|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
63.246.183.223
In Reply to: RE: What I have so far posted by PeterI on May 13, 2015 at 11:48:59
"What I don't want to end up with is an amp like the HK A300 or A500"
That's exactly what you're proposing to build, at least in terms of the output section. The Cit V is essentially a more powerful version of the A500 power amp topology. FWIW, I just finished testing a prototype using the A500 as a foundation, and the results were very, very good. I changed the 7355 output tubes to a 6L6 variant, grounded the cathodes and applied fixed bias. THD/IM and frequency response were excellent, and I believe performance will be even better in the final build ('SL7s and 'SN7s in place of the minis). Just to be clear, this is the A500 power amp/power supply only, no preamp or tone controls. I was never satisfied with the control sections of the amp, so it's being modernized on a new chassis without them.
--------------------------
Buy Chinese. Bury freedom.
Follow Ups:
The Cit. 5 uses "routine" Mullard style topology. What's special is the high gm exhibited by the small signal tubes, particularly the 12BY7. High gm provides resistance to slew limiting induced by the GNFB HF error correction signal.
Higher gm is precisely why I suggested an ECC99, instead of a 6CG7, as the LTP phase splitter.
Eli D.
If you change phase splitter from 6CG7 to ECC99 (12BH7) what else do you have to change (besides heater pin wires)?
The triodes in the 6CG7 and 12BH7 are so close electrically that, most of the time, rewiring the heater connections is all you have to do.
The ECC99 is a different story. That type exhibits very high gm, very low R P , and a big heater draw. Given those facts, the ECC99 falls into a so called "super triode" group, along with the 5687 and the Russian 6n30p. What I find attractive about the ECC99, for service as the LTP in a Mullard circuit, is: its mu of 22, the highest B+ limit among "super triodes", and the smallest heater draw of the threesome.
Eli D.
What I like about it is that it's a drop-in replacement for a 12AU7. Thus you can quickly supercharge any vintage piece that uses 12AU7 either as a CF or in a gain stage, without re-wiring the socket. Of course, the PS has to be able to make the extra filament current and the B+ current needed to make the ECC99 sound its best. I also use it in cascode as a CCS in my preamplifier, which has a -250V supply.
Edits: 05/17/15
nada aqui
--------------------------
Buy Chinese. Bury freedom.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: