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Janus I amp input question - RCA replaced 5-pin connector- will Suitcase work?

Started by Yaniv Brener, July 30, 2016, 07:23:34 PM

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Yaniv Brener

There's a guy offering me the Janus I amp with two separated 12" speaker enclosures. I like the idea of stereo separation instead of having it all in the vertical cab. I'm about to finally purchase my first Rhodes (suitcase, w Janus preamp, missing the cab so this makes perfect sense).

BUT- it seems someone replaced the 5-pin preamp cable and pre-amp output with RCA jacks. (see picture attached)

I'm getting the Vintage Vibe 5-pin power supply with stereo outs, so I was wondering: can I plug these 1/4" outs into the A+B "Power Amp Input"?
Or are they supposed to go into the "Pre Amp Output" that has now been cut out?

Looking at other amp pics, I'm having trouble figuring out what was supposed to go where. Got a bit more confused when I saw what seems like two amp models out there - the FR7710, and whatever I'm buying which I also found on ebay here:

Vs. these two FR7710

Is the only difference adding the master/slave output options? Sorry for multiple questions in one thread. They just kept coming  :-\

Ben Bove

The 5-pin amplifiers came in 2 versions - a no-label that was put into the suitcase cabinets, and the "Janus" model that came as 2 modular speaker cabinets, a Master and Slave, that were intended to replace the earlier "satellite system" of the Peterson design.  So if there's an actual Janus label on the amp, it was originally intended to be a master/slave speaker set paired with a preamp'ed stage rhodes.  These amps were not in suitcase pianos.

The subtle difference is that the Janus amp models have a gain adjust on the amp itself.  Otherwise, they're basically of the same design as a suitcase amp.

Naming conventions can be confusing in the Rhodes world, they never really did a great job differentiating models.  A "Suitcase piano" is confusing because a stage "looks like a suitcase" to everyday people, there is no such thing as a "Mark I Suitcase" because the Mark series was meant to be stage pianos... etc. so, the naming convention for all 5-pin amps has become a "Janus" to differentiate them by an era, even though that specifically refers to the wheeled amp cabinets for a stage piano.  So don't worry about the confusion.

My question is, do you need this Janus amp?  Reason being, is that the VV unit sort of replaces the need for a Janus power amp, the VV unit gets the preamp working and has a stereo out, to any 2 powered speaker monitors.  You basically don't need the Janus amp, and could go directly to this guy's 2 cabinet enclosures.  Ideally, you would purchase this amp at a discounted price and rewire the 5-pin adaptor on the Janus amp, so you can plug the piano directly in via 5-pin cable.  Otherwise, the VV unit and the Janus unit are duplicating the need for a power amp: they both do the same thing.  Power the preamp and create a stereo output.

If you used the VV stereo outs, yes they would plug into the "power amp input" as you're inputting the signal from the piano.  The "Preamp Outputs" are used to send the signal out to a recording device or other output devices like a mixer etc.

It would be nice to test the preamp outputs on the Janus unit, to see if they are in fact functional and everything is wired correctly... that it was just lack of a 5-pin cable that made the previous owner do the RCA jack mod.
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Yaniv Brener

Aha! I gotcha, thanks for clearing that up. Good to know I can still plug in. So the preamp outputs are basically the Send jack on a guitar amp.
The guy in the shop selling it (local guitar store, they don't know much about Rhodes) called VV and they set him up with the power supply, when I went to look at it he had already ordered the part and he wanted to sell it together.

Do I need the amp + speakers? Wellll...that's a borderline philosophical question right there  :o You're right, I can now already plug in to anything and power the preamp.
But, I only own one PA speaker, and my desktop studio monitors aren't doing justice to the sound with their stingy bass response. I guess I can go straight into the two inputs on the PA, but I do love me some wide stereo vibe. It's also less than half the price of another PA speaker, he's selling it for $200. It might have resale value, just judging by seeing a few amps up on ebay for ~3-400. The internal debate rages on...
Now of course, that's assuming it is in good shape internally and I can reattach the 5-pin connector.

I'll maybe surf the forum for that, I'm sure I can't be the first person asking about replacement 5-pins. Thanks for the help!

Ben Bove

$200 is not a bad deal, if he's selling you 2 speaker cabinets of some kind with it.  I can see how that would be cheaper than buying a modern-day powered speaker.

You can get a 5-pin replacement jack, and just refer to the amp schematic on which wire goes to which pin:

Depending on the cosmetic damage underneath that RCA plate modification, it might not be that bad.  Janus amps are also pretty resilient and usually don't have electrical components fail, just bad soldering connections where the connectors plug in to the boards.
Retro Rentals
Vintage Music Gear
(818) 806-9606

IG: @RetroRentalsNet


I've just recently bought a Fender Rhodes Stage (73) Mark I, from 1974. The previous owner also sell me a Suitcase (FR-7710, 5 pin) with the suitcase legs, so basically I am trying to convert a stage into a suitcase...

The Rhodes has the original stage preamp, with the common input/output plug...shall I change the preamp so I can connect with the 5 pins of the suitcase? Or I can plug it straight to the power input channel A of the suitcase?

Thanks in advance! :)
Guille Porto Garcia, happy owner of a Clavinet D6 and recently a Rhodes Mark I.

Cormac Long

When you say original stage preamp, you mean the volume and bass boost knobs?

If so, they are only passive controls and its likely the piano will not work correctly with the suitcase speaker input. I actually think those suitcase cabinet jacks are line outputs and not input jacks at all. But maybe they can double as line inputs. Someone else may be able to confirm this.

The more ideal solution would be to switch out the passive controls on the stage for a modern suitcase compatible preamp that can then connect to the suitcase cabinet with the appropriate 5-pin cable. That would let you at least get closer to the original suitcase setup.

You'd want to be certain the cabinet amp and 5-pin outputs/input are working beforehand.

There is also the concern that the sustain pedal would work correctly. The stage piano case baseboard is thicker than the original suitcase piano base. You've also got the leg sockets to be dealing with so there may need to be mods done to make the cabinet pedal rod work with the stage piano.


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There is no reason to use the 5-pin XLR unless you want the +and- 15V DC power for a preamp.

I recommend that you use the "power amp input" jacks to connect from your sound source to the FR-7710 amp.  I think this schematic matches your FR-7710 amp:  Zoom in to the upper left corner to see the input jack arrangements.

You will probably not be super happy with the Rhodes Stage Piano plugged in to these inputs, but if you put any kind of clean boost between the Rhodes Stage and the FR-7710 you can achieve happiness.  You could buy a Rhodes preamp, or you would be perfectly fine with a little mackie mixer (or even a cheaper alternative).  I like the mixer option, because it allows you to get EQ and as much gain as you will ever need, and it can provide left and right outputs from your mono source.

Let's hope you can get that amp running!