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Old 25th November 2012, 09:00 PM   #551
Stef is offline Stef  United Kingdom
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Default 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?
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Old 30th December 2012, 07:36 PM   #552
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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!

Last edited by ClefChef; 30th December 2012 at 07:38 PM.
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Old 10th February 2013, 10:36 PM   #553
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Just to keep this thread alive. How many of you Float the ground of your aikido pcb and how many actually use the J7 To ground it to chassis? Would grounding it the the 3rd prong be any different?
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Old 22nd August 2013, 06:31 PM   #554
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Can anyone tell me where to buy high quality Toggle switces for audio use?? Right Now, i use two RS Toggle switches, One for the main power and one for the heaters. The toggle switch for the main power slowly went out and Man, Did I get hum!!

Click the image to open in full size.

Last edited by migkiller1971; 22nd August 2013 at 06:33 PM.
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Old 2nd February 2014, 12:40 AM   #555
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Keeping it alive!! Has anyone used a choke in a octal all in one LSA?
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Old 28th May 2014, 12:55 AM   #556
Yaho is offline Yaho  United States
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Default 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
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Old 28th May 2014, 03:58 AM   #557
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i have built both, the differences are subtle so that i tend to favor CCDA for its simplicity and lower cost....YMMV
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Old 28th May 2014, 03:59 AM   #558
AJT is offline AJT  Philippines
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Quote:
Originally Posted by migkiller1971 View Post
Keeping it alive!! Has anyone used a choke in a octal all in one LSA?
a filter choke is a must in all my tube builds...
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Old 28th May 2014, 04:41 AM   #559
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Quote:
Originally Posted by migkiller1971 View Post
Just to keep this thread alive. How many of you Float the ground of your aikido pcb and how many actually use the J7 To ground it to chassis? Would grounding it the the 3rd prong be any different?
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.....
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Old 28th May 2014, 05:34 AM   #560
Yaho is offline Yaho  United States
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Quote:
i have built both, the differences are subtle so that i tend to favor CCDA for its simplicity and lower cost..
That's all i needed to hear. I will go with the ccda then. thanks

one more question please. does the diode have to be 14007? Or can i use any diode?

Thanks again,
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