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#1
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Posted to rec.audio.tubes
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Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current.
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#2
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On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote:
Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. Peter Wieck Melrose Park, PA |
#3
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On Tuesday, July 9, 2019 at 5:23:18 AM UTC-7, Peter Wieck wrote:
On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote: Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. Peter Wieck Melrose Park, PA |
#4
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Posted to rec.audio.tubes
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On Tuesday, July 9, 2019 at 5:23:18 AM UTC-7, Peter Wieck wrote:
On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote: Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. Peter Wieck Melrose Park, PA |
#5
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Posted to rec.audio.tubes
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On Monday, July 15, 2019 at 6:15:16 PM UTC-7, buffstereo wrote:
On Tuesday, July 9, 2019 at 5:23:18 AM UTC-7, Peter Wieck wrote: On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote: Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. Peter Wieck Melrose Park, PA Sorry for my inept response to Peter Wieck as regards 171A triodes. (Repeated attempts, 20 years since I've posted). I'm on the stereo side of the fence cousin, but if only a 171A will save your sweet radio, I'm sure I can find and give it to you for free. Only one, and nobody else, but I get the honest angst of a tube gear lover, so contact me and I'll try to help out. Good luck with your music! Robert Thompson On Monday, July 15, 2019 at 6:15:16 PM UTC-7, buffstereo wrote: On Tuesday, July 9, 2019 at 5:23:18 AM UTC-7, Peter Wieck wrote: On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote: Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. Peter Wieck Melrose Park, PA |
#6
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Robert, thank you for the offer!
I keep enough 71As for my needs into the foreseeable future, and I keep several in reserve for other collectors as may be needed. I straddle the fence between Audio and Radio, and so I am acutely sensitive to the mis-adaptation of vintage tubes. I am a member of the DVHRC, and we have our twice-yearly Kutztown Radio Shows in May and September. If you are nearby, please join us. There is a strong leavening of Audio, and increasing, with each show. http://www.dvhrc.com/docs/Upcomingshowinfo.pdf I run the repair clinic at the Club table. Peter Wieck Melrose Park, PA |
#7
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Posted to rec.audio.tubes
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On 2019-07-15 18:15, buffstereo wrote: On Tuesday, July 9, 2019 at
5:23:18 AM UTC-7, Peter Wieck wrote: On Tuesday, July 9, 2019 at 2:05:49 AM UTC-4, Paul James wrote: Does anyone here have any experience with using 171a in a linestage. Thinking of using constant current. The 71A is a low-gain DHT that is valued and prized by the Vintage Radio community. You in the Audio Community have multiple options for this purpose that do not suck resources from your cousin. Who have, too often, no viable alternatives. interesting Well the antique radio crowd has often had to re-wind transformers and do other things to restore an old radio to "original" as much as possible. So here's a thought: what if it were possible to actually RE-BUILD one of those old tubes? It would require all of the right stuff, vacuum gear, glass blowing equipment, and some way to make all of the various electrode components according to the original spec. You might even need 'exotic metals', dangerous chemicals, nitrogen purges to get rid of O2 and H2O vapor, and so on. There was once a popularity of picture tube re-building "kits", ones I've heard about online anyway, where you'd get a set of popular electron guns to put into 'dud' tubes. I suppose they could also be re-phosphored somehow, not sure how well THAT would work. But the skills and equipment to do that sort of thing isn't all that available any more, and I'm sure there are *RIDICULOUS* "environmental" stupid-laws that get in the way of doing that sort of thing on a commercial basis. Quite frankly, you could NEVER get zoning for that sort of thing inside of a city. This is probably why most tubes are now made in eastern Europe [where they even use leaded gasoline still, from what I've heard], and in Ruswia, and in China, and other places where they seem to NOT have a problem with polluting everything around them. [I wouldn't want to pollute everything, just design the systems carefully so that the hazardous material can be properly disposed of, and NOT "ban it outright" in a knee-jerk overreaction as is the case all too often, especially in places like Cali-Fornicate-You] In any case, I've seen stuff online about home-made tubes. To do these right you need the original specs and drawings so you can replicate the parts and the distances properly. Then you'd have to be able to curve trace them [to verify the specs match] and somehow recycle the fallouts so you aren't tossing a lot of valuable (possibly rare, possibly expensive) materials. and it would be VERY labor intensive, unless there's some kind of robotic manufacturing process that could do customized tube re-making. So things I think would be needed that could re-use components: a) replacement heaters b) cathode re-coating c) insulator disk replacement d) socket replacement [probably have to because of the glass seals around the pins, you'd have to re-do all of this probably] e) 'getter material' and that silvery spot that consists of sodium or some other oxygen scavenging metal Other than that, if the grids aren't damaged, and the cathode needs re-coating but is otherwise ok, then a replacement filament plus re-coat cathode and the tube should be like new again. Well, after getting the vacuum and getter stuff right, anyway. [there'dd be no money in it, and it'd have to be a kind of "labor of love" hobby by people who want to preserve antique radios and tube electronics in general] My $.10 worth |
#8
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For most "popular" vintage radio tubes (Valves), there are solid-state replacements. And a small amplifying triode such as the 71A is a trivial exercise along those lines.
Put in a glass device for appearance. Put in a solid-state device for operation. Refurbishing a globe tube - not so much. Peter Wieck Melrose Park, PA |
#9
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On 2019-07-22 12:21, Peter Wieck wrote:
For most "popular" vintage radio tubes (Valves), there are solid-state replacements. And a small amplifying triode such as the 71A is a trivial exercise along those lines. Put in a glass device for appearance. Put in a solid-state device for operation. Refurbishing a globe tube - not so much. Peter Wieck Melrose Park, PA yeah I wouldn't want to refurbish a tube amp with solid state replacements, though. New designs, maybe. Some MOSFET devices would work very well in that kind of application, hundreds of volts Vds etc.. JFET seems possible also but not sure if the parts would be as easily available. Most of the time I deal with MOSFETs for switching, like voltage control from a microcontroller, so it's alwaysw enhancement types, not too concerned about linearity. Depletion MOSFETS with linear operating ranges are 'out there' but not sure how they're being used in non-RF linear applications these days. Probably a lot available in online parts selectors. -- (aka 'Bombastic Bob' in case you wondered) 'Feeling with my fingers, and thinking with my brain' - me 'your story is so touching, but it sounds just like a lie' "Straighten up and fly right" |
#10
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On 2019-07-22 12:21, Peter Wieck wrote:
Refurbishing a globe tube - not so much. at some point in time, may be no other alternative... I'd just be curious if anyone's willing to do that. |
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