[sdiy] slightly OT: best tube tremolo? table radio amps revisited

[dave at westphila.net]

http://www.ampwares.com/ffg/ will take you to the fender amp field guide. 
Check out the Brown Super.  At the bottom of the amp description page
(rightside frame) you'll see a link to two variations, the 6G4 and the
6G4A.  The oscillator section of the 6G4A is a bit easier to understand at
first glance I think.  It's a classic fender trem oscillator with a
cathode follower and phase splitter, but they're just variations on a
theme.

Seems the fender engineers found some worthwhile improvement in the 6G4A. 
It required an extra 12AX7 compared to the 6G4, even though only one half
of it is used.  Fender was always very economically minded so if they went
to the trouble it was probably worth it.

Oh, and my estimate of tube count was a tad high - 6G4 uses just 2 12AX7,
6G4A 2 and a half.

> Do you have a link to this circuit?
>
> JH.
>
> ----- Original Message -----
> From: <dave at westphila.net>
> To: "Ken Stone" <sasami at hotkey.net.au>
> Cc: <synth-diy at dropmix.xs4all.nl>
> Sent: Monday, July 17, 2006 6:58 PM
> Subject: Re: [sdiy] slightly OT: best tube tremolo? table radio amps
> revisited
>
>
> The tremelo/vibrato found in the brown fenders sounds really good.  It
> splits the signal into high and low frequency bands and modulates them 180
> degrees out of phase.  Uses 3 12AX7 tubes to do it but it's much more
> interesting to my ear than the plain bias vary tremolo.
>
> Dave
>
>
>>
>> Have a look at web pages under the tube section for some odd
>> alternatives.
>> the beam modulator or VCA coule be both used, coupled with the LFO.
>> address in sig below.
>>
>> Ken
>>
>>>The tremolo designs that I've looked at are the one from the Vox AC4 and
>>> a
>>>couple of the Fenders. It looks like the Fender modulates the power tube
>>>bias, which seems like a cool idea, but I only see it on push-pull amps.
>> _______________________________________________________________________
>> Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
>> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
>> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>>
>>
>
>
>
>