Can someone tell me what value resistors to use so that I can use 6922 tubes in the Aikido, or show me how to calculate the values. I have never deigned anything tube before so I am clueless as to what to do.
Has anyone tried 6922 in their Aikido, what is the sound like compared to other tubes? I ask because I have a bunch of 6922 lying around and I am trying to control the urge of buying new tubes when I dont need any.
Thanks yall
Lawrence
Has anyone tried 6922 in their Aikido, what is the sound like compared to other tubes? I ask because I have a bunch of 6922 lying around and I am trying to control the urge of buying new tubes when I dont need any.
Thanks yall
Lawrence
Lawrence:
220 ohms on all the cathodes, 47K ohms on the grid of the input section, 300 ohms on the grids of the second stage of both the upper and lower section(where the PS noise is injected into the grid of the lower section). This value works for 6922, 6DJ8's, 6n1P's. I've built it, I like it.
Good luck,
dr._sleep
220 ohms on all the cathodes, 47K ohms on the grid of the input section, 300 ohms on the grids of the second stage of both the upper and lower section(where the PS noise is injected into the grid of the lower section). This value works for 6922, 6DJ8's, 6n1P's. I've built it, I like it.
Good luck,
dr._sleep
If I may be bold and ask why the 220 ohm resistors instead of the 430/432 value? I am using the 6N1P with the 432 ohm resistor and getting 1.55 volts across the cathode resistor for 3.58mA. Is the value incorrect? If so would you mind explaining?
I am curious as to why my voltage is higher than what is listed. The schematic shows 1.2 volts using a 430 ohm resistor, I have 1.555 with a 432 ohm.
I have 10 mA running thru the second stage with a 5687.
I am curious as to why my voltage is higher than what is listed. The schematic shows 1.2 volts using a 430 ohm resistor, I have 1.555 with a 432 ohm.
I have 10 mA running thru the second stage with a 5687.
I've substituted these tube types (6922, 6DJ8, 6N1P) in the front end of the following schematic:
They have different operating points, and each has a desirable tone in this circuit. An advantage of the Aikido is that these triodes can be sub'd without having to adjust the cathode and anode resistors.
The 5876 has a different pinout and a hungry heater circuit, the aforementioned tubes do not sub in this position.
dr._sleep
An externally hosted image should be here but it was not working when we last tested it.
They have different operating points, and each has a desirable tone in this circuit. An advantage of the Aikido is that these triodes can be sub'd without having to adjust the cathode and anode resistors.
The 5876 has a different pinout and a hungry heater circuit, the aforementioned tubes do not sub in this position.
dr._sleep
bill
i happened to have a linestage with psu and four sockets
so i just pulled the wiring and redid it
it is hard-wired and very messy
but very quiet
i'm using 430R on all valves
6n1p and 6n6p
lawbadman
i have used 6922 in all four positions
and only in first position
with 430R cathode
they sounded fine
mullards sounded best
you may like them.....
i prefer how i've got it now
dr.sleep
i'm not so technical
what's going on there?
you got global feedback?
and a big cap with optx
what's it for?
i tried 5:1 optx
JB suggested i reduce output cap by one fifth
but it hummed
my psu is onboard see.....
do you suggest 220R all round for a linestage?
you've also got 250V HT
think i may try this....
james
i guess i'll have to look at those curves....
dave dove
i happened to have a linestage with psu and four sockets
so i just pulled the wiring and redid it
it is hard-wired and very messy
but very quiet
i'm using 430R on all valves
6n1p and 6n6p
lawbadman
i have used 6922 in all four positions
and only in first position
with 430R cathode
they sounded fine
mullards sounded best
you may like them.....
i prefer how i've got it now
dr.sleep
i'm not so technical
what's going on there?
you got global feedback?
and a big cap with optx
what's it for?
i tried 5:1 optx
JB suggested i reduce output cap by one fifth
but it hummed
my psu is onboard see.....
do you suggest 220R all round for a linestage?
you've also got 250V HT
think i may try this....
james
i guess i'll have to look at those curves....
dave dove
D.D.:
John Broskie was nice enough to slip this schematic to me when I inquired about using the Aikido for a headphone amp. Just so happens it does double duty after adding a switch for feedback in or out; a OTL out, with and without feedback for some 600 ohm AKG's and a 32 ohm out via transformer with and without feedback for my Sennheiser 595's, and/or a killer preamp driving 2 EL84 based monoblocks. Dead quiet and creamy. I don't migrate to the feedback mode unless the source recording sucks, ala Sting's latest.
dr._sleep
John Broskie was nice enough to slip this schematic to me when I inquired about using the Aikido for a headphone amp. Just so happens it does double duty after adding a switch for feedback in or out; a OTL out, with and without feedback for some 600 ohm AKG's and a 32 ohm out via transformer with and without feedback for my Sennheiser 595's, and/or a killer preamp driving 2 EL84 based monoblocks. Dead quiet and creamy. I don't migrate to the feedback mode unless the source recording sucks, ala Sting's latest.
dr._sleep
The tubes would just bias up differently around 9 milliamps with the lower value resistors, but no problem as long as the operating points are not unjust.
A resistor value around 100 ohms and 220 B+ results in a plate dissipation of 1.85 watts shurely over the maximum for 6922's, 6DJ8's. Gotta love that TubeCad.
dr. sleep
A resistor value around 100 ohms and 220 B+ results in a plate dissipation of 1.85 watts shurely over the maximum for 6922's, 6DJ8's. Gotta love that TubeCad.
dr. sleep
I was just looking at the datasheet for the 6922 and saw that Va is 90v. On the Aikido circuit diagram the voltage across each section of the tube will be slightly less than 110v. Isnt that too much voltage for the tube or am I misunderstanding (which I probably am)? 
Can someone clarify?
Thanks
Lawrence
Can someone clarify?
Thanks
Lawrence
Aikido for 32 ohm cans
I'm quite interested in Dr. Sleep's circuit (or rather the one that John Broskie sent to Dr. Sleep) -- it's the first instance I've seen of an Aikido circuit that can drive 32-ohm headphones. He PMd it to me a while ago and I'm considering it -- the optional global feedback seems like a nice switchable option.
I currently have an all-6SN7 Aikido linestage I hardwired (I have a good collection of 6SN7s, that's the only reason).... It's become my reference linestage, I adore it to death -- yet I would love to be able to rig it, with the proper OPT, to drive a 32-ohm headphone load (I'm a dedicated Grado freak). Yet there doesn't seem to be a transformer in existence that can make this possible. Any thoughts?
I'm quite interested in Dr. Sleep's circuit (or rather the one that John Broskie sent to Dr. Sleep) -- it's the first instance I've seen of an Aikido circuit that can drive 32-ohm headphones. He PMd it to me a while ago and I'm considering it -- the optional global feedback seems like a nice switchable option.
I currently have an all-6SN7 Aikido linestage I hardwired (I have a good collection of 6SN7s, that's the only reason).... It's become my reference linestage, I adore it to death -- yet I would love to be able to rig it, with the proper OPT, to drive a 32-ohm headphone load (I'm a dedicated Grado freak). Yet there doesn't seem to be a transformer in existence that can make this possible. Any thoughts?
Hi,
The Sowter 8665 should be suitable for this.
http://www.sowter.co.uk/acatalog/SOWTER_HEADPHONE_TRANSFORMERS_29.html
I was just considering getting a pair for a similar project myself.
Pretty expensive, though, at £51.72 a pop...
Morgan
The Sowter 8665 should be suitable for this.
http://www.sowter.co.uk/acatalog/SOWTER_HEADPHONE_TRANSFORMERS_29.html
I was just considering getting a pair for a similar project myself.
Pretty expensive, though, at £51.72 a pop...
Morgan
Aikido, a few measurments
Hi all,
If anyone is interested in how the Aikido looks, as built, with the boards that Bas and Bonny provided us with. Well here are a few tidbits.
First a disclaimer and some history. I am not a tube Guru, just an engineer. I am plotting the load lines for this circuit and I’m still not sure they look right, but they do work well and I know enough to tell that tubes are not in death mode .
More of that on a different post. (tube gurus sharpen your pencils, thank you)
Anyway, I built one with 6n1p in the front end and 6n6~ (I just can’t get the hang of the Russian alphabet), as the second tube. My lashed up power supply only netted 170V.
Oh well, lets try it anyway.
Sounds OK. Not world class, but the dynamics are very promising.
I dust off the scope (literally) and can see that one side of a 1k sine wave doesn’t match the other. Nothing harsh, just nolinearity. A check of the bias shows .8v at the grid with a 430 Ohm Resistor . That seem a bit too close to 0v. time to fix the power supply.
I do so.
Now I have ~240 B+ and more like 1.6V at the grids. Thit's more like it .
A check of the inputs and outputs. Shows not much to report. They look pretty much the same. I fiddled With the scope controls , to overlay one trace over the other. They look much the same, except one is 2vp-p and the other is 40vp-p.
So, what do you think?
In this photo the top trace is the input, 2V P-P . 40khz. Scope set, at 1V /division
Lower trace 20v p-p scope set at 10v/ division @ 40khz
Remember this is 40k not 1k If anyone has tips as to present this better, please help…John
Hi all,
If anyone is interested in how the Aikido looks, as built, with the boards that Bas and Bonny provided us with. Well here are a few tidbits.
First a disclaimer and some history. I am not a tube Guru, just an engineer. I am plotting the load lines for this circuit and I’m still not sure they look right, but they do work well and I know enough to tell that tubes are not in death mode .
More of that on a different post. (tube gurus sharpen your pencils, thank you)
Anyway, I built one with 6n1p in the front end and 6n6~ (I just can’t get the hang of the Russian alphabet), as the second tube. My lashed up power supply only netted 170V.
Oh well, lets try it anyway.
Sounds OK. Not world class, but the dynamics are very promising.
I dust off the scope (literally) and can see that one side of a 1k sine wave doesn’t match the other. Nothing harsh, just nolinearity. A check of the bias shows .8v at the grid with a 430 Ohm Resistor . That seem a bit too close to 0v. time to fix the power supply.
I do so.
Now I have ~240 B+ and more like 1.6V at the grids. Thit's more like it .
A check of the inputs and outputs. Shows not much to report. They look pretty much the same. I fiddled With the scope controls , to overlay one trace over the other. They look much the same, except one is 2vp-p and the other is 40vp-p.
So, what do you think?
In this photo the top trace is the input, 2V P-P . 40khz. Scope set, at 1V /division
Lower trace 20v p-p scope set at 10v/ division @ 40khz
Remember this is 40k not 1k If anyone has tips as to present this better, please help…John
Attachments
It's nice to see the Aikido Headphone/Preamp circuit John Broskie slipped me mentioned again in a posting.
The Sowter transformers are well worth the price, even higher by the time you get them to the US. I use Senn's 895's (50 ohms)with great results.
John, the picture you posted of your scope is exactly what I get using a variety of frequencies, and finding power supply noise at the outputs is next to impossible.
If I needed another or someone wanted a tube pre/headphone amplifier, I build it again.
The only change I recently impemented was to elevate the heater voltage 50v, but it did not change the sound or the scope tracing.
dr._sleep
The Sowter transformers are well worth the price, even higher by the time you get them to the US. I use Senn's 895's (50 ohms)with great results.
John, the picture you posted of your scope is exactly what I get using a variety of frequencies, and finding power supply noise at the outputs is next to impossible.
If I needed another or someone wanted a tube pre/headphone amplifier, I build it again.
The only change I recently impemented was to elevate the heater voltage 50v, but it did not change the sound or the scope tracing.
dr._sleep
I was trouble shooting some noise problems in my Aikido Headphone/Preamp (hissing and crackling). Found a couple of suspect, cold solder joints at the 20uF caps out to trannys and transformerless outs.
I had a couple of .47uF Auricaps and put them in place of the 20uF Solens fulling expecting to lose the bottom end. This did not happen and the frequency balance semmed to actually improve, certainly the back ground became much darker and silent, better highs, just a small amount of vocal simbalance on some newer CD's. The older AAD o ADD recording were perfect.
This smaller value means that I can put some serious paper in oil, copper or silver caps which I prefer at a reasonable price.
Anyone know the math behind selecting this cap value. Does this cap form a high pass filter with the load. And what is the calculated load? Thanks in advance for an answer.
dr._sleep
An externally hosted image should be here but it was not working when we last tested it.
I had a couple of .47uF Auricaps and put them in place of the 20uF Solens fulling expecting to lose the bottom end. This did not happen and the frequency balance semmed to actually improve, certainly the back ground became much darker and silent, better highs, just a small amount of vocal simbalance on some newer CD's. The older AAD o ADD recording were perfect.
This smaller value means that I can put some serious paper in oil, copper or silver caps which I prefer at a reasonable price.
Anyone know the math behind selecting this cap value. Does this cap form a high pass filter with the load. And what is the calculated load? Thanks in advance for an answer.
dr._sleep
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