• 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?

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#723
Thanks Bas.

How about a tube recommendation? This is my 1st tube project and I need to pick the tubes.

I'd like, in order of preference

1. Low distortion
2. Low noise
3. readily available
4. minimum of mods to the boards and power supply.

I generally like accuracy/ low distortion vs. bloom and sweetness if thats any help.
 
#725
Input Capacitor /Mundorf Silver-in-Oil and Mundorf Silver-in-Gold

Hi JLH diyer,

Is there anyone using Mundorf Silver-in-Oil and Mundorf Silver-in-Gold and Jensen Copper-in-Oil for the input capacitor?

What is the quality sound of High End, Mid-Range & Bass?

Which one is better?

Best regards
Dominic Ko
 
#726
Anybody built John Broskie's 24V 6GM8 version of the Aikido using his 9-pin board (or Bas's)?

Could be a killer since both Welborne Labs and Wavelength Audio have made superb preamps using the tube with battery power. Of course, they are totally different circuit topologies, but they do prove this tube has reference level potential.

To take that one step further, why not make JB's fully balanced Aikido using the 6GM8?

So, my real question is if it would be better to make a a fully balanced version using a single stereo or 2 mono boards for each channel?

I'd like to add an optional Aikido balanced preamp to my TVC.

Any advice greatly appreciated.
 
#729
Anyone still around?

RV1 I think is the 100k input pot. RV2 is noise trim?

Anyway, I am putting an BAS/Aikido together and would like a 12AU7/5687 combo.

The heater connections would be straight up 12VDC on pin 4 and 5 on both tubes. Jumper 7 is disconnected

Anyone done this combo? How about what the output impedance would be?
 
#731
I have a new pair of 6N1P, and just may use it with the 5687 output.

I also have a "Hot Silver Top (?)" 12AU7 pair. Don't know the history on it, but I was given the tube and it sounded really good on my Bottlehead FPIII. The FPIII had way too much gain, so I reluctantly sold it (and it was subsequently destroyed by UPS), but I always really liked the sound. I always thought the 12AU7 was a good tube compared to the 6922 or 6N1P.

Anyway, I found the 12AU7s the other day and looked into using it on the Aikido.

If I use the 6N1P, how do you connect 12.6VDC for the filaments. Its no issue on the 5687, but the 6n1P is only a 6.3V, correct?

The only way I saw was to connect the heater CT (Pin 8) of the 5687 to the 4 pin of the 6N1P and connect the 5 pin of the 5687 to the 5 pin of the 6N1P, correct? Manual doesn't make sense (or maybe thats' what the manual says and I didn't read it correctly)
 
#736
Aikido PSU Question

Hi, I am building a dual mono octal version of the Aikido line stage, with 6SN7 tubes wired in series. I think the heater power supply needs to be 12 V and B+ would be 300.

I will be using the Aikido PSU PCB show earlier in this thread,
Can anyone recommend a transformer that I can purchase online.

Also, can anyone recommend a recommend value for C1?

Lastly, would I connect the "heater bias" to the "H+" on the Aikido PCB? I understand that the B+ of the PSU PCB needs to be connected to the B+ on the Aikido line stage PCB, but I am not sure where the "heater bias" is to be connected on the Aikido line stage PCB.

Thank you

Kris
 
#737
For B+ of 300V. Transformer should be

Output 1 - 0-275V, 60mA
Output 2 - 6.3 - 0-6.3, 1.5 to 2A
Output 2 - 6.3V-0-6.3V, 1.5 to 2A


Solder wires from heater bias point on PCB to center tap of both 6.3V - CT - 6.3V windings

C1 could be .47 or .68 or 1 mfd/630V polyester capacitor.
 
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