• 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.

Poll..anyone interested in an Aikido linestage PCB group buy?

Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
This is just a preliminary check.


First of all we would have to ask John Broskie's permission.

Secondly I don't think I should be running the groupbuy because to prevent any confict of interest (being a moderator).

Thirdly it is not such a cheap design since it uses tubes and 4 of em...with the added cost of 4 or 5 tube sockets...filament transformer etc.

But it is imo a great design...sounds very good. (I finished mine a week ago)

But there might not be a lot of consensus on tube types/tube rectification vs solid state..

I know that there is possible group buy going on for the grounded grid by Rozenblit...but am curious as well how many would rather try the Aikido?


Aikido design can be found at www.tubecad.com
 
No I haven't built one, but it's a definite possibility in the future. I like elegance expressed in the general concept. First, I've gotta finish my speakers (Unity Horns, destined to be quade amped) and the amps for them. Then it's a pre/buffer, then a phono stage. By the way, those amps will be based on a Steve Bench design that uses another noise cancellation technique - electronic redirection (or Aikido, if you will). I already have some spare amps and stuff, so one component more wouldn't hurt. I build partly for my main system and partly to learn and I will give the extras to interested family or friends after I pick the ones I will keep. If a pre board were relative inexpensive I'd buy one just to prototype up a unit.

Sheldon
 

Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
It doesn't have to be twin triodes.

Any matched pair of triodes can be used as one of the Aikido pairs and get the Aikido advantage. See JBs use of EL34 trioded as Aikido output stage.

One can also build a pentode or cascode input Aikido - again see JBs articles. But the full Aikido advantage is from using triodes.

James
 
James D. said:
It doesn't have to be twin triodes.

Which begs the question "can a PCB layout be made that accepts different pinout tubes?". Seems to me that it wouldn't be so difficult, what with needing grid stopper, biasing, etc., resistors right at the socket anyways. I like the idea of buying more than 1 PCB and trying variations like dual triodes, strapped pentodes, etc. Just thinking out loud, I don't know if it would work well on a board....
 

Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
I am not sure how you can accommodate different socket types.
Nor am I. I must admit I had already given up on the idea.

One way would be to just add holes in the pcb for wires...that way anyone can wire up their sockets. The heater supplies will just lead up to the sockets and could be connected via jumper wires to the appropriate pins. OTOH one could just leave the heater wires off..but that might lead to hum if not done correctly..maybe best would be to do DC conversion/regulation on board?
 
Well, my $0.02:

When I mentioned accomodating different pinouts, I was thinking of maybe committing to 1 socket, nonal, and then having gaps between the socket pads and the balance of the circuit that would require either the stopper resistors, bias resistors, or plain jumpers to complete the circuit. This could be done in a way so that 1 board would make a stereo pair channels using dual triodes, and just 1 channel for a pentode.

The issue of heater wiring and hum sounds tricky, but you probably need to leave a way for someone who wants to use AC to bring twisted wire right up to the socket. Yes, a DC section for heaters sounds very nice too.
 

Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
bonny_kjs has offered us help. He could make the PCB and would offer the boards for cost and shipping (as a groupbuy requires)

I'd be interested since a pcb cad learning curve alone would take me a while..getting the right shapes etc. especially.

Here's a sample of his previous work :
 

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Bas Horneman

diyAudio Moderator Emeritus
2002-04-03 12:03 am
The Netherlands
Hi Johnny,

Great! The more the merrier...It might take a while though. I have this feeling that we are going to have some good arguments settling on the final design.

Let me start by asking a few questions that need be answered or come to mind

1.) PSU or no PSU on PCB?
2.) DC current regulation only? or even onboard filament "stuff" or not?
3.) Fixed socket type or no?
4.) Safe version or not?
5.) Pot included to tweak the 50% psu injection into grids (see improving the Aikido thread)
6.) Width control added or not?
7.) Tube rectification or not..my preference is for Hybrid Graetz bridge

Regards,
Bas