vibrato circuit

[grtamp]

Hi , I want buid an amp with Vibrato circuit but I don't know what to use: opto or bias modulating type?.

What you suggest me?

There is a great differences between them?

Thanks

R.

[Blackburn]

I think this calls for the vibratoking. I'll light the beacon.

Bias modulating type... The single triode version like the Princeton. It's hypnotic, and very simple.

[crbowman]

The old brown Fender Concert 6G12a has a really wonderful vib/trem circuit with no opto-oscillator.
Check it out:

http://el34world.com/charts/Schematics/ ... _schem.pdf

[Stevem]

The question is do you want true vibrato as in the 6G12 that needs two full duel triodes to get it done, or just plain old tremolo like 99 % of all amps have including Fender?

[Blackburn]

The question is do you want true vibrato as in the 6G12 that needs two full duel triodes to get it done, or just plain old tremolo like 99 % of all amps have including Fender?

I think you're referring to the LDR (Roach) circuit with the 99% bit. For an economical space saver that is still spectacular, the single triode bias modulator is a great choice. There's nothing like the harmonic trem like in the blonde Twin or brown Pro, but then you kind of have to build the amp around that circuit. More components there than in many simple amps. the brown and blackface Princeton's single triode is great and you still have room for a complex pre, if you want it. My $.02.

[xtian]

I love the simple bias-vary trem. But in my build, I had to adjust the amp's bias pretty low to get the depth I want in the tremolo. Probably needs some troubleshooting, but works great as is.

[grtamp]

Hi , I have one socket only in my chassis , I can use a double triode only!

6G16 vibroverb?

[Phil_S]

You might enjoy and derive some benefit from reading this http://www.lynx.bc.ca/~jc/tremoloCircuits.html
I wouldn't bother with a roach (LDR).

[grtamp]

thanks all for the input , I think to go with this:

[Phil_S]

Good choice. I think you can get the 3M RA pot from Weber.

[xtian]

Good choice. I think you can get the 3M RA pot from Weber.

Also here:

http://www.tubesandmore.com/products/R-VC3M-RA

[grtamp]

Thanks all!!

[Blackburn]

FWIW, I built that trem circuit and IMO it doesn't hold a candle to the single triode circuit found in the Princeton. I've rolled tubes and it just isn't as dynamic. I'd say it's worth not using the extra triode to get a better, more economical circuit that isn't as much to lay out. Maybe add an extra stage in the pre? Just my $.02.

[grtamp]

for the 0.02 uF caps ,can I buy polyester/film caps or I have to buy ceramic?

Thanks

[tubeswell]

The various fender 'trem and vibrato circuits all have their peculiar quirks and their attractions.

For bias-vary trem, I reckon you can't beat the 5G9. It has the right combination of LFO strength and 6V6 bias to really get a trippy hypnotic slam going (see attachment of me playing a strat through my home-brewed one with a home-brewed 6G15 in front)

The blackface tremolux/vibrolux bias-vary trem doesn't quite have the same mojo, because you can't run the 6L6s with enough voltage to make them sing, and at the same time supply enough slam to the 6L6 grids to really make them slam - its one or the other.

The brown vibroverb trem is a very similar system (and was the precursor to the BF tremolo/vibrolux trem)

Whereas the brownface harmonic vibrato amps are really sweet and musical sounding with subtle and complex harmonic overtones (but that's a completely different way of getting 'trem')

The blackface AB763 amps (and silverface derivates) using the roach have an on-off quality that produces a nice intensity, and won't wear out your output tubes as fast as bias-vary trem on the output stages will.