Tube power supply for Aikido Preamp

[Tix88]

1. to use tightly matched tube sections for only the input tube. Preferably a High quality NOS tube.

-This already done

2. replace the resistor with a transistor , in the first stage, bias with LED first stage? can't remember well.

Could you explain me better?

3. Adjust the resistor with potentiometers to reduce distortion to minimum.

-Could you explain me better?

4. Make sure you use quality 1M resistors for the power supply things, 4x I think.

-This already done

 

[gabdx]

2. B-Follower, see Morgan Jones book for explanation.

3. Place a potentiometer to adjust the first tube cathode resistor to minimize THD, you need a high definition THD test bench for that.

I don't have much time tonight, I can post a picture tomorrow hopefully.

 

[Tix88]

Ok thanks [emoji6]

 

[Tix88]

2. B-Follower, see Morgan Jones book for explanation.

3. Place a potentiometer to adjust the first tube cathode resistor to minimize THD, you need a high definition THD test bench for that.

I don't have much time tonight, I can post a picture tomorrow hopefully.

Is your aikido stabilized?

 

[gabdx]

stabilized? ?

I built it like 10 years ago !!! still going strong, not used much.

 

[jameshillj]

I used an Alax Cavalli power supply from his Bijou head amplifier and it's done a marvellous job of driving my Aikido over the years - I think the pcbs are still available.

I added a series CMx to the high voltage filter caps (after the valve rec) and 'played around' with the regulated heater supply but it's essentially still the same circuit - the mods added a little more 'air' to the sound and I like that ....

 

[gabdx]

Tix , here is a link to the Aikido with different tubes and distortions

I think the 6dj8 NOS of the best quality will give you a super excellent sound in B-Follower configuration..

The 1M résistors are SUPER important in the circuit of the Aikido and not shown in most schematics, their role is to introduce feedback in the power supply. !!!!


Survey: Aikido distortion

 

[Tix88]

Here is the straightening part that I would like to achieve, how do you think? it's good? Do the caps have to be bigger? This is the scheme, which will be connected to the other filtering part already present in aikido according to the second scheme.
Thanks

 

[gabdx]

résistors very high value, caps too big

 

[gabdx]

you need to know which tubes you're going to place in, current demand.

40 mA going to 1000 R is a 40V waste and high impedance power supply

 

[Tix88]

The current will be 15ma per channel, the tubes used will be 6cg7 and 6dj8, with 200v B + as recommended by Broskie.

 

[gabdx]

do you use 6cg7 for the cathode follower? 6dj8 gain stage?

 

[Tix88]

Yes

 

[Tix88]

What values ​​of the caps are they high? Those from 1000uf? Could I make 25uf > 50uf and 100uf per channel?

 

[gabdx]

you can get same performance with C1 100uf input cap, 100R, 500uf, then 100R and 500uf for each channel.

total cap of your design is 2075uf and resistance total of 470 + 470 + 470

You can get same result with 1100uf and resistance total of 100 + 100 + 100.

 

[Tix88]

Which resistors do you recommend me to use?

 

[gabdx]

its too much into details isn't? To me it doesn't matter.

I don't like fried resistors, I use mostly fire proof resistors, they sound to me better than the PRP and caddock.

I like to use Mills non-inductive in power supplies but 5$ each vs 0.1$ for flame proof.

Unless the voltages are over 500V any normal 0.5 watts are able to do the job for the 200V 30 mA supply. Maybe double the first one to 1 watt.

 

[gabdx]

Carbon/Germanium/Silicon all have resistivity decrease with heat augmentation. Not very much for Carbon, but you can take advantage of it maybe. Metal film resistor resistivity increases with heat. Just interesting facts hehe.

 

[Tix88]

Ok thanks so much

 

[Tix88]

1M resistors must be of high quality or only extremely precise? Carbon film resistors are fine? Or rather those with metal wire?