Anyone got a partial list of tubes to avoid? We all know that 300B and that junk is good stuff, what about the bad?
Just curious...
Tim
Just curious...
Tim
I could never get a 6360 to remain stable
I built a series of RF transmitters and amplifiers with the 6360 -- for 6m, 2m RF -- worked great until you came near it and would go into oscillation all by itself.
this would be an interesting question to pose to the rec.radio.amateur.homebrew or rec.radio.amateur.boatanchor newsgroup.
I built a series of RF transmitters and amplifiers with the 6360 -- for 6m, 2m RF -- worked great until you came near it and would go into oscillation all by itself.
this would be an interesting question to pose to the rec.radio.amateur.homebrew or rec.radio.amateur.boatanchor newsgroup.
ECC82. I realize that I will be shouted at for this, but despite being very consistent between manufacturers/samples, it really does produce far more distortion than a 6SN7.
PD500 is a terrible valve for low-noise stages...
PD500 is a terrible valve for low-noise stages...
AVOID...
Hi,
This could turn out to be a fun thread...are there any limitations set upfront?
O.K., as far as small signal triodes go the computor tubes usually suck big time in the microphony department.
Just a sample though,😉
Hi,
This could turn out to be a fun thread...are there any limitations set upfront?
O.K., as far as small signal triodes go the computor tubes usually suck big time in the microphony department.
Just a sample though,😉
Most tubes used in TVs are pretty worthless (ie you couldn't give them away), although some of them can be used quite well in audio circuits.
I would say the most useless tubes would be the high voltage half wave rectifiers like 866A. These are mercury vapour filled and can be used if you are very keen, but for most intents and purposes are not any use to the audio DIYer..
I would say the most useless tubes would be the high voltage half wave rectifiers like 866A. These are mercury vapour filled and can be used if you are very keen, but for most intents and purposes are not any use to the audio DIYer..
Don't knock the TV valves!
Even given your caveat, this seems an unwarranted bias. Some of the TV valves are really rather good, EL821 makes a lovely CCS. "P" valves seem a nuisance if you are used to 6.3V heaters, but they're much cheaper, and they were at the tail end of bulk valve production, when quality control was paramount.
I've just thought of another one to avoid. PC900. It looks excellent on paper, but when you come to measure it, the gm is nothing like as exciting.
(Edit: I think I've misinterpreted your wording, and we actually agree.)
ShiFtY said:
Even given your caveat, this seems an unwarranted bias. Some of the TV valves are really rather good, EL821 makes a lovely CCS. "P" valves seem a nuisance if you are used to 6.3V heaters, but they're much cheaper, and they were at the tail end of bulk valve production, when quality control was paramount.
I've just thought of another one to avoid. PC900. It looks excellent on paper, but when you come to measure it, the gm is nothing like as exciting.
(Edit: I think I've misinterpreted your wording, and we actually agree.)
There's some TV tubes that are useful. I've seen a stereo voltage-variable volume control based on a 6HS8.
BTW I have a Tele diamond-base flat plate 12AX7 computor tube, does that mean it's a). gold, b). pure sheet, or c). average? 😱
Tim
BTW I have a Tele diamond-base flat plate 12AX7 computor tube, does that mean it's a). gold, b). pure sheet, or c). average? 😱
Tim
Don't discount tv tubes. Compactrons can be very useful and have great sound quality. A compactron is many tube sections in one big honkin' envelope.
Frankly, I'd stay away from 300b's and the like. They are not a good value. Sure they can sound good, but you pay top dollar for them.
The same can be said of the 6DJ8, it's a great tube, but the high transconductance comes from close element spacing. This means that the typical manufaturing tolerances make for large part to part variations. and different manufacturers 6dj8's behave differently. I still like the tube and still use it, but the audiophool branded ones command a high price.
Each tube type has a purpose, there are no "bad" ones per-say, just bad implimentations of the wrong types.
Sheldon
Frankly, I'd stay away from 300b's and the like. They are not a good value. Sure they can sound good, but you pay top dollar for them.
The same can be said of the 6DJ8, it's a great tube, but the high transconductance comes from close element spacing. This means that the typical manufaturing tolerances make for large part to part variations. and different manufacturers 6dj8's behave differently. I still like the tube and still use it, but the audiophool branded ones command a high price.
Each tube type has a purpose, there are no "bad" ones per-say, just bad implimentations of the wrong types.
Sheldon
Hmm... yes I phrased that terribly, what I meant was that TV tubes are not valuable, and you can always find boxes and boxes of them, as opposed to NOS 300B, EL34, etc. They sell for virtually nothing in comparison.
As people have said, they can be used to great effect, and are far from useless.
Sorry for the miscommunication! 😀
As people have said, they can be used to great effect, and are far from useless.
Sorry for the miscommunication! 😀
Stay away of:
1.Voltage amplifier tubes:ECC 81-82-83.Avoid especially the 83 in RIAA peramps,as this tube rolls off sharply after 31 KHz.
The above mentioned tubes impart a somehow "muffled" and sleepy sound,compared with the cheapest 6SN7 or 6SL7 series.
I say,let them for Jolida and Jadis fans....
However,I heard some E802CC and E801CC pieces that played quite acceptable.Their price is,though,rather high and these tubes are pretty difficult to find.
2.Output triodes:300B Cetron.This is the worst-sounding 300B I ever heard,and it has a very bad reliability.
As for the TV tubes,I agree that some of them can play unexpectedly well;what's missing in most of the cases is a clever schematic and some keen tweaking.
1.Voltage amplifier tubes:ECC 81-82-83.Avoid especially the 83 in RIAA peramps,as this tube rolls off sharply after 31 KHz.
The above mentioned tubes impart a somehow "muffled" and sleepy sound,compared with the cheapest 6SN7 or 6SL7 series.
I say,let them for Jolida and Jadis fans....
However,I heard some E802CC and E801CC pieces that played quite acceptable.Their price is,though,rather high and these tubes are pretty difficult to find.
2.Output triodes:300B Cetron.This is the worst-sounding 300B I ever heard,and it has a very bad reliability.
As for the TV tubes,I agree that some of them can play unexpectedly well;what's missing in most of the cases is a clever schematic and some keen tweaking.
Oh,I forgot....
Rectifiers to be avoided:
EZ40,EZ41,EZ80,EZ81 of any brand
6X4 of any brand
Awful!
Rectifiers to be avoided:
EZ40,EZ41,EZ80,EZ81 of any brand
6X4 of any brand
Awful!
Le Basseur said:Stay away of:
1.Voltage amplifier tubes:ECC 81-82-83.Avoid especially the 83 in RIAA peramps,as this tube rolls off sharply after 31 KHz.
The above mentioned tubes impart a somehow "muffled" and sleepy sound,compared with the cheapest 6SN7 or 6SL7 series.
I say,let them for Jolida and Jadis fans....
However,I heard some E802CC and E801CC pieces that played quite acceptable.Their price is,though,rather high and these tubes are pretty difficult to find.
2.Output triodes:300B Cetron.This is the worst-sounding 300B I ever heard,and it has a very bad reliability.
As for the TV tubes,I agree that some of them can play unexpectedly well;what's missing in most of the cases is a clever schematic and some keen tweaking.
Damned ! I surely know now why my Mc C22 do sounds so bad
BTW, With a E83cc I can reach 80Khz/-4dB...maybe a clever shematic 🙂
Fly
My shop "ears" currently go out to 100 Mhz. But the crappy ones stuck to the sides of my pie-hole seem to be pretty low bandwidth and really are only good to 18KHz or so. I want a refund.
The only real tubes to avoid are chinese power tubes (or they were to be avoided). A friend had fire shoot out of his Citation II because of chinese KT88's.
Sheldon
The only real tubes to avoid are chinese power tubes (or they were to be avoided). A friend had fire shoot out of his Citation II because of chinese KT88's.
Sheldon
Dud triodes
There is a number of triodes which, because of their low prices and relatively high gm may appear to be quite attractive.
A particular example I have in ind is EC97. This is a variable-mu triode and as such is really most unsuited for audio applications.
All that glisters etc.
7N7
There is a number of triodes which, because of their low prices and relatively high gm may appear to be quite attractive.
A particular example I have in ind is EC97. This is a variable-mu triode and as such is really most unsuited for audio applications.
All that glisters etc.
7N7
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