"how about the 50A-C10? are you familiar with it? i have both 50 and 6 volt versions......
the tube looks like a horizontal output tube with screens and beam formers connected to plate....making it a triode...."
This valve was used by Lux in the 38FD in the 50C-A10 version, as the two heaters wired in series ran of the 100 volt AC primary.
Yes it was an internally wired triode on a 12 pin socket, that is why you think Horizontal pentode nearly but not quiet.
The 6 volt was much rarer.
"hi, we will appreciate any contributions coming from you....
i was under the impression that the Luxmans were a Japanese design...
i have a collection of Japanese tubes, the 6rr8, 6ra8, dual triodes 6rhh1, 2 and 8 and i like them all....
i even have a Japanese equivalent of the gz34/5ar4, the 5g-k17 which has an output 25mA greater, if that meant anything..."
If you google me you will know that I spent 4 years working in the design lab at Lux Corporation in Osaka from end 72 to end 76.
The 3045 power valve I based on an existing NEC design with many modifications to get the performance I wanted, then had it internally connected as a triode.
As the Japanese were mad on triodes. The prototype of the amp I made with a switch to do Pentode the UL then Triode and no one could truly hear any difference.
I wanted to prove that the circuit and transformers have more influence on performance.
No one copies it because it is a complex circuit. I am driven by performance not BS.
As to other odd ball valves such as you list, I would only keep for servicing purposes not new designs.
Please spell Japanese with upper case 'J'. It is a name. and GZ34 not gz. Lazy typing?
the tube looks like a horizontal output tube with screens and beam formers connected to plate....making it a triode...."
This valve was used by Lux in the 38FD in the 50C-A10 version, as the two heaters wired in series ran of the 100 volt AC primary.
Yes it was an internally wired triode on a 12 pin socket, that is why you think Horizontal pentode nearly but not quiet.
The 6 volt was much rarer.
"hi, we will appreciate any contributions coming from you....
i was under the impression that the Luxmans were a Japanese design...
i have a collection of Japanese tubes, the 6rr8, 6ra8, dual triodes 6rhh1, 2 and 8 and i like them all....
i even have a Japanese equivalent of the gz34/5ar4, the 5g-k17 which has an output 25mA greater, if that meant anything..."
If you google me you will know that I spent 4 years working in the design lab at Lux Corporation in Osaka from end 72 to end 76.
The 3045 power valve I based on an existing NEC design with many modifications to get the performance I wanted, then had it internally connected as a triode.
As the Japanese were mad on triodes. The prototype of the amp I made with a switch to do Pentode the UL then Triode and no one could truly hear any difference.
I wanted to prove that the circuit and transformers have more influence on performance.
No one copies it because it is a complex circuit. I am driven by performance not BS.
As to other odd ball valves such as you list, I would only keep for servicing purposes not new designs.
Please spell Japanese with upper case 'J'. It is a name. and GZ34 not gz. Lazy typing?
I vaguely remember you mentioning that you were at Luxman during that time frame but did not make the connection between you and the MB3045.. Now I know. I have a friend who has a bunch of them (none with 3045s in them unfortunately) and I have heard a pair of them in an earlier incarnation of my system.
guilty as charged, i am a lazy.....i am slow and i am old......not good traits i admit....
i recently repaired a Luxman LX-38, a 100v ac unit, and knowing the rarity of the output tubes, i converted
it to cathode resistor bias instead, so red plating is mitigated...
so unless the coupling cap gets leaky, it will never red plate....
the Futaba 6RHH2' are well liked in my Broskie ccda line amp running at just a b+ of 120 volts....i have access to about a hundred of these...
without giving away your trade secrets, i will appreciate if you can make a good enough description of your OPT's enough for me to get some clues as to make one.....
so far the only info that i can go by is that 1956 article by Alvin Lokchart ib his unity coupled OPT's...http://www.tubebooks.org/books/lockhart.pdf
and i believe you about topology and OPT's, this is the single most important part of any tube power amp, my mantra, get this OPT right and you will be rewarded with a great sounding amp....
i guess the downside with tubes is that transconductance is not as high as SS can go...
"So far the only info that i can go by is that 1956 article by Alvin Lokchart ib his unity coupled OPT's...http://www.tubebooks.org/books/lockhart.pdf"
I have seen this paper in recent times, But back in my day there was no internet that turns everyone into experts.
This is a good guide for you and starting point.
I spent years when I was young forming my own methods of transformer winding.
I get fed up with everyone chasing transconductance as the holy grail.
My 509 amp has a lot of feedback but not around the transformer and the input damping factor is in the 100:1 or so but the copper losses drop that to about 20 DF.
What is important is open loop response which in my case is 17 KHz. So that allows me full output at 60 KHz all day.
Most Transistor or Fet amps will not run at full power at 50 K all day long.
I consider 0.02% distortion at 80 watts good enough and less than 0.2% at 20 KHz at 80 watts.
Most classic valve amps have poor high frequency behaviour.
My old statement is electrons have no memory of where they have been. my other is I don't like recycled electrons.
What is this Futaba device?
I have seen this paper in recent times, But back in my day there was no internet that turns everyone into experts.
This is a good guide for you and starting point.
I spent years when I was young forming my own methods of transformer winding.
I get fed up with everyone chasing transconductance as the holy grail.
My 509 amp has a lot of feedback but not around the transformer and the input damping factor is in the 100:1 or so but the copper losses drop that to about 20 DF.
What is important is open loop response which in my case is 17 KHz. So that allows me full output at 60 KHz all day.
Most Transistor or Fet amps will not run at full power at 50 K all day long.
I consider 0.02% distortion at 80 watts good enough and less than 0.2% at 20 KHz at 80 watts.
Most classic valve amps have poor high frequency behaviour.
My old statement is electrons have no memory of where they have been. my other is I don't like recycled electrons.
What is this Futaba device?
Thank you for Futaba information. No data could I find and 6BQ7 looks kind of similar.
Mu and Gm are two factors. but I look at it this way for valves I work with voltage gains and for transistors I work with pure current gain. Both have different methods to achieve same result.
I knew Futaba back then for displays but was never aware of them making valves.
At Lux we used Toshiba NEC and some others and for phono or critical input imported Telefunken long plate 12AX7.
For one direct coupled amp the RCA 6336 power triode. NEC did make similar but not tough.
In Japanese this valve num 12AX7 was call ju-ni peke nana.
Mu and Gm are two factors. but I look at it this way for valves I work with voltage gains and for transistors I work with pure current gain. Both have different methods to achieve same result.
I knew Futaba back then for displays but was never aware of them making valves.
At Lux we used Toshiba NEC and some others and for phono or critical input imported Telefunken long plate 12AX7.
For one direct coupled amp the RCA 6336 power triode. NEC did make similar but not tough.
In Japanese this valve num 12AX7 was call ju-ni peke nana.
I think there's a typo, 170kHz, not 17kHz, yes? 60kHz closed loop is still great even by today's standard. I read somewhere your 509 output transformer was quad-filer wound, is that correct, if not, how was it wound, if you don't mind sharing.
can i ask you opinion of the NEC 12AX7's i have dozen of them came in yesterday....
the Futaba tunes might be oem'ed by either NEC or Toshiba or matshusita, these happens to american tube makers too...
triode....i did an amp based on triode mode, no gnfb, all open loop, and the owner is quite happy.....
topology is based on the Carver Silver Seven amps, though triode mode....
as i do not have test equipment set up, i can not give any specs...
An externally hosted image should be here but it was not working when we last tested it.
The schematic for the 3045 was published in Audio back in the day. I commend it to anyone for study, it is packed full of good tricks, many of which I've cheerfully stolen over the years.
One question I have about it- two of the primary windings (the ones in the cathode circuit of the output stage and the bootstrapped cathode follower) are tied together with 22u caps. Since they're quadrifilar wound (I presume!) and those points are equipotential, why did you find those caps necessary?
One question I have about it- two of the primary windings (the ones in the cathode circuit of the output stage and the bootstrapped cathode follower) are tied together with 22u caps. Since they're quadrifilar wound (I presume!) and those points are equipotential, why did you find those caps necessary?
Nice! I hope the guy has air-cond. in his flat, that little fan isn't going to cool the place down...
the guy in the picture was a house guest, he was fortunate to drop by
at the time i was testing that amp....
i remember that as sometime in December where ambients are no so severe....
So many stories and myths, I just laugh.
I will not say why there are those caps. Nothing to do with the drivers being able to drive speakers alone.
Now the Silver Sevens was Bob Carver jealous of my 500 watt 529 amp. but his was a crude driver circuit that has poor common mode rejection and is asymmetric in over load conditions.
That is why Bob Carver paid me for my modified driver circuit I designed for him in his current amps.
So many valve amps just copy the old circuits and they don't understand the dynamics and behaviour under various conditions.
I will not say why there are those caps. Nothing to do with the drivers being able to drive speakers alone.
Now the Silver Sevens was Bob Carver jealous of my 500 watt 529 amp. but his was a crude driver circuit that has poor common mode rejection and is asymmetric in over load conditions.
That is why Bob Carver paid me for my modified driver circuit I designed for him in his current amps.
So many valve amps just copy the old circuits and they don't understand the dynamics and behaviour under various conditions.
"can i ask you opinion of the NEC 12AX7's i have dozen of them came in yesterday"
They were about as typical as American 12AX7. None were ever as good as the old TFK long plate for quietness and microphony. Matsushita National were based on Philips Mullard construction and a notch down on average as far as noise and microphony.
Back in 1979 when I was buying bulk from Mullard about 90% were good for microphony and noise. However they all get cathode interface capacitance that increases flicker noise. so about 2,000 hours for noise.
The E283CC was specially designed for 10 K hours noise or cathode interface problems.
They were about as typical as American 12AX7. None were ever as good as the old TFK long plate for quietness and microphony. Matsushita National were based on Philips Mullard construction and a notch down on average as far as noise and microphony.
Back in 1979 when I was buying bulk from Mullard about 90% were good for microphony and noise. However they all get cathode interface capacitance that increases flicker noise. so about 2,000 hours for noise.
The E283CC was specially designed for 10 K hours noise or cathode interface problems.
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