yep is good ,but is yours the rigth ones ?
gap for 50ma ?
as impedence speakers is low you unload a bit the tube ,have you the rigth bias ?
The bias is fine, the transformer is for 300B according to Lundahl, the speakers are fine, I don't understand the questions
Nothing fancy - some old Chinese ones and some decent condition EH ones. I stick to the cheap end of the 300b offerings.
Present arrangement is EL33 driver and a 1:2 step-up transformer on the input. I like a higher current driver and the EL33 sounds good to me, but mu is only around 20. Plenty of other higher current choices at about mu=20, such as ECC99, KT61 or EL84 in triode etc.
I'm sure you're right! Most people agree with you about the C3m. I've never got round to it. A bit expensive these days, but they are still around used. I started going through some pentodes in triode and also double triodes like the 6N1P and never came across any I liked the sound of, but it was a fairly small sample. When I tried a bunch of higher current tubes with a mu around 20 I started getting sounds I liked - KT61, EL84 and EL33 in triode sounded good to me. So I added a 1:2 step-up and that's where I am right now.
That's an interesting idea. I did try the 6e6P as a driver and I didn't like it enough, so I went on to other things. I have a few 6e6P.
Whither Loftin-White, Full Monkey?
Hi,
This thread is on Page 39 and there are some words that I have not seen.
They are:
*Loftin-White*, and
*Full Monkey*
Anyone here familiar with these words? Anyone here build either of these amplifiers with 45, 2A3 or 300B output tubes?
I've done 24A/45/James JS-6123-HS Loftin-White, and EL84/2A3/MQ FS-030 Loftin-White. Both have been successful...2A3 is playing at the moment.
I plan a C3g(triode)/300B/Something 5, 6, 7K Full Monkey in the forseeable future. Martin Seddon (of OZ) posted one of these on the JoeList back in 2016, using an operating point of 350 Va-k, 50 mA Ia, and 5K OT for one of the low(est) distortion points on the 300B data sheet operating points Table. N.B.: lower distortion OPs can be found in the plots, with variance from those values.
Curious, Anyone?
Best,
RC
Hi,
This thread is on Page 39 and there are some words that I have not seen.
They are:
*Loftin-White*, and
*Full Monkey*
Anyone here familiar with these words? Anyone here build either of these amplifiers with 45, 2A3 or 300B output tubes?
I've done 24A/45/James JS-6123-HS Loftin-White, and EL84/2A3/MQ FS-030 Loftin-White. Both have been successful...2A3 is playing at the moment.
I plan a C3g(triode)/300B/Something 5, 6, 7K Full Monkey in the forseeable future. Martin Seddon (of OZ) posted one of these on the JoeList back in 2016, using an operating point of 350 Va-k, 50 mA Ia, and 5K OT for one of the low(est) distortion points on the 300B data sheet operating points Table. N.B.: lower distortion OPs can be found in the plots, with variance from those values.
Curious, Anyone?
Best,
RC
6P15 indeed. C3m in triode is indeed 19 - I've been mixing this up with C3g at mu=40. I think high current triodes or pseudo triodes with a mu of around 20 are a really good bunch of tubes.
C3M and C3G are highly specialized tubes from Deutsche Bundespost. They have a special sound signature and are prone for microphonics.
Even very delicate in handling, never even move a warm tube. The heater can broke anytime and your tube will be lost. I don't use those special tubes anymore.
"The heater can broke anytime and your tube will be lost. I don't use those special tubes anymore."
It's your decision (BTW ANY heaters can broke anytime).
This type of tubes (metal can shielding) cools down very slowly, so if you moving/shaking it before the metal cup quite cools, may be ruined.
This tubes working flawlessly for some years at 7/24 as communication cable repeaters, so it's manufacturing quality impeccable as much as possible: 1.5 thousandths failure for each 1000 hours.
Many design use these tubes (for example Yamamoto A-09), because of it's parameters (swinging capability, distortion spectrum, "tone").
I also satisfied using these (mainly C3g, but own several bunch of C3m so - it's mesh anode structure is outstandingly constructed - tubes.
It's your decision (BTW ANY heaters can broke anytime).
This type of tubes (metal can shielding) cools down very slowly, so if you moving/shaking it before the metal cup quite cools, may be ruined.
This tubes working flawlessly for some years at 7/24 as communication cable repeaters, so it's manufacturing quality impeccable as much as possible: 1.5 thousandths failure for each 1000 hours.
Many design use these tubes (for example Yamamoto A-09), because of it's parameters (swinging capability, distortion spectrum, "tone").
I also satisfied using these (mainly C3g, but own several bunch of C3m so - it's mesh anode structure is outstandingly constructed - tubes.
Hi Andy,
Care to elaborate on your impressions of the 6e6p and how you used it? (Sorry if you covered this earlier, already.)
I am thinking of trying the 6e5p transformer coupled to a 300B. Thus my interest. D3a and C3g are very expensive these days.
Regards,
John
I really can't remember - I didn't pay much attention. I just remember that I was disappointed with the sound and didn't wish to pursue it. Disappointing for me means it isn't close to the DHTs I usually use. I do use indirectly heated tubes at times when I can find any that are closer in sound to DHTs - good timbre to instruments, clarity, musicality. These are generally older pre-WW2 tubes with larger bases rather than later 9 pin tubes.
Obviously, you haven't made the experienc with broken heaters at this tube.
I have- and I've made the experience with other tubes not.
That means, those heaters are far less prone to break than the C- Deutsche Post tube heater.
And the tube looks good, but is VERY sensible to microphonics.
With its unusual heater voltage of 20V, its more sensible to hum on heaters, too.
All those design flaws have let me forgot about using this tube in my amps, because there are literally thousands of types that have those problems not.