Texas Instruments 3116D (ClassD) amp chip - Page 1
Forum section: electronics / projects

author: DW1961
author_rank: Frequent Contributor
timestamp: August 09, 2020, 09:21:51 pm
content: The amp I have uses the TA 3116D chip, and they manufacturer actually makes one with 2 of those chips, and states twice the power.Amp:https://www.amazon.com/gp/product/B07NY19148/ref=ask_ql_qh_dp_hza"If you use a full power supply, it is 200W @ 4 ohm, 150W @ 6 ohm, 100W @ 8 ohm."TA 3116D spec sheet:https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2"The TPA31xxD2deviceis a highly efficient Class D audio amplifier with integrated 120m Ohms MOSFET that allows output currents up to 7.5 A. . . Wide Voltage Range:4.5 V to 26 VSo how are they getting 200 watts out of two of these at 4 Ohms with a 24-26V driver? (Max is 26V)

author: magic
author_rank: Super Contributor
timestamp: August 10, 2020, 06:37:37 am
content: There aren't too many ways to combine two power amps. Either in parallel or in series (bridged), depending on whether current or voltage is the limiting factor.

author: mikerj
author_rank: Super Contributor
timestamp: August 10, 2020, 08:44:09 am
content: Quote from: DW1961 on August 09, 2020, 09:21:51 pmA combination of paralleling the outputs of two amplifiers to increase drive capability, and by making very optimistic claims (aka lying)You can't can't bridge the output of these amps as they already a bridged architecture internally.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 10, 2020, 05:58:10 pm
content: Quote from: mikerj on August 10, 2020, 08:44:09 amI guess you could use a higher voltage driver and split the voltage across both chips? However, that's not what they are doing. They are using a19V power supply, and they do admit that the 19V power supply will not put out max power specified by the chips. I'm just wondering that using a 19V power supply, even one chip will be lower than the specs state, so how can they power two of them with the same power supply and get more power out of the chips?

author: lutkeveld
author_rank: Regular Contributor
timestamp: August 10, 2020, 07:53:54 pm
content: You can get 100W out these chips if you parallel the outputs (PBTL) but then you need a 2 ohm load.So probably the spec is not completely false, but its: 2x100W at 2 ohm each.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 11, 2020, 04:54:48 am
content: Quote from: lutkeveld on August 10, 2020, 07:53:54 pmYeah that's it.But what I don't get is why do you need two of these chips?If you use a 24V driver into 8 Ohms, you get 72 watts at 3 A.What is the benefit of running two of these when the power stays the same, and one amp chip is capable of putting out the same wattage using the same driver for both chips?

author: lutkeveld
author_rank: Regular Contributor
timestamp: August 11, 2020, 05:43:53 am
content: Because now you have 2x100W at 2 ohm instead of 2x50W at 4 ohmYou are right that with the same drivers, nothing changes. But you can use different drivers, or put extra drivers in parallel.And of course it sounds better for marketing

author: DW1961
author_rank: Frequent Contributor
timestamp: August 11, 2020, 06:45:39 am
content: Quote from: lutkeveld on August 11, 2020, 05:43:53 amSo they put two chips in that amp, and use the same power supply, and get nothing from it except marketing hype?

author: mikerj
author_rank: Super Contributor
timestamp: August 11, 2020, 09:02:58 am
content: Quote from: lutkeveld on August 10, 2020, 07:53:54 pmBut not using the 25v/3Amp (i.e. 75Watt) power supply that they specify.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 12, 2020, 01:34:56 am
content: Quote from: mikerj on August 11, 2020, 09:02:58 amHere is another one stating the 200 watts, but they do specify 2 ohms. They are using a 24v 4.5 amp driver.https://www.amazon.com/gp/product/B0887VX6H1Here are the 3116D specs "100 watts at 2 ohms mono (page 1).https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2That one is coning to my house free of charge. The last one I got from a different seller on Amazon had some nasty hiss when turned up all the way with no music playing, so I sent it back. I have the single 3116D version now and it's all I need. I remember testing the dual 3116D amp, and I don't know how they are doing it, but it is putting out some serious power. I could really tell because the speakers had a LOT more punch to them.The max power they are going to get with the 24V driver at 8ohms is 72 watts.So again, regardless of how many chips they use, they still have a specific amount of power to use. My argument is that if a single 3116D chip will put out the same watts as two of them, given the same power supply, what is the benefit of using two of them?And, here is it at 8 ohms @ 24V, about 72 watts total. So how dos two of them make more power @ 8 Ohms?

author: tooki
author_rank: Super Contributor
timestamp: August 12, 2020, 08:36:10 pm
content: How is it not clear to you?!?That chip can do 100Wmonointo a 2 ohm load. So they’re using two of them to get stereo.As for total power, remember that you need the voltage to reach the peaks, but that most of the signal is below the peaks. So the power supply doesn’t need to have quite as much power as you think, since capacitors are used to feed current spikes.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 15, 2020, 05:22:19 am
content: Quote from: tooki on August 12, 2020, 08:36:10 pmHey, sorry about the delay. I'm still interested in this topic. I just had some real life things to deal with.I had no idea you could run a chip in mono and get stereo out of them by running two of them in mono. Pretty basic stuff, so I apologize for that.As far as power goes, I'm always talking about continuous power. So if you're running a 24V driver, your max output is going to be 72 watts, right?I just got this amplifier. It looks like the Chinese are upping their game. It's case isverywell made with recessed, high friction knobs and the volume knob clicks as you turn it. It does have some cheesy screen printing on it--lol.https://www.amazon.com/gp/product/B0887VX6H1It uses two Texas Instruments 3116D2 chips (link above) and the TI NE5532 operational amplifier (link below).https://www.ti.com/lit/ds/symlink/ne5532.pdfI'm assuming that's an LFE sub output? It says it is an active sub output.<-------Sorry for end of post attachments. I can;t get the inline function to work.<-----------Not working either.Regardless of power output, I'll bet this thing has some serious punch to it. Makes me want to get a R series Klipsch sub woofer to go with my R-51M Klipsch speakers.

author: tooki
author_rank: Super Contributor
timestamp: August 15, 2020, 12:54:26 pm
content: Quote from: DW1961 on August 15, 2020, 05:22:19 amNo worries, it happens to all of us!Quote from: DW1961 on August 15, 2020, 05:22:19 amThe channels of an audio chain are fundamentally separate. We just control them in (usually) pairs for convenience.Class D amplifiers are a bit of an exception, in that many of them take advantage of the fact that they actually have way more power available than they need, letting them actually alternate powering the two channels, reducing the instantaneous current draw. (This is why you must only bridge class D outputs in the ways listed in the datasheet.)Quote from: DW1961 on August 15, 2020, 05:22:19 amNope. You’re going by the math for DC, but it’s not DC, it’s AC.Some things to understand:1. The supply voltage is what limits the maximum power of the amp, as it is the highest voltage that be present on the output. For any given speaker impedance, it is the maximum voltage alone that limits the power. But it’s a sine wave, so the vast majority of the signal is below the peak voltage.2. Many (most?) class D amps, including the one here, use creative switching to produce both the positive and negative sides of the output waveform from a single-polarity power supply (let’s call this VCC). This means that the output voltage can swing from +VCC to -VCC, meaning a peak-to-peak voltage of VCCx2. So if your VCC is 24V, then your output can swing from +24 to -24 volts, a total peak-to-peak voltage of 48V!3. In a sine wave, the peak voltage is only reached for a tiny amount of time. Most of the time is less. So we measure using RMS, the value of the AC signal given as the DC voltage with the equivalent heating power. For a pure sine wave, the RMS value is the square root of 2 (about 0.707) times the peak voltage (which in an amp is at most the VCC). So for your 24V VCC, the RMS becomes 24x0.707, or about 17V. And that gives you a maximum average power of 36W into 8 ohms (a current draw of 2.125A). (You can also calculate it as VCC2/2x(impedance).)4. Music isn’t a singular, always-full-amplitude sine wave. That’d just be a single loud tone. Nor is music multiple sine waves of different frequencies, but always full amplitude. No, it’s nearly infinitely many simultaneous sine waves of different frequenciesat highly varying amplitudes. Indeed, most of them will befarbelow the peak amplitude (since the peak is necessarily the peaksumof all the frequencies at any instant). The consequence of this is that the average power is far lower than the peak power, easily a factor of halfat full volume.5. As such, while you will need capacitors to ensure the peak current can be supplied, the power supply only needs to be beefy enough to supply the average current. That’s why you can get away with the small power supplies commonly used in audio gear now.And that’s all assuming you’re running it at full blast. At typical home, indoor listening levels, you don’t need but a tiny fraction the power. One of the 3116’s at just 7 volts into 8 ohm speakers is enough to be much too loud to have a conversation, and that’s just 3 watts per channel max. Nighttime watching a TV show, for instance, will have the 3116 drawing maybe 30mA at 5 volts, so 150mW total (and at 5V, the 3116’s quiescent current with no signal is about 15mA, so at most 75mW actually going to the speakers!).A lot of info, but I hope it helps. Of course there are lots of other things that come into play and slightly increase the power needed, but this should help understand why you can’t just apply ohms law to the supply voltage to calculate an amp’s power.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 15, 2020, 05:12:44 pm
content: Quote from: tooki on August 15, 2020, 12:54:26 pmYes, understood. I read a lot about how RMS is calculated and it's the avg of the sine wave and so on.In another thread on the same subject I posted that using the volume knob with my Klipsch R-51M speakers (93dB sensitivity), I can not get it over about half way, which if it is at all accurate is giving the speakers about 11 watts each. It's just glaringly loud at that point. (That's with a 19V power supply.)I went to the Amazon page and asked the seller what the continuous output was at 8 ohms using their 24V power supply:Q: The 3116D chip is only rated 100w @ 2ohms mono. Using the included power supply, what is total power output @ 8 Ohms?A: when you use 8ohm speaker, the total power is 35-50W.I should have asked what the continuous power is, but what he said was accurate given the oms to watts calculations, which would be 35-36 watts continuous. I think he means 35 watts continuous and 50 peak.Back to my question, though:So, my question, again, what is the benefit of using two 3116D chips when you get the same power output as one chip at 8 ohms?

author: DW1961
author_rank: Frequent Contributor
timestamp: August 15, 2020, 05:25:58 pm
content: Just wanted to say that the amp I posted here is not a powered sub out. It requires an active subwoofer--which is good. That leaves all power for the mids and tweets. Damn, I'll bet this thing with a 10" Klipsch active sub and the R-51M speakers as mids and highs would be incredible.

author: TimFox
author_rank: Super Contributor
timestamp: August 15, 2020, 09:18:44 pm
content: Turning the volume control to 12 o’clock doesnotmean you are putting out half power.Look at my earlier response to one of your many posts about estimating your power output and requirements using a CD player.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 15, 2020, 11:04:39 pm
content: Quote from: TimFox on August 15, 2020, 09:18:44 pmI understand that for sure. The point I was making is that the knob is never past a 25-35% when I first hear music. And, that is nowhere near full power because it will continue to get louder all the way to the right stop, when the dial no longer turns. I don't know how many watts it is, but it is nowhere near 50%.As far as testing how many watts are being used at a specific dial indication, wouldn't it be easier to use a MM connected to the amps outputs for volts and a clamp meter to get amps?

author: TimFox
author_rank: Super Contributor
timestamp: August 15, 2020, 11:37:07 pm
content: Again, I refer you to my other post. To determine the output power under continuous conditions, you measure the voltage into a known resistanceRand calculateP=V2/R.The volume control is a log-tapergaincontrol. The output power also depends on the input level.A typical gain control might have a useful range of 40 dB, so half way would be 20 dB below the maximum gain. However, with a “normal” source signal level, the maximum gain may be way too much for the output capability of the amplifier. My good preamp uses a precision stepped-switch attenuator, where the output is shorted at full CCW, with 48 steps. At top center, the attenuation is 24 dB.

author: tooki
author_rank: Super Contributor
timestamp: August 16, 2020, 02:37:12 pm
content: Quote from: DW1961 on August 15, 2020, 05:12:44 pmI don’t think there is one, since with the 8 ohm speakers, you’re hitting the voltage limits before you hit current limits.

author: TimFox
author_rank: Super Contributor
timestamp: August 16, 2020, 05:13:25 pm
content: The conflict between voltage and current limits is why vacuum tube amps use transformers with secondary taps for different load impedance, to get the same power output at different loads. From the tube’s “characteristic curves” one can determine the higher impedance load line (at the plates) that satisfies the voltage and current limits without exceeding the plate dissipation power.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 16, 2020, 06:08:08 pm
content: [ Specified attachment is not available ]Quote from: TimFox on August 16, 2020, 05:13:25 pmHere is something. According to this calculator, you're never ging to get 200 watts out of that amp, not continuous. As Tim has said, sure, with caps and for brief burst, but nowhere near 200 watts continuous. That is, unless the calculator is not taking into consideration other amp related/audio related parameters:Most importantly, the power supply is 24V and 5 Amps. Anyway, I have no idea, again, why they would use two chips with a 24v/5A driver. There must be some reason, at least that's what my head is telling me. In fact, at 2 Ohms, in order to not exceed the driver's 5 Amp max, you get 50 watts total because the voltage drops to 10V. In order to get 200 watts total, you would have to go to 10 Amps/ 20V. (All according to the calculator).The images are suppose to display inline full size, so if they are not, no idea. All options default to end of post thumbnails.

author: tooki
author_rank: Super Contributor
timestamp: August 16, 2020, 07:41:17 pm
content: Youstilldon’t understand the practical significance of the whole RMS vs peak voltage thing I laid out for you in detail.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 16, 2020, 08:23:37 pm
content: Quote from: tooki on August 16, 2020, 07:41:17 pmGonna go back and read that again.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 17, 2020, 12:02:20 am
content: Quote from: tooki on August 15, 2020, 12:54:26 pmOk, so I see how you get peak power from a 24V power supply. I did it like this, becasue the rated power on the supply is 24V RMS:So:24/.707 = 34Vand34*.707=24.7VYes, they are talking about "max" power output, so sure, you can get 200 watts out of a 24V RMS power supply rated at 5A.Back to my original problem, I'm not seeing how you get anymore than 100 watts continuous power at 4 Ohms using that 24V/5A power supply.I think some of my problem is that I don't see where contious power or peak power is stated int eh Texeas Instruments spec file:The chips are rated at peak power of x2 50 watts at 4 Ohms. (Peak, Continuous?)Top of document:https://www.ti.com/lit/ds/symlink/tpa3116d2.pdf?ts=1596921462063&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3116D2Each 3116D chip is rated for a continuous power of 50 watts @ 21V and 4 Ohms. (Total or x2?)Section 6.6AC Electrical Characteristics (Same document)If the continuous power spec means 50 watts total at 4 Ohms @ 21V, then ok:So you can get 100 watts @ 20V and 5A and 4 Ohms from a 24V/5A continuous power supply.So using two 3116D chips, you can get double the power, then, at 4 Ohms. (two chips at 2 Ohms bridged = 4 Ohms.)How am I doing?

author: rsjsouza
author_rank: Super Contributor
timestamp: August 17, 2020, 01:06:31 am
content: Quote from: DW1961 on August 17, 2020, 12:02:20 amTable at section 6.6 of the datasheet indicates 50W continuous at 4 ohms with 21Vcc. According to the description, this is per channel - in BTL it will do 100W under the same conditions. A side note: keep in mind this is under 10% of signal distortion - far from a hi-fi under these conditions (it will have less distortion if driven at lower power).Quote from: DW1961 on August 17, 2020, 12:02:20 amThe output power equals the supply power minus losses - in other words, the efficiency of the circuit. 24V/5A will give you 120W of supply, which may be just enough for continuous operation of 100W total or 50W per channel - the efficiency is shown at figure 23 of the datasheet.Higher peak power may or may not be attained. Section 7 describes the drivers will pull up to 7.5A at peak conditions (which gives a 200W peak under 4 ohms).

author: DW1961
author_rank: Frequent Contributor
timestamp: August 17, 2020, 02:16:27 am
content: Quote from: rsjsouza on August 17, 2020, 01:06:31 amHey, thanks for chiming in.Just so I can understand the technical language, where in that table at 6.6 does it say "per channel" at the 10%THD row?Power to efficiency are understood. It's a good point, but for now I'm just keeping it at theoretical output for simplicity.I just want t get the continuous power aspect down given the power supply of 24V at 5A @ 4 Ohms.If I understand you correctly, this all mean that with two 3316D chips using a 24V / 5A power supply, bridged at 2 Ohms each, for a total, again, of 4 Ohms, they can get theoretical power of 100 watts continuous at 10% THD?If so, we can move on to the problem I have about 8 Ohms loads and using two of these chips. That would be about 72 watts continuous from the power supply. Well, I'll jsut sate it again:At 8 Ohms and 24V / 5A = 72 watts.That's as much power as it can make.This graph shows a single 3116D chip can do 80 watts continuous. However, the PSU is only going to give it 72 watts.At .1% THD it will do 66 watts total.Again, the graph says "maximum power" and says nothing about peak or continuous. I don't know what "Maximum Output Power" means: Peak/Continuous? In any event, if you are running ONE 3116D with a 24v/5A PSU, you get 72 watts total. If you use 2 3116D amps, your continuous output is still going to be no more than 72 watts @ 8 Ohms. I'm only talking about continuous power from the dual 3116D amp chips at 8 Ohms. So what is the benefit of having two chips if you power does not increase over 72 watts, and one chip can use all of it,a nd what's more, at less than .1% THD? I assume you could have even lower THD if both amp chips were putting out a total of 72 watts, but each one was only being driven at 50% power?

author: rsjsouza
author_rank: Super Contributor
timestamp: August 17, 2020, 03:15:30 am
content: Quote from: DW1961 on August 17, 2020, 02:16:27 amThe table itself does not say it. The description at sections 1 and 3 says the device puts out 2 x 50W continuous and section 7.4.1 says in PBTL mode (mono) it puts out 100W. With all that, I infer the information there is related to a single channel.Quote from: DW1961 on August 17, 2020, 02:16:27 amIf I understood correctly your amplifier has two devices in PBTL (mono) mode and each is driving its own 2\$\Omega\$ loudspeaker. If so, figure 22 tells me that, at 24V, it can go as high as 150W each device, rendering your 24V/5A rather inadequate to supply this "beast". To get absolute maximum continuous power, you would need to have a minimum of 300W + efficiency losses.Quote from: DW1961 on August 17, 2020, 02:16:27 amSo, why are you talking about 2\$\Omega\$? Sorry, I really don't get exactly the circling around.Quote from: DW1961 on August 17, 2020, 02:16:27 am24V * 5A = 120W. Where did the 72W come from?With all that, two devices in PBTL mode driving 8\$\Omega\$ should be properly driven by your 24V/5A power supply, given the efficiency would still be well within the tolerance of your power supply.Quote from: DW1961 on August 17, 2020, 02:16:27 amThe characterization having THD+N measurements suggest to me this is continuous - distortion measurements in peak signals is quite difficult to obtain and not very practical.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 17, 2020, 06:17:46 am
content: Quote from: rsjsouza on August 17, 2020, 03:15:30 am

author: TimFox
author_rank: Super Contributor
timestamp: August 17, 2020, 01:25:38 pm
content: So far, the discussion has related to definitions, arithmetic, and careful reading of the data sheets.Do you have thebasicequipment (audio generator, oscilloscope, AC voltmeter, and 4 ohm power resistor) tomeasureany of this?

author: DW1961
author_rank: Frequent Contributor
timestamp: August 17, 2020, 05:05:55 pm
content: Quote from: TimFox on August 17, 2020, 01:25:38 pmYou forgot knowledge to use the equipment, too.You've done more than necessary, Tim, and, I appreciate it. I understand if you no longer want to participate in this discussion. It's probably all really mundane for youIt just seems like there should be a way to deduce general power output given knows in the spec sheet/diagrams, driver, and resistance. We did that for one chip and came to some conclusions. It was easy after understanding the terminology they were using for "max" power, per channel, etc., which is confusing the way they worded everything--and confirmed by the thread at TI forums.Now I'm trying to figure out the same thing with another amp that uses x2 3116Ds.Still not understanding how they get any more power at 8 ohms using two chips, instead of one (which puts out 100 watts total RMS at 20V and 5 amps @ 4 ohms). That's pretty much the max behind the 24v / 5A power supply they provide.And, again, I'm talking about RMS not peak.I did get a reply back from the seller that said continuous power is 50 watts per channel at 8 ohms. I doubt it, since:8 ohms3.5 amps28 volts= 100 wattsI mean they are almost there, but it's a 24 v PSU, not a 28V. Max power for a 24V PSU is 72 watts at 8 ohms (Given the calculator).Just another quick question, and a quick, simplistic answer, that is bothering me and I've searched for it but no love: Why can't we decrease voltage and increase current (w/o changing resistance) when dealing with resistance in order to get the same power? I know it has to do with Ohms law, and the calculators for ohms and power do not allow trading volts for amps and vice versa, w/o changing ohms too.By a quick answer, I mean am I right about that? If so, if you want, you could explain it very simplistically. I don't need to know all the physics behind it. Just knowing that you cannot trade volts and amps w/o changing ohms around when dealing with resistance would suffice.

author: TimFox
author_rank: Super Contributor
timestamp: August 17, 2020, 05:56:27 pm
content: To your quick question: to change the ratio of voltage to current (i.e., the load resistance) without changing the DC supply and active devices, a transformer is needed to keep the same power. A "step-up" transformer will give more volts and less amps into a higher resistance, with the same power (ignoring transformer losses). If "N" is the turns ratio, thenV2/V1=N=I1/I2(note the opposite order for V and I),R2/R1=N2, andP2=P1.Solid-state designs avoid transformers, and are optimized for one load impedance, although they will function over a reasonable range of load. I remember a solid-state linear amplifier from 1969 that did have a manual switch on the power supply to change the optimal load from 4 to 8 ohms.Power amp specs are often un-trustworthy. RMS power is a misnomer for mean power (the M in rms).My question about your equipment was not an insult: I noticed that you had not replied to my suggestions for simple measurements. If you don't have access to or experience with such equipment, there's no further point in my suggesting measurement techniques.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 17, 2020, 07:04:13 pm
content: Quote from: TimFox on August 17, 2020, 05:56:27 pmI didn't take it as an insult. The best way to do this is like you suggested, get out the equipment an just test it, done! (And, BTW, test it for THD at different levels too, and the type of distortion, and all the rest!) I don't have that equipment nor the knowledge to run it.So when doing calculations with a digital power supply, like the power brick included with a class D amp, you get the amps and voltage that the equation spits out and that's it?If the power brick is 24v, and the amp needs 28V to get 50 watts per channel, how do you get 100 watts total RMS out of that amp using x2 3116D2 chips?So how can we tell what the power of this amp is, generally, at 8 ohms, without actually measuring it--don't we have enough information to guesstimate it pretty closely?Also, so it can put out 36 watts RMS x2 with two 3116D chips, it can do the same with one chip--so again, what's the benefit of two chips vs one chip at 8 ohms?

author: TimFox
author_rank: Super Contributor
timestamp: August 17, 2020, 07:30:44 pm
content: If you know the voltage and maximum current of the power supply, and you understand the mode of operation of the active amplifier and its losses, then they determine the optimal load resistance and the power into it. Usually, the power supply is treated as a constant voltage output with a maximum current capability, but the voltage will fall with higher current and excessive current could smoke the supply in a bad design.The details of that calculation are important, and you should consult the relevant textbooks. I have used Class-D, but am not an expert on your chipset.At the optimal load, the peak current (of the sinusoidal waveform) into the load (maximum possible from the circuit) will require the maximum voltage that the amplifier can put out. With a higher load resistance, the maximum peak voltage into the load requires less current and the power is lower. With a lower load resistance, the maximum peak current requires a lower peak voltage and the power is lower. Note the usage here of maximum (what the circuit can produce) and peak (what the load will do with the voltage or current supplied to it). In any of these three cases, if you try to exceed either the maximum voltage or current (whichever is hit first as you increase the signal), the output waveform will show clipping. Here, "peak" means the highest voltage (or current) in the waveform, half the "peak-to-peak" value.What complicates all of this is that it is usually uneconomical (for home audio use) for the DC power supply to maintain its voltage for a long time at the maximum current. Therefore, if you do a continuous measurement, the DC voltage probably "droops" after a short time and limits the power below that which could be delivered for a brief moment (as in normal music).

author: rsjsouza
author_rank: Super Contributor
timestamp: August 17, 2020, 09:58:23 pm
content: Quote from: DW1961 on August 17, 2020, 06:17:46 amSection 7.4.1 shows the PBTL (mono) connection.It is important to keep the nomenclature identical to the datasheet - in this case the authoritative source of information. You are correct the device internally has four amplifiers connected two-by-two in BTL that could be bridged yet again to form a single mono amplifier, to which the datasheet calls it "PBTL mode".Quote from: DW1961 on August 17, 2020, 06:17:46 amNope. As Kai's reply one2ealso clarifies, to get 100W RMS from one 3116D you can run it in BTL (stereo) at 4 ohms, which yields 50W per channel or 100W total, or in PBTL (mono) at 2 ohms, which yields 100W on a single channel. According to figures 14 and 22, you can get all this power using "only" 19V.Keep going up in voltage and you will get up to 170W from a single 3116D, either in BTL or PBTL modes.Quote from: DW1961 on August 17, 2020, 06:17:46 amWell, a resistor would consume 72W, which is equal to242/8, but that is where you need to consider the amplifier efficiency. The datasheettellsyou that 42W per channel is the maximum under these load and supply conditions. As TimFox mentioned, the amplifier will draw whatever it needs from the power supply - in other words, the power supply will passively provide whatever is within its limits, compensating with a reduction in voltage in case the amplifier consumes more than it will provide (thus clipping the output voltage).

author: cv007
author_rank: Frequent Contributor
timestamp: August 18, 2020, 12:57:06 am
content: >What is the benefit of running two of these when the power stays the same, and one amp chip is capable of putting out the same wattage using the same driver for both chips?You also have a set of mosfets that have to dissipate power (8x120 milliohm 'resistors', 4 active at a time). If a single ic is 'heat happy' putting out 50Wx2 (BTL, 100W total), then its probably also happy putting out 100Wx1 (PBTL, 100W total). Since there is a voltage limit, the only way to get to the 100W is by decreasing the impedance. The PBTL mode is simply a way to share the heat. Since there is no perfect mosfet, I imagine heat is the monster that lurks everywhere in the datasheet.If you are using 8ohm speakers, you cannot take advantage of the possible extra power (because of voltage limit), but you still get the benefit of sharing the heat among 2 ic's. That may mean you do not need a heatsink, or could mean the wimpy heatsinks used in an enclosed little case will not cause thermal shutdown.You need to look at any seller of audio gear the same way you look at laundry detergent that says '2x the cleaning power'. Its a waste of time trying to sort out the claims being made. Just look beyond the sales pitch, and look at the ingredients to figure out what you have.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 18, 2020, 01:43:54 am
content: Quote from: rsjsouza on August 17, 2020, 09:58:23 pm"Nope. As Kai's reply one2ealso clarifies, to get 100W RMS from one 3116D you can run it in BTL (stereo) at 4 ohms, which yields 50W per channel or 100W total, or in PBTL (mono) at 2 ohms, which yields 100W on a single channel. According to figures 14 and 22, you can get all this power using "only" 19V. "Yep, I failed to correct that statement last night. Sure, it says right there on the spec sheet a single 3116D amp will do 100 watts total at 4 ohms and 21 V. And, 100 watts mono at 2 ohms."Keep going up in voltage and you will get up to 170W from a single 3116D, either in BTL or PBTL modes. "Ok, yes, from one chip running at 4 ohms with 26V and 6.5 amps = 170 watts total.And we know that a single 3116D amp chip can put out 100 watts RMS at 4 ohms @ 21V (top of spec page).Using the chart on page ten for a single 3116D and 8 ohms and 26V, which is maximum voltage the chip is rated for:Approx. 85 watts total RMS at 26V @3.3A.My question is:Using two of these amp chips in PBTL mode for stereo, and leaving out efficiency factors of the amp package they come in, how many total watts RMS is it going to put out at 8 ohms using a 24V/5A PSU*? And, to my point, is to going to be anymore than using the same PSU with a single 3116D chip at 8 ohms?*Because that's what comes with the amp package.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 18, 2020, 02:06:48 am
content: Quote from: cv007 on August 18, 2020, 12:57:06 amYeah agree with all of that, for sure. That's why I originally started the thread.

author: rsjsouza
author_rank: Super Contributor
timestamp: August 18, 2020, 02:36:07 am
content: Quote from: DW1961 on August 18, 2020, 01:43:54 amTI did not seem to have characterized the device under these conditions, thus any conclusion is pure extrapolation based on the data.In this case, I would assume the relationship between figures 14 and 22 could also be applied to figure 13, that is: at 24V, power at 8 ohms in PBTL would be double when compared to BTL, thus yielding 42W * 2 or 84W (THD+N = 10%) - figure 13 shows 42W in BTL (stereo) mode when driving 8 ohms at 24V.Given the power supply can put out 120W, it is enough for a single 3116D operating in PBTL at 8 ohms at maximum output continuous power.Putting two 3116Ds in PBTL would requireat least168W + efficiency losses (about 87% or 88% according to the various graphs) - about 200W with safe margin or around 24V / 8.5A.Hopefully I didn't mess up my calculations.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 18, 2020, 06:24:20 am
content: Quote from: rsjsouza on August 18, 2020, 02:36:07 amRegardless of your calculations, I think you are saying the same thing I was thinking when I started this thread: How do you get any more power out of two chips vs one chip when the power supply only puts out 120 watts @ 0hms or 72 watts at 24v/8 ohms?"Given the power supply can put out 120W, it is enough for a single 3116D operating in PBTL at 8 ohms at maximum output continuous power."It cannot put that much power out when you add resistance: 72 watts @ 8 ohms and you run up against the PSU's voltage max, which is 24v. (If I am understanding this now.)It just seems like they can do everything with one chip vs two, especially since the amp package has a sub out for an active sub. I mean at 21V and just under 5 amps, you can get what they say at 4 ohms: 100 watts. IF you had ONE chip in the same amp package with a sub out for an active sub, you would still have the same power to play with given you are usually not going any lower than 4 ohms.But when they say you get 100 watts at 2 ohms, sure, if you have a PSU that puts out 7 amps at 14v.Again, the PSU we're dealing with is 24v/5A. That's all we get. It would be different is you had a 24V 10A power supply, then yeah, you would get a LOT more benefit form using 2 chips vs one becasue you would run up against voltage restrictions using one chip and would need two of them to put out more power.For instance, using a 26V power supply with a single chip, you can get max RMS at 8 ohms (according to the graph) and 3.3 amps of 86 watts. If you want more power at 8 ohms, then you need to use two of them. And, you would need to increase the PSU voltage (not necessarily the amperage) past 26V, which I assume could be regulated to each chip to not exceed 26V. Then, yeah, I can see the benefit of using two of them, but not with the same power supply that only puts out 24V.So the question remains, why build a dual 3116D amp with a 24V/5A power supply?

author: cv007
author_rank: Frequent Contributor
timestamp: August 18, 2020, 06:56:29 am
content: >In this case, I would assume the relationship between figures 14 and 22 could also be applied to figure 13, that is: at 24V, power at 8 ohms in PBTL would be double when compared to BTLYou are missing the fact that the PBTL graph is using 2 Ohms. All the graphs essentially end up the same (BTL 8,4,PBTL 2), each is just changing the load impedance to increase the power. PBTL is already BTL, its just parallel to share the heat.If you have 24v and 8 Ohms, it makes no difference if you run in BTL or PBTL as your total output will be the same. What you get, as I have said previously, is the ability to direct all the power into a single low impedance speaker if wanted. With 8 ohms and PBTL, all you get is less heat for each ic, which is a good enough reason and could be the main reason they run them in PBTL.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 18, 2020, 05:48:27 pm
content: Quote from: cv007 on August 18, 2020, 06:56:29 amSpot on for resistance. The only way an amp "makes more power" is either getting more voltage from the supply or lowering resistance so more current can flow to it. At least that's how I am understanding it currently."If you have 24v and 8 Ohms, it makes no difference if you run in BTL or PBTL as yourtotal output will be the same." Clear, and thank you.What I have been saying all along in this thread in one way or another, which is why I created the thread. I just didn't see the power benefit of using two chips vs one given the same voltage restrictions."all you get is less heat for each ic, which is a good enough reason and could be the main reason they run them in PBTL." ---Yo!, thanks.However, the single amp chip says it can run full out without any problems heat wise. If they really wanted to reduce chip heat, it seems like they cold do it a lot cheaper buy using a bigger heat sink or active cooling. Fans and heat sinks are a lot cheaper than the 3116D chip, I would assume, and less engineering too.The seller on Amazon wrote me back and said the amp package they offer with x2 3116D chips is 24V and anything higher will burn it. He also said that using the included power supply at 24V, you're gonna get 70 watts continuous power at 8 ohms. That's the same as a single chip, according to the graph on the spec sheet we've been referring to.I keep asking them why use 2 chips then? We'll see if they ever answer.

author: tooki
author_rank: Super Contributor
timestamp: August 18, 2020, 06:51:32 pm
content: You’re not going to get a reply from an engineer. Expecting a reply like that is an exercise in frustration.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 18, 2020, 07:21:44 pm
content: Quote from: tooki on August 18, 2020, 06:51:32 pmLOL, don't I know it! Well, when I review that product on Amazon and explain to people they are actually getting 70w atts RMS at 8 ohms, at least there's that. The seller actually admitted that in the public comments section, though.I tried one of these dual 316D amps before and it seemed like it put out more power, not at a static 8 phms, but just turning up the dial listening to music, it seems to have a lot more punch. No way to tell.The problem I had is that it was noisy when turning up the volume knob and with no music playing. It had a lot of hiss. My single amp 3116D unit does not have that. It's really quite. It was the same vendor's product.This new unit I'll test as well as I can tonight for hiss or any other artifacts. It's also a Bluetooth 5.1 receiver and as stated before, has a passive sub out for an active sub connection. I think this is where any of these 3116D chips could really shine, when you use the 3116D power to power mids and highs only, and use an active sub for the restHowever, you could do the same thing with a single chip and add a passive sub out to it.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 19, 2020, 06:03:07 am
content: I had an epiphany!Someone would have to do the calculation, maybe I will.But! I think I have figured out one benefit from using (2) 3116D chips.First, I just want to make sure my calcs are right about this included PSU. The included PSU for this unit is 24V/4.5A. That means the most power you will get with that PSU at 2 ohms is 40 watts total--lol? You need 10 A to get 200 watts at 2 ohms. Am I seeing that correctly?Anyway, here's my idea. Let's keep the voltage at 24V even though the specs say you can use 26V, and let's allow amps to be whatever they are. (Did anyone actually see an amp rating for these chips? I'm assuming it's 7 A because it needs 7 amps at 2 ohms in mono to make 100 watts.)You could wire (4) 4 ohms speakers in parallel and get 2 ohms or you could use (4) 8 ohms speakers at 4 ohms. Using a single chip, the most power you will get at 24V and 4 ohms is 100 watts.If you wire up 4-8 ohms speakers you get get a 4 ohm speaker system at 100 watts shared, or 25 per channel.FOUR SPEAKER SYSTEM4 0hms5 A20 V= 100 watts.25 watts per speakerTWO SPEAKER SYSTEM8 ohms3A24V= 72 watts36 watts per speaker.You lose 30% of your power, but you gain 100% more speaker. Just off the top of my head, you're going to make a lot more volume with the 4 speaker setup at 4 ohms than using 2 at 8 ohms (depending on speaker sensitivity).Am I far enough down the rabbit hole yet?

author: rsjsouza
author_rank: Super Contributor
timestamp: August 19, 2020, 03:25:48 pm
content: Quote from: cv007 on August 18, 2020, 06:56:29 amI am not missing anything. I am just using the output power characterized in Figure 13 (42-ish W for 24V in 8 ohms) and doubling it for PBTL, just like I did when extrapolating figure 14 to PBTL in 4 ohms (which coincidentally matches 2 ohms in PBTL).Oh well... Take it as it is. I would go with the manufacturer's specs and characterization curves instead of assuming that all is equivalent and equal.Good luck with your amp, DW1961. Peace out.

author: DW1961
author_rank: Frequent Contributor
timestamp: August 19, 2020, 04:41:38 pm
content: Quote from: rsjsouza on August 19, 2020, 03:25:48 pmRJ, you do realize that you were replying to cv007, right, and not me? Just wanted to make sure.

author: rsjsouza
author_rank: Super Contributor
timestamp: August 20, 2020, 12:59:56 am
content: Quote from: DW1961 on August 19, 2020, 04:41:38 pmYou are alright, DW. Everybody is alright, really; sorry for coming in too hard. New job, stupid quarantine and first day of virtual school with my twins takes a toll on one's patience.I hope the specs are clearer for you. Cheers!

author: DW1961
author_rank: Frequent Contributor
timestamp: August 29, 2020, 04:55:26 am
content: Quote from: rsjsouza on August 20, 2020, 12:59:56 amIt's all good. Yeah, I know now that there is no benefit from running 2 of those with their power supply. It's just all hype. I'd like to see some company do it right and use a 12A power supply to power both those chips to full power, though. Then you could get 50 watts per channel at 8 ohms, and 100 watts per channel at 4 ohms. Now we're talking some serious power.