• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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ruffrecords

ruffrecords

Member
Joined 2007
customtubeconsoles.com
kodabmx said:
That's quite a nice build, right there! Is it actually modular or does it just look that way?
Click to expand...
Yes it is modular. Here are some pics of the PCBs. First the channel module (mic pre, EQ and routing):

Channelith-EQ.jpg


Then the channel module PCB as a completed module (several views)

Channel-Module-R.png


Channel-Module-L.png


Channel-Module-Top.png


The completed four channel module PCBs (there is room for 6 in the mixer)

Channel-Modules.png


and lastly the complete set of PCBs for the mixer (channel amps, mix amp, VU buffer amp and monitor section transformer PCB)

PCBset.png


Cheers

Ian
 
ruffrecords

ruffrecords

Member
Joined 2007
customtubeconsoles.com
kissabout2002 said:
Congrats Ian is a BEAUTY !!!!!!! What are the advantages on use tubes rather then solid state component on mixers? ....all the best
Click to expand...

Good question. When I worked at Neve back in the early 70s, all their designs were class A and their sound is revered today. Once ICs came along, everything changed to class B and the sound changed.

All my designs are class A so they have the same advantage in sound that the Neve designs of the 70s had. An added advantage is that they create less distortion than the equivalent transistor circuit so they need a lot less NFB
and their overload characteristic is much gentle. Add this to the fact they have enormous headroom due to a 250V supply rather than a 24V one and the answer is they sound simply sublime.

Cheers

Ian
 
N

Nectarpuke

Member
Joined 2011
The schematic for interested parties. The parafeed capacitor will have to be tuned to the headphone impedance. Also it should be noted that the transformer may not be suitable for all headphones. A lower turns ratio may be in order for less sensitive cans than my AKGs.
 

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jamesfeline

jamesfeline

Bespoke Constructor
Joined 2006
Paid Member
Diabolical Artificer said:
Line level Preamp and PSU for a Phono amp using the CCDA circuit as recommended by Coda and others.

PSU is 330 0 330v 60mA mains tmr, first cap 2 x 220u in series, 10H choke, then 820u 400v cap in parallel with two VR150/30's - HT 1 309v. HT two after 1k5 R and 50u cap each channel 288v.

Valves 2 x 6H8C. Tried LED as V1 bias, got better balance with resistor. All values the same - ish apart from 300r = 310r, 430r = 470r, I used what I had. Consequently each channel running at 14mA instead of 20mA, this is better for my mains tfmr too.


There's a few minor bits to do, like labels, EG PC, CD etc, better knobs and I have to find some screws.

well done from me ... very impressed

Andy.
Click to expand...
 
A

Alexgsxr

Member
Joined 2017
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