dhaen said:
Mmm, let me guess........More power into the speaker?
How so? You're not increasing either gain, or current.
Because the energy is not being wasted in the cathode component.
If it were a resistor, more than half your power would be bured up as heat.
But I cannot send any more voltage to the speaker, since the gain is always less than one - no matter how big a resistor or choke I put there.
Am I thinking about this wrong? It's possible...
Am I thinking about this wrong? It's possible...
You send more voltage to the speaker for 2 reasons:
1) The inductor "rings", doulbling the voltage.
2) Less voltage is dropped acroos the Rint of the valve.
Rint ;I'm making 'em up as I go along😉 I mean the equivalent internal resistance if the valve.🙂
1) The inductor "rings", doulbling the voltage.
2) Less voltage is dropped acroos the Rint of the valve.
Rint ;I'm making 'em up as I go along😉 I mean the equivalent internal resistance if the valve.🙂
Hi Frank,
Some Japanese site, while I was looking for a 6c33SE schematic.
I dread to think how unstable that bunch will go as they age.
There are tales of OTL genocide with these you know.
Cheers,
Some Japanese site, while I was looking for a 6c33SE schematic.
I dread to think how unstable that bunch will go as they age.
There are tales of OTL genocide with these you know. Cheers,
OUTRAGEOUS OTLS
Hi,
Thanks John.
I am curious to know how they drive a bunch of valves like the 6C33C.
Just imagine having an amp like that in your living room and one of the valves goes South....
Gives me the creeps,I'll stick to my old faithful 6AS7 family of valves.
Cheers,😉
Hi,
Thanks John.
I am curious to know how they drive a bunch of valves like the 6C33C.
Just imagine having an amp like that in your living room and one of the valves goes South....
Gives me the creeps,I'll stick to my old faithful 6AS7 family of valves.
Cheers,😉
Frank,
That's a similar problem our colleagues over in the SS forum have.😉
Cheers,
Do you mean the combined Miller capacitance?
That's a similar problem our colleagues over in the SS forum have.😉
Cheers,
Hello everyone,
Frank, I have been dreaming about that Belgian Beer. Looks like I have not earned it. So far I have not come up with any new ideas for eliminating the cap at the output in a SE OTL.
There is of course a way….because there are always exceptions to any rule. This will involve two tracking power supplies with the load connected between the grounds of power supplies. This is a variation of the circlotron approach. Has anyone tried this approach? Any comments?
Joel, after a lengthy period away from this forum, I logged in yesterday. If you wish, I can model your circuit and come up with an approximate output impedance. Have you already carried out this exercise?
By the way, I have been optimising my transformer coupled amp using 6C41C. At 150V across the tube and 150mA quiescent current, the rp is of the order of 250 ohms. Very close to 6080 specs but with twice the idle current.
Mohan
Frank, I have been dreaming about that Belgian Beer. Looks like I have not earned it. So far I have not come up with any new ideas for eliminating the cap at the output in a SE OTL.
There is of course a way….because there are always exceptions to any rule. This will involve two tracking power supplies with the load connected between the grounds of power supplies. This is a variation of the circlotron approach. Has anyone tried this approach? Any comments?
Joel, after a lengthy period away from this forum, I logged in yesterday. If you wish, I can model your circuit and come up with an approximate output impedance. Have you already carried out this exercise?
By the way, I have been optimising my transformer coupled amp using 6C41C. At 150V across the tube and 150mA quiescent current, the rp is of the order of 250 ohms. Very close to 6080 specs but with twice the idle current.
Mohan
RE:OTL.
Hi,
Hey Mohan,
Good to see you back on board.
Yes, but that is how most do it for PP OTLs and it works fine.
Can't really imagine how that would work on an SE stage though.
Adorn it with a good PSU and I can already hear it rock the house.
Bas H. are you there?
Ciao,😉
Hi,
Hey Mohan,
Good to see you back on board.
Yes, but that is how most do it for PP OTLs and it works fine.
Can't really imagine how that would work on an SE stage though.
Adorn it with a good PSU and I can already hear it rock the house.
Bas H. are you there?
Ciao,😉
Class A OTL
Bruce of Transcendent sound has just come out with a true class A OTL. Uses 6H30PI driver and 6C19PI power tube. Puts out 1.5 watts stereo or can be bridged for 4 watts. The kit price is very reasonable. The only thing I did not like about it was it had a cap at the output. On his message board he said it could be taken out with a negative supply. But, he choose not do it that way because it made the design much more complex. This might be a good design to copy and improve.
He also explains in his message board and in his written area why most OTLS claim to be class A and are in fact not. Reading between the lines he really says none are true class A. That he has seen so far.
I listened to the Joule Electra OTL amps. They Sounds great. But the big Russian 633C tube has real quality problems and is not cheap.
Here is the link to Burce's amp.
http://www.transcendentsound.com/single ended.htm
Bruce of Transcendent sound has just come out with a true class A OTL. Uses 6H30PI driver and 6C19PI power tube. Puts out 1.5 watts stereo or can be bridged for 4 watts. The kit price is very reasonable. The only thing I did not like about it was it had a cap at the output. On his message board he said it could be taken out with a negative supply. But, he choose not do it that way because it made the design much more complex. This might be a good design to copy and improve.
He also explains in his message board and in his written area why most OTLS claim to be class A and are in fact not. Reading between the lines he really says none are true class A. That he has seen so far.
I listened to the Joule Electra OTL amps. They Sounds great. But the big Russian 633C tube has real quality problems and is not cheap.
Here is the link to Burce's amp.
http://www.transcendentsound.com/single ended.htm
I DIG A GRAVE...
Hi,
Let him talk when he knows the difference between Class A and B.
So..it's not even a true OTL, not even OCL?
Do they even know the nomenclature? Guess not...
Hey, modern manufacture caps aren't that bad at all, lets just call a spade a spade though??
Do they really think we're all retarded?
Show me one OTL design claiming to operate in Class A and I'll prove you in a second that it doesn't. ********.
On a per watt basis it's about as cheap as you can get and still have very high quality....
It's about time someone gaps the twenty year lapse between Europe and the US on this.
Prejudice rulez,😀
Hi,
Let him talk when he knows the difference between Class A and B.
So..it's not even a true OTL, not even OCL?
Do they even know the nomenclature? Guess not...
Hey, modern manufacture caps aren't that bad at all, lets just call a spade a spade though??
Do they really think we're all retarded?
Show me one OTL design claiming to operate in Class A and I'll prove you in a second that it doesn't. ********.
On a per watt basis it's about as cheap as you can get and still have very high quality....
It's about time someone gaps the twenty year lapse between Europe and the US on this.
Prejudice rulez,😀
Hi,
Short of sounding as if I've an axe to grind here ( which I really don't) :
I don't have trouble with the 6C33C, I do encounter trouble with septar sockets that have trouble with the heater currents...
Get the Johnsons if you can find them.
Don't forget this is a formidable regulator tube NOT intended for audio service...
Let's not forget either that his a BIG MF powerhouse which happens to be pretty linear and contrary to your thinking can be gad for a tenner and less...much less.
Tolerance isn't the major concern when designing regulator tubes and you'll encounter similar problems with most regulator tubes except perhaps the TFK ED8000.
Cheers,😉
Short of sounding as if I've an axe to grind here ( which I really don't) :
I don't have trouble with the 6C33C, I do encounter trouble with septar sockets that have trouble with the heater currents...
Get the Johnsons if you can find them.
Don't forget this is a formidable regulator tube NOT intended for audio service...
Let's not forget either that his a BIG MF powerhouse which happens to be pretty linear and contrary to your thinking can be gad for a tenner and less...much less.
Tolerance isn't the major concern when designing regulator tubes and you'll encounter similar problems with most regulator tubes except perhaps the TFK ED8000.
Cheers,😉
Septars
Hi Frank ,
I also encountered socket problems with 6C33 , the heat conducted via the filament pins can make the plating blacken . I first used Russian septar sockets , the valves needed reseating every now and again . Eventually I used teflon septars , to get rid of the heat at the filament pins I stripped about 3cm of the filament connecting wire and wrapped around the solder contacts . Once soldered these made little 'heatsinks' , never had problems after that 🙂
316a
fdegrove said:
Hi Frank ,
I also encountered socket problems with 6C33 , the heat conducted via the filament pins can make the plating blacken . I first used Russian septar sockets , the valves needed reseating every now and again . Eventually I used teflon septars , to get rid of the heat at the filament pins I stripped about 3cm of the filament connecting wire and wrapped around the solder contacts . Once soldered these made little 'heatsinks' , never had problems after that 🙂
316a
Hi,
Thanks for the tip.
I've no idea as to where to source PTFE septar sockets though...
Let's just hope it works for the ceramic Russian septars just the same...
Just out of curiosity, are you running the 6C33Cs OTL or OPT PP?
Cheers, 😉
Thanks for the tip.
I've no idea as to where to source PTFE septar sockets though...
Let's just hope it works for the ceramic Russian septars just the same...
Just out of curiosity, are you running the 6C33Cs OTL or OPT PP?
Cheers, 😉
Septars cntd...
Hi Frank ,
I have about 150 of the septars in case you ever need any 😉 I didn't use either of the topologies : I used stacked SEPP 6C33 with the lower valve running fixed bias at about 250mA 180V . I wasn't too keen running the things harder , had a nasty 'accident' where on one channel a 6C33 went 'bye bye' after running it at 55w . At 45w the things are happy three-titted monsters 🙂
316a
fdegrove said:
Hi Frank ,
I have about 150 of the septars in case you ever need any 😉 I didn't use either of the topologies : I used stacked SEPP 6C33 with the lower valve running fixed bias at about 250mA 180V . I wasn't too keen running the things harder , had a nasty 'accident' where on one channel a 6C33 went 'bye bye' after running it at 55w . At 45w the things are happy three-titted monsters 🙂
316a
Paul, thanks for waking me. I have a lot of respect for Bruce ever since I read his article in Glass Audio some years ago. From memory, this was a no nonsense straight forward design based on Futterman topology. The power supply could be better.
My earlier post in this thread states my present preoccupation. So far I have not come up with any new ideas for eliminating the cap at the output in a SE OTL. Apologies Frank.
6C19PI is more or less equivalent to one half of a 6AS7. 6H30PI needs to be driven.
All of us know that a high transconductance tube such as 6C33C needs a large cathode area. This is because manufacturers use the same oxide coating on the cathodes. More R&D is required. But then again the Russians are waking up to current trends such as scale of economy, market volume and hence the returns in dollar terms. Sense of perfectionism and the pride that goes along with it has temporarily disappeared over the past two decades.
Thickness of cathode coating is not uniform and this translates to uneven emission. How do we know that the entire cathode area is uniformly heated? Directly heated triodes have similar problems, non uniformities in the composition of the cathode (Thoriated Tungsten), pitting, contamination as the tube ages and so on.
All this gives us some sort of explanation on variabilities that are inherent in the manufacture of modern electron tubes. During my brief experiments in the early nineties, I preferred to operate the 6C33C at about 30W dissipation and at a transconductance of around 20mA/V.
Yes, the Russian Septar sockets do conduct heat. I had to mount spacers and suspend these sockets below the chassis. A fan would help but then all the effort that I put into a low noise power supply will become an exercise in vain!
316A, I would love to have some more of those sockets, but keep some spares. I have cracked quite a few when removing tubes while the sockets are rather hot.
Frank, have you had any experience with 13E1. I love the looks of this tube. No longer in production and spares are becoming hard to find. Should I believe this?
Mohan
My earlier post in this thread states my present preoccupation. So far I have not come up with any new ideas for eliminating the cap at the output in a SE OTL. Apologies Frank.
6C19PI is more or less equivalent to one half of a 6AS7. 6H30PI needs to be driven.
All of us know that a high transconductance tube such as 6C33C needs a large cathode area. This is because manufacturers use the same oxide coating on the cathodes. More R&D is required. But then again the Russians are waking up to current trends such as scale of economy, market volume and hence the returns in dollar terms. Sense of perfectionism and the pride that goes along with it has temporarily disappeared over the past two decades.
Thickness of cathode coating is not uniform and this translates to uneven emission. How do we know that the entire cathode area is uniformly heated? Directly heated triodes have similar problems, non uniformities in the composition of the cathode (Thoriated Tungsten), pitting, contamination as the tube ages and so on.
All this gives us some sort of explanation on variabilities that are inherent in the manufacture of modern electron tubes. During my brief experiments in the early nineties, I preferred to operate the 6C33C at about 30W dissipation and at a transconductance of around 20mA/V.
Yes, the Russian Septar sockets do conduct heat. I had to mount spacers and suspend these sockets below the chassis. A fan would help but then all the effort that I put into a low noise power supply will become an exercise in vain!
316A, I would love to have some more of those sockets, but keep some spares. I have cracked quite a few when removing tubes while the sockets are rather hot.
Frank, have you had any experience with 13E1. I love the looks of this tube. No longer in production and spares are becoming hard to find. Should I believe this?
Mohan
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