Just thinking out loud....
Ive seen good stuff written about this little Russian D.H. Tube wired as triode...
I'm wondering how it would be to use as a gain-stage rather than driver/O/P stage, maybe with MOSFET on top....
Any thoughts....?😉
Ive seen good stuff written about this little Russian D.H. Tube wired as triode...
I'm wondering how it would be to use as a gain-stage rather than driver/O/P stage, maybe with MOSFET on top....
Any thoughts....?😉
I'm thinking along the same lines. A grounded cathode stage has pretty high output impedance, though. One might have to add a cathode follower or similar to be able to drive interconnect cables.
~Tom
~Tom
I've never used this tube but I can supply a quote from someone who has regarding microphonics:
"Mark's tube dampening (solder coil+silicon) - first reports - I tried this technique - somewhat different. Instead of silicon (fear of corrosion) I used liquid urethane spray (for PCB masking). It claims to resist hot solder, and is definitely neutral (good for protecting polished copper). First applied a solder coil, then 3-4 coats of urethane. The tubes were soviet 4P1L DH pentodes driving my 6B4G PP amp. They have a long, 1-1.5 microphonic resonance, sometimes very audible on piano passages. Tubes run very hot (as hot as a typical EL84). So far no problems with urethane layer or the tube itself. With the coil, the sonic signature changed. The 1kHz ringing is very well muffled down. But there's ANOTHER resonance, somewhere in 200-300Hz area. Not the original bug shifted downwards - this is something completely new, although nowhere as loud, and decays quickly. It's not a problem with piano, - sometimes it interferes with male vocals. But still - definitely worth trying. With the 2-tube driver, I found the less fatuguing option to have 1 stage dampened, second untreated, - just marginally better than both stages dampened. BTW, the coil need not be too big - in my case, covering 1/3 of available glass (one layer) was as effective as covering the whole length"
"Mark's tube dampening (solder coil+silicon) - first reports - I tried this technique - somewhat different. Instead of silicon (fear of corrosion) I used liquid urethane spray (for PCB masking). It claims to resist hot solder, and is definitely neutral (good for protecting polished copper). First applied a solder coil, then 3-4 coats of urethane. The tubes were soviet 4P1L DH pentodes driving my 6B4G PP amp. They have a long, 1-1.5 microphonic resonance, sometimes very audible on piano passages. Tubes run very hot (as hot as a typical EL84). So far no problems with urethane layer or the tube itself. With the coil, the sonic signature changed. The 1kHz ringing is very well muffled down. But there's ANOTHER resonance, somewhere in 200-300Hz area. Not the original bug shifted downwards - this is something completely new, although nowhere as loud, and decays quickly. It's not a problem with piano, - sometimes it interferes with male vocals. But still - definitely worth trying. With the 2-tube driver, I found the less fatuguing option to have 1 stage dampened, second untreated, - just marginally better than both stages dampened. BTW, the coil need not be too big - in my case, covering 1/3 of available glass (one layer) was as effective as covering the whole length"
I had an experience with 4P1L tubes. They are very nice tubes for drivers and output stages when triode connected, better than 2A3. They are easy to parallel for more power. About 1.5K output resistance and great linearity without any feedback. But for an input stage I would use some smaller tube, like 6J4P, 6J5P, 6J9P in triode mode.
What would you like to do with it ? Line stage ?
I have some experience as PP-UL output stage. I just built a 15 W amplifier with two 4P1L and Hammond 1608 (no the best OPT, I know).
It performed very well.
I have some experience as PP-UL output stage. I just built a 15 W amplifier with two 4P1L and Hammond 1608 (no the best OPT, I know).
It performed very well.
i have a bunch of these tubes, dhp's, http://frank.pocnet.net/sheets/127/3/3Q5GT.pdf
i was contemplating a line stage input choke loaded into a 5687 cathode folowers....
As 3q5gt seems to be the same as 3s4, you can easily do a sort of "quickie" clone, a battery-operation tube preamp.
Take a look here for a good scheme (register to the forum before!): DIY Audio Projects Forum • New Bottlehead Quickie battery tube preamplifier kit
Ciao!
Hi guys! Just reviving this thread with some information I need to share about the 3Q5. After many hours of experimentation and trials, it is NOT a 3S4. If you look carefully at the sheets, you'll find this to be true too. That said, with a Quickie circuit, I couldn't get it to behave anything like a 3S4. I tried with and without the CCS, pentode operated, you name it. Pulled my hair out over it. Bottom line, I did create a proper circuit for the 3Q5 as a pentode with 80v on the plate and a blue LED as bias at around 3.6v. That preamp is fabulous. But, for those of you thinking you can swap it into your quickies or build another quickie based on the 3Q5gt, feel free to try, but I'm confident you'll find it just won't work. Keep rocking!
Hello.
Maybe it will be useful to someone.
Piotr
* 3Q5gtT LTSpice model 0.09ma
.subckt 3Q5gtT P G K
Bp P K I=(0.05036453274m)*uramp(V(P,K)*ln(1.0+(0.2209619176)+exp((9.521741071)+(9.521741071)*((7.360139478)+(-30.80040466m)*V(G,K))*V(G,K)/sqrt((16.48516043)**2+(V(P,K)-(5.285332637))**2)))/(9.521741071))**(1.377322565)
Cgp G P 2.5p
Cgk G K 6.0p
Cpk P K 11.4p
Rpk P K 1G
d3 G K dx1
.model dx1 d(is=1n rs=2k cjo=1pf N=1.5 tt=1n)
.ends 3Q5gtT
Maybe it will be useful to someone.
Piotr
* 3Q5gtT LTSpice model 0.09ma
.subckt 3Q5gtT P G K
Bp P K I=(0.05036453274m)*uramp(V(P,K)*ln(1.0+(0.2209619176)+exp((9.521741071)+(9.521741071)*((7.360139478)+(-30.80040466m)*V(G,K))*V(G,K)/sqrt((16.48516043)**2+(V(P,K)-(5.285332637))**2)))/(9.521741071))**(1.377322565)
Cgp G P 2.5p
Cgk G K 6.0p
Cpk P K 11.4p
Rpk P K 1G
d3 G K dx1
.model dx1 d(is=1n rs=2k cjo=1pf N=1.5 tt=1n)
.ends 3Q5gtT
Attachments
Hello.
Well then one more DHT tube.
Piotr
* 3D6T LTSpice model 0.13ma
.subckt 3D6T P G K
Bp P K I=(0.08022678989m)*uramp(V(P,K)*ln(1.0+(-0.08003982834)+exp((7.564066834)+(7.564066834)*((9.721264885)+(17.72047963m)*V(G,K))*V(G,K)/sqrt((19.82125426)**2+(V(P,K)-(-3.429339352))**2)))/(7.564066834))**(1.316832316)
Cgp G P 2.5p
Cgk G K 6.0p
Cpk P K 11.4p
Rpk P K 1G
d3 G K dx1
.model dx1 d(is=1n rs=2k cjo=1pf N=1.5 tt=1n)
.ends 3D6T
Well then one more DHT tube.
Piotr
* 3D6T LTSpice model 0.13ma
.subckt 3D6T P G K
Bp P K I=(0.08022678989m)*uramp(V(P,K)*ln(1.0+(-0.08003982834)+exp((7.564066834)+(7.564066834)*((9.721264885)+(17.72047963m)*V(G,K))*V(G,K)/sqrt((19.82125426)**2+(V(P,K)-(-3.429339352))**2)))/(7.564066834))**(1.316832316)
Cgp G P 2.5p
Cgk G K 6.0p
Cpk P K 11.4p
Rpk P K 1G
d3 G K dx1
.model dx1 d(is=1n rs=2k cjo=1pf N=1.5 tt=1n)
.ends 3D6T
Attachments
The 3D6 wired as a pentode is a directly heated driver I'm rather fond of. They absolutely require filament balancing resistors if you heat them with 3V though.