Commercial Gainclone kit- building instructions

[Peter Daniel]

I tried Vishay 102 here and I didn’t like it. For 22k resistors, the best results are obtained with Caddock MK 132 and for 680R Riken or Kiwame

[mozarti]

Thank you, Peter!

[sthcoaster]

Just finished LM3875 Audiosector monoblocks.

[mozarti]

These are stunning! I noticed that you used Mundorf caps. What value did you use? Also, I am interested in your use of wood boxes, because I am thinking of upgrading my power supply by placing my transformers on a spruce board on the theory that vibrations will have a more pleasing resonance. Has anyone done such an experiment?

[sthcoaster]

Thanks

Had my wife's boss over for a meal the other night - he wants to commission a pair "exactly like them"

The Mundorf caps are 1500uf 100v. 22k Resistors both MK132s and 680R is Kiwame as per PD's preference.

I've not done any component swapping.

The front badges are antique Chinese coins with a faux jade bead cut in half and led mounted behind. On account of these being finished around Chinese New Year I'm calling them Metal Ox (even though they are largely constructed from wood).

At the moment they are naked on the underside - so no putting the fingers in there please!

Noticing details in the mid range that I don't think I'm hearing when my ancient Chord SPM900 is in use.

I can't comment on resonance properties of wood etc. It's just what I have available to me and I'm happy with how they worked out. The 50mm teak + the 300VA R-core transformers add up to a satisfying weight.

Originally Posted by mozarti

These are stunning! I noticed that you used Mundorf caps. What value did you use? Also, I am interested in your use of wood boxes, because I am thinking of upgrading my power supply by placing my transformers on a spruce board on the theory that vibrations will have a more pleasing resonance. Has anyone done such an experiment?

[sthcoaster]

So I have a little niggle with the new mono blocks. Doesn't effect their operation but it bugs me.

Monoblocks are meant to be the same right? But when I turn them off, the led on one turns off immediately, the other fades over time.

Before I go back inside to see what/anything is physically different, which one is exhibiting the correct behaviour? Off immediately or fade?

[mozarti]

I have two questions about the snubber implementation that I hope that one of you can address. Currently on my rectifier board I have a 6800 mf caps which are bypassed by 10 mf blackgates. I was thinking of adding a snubber. Two questions:

1. Peter mentioned that for the snubber the cap must be at least 10000. Is 6800 close enough? And why is it important to have a really big cap?

2. Do I need to remove the 10 mf cap if I want to put the snubber? The placement of the resistor is not a problem as it can go over the cap without touching it.

[Peter Daniel]

The snubber was actually a solution to a really big cap. The gainclone amps were usually using rather small caps in a range of 1000-2000uf because that created good sound with well defined and controlled bass.

Some people started complaining that with hard to drive speakers they couldn’t get enough bass so they started adding more capacitance, but that didn’t sound good. And then, one guy figured out that by adding snubber, he can make large caps to sound good as well.

So, 10000 or 6800uf doesn’t make any difference here. Try the snubber and see for yourself if you like it or not. You don’t need to remove 10mf cap neither, listen with and without cap and see what you like better.

[mozarti]

Thank you so much, Peter!