Ok, another Aikido thread if no one minds.
I purchased (2) power supply boards so I could put together 2 separately powered Aikido channels for the total experience.
I was lucky enough to have salvaged (2) transformers from 2 commercial 6V6 SE paging amplifiers for my power transformers.
My transformers were 275-0-275 with plenty of spunk on the high voltage side but somewhat lacking in the current department when lighting the 6.3 volt filament. That was my reasoning for using two transformers instead of one.
I tried the 6N1P for the 1st tube and the 5687 for the second tube
and found the sonic signature to be great.
My second ecperience was to try a 6FQ7 in the #1 tube spot with a 5687 in the second spot.
I am enjoying the 6FQ7 better than the 6N1P. Seems more open, free and uncluttered. This may or may not account for the higher price on ebay for this tube.
Still sitting on the counter in the garage without an enclosure at this time.
What is the status of your diy Aikdio project?
I purchased (2) power supply boards so I could put together 2 separately powered Aikido channels for the total experience.
I was lucky enough to have salvaged (2) transformers from 2 commercial 6V6 SE paging amplifiers for my power transformers.
My transformers were 275-0-275 with plenty of spunk on the high voltage side but somewhat lacking in the current department when lighting the 6.3 volt filament. That was my reasoning for using two transformers instead of one.
I tried the 6N1P for the 1st tube and the 5687 for the second tube
and found the sonic signature to be great.
My second ecperience was to try a 6FQ7 in the #1 tube spot with a 5687 in the second spot.
I am enjoying the 6FQ7 better than the 6N1P. Seems more open, free and uncluttered. This may or may not account for the higher price on ebay for this tube.
Still sitting on the counter in the garage without an enclosure at this time.
What is the status of your diy Aikdio project?
Built mine with octal 12AH7 in both positions, but biased with a 2K2 on the input and a 1K on the output (330V B+). A bit of an odd one in that I transformer coupled both input and output. Once I got the output transformer grounding sorted out, it has been a well behaved performer. Bill.
i built up an Aikido with a 6SJ7 into to a 6922. The gain is pretty high, but the noise is really low. The pentode was hand picked for low noise and microphonics. I used a pretty stiff 350V-ish mosfet-regulated chokeless supply. The sound is sweet, with some pentode roundness. I'm diggin' it.
i built up an Aikido with a 6SJ7 into to a 6922.
Could you post the schematic? I have an Aikido with 6dj8 and ecc81, but i want more gain and i would like to use a 6EJ7 i have at hand.
stalker said:
Could you post the schematic? I have an Aikido with 6dj8 and ecc81, but i want more gain and i would like to use a 6EJ7 i have at hand.
Here is the schem without the component values since you would have to tweak them for your tube anyway.
I think I ran the 6922 with either 390r 0r 470r cathode resistors (don't remember which I settled on) and a 500K trimmer as the R9, wired as a variable resistor... a 470K-ish setting produced the lowest noise. I ran the grid stopper before the grid to ground at the input to ditch a little input signal at first, but I have moved it to the other side since then. The C3 snubber is probably not neccessary, but I usually have one there to tweak the brittle high end of my crap DAC. I had a variable B+ supply, and ran it between 290v and 350v, and finally settled somewhere in the middle, but it sounded pretty good over most of that range.
Attachments
Used 6N1P, now using 6FQ7/6CG7 into 5687's without changing any operating points. Sounds good either way.
Mr. Aikido working in the dark, as usual.
The setup,
the little gold box is a 12AU7 cathode follower to drive the Crown DC150 to Subwoofer. Sony 685 modded with tube output stage, my Aikido drives 2 EL84 based monoblocks to Alk's modded Klipschorns.
dr._sleep
Mr. Aikido working in the dark, as usual.
An externally hosted image should be here but it was not working when we last tested it.
The setup,
An externally hosted image should be here but it was not working when we last tested it.
the little gold box is a 12AU7 cathode follower to drive the Crown DC150 to Subwoofer. Sony 685 modded with tube output stage, my Aikido drives 2 EL84 based monoblocks to Alk's modded Klipschorns.
dr._sleep
burnedfingers said:aletheian
Would you mind posting your B+ and resistor values? I realize values may need to change but your circuit looks very interesting.
Thanks,
Joe
I'll post what I can remember, but I tried a lot of changes, and don't remember which I likes best. I tried higher gain version, with a 220K plate resistor on the pentode, biased a bit cooler (2mA), and also a lower gain and triode strapped version with much more current (10mA). So I'll just post what I remember. ALSO, I used values of resistors for the tester circuits that I has lots of, so they are probably not exactly optimal.
Attachments
Winyl said:My Aikido are hardwired with 4 6189tubes that was waiting for somthing to do.Mostly parts i had before exept caps,around 290V B+
Very good linestage,used togehter With passiv attenuator,replaced BUF03 output.
Peter
OOO... that's a good looking amp!
burnedfingers said:aletheian
How quiet is your 6SJ7 Aikido?
Dead silent running from my system into my hard wired gainclone monoblock. I am very impressed with the the Brooksie design. It is so quiet that when I first powered it up, I thought something was wrong, but I cranked it up , ungrounded the input and touched the hot contact of the input jack with my finger... well I was greeted by a mighty "BZZZZZTTT" through the speakers that nearly gave me a heart attack.
But like I mentioned before, it has a definate Pentode character, but I had a few NOS RCA 'hand selected for first stage' 6SJ7's lying around ,and some nice 6922's, so I figured I'd just give it a try. Some 6SJ7's tend to be noisy though. I am thinking of trying a 6AU6 as well, since I have a couple of those.
burnedfingers said:aletheian
Does pin 3 of the 6SJ7 need to be grounded ?
Yes, as far as I know, the surpressor is not tied to the cathode internally. Also, Pin one is the metal , I put that to chassis ground.
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