Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bruno on April 27, 2010, 02:47:58 am
-
Is it possible to make this tremolo circuit work and chaging the amp to cathode bias rather than fixed?
tks
-
Here's the 5E11 schem (for the convenience of "helpers").....G
http://www.el34world.com/charts/Schematics/fender/VIBROLUX_5E11.pdf
-
Yes. Put a 250R and 50uF cap between the 6V6 cathodes and ground. Next, refer to the layout diagram that Geezer posted. Disconnect the wire between the board and the left lug of the depth pot. Now connect the left lug of the depth pot to ground. That should get you in the ballpark, may even be a homerun.
-
Easy: connect the trem section to the 6V6 cathodes after converting to cathode bias. Works, but the trem could be very weak because a single triode oscillator doesn't output a lot of juice - OK with high slope tubes such as EL84's, marginal with 6V6's.
-
I'd tend to go with Sluckey's method, because a 12AX7 plate isn't going to pull a lot of current. Which likely means very little change of voltage on the 250 ohm cathode resistor. I'd also want to double-check the value of the bypass cap to make sure it has significant reactance at 2-10Hz where the trem is likely to be operating.
So I'd think the output tube grid and depth pot would be a much easier load than an output tube cathode in this case.
-
is it me or the vibrolux is a bit differente than the rest of the tweed and brown bias modulated tremolos? Even the tweed 5G9 tremolux.
Also the 5E9 tremolux seems to be quite different too, I'm looking for a tremolo that is responds nicely to pick attack.
-
I built a 5G9 a couple of years ago and it is still my favourite tweed amp, (above a 5E3 and a 5F6A and a 5F2A that is to say, which are the only other tweeds amps I have made) FWIW. The trem has a hypnotic quality that slams you into the middle of next week. (If you put a 6G15 in front of it, the result is pure rock'n'roll) I run a greenback G12 20 in mine and it has lovely breakup.
I was wondering how a 5E9A would sound, but I have a lot of other priorities on my to-do list before I go there.