ASL wave 8 monoblocks

[Saurav]

I removed the "bell" or "end" caps from the output and power transformers.

That's a new one for me. Can anyone else comment on this? Does it fall into the "controversial tweak" category?

I know that the PSU caps in my amps were different values from what's shown in the schematic. Also, the schematic says 0.5W resistors for cathode bypass, but the ones used were quite a bit larger. So at least in this case, the actual amp was better than the schematic would indicate.

I haven't tried rotating the transformer because that would involve drilling new holes, and I don't want to hack into these amps too much so that I can have some hope of selling them.

The cathode bypass caps are 100uF electrolytes, I'll try adding bypass caps to them tomorrow.

 

[Joel]

Does it fall into the "controversial tweak" category?

To say the least. I think it falls into the too-dumb-for-words category myself.

 

[JBasham]

As you may have read before, I advocate putting Bottlehead's C4S boards on the plate of the driver triode in these amps. I think they cost $35 a pair. You only need one pair. R1 on the boards will be around 3.3K, but measure your voltage before and after to be sure.

Oh, also I seem to recall the filaments are biased up -- they're routed to ground through 1K resistors that might not be on the schematic.

So far I can't get hum & buzz on these any lower than about 2 mv (shorted input and unloaded). I haven't put snubber caps on the filament bias resistors or the filament pins yet. I might try rectifying the filaments. The mnfr. told me there's enough current available on the filament winding.

 

[fdegrove]

FILAMENTS.

Hi,

I might try rectifying the filaments. The mnfr. told me there's enough current available on the filament winding.

The current requirement for A.C. or D.C. is the same.
If you go D.C. I recommend regulating the volatge too.

Cheers,

 

[JBasham]

Sorry, I was under the impression that the tubes will draw the same filament current regardless of whether they're fed AC or DC, but that the rectifier will consume current in the process of converting from AC to DC before it gets to the tube?

 

[king30]

Here are some mods found on AA which may interest you.

http://www.audioasylum.com/audio/tubes/messages/60782.html

http://www.audioasylum.com/audio/tubes/messages/81187.html