Do you have any? The types with glass envelopes and wire pins aren't all that common. 6111 is mu=20, 6112 is mu=70. I have some used 6111s that I haven't fired up yet.
If you mean nuvistors, like 6CW4 mu=65, 7586 mu=35, I used to find these at hamfests before eBay, not so much any more. They are rather microphonic, ring at about 10kHz.
For low-level input, good 12AX7 or 12AY7 are by and large not microphonic, low flicker noise, well suited to phono input. Nuvistors are probably OK for line level but I'm wary of their microphony
If you mean nuvistors, like 6CW4 mu=65, 7586 mu=35, I used to find these at hamfests before eBay, not so much any more. They are rather microphonic, ring at about 10kHz.
For low-level input, good 12AX7 or 12AY7 are by and large not microphonic, low flicker noise, well suited to phono input. Nuvistors are probably OK for line level but I'm wary of their microphony
Hello ,
suminiature tubes ? Yes , look here :
and here is the complete projekt :
http://www.ak-tubes.de/Vorverstaerker/Pencil tube/pencil_tube_preamp.htm
and another little amp is here :
http://www.roehrentechnik.de/html/kolibri.html
Regards , Alex .
suminiature tubes ? Yes , look here :
and here is the complete projekt :
http://www.ak-tubes.de/Vorverstaerker/Pencil tube/pencil_tube_preamp.htm
and another little amp is here :
http://www.roehrentechnik.de/html/kolibri.html
Regards , Alex .
Hello Sy ,
it it very easy to remove this Tektronix terminals , they are only pressed in their plastic holders . You need only a screwdriver to pull them "carefully" out . I had no problems to do this .
@EC8010
Thank you for your nice comment for my little preamp , I had great fun , building this , but the pcb version is easier to build and works also very well .
Regards , Alex .
it it very easy to remove this Tektronix terminals , they are only pressed in their plastic holders . You need only a screwdriver to pull them "carefully" out . I had no problems to do this .
@EC8010
Thank you for your nice comment for my little preamp , I had great fun , building this , but the pcb version is easier to build and works also very well .
Regards , Alex .
Submini's work well. They are really not different than regular tubes, just smaller and cute looking 
Look at my web page using subminis in radios and in CD players as input tubes
Only ones I've seen as microphonic were filament DHT types. Indirectly heated subminis are designed to take a beating (like in rockets and warheads and such).
Well, not literally but they are designed for high G forces.
Look at my web page using subminis in radios and in CD players as input tubes
Only ones I've seen as microphonic were filament DHT types. Indirectly heated subminis are designed to take a beating (like in rockets and warheads and such).
Well, not literally but they are designed for high G forces.
SY,
I salvaged a bunch of those ceramic terminals from a Tek 545. I had the same question you do, and asked about it on some other forum (forgot which one). Someone replied that he'd threaded nuts onto the plastic posts and that they held the terminals nice and tight. You do know that you must use silver-bearing solder with these terminals to avoid lifting the metal “V” foils, right?
I salvaged a bunch of those ceramic terminals from a Tek 545. I had the same question you do, and asked about it on some other forum (forgot which one). Someone replied that he'd threaded nuts onto the plastic posts and that they held the terminals nice and tight. You do know that you must use silver-bearing solder with these terminals to avoid lifting the metal “V” foils, right?
> Only ones I've seen as microphonic were filament DHT types.
Mostly hearing-aid tubes. (Also widely used for spy-mikes and spy-radios, but the big market was hearing aids.) OK tubes, though note that this was the first market conquered by transistors, and the early dirty germanium transistors at that.
> Indirectly heated subminis are designed to take a beating (like in rockets and warheads and such). Well, not literally...
Yes, literally. Many of these indirect-heat subminis were intended for controllers, telemetry, timers, and proximity sensors in missiles, from the early Titan monster to little Nikes. Threatening the USSR was real good business through the 1950s (and beyond; but sand-state took up the fight). The more powerful rockets could boost a little harder than standard mini construction could take reliably; also weight was a killer issue, while life-hours were so low and maintenance funds so big that sockets were not needed. Solder it in, 99% will live well over 1,000 hours but will actually run less than one hour before BOOM. If one does go dead before launch, replace the whole module.
Obviously they don't survive the warhead explosion; by then their evil work would be done.
Since octals and minis with clamps survived use in railroads, 1942 Plymouths, and guitar amps, I don't see that the G-force rating is any use for normal people. However a missle controller must give a steady signal even if the rocket motor has bubbles and burps or hits air turbulence, so they may have better internal bracing (less microphonics) than everyday tubes.
Other than the packaging, all the indirect-heat subminis that I've glanced at are clearly based on common conventional tube types easily found in mini (and at higher heat ratings). I doubt they will blind-test any different than good-quality conventional tubes.
Mostly hearing-aid tubes. (Also widely used for spy-mikes and spy-radios, but the big market was hearing aids.) OK tubes, though note that this was the first market conquered by transistors, and the early dirty germanium transistors at that.
> Indirectly heated subminis are designed to take a beating (like in rockets and warheads and such). Well, not literally...
Yes, literally. Many of these indirect-heat subminis were intended for controllers, telemetry, timers, and proximity sensors in missiles, from the early Titan monster to little Nikes. Threatening the USSR was real good business through the 1950s (and beyond; but sand-state took up the fight). The more powerful rockets could boost a little harder than standard mini construction could take reliably; also weight was a killer issue, while life-hours were so low and maintenance funds so big that sockets were not needed. Solder it in, 99% will live well over 1,000 hours but will actually run less than one hour before BOOM. If one does go dead before launch, replace the whole module.
Obviously they don't survive the warhead explosion; by then their evil work would be done.
Since octals and minis with clamps survived use in railroads, 1942 Plymouths, and guitar amps, I don't see that the G-force rating is any use for normal people. However a missle controller must give a steady signal even if the rocket motor has bubbles and burps or hits air turbulence, so they may have better internal bracing (less microphonics) than everyday tubes.
Other than the packaging, all the indirect-heat subminis that I've glanced at are clearly based on common conventional tube types easily found in mini (and at higher heat ratings). I doubt they will blind-test any different than good-quality conventional tubes.
These guys have a tubefilter to be used like a zapfilter as analog filter stage. Unfortunately there is no further info available.
http://www.audioxtension.com/rev/sd2500/sd2500.htm
http://www.audioxtension.com/rev/sd2500/sd2500.htm
Hello,
it sounding like all selfmade amps very good
But not so clean as an SE. Because the magnetisation in the OPT uses all 4 quadrants you will have more k3 distortion, the good sounding k2 is reduced. An SE would produce more good sounding k2 and the OPT is working only in the 1st quadrant, this makes also more k2.
this subminis don´t have real grids, there are only some wires . This makes this tubes noise, but not so much. You only can hear this with ears directly at the speakers. This is not an High End amplifier, but good enough to listen music with...
Gerd
it sounding like all selfmade amps
very goodBut not so clean as an SE. Because the magnetisation in the OPT uses all 4 quadrants you will have more k3 distortion, the good sounding k2 is reduced. An SE would produce more good sounding k2 and the OPT is working only in the 1st quadrant, this makes also more k2.
this subminis don´t have real grids, there are only some wires . This makes this tubes noise, but not so much. You only can hear this with ears directly at the speakers. This is not an High End amplifier, but good enough to listen music with...
Gerd
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