[SEL] OT: The Hammond's Singing Again!

[John Culp]

They're 6V6GTs. The old ones in it are still good. I found a couple of 
used ones in my tube stash, one of which is low on emission to the 
questionable point, but didn't have to use them in this case. There are 
new Russian made 6V6s available, most of which have a reputation for 
not surviving long in Fender guitar amps (which run them at a higher 
plate and screen voltage than they were spec'd for.) I've read on the 
Web that the Hammond M3's transformers are overbuilt enough to safely 
use 6L6s in it. Looked at the tube charts and figured with the M3's 
fixed bias using 6L6s it would move from being a Class AB1 amp to a 
Class A with nearly
2 1/2 times the plate current (= waste heat) and only a few watts more 
output power, but it'd still be in a safe plate dissipation range for 
the 6L6s. An interesting thought is that this organ uses an 
old-fashioned field coil speaker, with the field coil serving as an 
input choke on the power supply. The boosted tube current draw would 
increase the magnetizing force on the speaker field and might increase 
the speaker's sensitivity. All in all, though, I think it best to stick 
with original spec parts in vintage gear.

For guitar amps, ElectroHarmonix has sold Russian 6L6s labeled as 
"6V6EH" for use in 6V6 amps!

The 6Y6 and 6W6 series tubes can substitute for 6V6s in some cases. 
Wouldn't try it in the high-voltage guitar amps, as they're rated for 
lower voltages than the 6V6. With a fixed bias, I'd have to study the 
tube plate characteristic charts a while before trying a swap.

John

On Jan 30, 2005, at 7:19 PM, Skip Cleveland wrote:

> What are the power out put tubes in this thing? Are they 6L6s or even 
> 6V6s. Also, where do you get replacements?
> Skip


John Culp
Bristol, Tennessee, USA