Schematic Posted

[glasman]

I posted the schematic in the files section (in it's current form) for the Rev-A-Loop.

Gary

[Funkalicousgroove]

Thanks, that is just what the DR. Ordered!! I've been working on that very same idea myself, but if yours is tried and works then I'll just build a Glasworks!

[glasman]

Thanks, that is just what the DR. Ordered!! I've been working on that very same idea myself, but if yours is tried and works then I'll just build a Glasworks!

If nothing else it is a good start to experiment with for future toys.

Now to see if I can add Vibrato!

And it is WERKS

Gary

[ElectronAvalanche]

Hi Gary,

thanks for sharing the schemo.

I will try the paralleled recovery section on my ODS75W. I still have two gain stages and too much noise and gain because of that!

Concerning ground loops:

I think I will need to approach the grounds in my amps a bit more scientific. My 100W ODS is dead quiet, but the 75W ODS has some nasty hum.

My Vibroverb clone has a bit more hum than I like albeit I got rid of the Fender grounding scheme (random grounding as Kevin O`Connor calls it).

I will definitely tackle a Reverb A Loop in the near future.

Have you thought about putting a Mix control into the device to be able to use the Loop either parallel or in series?

Cheers,

Dominik

[Bob-I]

Thx a bunch Gary.

Now... if it just had a Magnatone type tremolo too

[Luthierwnc]

Can't help with the Magnatone trem but many moons ago I built a stand-alone trem using the brown Fender (G-A) trem. This was the last one before Fender started using the roach. The tremolo uses five triodes so the sixth was used to create the line signal. It is a complicated circuit but is really cool sounding. Basically it is a high-low band pass so you get different wobbles at different frequencies. With a pot on the first stage I also got a welcome bit of gain when the trem was bypassed.

I sold that one with plans to make it into a combination OD and reverb box but never followed through. The issue was whether to run it in parallel or series with the reverb and/or how to drop it completely out of the circuit for the more usual case of not needing it. In looking at Glasman's schematic it looks like it could be tied in at the FX send/return with a relay. The Fender "G" trem only uses two 12AX7s so it might be possible to pull the driver off the plate of the input triode and only bump the tube count by two. Fender has the patents for the trem circuits. I don't know if they are still in effect but, of course, this is a purely theoretical discussion.

FWIW, Skip

[Bob-I]

Now to see if I can add Vibrato!

I've always been interested in trying to duplicate the Magatone true Vibrato. My understanding is that by modulating different frequency ranges at different speeds it fools the ear into thinking it's pitch modulating. A friend had one of these amps in the 60's and it was an awesome sound.

[glasman]

Now to see if I can add Vibrato!

I've always been interested in trying to duplicate the Magatone true Vibrato. My understanding is that by modulating different frequency ranges at different speeds it fools the ear into thinking it's pitch modulating. A friend had one of these amps in the 60's and it was an awesome sound.

Yup, they definately had a unique sound. I think it is the amp of choice for Lonnie Mack. You can really hear it in his recordings.

Gary

[Luthierwnc]

I looked into cloning a Magnatone 280 back when. The hitch was that a repairman who specializes in those amps had cornered the market on the diodes they used. I would be interested in knowing if someone has come up with an alternative or if the supply has freed-up.

That is a true vibrato or pitch shifter. Trems just alter the volume.

Skip

[Bob-I]

I looked into cloning a Magnatone 280 back when. The hitch was that a repairman who specializes in those amps had cornered the market on the diodes they used. I would be interested in knowing if someone has come up with an alternative or if the supply has freed-up.

That stinks. I've read that it's hard to find the right parts, plus it takes more than 50V on the bias to drive them.

That is a true vibrato or pitch shifter. Trems just alter the volume.

Skip

Not exactly. It's actually a trick on the ear. They modulate the highs on a different phase than the lows and it sounds like vibrato even though it's actually just tremolo.

[Robert]

Gary,
Thank you for sharing your newest project with us! Liked the sound clip demo as well.

[v00d00blues79]

Gary,

question on the PT that you used. What was the voltage on the secondaries?

Thanks,

Andy

[glasman]

Gary,

question on the PT that you used. What was the voltage on the secondaries?

Thanks,

Andy

I don't have my notes with me here in Holland, but as I remember it it measured about 580v CT. Anything that will deliver 400Vdc or so will work. The Hammond Flat packs with a voltage doubler would be fine for this circuit. Currect requirements are minimal.

Gary