Improving the Aikido line stage...

[Bas Horneman]

What is the ratio you used on the second resistive divider?

It should be 56% not 50%... not sure what the Mu is of the 6n6p I'm assuming 15.

Ratio = 1/mu + ½ according to tubecad.

 

[J Epstein]

It seems to me that there must be grid current flowing if there is an assymetry?

-j

 

[sparkle]

Hi to all,
Bas - we have here three dividers - i assume that You are talking about the one that has cap in series.... if so - that one doesn't decide how this line amp works in dc terms (so to say)..... i think.... someone correct if i'm wrong.... it only decide if You have distortion cancelation or not..... the other resistors are 1M in series with 1M.
And if You have read everything (i know You did) You will see that my nonsymetry is moving from one channel to the other when I move that particular tube to the other channel and if it is staying in the first stage of the line. If I put her in the second stage than the non-symetry is not that sygnificant - which is somehowm logical to me..... it is interesting ..... so, no passive component of the circuit is causing the problem but the active one....... which is strange to me.... that is why i am asking myself how this is possible.....

 

[sparkle]

It seems to me that there must be grid current flowing if there is an assymetry?

-j

Maybe You are right - will check today when back from work...... Will check on grid resistors if there is any voltage drop accros them (where i can check).......

I thought about that too but i think that everything here is pre-determined and that this can't be happening.... but it is,.....

 

[sparkle]

O.k. - i have checked everything - everything seem to be o.k.
How about this => if the two triodes in one glass envelope are not similar could this be the problem?
I have found some russian tubes not to be almost identic in one envelope. If this is the case here could this be the reason => i think that this might be my problem????!!!!
sunny

 

[Bruce Anderson]

I think you will find that the safety resistors do not control the voltage splitter duties (unless, for instance, the input tube is pulled.) It is indeed your unmatched input tube that is causing the problem. In fact, you can snip out the safety resisters and there will be no change in voltage splitting. The better matched your tube halves are the better the null. Having said that, I say hook it up and let us know how it sounds and how one channel does or does not sound different from the other. (Said the man listening happily to his 6SN7 Aikido as he types)

 

[sparkle]

I think you will find that the safety resistors do not control the voltage splitter duties (unless, for instance, the input tube is pulled.) It is indeed your unmatched input tube that is causing the problem. In fact, you can snip out the safety resisters and there will be no change in voltage splitting. The better matched your tube halves are the better the null. Having said that, I say hook it up and let us know how it sounds and how one channel does or does not sound different from the other. (Said the man listening happily to his 6SN7 Aikido as he types)

Yeah I agree - right - i have only my multimeter to determine is everything o.k. with the aikido - and i don't think that my power amplifier is going to like the aikido the way it is working now.... (solid state)...
I only had 4 of these tubes (more is coming) - although i might turn over to some other types just to see if the line is working.... will do that tomorrow or the day after..... happy listening.... sunny

 

[cerrem]

On the lighter side ....
The first improvement is to RENAME this line-stage....
AIKIDO makes it sound like a line-stage Jackie Chan would use, since it sounds like Marshall Arts

Chris

 

[heater]

No you can't change th name. From one description of Aikido, which is a Japanese martial art, we get:

"...aikido's techniques are designed to control an attacker by controlling and redirecting their energy instead of blocking it."

So, if noise in the power supply is our attacker, we don't try to block it but rather use it to cancel itself out. Which is what the Aikido amplifier does.

The name is very apt.

 

[sparkle]

today i am sad.....
i have made my aikido with 6n6p...... i turn it on yesterday..... i have had a slight non-similarity in one channel. one tube had been bad.... triodes in envelope were not similar..... i thought - o.k. i will put in first stage 6n1p - just to try.... when i turned it on ..... i have measured 3.5mA on 6n1p which is low for them .... but hey - just to try it is o.k...... i connected everything in my system.... turned the heater on and suddenly i have had humming when the tubes started to heat (not emediatelly). i said... o.k..... how can this be possible.... so my friend and i started to look arround the aikido....
long story made short.... when i put 6n1p in the line amp i have forgot to put some bleader to turn the ht voltage down.. so the voltage between kathode and heater of the 6n6p was arround 120V - and they withstand only 100V.... i belive that i broke them,......and when i remember that i have 4 pieces of 6n6p..... now ... only one is good.. two of them have brkoen Ufc and one is non-simetric......

So.... watch Your tubes....and happy diy
sunny

 

[thoriated]

Hi, Sunrise -

Sorry to hear that. However, putting only a 20% overvoltage between heater and cathode shouldn't kill a properly designed tube anywhere close to that fast. I once had a circuit with a fault (now corrected) where 100% overvoltages would take weeks to months to do the tube in. Those 6N6P's may not be too reliable at spec.

 

[sparkle]

Hi, Sunrise -

Sorry to hear that. However, putting only a 20% overvoltage between heater and cathode shouldn't kill a properly designed tube anywhere close to that fast. I once had a circuit with a fault (now corrected) where 100% overvoltages would take weeks to months to do the tube in. Those 6N6P's may not be too reliable at spec.

that seem to be only explanation ..... 6n6p seems to be within specs - too bad.... i know some tube like 6p3c-e that can be driven like hell and they would withstand it.....
my fault i say..... now i must think of something to hear how aikido works..... i'm thinkin' about 4 pieces of 6n1p in the same circuit...... i know this is not the best setup for the 6n1p (cathode resistors are 470R).... but i can't wait till that 4 6n6p come...
or maybe to combine 6n1p with e88cc???? suggestions?

 

[sparkle]

hi, guys
i have tried the same amplifier as with 6n6p (didn't work because of the tubes)... now i am sure of it - today i have also tried the same preamp with 6n1p.... it worked imediatelly...... everything is o.k. - didn't listen to it long because the preamp is not made for 6n1p but for 6n6p..... so i am sure that the cause of the problems i have had were the tubes........ i will wait for the 4 tubes i have oredered from ebay.... then i will try to listen also....
regards
sunny

 

[Bruce Anderson]

220 volt B+ with 470R cathode resisters is GOOD for 6N1P Aikido. One of JB's example operating points. This should be fun!! Assuming you are floating heater something like 40-60 volts above ground. Open a pale Ale, put your feet up and let that puppy start burning in with some Ronnie Earl jazz/blues. (bet you wind up liking the 6N1P quite a bit better than the 6N6P without special matching)

 

[sparkle]

220 volt B+ with 470R cathode resisters is GOOD for 6N1P Aikido. One of JB's example operating points. This should be fun!! Assuming you are floating heater something like 40-60 volts above ground. Open a pale Ale, put your feet up and let that puppy start burning in with some Ronnie Earl jazz/blues. (bet you wind up liking the 6N1P quite a bit better than the 6N6P without special matching)

well - this might be true but the total gain of the preamp is to high for my power amplifier - i think that gain of 10 is a little bit high but i could live with it .... gain of 17 is to high....... although 6n1p seems to be quite a runner (i have nos tubes from the 60's )

 

[dave dove]

back from holiday

i have been using 6n6p in aikido pre
built as per JB specs for 6n1p into 5687
430R cathode resistors 220V HT
with no problems at all

6n1p had arrived when i got home
so i put two in first stage
measures good and sounds better

must be your 6n6p tha problem
how's it going now?

dave dove

 

[Bas Horneman]

must be your 6n6p tha problem

Agree...I tried them in the first spot..no joy...hum (as predicted by John Broskie because of the lowish mu)

 

[dave dove]

bas

i've had no problems using 6n6p either

dave dove

 

[Bas Horneman]

Hi Dave,

Oeps...I was not clear enough..I did have problems with the 6n6p...but that was in the first position, where John Broskie predicted it would because of the low mu. In the second position they work like a charm.

Regards,
Bas

 

[sparkle]

Sorry guys for not replying - i am moving from one apartement to another - lots of work to do in new one - no time for audio
but - 6n6p were the problem - i am still waiting for 4 pieces that I have ordered from ebay (had problem there with payment - don't know why - hope this will be o.k.) if they don't come I still have 5687 (lot's of them). Before I start moving I tried 6n1p - they are good but to much gain - so maybe 5687 all through the way would be the one to go - don' know, must try but no time so this will wait a little bit.......to bad... but 6n6p was the problem......