Heya Douglas. I did lots of experiments with my 12B4s using Pimm BBMCCS and DN2450's, singly and in cascode, choke loaded, differential with OPT's as chokes, parafeed etc and in the end came back to R loaded diff with a CCS in the tail as being best to my ears in my system as it stood at the time. That's the beauty of this stuff; so many different flavours.
Frank,
you can have a look at a Tronal 12B4A.How does it look like? 🙂
Brett,
a schem is always acceptable! 😀
Or some more details.Like what kind of CCS or what kind of PSU.
Are you using DC to filaments?
you can have a look at a Tronal 12B4A.How does it look like? 🙂
Brett,
a schem is always acceptable! 😀
Or some more details.Like what kind of CCS or what kind of PSU.
Are you using DC to filaments?
Hi,
Can't make much of it really.
Normally, actually almost always, US made tubes have an acid etched marking on the tube stating the type of tube.
From the way this is done you can often tell with good certainty who the manufacturer was.
In the case of the Tronal tubes you show here, I can't see any dead giveaway as to their origine other than that they look European made by the way the plate is fixed to the mica holders.
This is surprising as I don't know if this tube was ever made in Europe.
Maybe, just maybe, this could be made by Ei in former Yugoslavia.
They're about the only European based manufacturer to have made some typically American tubes such as the 12BH7A, 6FQ7 for example.
Sorry to be of such little help here, 😉
Can't make much of it really.
Normally, actually almost always, US made tubes have an acid etched marking on the tube stating the type of tube.
From the way this is done you can often tell with good certainty who the manufacturer was.
In the case of the Tronal tubes you show here, I can't see any dead giveaway as to their origine other than that they look European made by the way the plate is fixed to the mica holders.
This is surprising as I don't know if this tube was ever made in Europe.
Maybe, just maybe, this could be made by Ei in former Yugoslavia.
They're about the only European based manufacturer to have made some typically American tubes such as the 12BH7A, 6FQ7 for example.
Sorry to be of such little help here, 😉
Ei and 12B4
Frank,
afaik Ei was never making 12B4.My opinion is based only on catalogues and lists of tubes from the factory I have collected ten years back.Majority of TV tubes they produced had european markings(PCC,PCF,PCL...). But,sincerely I can not be 100% sure!
On the other hand you are completely right about 12BH7A and 6CG7!And I think they are still in production.
Regards,
Yugovitz
fdegrove said:
Frank,
afaik Ei was never making 12B4.My opinion is based only on catalogues and lists of tubes from the factory I have collected ten years back.Majority of TV tubes they produced had european markings(PCC,PCF,PCL...). But,sincerely I can not be 100% sure!
On the other hand you are completely right about 12BH7A and 6CG7!And I think they are still in production.
Regards,
Yugovitz
Hi,
Quite probably so....
Guess we will just have to see if Resident can find some acid etched clues on the glass.
BTW, the resemblance with the 6AS7G is quite striking...
I can't help but adore the way the wings (radiators for heat convection) are placed at both sides of the heater making for a lovely glow when the tube is in service....
A mini, single 6AS7G, triode with a useful mu and reasonable Ri.
One could make a miniature Liliput amp with those quite easily....Yummie. 🙂
Cheers, 😉
Quite probably so....
Guess we will just have to see if Resident can find some acid etched clues on the glass.
BTW, the resemblance with the 6AS7G is quite striking...
I can't help but adore the way the wings (radiators for heat convection) are placed at both sides of the heater making for a lovely glow when the tube is in service....
A mini, single 6AS7G, triode with a useful mu and reasonable Ri.
One could make a miniature Liliput amp with those quite easily....Yummie. 🙂
Cheers, 😉
I'm checking right now the tube that I had scanned (pic above) but I can't see nothing.
I'll check the other three that I own when I'll go back to my small lab. 🙂
Sorry but I can’t find anything!
What if I’ll use a voltage doubler at 6,3V, that I already have, filter that and feed a 317 or 7806 to end up with 6V?
Hey-hey!!!,
Let's try and stay away from cap-input filters. Get a 22-0-22 vac @ 1.5 amps, use two diodes in full wave( Schottkey please ) and L-C filter the raw supply. A 6R/300 mHy Hammond will be fine to deliver 600 mA to the two 12B4's @ 12.6 V. Feed the regulator from this supply.
Or L-C-R-C and avoid the regulator completely...perhaps use more like 19-0-19 for the input voltage.
regards,
Douglas
Let's try and stay away from cap-input filters. Get a 22-0-22 vac @ 1.5 amps, use two diodes in full wave( Schottkey please ) and L-C filter the raw supply. A 6R/300 mHy Hammond will be fine to deliver 600 mA to the two 12B4's @ 12.6 V. Feed the regulator from this supply.
Or L-C-R-C and avoid the regulator completely...perhaps use more like 19-0-19 for the input voltage.
regards,
Douglas
thanks Douglas for the tip.
But I'll need a separate transformer and a choke!
There's no any space at the chassis I already have. 🙁
I'm trying to find a simpler solution. Any idea?
But I'll need a separate transformer and a choke!
There's no any space at the chassis I already have. 🙁
I'm trying to find a simpler solution. Any idea?
12b4a
😀 😀 😀
Do you have microphonic problems with your Dumont 12b4? I am currently using GE, and there is slight microphonics. Havent tried any other variant.
skyraider said:
Haven't tried them yet. Got them with some other tubes for a future project.
Sheldon
I found the problem wasn't microphonics but that 12b4s test all over the place - wide differences. I use them in PPP in one of my amps with a 6SL7 diff pair+CCS input and 6.6K OPT. Mind - I prefer the sound of PPP 6S4A in another amp, which in this case has a 6N1P input and a different 8K OPT. Not much is said about the 6S4A, though it seems it was the precursor to the 12b4. Anyone else used both of them and can comment - I'd be very interested. One rather neat fact is that 2 of 6S4A drop in for one EL84 - twice 22mA for one 45mA, but heater for both is 1.2A instead of .75A. I have PPP 6S4A in my Leak Stereo 20 and it sounds very nice indeed. Andy
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