The only preamp's I have are 3 different PAS-3's, one original, one modded with the Tubes 4- HI FI boards, and another modded with the PAS-K boards, I also have a Eico-HF 85 fully rebuilt... I think of these the Eico is the winner, The PAS-K is also good, fast, high gain and dynamic but I find it a bit fatiguing after a few hours.... I'm thinking the Aikido will top them all though I haven't had time to assess yet but so far YES!
The Valves:
12DW7 Mullard
5Y3 Amperex
6F8G Emersons (nib said to be rebranded Tung Sols) with socket adapters
6SN7 National Union black glass
The 6F8Gs are really microphonic but sound terrific, I'm going to do a bit of tube rolling over the next few days as the unit burns in..
also in the photo are my Heathkit W-5M mono blocks and not seen is a "Phono Clone" phono preamp.
Cheers,
Kirk
Very good. The phonoclone is a winner too.
Are the 6F8G heaters and 6SN7 heaters in series? If so you'd want to check that they both take the same current otherwise one will be starved of heater current. If you go back and measure voltage at the heaters of each valve make sure you have ~6.3V pin 7&8 of each.
Nice gear! I've found the 6SN7 aikido has a real ballsy sound, great for rock. Thats with a valve rectifier. I might just go back and do a HV shunt supply for it and see does it make much difference.
Fran
Are the 6F8G heaters and 6SN7 heaters in series? If so you'd want to check that they both take the same current otherwise one will be starved of heater current. If you go back and measure voltage at the heaters of each valve make sure you have ~6.3V pin 7&8 of each.
Nice gear! I've found the 6SN7 aikido has a real ballsy sound, great for rock. Thats with a valve rectifier. I might just go back and do a HV shunt supply for it and see does it make much difference.
Fran
Thanks for the heads up on the heaters!, I'd forgotten about that, and I wrote to JB about it but got no reply. (he's a busy guy) as my original plan was to run a quad of them but my contact here in the states for adapters was having medical issues, so I'm waiting for another pair of those....I only ran the 6F8G's for 20 minutes or so so I don't think it created any issues and now have switched to trying out quads of 6SN7's..again thanks...ball out is right! just got through a side of LZ II RL....wild!
Cheers,
Kirk
Cheers,
Kirk
Hi,
Rolled them back in and got these readings on the dmm:
V-2 (6F8G) 6.11 vdc
V1 6SN7 6.20 vdc
V-2 ( 6F8G) 6.21vdc
V-1 6SN7 6.12vdc
I was getting 12.27vdc across H+ H-
I'm thinking this is OK.
The best combo I've found are Ken Rads in the V-1 and the Emerson 6F8G's in the V-2
Cheers
Kirk
What type of adapter did you use for the 80 since its 4 pin? Those emission labs tubes look very well built but expensive.
8 Pin Bottom To Four (4) Pin Top Tube Adapter For Rectifiers
I don't see a need for emission lab tubes. The NOS GE 5U4's sound very good as do the Russian tubes
I don't see a need for emission lab tubes. The NOS GE 5U4's sound very good as do the Russian tubes
Attachments
R15 Calculation
Hi All,
I have now built 2 akido pre-amp.
The first is a tube rectified CLCRC version and the second used John B's PS1 s/s regulated p/s - both use 6N1P's for input duty and 6N6P's for the output.
I have a slight problem and I am confused: Until recently I thought that the version using the PS1 was better (by a long chalk). But a side conversation led me to check the values I had used for r15 in that version.
In the tube rectified version I had R15 set to 79.3k (I assumed the 6n6p is much the same as a 5687).
In the PS1 version I used nearer to 87k for r15. (i.e. I had ommitted to check or set up the values properly) - yet when I changed the values back to 79.3k the preamp not only sounded very close to the tube version but also sounded worse than before????????
My questions are:
1 - is R15 all that critical for sound quality?
2 - what is the mu for an 6N6p running at about 270v using a rK of 280ohms?
3 - how sharp is the noise cancelling null point? Is it within 300, 200, 100, 10 or even to the nearest ohm????
I tried to hook up an oscilloscope to my Aikdo with a 'deliberately' noisy p/s to find this null point - I just do not seem to be able to encounter it by adjusting a trim pot.
Any takers?
Hi All,
I have now built 2 akido pre-amp.
The first is a tube rectified CLCRC version and the second used John B's PS1 s/s regulated p/s - both use 6N1P's for input duty and 6N6P's for the output.
I have a slight problem and I am confused: Until recently I thought that the version using the PS1 was better (by a long chalk). But a side conversation led me to check the values I had used for r15 in that version.
In the tube rectified version I had R15 set to 79.3k (I assumed the 6n6p is much the same as a 5687).
In the PS1 version I used nearer to 87k for r15. (i.e. I had ommitted to check or set up the values properly) - yet when I changed the values back to 79.3k the preamp not only sounded very close to the tube version but also sounded worse than before????????
My questions are:
1 - is R15 all that critical for sound quality?
2 - what is the mu for an 6N6p running at about 270v using a rK of 280ohms?
3 - how sharp is the noise cancelling null point? Is it within 300, 200, 100, 10 or even to the nearest ohm????
I tried to hook up an oscilloscope to my Aikdo with a 'deliberately' noisy p/s to find this null point - I just do not seem to be able to encounter it by adjusting a trim pot.
Any takers?
I am building Broskie's all in one Aikido preamp with LV/HV PS-1 style supply, and I plan on using 6n1p+6n6p tubes.
Questions about heater supply.
Total draw for 4 tubes would be ~2.8A (650ma x 2 for 6n1p + 750ma x 2 for 6n6p) of 6.3V. LT1085 can handle up to 3A with 1.5V drop out at maximum current (should I put 1084?).
The transformer I have is 250v + 7.5v @1.5A + 7.5v @ 1.5A. I could parallel 7.5v secondaries to get 3A - would that be enough to power the filaments? I will be using full wave rectifier.
Thanks!
Questions about heater supply.
Total draw for 4 tubes would be ~2.8A (650ma x 2 for 6n1p + 750ma x 2 for 6n6p) of 6.3V. LT1085 can handle up to 3A with 1.5V drop out at maximum current (should I put 1084?).
The transformer I have is 250v + 7.5v @1.5A + 7.5v @ 1.5A. I could parallel 7.5v secondaries to get 3A - would that be enough to power the filaments? I will be using full wave rectifier.
Thanks!
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which aikido sounds better?
Hello I am about to build Aikido linestage and tetra san phonostage.
I am most likely go with board rather than doing it point to point. It seems easy that way.
Since i have a lot of sn7s laying around, I am going to build octal versions.
My question is which one? I noticed that there is CCDA Octal stereo version that employs 2 octals vs Octal Stereo that employees 4 octals. Which one sounds better is my ultimate question.
thanks
Hello I am about to build Aikido linestage and tetra san phonostage.
I am most likely go with board rather than doing it point to point. It seems easy that way.
Since i have a lot of sn7s laying around, I am going to build octal versions. My question is which one? I noticed that there is CCDA Octal stereo version that employs 2 octals vs Octal Stereo that employees 4 octals. Which one sounds better is my ultimate question.
thanks
I used an 0.1uf capacitor...not sure how that would compare with grounding the 3rd prong, but certainly there was no noticeable difference when I did solder the capacitor.....