Vox Cliff Richard Reverb Unit Schematic

[alan52]

Hello All,
I have a 1960's all tube Vox Cliff Richard Revervb unit Model "REV" by JMI-Jennings Musical Instruments and I was after a schematic diagram.

This reverb unit takes 2 guitar inputs as well.

These are pretty rare reverbs now.

I have looked at variuos sites and theres a lot of Vox schematics but not for this model even from the Vox site itself.

My reverb isn't working anymore because the crystal phongraph cartridges made by Acos model GP71 have had it.

You just can't fit a standard off the shelf reverb tank to it.

It would be nice if I could find out the specs for the ACOS GP71 crystal phongraph cartridges as well. I think I could get some other part to fit.

Anyhow, if anyone out there could supply me with a schematic or lead in the right direction to get one it's much appreciated.

Cheers
Alan52

[g1]

There may be schematics here: The Amp Garage :: View topic - Vox Reverb Unit schematic
I can't see as you have to become a member to see if the attachments are still there.
Some info about the crystal carts here: Vintage Amps Bulletin Board ? View topic - Old Vox piezo reverb tanks

[vintagekiki]

http://www.vintageamps.com/plexiboard/viewtopic.php?f=2&t=107325

Schematics
http://i.imgur.com/PT6Ksk1.jpg

[Mick Bailey]

Maybe the unit would be better converted to use a high-impedance capacitor-coupled tray intended for an Ampeg. Replacement cartridges are hard to find in decent condition and with enough life left in them to justify the cost.

[Audiotexan]

I feel stupid asking this... but what am I missing?

In the circuit that vintagekiki kindly found and provided, I notice that it refers to "input transducer" and "output transducer".

Now, I'm not a *complete* idiot (though my memory fails me at the most embarrassing times it seems)..and I do know that a transducer is typically referred to in the speaker sense (at least in modern terms), and am aware of the generally accepted definition: "A transducer is a device that converts a signal in one form of energy to another form of energy".

But for the life of me, am missing the boat. If the 1960s ad says 'point blank' "non-mechanical" then I take this to mean...no moving parts. Hence no spring tank. Ok, fine. No problem. Didn't see one in any of the wonderful gutshots posted

I can see the two 47k's strapped on the output jack, one of which is tied to the volume pot

but I'm not seeing c14 at all, much less showing it going to a transducer...

What am I missing/what are they referring to?

[J M Fahey]

I feel stupid asking this... but what am I missing?

In the circuit that vintagekiki kindly found and provided, I notice that it refers to "input transducer" and "output transducer".

Now, I'm not a *complete* idiot (though my memory fails me at the most embarrassing times it seems)..and I do know that a transducer is typically referred to in the speaker sense (at least in modern terms), and am aware of the generally accepted definition: "A transducer is a device that converts a signal in one form of energy to another form of energy".

You are right.
In this case transducers in one end get an electrical signal and mechanically vibrate the spring, in the other end they do the exact opposite.

But for the life of me, am missing the boat. If the 1960s ad says 'point blank' "non-mechanical" then I take this to mean...no moving parts.

You are forgiven for your confusion.
The ad writer wanted to brag on not having troublesome unreliable high maintenance motors, pulleys, wheels, heads and rollers as in "the other" Echo unit they sold at the time, and he poorly wrote no "mechanical parts" which of course is inaccurate.

Hence no spring tank. Ok, fine. No problem. Didn't see one in any of the wonderful gutshots posted

Oh yes you saw it, itīs the long silver rectangular subchassis in the bottom of the electronics section, stretching end to end and showing two NASA approved organic high resiliency suspension/damping devices, a.k.a. "rubber bands" , holding the floating sub subchassis with 2 ceramic pickup transducers and the actual spring.

Typical of Internet tubehead forums, they spend time and pictures on the magical tubes, suggest layouts, etc. ... and nobody cares about the most important and "difficult" part, the tank itself.

I can see the two 47k's strapped on the output jack, one of which is tied to the volume pot
[ATTACH=CONFIG]29539[/ATTACH]
but I'm not seeing c14 at all, much less showing it going to a transducer...

What am I missing/what are they referring to?

You are forgiven , THEY are missing it

Please post a couple pictures of your tank, with transducer/pickup mounting closeups.
Personally first I would try to revive it as original and only if impossible would build "something else" .

Iīm quite sure that most *any* ceramic cartridge will work there, popular Sonotone 9TA comes to mind, but the general principle is the same.
You will probably need to mount them in a slightly different way, no big deal.

Search EBAY or local Mom and Pop "Radio xxxx" electronics shops (or some retired TV repairman) to get a couple "record changer pickups" for peanuts.

Real crystal ones should be dead by now (dampness kills them), but ceramic ones basically have the same material as piezo disks ... and those last forever.

Absolute worst case you can use a couple piezo disks pulled from old tweeters, I do that myself, but it involves some sheet metal cutting and bending to make the subchassis and the small stands to support the disks properly.

Will post some pictures on my homemade piezo tanks (which work quite well) for reference.

[J M Fahey]

Some Vox piezo reverb pictures:







Detail on spring to needle attachment (epoxied/soldered?):

[Audiotexan]

Apologies to Alan52 for my minor hijack.

You are forgiven for your confusion.
The ad writer wanted to brag on not having troublesome unreliable high maintenance motors, pulleys, wheels, heads and rollers as in "the other" Echo unit they sold at the time, and he poorly wrote no "mechanical parts" which of course is inaccurate.

I hate friekin' Marketing departments. But what you say makes perfect sense. Didn't even think of the Echoplex/Tel-Ray factor. I was just wracking my brain thinking...all tube, and no springs??

Oh yes you saw it, itīs the long silver rectangular subchassis in the bottom of the electronics section, stretching end to end and showing two NASA approved organic high resiliency suspension/damping devices, a.k.a. "rubber bands" , holding the floating sub subchassis with 2 ceramic pickup transducers and the actual spring.

LMAO. Gonna have to try and remember the 'Nasa' bit.
But yeah. Missed the forest for the trees again. I saw the two black-dealy-bobs on the subframe and thought they were 'keepers' or such, as they looked like they somehow interacted with the back panel (that's removed). Never occured that they were keepers for the floating spring chassis. /facepalm

Typical of Internet tubehead forums, they spend time and pictures on the magical tubes, suggest layouts, etc. ... and nobody cares about the most important and "difficult" part, the tank itself.

So true.

Also, good info on the cartridges you mentioned here:
(including great pics on rebuilding and subs)
Vox_Supreme

And another on the varying impedances/mV ratings of cartridges
Vintage Amps Bulletin Board ? View topic - Old Vox piezo reverb tanks

Taken from the bottom link:

by nielDa on Sat Jan 19, 2013 9:53 pm

Hi all. I have two Vox AC10 SRT amps using ACOS GP-71 phono cartridges in the reverb section. The crystals in those cartridges, as you know, decompose over time (no use finding a new-old-stock replacement.) Would the Sonotone 8T ceramic cartridge work as a direct replacement, assuming I make some sort of adapter to attach it to the chassis screw holes?

The specification I found for the ACOS GP-71 cartridge says output is 200mV, load 1 megohms. For the Sonotone 8TA, output is 300mV, load 1-5 megohms. (For the Sonotone 2TA, which I also see referred to sometimes, output is 1.0V, load 2-3 megohms.)