heaving hard time picking a amplifier - Page 1
Forum section: electronics / beginners

author: DarkZero
author_rank: Regular Contributor
timestamp: May 06, 2018, 10:00:06 am
content: Hello all !i have speakers that i want to hook up to a amplifier now the problem is on the back it says 15W 6ohmsbut when i opened them up i saw one speaker of 12.5W and paralleled to it 5W both at 6ohms and 2.2uF cap in series with 5W speaker now my question is if i hook it up to those 15W Chinese D class amps and put volume on highest wont the 5W one blow up ?

author: Brumby
author_rank: Unknown
timestamp: May 06, 2018, 10:35:43 am
content: It should be OK. The capacitor is a simple high pass filter for the smaller speaker - the tweeter - and it effectively reduces the lower frequencies from getting through and, by doing so, reduces the total power to reach the tweeter.Lower powered tweeters are common. You only need a smaller amount of power to produce a balanced sound.

author: Twoflower
author_rank: Frequent Contributor
timestamp: May 06, 2018, 10:37:05 am
content: No worries. Just use a 15W amp. The cap in series with the 5W speaker will reduce the power for the tweeter to a correct power. And by the way. If you don't play at full volume you don't drive the speaker with full power.It is often said that the amp should have actually higher power than the speaker. Because if the amp clips (start to distort the signal) the resulting high frequencies might kill the tweeter. On the other end you notice if you drive the speaker with a too high power with a too big amp: You hear it and if you didn't overdid it you can reduce the volume without any harm done. So you can easily use a 50W amp with that speaker if you don't turn up the volume too high.

author: wraper
author_rank: Unknown
timestamp: May 06, 2018, 11:12:34 am
content: Quote from: Brumby on May 06, 2018, 10:35:43 amIt's not just common but how almost all speakers are made.

author: Zero999
author_rank: Super Contributor
timestamp: May 06, 2018, 12:48:08 pm
content: It should be fine in this case, as it's a dynamic tweeter, i.e it has a voice coil.If it were a piezo tweeter, then this could cause an issue, with a class D amplifier without much filtering, because its impedance will probably be low enough to allow a high current to flow, at the switching frequency.How do I know it's a dynamic tweeter? It has a magnet on the back and a capacitor in series with it, which wouldn't be required for a piezo tweeter.

author: DarkZero
author_rank: Regular Contributor
timestamp: May 06, 2018, 03:45:53 pm
content: that a nice info on piezzo !so i wana check something here so 2.2uF and 6ohm makes a 12khz high pass filter so anything above that frequency will pass unchanged so how does it not fry that little speaker or i have to take the inductance of the coil into the account ? if i misunderstood anything i just want to learn.

author: wraper
author_rank: Unknown
timestamp: May 06, 2018, 11:48:42 pm
content: Quote from: DarkZero on May 06, 2018, 03:45:53 pmBecause there is no music which consists mostly of such high frequencies. If you put 15W 12kHz sine into speaker, it sure will hurt your ears to begin with.

author: Brumby
author_rank: Unknown
timestamp: May 07, 2018, 01:04:38 am
content: As I said before:Quote from: Brumby on May 06, 2018, 10:35:43 amandwraperis quite correct. 15W @ 12kHz will be well past torture levels if you are in the same room with a tweeter of even moderate efficiency.