Is it possible that power supply impedance has something to do with microphonics of 12B4A?
Those of your experiencing bad microphonics from 12B4A, were you using passive PSU or regulated? Maida, shunt reg, or other?
Maybe there is a correlation, maybe there is not. Would be interesting to find out...
Those of your experiencing bad microphonics from 12B4A, were you using passive PSU or regulated? Maida, shunt reg, or other?
Maybe there is a correlation, maybe there is not. Would be interesting to find out...
It was a fully passive CLCLC PSU.
CCS has even 60dB PSRR, largely immune to the "input" voltage variation, so doesn't require "super" regulation.
BTW my daily used (gyrator loaded 801) preamp PSU is such simple CLCLC.
https://www.diyaudio.com/community/threads/801a-tube-preamp.395883/
CCS has even 60dB PSRR, largely immune to the "input" voltage variation, so doesn't require "super" regulation.
BTW my daily used (gyrator loaded 801) preamp PSU is such simple CLCLC.
https://www.diyaudio.com/community/threads/801a-tube-preamp.395883/
B+ I use CRC + SSHV2 + CCS.
Heaters/Filaments I use Salas BiB 12.6V
Two separate R-Core tx for B+ & filaments.
BTW Ale Moglia said not necessary SSHV2 using his Hybrid Mu-Follower but SQ it's a lot better using SSHV2 and not only with DHT also with IDHT....
Heaters/Filaments I use Salas BiB 12.6V
Two separate R-Core tx for B+ & filaments.
BTW Ale Moglia said not necessary SSHV2 using his Hybrid Mu-Follower but SQ it's a lot better using SSHV2 and not only with DHT also with IDHT....
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I had more issues with tube noise with DHT that the 12B4. Once I got a good stable circuit I have no noise.
i just built 6C41C line preamp, very good triode
https://www.claudiomas.fr/ux201-dht-preamp/
https://www.claudiomas.fr/ux201-dht-preamp/
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Would a 6B4G or 6C4C really be an overkill? With CCS and about the same Ua(90-125) and Ia (20-25mA) as the 12B4 it looks reasonably linear. But maybe they are microphonic as hell?
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6C4C /126B/6C45Pe 1:1 10K input transformer line preamp, classic line stage, my reference
https://www.claudiomas.fr/6c4c-6c45pe-preamp/
https://www.claudiomas.fr/6c4c-6c45pe-preamp/
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I can gently tap my 12B4A with a pencil and get no audible speaker output.
New GE for the most part. Have tried a number of different tubes over the years.
New GE for the most part. Have tried a number of different tubes over the years.
Great! Checked the curves, with loadline CCS and 20k load. At 120V and 25mA it looks quite nice. Rod´s filament bias(Rk ca 9 ohm?) must be perfect for this circuit.
For those who have not seen it... Here is a commercial 12B4A linestage.
https://www.audioresurgence.com/2021/06/emotive-audio-epifania-preamp-review.html
https://www.audioresurgence.com/2021/06/emotive-audio-epifania-preamp-review.html
What's the output impedance using CCS for 12B4?
Or better how can calculate the output impedance for different cascode CCS for different tubes?
TIA
Felipe
Or better how can calculate the output impedance for different cascode CCS for different tubes?
TIA
Felipe
Why not the 6P43P-E in triode mode? mu of ~7, Rp of about 1000 ohms, it's got curves that trade blows with the best DHT, and is dirt cheap. They sound fantastic too- very linear, clear, and transparent. Rivals a 45 or 4P1L at lower plate resistance. Build the Salas 6V6 line stage with a pair and I bet you will be very happy. As soon as I get my shop back together I will finish the PCB design and be actually finishing up a pre using a pair for myself.
