AMP-3 DC offset (high)

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I had 149 mV dc offset on one channel of my SI amp(other channel was 10mV) and it was ok connected to Rogers speakers although a slight bump was heard at power on.

I had another SI amp with low dc offsets on both channels < 20mV, which was going to be my preferred amp but I blew the chip experimenting with output inductors when OUTM1 & OUTM2 connected while running.

I'm hoping to order a chip (from 41Hz?) and try to desolder old and solder in new - has anybody had success with this operation?

John
 

t.

Member
Joined 2003
My Amp3 also has 70/80mV DC offset both channels.
So I wonder whats causing this:confused:

I have just replaced the TA2021b chip in my Amp3, unfortunately it isn't easy but is possible, just make sure you take your time:)
I didn't know 41hz sold the chip suitable for the SI amp
 
SI repair

I would have to say forget repair unless you have access to a modern facility with all the correct hardware. Even then it would be a coin flip. The board is extremely fragile and can be easily ruined, this is experience speaking. This is not the quality found in the amp3.
Roger
 
Ex-Moderator
Joined 2005
i had 3.2mV and 11.7mV on my working one (with no source connected) and 0mV on my non-working one :mad: one thing i do notice is that even though the dc offset is low and there is no noise coming from the speakers when no source is connected there is a lot of noise when a source (ipod, cd player, computer, etc.) is connected. do any of your AMP3's have the same issues with noise? it's much worse than compared to even a stock SI which has very little even with a source on the inputs. i don't think it's the source because the noise level is about the same with the three different sources i listed above.
 
BWRX said:
i had 3.2mV and 11.7mV on my working one (with no source connected) and 0mV on my non-working one :mad: one thing i do notice is that even though the dc offset is low and there is no noise coming from the speakers when no source is connected there is a lot of noise when a source (ipod, cd player, computer, etc.) is connected. do any of your AMP3's have the same issues with noise? it's much worse than compared to even a stock SI which has very little even with a source on the inputs. i don't think it's the source because the noise level is about the same with the three different sources i listed above.

Mines silent when I plug in either of my diy dacs but there is a small bit of hiss If I plug in my dvd player but I think thats just noise on the dvds output.
Have you modded your Amp3 at all?
 
I got brave today and connected the AMP-3 up to a test speaker. No problems with the 120 odd mV offset so I tested the other channel and then connected up my 'proper' speakers'.

After all the angst of not completing the kit first time (thanks again to Leo who 'sorted it') I am pleased to say that I like what I hear. But that's all your getting out of me at present! ;)
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.