Hi,
Anyone hear about McAlisteraudio.com? He's a one man band who builds his own tube amps using horizontal TV tubes, and he actually winds his own transformers. Totally hand built units. He believes design and implementation are much more important than expensive audiophile components. I was so impressed with his design, cost, and enthusiastic recommendations from owners that I ordered one for my self, the PP150 which is a push-pull 75watt/ch amp at under $1000. The only bad thing is you have to wait several weeks because he takes his time building these things. Note the pictures on his site are old, the new models look much better aesthetically.
I'm no technical guru, so I like to hear more about what you DIYers think about his design and implementation. Any one of you used the horizontal TV tubes in this application? Any manufacturers out there that does this also?
Anyone hear about McAlisteraudio.com? He's a one man band who builds his own tube amps using horizontal TV tubes, and he actually winds his own transformers. Totally hand built units. He believes design and implementation are much more important than expensive audiophile components. I was so impressed with his design, cost, and enthusiastic recommendations from owners that I ordered one for my self, the PP150 which is a push-pull 75watt/ch amp at under $1000. The only bad thing is you have to wait several weeks because he takes his time building these things. Note the pictures on his site are old, the new models look much better aesthetically.
I'm no technical guru, so I like to hear more about what you DIYers think about his design and implementation. Any one of you used the horizontal TV tubes in this application? Any manufacturers out there that does this also?
Horizontal output tubes have been used in audio by home builders and big time audio companies alike (McIntosh MC3500). The EL509, EL519and similar big horizontal output tubes are used is some OTL amps. I like the 6LW6 for its sheer power capabilities. I believe it to be the biggest most powerfull of the octal sweep tubes. A pair can crank out 150 watts in push pull. The 6AV5 is a much smaller, older tube that was successfully rewired as a triode and sold as a 6B4 by Sylvania and Philips. It does sound quite good in this application.
Sweep tubes rock! 😀
I like vertical sweep triodes for small amps. They are inherently insanely linear and can be quite efficient.
Got a sweep pentode that isn't particularily linear? Triode mode it! Great example is the EL36, which sounds real icky in pentode, even g2 driven. Triode it and you nearly have a 2A3 set of curves, only with more (5 watts) out.
I like vertical sweep triodes for small amps. They are inherently insanely linear and can be quite efficient.
Got a sweep pentode that isn't particularily linear? Triode mode it! Great example is the EL36, which sounds real icky in pentode, even g2 driven. Triode it and you nearly have a 2A3 set of curves, only with more (5 watts) out.
Check my 6CD6GA thread. Maybe one of these days I'll finish the amp so I can find out how it sounds.... All joking aside, I'll be done in a couple of weeks. I'm curious about the ultimate output capability of the tube in screen driven single-ended mode, and how it will sound with cheap iron like the Hammond 125ESE.
I sold 2 pair of Frazier theater amps on ebay last summer. They used 6gt5a 's as outputs. Great amps.
MGH said:
I quite like his design and implementation. Then, again, it looks like his design philosophy is nearly identical to my own. Like McAlister, I favor direct coupling as much as possible, and I believe in fixed bias over auto bias, and stiff drivers for finals. I am, however, not so feedback-o-phobic as he appears to be.
TV tubes rawk! Since CRT deflection requires precision amplification, vertical and horizontal power amps are excellently linear. The horizontal deflection PAs work quite well with unconventional topologies such as screen drive and "ultra-triode". I have a design in the works that uses 6BQ6GTBs in an ultra-triode. Picked off a loadline giving 4.9W @ 0.3% THD (est). I expect these to sound very good indeed.
Sweep tubes
I love them. I have a pair of McIntosh MI350s (The pro version of the MC3500) on which I did a full ground up restoration with lots of modifications.
I have listened to many amps which use 6550, KT88, EL34 etc and they do not compare to sweep tubes.
Of course the trick is the output transformer.
I love them. I have a pair of McIntosh MI350s (The pro version of the MC3500) on which I did a full ground up restoration with lots of modifications.
I have listened to many amps which use 6550, KT88, EL34 etc and they do not compare to sweep tubes.
Of course the trick is the output transformer.
Re: Re: Horizontal TV tubes used in amplifier?
Hi Miles,
I'm interested. Got a 1/2 box full of those. Schema?
Do you perchanse have triode curves? I couldn't find any 🙁
Hi Miles,
Miles Prower said:
I'm interested. Got a 1/2 box full of those. Schema?
Do you perchanse have triode curves? I couldn't find any 🙁
Hello Moer,
Could you please expand on the output transformer?
Best regards, Arjen.
Of course the trick is the output transformer.
Could you please expand on the output transformer?
Best regards, Arjen.
Of course the trick is the output transformer.
You won't find useful curves for screen drive of horizontal deflection tubes, except for the Svetlana EL509 sorta clone. I had to generate my own for the 6CD6GA. Expect pretty linear-looking curves, but with high plate resistance and also requiring either high B+ or positive screen drive to get substantial plate current.
You won't find useful curves for screen drive of horizontal deflection tubes, except for the Svetlana EL509 sorta clone. I had to generate my own for the 6CD6GA. Expect pretty linear-looking curves, but with high plate resistance and also requiring either high B+ or positive screen drive to get substantial plate current. Unless you are dedicated to living dangerously, the screen voltage ratings of most horizontal deflection tubes are not high enough to get anything useful using the standard triode strapping schemes.
wrenchone said:
Surprisingly, for many sweep tubes, you can find curves for Vg1=0 and varying Vg2. See, for example, the GE datasheet for the 6JN6, a popular sweep tube used in the Berning amps. It's worth thumbing through some tube manuals.
Wow! I didn't know sweep tubes are popular among DIYers, and few manufacturers. Why aren't these tubes more popular in main stream high end audio?
Fashion, for one. And, in all fairness, availability at production scale- NOS is not a good way to go in commercial designs. That's an advantage that amateurs have. My sweep tube amps use 6LF6- no way could I sell them to anyone in good conscience, much less source a thousand of those tubes.
Hi,
1. So you don´t consider these three sheets for EL36/6CM5, PL36/25E5 at various prebias conditions at my site not to be useful?
Look here
2. Forget about those published Svetlana EL509 screen driven curves. If you don´t trust my word, just try to reproduce them. I guarantee for
especially at lowish plate voltages.
3. With 2., I didn´t say screen driven EL509 is a Bad Thing. I just said: Don´t trust the published curves.
Tom
wrenchone said:
1. So you don´t consider these three sheets for EL36/6CM5, PL36/25E5 at various prebias conditions at my site not to be useful?
Look here2. Forget about those published Svetlana EL509 screen driven curves. If you don´t trust my word, just try to reproduce them. I guarantee for
especially at lowish plate voltages.3. With 2., I didn´t say screen driven EL509 is a Bad Thing. I just said: Don´t trust the published curves.
Tom
Re: Re: Re: Horizontal TV tubes used in amplifier?
Hi Gregg,
regarding trioded 6BQ6 plate curves:
I know quite a reliable way to get such curves plotted for you. You should know, too 😉
Tom
Hi Gregg,
regarding trioded 6BQ6 plate curves:
I know quite a reliable way to get such curves plotted for you. You should know, too 😉
Tom
Certain sweep tubes were used in ham radio and illegal CB amplifiers in the 1970's and early 80's. I remember seeing a Phantom 500 (yes 500 watts at 27 MHz) that used 10 6LQ6's. These amplifiers ate tubes faster than a guitar player that always turns it up all the way. GE even made a 6LQ6 with a 12 volt filament for mobile amplifiers, the 8950. By the mid 80's the worlds supply of some sweep tubes was drying up and the cost had skyrocketed. Some of these amplifiers are still in use today and the tubes that fit them are expensive. Many amplifiers were modified to use whatever tubes were available, thus reducing the supply of most large sweep tubes.
I began collecting 6LW6's, 26LW6's, and 36LW6's about 10 years ago when I figured out how much power I could get from them. They were going for about $5 each on Ebay. I have seen them go for over $30 each recently, although I just got 2 for under $10 each. An 8950 can sell for over $50 each. The price and supply issue will keep most commercial manufacturers from using sweep tubes.
Another reason that scares many people away from sweep tubes is the low screen voltage rating. This requires a seperate regulated screen supply in pentode mode, and precludes triode or UL mode in most cases. The hypersensitive screen grid is also what allows screen drive. Screen drive does not work well on most common audio pentodes.
Hi TubeLab,
Well, first of all there is no need for screen drive at all with "audio" pentodes. They do just fine for their intended purpose using simple, normal g1 drive 😉
Screen drive is just a horrible crutch to hopefully get acceptable results from "non-audio" pentodes - for a very high price, indeed, because I think most dudes underestimate the capabilities of a driver being needed to do it right.
As a matter of fact, your MOSFET driver approach is The Right Way, since using a big cheap video pentode together with a real big tube driver certainly is more expensive than using a conventional audio power pentode plus a conventional tub driver.
Not to talk of additional PSU requirements (separate heater, maybe stacked B+) when using a tube as a driver for a screen driven power tube.
Tom
Well, first of all there is no need for screen drive at all with "audio" pentodes. They do just fine for their intended purpose using simple, normal g1 drive 😉
Screen drive is just a horrible crutch to hopefully get acceptable results from "non-audio" pentodes - for a very high price, indeed, because I think most dudes underestimate the capabilities of a driver being needed to do it right.
As a matter of fact, your MOSFET driver approach is The Right Way, since using a big cheap video pentode together with a real big tube driver certainly is more expensive than using a conventional audio power pentode plus a conventional tub driver.
Not to talk of additional PSU requirements (separate heater, maybe stacked B+) when using a tube as a driver for a screen driven power tube.
Tom
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