Author Topic: Peterson Preamp--ho, hum  (Read 5225 times)

Offline pnoboy

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Peterson Preamp--ho, hum
« on: September 30, 2015, 07:03:00 AM »
For reasons I don't understand, the Peterson Preamp, as used in older suitcase Rhodes, is often highly regarded.  My first Rhodes was a suitcase 73 with the Peterson circuitry and I did not find its tone desirable--if fact, it had a somewhat dull, muffled sound.  I ended up selling the suitcase Rhodes and getting a stage model, because I found that the Rhodes sounded better with many guitar amps than it did with its own suitcase amp.  Also, gigging with the Rhodes was bad enough, carrying around the large suitcase amp was the final insult.

To see if there was anything special about the Peterson circuitry in terms of its equalization, I simulated it in SPICE.  The graph is of its frequency response with the tone controls centered.   We can see that there's nothing special--its response is pretty flat, with a treble rolloff that may, in part, contribute to its somewhat dull sound.  The tone controls are standard Baxandall, centered around 500 Hz, which is common in guitar amps.  If anything, the slight bump in response in the 100 to 300 Hz range is exactly what a Rhodes doesn't need, though the bump is small enough that it's probably not particularly noticeable.

I'm also not a fan of the stereo tremolo as implemented.  First of all, the speakers in the suitcase camp are too close together to give a true stereo effect--especially in a performance situation in which the audience is much further away from the Rhodes than the spacing between its speakers.  If in the studio, then the preamp's 2 output channels, if fed to the mixing board separately, could create a true stereo effect.  However, my biggest gripe about the tremolo is its lack of smoothness.  The tremolo oscillator is a multivibrator, which creates an abrupt rather than smooth transition from speaker to speaker.  This lack of smoothness is readily heard, and not at all pleasant to me.
« Last Edit: September 30, 2015, 10:35:22 AM by pnoboy »

Offline Ben Bove

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Re: Peterson Preamp--ho, hum
« Reply #1 on: September 30, 2015, 01:11:47 PM »
Interesting assessment.  What I will say, is that most times I've seen people play a Peterson it's with the treble knob all the way up.  You may want to have a look at the response on that graphically.

The "highly regarded" may come as a comparison only to the 5-pin Rhodes model, where people are only comparing these 2 suitcase amp systems.  People seem to prefer the smoother vibrato on a Peterson due to the on-off times with the preamp lightbulbs rather than the on/off sharpness of the vibrato on a Janus.  The treble EQ on the Janus I also feel grabs the wrong register and is too high, so people tend to prefer the EQ on the Peterson (again in comparison with these two amps).

Playing a stage Rhodes through a twin reverb is definitely a different experience - reverb alone is a missing effect on the suitcase, plus you get bass / MID / Treble which gives you more of an EQ option.  Then of course, the volume is extremely different on a twin.  The only thing missing is the vibrato that comes with a suitcase, so people tend to stick with a suitcase model for that reason because it's a signature effect.  So you may not consider the peterson as the "1967 Corvette 427" of the Rhodes world, but appears to get the majority of preference between suitcase models.

Just a few things to consider, and definitely check out a Peterson with the treble up.
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Offline pnoboy

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Re: Peterson Preamp--ho, hum
« Reply #2 on: September 30, 2015, 02:32:34 PM »
Thanks for your thoughtful reply.  When I had my suitcase, I too played with the treble all the way up, but that still didn't get the sound I wanted.  The problem I found with that is that it made the treble notes sound too loud, and so one had to back the pickups away from the tines, but with the pickups backed away, very few harmonics were produced, yielding a dull sound.  So, it was a kind of vicious circle.

When I had my stage piano, I ended up designing a preamp with an equalizer.  What I found was what the Dyno-My-Piano people found--Rhodes pianos often sound best with a pretty flat response, but with a dip around 300 Hz or so.  When you think about it, that's not too different from what Fender does with their guitar amps.  With their tone controls centered, they have a large dip at 500 Hz.  Here's a fun little program that demonstrates the tone-control action on quite a few of the well-known guitar amps http://www.duncanamps.com/tsc/download.html.

I am currently restoring a 1978 stage piano--when I'm done, I'm thinking of designing a preamp with a very smooth mono tremolo.  Most tremolo circuits are pretty sleazy and are designied for minimum cost rather than excellent performance.

Offline Student Rhodes

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Re: Peterson Preamp--ho, hum
« Reply #3 on: October 01, 2015, 12:16:12 AM »
However, my biggest gripe about the tremolo is its lack of smoothness.  The tremolo oscillator is a multivibrator, which creates an abrupt rather than smooth transition from speaker to speaker.  This lack of smoothness is readily heard, and not at all peasant to me.
Try turning your "Depth" down.  The pan becomes a little more centered and takes away some of the hard right/hard left, so you get more of a smooth shimmer, rather than an alternating on/off in each ear.  As heard in one of my all time favorite Rhodes clips from youtube

https://www.youtube.com/watch?v=RD1nBPRZc-I

If you can't appreciate that, then the Peterson is definitely not for you.

I also think greater appreciation can be had when you consider the Peterson trem in the context of 1969, when it came out.  Before that, Rhodes used the the mono Jordan system, (which itself was a great leap over not having any vibrato at all). But it was mono.  The Peterson was a difference on the order of going from 2-D, to 3-D.   Which is why so many thousands of recordings were made using it.  It is a signature sound of the Rhodes.  Yes, the stereo spread is lost in an unmic'd live situation -- as it is with any unmic'd guitar amp from twenty feet away. 

To borrow Ben's metaphor, even a 427 Stingray gets blown away by the power performance and handling of any contemporary sports car.  But if you want the feel and sound of that Vette, only the real thing is the "real thing." 

I also have a stereo trem pedal, which on paper is "superior" to the Peterson.  More wave forms, tap capability, consistent tempo, blah, blah, blah.  It also requires a power supply, three cables, two amps...  For my money, if I want to just sit down and enjoy playing and hearing a Rhodes with stereo tremelo, the simplicity and self containment of the Peterson can't be beat.   

As I've stated in other posts, I'd still love to hear mods to the circuit to take some of the flatness out if it.  Perhaps some component value swaps do the trick for you.

Offline Tim Hodges

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Re: Peterson Preamp--ho, hum
« Reply #4 on: October 01, 2015, 06:27:10 AM »
First of all, the speakers in the suitcase camp are too close together to give a true stereo effect--especially in a performance situation in which the audience is much further away from the Rhodes than the spacing between its speakers.

The super satellite setup is a good alternative. At least that way you have the Peterson and the pair of 2 x 12 speakers set apart. To me this is the smoothest sound you can get (7:40 in Eumir Deodato's Moonlight Serenade)

https://youtu.be/Rk3F6r5VUzY?t=7m40s

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Offline pnoboy

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Re: Peterson Preamp--ho, hum
« Reply #5 on: October 01, 2015, 07:00:58 AM »
There have been many interesting ideas brought up, and I'll try to address a few of them.  1969 wasn't the dark ages, and, for example, the Fender tone controls, which have a midrange dip, came out in the 50s.  All the technology and knowledge to allow the Peterson preamp to have some alternative equalization was available in the 60s. 

Of course it's true that turning the tremolo depth down makes it sound less harsh, but, to me, that's a bit like saying that the less of it you use, the less you notice its poor quality. 

As to the Deodato link, that tremolo sound epitomizes what I don't like about the Peterson tremolo.  To my ear, it has a ping-pong quality, where the sound switches from left to right rather than moves smoothly from left to right.  I think that if we all could hear a Rhodes through a good quality, smooth panner, the Peterson tremolo would sound pretty deficient by comparison. ...just IMO.

Offline Ben Bove

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Re: Peterson Preamp--ho, hum
« Reply #6 on: October 01, 2015, 01:55:09 PM »
If you're looking for a more smooth tremolo "Vibrato" effect, that's also got more midrange punch and EQ options, I'd really try to hunt down a full Dyno rail, with the Dyno preamp and the tri-stereo tremolo unit.  What is unique about how they modeled their tremolo, is the wave selection knob.  You can go from harsh square wave to very smooth triangle wave, and it definitely gives you the options of what I think you're looking for with the triangle wave tremolo plus a more responsive EQ.  I have an audio sample somewhere just demoing the tremolo, I'll see if I can dig it up.
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Offline Ben Bove

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Re: Peterson Preamp--ho, hum
« Reply #7 on: October 01, 2015, 02:10:37 PM »
Chords demoing the different tri-stereo tremolo settings - triangle wave, sine wave, square wave.  Intensity and speed differences... you'll want to use a pair of stereo headphones to get the full effect.

https://soundcloud.com/bjammerz-933737275/dyno-vibrato-test

Some photos that will give you an up close look at the rail controls:
http://retrorentals.net/product/fender-rhodes-dyno-my-piano/
« Last Edit: October 01, 2015, 02:13:02 PM by bjammerz »
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Offline Student Rhodes

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Re: Peterson Preamp--ho, hum
« Reply #8 on: October 01, 2015, 05:17:49 PM »
1969 wasn't the dark ages, and, for example, the Fender tone controls, which have a midrange dip, came out in the 50s.  All the technology and knowledge to allow the Peterson preamp to have some alternative equalization was available in the 60s. 

No, 1969 wasn't the dark ages for electronics.  Many believe by this point Man had walked on the moon.  But in terms of adoption of the electro mechanical piano in popular music, it's about as close to the dark ages as you come.  As with the evolution of guitar pedals, it's usually not until someone invents the effect that there evolves a musical "need" or creative use for it.  So in terms of use, in '69, the Peterson was in a way, cutting edge. 

Of course it's true that turning the tremolo depth down makes it sound less harsh, but, to me, that's a bit like saying that the less of it you use, the less you notice its poor quality.

I don't think your characterization is quite correct.  Using the depth knob does more than diminish the amount of, or volume of the effect.  If you put on headphones, you can clearly hear the knob changes the placement of the stereo signal from thee o'clock and nine o'clock on a clock face, to a still very pleasant and smoother orientation of say, eleven o'clock and one o'clock, or even narrower.   It sounds like you're seeking something that has more of a, for lack of a better metaphor, "pendulum" type shift between left and right. 

It's clear you're not a fan of the Peterson.  However, you can always find a pedal or signal path to create what it is you're looking for.  In the mean time, the Rhodes/Peterson sound "is what it is".  It too would have been nice if the Model T had come with airbags and ABS brakes.  But it didn't.   
 

« Last Edit: October 01, 2015, 05:55:03 PM by Student Rhodes »

Offline Tim Hodges

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Re: Peterson Preamp--ho, hum
« Reply #9 on: October 02, 2015, 05:14:19 AM »
This has been an interesting thread to read and it's good to see the range of opinions.

To me the ping pong of the vibrato is excellent, it's what it's known for and I like it. Yes it could be smoother (arguably by today's standards) but with the previous point about Model T's in mind, when it was released it was for an E.P. which I would consider not a massively popular product (until much later) so in terms of manufacturing they may have been able to make a better design(?) with better components but then you've got to deal with the cost implications of manufacturing such a device and was it going to be worth it?

I guess something comparable would be the B3 and the key click on the keys, it was a design flaw which Hammond hated but people loved it and wanted it:

Quote
The mechanical key contacts on the B3 have audio level signals present on them. Switching these directly through to the output caused audible clicks. These clicks have become a signature part of the Hammond sound. The clicking is caused by a combination of the nine key contacts not shutting simultaneously, and contact bounce exacerbated by dirty contacts. This causes a random rapid switching of the signal in the initial portion of the note. Since this switching introduces transients, we hear this as a sound with much random high frequency content – a click. This could be simulated either by adding in transient noise, or by electronically simulating contact bounce.

They eventually fixed it and removed the click but took away what made it unique even though on paper a silent key was the best thing.
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Offline laberge

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Re: Peterson Preamp--ho, hum
« Reply #10 on: October 02, 2015, 04:48:18 PM »
Chords demoing the different tri-stereo tremolo settings - triangle wave, sine wave, square wave.  Intensity and speed differences... you'll want to use a pair of stereo headphones to get the full effect.

https://soundcloud.com/bjammerz-933737275/dyno-vibrato-test

Some photos that will give you an up close look at the rail controls:
http://retrorentals.net/product/fender-rhodes-dyno-my-piano/

Welp. looks like I need to start over and buy myself a dyno rhodes. That sounds magnificent!

Edit: As someone with a Peterson pre, I kind of agree with your assessment on the Vibrato itself but I like the "chunkyness" of the pan so its not a bad thing. Not sure that I agree with the treble sound though, I quite like the way mine sounds.
« Last Edit: October 02, 2015, 04:50:00 PM by laberge »

Offline pnoboy

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Re: Peterson Preamp--ho, hum
« Reply #11 on: October 03, 2015, 12:45:48 PM »
Chords demoing the different tri-stereo tremolo settings - triangle wave, sine wave, square wave.  Intensity and speed differences... you'll want to use a pair of stereo headphones to get the full effect.

https://soundcloud.com/bjammerz-933737275/dyno-vibrato-test

Some photos that will give you an up close look at the rail controls:
http://retrorentals.net/product/fender-rhodes-dyno-my-piano/

Nice sounds--thanks for posting.

Offline JanneI

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Re: Peterson Preamp--ho, hum
« Reply #12 on: October 03, 2015, 01:43:55 PM »
I made a proto of the dyno-my-piano preamp based on a schematic found on the forums. The eq curve is quite different compared to the peterson, but the output signal level is very very low. Here's a video, this rhodes is a mk2 5280:

https://www.youtube.com/watch?v=Cf-HroHJsQo

I've also used the BBE Sonic Stomp pedal with Vintage Vibe stereo vibe preamp on my Rhodes 54.

Just sharing these for comparision. It's still a work-in-progress. :)

Offline laberge

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Re: Peterson Preamp--ho, hum
« Reply #13 on: October 05, 2015, 11:29:14 AM »
I made a proto of the dyno-my-piano preamp based on a schematic found on the forums. The eq curve is quite different compared to the peterson, but the output signal level is very very low. Here's a video, this rhodes is a mk2 5280:

https://www.youtube.com/watch?v=Cf-HroHJsQo

I've also used the BBE Sonic Stomp pedal with Vintage Vibe stereo vibe preamp on my Rhodes 54.

Just sharing these for comparision. It's still a work-in-progress. :)

Hey! This sounds like a really cool project.

Can you post the schematic?

Offline tomogradymusic

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Re: Peterson Preamp--ho, hum
« Reply #14 on: October 05, 2015, 05:42:22 PM »
This is a very subjective matter, even if there is an attempt to examine it objectively and look at the technology behind the various amp designs. It's a bit like people preferring the tone of Chick's mkV to Herbie's mk1 or a dyno-Rhodes. Each to their own and all that.
This talk of stereo spread lacking in live conditions is unnecessary; I use my suitcase for every gig - I use the direct outs panned hard left and right - beautiful suitcase Rhodes tone bouncing from one side of the venue to the other.
It's an interesting topic to have brought up but it's fairly obvious that nobody will change the original poster's opinion - and neither will they change mine. Suitcase Rhodes with a Peterson amp/preamp for me .. and I don't even use it with the treble turned up.
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Offline JanneI

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Re: Peterson Preamp--ho, hum
« Reply #15 on: October 06, 2015, 01:09:05 AM »
That dyno-my-piano proto was based on this one:

http://www.lynx.net/~jc/DMP900components-Schem.jpg


And yes, it's impossible to determine which is "the best rhodes preamp", it's a matter of personal preference. Instead we could provide info/audio on different type of preamps and that way we all could benefit on the journey to find the best rhodes sound for ourselves.

Offline goldphinga

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Re: Peterson Preamp--ho, hum
« Reply #16 on: October 06, 2015, 08:20:00 AM »
I've extensively used all the preamps. To my ears the pre's i like the most are the Peterson design I have on my 1972 suitcase and the low noise late mk2 preamp I have installed as a retrofit on my 1980 MK2. I also have an original black face slider preamp that was in my 1980 rhodes as part of a janus speaker system but it has a couple of mods on that have messed with the tone that im going to get reversed. Those pre's sound good too.

They all sound great in their own right and each preamp goes perfectly with each era of piano to my ears. My biggest surprise was how beautiful that late mk2 preamp is, it has the peterson mojo, real high quality and even quieter too with much nicer eq- actually i'd say this is my fave. Think they're quite rare and often overlooked. Only thing is i wished the trem went a bit faster but it sounds dope.