*** The DIY Audio Thread ***

for the dac or valve amp?

dac - the chassis is grounded, the signal ground goes to the earth tab on the IEC. Try it with an alligator lead.

Valve amp:

yes, star ground is a bolt thorugh the chassis (with continuity) and everything going to this point.
 
What's an IEC...?:o

So there's no problem in having the signal ground connected to the chassis, which is earthed to the mains earth?

edit: do your RCA connectors actually need to be isolated from the chassis then? This is why I'm getting confused! :p
 
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ChrissyT88 said:
@p4radox - mm.. definately learned from it... pain because it wasnt particularly cheap and took ages to get here. Still, once bitten... (well, hopefully that will hold true!). The worst thing was the smell - i could not get the smell of burnt silicon/copper/pcb out of my nose for hours.. a constant reminder that i messed up! Im really annoyed that i did it - i should have just left it alone - but its too late now...

@damian - cheers for the quick reply. Im thinking about giving one a go - as you say, they seem quite cheap when buying bits from america. Did you use all the stock parts from chipamp or did you do a recap?
Click to expand...

All stock, im not gonna bother upgrading this one, ill leave that for my next project which is the lm4780 ~(2x lm3886 in one ic)
 
p4radox said:
What's an IEC...?:o

So there's no problem in having the signal ground connected to the chassis, which is earthed to the mains earth?

edit: do your RCA connectors actually need to be isolated from the chassis then? This is why I'm getting confused! :p
Click to expand...

Technically no, which is odd. connecting to the earth line was the only way i could cure all the noise. And it works on every amp i own.

IEC http://en.wikipedia.org/wiki/IEC_connector
 
Right, some good news at last. My AMP10 Basic works perfectly, first time. Not a single problem apart from some thump on the outputs at shutdown.

It sounds... brilliant...

I'm just experimenting with the input caps. By default they're 3.3uF electrolytics, but I've put one channel as a spare 2.2uF polypropylene that I had lying around. The poly is much, much clearer, but lacks the clout at the lower end that the electro has. I think I'll end up with the polys to be honest, unless anyone can suggest anything else? Blackgates?

edit - I'll salvage some polyesters from my defunct AMP10 to try too.
 
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p4radox said:
Right, some good news at last. My AMP10 Basic works perfectly, first time. Not a single problem apart from some thump on the outputs at shutdown.

It sounds... brilliant...

I'm just experimenting with the input caps. By default they're 3.3uF electrolytics, but I've put one channel as a spare 2.2uF polypropylene that I had lying around. The poly is much, much clearer, but lacks the clout at the lower end that the electro has. I think I'll end up with the polys to be honest, unless anyone can suggest anything else? Blackgates?

edit - I'll salvage some polyesters from my defunct AMP10 to try too.
Click to expand...

Great news! whats the main differance of the Amp10 & Amp10B?
 
AMP10b has an output relay to protect speakers. It also has ready-made encapsulated inductors and fewer bulk caps. Everything is more spaced out, but the PCB is the same size. Overall it's much better to be honest.

The DAC works perfectly with it too. :)
 
Nope, it's still bridgeable. Seems like a better amp in every way really, I don't know why I bothered with the vanilla AMP10 the first time...
 
Good point Adam. I'm not actually using the DAC's output stage, but I've got zero offset on my own output stage anyway.

Out they come.:)
 
I isolated my whole heatsink of the amp9b in the end, using big plastic washers (from banana plugs) and lots of tape around the screws thread. Works like a charm:

imgp1612jd5.jpg


One thing I think I've wired up the speakers inputs wrong as
1 in = 4 out
2 in = 3 out
3 in = 2 out
4 in = 1 out

It also sounds very strange when I listen to the speakers off axis, I think they may be out of phase, I'm only using 2 channels right now.

Still, this can be sorted with some experimentation... I'm just glad to have have eliminated the noise and have this thing in a chassis. There is also enough room for the DAC but I think I'll put it in another box as it will be really cramped in this one.
 
Mike, any chance of a closeup of the heatsink? I'm not clear how you managed to get thermal contact without making electrical contact...
 
p4radox said:
Mike, any chance of a closeup of the heatsink? I'm not clear how you managed to get thermal contact without making electrical contact...
Click to expand...
Adam W said:
I assume he means there is plenty of contact with the chip, but the isolation is between the case and heatsink.
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Yep, Adam is right, the heatsink isn't isolated from the Tripath chip at all. I've just kept the heatsink away from the chassis do there is no electrical connection between the two.

Piccy:
imgp1611nr9.jpg
 
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