I'm not sure if anyone pointed this out yet, but the heater supply is already referenced to ground through the voltage divider, I would remove the ground connection ,at the heater supply,and remove the two 100 ohm resistors.
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BTW, B+ at 220 Volts seems a "bit" low, given the voltage on the base of the BF459 at 204,7 Volts and the upper 270K of the voltage divider....
Please be more concrete, in this case, what needs to change!
Maybe I should be like this:
thank you!
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Everything needs to change. Here is a link to a high end preamp:
http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/twinlineamp/schematicsht2scaled.jpeg
Cheers
Ian
Where to start?
Sorry to be a curmudgeon but try the usual suspects.
a) get rid of the silicon PN rectifiers and replace with quieter types. Schottkeys or valve diodes.
b) replace the anode follower with a current source or inductor or output transformer (eg LL 1660/10mA or better)
c) change the capacitor input filter to a choke input filter.
d) replace resistors in RC circuits with inductors.
e) 6DJ8 is a good tube but nowhere near the best - even a 6SN7 would (on average) be better.
Finally, a bit speculatively, replacing the series B+ regulator with a shunt regulator (eg. 0A2 ) is widely recommended by those who try it - if not so easy to clearly stand behind technically.
Is the anode resistor on the first triode *really* 4.7k?? That is far too small... The rest of the design is OK; I think other posters are being unnecessarily harsh. You don't need chokes or totem-pole stages to be 'high end'.
not sure what I see
input buffer with mu stage output ?
you wouldn't happen to have a good single channel I can use for my bass guitar ... any tube is ok 😀
not sure what I'm looking at there
but I might have figured out that the Reddi DI boards are your design
I forgot you also sell boards
but I might have figured out that the Reddi DI boards are your design
I forgot you also sell boards
not sure what I'm looking at there
but I might have figured out that the Reddi DI boards are your design
I forgot you also sell boards
The original REDD DI is not my design. Several people on groupdiy.com decided to build their own and some of them used one or two of my standard boards.
Cheers
Ian
Correct. The PCB is designed for a 6CG7 mu follower but it is easy to build it as an SRPP merely by omitting some components and replacing others with links. It works fine as an SRPP with a 6922 (industrial version of the ECC88).
Cheers
Ian
Because the idea of the REDD DI is to add tube tone to a bass guitar. The 6CG7 is a very linear tube and the mu follower is a very linear topology - not much tone there. The 6922 is a less linear tube and the SRPP is a much less linear topology so both changes add tube tone.
Cheers
Ian
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