| Nuuk |
I'm measuring 113 mV DC offset on one channel of the AMP-3 that I have here. The other channel measures 10 mV.
Is this normal for the AMP-3? And how safe is it to connect the amp to some speakers? :xeye: |
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| jkeny |
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 |
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| Nuuk |
Well that makes my 113 mV sound not too bad John! ;)
I think I am correct in saying that Leo managed to desolder a chip from his AMP-3 and replace it with another one!
Isn't the chip in the SI amp the 2024 though? The AMP-3 chip is the 2021! :att'n: |
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| t. |
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 |
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| t. |
Good Timing Nick:D
BTW you are correct, the chips are different |
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| jkeny |
Oops,
Thanks guys - anybody know where 2024 chip is sold - SI board has thiis chip sitting on solder slug - this might make desoldering it v difficult
John |
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| sx881663 |
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 |
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| t. |
Hi Roger,
What sort of DC offset do you get on your Amp3?
Cheers |
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| sx881663 |
| quote: | Originally posted by t.
Hi Roger,
What sort of DC offset do you get on your Amp3?
Cheers |
79 MV on one and 67 MV on the other, not great but passable.
Roger |
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| BWRX |
| 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. |
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| t. |
| quote: | Originally posted by sx881663
79 MV on one and 67 MV on the other, not great but passable.
Roger |
Thanks Roger,
Seems yours is similar to mine
It makes me wonder though why the DC offsets are higher than normal |
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| t. |
| quote: | Originally posted by BWRX
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? |
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| BWRX |
| nope, no mods. although i did use 0.6mm wire instead of the supplied 0.5mm wire for the toroids. that shouldn't make much of a difference though. |
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| Nuuk |
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! ;) |
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