One channel is louder than the other?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
All the resistor values are correct. I don't have the ability to test the caps (1500uF) due to the fact my DMM only goes to 20uF, but the polarity is correct as far as how they are mounted. The one thing I noticed as far as the board is concerned is the fact that the feedback resistor isn't soldered all that great...I was going to try and re-solder it in a bit.

Also, it doesn't seem like there is a lot of distortion or problems with the outputted sound...it is just substantially softer.
 
I don't think it's the chip. They work or they don't. The gain of the chip is controlled by the feed back in the circuit. The only thing that can cause this channel to be different from the other is:

1. A different feedback ratio (resistor values or short)
2. More loss in the input circuit (resistor values or short)
3. Lower input impedance loading down the source (resistor values or short)
4. High impedance output circuit (solder joint or bad speaker ground)

If it was the chip there would be a lot of distortion.

Later BZ
 
I had the similar problem, but it is on my left channel. I sloved it by touching the pin 1 of the chip while I am measuring the feedback resistor and pin 1 and the amp is running. However, I will suggest you to resolder the components instead. Check for shorts, and make it clean (tips : you can clean each solder joint by whiping the joints with
rubbing alcohol, then you will have a shinny joint with no yellow stuffs on it.) Rmember Safety first !
 
I'll take a look at the solder points again tonight. As for the source, it's good up until the pot I have installed. I've been systematically going through the path from input to output trying to find the problem area, so hopefully it'll jump out soon. Thanks for all the input so far!
 
This may not be a safe method to test things up, so I am going to warn you first. and Resolder will have the same effect as follow, so don't try it if it is unnessary. If you do try it wear safety equipments like googles, gloves, and not your sleeping clothes.

Ok. Since my left channel sounded different from my right channel, I went though the whole thing again. There were no short, wrong connection, components in wrong place, and the PSU was fine. I kept it on and moved the enclouse a little bit for better vision inside of the amp. The left channel suddenly came clear. Then I knew there was something loose in that channel. I tried to push the board softly a couple times, but the channel still didn't work. Then I use my meter to check the voltage between input, caps, V+/-, PG+/-, and finally the chip pins to look for the differences of the right channel and the left channel. Then I start the mearsurement on Pin 1, and move up one at a time. Suddenly there is a small spike between 1 and 3 where the feedback resistor is. After that, the amp running fine untill the recent explosion of my cap, but it had nothing to do with this solving method. It is quite not safe to do that kind of measurement, cuz you are shorting stuffs I think. So I suggest u just to resolder the join instead. :cool:
 
I went back through and was looking at the board(s) again, and I came across something after staring at it for a long while....both R1 and R2 are 220ohm, instead of R2 being 22kohm. Seeing as how I am using a 50k pot, I think this might be causing the issue. Does this make sense?

That's what I get for not knowing my decade colors as well as I should!

I think you may have been right BZ...check my values...:bawling:
 
ble0t good job. That will do it every time. Missreading the color code is easy to do so don't feel bad about that. Finding it should make you feel good. Add see that? The rules do work. Circuits do work the way they are built even if we think we have built something else.

Later BZ
 
HDTVman said:
Missreading the color code is easy to do so don't feel bad about that

It certainly is very common, particularly with 1% resistors. They may even come mismarked, though that's very rare.

In any case, in amplifier projects such as this, it pays off to buy several equal resistors and pair them, if possible using a tag saying the value. That should prevent such problems as yours and also to be sure both channels are twins.

That should be a demand if you are paralleling amps.


Carlos
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.