5e9-a tweed tremolux build not tremoloing very much

[mort]

The trem is working but VERY subtle. With the depth knob at 10 it sounds like it's at 2 0r 3. It doesn't look like anything was missed but I'll keep looking...



The circuit is stock with the addition of 3 prong cord and a master volume added (dual 250k pot subbed in place of the 220k resistors). Would this effect the trem possibly? I know its a PI bias wiggle trem but I don't understand how it operates exactly. I can see voltage swinging on the PI tube. With the depth set to max, pin 1 plate voltage on the PI only swings a few volts but the grids are swinging by over 100v

I also just noticed that on the schematic it shows both cathodes of the PI tied together and connected to the depth pot, but on the layout it shows the cathodes NOT tied together, one goes to the depth pot and one goes to the bypass cap. I've built this circuit several times and I've always gone by the layout during assembly and never noticed the schematic showing something different. I just tried tying the cathodes together and that cancelled out the effect completely so I put it back to the way the layout shows.

http://www.thevintagesound.com/ffg/s...e9-a_schem.gif

http://www.thevintagesound.com/ffg/s...9-a_layout.gif

edit: never mind I figured it out. Bad tube but I thought I had replaced it but must have accidentally put same one back in. And there is no discrepancy between the layout and schematic, I mistook V3 for the PI when the PI is actually V2.

[Chuck H]

If you continue to have trouble with this you might consider the master circuit. I suggested a change from the typical "replace the 220k bias feeds with a dual 250k pot" circuit once for a poster with a bias wiggle trem. The only difference was that the pot wipers were on the PI outputs instead of the power tube grids. This preserves the trem circuit/bias circuit relationship regardless of the master volume setting. The poster said it worked great (though I never tried it myself ) I found my post on the matter but the image was apparently lost in that site crash when a lot of archives got lost or I would have linked it. It's pretty self explanatory, but I can draw it up again if you need it.

[pdf64]

Now it's working, how do you rate that trem arrangement, eg compared to more common bias wiggle applied to the power tube control grids?

[Chuck H]

Indeed. I've never heard one in a good working example. I did get to play an old and clearly in need of service Tremolux once. But believe me, that didn't count I've read good things though. I would have thought if it were great that we would have seen this type of trem used more.

[pdf64]

There's a nice youtube clip of a tweed trem https://www.youtube.com/watch?v=pXoRZnzgiEk
Not certain which exact model it is, though a 5E9/a seems a likely contender.

My WEM Dominator has a very nice bias vary trem but it's applied to a pre-amp so has a bit of speaker thump and bass cut with all the high pass filtering http://bmamps.com/Schematics/Wem/wem...nator_1965.pdf

I wondered if the way that the 5E9a applies the modulation to the shared cathode of the paraphase and its driver might be better with either/both of those issues?

[mort]

Now it's working, how do you rate that trem arrangement, eg compared to more common bias wiggle applied to the power tube control grids?

Sorry, didn't know anyone was posting on this thread til now.

I'm not sure that I've ever played one with the wiggle on the power tubes. Owned a brown Concert but that one is on a preamp tube I believe. But just generally speaking it's a very smooth and subtle effect. When the depth level is raised toward its max it does a complete on/off type trem but doesn't sound nearly as choppy as the LDR extreme trem. It basically sounds exactly like that video you posted. I'd bet up to $3 cash money that the one in the video is indeed the 5e9-a.