Rhodes MKI Suitcase Vibrato - Stereo Guitar Effect

[thedefog]

Has anyone here on the forum attempted to build a vibrato circuit similar to that in a Mark I Rhodes?

http://www.fenderrhodes.com/pdf/late-mark1-suitcase-janus1.pdf

I'm interested in creating something like it, but wanted to know if anyone had already done it or if a vibrato/tremolo exists that does the alternating treble and bass volume. I'm going to play around with the breadboard tonight and see what I can come up with.

[Taylor]

It's definitely a tremolo, not vibrato - probably fell victim to Leo Fender's inability to remember which was which. 

To me it doesn't look like the bass and treble get split - there's a baxandall tone control which does allow to control bass and treble, but the output of the tone control is mono. Then it gets split into 2 optical trems, which are lit up in antiphase (the LED for one will light when the other is dark).

So, unless there's something I'm missing (certainly possible), it looks like a bass and treble control, then an autopanner.

The circuit is bipolar, so slightly annoying to integrate into our 9v world. If you want to emulate this circuit, a baxandall followed by the Panneur by 4MS Pedals/commonsound (schems and pcbs available at his site, 4mspedals.com).

If you want to do the alternating bass/treble thing you're talking about, I'd go buffer->split into 2 chains, one with a highpass sallen key filter, the other a lowpass sallen key, then feed those separate outputs to the panneur circuit.

[PRR]

> alternating treble and bass volume

NOT alternating treble and bass volume.

I had the earlier suitcase, pre-IC, but worked just the same.

The "suitcase" has two amplifiers (in one chassis), two speakers left-end and two speakers right-end. Per Taylor's analysis, sound comes out the left, then it comes out the right, "panner". Over the width of a stage-piano, this gives significant shimmer over most of the room.

[thedefog]

I own a later MKI Suitcase Rhodes, so maybe I can elaborate a little bit better. On mine at least, the lower speakers on it produce more bass content, and the higher ones more treble content. So even if the actual tremolo circuit doesn't split the treble/bass sections up, it still functions that way at the output. That explains the treble/bass sound being alternated on the tremolo. I believe the earlier MKI Fender Rhodes suitcase pianos didn't split up the treble/bass sections like the later ones do, but I could be wrong. I have recording examples I can post on here of the one mike on the lower cone (bass) and another on the higher cone (treble) if you want to hear it, with and without the tremolo running.

I guess that would explain the missing part of this.

Either way, I think it would be a cool idea to have alternating bass/treble volumes as a tremolo, in stereo and/or mono.

EDIT: I found a couple tracks, but they don't illustrate it as clearly as I'd hoped they would. I might be using it in a session tonight anyway, so if I am I'll do a test run real fast to put on here.
http://www.thedefog.com/media/rhodes.mp3
http://www.thedefog.com/media/rhodes2.mp3
The first one has Bass on left, Treble on Right. Second is the reverse of that.

[Mark Hammer]

Okay, that makes sense of the seeming discrepancy between the sound and the schematic.  Nothing in the schematic would suggest anything more than an autopanner, but obviously nothing in the schematic suggests that the outputs go to anything that would have a different intrinsic tone.

Looking at the schematic for the Mk II indicates that, while the driver circuit had been changed, there was no functional change in what the circuit accomplishes: two anti-phase amplitude variations in otherwise identical audio outputs - an autopanner.

Part of the  beautiful sound of the Rhodes comes from the lilting aspect of that circuit and accompanying cab, and the manner in which it enhances the inherent chimeyness of the Rhodes.  And part of how it does that is a result of the very modest modulation it produces.  This is no Eddie-Kramer-its-over-here-now-its-over-there modulation.  Its a shimmer, and it works just right.

[thedefog]

Okay, that makes sense of the seeming discrepancy between the sound and the schematic.  Nothing in the schematic would suggest anything more than an autopanner, but obviously nothing in the schematic suggests that the outputs go to anything that would have a different intrinsic tone.

Looking at the schematic for the Mk II indicates that, while the driver circuit had been changed, there was no functional change in what the circuit accomplishes: two anti-phase amplitude variations in otherwise identical audio outputs - an autopanner.

Part of the  beautiful sound of the Rhodes comes from the lilting aspect of that circuit and accompanying cab, and the manner in which it enhances the inherent chimeyness of the Rhodes.  And part of how it does that is a result of the very modest modulation it produces.  This is no Eddie-Kramer-its-over-here-now-its-over-there modulation.  Its a shimmer, and it works just right.

And when it is pulled out into the midlle of a room, it sounds like nothing else in this world. Now I'm going to be bugged this whole weekend thinking about designing a circuit to simulate this, and of course I have no free time at all to do it. 

[Solidhex]

 Probably not what you're looking for but I bet it could be interesting and very simple. Build a simple boost or buffer. Send that into a regular Muff tone section splitting it into a high pass and low pass. Then plug that into Deadastronaut's tiny stereo panner but backwards so instead of taking a mono signal and panning it in stereo, it takes the two differently eq'd signals and makes a mono treble/bass tremolo.

--Brad

[Taylor]

Probably not what you're looking for but I bet it could be interesting and very simple. Build a simple boost or buffer. Send that into a regular Muff tone section splitting it into a high pass and low pass. Then plug that into Deadastronaut's tiny stereo panner but backwards so instead of taking a mono signal and panning it in stereo, it takes the two differently eq'd signals and makes a mono treble/bass tremolo.

--Brad

Along those lines, a post from Rick from awhile back:

http://www.diystompboxes.com/smfforum/index.php?topic=80310.0

[thedefog]

Probably not what you're looking for but I bet it could be interesting and very simple. Build a simple boost or buffer. Send that into a regular Muff tone section splitting it into a high pass and low pass. Then plug that into Deadastronaut's tiny stereo panner but backwards so instead of taking a mono signal and panning it in stereo, it takes the two differently eq'd signals and makes a mono treble/bass tremolo.

--Brad

@Solidhex - Awesome! I was thinking that SAME exact thing today. Saw the muff tone thing on Beavis's page, then read almost the entire thread for the Tiny Tremolo today and saw they had a similar idea with low pass/high pass filtering. I guess the trick will be to get the exact rEQ/Blend where it still sounds and feels like the Rhodes. Going to breadboard it as soon as I get the time to do it.

@Taylor - Thanks for the link.

I think I'll start by breadboarding the tiny tremolo because it is easy enough.

[Solidhex]

Probably not what you're looking for but I bet it could be interesting and very simple. Build a simple boost or buffer. Send that into a regular Muff tone section splitting it into a high pass and low pass. Then plug that into Deadastronaut's tiny stereo panner but backwards so instead of taking a mono signal and panning it in stereo, it takes the two differently eq'd signals and makes a mono treble/bass tremolo.

--Brad

@Solidhex - Awesome! I was thinking that SAME exact thing today. Saw the muff tone thing on Beavis's page, then read almost the entire thread for the Tiny Tremolo today and saw they had a similar idea with low pass/high pass filtering. I guess the trick will be to get the exact rEQ/Blend where it still sounds and feels like the Rhodes. Going to breadboard it as soon as I get the time to do it.

@Taylor - Thanks for the link.

I think I'll start by breadboarding the tiny tremolo because it is easy enough.

Whoa, more than along the same lines I'd say haha! I bet adding the "presence control mod" would give you lots of control over the tone of the trem. Another fun thing to try (not sure if it would make much of a difference or do anything cool) would be to use a phase splitter to feed the two hi/lo filters so the two signals fight a little bit in the middle of the sweep.