resident said:Ok I’m going CFB!
Thanks BHD for the courage!
My new approach is attached!
I’m planning to use Va=480V and Ia=70-75mA.
If my maths are correct I need about 150Vp-p at each grid!!! to have about 30W .
Wayne’s driver doesn’t suits to drive this.But I’m thinking to change the first 6SN7 to 6SL7.The gain with 6SN7 is about 40dB.With the 6SL7 and without changing the values of the components,the gain increases to 55dB.Too much headroom!!!!
Have my thoughts any sense?????
Try to go Williamson style driver. The direct coupled long tailed driver has limited voltage swing, due the high DC voltage on the splitter's grid. The Williamson has separated driver stage which use the full power supply voltage, and can gives enough voltage to drive.
sajti
I have done some changes in the output schem.I’ll drive the pair of 6L6 at 300-320V/ 50-55mA. At 450V (as it is in my schem) the idle current will be too small so the operating point will be in a region of the increased distortion.
I’m planning to drive them at pure class A!
With these changes the drive voltage for each 6L6 grid will be about 90Vp-p.So I can use my driver stage as it is.The only change I’d like to do is to put the one half of the first 6SN7 as a CCS at the tail of the phase splitter.The idea became when I thought that I don’t like to use one half for one channel and the other half for the other.
These tubes don’t have internal screen!!
And of course, I don’t want to go from 3 stages to 4!
I found some Russian 6SN7 labeled as 6H8C without brand.
Under 6H8C ,on the glass ,is written 8507 and on the base “OTK”.Buy them???
I’m planning to drive them at pure class A!
With these changes the drive voltage for each 6L6 grid will be about 90Vp-p.So I can use my driver stage as it is.The only change I’d like to do is to put the one half of the first 6SN7 as a CCS at the tail of the phase splitter.The idea became when I thought that I don’t like to use one half for one channel and the other half for the other.
These tubes don’t have internal screen!!
And of course, I don’t want to go from 3 stages to 4!
I found some Russian 6SN7 labeled as 6H8C without brand.
Under 6H8C ,on the glass ,is written 8507 and on the base “OTK”.Buy them???
Hi,
8507 is just a datecode. They're NOS.
OTK is a gouvernmental agencies "tested and approved" stamp.
The Russkie 6SN7 is fine if you let it run in for a while but opininion differs on whether it really is a direct replacement for the US 6SN7s.
If you're willing to spend some time on finding its "sweet spot" then go for it I'd say.
Cheers,
8507 is just a datecode. They're NOS.
OTK is a gouvernmental agencies "tested and approved" stamp.
The Russkie 6SN7 is fine if you let it run in for a while but opininion differs on whether it really is a direct replacement for the US 6SN7s.
If you're willing to spend some time on finding its "sweet spot" then go for it I'd say.
Cheers,
@fdegrove
I bought 8 of them!!
I'm going back to my design,now.
About the PSU.I'm thinking not to use chokes or too complex designs.
And I'm planning to use one PSU for both channels.
Don't ask why.Just to keep the project at low prices.If I like the sound of it I'll go to two monoblocks with 6550 CFB P-P.
I like shindo style.
Bridge ( I have some 08HFA60 diodes!!) and CRCRCRC....
BUT how many CRs??
And values of R and C?Which are the ideal ones?
I'm doing some simulation with PSUDII but I like to have some suggestions on this.
Heeeelp!
I bought 8 of them!!
I'm going back to my design,now.
About the PSU.I'm thinking not to use chokes or too complex designs.
And I'm planning to use one PSU for both channels.
Don't ask why.Just to keep the project at low prices.If I like the sound of it I'll go to two monoblocks with 6550 CFB P-P.
I like shindo style.
Bridge ( I have some 08HFA60 diodes!!) and CRCRCRC....
BUT how many CRs??
And values of R and C?Which are the ideal ones?
I'm doing some simulation with PSUDII but I like to have some suggestions on this.
Heeeelp!
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