Aikido Cathode Follower

[Bengali]

Hi,

has anyone built JB's aikido cathode follower?
how do you like the sound?
I like that is only uses 2 tubes but no gain.

Which would you prefer? 4 tubes with gain or 2 tubes without for a pre?

Which 6cg7 NOS tubes brands are good buy on ebay?

[DualTriode]

Originally Posted by Bengali

Hi,

has anyone built JB's aikido cathode follower?
how do you like the sound?
I like that is only uses 2 tubes but no gain.

Which would you prefer? 4 tubes with gain or 2 tubes without for a pre?

Which 6cg7 NOS tubes brands are good buy on ebay?

Hello,
I have built 3 ACF’s. Two point to point and one on the new PCB. I am pleased with the performance of the ACF.
What I like about it is this, the sound is solid, it has a boot in the face slam that was missing with the CD player connected to the power amplifier. The ACF is very clean and very quiet. Why not an Aikido you say? A gain of one is just what is needed any higher gain is burned up in the attenuator. I use it between the output of the RIAA preamplifier and a SET power amplifier. The BCF drives the interconnects and power amplifier easily. I use a ACF to drive a pair of Triode Power Tubes (no other driver) for my headphone amplifier. Again very clean and quiet.
RCA NOS
DT
All just for Fun!

[Bengali]

Hello,
I have built 3 ACF’s. Two point to point and one on the new PCB. I am pleased with the performance of the ACF.
What I like about it is this, the sound is solid, it has a boot in the face slam that was missing with the CD player connected to the power amplifier. The ACF is very clean and very quiet. Why not an Aikido you say? A gain of one is just what is needed any higher gain is burned up in the attenuator. I use it between the output of the RIAA preamplifier and a SET power amplifier. The BCF drives the interconnects and power amplifier easily. I use a ACF to drive a pair of Triode Power Tubes (no other driver) for my headphone amplifier. Again very clean and quiet.
RCA NOS
DT
All just for Fun!

Thanks DT.

I appreciate the great feedback. I will try one.

What's your preference for power supply with the BCF?

Which tubes did you decide on?

I will keep an eye out for the RCA NOS tubes.

[Sheldon]

6dj8 or equivalents are a good choice. The heaters are designed for cascode operation, so the heater to cathode voltage is not a problem. And they work well at relatively low voltages, and have fairly high transconductance for low output impedance, and good enough u to make a good follower.

Sheldon

[Joachim Gerhard]

I build this. It sounds great. Very dynamic and wideband and totally quiet.
I have shown the tubes as Fets because my editor can not draw them.
It runs on ca.7mA idle and the tubes get a bit hot. Next time i reduce to 6mA by raising the cathode resistor values.

[DualTriode]

Originally Posted by Bengali

Thanks DT.

I appreciate the great feedback. I will try one.

What's your preference for power supply with the BCF?

Which tubes did you decide on?

I will keep an eye out for the RCA NOS tubes.

Hello,
For a power supply I like to use PS-2 Solo, sometimes a point to point home brew, the one I am using with the ACF in the headphone amplifier I bought from John. The voltage is set at 250 volts. The tubes were selected from stock on hand, Sylvania 6BQ7A.
DT
All just for Fun!

[Bengali]

Hi DT,

What values should I use for C6 and C9 for BCF?

just got a nos pair of 6dj8 amperex and will try those for the BCF.
was planning to get one of JB's psu pcb's along with the BCF.

thanks.

Hi Joachim,

I will take a look at your circuit. Thx!

[Sheldon]

Are you doing a BCF or an Aikido CF? Here's what I'm using after my
phono amp. The cathode resistors are sized for about 80% of max power (2W total for both triodes).

[DualTriode]

Originally Posted by Bengali

Hi DT,

What values should I use for C6 and C9 for BCF?

just got a nos pair of 6dj8 amperex and will try those for the BCF.
was planning to get one of JB's psu pcb's along with the BCF.

thanks.

Hi Joachim,

I will take a look at your circuit. Thx!

Hello Bengali,
For both C6 and C9 I used Wima MKP 10 0.68 uf. The ACF user manual has good discussion for selecting capacitor values. John provides a formula for C6, This formula produces a minimum recommended value.
BTW In my first post I lost focus and typed BCF by mistake, all my references here are to the Aikido Cathode Follower, ACF
DT
All just for Fun!

[Bengali]

stupid of me to assume, I thought BCF is same as ACF.
what does the 'B' stand for?

I'm going to build the aikido CF since JB has new boards out.
C6 and C9 can be up to 1uF so I'm curious what you are using and why.


thanks