Mas Penk said:
Hm - I see YOur point - it is a problem to calculate this..... because if You calculate the current according to ohm's law You get 2.7mA (430R/1.2V). But according to datasheets this wouldn't happen. When we look at the plate curves we see that for 110V on a plate and 1.2V on a cathode we would have around 8-10mA. And Rk would be 120-150R. The thruth is probably in between so I would say that You have 5-6mA in srpp.
When You want to calculate the current through that stage You determine what current do You want and at what plate voltage. If we assume that we want to run 5mA through 6n1p and have 110V on a plate - according to the datasheets (plate curves) we would need 2V on a cathode resistor. This gives 2V/5mA=400R. So, this is about right when You look at the sch that You have posted (400R is near 430R). So I wouldn't say that 1.2V is not right but (who am I to argue with mr. Broskie) but I think that You would have probably around 2V where he says that You have 1.2V.
The calculation is the same for the 5687 circuit - only this circuit is not srpp and You don't have gain (well You have but
)hope this helps - and please correct if I made mistakes somewhere
happy diy
best regards
dmcgown
i'm not really in a position
to give you technical answers
but
could you clarify for me
where you have put
300K resistors....
which are now 1M
the impression i get
is that they are
after cathode follower
which should be 100K
in the original circuit
why have you increased them?
i've used a lot of valves
including ecc99 for CF
with absolutely no buzz
hum snap crackle or pop
would suggest it is coming from elsewhere......
dave dove
i'm not really in a position
to give you technical answers
but
could you clarify for me
where you have put
300K resistors....
which are now 1M
the impression i get
is that they are
after cathode follower
which should be 100K
in the original circuit
why have you increased them?
i've used a lot of valves
including ecc99 for CF
with absolutely no buzz
hum snap crackle or pop
would suggest it is coming from elsewhere......
dave dove
Mas Penk said:
12b4 is a nice tube - my current preamp is running on it..... if You don't push her to hard it will sound very nice and clean (under 10mA and 80-100V plate voltage).... i take that 470R of cathode resistor and 100-110V will do the job......
i have a solid state power amp and I hope that You know that aikido will have half of the total gain of the used tube in first stage - so if You use 12b4 in first stage I think that this would be not enough..... maybe some tube with gain between 15-20 would be better- that means that You would have 7.5-10 total gain.... what do You think
off course the second stage would be great with 12b4.... have a nice day and
Actually at first i want to build all aikido from 6SN7 (based on circuit that Mr. Broskie wanted to build, i forget the blogg's series) but since i see this thread i changed mymy mind to to try this 12B4....
So... 110V and 470R on cathode.... means i have to provide 220 on B+
but can i have you suggestion the best partner for these 12B4 since i have only 12AU7, 12AT7 and 6SN7 types of tubes...
regards
So... 110V and 470R on cathode.... means i have to provide 220 on B+
but can i have you suggestion the best partner for these 12B4 since i have only 12AU7, 12AT7 and 6SN7 types of tubes...
regards
Replying to Dave Dove's question on 300K to 1M resistor:
The 300K resistor is the safety divider that is shown in "safe" version of the Aikido circuit. These have been shown, in different schmatics, as 100K to 1M resistors. I when I converted my basic version of the Aikido circuit, with only the AC divider feeding the grid of the lower tube, to the "safe" version, adding the additional divider tied to the plate of the bottom tube, is when I noticed the buzz occuring.
The 300K resistor is the safety divider that is shown in "safe" version of the Aikido circuit. These have been shown, in different schmatics, as 100K to 1M resistors. I when I converted my basic version of the Aikido circuit, with only the AC divider feeding the grid of the lower tube, to the "safe" version, adding the additional divider tied to the plate of the bottom tube, is when I noticed the buzz occuring.
Mas Penk said:
YES....
It depends what You want - I have transistor power amplifier and if I am in Your place I would go to 12AU7 (mu=18-20) or 6sn7 (mu=20-21). In both cases You would have total gain of the aikido around 10. 12au7 is similar to 6072 so You can use it also...... They are good tubes... Also I wouldn't go for 12b4 since total gain of 3 or for wouldn't be enough for my taste.... of course someone might argue about that - since we have a number of passive preamplifiers arround. I have tried 12b4 in a common cathode setup and I would like a little bit more gain for my power amp.
12at7 has mu arround 60-70 and the current is a little low so I wouldn't go for it - but if You have some tube amp that need a gain arround 30-35 You might think about it .... I wouldn't go for it..... hope his helps.....
I heard that 12AT7 is a fantastic tube to be used as a cathode follower though I have not much experience with tubes at all and have only built a plain 12B4A line stage (it is very good). Would the 12AT7 be suitable for the second stage in the aikido? It is a tube that is in current production and is readily available.
Regards,
Bill
Regards,
Bill
hifinut
have used 12at7/cv4024
but not the greatest here
dmcgown
you have said the buzz
was barely noticeable before
and that adding safety Rs
has led to an increase
i don't have an full answer
except that there must be
something there to be increased
by the addition of safety Rs
i too built without them
but put them in on JB's advice
without any sonic detriment
something else is giving them the buzzzz...
dave dove
have used 12at7/cv4024
but not the greatest here
dmcgown
you have said the buzz
was barely noticeable before
and that adding safety Rs
has led to an increase
i don't have an full answer
except that there must be
something there to be increased
by the addition of safety Rs
i too built without them
but put them in on JB's advice
without any sonic detriment
something else is giving them the buzzzz...
dave dove
Why Aikido?
Excuse me all,
why don't everybody try GOMEZ instead of Aikido?
My best results for an Hybrid Amp are Gomez made by 12AY7 + 6SN7.
0.3 % THD+N at 40 volt r.m.s. output on 18 K load!
Aikido has a kind of out-in feedback, Gomez doesn't, only local F.b.
Gomez is more musical also for that, is more like a little more complex SRPP.
And has a low output impedence.
And if you don't bypass the two cathode has NO CAPACITOR ON THE SIGNAL PATH (of course a part the output one).
Aikido as at least one!
Waiting for replies. Whishes...
Excuse me all,
why don't everybody try GOMEZ instead of Aikido?
My best results for an Hybrid Amp are Gomez made by 12AY7 + 6SN7.
0.3 % THD+N at 40 volt r.m.s. output on 18 K load!
Aikido has a kind of out-in feedback, Gomez doesn't, only local F.b.
Gomez is more musical also for that, is more like a little more complex SRPP.
And has a low output impedence.
And if you don't bypass the two cathode has NO CAPACITOR ON THE SIGNAL PATH (of course a part the output one).
Aikido as at least one!
Waiting for replies. Whishes...
Good question...and ideally one should build a Gomez and compare in one's system...but I read this part on John's site
"Avoid thinking in terms of "best" in general and think in terms of best in a particular circuit. Thus, we might think of using a Gomes amplifier as an output-tubes driver; the XPP amplifier, as a low-impedance-load amplifier, for such loads as headphones; the SRPP, as cheap/simple push-pull amplifier for a fixed load impedance; and the Aikido amplifier, as a preamplifier or line stage amplifier. "
http://www.tubecad.com/2004/blog0016.htm#MoreGomez
"Avoid thinking in terms of "best" in general and think in terms of best in a particular circuit. Thus, we might think of using a Gomes amplifier as an output-tubes driver; the XPP amplifier, as a low-impedance-load amplifier, for such loads as headphones; the SRPP, as cheap/simple push-pull amplifier for a fixed load impedance; and the Aikido amplifier, as a preamplifier or line stage amplifier. "
http://www.tubecad.com/2004/blog0016.htm#MoreGomez
Hi!
I already read that passage on tubecad, and I partially agree.
Here It seems to me we are not talking about driving headphones...
Anyway my experiences are that if you need to drive BJT, Mosfet or power Vacuum tubes
it's better to have a stage with 100 or less ohm output impedance obtained by the most SIMPLY and NOT feedback stage (so the best in musicality) and with the smallest number of capacitor on signal path,
than have a driver stage with 10 ohm or less out impedence, but with feedbak and capacitors everywhere...
So SRPP is simply, no cap, low f.b. but a relatively hi output impedence (depending from the tube, of course)
Gomez implemented for exemple by an hi gaing tube in the first part of the stage and an hi power tube in the second part you have simplicity, no cap, low f.b. comparable to SRPP.
Another solution like a driver, I think less musical, but still easier, no cap, low f.b., but stil better than AIKIDO (that have feedback everywhere) could be one stage made by an srpp of an hi gain tube (ex. 12AX7 OR 12AY7) linked to a cathode follower of, for example, 6sn7.
You have the best linearity you want (the tubes I have mentioned are between the best in linearity) without any need of feedback. Of course you must use 400-500 volt to power the stage.
Those are my decades experiences, lots of mesurements and lots of listening (with friends).
Wishes
G.M.
I already read that passage on tubecad, and I partially agree.
Here It seems to me we are not talking about driving headphones...
Anyway my experiences are that if you need to drive BJT, Mosfet or power Vacuum tubes
it's better to have a stage with 100 or less ohm output impedance obtained by the most SIMPLY and NOT feedback stage (so the best in musicality) and with the smallest number of capacitor on signal path,
than have a driver stage with 10 ohm or less out impedence, but with feedbak and capacitors everywhere...
So SRPP is simply, no cap, low f.b. but a relatively hi output impedence (depending from the tube, of course)
Gomez implemented for exemple by an hi gaing tube in the first part of the stage and an hi power tube in the second part you have simplicity, no cap, low f.b. comparable to SRPP.
Another solution like a driver, I think less musical, but still easier, no cap, low f.b., but stil better than AIKIDO (that have feedback everywhere) could be one stage made by an srpp of an hi gain tube (ex. 12AX7 OR 12AY7) linked to a cathode follower of, for example, 6sn7.
You have the best linearity you want (the tubes I have mentioned are between the best in linearity) without any need of feedback. Of course you must use 400-500 volt to power the stage.
Those are my decades experiences, lots of mesurements and lots of listening (with friends).
Wishes
G.M.
Nope..but John suggested XPP for that purpose...the way I read it..
I find your experienes very interesting...thanks for chipping in....I especially liike reading about your listening experiences as low distortion etc...only tell us part of the story....I might just try Gomez for my son's SE el34 as driver stage.
Hi to all,
I just finished (finally) my Aikido line stage - it is almost the same as in the sch on the first post of this thread that Bas attached only the tubes are 6n6p in both stages and cathode resistors are 470R (also in both stages)......
Well - there are a few other values changed in that sch (but nothing to worry - grid resistors are 1k and resistor dividers are 1m (not 100k) accept the ones with cap in series)....
The problem
When I toke measurements to determine if everything is o.k. I have noticed that one channel has perfect voltage splitting accros those 1m resistors and the other doesn't. The currents are in assumed levels (arround 10ma) in borh stages - and I toke measurements on every cathode resistor to determine the currents - they are o.k.
But the non simetric splitting gave me a headache. So I started to substitute tubes and determined that it is not the circuit that is making the non-simetry but the tube in the first stage of the channel with non-simetry. When I substitute the second stage tube with the first stage tube in that channel simetry is almost o.k. and when I turn them back again it is not.
How can this be - when I have those resistors dividers in the first stage (1M in series with 1M) and in the second also (the same as in the first stage)?????
Any ideas.....
best regards
sunny
I just finished (finally) my Aikido line stage - it is almost the same as in the sch on the first post of this thread that Bas attached only the tubes are 6n6p in both stages and cathode resistors are 470R (also in both stages)......
Well - there are a few other values changed in that sch (but nothing to worry - grid resistors are 1k and resistor dividers are 1m (not 100k) accept the ones with cap in series)....
The problem
When I toke measurements to determine if everything is o.k. I have noticed that one channel has perfect voltage splitting accros those 1m resistors and the other doesn't. The currents are in assumed levels (arround 10ma) in borh stages - and I toke measurements on every cathode resistor to determine the currents - they are o.k.
But the non simetric splitting gave me a headache. So I started to substitute tubes and determined that it is not the circuit that is making the non-simetry but the tube in the first stage of the channel with non-simetry. When I substitute the second stage tube with the first stage tube in that channel simetry is almost o.k. and when I turn them back again it is not.
How can this be - when I have those resistors dividers in the first stage (1M in series with 1M) and in the second also (the same as in the first stage)?????
Any ideas.....
best regards
sunny
yeap- they are fine - every bloody resistors is fine and within the specs.....
and yet - I have the non-symetry..... i am waiting for another 4 tubes - so i would substitute that one that is causing the problem (if it is causing the problem that is)...... i don't get how this could be possible - i will check every resistor again tomorrow - maybe i've missed something......
regards
sunny
and yet - I have the non-symetry..... i am waiting for another 4 tubes - so i would substitute that one that is causing the problem (if it is causing the problem that is)...... i don't get how this could be possible - i will check every resistor again tomorrow - maybe i've missed something......
regards
sunny
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.