+1
The 9 pin version opens the door a lot more for tube rolling. I am running 6CG7 inputs into 5687 outputs for my Aikido and it drives all of my amps just fine including:
SimpleSE
300BSE
Moskido
Pass F5
EL84 Push Pull
Great, thanks for the input! I will be using the tubes in an Aikido preamp using the glassware all-in-one PCB.
I do not believe I can have less gain unless I attenuate the input signal.... My Anthem Pre1 had a switchable attenuation on the input, and it clearly degraded the signal so I am going to avoid that solution.
The 6cg7 cjkpkg mentioned has the same mu as a 6sn7 so it is possible a gain of ~10, or nearly 20 dB would work fine.
I know the 9 pin has a lot more tube options but I have read about the octals sounding better, and there are a lot of reasonably priced 6sn7 tubes around. I can get NOS '60s Russian Foton 6N8S for $5 each and NOS Sylvania 6SN7GTB for about $20-25 each in matched pairs.
I had the same pre1, but it is sold to pcx for $275. Pcx did send me the schematic so I could have attempted a repair, but this isn't the 1st problem I had with the preamp in the 5 years I owned it, and it is nearing 20 years old. It is not an extremely simple circuit and I did not look forward to diagnosing further issues it might have had. My pre1 did have 2 internal switches that reduce gain for the linestage, I think this was added later as the normal 28 dB gain is excessive for many applications. I even built my Simple SE to have much less gain using a 12bh7 driver tube vs the 12at7 normally used for building it as an integrated amp, but even so the volume control on the pre was usually around 9-10 o'clock, 11-12 o'clock was around max volume on my 93 dB efficient single driver Omega speakers.
It was a $1500 preamp in the mid '90s, and even then it was considered a good value for the money so I know it's not going to be easy to match it...
I don't know who or what Aikido is!
Gain may be reduced by reducing the value of the anode load - assuming that the amplifier is resistance-coupled. Otherwise it's tricky.
Yes 6CG7 is claimed to be identical electrically to 6SN7. I have no view on "sound" from particular types. What I will say is that 6SN7 and its cousins (7N7, 12SN7 etc.) do produce very little distortion. I have measured this myself.
Whether this accounts for their reported "sound" I couldn't say. I'm afraid I am suspicious about claims for the "sound" of components. I once recall an on-line argument about "the sound of solder" !!!
I abandoned religion very many years ago and do not intend to return to mumbo-jumbo of any sort.In Valve Amplifiers (3rd Edition) Morgan Jones covers all this pretty thoroughly with vast quantities of measurements. He shows that 6SN7 is the best for distortion, ECC82/12AU7 the worst. In fact none of the nine-pin types he tested were as good as the 6SN7/12SN7/7N7.
Aikido, what is it?
This has evolved into many iterations by now with PSU integrated "all in one" versions in both noval and octal as well as other ready to stuff PCB's like regulated power supplies and phono preamps.
Some have classified the Aikido family as "giant killers" and Broksie also includes these all in kit form which is a REALLY good deal and he supplies quality parts.
It is an intersting topology and while I can only compare to other amps I have built, i can say that the Aikido's I have built sound fabulous. I do not have any $2000+ gear that I own that I can compare to.
Thanks for the link.
Yes an interesting idea, though I suspect should I ever build anything myself again, then I would prefer to stay with my differential pairs, which when properly executed do provide good PSRR. Also with the new "MAIDA" regulator discussed elsewhere in this forum perhaps power supply noise (6uV on a 400V supply) might no longer be a problem?
With the elevated voltages on the cathodes of the upper valves I would be very careful to ensure that my second stage valve sat on an elevated heater supply. This of course would necessitate using identical valves for each stage.
No doubt this has all been discussed at great length in the past, but note my earlier comments on 6BX7. One could I suppose float the heater supply on say +60V and hope for the best...
Heater voltages are raised 1/4 of B+ in the Aikido.
This is the pcb I am about to order... probably right now.
Aikido Octal All-in-One Kit
I know about noisy tubes, but not that there would be a power supply problem
I was speaking in general terms of course...
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