste about half of that as heat, so it would use about 20 watts.madires told you that you can get up to 32 watts from this TDA2050 chip, but ONLY if it receives about 45-48 volts (close the maximum of 50v it supports). You can see that on the graph above. The output power has a direct relation with the input voltage.A 24v AC 20VA will be enough for ONE CHANNEL (mono), 15 watts of audio max. If you'll want stereo, you make two copies of the amplifier and get a 40VA transformer or better.I only told you about 12v in the first posts because it's a common voltage you have in your computer power supply so when making an amplifier, you could just connect it to the computer power supply and test it. This way you'd only get 2-3 watts of audio. After that, you could just get a big transformer when you have money (or when you find one), and then you have big output.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 31, 2013, 08:21:16 am
content: Quote from: IanB on May 30, 2013, 11:17:20 pmsome nice distortion effect activated by a switch would be fine but its a bass guitar so it would not be vital but pretty fun to have

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 31, 2013, 08:23:48 am
content: Quote from: mariush on May 30, 2013, 11:43:01 pmI forgot about that to be honest sorry

author: madires
author_rank: Super Contributor
timestamp: May 31, 2013, 01:16:28 pm
content: Quote from: IanB on May 30, 2013, 11:17:20 pmEither you go for a tube amp or get a guitar pedal for that :-) There isn't any nice distortion with a modern amp. But you can add a "nice distortion" effect in the preamp-stages of the guitar amp. That's the common way used by most guitar amps.

author: madires
author_rank: Super Contributor
timestamp: May 31, 2013, 02:10:04 pm
content: Quote from: ChrisGreece52 on May 31, 2013, 08:23:48 amIf you have no constraints for the PSU use higher voltages and split voltages (+/-), based on the amp IC or module you're using. If you have to use 12V go for a car audio amp IC, which is optimized to deliver more power at that low voltage. But use linear PSUs, no SMPSUs, because those give you a headache. They're much cheaper, but you have to add a lot of filtering (large and expensive parts) to make them usable for audio amps.Back to Watts. For a bass guitar you obviously want to have a guitar amp with good bass. The first thing to consider is the human ear (see dBAhttp://en.wikipedia.org/wiki/A-weighting). There's a huge difference in loudness if listening to 1W audio with 1kHz or 100Hz. IanBs transistor radio with a decent speaker works fine for a midsized room as long as the audio is in the kHz range. But if you go down with the frequency you have to provide much more power to achieve the same loudness as the 1kHz signal got. Therefore you need a large speaker capable of providing a good frequency response down to the 30Hz you like to have. And you need some Watts to drive that speaker and to compensate for the dBs the speaker can't deliver and the dBA concept. If you use a more small-ish speaker you'll need more Watts and an adjustable bass booster. The latter would be a good idea anyway, also for a large speaker. And for audio mostly in the bass range a slighty oversized PSU is desirable, because a overdriven PSU doesn't let the amp give you nice bass. If you want 30W audio use an amp with >=50W. It's a bad idea to max out the power specs of the amp (increased distortion, bad sound and so on). That's all basic audio 101.

author: SeanB
author_rank: Super Contributor
timestamp: May 31, 2013, 03:16:46 pm
content: Distortion is easy, LM386 run till it clips.............Or 2 back to back diodes and a low value series resistor with about 2Vpp of signal works as well.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 01, 2013, 10:30:56 am
content: Quote from: SeanB on May 31, 2013, 03:16:46 pmyeah but lm386 is a crappy amp so i need something with more power.

author: madires
author_rank: Super Contributor
timestamp: June 01, 2013, 02:51:31 pm
content: Quote from: ChrisGreece52 on June 01, 2013, 10:30:56 amI think he meant that you could use the LM386 as a preamp stage just to generate the distortion.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 01, 2013, 11:32:02 pm
content: Quote from: madires on June 01, 2013, 02:51:31 pmoohhh ok ... but why should i use lm386 as a preamp for distortion while i can just change the value resistors i can use to change the gain (that is what i mean by distortion it may be wrong.)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 01, 2013, 11:46:49 pm
content: So finally after all i learned i want to go with something outputs 30 volts (15 +/- )watts thats the best state ( distortion wise) but i can not find a transformer suitable for the application)At 24 watts my goal (output power )the chip will dissipate 14 watts of heatso i need something that outputs (24+14 =38) 38 wattsfrom the formula that i saw in an answer we have P = V I so I = P/V => I = 38/30 = 1.266 Amps (pretty good and achievable)I posted this so i make sure that i wont screw the calculations upThank youDatasheet :http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXyuqt.pdf

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 01:15:31 am
content: Yes, sounds about right.A 24v transformer will have a peak DC voltage of 1.414 x 24v = 34v. With the drop in rectifiers, that's about 31v.So +/- 15v is doable with a 24v center tap transformer and big capacitors on the output (let's say 2x3300-4700uF 25v on each side, negative and positive, so 4 capacitors in total ), or if you make the design in the datasheet that's with single power supply, about 8200-10000 uF 50v (in whatever capacitor combination you want, you can put capacitors in parallel to increase size)A transformer rated for 24v AC rms 40-50VA would do.See below for some examples

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 01:47:12 am
content: And don't forget about the heatsink.At low volumes, it won't waste that much power, but if you get it going at high output, it will waste 10-15w of power.Tiny heatsinks don't work, like the datasheet says you need a relatively big heatsink (compared to what you may be used to) with low thermal resistance.Either screw it on a CPU heatsink with the cpu fan running at low speed, or get a large heatsink like the one in this picture:http://www.ebay.com/itm/100x55x10mm-Aluminum-Heatsink-for-Electronics-Computer-Electric-equipment-H104-/171015086436?pt=LH_DefaultDomain_0&hash=item27d14b2164http://www.ebay.com/itm/100x55x10mm-Aluminum-Heatsink-for-Electronics-Computer-Electric-equipment-H104-/200801981466?pt=LH_DefaultDomain_0&hash=item2ec0bb141ahttp://www.ebay.com/itm/100-45-10mm-Aluminum-Heat-Sink-TO-220-w-o-stand-for-LED-Power-IC-Transistor-/260865037352?pt=LH_DefaultDomain_0&hash=item3cbcc49428http://www.ebay.com/itm/100x35x10mm-High-Quality-Aluminum-Heat-Sink-For-Computer-Electronic-H62-/181110957180?pt=LH_DefaultDomain_0&hash=item2a2b0de47chttp://www.ebay.com/itm/100x35x10mm-High-Quality-Aluminum-Heat-Sink-For-Computer-Electronic-H62-/190808608538?pt=LH_DefaultDomain_0&hash=item2c6d144f1aIf you get something like the above, you must screw the chip somewhere close to the middle of the heatsink, not on the side. Don't forget to use some cpu thermal paste between heatsink and the chip.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 07:26:07 am
content: Quote from: mariush on June 02, 2013, 01:47:12 amI will get something from the above ones i was thinking about the first one.And of course middle.But shall i use thermal paste?? (like in a CPU for better heat transmision)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 07:27:55 am
content: Quote from: mariush on June 02, 2013, 01:15:31 amGot itbut i could not find a proper power supply at ebay ....

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 02:20:53 pm
content: Quote from: ChrisGreece52 on June 02, 2013, 07:27:55 amYou must really suck at searching then. from cheaper to more expensive20VA : 2x24v or 1x48v with center tap (just connect the middle terminals) - good for the third design in the picture a few posts above.20VA is a bit low but this is a cheap transformer.http://www.ebay.com/itm/CTFC20-24-Camdenboss-Transformer-20Va-2-X-24V-/360622938744?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53f6cd5a7850VA : 2x9v or 1x18v with center tap. Good for about +/- 11v so obviously less output powerhttp://www.ebay.com/itm/CTFC50-9-Camdenboss-Transformer-50Va-2X-9V-/130877005329?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e09e1150VA : 2x18v or 1x36v with center tap. Good for the third design, just connect the middle terminals together.Youmightbe able to use it for first design (split supply) or second design, but you'd have to be really careful. 18v will give you a peak of about 26v, the bridge rectifier will drop about 1.5-2v so you're very close to the +/-25v absolute limit of the tda2050, if you ignore that the transformer may output 5-10-15% more at low loads. You could put 2-3 big diodes on each output after the bridge rectifier, to drop the voltage about 2v more, so you'd have +/- 22-23vhttp://www.ebay.com/itm/CTFC50-18-Camdenboss-Transformer-50Va-2X-18V-/130891176802?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e79b8db6250VA : 2x12v or 1x24 with center tap. Exactly what you were searching for, this would give you +/-15vhttp://www.ebay.com/itm/CTFC50-12-Camdenboss-Transformer-50Va-2X-12V-/130877006916?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e0a444100VA 2x24v or 1x48v only for second or third design of power supply. Added because it's cheap for the VA rating and it's good enough to power 2-3 channels in case you want to make stereo or 2.1for second design , connect the windings in parallel, 1 to 3 , 2 to 4, and you have a single 24v transformer with twice the current capability. use bridge rectifier and capacitors to get about +32vfor third design, connect 2 and 3 and you have a 48v with center tap, so third design will get you about the same +32-34vhttp://www.ebay.com/itm/MCF-B19624F-Transformer-100Va-2-X-24V-/130877003135?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e78e0957f100VA 2x12v or 1x24 with center tap. Exactly what you need, but enough VA for 2-3 identical ampshttp://www.ebay.com/itm/CTFC100-12-Camdenboss-Transformer-100Va-2-X-12V-/360622945129?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53f6cd7369As a sidenote, this guy simply buys these transformers from Farnell and adds his fees then sells on eBay.Farnell doesn't ship directly to Greece, but they have a distributor in your country:Darlas Electronic Applications SA5, Kimonos Str122 44, EgaleoAthensGreeceTel: +30-210-59.86.179Fax: +30-210-59.11.161Email: darlas@darlas.grWeb:http://www.darlas.grThey have an online store in which you can see the prices, for example here's the link to 86 pages of transformers to choose from :http://www.darlas.gr/comersus/store/comersus_listCategoriesAndProducts.asp?idCategory=17521983And if you search by product name, for example CTFC50-12 for the 2x12v 50VA transformer that matches your needs, you can find it at 20 euro on their site:http://www.darlas.gr/comersus/store/comersus_viewItem.asp?idProduct=1890021You can go on farnell.com to the transformers category :http://uk.farnell.com/isolationUse the filters there to select 2x12v, 2x15v, maybe even 2x10v (this should give you about +/-13v) , maybe also check 24v,30v,32v (they may have center tap but you only see if you check datasheet), maybe also check 2x18v if you may change your mind and do single power supply (third design)select minimum VA rating 20va, maximum 100-150va, then look in the results and find something you like. Get the product code and enter it on darlas.gr site in the search box to see how much it costs for that store to get it for you.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 02:46:19 pm
content: Quote from: mariush on June 02, 2013, 02:20:53 pmThanks for your suggestions.First i do not suck i was just searching for the wrong thingi searched for 30 volt 1.5 amp power supply ( and to be sure i did this because 30 1.5 = 45 watts 24 for the amp and the rest will be dissipated as heat)Also thanks for your suggestions they are pretty goodbut i an not familiar with tranformers (at a wide range).But i could make this workSecond thing : the prices a re excellent and thanks for your considerationand finally third i have checked out the darlas store and i have 2 comments1 : most of the things that it sells are overpriced2:shipping from Athens to Kavala is more expensive than some buyers UK products.

author: madires
author_rank: Super Contributor
timestamp: June 02, 2013, 02:59:56 pm
content: Quote from: ChrisGreece52 on June 02, 2013, 07:26:07 amYep! If you need isolation add a mica plate or use a sil-pad without the thermal paste. Also use an isolation thingie for the screw. You could mount a large flat heatsink at the backside of your speakers box. Make a matching cutout in the backside, of course a little bit smaller than the heatsink to get an overlapping area for adding a sealing tape and bolting down the heatsink. That's the standard way for active speakers.

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 03:31:53 pm
content: Yes, you need to have good contact between the tda2050 and the heatsink. cpu paste would probably be easiest for you to get access to and works great.The tab on tda2050 (the large metal backside) is connected to pin 3, which is -Vs (negative voltage) when you use split power supply. If you use single power supply version, -Vs is basically ground.Since you use transformer, the outputs -Vs and Vs are floating, so it's not a problem that the whole heatsink will stay at -Vs, you won't get electrocuted.You just have to make sure the heatsink doesn't connect to ground somehow. For example, if you plan to put this in a metal box, make sure the heatsink doesn't touch the metal case.If you don't want to worry about it and have the heatsink isolated from the tda2050 (to screw it on a metal case for example to enlarge its size using the metal of the case), then you must insulate the back of the chip from the heatsink.There are ready made pads (rectangles of a certain material) which are good for thermal transfer, and you don't need cpu paste with those.Depending on the material they insulate the metal of the chip from the heatsink, or they don't. One pad called sil-pad does insulate:ex :http://uk.farnell.com/bergquist/2015-54/sil-pad-2000-015-to-220/dp/681118Same with mica based pads:http://uk.farnell.com/multicomp/mk3306/insulating-kit-mica-to-220/dp/520214But just using a pad is not enough, you also have to insulate the screw going through the heatsink... there is a type of plastic ring that goes into the hole on the tda2050 that guides the screw so it never touches the metal. You can see one of those plastic thingies in the link above.You can find all of the above on ebay but be careful because these are generally in a standard shape, either for to-3, to220, to247 and your tda2050 is in pentawatt size, which is a bit larger so you probably won't find these cheap insulators but rather only larger pads from which you can cut exactly the size you want.Overall I'd say it's not worth it, should be easy to just make the heatsink not touch anything, in the worst case scenario just put it on some nylon spacers like these, which you could also find on ebay or in old computer cases ...http://uk.farnell.com/duratool/d01455/pcb-spacer-support-nylon66-natural/dp/1733383http://uk.farnell.com/duratool/d01472/pcb-spacer-support-nylon66-natural/dp/1733402http://uk.farnell.com/duratool/d01470/pcb-spacer-support-nylon66-natural/dp/1733399or you could also just get some electricians tape and put several layers of tape where the heatsink might touch if it flexes, bends etc

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 06:32:49 pm
content: Thanks for the answer.So bottom line i must pay great attention to the heatshink .I need the simplest way of all suggested aboveAlso i had not the fear of electrecution until now thanks for that

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 06:57:09 pm
content: You'll have mains electricity only up to the terminals of the transformer. You isolate those with electricians tape, heatshrink, whatever.The outputs of the transformer 24v ac, or +15v , -15v etc are all floating. It's also low voltage so it's not really a safety risk unless you put your tongue on it or something like that.You just have to know that the metal back of the chip is connected to what would be -15v on your power supply. Traditionally, circuit boards are grounded to what they're screwed on (ex on motherboards ground in the connector coming from the psu is connected to the metal case through the screws sometimes) so if you do that and the metal heatsink touches the metal case you have a short circuit.If you put the prototyping board and the heatsink in a plastic box (abs) the heatsink is basically not touching or shorting anything, so you don't need insulation. And if you touch it with your hand, at best you're going to feel some tingling in your fingers and the chip may reset or make awful noise (you're may short the -vs to ground through the big resistor your body forms)

author: madires
author_rank: Super Contributor
timestamp: June 02, 2013, 07:00:15 pm
content: Quote from: ChrisGreece52 on June 02, 2013, 06:32:49 pmYou're welcome!

author: madires
author_rank: Super Contributor
timestamp: June 02, 2013, 07:14:21 pm
content: Quote from: mariush on June 02, 2013, 06:57:09 pmI'd suggest to mount the TDA isolated if the heatsink isn't inside any non-conducting box to prevent trouble with the input signals. Putting a 15W heater inside a closed plastic box isn't a good idea IMHO. The best way is to place the heatsink at the backside of the speaker box for proper air convection.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 08:57:11 pm
content: Quote from: mariush on June 02, 2013, 06:57:09 pmDamn i was looking forward to licking a transformerAnyway ill be carefull and i will insulate the terminals (after soldering them) with tape and then heatshrink tube (just to be extra sure) as for the case i will go with a wooden box so no insulation needed .

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 02, 2013, 09:20:59 pm
content: Quote from: madires on June 02, 2013, 07:14:21 pmIll think of installing 2 small 40mm fans so they keep the box cold

author: mariush
author_rank: Super Contributor
timestamp: June 02, 2013, 09:55:49 pm
content: No need for that man.Just drill some holes in the case where the bottom of the heatsink should be, and some holes towards the top, somewhere above the heatsink.Hot air tends to rise up, so colder air will be sucked in through the holes at the bottom and the warm air will get out through the holes at the top ... it's called natural convection :https://en.wikipedia.org/wiki/ConvectionIf it will get really hot, get a regular 80mm - 120mm that you can find basically anywhere and put it to blow the warm air OUT of the wood box .. you can power it directly from 15v through a dropper resistor to get the fan running at 6-8 volts so that it won't be noisy.

author: madires
author_rank: Super Contributor
timestamp: June 02, 2013, 10:02:19 pm
content: Quote from: ChrisGreece52 on June 02, 2013, 09:20:59 pmPassive cooling rulez! :-)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 03, 2013, 12:37:49 pm
content: Quote from: mariush on June 02, 2013, 09:55:49 pmThat would save me time thank you

author: smashedProton
author_rank: Frequent Contributor
timestamp: June 04, 2013, 07:17:05 am
content: Yes, if your speakers are well made you can venture past their rated values. But I would not do that. Also, be sure not to clip your amplifier. That is very bad stuff that will burn up the coil. Remember that speakers are not ac driven heating elements. Also, the best way to get more output is RESONANCE. Make a ported box. T-lines are also good because they can cause the backpressure to constructively interfere with the foreward.

author: jmacqueen
author_rank: Contributor
timestamp: June 04, 2013, 08:27:48 am
content: Wow what a thread, why not something like the old pignose amp circuit ala 1970's. great for guitar practice, easy to build, should be able to get transformers and even the other components from scrap electronics like old car stereos or old busted radios. Been used for years and years now.. by all the greats. not hard to make, playing with different transformers to get the drive and tone you like..schematic...http://music-electronics-forum.com/attachments/2913d1218923726-pignose-model-7-100.gif

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: June 05, 2013, 07:20:00 am
content: Quote from: jmacqueen on June 04, 2013, 08:27:48 amcool but i dont think it will work with bass guitar.... i am a bit comfused thought ... i really want to make the amp myself and dont buy one already made ....

author: cais
author_rank: Newbie
timestamp: November 23, 2018, 09:15:41 pm
content: Hola buenas tardes, tengo una placa igual y quisiera usarla, pero no dispongo del esquema de conexiones en las borneras, sería tan amable de facilitarmela. Muchas gracias

author: cais
author_rank: Newbie
timestamp: November 23, 2018, 09:17:06 pm
content: Hello good afternoon, I have an equal plate and I would like to use it, but I do not have the connection scheme in the terminals, it would be so kind to facilitate it. Thank youHola buenas tardes, tengo una placa igual y quisiera usarla, pero no dispongo del esquema de conexiones en las borneras, sería tan amable de facilitarmela. Muchas gracias

author: Zero999
author_rank: Super Contributor
timestamp: November 24, 2018, 09:10:55 pm
content: Quote from: cais on November 23, 2018, 09:17:06 pmPlease create your own thread, rather than bumping a really old one.