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gurevise 1st April 2006 09:04 PM

Aikido sound?
I see lots of activity here about building Aikido 9pin and octal versions. I don't see anything about results people get.
Can you guys talk about sound from octal's and 9pin Aikido?

Dayton, OH

lndm 2nd April 2006 08:28 AM

I have built both. I think that the Aikido has such a quality that the choice of 9 pin or octal is less than many other types of amplifier. They both sound like an Aikido.

In my opinion, the Aikido sounds quite accurate, and is relaxed about the fact.

I have used it as a driver stage. The thing with Aikido is that the distortion spectra is fairly balanced even under load. It is as if it takes all the pressure and converts it to listenable distortion. So, as a driver, I could push to class A2 at the output and the driver would produce obvious distortion, but I could play 6 odd dB higher and tolerate it :cool:

Sparky OR 31st October 2006 04:11 PM

Aikido sound?
...driving what? I was thinking of using a 12AU7 variant, since I have so many of them, driving a 6V6 SE that I use either triode or Pentode connected.

jayme 31st October 2006 05:45 PM

My aikido linestage is all 6SN7. After working out the bugs (the circuit is VERY sensitive to proper grounding) and fiddling with my PSU parameters, I finally got it all working perfectly.

No hum. No hiss. No extraneous noise, period. Even with AC heaters. If I get within 1ft of my speakers, I can hear a very faint tube rush. That's it.

The sound is extremely open, airy, and clean. Like all of the "grunge" disappeared.

When my wife and I sat down to listen, compared to my old preamp (a Transcendent Sound Grounded Grid...which frankly sounded better than many commercial preamps I tried and owned), our first impression was that the difference was Surprising. Honestly, we weren't expecting to hear an instant difference....let alone be amazed by how much more clear it was. And

And the bass response was outstanding (I used AuriCap .47uF caps into a 100k input impedience on my amp).

Overall, I would say that this is *not* a warm-sounding design. However, it really allows my tube amplifier to present a natural soundstage which, to my ears at least, is tonally accurate.

Gain on my version is a bit high (gain of 10...which equals 20dB). This was too much with a normal Alpha pot, and I had to solder 100k resistors before the inputs to get a workable volume range. I suggest a stepped attenuator starting around -70dB reduction (the one from Transcendent is -68dB...I'll be dropping that in shortly.

Now that is is up and running...I've been thinking about a 2a3 push-pull class-A amplifier using 6SN7 drivers in aikido mode. And an aikdio-based phono preamp.

And, I've started to wonder what an aikido linestage using DHTs (the 26 comes to mind) would sound like...

billr 31st October 2006 06:04 PM

could you explain what you mean when you say that the Aikido is very sensitive to earthing?

what is your experience in this regard?

what did you do that caused you to say that?

I am just interested

look forward to hearing from you.

lndm 31st October 2006 11:16 PM

Re: Aikido sound?

Originally posted by Sparky OR
...driving what? I was thinking of using a 12AU7 variant, since I have so many of them, driving a 6V6 SE that I use either triode or Pentode connected.
I think I was driving 6550s (or similar) at the time. My speakers were, then, a little inefficient and I would find myself pushing the amp.

With a standard common cathode driver stage, it is the first to buckle under the pressure and produce tons of 2nd HD. A good way to go unless you push it too far and get that sound of loose cardboard slapping, like you might get by pushing some old stock car speakers past their excursion limits :D

The Aikido was a pleasant change for my ears. Eventually though, I re-designed my speakers like I should have done in the first place.

Wavebourn 1st November 2006 12:44 AM

Aikido is a "semi push-pull" amp. If tubes on top and bottom are identical and voltages on them are equal dependence of transfer characteristics on anode voltage looks like self-compensated. You may do such trick with any triode, no matter is it small finger-type or has a solid octal base.

2wo 1st November 2006 04:29 AM

A little off topic But I built a P-P amp using an Aikido front end. I used 6A5’s rather than 2A3’s

6sl7 to 6sn7 to a MQ EXO-173 for phase splitting.

Still in the tweaking stage but a very promising.
I will try to put up a corrected schematic. Soon…John

zacster 2nd November 2006 08:10 PM

We have to have a get together so we can compare aikido/amp combinations. I finished my Aikdo with 6GM8 tubes and it is dead quiet. I had no problems with the grounding, but I'm using 24v DC throughout fed by a separate pre-built power supply, no separate filament supply, no AC in the chassis at all. I'd expect it to be quiet. I could swap the PS and use battery but I haven't tried that yet since I don't think I need to.

One thing I like about the 6GM8 tubes is that they don't get too hot to touch. Plus, not having to worry too much about the 24v when testing, which ultimately I didn't need to do, it just worked.

2wo 3rd November 2006 05:16 AM

Hi Zac, I am looking forward to a meet, Marker was making noises a wile ago, Or if the crew wants to come Philly way …
The 24v Aikido is just too cool. I have to try it.

I am attaching the latest version of the 6A5. As you know it was inspired by listening to your amp. I started by dragging out the carcass of my long suffering ST-70 and lashing in a 12AU7 based driver board. Then I couldn’t and still can’t find my stash of 12AU7’s. then fate stepped in and I landed the EXO-173’s. That and a big honking power transformer, I decided to start from scratch.
I brought it down to the DC Bottlehead meeting and it seemed to be well received. A few things though. I need to raise the current in the 12sn7’s. I used what resistors that were on hand. Plus I think I could get a bit more out of it if I raised the current of the outputs till they begged for mercy. I just can’t do it to such a nice set of WWII tubes…John

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