Epiphone Ravoli

[SGD Lutherie]

making a suck circuit:

might try one of these:

they measure 5/8" by 1.25" by 1 5/8" and are 1.5 Henry rated. it is the closest thing i could find available to an original Gibby choke and i don't know how it would fit in the Rivoli. the round bobbin type chokes are available from Curtis Novak or SGD Lutherie (?) who is a member here.

these chokes are available from Nebraska Surplus listed under power chokes light duty. (CPW) MQA-13

Hey, thats's good to know.

Is the original choke still under that plastic cover under the bridge?

I had an EB-2DC. I removed the baritone switch and wired in a 6 position rotary and a Varitone circuit. It was far more useful than the bass remover circuit.

[AxShack]

OK folks. next instalment: 
I finally managed to extract the choke so I could replace the wiring, which had been chopped off !!
Now, I have it in hand, and have started the new wiring loom, I have come across a snag!!
I realised, having got the wiring diagram from Gibson, that there should be a 220k Resistor in the circuit!!
Now I am not an electronic engineer so this stuff blows my mind, but where in all that's Holy does it go into this loom?

Please see photos attached, and if someone can lead me in the right direction, I will be eternally grateful !

Regards

Dave

[SGD Lutherie]

I realised, having got the wiring diagram from Gibson, that there should be a 220k Resistor in the circuit!!

I removed that resistor from my EB-2DC. It gave me more output and a clearer tone. Apparently Epiphone did too.

One thing to realize is that the choke is always in the circuit. Without the baritone switch closed, it works as a midrange choke. With the switch engaged it bypasses the cap and removes all the low end.

What I originally did was to remove the resistor and then rewire the switch so it took the choke in and out of the circuit. I found those two tones more useful then the thin baritone setting. Later, I replaced the pushbutton with a 6-position rotary switch, and wired it up like a standard varitone, but with the caps tuned for the bass range.

I don't own her anymore, but here she is in her new home. Still with my mods.

[AxShack]

Interesting!  I think I might do the same, dispense with the resistor that is.  Thanks indeed for this information.

Seeing how nice your old bass looks reminds me that I need to source a Scratchplate.  The one and only source here in UK dried up long ago.

If there is a Rivoli owner on this forum, would it be possible for you to make a tracing of the plate so I can make one?

Dave

[chromium]

Nice bass and mods SGD!  I used a 3-pos toggle in mine and it gives the original two filtered tones at its extremities, and completely removes all the filtering in the center position.




I had drawn up that circuit at some point to show how it might be implemented in an EB-2 or Riv:



Note that I didn't bother switching the 220k resistor out of the circuit there, since I wanted to retain the original sounds.  That resistor works with the .02mfd cap and the choke to form a filter (actually two types of filters, depending on the original push button position like SGD described).  If you are removing the choke (inductor) permanently, then that cap and 220k resistor can come out too.

[Dave W]

If there is a Rivoli owner on this forum, would it be possible for you to make a tracing of the plate so I can make one?

Dave, if you start a separate thread for this up in the Gibson forum, it will be seen by more people, Rivoli and EB-2 owners who don't always look in this section.

[dadagoboi]

Dave, if you start a separate thread for this up in the Gibson forum, it will be seen by more people, Rivoli and EB-2 owners who don't always look in this section.

Maybe they should start

Axshack, note the plastic spacer on chromium's neck pickup, I have the same on my '67. It varies in thickness from heel to bridge.

My EB-2 is not accessible at the moment.  If someone doesn't have one readily available I'll try to get to it.

[AxShack]

Just thought you all might like to see the finished article!
Just made a scratch plate for it, and finished the setup.
The hipshot bridge does NOT fit directly to the mounting posts (the spacing is slightly out) so had to drill out the holes in the bridge to give it some space to manoeuvre, but am left with the mounting bolts proud of the bridge instead of being inside the mounting holes !!!
Otherwise, I am very happy with the outcome.  It sounds great - although the so-called BASS BOOST circuit is very subtle to my Tinnitus hearing !

Dave

[Rob]

I really like that look!

[AxShack]

Yep, it is a real classic.  Glad I don't need a new bass otherwise I might be making the owner an offer he cannot refuse !!