valveaudio PCBs

[metal]

Hi,

I have seen this amplifier http://members.tripod.com/valveaudio...atics/200w.JPG any one has bought the PCBs from david and tested it ? Any opinions about the circuit, is it really a 200 watts amplifier ?

[metal]

strange, no comments

[Sonusthree]

I can't see the picture. I've tried Firefox and IE 7.

Sorry, but the page or the file that you're looking for is not here.

[Francois G]

Originally posted by Sonusthree
I can't see the picture. I've tried Firefox and IE 7.

Me too!

[metal]

Strange thing, When I open it from its homepage 200W POWER AMPLIFIER , it works

Here is the schematic.

[h_a]

Strange thing

Yeah that also applies to that amp. 200W for a single output pair? That the output power into 8 Ohms is only 50W smaller is already telling.

Otherwise it's a fully complementary topology, which is in principle nice to see.

That amp with lower rails, say +-35V, could be a nice toy, however using a single output pair would give me enough reason to look out for other oddities as well.

Have fun, Hannes

[metal]

other oddities?

Tell me more, more

[h_a]

Oh I meant to check currents for example (LTP, VAS, drivers) that are maybe also chosen 'unconventionally'.

Just by having another short look at the parts list a few other things catch the eye: the amp uses hard to find parts, like the Hitachi 2SB649/2SD669 - sure there are clones by other manufacturers - but as far as I'm aware of - of less quality. As the MJ15003/4 as output is used I would maybe choose a more high power driver as these bjts can vary in beta as low as 25 which makes the driver work very hard.

Next, pcb-layout will be a bit critical as 5pF are used in the compensation which is already on the level of pcb-parasitics. But you're anyway interested in buying pcbs.

Otherwise I'm sorry but I don't have the time to finely dissect this amp, if you're interested in building it, just go for it. Building is the most fun

It's maybe not something I would build, but I guess it will do.

Have fun, Hannes

PS: alternatives would be the Quasi, Lynx, Leach, Symasym - for many of these you could try to get a pcb here in the group buy or trading section.

[metal]

I think I will go for the LYNX amplifier. There is no group buy for the Quasi Bp300.

Thanks