Commercial Gainclone kit- building instructions

[Peter Daniel]

Originally posted by gychang
I will be following this thread, but I get confused on the transformer to get about 55W/ch in stereo from GC.

Anyone know the website for the appropriate transformer?, need cost-effective solution for the classic GC kit from Peter.

Any of the model here work?
http://www.apexjr.com/miscellaneous.html#Toroids

or here:
http://www.partsexpress.com/webpage....e_ID=3&x=0&y=0

do I need one or 2 transformers. (please say 1 )

gychang

Partsexpress is more suitable choice. Go with a single Avel 250VA transformer, either 2 x 25V for 8 ohm speakers, or 2 x 18V for 4 ohm speakers.

I will post tomorrow more info how to wire single transformer.

[Colin]

For UK Gaincloners, this Airlink transformer is a good substitute for the 300VA Piltron. Kensai (I believe) recommended Airlink on another thread. I received my Airlink toroid earlier this week and it seems a very solid unit. One offs are about £32 including delivery.

[gychang]

Originally posted by Peter Daniel


Partsexpress is more suitable choice. Go with a single Avel 250VA transformer, either 2 x 25V for 8 ohm speakers, or 2 x 18V for 4 ohm speakers.

I will post tomorrow more info how to wire single transformer.

My speakers are 8Ohms.

Is this the right one, I only need one right?
http://www.partsexpress.com/pe/showd...number=122-625

I will be looking forward to your instructions.

gychang

[Peter Daniel]

Yes, Avel Y236652 250VA 25V+25V Toroidal Transformer is right choice for 8ohm speakers.

If you don't mind spending a bit more, Avel Y236750 330VA 25V+25V is a good choice too.

[Bluto]

Hi Peter -

My boards just arrived about an hour ago. The quality is very impressive. Thank You again.

How many questions do you want here on list vs. via PM?

I already have several 'dumb newbee' ones myself.

Bluto

[Peter Daniel]

No problem with all the questions in here.

[Peter Daniel]

Originally posted by Peter Daniel
This concludes the assembly and we have two separate amp channels with separate bridge rectifiers. All is needed now is to connect 2 transformers (one per channel) as per schematic posted here: http://www.diyaudio.com/forums/attac...amp=1210694958 , connect the input (SG for ground, IN for signal input) and output ( OUT to positive binding post, OG to negative) and we have a working dual mono amplifier.

And this is how one complete amp channel looks when wiring is done. The transformer primaries are not connected yet, and I will explain it at later stages.

I usually use 26ga solid core wire for input signal and I never found a need for shielded cable. I normally don't even twist them, but it's a good idea anyway.

For speaker connections I use 19ga stranded wire.

See this table for American Wire Gauge Table:

http://cc.msnscache.com/cache.aspx?q...b17&FORM=CVRE2

[Peter Daniel]

Those are some tools you may find useful for wire insulation stripping:

[Peter Daniel]

By stereo version I mean the use of a single transformer powering both channels. You could still use two separate rectifiers boards, but depending on wiring it may produce hum in some systems, so I always stick with a single rectifier board when using one transformer.

For demonstration purpose, I will install all the boards inside 3 x 1.5" U-channel, 1.25" aluminum extrusion. For normal listening, this is enough to dissipate heat from the chips, and when things get hot, you can always attach it to larger aluminum panel.

I will show a version with a potentiometer, and without, so stay tuned.

[rfenergy]

Hello Peter,

Great thread.

My buddy just ordered 2 3875 classic kits last week. I will be the builder. One kit for my studio monitors and one kit for his home stereo.

Can't wait for the rest.

I will be building 2 stereo versions.

I also had a question about internal wiring of the inputs/outputs and passive pot.

I use mogami 2549 mic cable it is OFC 22 gauge shielded.

DC Resistance
Inner Cond. 0.058W/m(0.018W/Ft)
Shield 0.013Ohms/m(0.004Ohms/Ft )

Capacitance at 1kHz, 20°C
K0 76pF/m(23pF/Ft)
K1 11pF/m(3.4pF/Ft)

I use this for all my interconnects and mic cable in my studio.

Would this be ok/good to use for the input and output (and pot) wiring?

Out,

Robert

p.s. you have amazing machining skills.