New 6V6 Bootstrapped CF.
It has been awhile since I have had time to do more than lurk in the forum. Came across some 6V6G's a while back and decide it was high time to sling some solder.
This is the test bed for the preamp. Still missing is the volume, a selector knobs. I am also waiting on the MJE5731 for the SSHV(1) regulator.
B+will be 330V @ 25-30mA fed by the SSHV regulator running at 60-65mA. The cathode load will be various from different styles of CCS's to a good old resistor. Right now I have CCS's galore from a previous project I was doing so they went in. The filament will either be the universal reg or LM317 setup in CCS mode.
The power supply is seperate and sports a single PT 5UG4 rectifier splitting into parallel 20H inductor and res caps of 100uF. All motor run caps. The raw filtered B+ will be 365V.
It has been awhile since I have had time to do more than lurk in the forum. Came across some 6V6G's a while back and decide it was high time to sling some solder.
This is the test bed for the preamp. Still missing is the volume, a selector knobs. I am also waiting on the MJE5731 for the SSHV(1) regulator.
B+will be 330V @ 25-30mA fed by the SSHV regulator running at 60-65mA. The cathode load will be various from different styles of CCS's to a good old resistor. Right now I have CCS's galore from a previous project I was doing so they went in. The filament will either be the universal reg or LM317 setup in CCS mode.
The power supply is seperate and sports a single PT 5UG4 rectifier splitting into parallel 20H inductor and res caps of 100uF. All motor run caps. The raw filtered B+ will be 365V.
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6V6 Update
In a matter of minutes my 124b preamp was removed from the room. The 6V6 CF with raw DC feed (380V) and AC heaters biased at 25mA by far beats the 124b. Waiting on the 400V transistors and need time to design the SSHV2 circuit board. So I still have some work to do including building a dedicated measurement PC to document this thing. Until then will just be kicking back and listening.
The clarity, and depth of the soundstage is fantastic. Excuse the dust on the Opus's. Will have to clean them tomorrow. The have performed flawlessly for almost two years now. Every day.
In a matter of minutes my 124b preamp was removed from the room. The 6V6 CF with raw DC feed (380V) and AC heaters biased at 25mA by far beats the 124b. Waiting on the 400V transistors and need time to design the SSHV2 circuit board. So I still have some work to do including building a dedicated measurement PC to document this thing. Until then will just be kicking back and listening.
The clarity, and depth of the soundstage is fantastic. Excuse the dust on the Opus's. Will have to clean them tomorrow. The have performed flawlessly for almost two years now. Every day.
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Well, a friend says he wants a great line stage. He has given me cash to play with. I bought two reds 5692's but weeks have passed and I haven't started yet.
I want something different, I have read this thread and I think I'm going for it. It troubles me the microphonics problem though. How should I build the chassis? I was planning a wooden base with a top metal plate. I can choose the thickness of the metal plate, the base will be made by some carpenter. If anyone can offer me some good tips to avoid problems I'd appreciate it.
EDIT
I don't understand this.
I want something different, I have read this thread and I think I'm going for it. It troubles me the microphonics problem though. How should I build the chassis? I was planning a wooden base with a top metal plate. I can choose the thickness of the metal plate, the base will be made by some carpenter. If anyone can offer me some good tips to avoid problems I'd appreciate it.
EDIT
I don't understand this.
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I'm interested too (suspend or soft rubber decouple the tubes on a small sub chassis, it pays off.) for my future #26 line preamp and Valve Itch phono, could you post a pic Salas?
You can do it like in a turntable. Place the tubes on a small metal base and decouple this metal base from the undercase using rubber grommets. 🙂
Isolation Grommets
This is what I do. For the test rig I just used a piece of pcboard. In final version will be aluminum, copper, or steel. Not sure yet.
I have no noise pick-up that is discernable. I can tap the tubes and hear a ring but not as bad as my 12b4 pre was.
This is what I do. For the test rig I just used a piece of pcboard. In final version will be aluminum, copper, or steel. Not sure yet.
I have no noise pick-up that is discernable. I can tap the tubes and hear a ring but not as bad as my 12b4 pre was.
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Both will work. The blue washers are actually isolation grommets made for the purpose. Pretty cheap from grainger. The tubes are pretty well isolated. Have to hit the chassis pretty hard to get it to sound through the speakers.
Sgregory I like your chassis (knobs too).
Salas isn't leaking any info out on the sub chassis. Top secret?
Salas isn't leaking any info out on the sub chassis. Top secret?
What secret? From early in the thread I recommend some form of isolation. The less microphonic on steady chassis with the gain circuit was the new Tungsol from those I checked. In CF things are easier, and Scott's combination of CF and grommets won't create trouble with any make, even the most sensitive ST bottle ones.
I have nylon spacers and screws, can I use this black rubber ring (it's M3)?
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They look very small and stiff.... try to get some soft rubber (like the one used in the SME3009 base plate fixing screw orings)... very soft.
rubber grommets
mount tubes in a just big enough alu or copper plate
use rubber grommets in its chassis mounting holes
and in your main chassis, use grommets as well
mount a small piece of soft neoprene between plates, on mounting screw
use selflocking nut
mount your trafos with anti vibration rubbers too
screws should be very carefully 'adjusted'
it really makes a big difference on how much buzzing is transferred to the chassis
with a simple wooden stick(or stetoscope) you can easily hear how much
mount tubes in a just big enough alu or copper plate
use rubber grommets in its chassis mounting holes
and in your main chassis, use grommets as well
mount a small piece of soft neoprene between plates, on mounting screw
use selflocking nut
mount your trafos with anti vibration rubbers too
screws should be very carefully 'adjusted'
it really makes a big difference on how much buzzing is transferred to the chassis
with a simple wooden stick(or stetoscope) you can easily hear how much