Soldato
Don't worry, I'm not going to use it again until I've got it in a case. I'm just glad it was just a jolt and nothing worse. 
*** The DIY Audio Thread ***
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Soldato
Adam, you mentioned that you use your case as a star ground. Is it also earthed via the mains cable?
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.
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.
Soldato
What's an IEC...?
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!
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!
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Soldato
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)
What's an IEC...?
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!
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
Soldato
Yeh its a very successful trick for the gainclones.
Soldato
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.
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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Soldato
Great news! whats the main differance of the Amp10 & Amp10B?
Soldato
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.
The DAC works perfectly with it too.
Soldato
Thats great news, can the 10B still be bridged or is that out of the feature set as well?
Soldato
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...
Soldato
Actually, it's not bridgeable, my mistake. I was reading the TA2022 features rather than the amp spec.
Soldato
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.
Out they come.
Soldato
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:
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.
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.
Soldato
Mike, any chance of a closeup of the heatsink? I'm not clear how you managed to get thermal contact without making electrical contact...
Soldato
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:
