Hi Argo,
I wrote:
You answered:
But that isn´t so much wasted power as it looks in the first moment, since: the 6as7 has 255V across it and probably runs at maybe 12 watts PD which means maybe 47mA plate current.
Now, Pd Rk = 135V * 0,047A = 6,4 watts.
Nevertheless, quite a very strange operation point for the 6as7g:
- very high Ea,
- very low Ia
- very high Rload/Rinternal ratio: Ra for single tube in PP class A is Raa/2, thus 2,5k in this circuit, which is about 11 times the internal (plate-) resistance.
Usually, for triodes one uses a ratio of about 3 times. But that is only a rule of thumb; I myself run a trioded EL34 SE w/ high voltage & low current at 10k with a very satisfying sound, very low THD and god DF.
Tom
I wrote:
- burning only 135V in the cathode resistors
You answered:
argo said:Well, there is hardly ever free lunch
But that isn´t so much wasted power as it looks in the first moment, since: the 6as7 has 255V across it and probably runs at maybe 12 watts PD which means maybe 47mA plate current.
Now, Pd Rk = 135V * 0,047A = 6,4 watts.
Nevertheless, quite a very strange operation point for the 6as7g:
- very high Ea,
- very low Ia
- very high Rload/Rinternal ratio: Ra for single tube in PP class A is Raa/2, thus 2,5k in this circuit, which is about 11 times the internal (plate-) resistance.
Usually, for triodes one uses a ratio of about 3 times. But that is only a rule of thumb; I myself run a trioded EL34 SE w/ high voltage & low current at 10k with a very satisfying sound, very low THD and god DF.
Tom
Brett said:
That is exactly the point *smile*. No, I don't want to tell anyone about it , but that is one of the main ideas I wanted to realize in this project. Doing it completely without SS devices... What values would you suggest for a slightly higher gain? Just to make sure...
How far can I go if it isn't enough?This is generally my opinion too. Problem is that it will be difficult to add a preamp later. The only way would be to make a test setup to find out if it is enough gain. Later adding a preamp would mean expensive modifications of housing etc, or adding a separate preamp, which would look strange when the main amplifier is already equipped with input selection / volume control
...Thats what I already thought about. Am I right in thinking that it is simply realized by starting the heat-up of the diodes with a certain delay? (Without using semiconductors, this will probably be done manually via switch)
Would you mind giving schematics for your power supply? Then I can decide if I modify it or use it directly as it is
...Many Greetings
Andreas
No brainer here.......
Build the Eric Kingsbury triode connected 6V6 amp that is often called the 'poinz' amp. Do a Google search to find schematic. I built a PPP triode connected version.
Use 10K primary audio trannies for two tubes or 5500-6300 K for a quad. Unloading the primary makes for best sonics. Change the 5965 to a Raytheon 6CG7 (direct drop-in) & never look back. Use AuriCap coupling caps including the phase splitter 1-uF cap to ground.
Triode connected pair is about 6-watts or a quad is 12 watts out. I like Sylvania 6V6GT or believe ot or not GE 6V6GTA. The metal 6V6s sound poor. Save cash & buy Sylvania 7C5 that are a 6V6 in a loctal base. The NOS Sylvania 7C5 are $4-5 each. I once bought 10 NOS for $25.
The amps rival my custom PP 45s with expensive custom MQ iron.
Build the Eric Kingsbury triode connected 6V6 amp that is often called the 'poinz' amp. Do a Google search to find schematic. I built a PPP triode connected version.
Use 10K primary audio trannies for two tubes or 5500-6300 K for a quad. Unloading the primary makes for best sonics. Change the 5965 to a Raytheon 6CG7 (direct drop-in) & never look back. Use AuriCap coupling caps including the phase splitter 1-uF cap to ground.
Triode connected pair is about 6-watts or a quad is 12 watts out. I like Sylvania 6V6GT or believe ot or not GE 6V6GTA. The metal 6V6s sound poor. Save cash & buy Sylvania 7C5 that are a 6V6 in a loctal base. The NOS Sylvania 7C5 are $4-5 each. I once bought 10 NOS for $25.
The amps rival my custom PP 45s with expensive custom MQ iron.
Well,
I think this thread has reached his aim, I'll probably build my amp based on the Wright PP1 schematic. Many thanks for your ideas and comments, they were quite helpful for a tube newbie ...
Of course I'm going to include some modifications as tube rectification and a tube based constant current source. But I'll think it makes more sense to discuss these topics in separate threads where they can be found easier by others with the same questions. If there is enough interest, I'll also start a thread concerning the progress in designing and building "my" amp with regular updates...
thanks so far, I'll return with more questions as soon as the first ideas are written down...
Greetings
Andreas
I think this thread has reached his aim, I'll probably build my amp based on the Wright PP1 schematic. Many thanks for your ideas and comments, they were quite helpful for a tube newbie
...Of course I'm going to include some modifications as tube rectification and a tube based constant current source. But I'll think it makes more sense to discuss these topics in separate threads where they can be found easier by others with the same questions. If there is enough interest, I'll also start a thread concerning the progress in designing and building "my" amp
with regular updates...thanks so far, I'll return with more questions as soon as the first ideas are written down...
Greetings
Andreas
Rundmaus said:If there is enough interest, I'll also start a thread concerning the progress in designing and building "my" amp
Yes... do post a link to that thread. I have a number of donors that are headed towards amps inspired by the PP1C and would be interested in your results.
dave
Sorry for late reaction; my server again . . .
As Rundmaus said the thread has reached its aim and I don't want to hijack for sidelines or have the last word, but to reply if only as a courtesy.
No, Brett, and I think I am a little off page here - what exactly do you mean by a differential output stage? As I gathered the point was to get zero dc component in the output transformer by inserting a CCS in either output tube cathode; that is not differential. But no not lately, and I fear that my poor ears hardly reach 8 KHz these days (ravages of age!) so small nuances are not likely to be audible to me any longer (sob-sob).
I certainly don't dispute that AWs amplifier is good (regarding awards), just that according to other experiences the tight dc balance does not seem to be essential to excellence. Again, should we maintain that, we are then stuck with, at the other end, things like the "On-Gaku", etc. which folks also rave about and pay a house's price for, despite lots of dc on the transformer. (And no, that is NOT my preference.) I just thought that if I read Rundmouse correctly he is new in this business, so I tried to spread the scene a little wider.
(Re philosophy - subjectivity: Fair comment, Brett. But I think one must define subjectivity. It is not just observation but also conclusion. Thus reading a DVM may be "subjective", but one can hardly interpret a digital reading of 1.34V in more than one way. On the other hand we all know how diverse opinions can be in listening tests.)
But one is glad that Rundmaus was helped by good suggestions here; the above is just a sideline.
As Rundmaus said the thread has reached its aim and I don't want to hijack for sidelines or have the last word, but to reply if only as a courtesy.
Brett said:
No, Brett, and I think I am a little off page here - what exactly do you mean by a differential output stage? As I gathered the point was to get zero dc component in the output transformer by inserting a CCS in either output tube cathode; that is not differential. But no not lately, and I fear that my poor ears hardly reach 8 KHz these days (ravages of age!) so small nuances are not likely to be audible to me any longer (sob-sob).
I certainly don't dispute that AWs amplifier is good (regarding awards), just that according to other experiences the tight dc balance does not seem to be essential to excellence. Again, should we maintain that, we are then stuck with, at the other end, things like the "On-Gaku", etc. which folks also rave about and pay a house's price for, despite lots of dc on the transformer. (And no, that is NOT my preference.) I just thought that if I read Rundmouse correctly he is new in this business, so I tried to spread the scene a little wider.
(Re philosophy - subjectivity: Fair comment, Brett. But I think one must define subjectivity. It is not just observation but also conclusion. Thus reading a DVM may be "subjective", but one can hardly interpret a digital reading of 1.34V in more than one way. On the other hand we all know how diverse opinions can be in listening tests.)
But one is glad that Rundmaus was helped by good suggestions here; the above is just a sideline.
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