Help me identify my weird modded Stage 73!

[brennanmcnally]

I've had this Mk 1 Stage 73 for awhile, but only recently thought, "Wait, this isn't like all the other Rhodes pianos I've seen... most Rhodes don't need a power cable..."

Essentially it seems to have some sort of active preamp installed, as well as a second output jack (that seems to be wired to the original). It does not make any sound when the power cable is not plugged in. I'm relatively new to electric pianos, so any information I can get would be really helpful. Attached a few pictures, but happy to take more specific ones if that'll help anyone figure out what all this stuff is.

Thanks!

[Ben Bove]

By the blue boards, the shelf behind the logo, and right-mounted power and fuse, I'm guessing this is an Eddy Reynolds modification which would be great.  Any audio clip would be appreciated.  I've rarely seen stage piano conversions to active preamps, normally they're suitcase-only but this looks like his work.

[JVC (Mark V)]

Wow, that's pretty neat!  I want to know how the circuit is designed.  I see that tremolo is included too.

[ppeterso2]

I second all the replies here! That is awesome!  It looks somewhat modern with that IC, but then again, they've been around longer than I think sometimes.  With that transformer, they certainly thought of everything!

We need audio! lol

[brennanmcnally]

Forgot I even posted — wow, these replies are getting me excited!

I'll try to record some audio this week — have a pretty simple Apogee One, so I'll record something and move the knobs around and post that.

Where are you seeing vibrato? All I've been able to do is the treble and bass EQ on the stacked knobs.

Thanks guys!

[73 Keys]

Can you post a front view pic of all the knobs?

[brennanmcnally]

Can you post a front view pic of all the knobs?

Sorry for the long delay (5 months?!)! Pics of front knobs attached. I posted a picture of it to Instagram and Luke from Custom Vintage Keys here in LA instantly noticed that it was an Eddie Reynolds preamp.

Wow, that's pretty neat!  I want to know how the circuit is designed.  I see that tremolo is included too.

Where do you see tremolo? Any idea how I can activate it?

[vanceinatlance]

If it is not too much too ask, could we have a picture of the top of the blue perf board so we could see what the numbers on the ic chips are?  Someone spent some time putting that together building from the power supply up! I don't see anything indicating a tremolo circuit myself, but I could be wrong.
Thanks for sharing!

[laberge]

If it is not too much too ask, could we have a picture of the top of the blue perf board so we could see what the numbers on the ic chips are?  Someone spent some time putting that together building from the power supply up! I don't see anything indicating a tremolo circuit myself, but I could be wrong.
Thanks for sharing!

This would be amazing. Here's to getting an answer by February 2016

[brennanmcnally]

If it is not too much too ask, could we have a picture of the top of the blue perf board so we could see what the numbers on the ic chips are?  Someone spent some time putting that together building from the power supply up! I don't see anything indicating a tremolo circuit myself, but I could be wrong.
Thanks for sharing!

This would be amazing. Here's to getting an answer by February 2016

Ha! Sorry for the delay, guys. I'll be more on top of it from here on out.

Took some pictures of the blue perf board and other internals.

It's humming pretty bad when I play it... can't tell if it's a grounding issue or what.

[brennanmcnally]

[pnoboy]

Two of the ICs are NE5534 op amps, which are low-noise devices often used with audio.  There were used in one of the late-model Rhodes pianos (can't remember which model at the moment).  One of them would almost surely be used in the input stage.  Nowadays, one would want to use a wall-wart type of power supply to power such a preamp.  Putting the power transformer, which has a definite possibility of causing hum, near the harp, and then putting an ugly IEC connector up near the keyboard for a power cord seems inelegant to me.  If it were my piano, I think I would first decide if the preamp really improved the sound.  If not, I'd get rid of it.  If I did like the sound, I'd consider removing the power supply, covering the holes with an aluminum plate, and then using an appropriate wall wart supply.

[vanceinatlance]

Great pics! Thanks for sharing them brennanmcnally!
I do agree with pnoboy that the power supply could possibly cause noise in that location. If this is indeed an Eddie Reynolds verified mod, I personally would leave it alone just because I personally think that is an amazing cool thing to have and should be left alone for value and history.
I am not necessarily a fan of wall wart power supplies. These themselves , in my somewhat limited experience, can be very noisy and are usually built much cheaper than the one you have mounted in your rail.
That being said, using a wall wart would take the ac mains away from the piano wich is good for multiple reasons, and should accomplish moving power supply noise away from the piano. You can call me crazy, but, if it was not a ER mod and i liked the circuit, I would rebuild the power supply and move it outside the piano and into an enclosure of its own. Basically creating your own oversized wall wart..
I think I am basically mirroring pnoboys advise and suggesting "very nice wall wart" !

[brennanmcnally]

Great pics! Thanks for sharing them brennanmcnally!
I do agree with pnoboy that the power supply could possibly cause noise in that location. If this is indeed an Eddie Reynolds verified mod, I personally would leave it alone just because I personally think that is an amazing cool thing to have and should be left alone for value and history.
I am not necessarily a fan of wall wart power supplies. These themselves , in my somewhat limited experience, can be very noisy and are usually built much cheaper than the one you have mounted in your rail.
That being said, using a wall wart would take the ac mains away from the piano wich is good for multiple reasons, and should accomplish moving power supply noise away from the piano. You can call me crazy, but, if it was not a ER mod and i liked the circuit, I would rebuild the power supply and move it outside the piano and into an enclosure of its own. Basically creating your own oversized wall wart..
I think I am basically mirroring pnoboys advise and suggesting "very nice wall wart" !

http://ep-forum.com/smf/index.php?action=post;topic=8672.0;last_msg=47772#postmodify

Man — thank you all SO much for all the info! This is helpful beyond words.

It used to have no hum at all. It sounded fantastic. I noticed that if I rested my pedalboard on top of the piano, that would sometimes create hum (even when the board wasn't on or plugged in to the piano). Moving the pedalboard would eliminate hum. I currently have a Moog Little Phatty synth on top of the Rhodes, but moving it doesn't eliminate hum. Nothing changed inside the piano! My building was built in 1938, but I haven't had much trouble with the electricity here before, and I've had no problems with any of my weird finicky vintage amps.

Also — without the power cable plugged in, the Rhodes doesn't make a sound. Is there a way to bypass the preamp and hear the piano passively?

[brennanmcnally]

Two of the ICs are NE5534 op amps, which are low-noise devices often used with audio.  There were used in one of the late-model Rhodes pianos (can't remember which model at the moment).  One of them would almost surely be used in the input stage.  Nowadays, one would want to use a wall-wart type of power supply to power such a preamp.  Putting the power transformer, which has a definite possibility of causing hum, near the harp, and then putting an ugly IEC connector up near the keyboard for a power cord seems inelegant to me.  If it were my piano, I think I would first decide if the preamp really improved the sound.  If not, I'd get rid of it.  If I did like the sound, I'd consider removing the power supply, covering the holes with an aluminum plate, and then using an appropriate wall wart supply.

Any idea how I could switch off the preamp and hear the piano passively? As it is, it doesn't make a sound unless it's plugged in.

It's just strange that it started humming out of nowhere. Used to be fine, and nothing that I can think of changed in or around the piano. Could there be a grounding wire or something in the piano that is touching something it shouldn't?

(sorry for the completely amateur questions!)

[Cormac Long]

For immediate results, the only way you're going to get a passive signal out is to disconnect the harp RCA and run a cable from there direct to an external amp, pedalboard etc.

I was trying to see if the left-most Jack was possibly a passive out from the harp but it really seems to be parallel wired to the other jack.

[Pianet Martin]

If it used to be hum free and has got worse over the years, the hum might be down to the filter capacitors in the power supply deteriorating.  It's quite common to have to replace them after a couple of decades or so on any sort of equipment.  Those would be the two big orange capacitors on the power supply board. 

[brennanmcnally]

If it used to be hum free and has got worse over the years, the hum might be down to the filter capacitors in the power supply deteriorating.  It's quite common to have to replace them after a couple of decades or so on any sort of equipment.  Those would be the two big orange capacitors on the power supply board.

What I noticed when it first started humming was that if I twisted the instrument cable in the piano's jack, certain points wouldn't hum. I would have to rotate it and find a spot that didn't hum, BUT I've basically ruled out the cable being the problem by trying 3-4 different cables (plus I use them all on guitar and bass and have never had a problem). Now no amount of twisting or fidgeting fixes it. Hmm!

[brennanmcnally]

For immediate results, the only way you're going to get a passive signal out is to disconnect the harp RCA and run a cable from there direct to an external amp, pedalboard etc.

I was trying to see if the left-most Jack was possibly a passive out from the harp but it really seems to be parallel wired to the other jack.

I stared at the jacks, too — they're parallel wired. Must be for running into two different amplifiers. Would've been fantastic if one was passive!

[pnoboy]

For immediate results, the only way you're going to get a passive signal out is to disconnect the harp RCA and run a cable from there direct to an external amp, pedalboard etc.

I was trying to see if the left-most Jack was possibly a passive out from the harp but it really seems to be parallel wired to the other jack.

I stared at the jacks, too — they're parallel wired. Must be for running into two different amplifiers. Would've been fantastic if one was passive!

I'd like to echo Cormac's suggestion.  Not only will running a cable direct form the harp to the amp/pedal board allow you to hear the direct sound of the harp, if will also allow you to check to see if the hum is still there or not.  You could try turning the active preamp on and off while running the signal direct to see if just having it on causes hum.

[brennanmcnally]

For immediate results, the only way you're going to get a passive signal out is to disconnect the harp RCA and run a cable from there direct to an external amp, pedalboard etc.

I was trying to see if the left-most Jack was possibly a passive out from the harp but it really seems to be parallel wired to the other jack.

I stared at the jacks, too — they're parallel wired. Must be for running into two different amplifiers. Would've been fantastic if one was passive!

I'd like to echo Cormac's suggestion.  Not only will running a cable direct form the harp to the amp/pedal board allow you to hear the direct sound of the harp, if will also allow you to check to see if the hum is still there or not.  You could try turning the active preamp on and off while running the signal direct to see if just having it on causes hum.

Thanks for the suggestions (and for taking the time to look at my Rhodes)! How exactly would I run it straight from the harp, bypassing the preamp?

[Student Rhodes]

Thanks for the suggestions (and for taking the time to look at my Rhodes)! How exactly would I run it straight from the harp, bypassing the preamp?

The back left part of the harp has an angled piece of metal with an RCA jack on it.  If properly connected, the preamp should be currently plugged into that jack.  You'll need to take the signal from their using a RCA to 1/4" adapter, available at Radio Shack for about six bucks.   Unplug your preamp, plug your guitar cable into the adapter and plug the adapter into the RCA jack.  Lastly, plug your 1/4" cable into your guitar amp.  You can also run directly from the jack on the harp into a mixer or recorder as well.

[JVC (Mark V)]

Wow, that's pretty neat!  I want to know how the circuit is designed.  I see that tremolo is included too.

I have to take it back, I think this is just a op-amp based preamp, mounted on Rhodes. I don't see circuit for tremolo.
So, I don't think it is anything special.  I think the circuit (or resulting output) is not much different from Velleman K4102 Guitar Headphone And Preamplifier kit.

By the way, I modded my Rhodes to replace RCA jack with 1/4" jack, so that I can plug in 1/4" TS cable directly.

[pcola_rhodes]

Does anyone know if Eddy Reynolds is still around?

I'd love to have his modification to my suitcase preamp...

[brennanmcnally]

Does anyone know if Eddy Reynolds is still around?

I'd love to have his modification to my suitcase preamp...

I don't think so... can't really find too much information on the guy online. But I'm also a total newcomer to this world!

[Ben Bove]

I thought I came across something somewhere where he went into electronics.  Whether it was IBM or something else, but as far as the piano world - not that I'm aware.

[The Real MC]

Seeing nothing but 5534s, I'm skeptical of them in a Rhodes preamp.  They may be low noise, but their input impedance is not very high - the TI spec says its typical is 100K.  Frankly that is low for an opamp.  I have DIs that are 100K input impedance that suck tone when I plugged my Rhodes into it.  It took a DI with 10M input impedance for the tone to not suck.

[pnoboy]

We have to be careful when judging impedance.  Most of the time, the input impedance spec in the datasheet is the differential input impedance.  If you use the op amp in a noninverting configuration, most of that impedance will be bootstrapped out.  Also, Fender typically did not use very high impedance connections to the harp.  The old Peterson preamps used 33k, the late-model suitcase pianos http://www.fenderrhodes.com/pdf/late-mark2-suitcase.pdf used an NE5534 op amp with a 46.4k input resistor, and the stage piano used a 10k pot.

[brennanmcnally]

Anyone still remember this thread? Anyways, I've just been taking the lid off and plugging straight into the harp. Sounds great — all the hum and noise was coming from the preamp. Bit of a hassle taking the lid off every time I want to play it (I have a Moog stacked on top and other miscellaneous stuff). It could use a setup, so I might just take in and have someone look at all this weirdness and figure out what to do! Although for the cost of repair, I'm tempted to just pick up another Rhodes — friend bought another Mk 1 Stage 73 in great condition for $550 locally over the weekend.

[Ben Bove]

You can actually feed a 1/4" cable out of the left side of the piano.  Have it plugged into the harp with the lid off, and when you put the lid back down, position the cable right in the middle of the left side of the harp cover.  it should squeeze in between the tolex case and the harp cover, without having to pick it up every time. 

The easiest solution to this piano if you're not feeling the preamp, would be to buy any Rhodes stage rail on ebay, and swap the name rails.  You can also reach out to the retailers like Vintage Vibe for example, and they usually have used stage rails lying around they would sell. 

I'd be interested in restoring your preamp if you'd like to sell it, feel free to PM me.  Thanks