Greetings all
happy new year etc..
I am quite interested in getting 12B4 linestage either complete or have one built. I have looked and seen a few schematics of the web but not sure what to go for. So just looking for some guidance really or maybe one for sale.
Audio_D
happy new year etc..
I am quite interested in getting 12B4 linestage either complete or have one built. I have looked and seen a few schematics of the web but not sure what to go for. So just looking for some guidance really or maybe one for sale.
Audio_D
Why a 12B4? And why not build it yourself? Also, all 12B4s available will likely be old stock, I don't think new ones are being made. So a mainstream manufacturer probably wouldn't likely commit to one with a finite supply of tubes available.
S.
S.
Hi
thanks for the advice, yes I think building one would be the way to go could you recommend a circuit with a good power supply?
thanks for the advice, yes I think building one would be the way to go could you recommend a circuit with a good power supply?
A few years back Broskie offered an Aikido kit that used 12B4s, I think. I don't think it's available now but if you troll back through his blogs you'll find some info on it. BTW, a stereo Aikido using 12B4s would require EIGHT tubes. Why not a line stage using four ECC88s? Unless you are trying to drive an amp with a low input impedance the ECC88s would work fine.
S.
Battle of the Cheap Line Stages – Part 1 | Wall of Sound | Audio and Music Reviews
Tube CAD Journal
S.
Battle of the Cheap Line Stages – Part 1 | Wall of Sound | Audio and Music Reviews
Tube CAD Journal
This is what I use. 4 channels of 12b4 as shown and 2 channels with a quality opamp driver to subwoofer. First two channels are amorphous, 3 and 4 are non-amorphous. That way I can play around with which one sounds best on the woofer vs tweeter.
No microphonics or noise of any kind, super quiet.
The 50k terminals are where a stepped attenuator goes for volume control.
No microphonics or noise of any kind, super quiet.
The 50k terminals are where a stepped attenuator goes for volume control.
My version (FWIW) of a 12B4 line stage is very similar to stenak's. I use CCS, not resistive, loading to accommodate the awkward 10 Kohm IHF "standard" load. The heater CT gets biased off B+ for noise control and that voltage divider is not shown.
CCS loading is good for PSRR. So, simply bridge rectifying the O/P of a Triad N-68X isolation transformer and CLC (Π section) filtering rates to be quite adequate.
CCS loading is good for PSRR. So, simply bridge rectifying the O/P of a Triad N-68X isolation transformer and CLC (Π section) filtering rates to be quite adequate.
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Good evening, tbh I wanted the try a 12b4 because I have never heard one but have read good things.. so why not try it out. plus the simplicity is also an attraction. Thanks for posting those circuits there both look interesting and should not cost the earth with a decent solid state power supply.
I'm not a fan of the 12B4. I had a bunch of used ones and they measured all over the place. I think they were computer tubes. I didn't think they sounded special in any way.
What exactly do you want a line stage to do? What are the inputs and what's it going to drive? I'd be surprised if there aren't better choices which are also simple enough.
What exactly do you want a line stage to do? What are the inputs and what's it going to drive? I'd be surprised if there aren't better choices which are also simple enough.
I agree Im sure could be better sounding valves but ill never know unless i have a 12B4 pre built then take it from there.
Fully agree with Audio_D. Many many moons ago I learned how to build a tube pre and I did it with 5687. It was OK from power up without any trouble may be because it was simple build. Otherwise.........
Dear Audio_D, go ahead and build it if you don't like the sound we will help you to convert it, even, for a DHT pre.
Regards
Dear Audio_D, go ahead and build it if you don't like the sound we will help you to convert it, even, for a DHT pre.
Regards
This is mine, and boards are one the way
Tube buffer for driving stuff.
I tested that circuit before and it gave crazy low output impedance, if you just want a pair of boards for fun, i got 10 on the way from the Chinese FR4 farmer.
Tube buffer for driving stuff.
I tested that circuit before and it gave crazy low output impedance, if you just want a pair of boards for fun, i got 10 on the way from the Chinese FR4 farmer.