[ClefChef]

Wonderful Aikido tube preamplifier, based on John Broskie Aikido schematic. The tube compliment is 6N1P-EV and 6N6P pairs that are ideal for low noise and low output impedance operation. Preamp has two pairs of inputs and a pair of outputs.

Technical details: Custom power transformer - dual 115V primary (could be rewired for 240V mains), 250V and 8V secondaries. Regulated B+ 220V CCS, heaters - regulated 6.3V DC. NOS carbon comp grid stopper resistors, Kiwame cathode resistors. Output coupling caps MKT1813 6.8uF, noise canceling caps - Solen, noise canceling resistors - precision Dale. Signal wiring - silver teflon.

Aikido is certainly one of the best tube preamplifier I have heard in terms of noise level and musicality. The sound could be described as open and effortless, with incredible detail and resolution. I am burning it in with Tekton OB4.5, driven by modified WPA 3.5 monoblocks, and those 4" Fostex drivers let me hear the details I've been missing with other preamps.

SOLD

[ClefChef]

bump and price drop.

[ClefChef]

bump

[raindance]

Nice looking unit. What is the gain with your tube complement? Is there any hum?

[ClefChef]

Absolutely no hum - dead silent. The gain is a tad larger than my JC-2 preamp, don't know exact number, should be on par with your garden variety linestages.

[ClefChef]

SOLD.

[4krow]

I would just like to comment that this pre-amp looks really great. No wonder it sold so quickly.
  Greg

[ClefChef]

I plan on building another one, this time with AC filaments. Will post the pictures when ready.

[4krow]

Yah, these designs are pretty robust.    What is the benefit of an AC filament supply?

[ClefChef]

AC filament supply will offer lighter load on power transformer. 6n1p and 6n6p tubes draw 740ma each, totaling 2.5A @ 6.3V which is asking a lot from regulator and transformer if using DC. Second biggest problem is the absence of suitable power transformers as most transformer manufacturers are still stuck with 6.3V and 12.6V secondaries, we need at least 1.5V higher than that for regulation.

[4krow]

Thank you, that now makes sense to me. It will also help me with future endeavors. There apparently is much that I need to learn about tube circuits. Broskie doesn't offer much in the way of help from his site, so I rely on a little help now and then to make things go smoother. Anyway, I am interested in seeing your next project. I also have one on deck, but it might a week or so before it's ready.

                        Regards,   Greg

[ClefChef]

I tried many configurations of Aikido preamps and I think I arrived at one that sounds the best...
This Aikido sounds miles better that any other tube preamp, including the ones I owned or own or my friends own, and those are the names of Conrad Johson, Wright Sound Company, Bottlehead, etc.

[4krow]

Looks like it has 2 inputs, and 1 output. Also, I see a choke in the power supply. I like the chassis, but I think that I will be using 2 wooden enclosures for my next attempt. Really wish that I would have discovered all of this 20 years ago. I am 56 now, and hearing is slightly less than before.
  Have you ttried Herbies tube dampers? They seem to be gpood quality for a modest price. Also, the stepped attenuators that Broskie has are incredible. I have used them in several designs, and continue to recommend them. When I arrive back home, I will send  most recent photos. Thanks for the reply...Greg