Tube suggestions

[battradio]

A tube that would work good with those transformers is 6GT5's , the sreen voltge would have to be changed but they are cheep .
http://www.tubesandmore.com/search/node/6Gt5
http://www.nj7p.org/Common/Tube/SQL/Tub ... Type=6GT5A

[Impmon]

Hi guys,

This is a spin off from my Bogen thread, but my ST-70 mono project got me really thinking about this build.

I have been thinking about the 680V B+ the doubler produces, and I'm not too intimidated by it, but it looks like I could have a fairly stiff 350V supply off today's wall voltage with the same transformer using a FWB.

The first tube that comes to mind is the 6L6, and the filament voltage will allow for a six pack per output transformer.

Despite what several people have said, I test the output iron at almost all frequencies at 4.7-5.2K, so lets call it a 5K.

How would the six 6L6 tubes do into 5K?

That many 6L6s will be very under utilized into 5K, which would be more like what a single pair of 6L6s running Class A would like to see. If you go with a 350V DC rail, then you might consider the horizontal deflection finals. 6CB5s, 6DQ5s, are real beasts that like low voltages and low plate loads. Even a relative "pipsqueak" -- the 6BQ6GA -- produced nearly 40W with 350Vdc into a 4K4 (P-2-P) OPT that was an off-the-shelf item originally intended for PP, Class A 6L6s, and was underrated at 30W. Running open loop, the 6BQ6 makes mostly H3, and doesn't have that "pentode nastiness", just an overly "edgy" or "aggressive" sound. A little gNFB takes the edge off.

A fairly stiff PS is just what you need for these types. They also sound very good, despite not having any audiophool pedigree (that keeps them cheap) and no audio use mentioned in the spec sheets.

If you really want some speaker-poofing power, consider the 6LW6 and it's variants/cousins. A pair at 400Vdc will get you north of 100W easily. The H3 estimate looks pretty good, but it's pretty deep into Class AB. Being a HD type, you might be able to spec bust and run a bit hotter.

Vpp= 400Vdc
V22= 110Vdc
Ipq= 100mA (Pd= 40W static)
Vgk= -23.44Vdc
Rl= 430R (nom) / phase
Ip(max)= 779.17mA
Po= 130.53W
Pd= 33.94W (dynamic)

I0.5= 391.67mA
H3= 0.36%
P1= 10.89W