diytube.com

Hi! I'm new in this forum.I'd like to show You my projects:

http://picasaweb.google.bg/azazello52/A ... 1150319842
1625 & 6S4P & GZ34 and Hammond 125FSE /in black box/

http://picasaweb.google.bg/azazello52/A ... 0421321074
6S4S & 6J11P
/I saw here guys from Diy audio projects forum..../

Heya Azazello, nice to see you here too! :-)

Gorgeous amps.

Cheers!

My last try.....
http://picasaweb.google.bg/azazello52/M ... 7675804578
30P1S /russian from 50 years/-triode mode - 60 ma, PCC88Tesla, /GZ34 and Hammonds 125FSE-
5 kohm in black box on left/. Trany in front is for 30 v heating!
Cathode caps - non polar. green Nichikon and Rubycon.
Sound is very close to 2A3!! Unbelievable tube!

Guess that's the kind of tube you can dig up almost everywhere in the East. But you have to go there and visit people that has access to old dusty stores ...

Stunning...simply stunning!!

Next my project:
http://picasaweb.google.bg/azazello52/A ... 9080153826
Great tube 6CH6-Brimar from Great Britain! 70 ma in little bulb!!
GZ34, transf. Hammonds 125FSE in black box on left side.
Preamp 6S4P /Russia/. 4 cathode caps ELNA Silmic. I like this dwarf with
power sound!

Hi Azazello,

Very nice builds!!

Can you share the scematic of the SE 6LR8 & EM80? I found some interest in the 6LR8 awhile back [didn't pursue it however], and with your addition of the EM80, it looks to be a really cool project..!

Thanks,

msmpe wrote:Hi Azazello,

Very nice builds!!

Can you share the scematic of the SE 6LR8 & EM80? I found some interest in the 6LR8 awhile back [didn't pursue it however], and with your addition of the EM80, it looks to be a really cool project..!

Thanks,

Of course....But Sunday I will post my project....tomorrow I will not home.
6LR8 is unbelievable tube /6-7 $/ with very clear sound!

Here is schematic of my project 6LR8 & EM80:
http://picasaweb.google.bg/azazello52/K ... 7227434082

Azazello, thank you, I will study it.
Good listening!

I am rather fond of low-watt projects myself and there are lots to do. I have some myself 3A3SE, darling, 6AQ6-SE, 6AQ5PP, 12A6-PP, 5998A-SE.

IF I were to go for another project, I'd look for 6L6-SE and 807-STC.

I've had excellent results in the 1 watt or less class using 12B4As and 6S4As (not to be confused with Russian 6C4C / 6S4S triodes) as well as 6BL7s SET amps, these are good with both triodes connected in parallel.

For 12B4As, just copy the basic "Darling" SET circuit, but use 12B4As in place of the 1626s.

6S4As have a relatively high internal plate resistance, around 3700 ohms, so a minimum of 11K ohms prmary is needed, a 5K OPT with these tubes will sound like "something that is found in large quantities in a cow pasture" ;-) 22 to 24 K is even better sounding, very sweet, but at a somewhat reduced power output. I use the vintage 11K or 12K : 4 ohm German radio SE OPTs (generally made by Telefunken in the 1950s). These are frequently available on e-bay from "testedtubes"in Germany.


With an 8 ohm load, they behave as 22 or 24K primary OPTs, and are a "match made in heaven" for 6S4As, even moreso than with 12B4As. Sorry, Jef Larson, but I found something to surpass the "Abraxas" design, even though excellent in its own right, the 6S4As go one step beyond...


6S4As seem happiest with a B+ around 325V, cathode biased with 390-430 ohms, and 22-25 mA plate current. They need a fairly modest 8.5 to 10V P-P to drive them and any low or medium mu triode is a good driver for them. 12AT7 or 12AX7s have far roo much gain for most intents and purposes.

6AH4s are very nice, for 1 to 1.5W out, and I still believe that the much maligned 6CK4s can be "tamed" and produce good SET sound.


/ed B in NC

EWBrown wrote:For 12B4As, just copy the basic "Darling" SET circuit, but use 12B4As in place of the 1626s.

Id like to give this a try but the links to the original Darling site are down/gone. Is this the original circuit and the one that will work?

http://www.pastisch.se/tubes/images/darling.gif

Thx, amt

That comes very close to the original Bob Danielak "Darling" design..

Just look on Tom McNally's site at http://tmamps.com/ , he has all the schematics preserved for out persual. My favorite configuration is with 12SL7 (or 5751) as the driver tube, 1K cathode resistor bypassed with 47-199 uF / 16V cap, and 100K plate resistor. 12SL7s are available dirt cheap. 12AX7s will also work with those values, quite nicely, though they will have somewhat higher gain. 12AT6s have a similar pinout to the 8532s / 6J4s, just don't use pins 5 and 6, as these are the two detector diodes, these are equivalent to half of a 12SL7 or 5751. Leave the diode plates unconnected, or just connect them directly to the cathode, they will have no effect on the driver stage operation, either way.

My preference is also for separate cathode resistors for each tube, rather than shared resistors, which can result in somewhat unbananced / uneven operation if there is a "greedy" or a weak tube.

/ed B

Thanks for the info. One question though. I see that most builders use a higher input impedance OT for the 12B4. I do remember reading someones post saying that a 5k/8ohm can work well, but I cant recall where that was.
So is there downside to using the lower impedance? Id like to use the 5k since I could also play with the 1626 as well, but not if its really not ideal. Maybe the GXSE 8 or 10k/4ohm for a 8 ohm load?

amt