Twin Reverb tremolo

[vintagekiki]

About Vibrato & Tremolo

https://www.fender.com/articles/tech-talk/pedal-board-primer-get-to-know-tremolo
What is Tremolo

https://sites.google.com/a/davidmorrin.com/www/home/trouble/trouble-amps/fender-harmonic-vibrato
The principle of operation of vibrato and harmonic vibrato

https://www.guitargear.net.au/discussion/index.php?topic=30731
For those that can be interested in Vibrato circuits

https://el34world.com/Forum/index.php?topic=17118.0
AC30 Vib/Trem

https://el34world.com/Forum/index.php?topic=24391.0
Wurlitzer 44 amp project

http://bit.ly/W44ServiceManual
1952 Wurlitzer Model 44 Service Manual

https://el34world.com/Forum/index.php?action=dlattach;topic=24391.0;attach=75520
Wurlitzer 44 amp schematics


Schematic vibrato effect used in Vox AC30 and vibrato effect used in the Wurlitzer 44 are very similar (almost identical).

1)

[Sea Chief]

Just to get back on topic...

Sea Chief, are you going to try a new bug first? If your bugs are old, as in original, it could be worth a try. Lot's of reports about older bugs, uh, buggering the usefulness of the tremolo in that circuit.

Yes- I think this is the right idea: I didn't know the effect was all down to this one component's condition. I can't remember if its original either. But if I can't choose 1 from 10 then isn't it a bit of a 50/50 lottery at best, the new one will be any better tho?

Do they degrade over time?

[Chuck H]

Yes- I think this is the right idea: I didn't know the effect was all down to this one component's condition. I can't remember if its original either. But if I can't choose 1 from 10 then isn't it a bit of a 50/50 lottery at best, the new one will be any better tho?

Do they degrade over time?

Not a lottery. The difference in performance between new ones should be small as long as you buy from a respected vendor that is going to sell something they know their customers aren't having a problem with. If you bought a cheap one from Shady Jack's Guitar 'O' Rama off *bay for 30% less you might not get the best possible performer . Since old ones are known to detriment amp and trem performance it might just be that which you're dealing with since you have three old amps. I'd buy ONE. At around ten bucks it'll let you know if you should spring for two more. Otherwise it's back to the drawing board.

[Sea Chief]

Ok bought one from Hot Rox Uk decent vendor.. interesting to see the difference it makes. I emailed a colleague (likely the best ampmaker in UK) if he had one.. says he's not allowed to use/ not roHS compliant (cadmium). So for a DR tremolo he makes the brownface tremolo circuit instead.. says better: Ive tried a brown deluxe clone & trem was definitely better than my DR clone I had at the time: is there any way of redoing the Twin's trem circuit to brownface & do-away with the bug?

[vintagekiki]

... is there any way of redoing the Twin's trem circuit to brownface ...

Yes

http://schems.com/bmampscom/fender/twin_6g8a_schem.pdf

[vintagekiki]

About Vibrato & Tremolo part II

https://music-electronics-forum.com/showthread.php?t=47738
Fender Twin Reverb PR186

https://music-electronics-forum.com/attachment.php?attachmentid=51119&d=1542331115
Fender tremolo LDR replacement schematics

http://www.regiscoyne.com/tech/tremolo/
Mods and tips for Fender Tremolo circuits

http://www.geofex.com/Article_Folders/sstremolo/sstremolo.htm
A Solid State Replacement for the Fender Tremolo

https://www.premierguitar.com/articles/the-59-63-fender-concert-vibrato-1
The ’59-’63 Fender Concert Vibrato

http://surfybear.weebly.com/blog/harmonic-tremolo-using-jfets
Harmonic tremolo

https://www.youtube.com/watch?v=k2sS7yvbjQo
Fender '65 Twin Reverb Reissue Tremolo LDR Problem

1)
https://www.youtube.com/watch?v=PMlkTpCvpEY
Photoresistor Volume-Modulating Tremolo: Design and Function

https://www.youtube.com/watch?v=YNbRtfCwT0U
Tremolo mods for vintage amps

https://www.youtube.com/watch?v=do_0NdnX4bw
1964 Super Reverb Tremolo Mods

https://www.youtube.com/watch?v=V9RijIDFB30
Vibrato tick cure

https://www.youtube.com/watch?v=O4boNgaiSQo
Vintage Fender Amplifier Vibrato Fix

[Sea Chief]

Alot of info there vintagekiki.. ok thanks for those.

I bought another roach.. & indeed this has worked/ stronger trem & volume drop is slight: huge improvement. I had thought I put a new one in when I rebuilt this twin reverb, but obviously put the old'un back in.

I do get some motorboating ticks now tho, but only apparant when not playing.

Thanks all- & a happy new year.

[vintagekiki]

Happy new year

[nosaj]

Alot of info there vintagekiki.. ok thanks for those.

I bought another roach.. & indeed this has worked/ stronger trem & volume drop is slight: huge improvement. I had thought I put a new one in when I rebuilt this twin reverb, but obviously put the old'un back in.

I do get some motorboating ticks now tho, but only apparant when not playing.

Thanks all- & a happy new year.

http://www.geofex.com/ampdbug/vibrato.htm

From above link
Sharp tick in vibrato oscillator: On neon/LDR Fenders, on the neon bulb side of the module there is a 10M to one side of bulb, 100K to the bulb; from the 10M straight across the board is the gnd point of the LDR. Put a 0.02 cap from 10M/bulb to the ground point; this works by filtering the output of the oscillator.

Also I must say I am impressed with your behavior now. Keep it up and stay around.

Happy new years to you from across the pond.
nosaj

[Sea Chief]

&say happy new year nevertheless.

Sea Chief

[g1]

Glad to hear the trem bug worked. Happy New Year.