A friend of mine has a Sansui stereo tube amplifier with 6R-A8 outputs? This amplifier is great sounding, but we can't seem to locate output tubes for it. Anyone here seen these? Know where they can be purchased?
Here is the best listing i've found
http://w1.871.telia.com/~u87149905/hexodup/6ar8.htm
and the data sheet pdf.
$7 each at the TubeStore.
dave
http://w1.871.telia.com/~u87149905/hexodup/6ar8.htm
and the data sheet pdf.
$7 each at the TubeStore.
dave
Hi,
Afraid that's not the same tube, Dave...
The Japanese had a number of their own references and that Sansui tube is one of them...
Same trouble with some Luxman gear amongst others.
Cheers,😉
Afraid that's not the same tube, Dave...
The Japanese had a number of their own references and that Sansui tube is one of them...
Same trouble with some Luxman gear amongst others.
Cheers,😉
fdegrove said:
That's gotta be confusing, having different tubes with the same designation 🙁
dave
Hi,
Tell me about it...To make it even worse almost none of these were exported except when inside the gear that is...
Pretty depressing but it had something to do with post WWII regulations, I think.
What sets the two types apart is that hyphen as far a nomenclature is concerned.
Too bad,😉
Tell me about it...To make it even worse almost none of these were exported except when inside the gear that is...
Pretty depressing but it had something to do with post WWII regulations, I think.
What sets the two types apart is that hyphen as far a nomenclature is concerned.
Too bad,😉
Made a mistake for sending incomplete message
Made a mistake and sent the incomplete massage.
Sorry.
Hello everyone.
NEC 6R-A8 is an indirectly heated Triode 9pin mT tube (just like a EL84/6QB5).
Please note that this tube was designed by NEC (Nippon Electric Co.) and made "only" by NEC (no other tube manufacturers made this tube, Toshiba had the 6G-A4 that rivals 6R-A8 tube).
And this tube was originated from 6BK5, and the NEC modified it.
As a result, you can see that this tube has a screen grid internally connected to plate.
The characteristics of this tube are kind of a famous 2A3 with higher input sensitivity (i.e. similar plate resistance, higher gm, higher mu).
Now, this tube is a very �grare item�h even in Japan.
I usually don�ft see it in catalog listing of almost any tube broker in Japan.
Even when I see it (once a year or so), the price is unbelievably high.
I know that NEC made this tube at least somewhere around 1980s (I remember I bought this tube when I was a kid).
So I don�ft think there was any export problems for this tube.
Lux used this tube for the Type 38 integrated Amp (they changed to 50A-C10 on later models) and used for their �gKit�h amps.
These tubes popped-out when Japanese Tube makers stopped making 2A3, and have greater input sensitivity but unfortunately the linearity is not as good as the 2A3 (well most high gm tube have this tendency).
And since this tube was not so expensive, the material and construction is just as a normal tube in spite of having plate dissipation of 15 watts (and 6 watts for heater).
So you have to be careful to not overload this tube (it is a mT tube!) .
It does not use carbonized nickel plate or fancy glass envelope like the Bendix Red Bank tubes
Since it is almost impossible to obtain these tubes, and if the tube fails, the only way to salvage the amp is to modify it accept more popular tubes, but this is not easy.
Here is the Spec for this tube (may be useful).
Pin1 IC, Pin2 K, Pin3 G, Pin 4-5 H, Pin 6 G, pin 7-8 IC, Pin 9 P. (must leave IC open!, both grid pins must be connected for heat dissipation)
Max ratings
Eb=350V , Pp=15W, Ik=120mA, Ec1=-100Vmax, Rg=0.1(Fixed) 0.25Mohms(Self)
Heater 6.3V 1.0 A
Gm=10.5 (mA/V) rp=0.9Kohm, u=9.7
(Self Bias P-P) Eb=270V, Rk=260 ohms(for 2 tubes) RL=5K (p-p), eg1(g-g rms)30V
Ib=80 to 120 mA (2 tubes) Po=12Watts , KF=3%
Regards,
jun
Made a mistake and sent the incomplete massage.
Sorry.
Hello everyone.
NEC 6R-A8 is an indirectly heated Triode 9pin mT tube (just like a EL84/6QB5).
Please note that this tube was designed by NEC (Nippon Electric Co.) and made "only" by NEC (no other tube manufacturers made this tube, Toshiba had the 6G-A4 that rivals 6R-A8 tube).
And this tube was originated from 6BK5, and the NEC modified it.
As a result, you can see that this tube has a screen grid internally connected to plate.
The characteristics of this tube are kind of a famous 2A3 with higher input sensitivity (i.e. similar plate resistance, higher gm, higher mu).
Now, this tube is a very �grare item�h even in Japan.
I usually don�ft see it in catalog listing of almost any tube broker in Japan.
Even when I see it (once a year or so), the price is unbelievably high.
I know that NEC made this tube at least somewhere around 1980s (I remember I bought this tube when I was a kid).
So I don�ft think there was any export problems for this tube.
Lux used this tube for the Type 38 integrated Amp (they changed to 50A-C10 on later models) and used for their �gKit�h amps.
These tubes popped-out when Japanese Tube makers stopped making 2A3, and have greater input sensitivity but unfortunately the linearity is not as good as the 2A3 (well most high gm tube have this tendency).
And since this tube was not so expensive, the material and construction is just as a normal tube in spite of having plate dissipation of 15 watts (and 6 watts for heater).
So you have to be careful to not overload this tube (it is a mT tube!) .
It does not use carbonized nickel plate or fancy glass envelope like the Bendix Red Bank tubes
Since it is almost impossible to obtain these tubes, and if the tube fails, the only way to salvage the amp is to modify it accept more popular tubes, but this is not easy.
Here is the Spec for this tube (may be useful).
Pin1 IC, Pin2 K, Pin3 G, Pin 4-5 H, Pin 6 G, pin 7-8 IC, Pin 9 P. (must leave IC open!, both grid pins must be connected for heat dissipation)
Max ratings
Eb=350V , Pp=15W, Ik=120mA, Ec1=-100Vmax, Rg=0.1(Fixed) 0.25Mohms(Self)
Heater 6.3V 1.0 A
Gm=10.5 (mA/V) rp=0.9Kohm, u=9.7
(Self Bias P-P) Eb=270V, Rk=260 ohms(for 2 tubes) RL=5K (p-p), eg1(g-g rms)30V
Ib=80 to 120 mA (2 tubes) Po=12Watts , KF=3%
Regards,
jun
Hi Jun,
I am using Luxkit A1020 with 4 of Nec 6a-r8 but I tried many time to buy another 6ar8 tube for my reserve.
Unfortunately if my tube is going to die what will I can do with the rest OPT ....remaining thing in my amplifier
What tube can I replace 6ar8 in the future or how can I modify it with Lux OY 14 OPT
Thanks in advance
Rgds,
Huy
I am using Luxkit A1020 with 4 of Nec 6a-r8 but I tried many time to buy another 6ar8 tube for my reserve.
Unfortunately if my tube is going to die what will I can do with the rest OPT ....remaining thing in my amplifier
What tube can I replace 6ar8 in the future or how can I modify it with Lux OY 14 OPT
Thanks in advance
Rgds,
Huy
This valve was indeed used by a LuxKit amp. The valve is a sort of triode wired EL84.
So with a couple of pin reasignments just wire an EL84 or a 6CH6 up as triode.
The 6C-A10 was a much bigger valve and was used in the original 38FD amps.
Any help I can offer you are welcome. Tim de P.
So with a couple of pin reasignments just wire an EL84 or a 6CH6 up as triode.
The 6C-A10 was a much bigger valve and was used in the original 38FD amps.
Any help I can offer you are welcome. Tim de P.
I have not read every thread going as it would be impossible,
I stumbled on this however,
never mind.
I stumbled on this however,
never mind.
Just that Matsushita was part owned by Philips. Much of their TV etc in the 60s were very much Philips derived. Some of their valves they used the hyphen as part of the number difretiator . 6C-A10 50C-A10 50B-H26 etc.
They also made the usual 12AX7 etc under the National Brand.
Toshiba and NEC tended to follow the American designs.
I designed jointly with NEC the 3045 valve used in the MB3045 amp at Lux.
They also made the usual 12AX7 etc under the National Brand.
Toshiba and NEC tended to follow the American designs.
I designed jointly with NEC the 3045 valve used in the MB3045 amp at Lux.
I always wondered who was behind the 3045.. Interesting tube, did you contribute to the MB3045 design as well? (Which is one of the few commercial PP amps I really like)
I designed the whole circuit back in '75. Transformers as well.
I don't contribute to this forum much anymore, as everyone appears to know so much more than me. To many experts so it seems.
I don't contribute to this forum much anymore, as everyone appears to know so much more than me. To many experts so it seems.
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....
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...
Thick skin and a good eye for conceit are useful assets in venues like this. I was apparently too busy making a living in video circuit design during the golden age of tube audio DIY, so I will personally appreciate any commentary that you're willing to contribute. Please carry on.