I got Aikido Octal all in one which he discontinued. So you need a separate PS.
1. Go with his default listing. However, most of his manuals are missing some parts and wrong values.
2. Best to ask people in here for those missing parts unless you get answer from John.
3. Putting all together is easy as long as you get all the parts.
4. Stay with aluminum chassis otherwise, you would get hum with steel. I feel like doing the chassis take longer and harder than solder the parts on PCB.
https://www.diyaudio.com/community/...o-all-in-one-octal-acf-2-buffer.330985/page-5
1. Go with his default listing. However, most of his manuals are missing some parts and wrong values.
2. Best to ask people in here for those missing parts unless you get answer from John.
3. Putting all together is easy as long as you get all the parts.
4. Stay with aluminum chassis otherwise, you would get hum with steel. I feel like doing the chassis take longer and harder than solder the parts on PCB.
https://www.diyaudio.com/community/...o-all-in-one-octal-acf-2-buffer.330985/page-5
I use a Neurochrome Maida regulator in my Aikido:
https://neurochrome.com/products/21st-century-maida-regulator
Not cheap, but it makes for the simplest possible power supply. I have a 6X5 rectifier, 20uF, Neurochrome board and 10uF. That's it. Dead quiet. Chassis is enough heat sink for this circuit. Advantages are that it's adjustable so you can experiment with various operating points. And it sounds terrific. You can also recycle it for other projects down the road. By the time you buy a bunch of chokes, you've almost paid for the Neurochrome. Add a simple DC supply for the tubes and you're done.
There's also a fellow here who designed mono PCBs for the octal Aikido, maybe someone has the link, I can't find it at the moment. You can send the free files to JLCPCB and have the boards in a few days.
https://neurochrome.com/products/21st-century-maida-regulator
Not cheap, but it makes for the simplest possible power supply. I have a 6X5 rectifier, 20uF, Neurochrome board and 10uF. That's it. Dead quiet. Chassis is enough heat sink for this circuit. Advantages are that it's adjustable so you can experiment with various operating points. And it sounds terrific. You can also recycle it for other projects down the road. By the time you buy a bunch of chokes, you've almost paid for the Neurochrome. Add a simple DC supply for the tubes and you're done.
There's also a fellow here who designed mono PCBs for the octal Aikido, maybe someone has the link, I can't find it at the moment. You can send the free files to JLCPCB and have the boards in a few days.
I have built the Octal Aikido using 6SN7s. Sounds wonderful. Strongly recommend the New reissue Tungsol 6sn7. You can definitely hear the difference in tubes with this pre. One caution though I ordered and built the three switch volume control with my Pre and you hear a pop as you switch to different volume settings. Don't know if it is just mine or not. have tried to troubleshoot but no luck. No DC offset at the volume control so not sure what is causing.
I have a 6SN7 octal version. Just because a DAC has a possible output voltage of 2v doesn’t mean you don’t need some gain. Depends on the level of the mix and the sensitivity of the amp. I put the gain reducing divider into mine but sometimes I wish I had a bit more gain. Have plans to make it switchable. Otherwise it sounds beautiful and several friends wish they had one.
I ordered some of the octal boards mentioned above. Haven’t built with them yet but they look like winners.
I ordered some of the octal boards mentioned above. Haven’t built with them yet but they look like winners.
Here is the blog (dated 14 August 2020) which contains that particular article. It is buried pretty deep in this blog...it's about 3/4 down the page.
https://tubecad.com/2020/08/blog0510.htm
That was me unless there are other designs around.
That board is still untested. I have built the aikido boards but not a psu to power them yet.
Baby came along before I completed that build and I've been wrapped up in other builds in the last year or so.
I promise I will get to it soon. Otherwise somebody else is welcome to verify the design
https://www.diyaudio.com/community/threads/home-brewed-aikido-preamp.354383/
Bottom of the first page.
It does appear as though one person may have used them but there was no feedback. Could be they worked great and that was that. Could be their still sitting in a box...
There is also tubes4hifi.com They are not cheap but they do supply a full kit. This was my entrance into the aikido world which got me hooked.
Currently I am using a Broskie 12vac aikido set up for 18v operation with 12au7s. Great preamp and quite simple to get going. Not as good as a 'proper' aikido with a nice power supply and some 6sn7s. But probably 90% of the way there.
I was happy enough with the 12vac aikido to spend half a year building a nice chassis for it to live in rather than an open test rig.
Last edited:
In my case, this is how it was done with the NFB. The amplification is now about 2.5x (8dB) and it was 18x (25dB) with 5670/6CC42 tubes. Checked with an oscilloscope and everything is stable, no oscillation. The sound is better than without NFB, cleaner and faster, with more details. The frequency range is wider, before it was around 200kHz -3db, now it is around 500kHz -3db. And the output impedance is probably lower, I just didn't measure it. Only the input impedance is lower now, around 35k, that is inevitable.
Attachments
That one person was me, and yes, they're still sitting in a box. ;-) I'm planning to build one for a friend but haven't gotten around to it yet.
This is all very interesting, a bit above my audio electrical level, but I will get there! What is exactly the motorboating issue with the Aikido power supply? would that also happen with the PS-21 power supply that John sells?
I am leaning towards the Octal version, even if my skills would perform better with the 12v version. Projects take time so I would prefer to go at once for the Octal. Surely, I will find myself lost along the way, but I have been there before and hopefully I count with the help from you all!
Thanks for the suggestion, I think it will pay for itself pretty fast once you start experimenting with operating points. That I understand easily.
On the other hand, and this is where I am lost, if I use this Maida regulator in the power supply for a Octal Aikido, what else would I need to buy to complete the power supply? surely I will not need the PS-21 PSU that Broskie sells, but what else would I need?
Thanks,
Alan
This is also interesting for me, thanks for sharing. Could you elaborate more on the sound of the Octal Aikido? I have listened to several preamps, some Conrad Johnson, Sonic Frontiers, a custom DHT 26, and others. The one I like the most was the DHT 26, somehow it had a 3D nature to the sound that the others did not have, they all had a bit of that tube sound but they did not came close to the DHT.
The only other thing you need is a 6.3 volt filament supply. Some people use AC for the filaments. I think this is flirting with noise issues and that a DC supply avoids any issues. Once again, Neorochrome to the rescue, but also, again at a hefty price:
https://neurochrome.com/products/universal-filament-regulator
Much cheaper and simpler is a 7 volt transformer, a bridge rectifier, cap, dropping resistor and cap.
By the way, I use Antek toroidal transformers for my Aikido.
@inkasound
My point about the octals was that I have owned other tube preamps that were all novals 12ax7, 12au7, 6dj8. I definitely think the sound through the 6sn7 is a little more coherent and cleaner sounding. Now the biggest difference I heard was using some used mixed brand 6sn7 vs brand new TungSol 6sn7s The new ones sound much better and the older ones all test as new so not like they were bad.
My point about the octals was that I have owned other tube preamps that were all novals 12ax7, 12au7, 6dj8. I definitely think the sound through the 6sn7 is a little more coherent and cleaner sounding. Now the biggest difference I heard was using some used mixed brand 6sn7 vs brand new TungSol 6sn7s The new ones sound much better and the older ones all test as new so not like they were bad.
It wasnt an "Aikido power supply". Just my own design with a 5U4G tube rectifier, 100uF motor run caps and big 15H chokes. Some the the B+ ripple, even as tiny as it was, leaked thru into the preamp signal stage and caused a constant 5Hz oscillation of the woofer. It couleld be blocked with a smaller coupling cap, but that would also roll off the bass a bit. I was planning to use a more activity regulated/stabilized PSU when I rebuilt it.
