SEWA driver
Miket,
Looks fine in theory. My comments from building a number of tranformer out 6C45pi stages are:
Heater supply being indirectly heated doesn't need all the complexity.
Rather than the choke and parafeed, it would be better with a good conventional transformer.
But I recognise these days much is fear and fashion!
Miket,
Looks fine in theory. My comments from building a number of tranformer out 6C45pi stages are:
Heater supply being indirectly heated doesn't need all the complexity.
Rather than the choke and parafeed, it would be better with a good conventional transformer.
But I recognise these days much is fear and fashion!
SEWA driver
Oh I forgot,
Please fix bias the 6C45, a battery is good. That cathode bypass cap is certain death to any good sound!
Oh I forgot,
Please fix bias the 6C45, a battery is good. That cathode bypass cap is certain death to any good sound!
Possible alternatives
hifryer,
It is an easy step to use 2-1.5V batteries in series with the cathode instead of the resisiors / capacitors on the cathode.
THe Edcor XSM2.4K/600 transformer is rated at 50mA current on the primary. You can remove the inductor and cap and the primary can actually be used between the plate and B+. I have drawn it the way you suggest and can try both to see which one I like best.
hifryer,
It is an easy step to use 2-1.5V batteries in series with the cathode instead of the resisiors / capacitors on the cathode.
THe Edcor XSM2.4K/600 transformer is rated at 50mA current on the primary. You can remove the inductor and cap and the primary can actually be used between the plate and B+. I have drawn it the way you suggest and can try both to see which one I like best.
Attachments
Re: SEWA
To shield the source from looking directly into the zener diode, which can make some sources unstable.
hifryer said:
To shield the source from looking directly into the zener diode, which can make some sources unstable.
BOZ
Would BOZ be better if cascoded?
See distortion spectrum analysis pics in Nelson's cascode article on his other site!
See also Pearl second stage.
Then again removing 2nd harmonic distortion might make it sound like
any other SS pre??
cheers
Would BOZ be better if cascoded?
See distortion spectrum analysis pics in Nelson's cascode article on his other site!
See also Pearl second stage.
Then again removing 2nd harmonic distortion might make it sound like
any other SS pre??
cheers
Maybe. Probably. But then it would not be a BOZ anymore 😉 Nelson never did it with the Aleph series preamps though. Now I think he is using cascoded JFET stages in his preamps.
If you have the opportunity to try with just a condensator instead of the transformer.🙂 But why use a 2,4K/600 why not 5k/5k for example?
Tyimo said:
Yes indeed, it's working very nicely. Just the kind of pre SEWA (also very nice with the original Zen i guess) needs. It has a little more "bite" in the treble ans sounds "faster/quicker" (comparing with BZLS and X2r0) 😉 😀
Transformer Choice
Wanted to assure the drive impeadance was low enough, the 6C45 has a gain of 34 or so with the 2.4K/600 transformer should give an overall gain of about 17, should be just about right. Edcor does not have an xseries 5k/5k.
Ryssen said:
Wanted to assure the drive impeadance was low enough, the 6C45 has a gain of 34 or so with the 2.4K/600 transformer should give an overall gain of about 17, should be just about right. Edcor does not have an xseries 5k/5k.
1:1 Transformer
If you want 1:1 ratio you could use a Lundahl LL1671/30mA in the Alt-S connection
http://www.lundahl.se/pdfs/datash/1671.pdf
I'm sure it's a great transformer at $95.00 each. I used Lundahl transformers in my 300B amp and it was without fault.
The Edcor is about $11.59 each. Since the Edcor is so inexpensive, I may try it first and go from there.
If you want 1:1 ratio you could use a Lundahl LL1671/30mA in the Alt-S connection
http://www.lundahl.se/pdfs/datash/1671.pdf
I'm sure it's a great transformer at $95.00 each. I used Lundahl transformers in my 300B amp and it was without fault.
The Edcor is about $11.59 each. Since the Edcor is so inexpensive, I may try it first and go from there.
I happend to have a pair of Edcore 10K/10K but maybee thats to high,and it doesn´t fix the to high gain.Any opinion?🙂
Edit: does the 6c45 have a gain of 34 even at that low voltage?
Edit: does the 6c45 have a gain of 34 even at that low voltage?
10K/10K Transformer
Ryssen,
The B+ in the circuits I have posted is aprox. 150VDC and should be about 34 gain. Is the transformer gapped? If not you can use the 10K/10K transformer I would parafeed. I would not recommend the 10K/10K directly connected to the plate as the tube likes to run at least 15mA.
Ryssen,
The B+ in the circuits I have posted is aprox. 150VDC and should be about 34 gain. Is the transformer gapped? If not you can use the 10K/10K transformer I would parafeed. I would not recommend the 10K/10K directly connected to the plate as the tube likes to run at least 15mA.
I don´t know it is the one you can find at their website,it says it should take 50mA so it should not be a problem.
10K/10K
I think this might be the data sheet
http://www.edcorusa.com/classx/matching/xsm/XSM10k-10k.htm
Should be worth a try
I've icluded a clip of the 6C45 data sheet, the claim is 54 for an amplification factor +/-16, my experience with only a resistor on the cathode is about 34-40, adding a cap to bypass the resistor will raise that a bit.
I think this might be the data sheet
http://www.edcorusa.com/classx/matching/xsm/XSM10k-10k.htm
Should be worth a try
I've icluded a clip of the 6C45 data sheet, the claim is 54 for an amplification factor +/-16, my experience with only a resistor on the cathode is about 34-40, adding a cap to bypass the resistor will raise that a bit.
