Anyone interestd in clones of R.A. Moog Bode 6402 or 6552?

Anything modular synth related that is not format specific.

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mike.synthesizer
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Anyone interestd in clones of R.A. Moog Bode 6402 or 6552?

Post by mike.synthesizer » Sun Jan 25, 2015 8:51 pm

I've got access to these two bad boys right here and it doesn't seem extremely difficult. Thoughts?

http://borishelectronics.com/MoogModular/Bode/

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Post by nbirnel » Sun Jan 25, 2015 9:03 pm

Why yes, I would be interested in a Bode-style frequency shifter, especially in euro.

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Post by sduck » Sun Jan 25, 2015 11:14 pm

I don't think that's going to fit into a handy euro style module.

The Analogue Systems RS240 is probably what you're looking for in euro land.

To the OP - yea, go for it! If you could clone the 5U/MU version, you'd certainly sell them by the dozens. I don't know about those rack mounted versions.
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Post by fluxmonkey » Mon Jan 26, 2015 9:06 am

transformers may not be that easy to source...

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Post by kindredlost » Mon Jan 26, 2015 12:01 pm

I tend to agree with sduck (stranger things have happened). A MOTM or even better, a dotcom Moog/Bode clone would be the fleas knees.
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Post by calaveras » Mon Jan 26, 2015 1:45 pm

It could fit in Euro, it would just take up a ton of HP. I also wonder what the power requirements would be? I'm no EE, more of an electronics hack, but IME transformer based stuff tends to be kind of a current suck. Just look at the power supply on the right side of the picture. That looks like several amps of current right there.
Might need to be re-worked to live within eurorack volts/amps constraints?

I'd love to know what the transformer's ratios are. And what the two octal chips are. I'm guessing they aren't op-amps just by the numbers of plain old three leggers that are adjacent.

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Post by daverj » Mon Jan 26, 2015 1:49 pm

Be aware that having one of Bode's frequency shifters, and making a duplicate aren't necessarily a straight line from one to the other.

Harald used to spend a lot of time hand selecting the components used in the dome filters. Hours and hours. Plus every couple of units he would change his mind about the core values for those filters, changing and tweaking the design as it went along during those years.

So any given unit of his frequency shifter is really a snapshot of that moment in time in the slow and ever changing evolution of that device.

Also be aware that the version you have is the early model that Bode made for Moog when they were still in Trumansburg. The model that was in a regular Moog Module format was a later variation with more features, built when Harald was chief engineer at Moog Music, after Bob had quit.

COTK (theoretically) licensed that later version and sells them in 5U, but as far as I understand he's never actually sent Harald's heir a royalty payment.

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Post by mike.synthesizer » Mon Jan 26, 2015 10:23 pm

Thanks for the responses guys.

I understand that I might need to do some hand matching with a curve tracer or something. I also understand that transformers might not be easy to source. Regardless, there's just not many components on there.

My guess is that the two octal chips are prehistoric operational amplifiers set up for summing.

Regarding the power supply, it is a design ahead of its time. I can't think of too many things that had a precision series voltage regulator in 1968. It is a unipolar design that's probably putting out around 30 or so volts at 2 or 3 watts. I'm judging the wattage by the heat sink size.

The transformers are interstage transformers for transistor applications. The company that manufactured them is UTC. Most of them are A-22's. A-22's have a 500 ohm 1:1 ratio. or you can tap a side in half for 4:1 or 500:125. Also, these little transformers are heavy so mounting options might be limited. They probably weigh at least a pound each!

What makes this project interesting to me is the unique isolation properties of the transformers.
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Post by calaveras » Tue Jan 27, 2015 1:24 am

1:1 interstage that are that big?
I'm thinking they must have some crazy low end response or high current/voltage capability? (or both)
is that screw turn adjuster the precision voltage regulator?

It shouldn't be too hard to source decent matching transformers.(of course nothing like vintage UTC) I've got a ton of 1:1 line level output trannies that are similar size and shape, pulled from old Yamaha mixers. I've mostly been using them to add balanced outputs to things. Though I do think I recall Yamaha also used them to sum submasters.
(transformer inputs, submasters and outputs=heavy consoles)

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Post by BugBrand » Tue Jan 27, 2015 6:16 am

I'd suggest examining WHAT is happening in such a circuit and then figuring how much easier it could be today..

Having a brief scan of a Bode Freq-Shift service manual..

Dome Filter board - lots of trimming there. You can calculate values and use precision resistors & caps. (CGS have one based on Electronotes)

Variable oscillators - not sure what squelch is exactly but.. Basically you want pure quadrature sine/cos.

Multipliers - the docs have Motorola 796 multipliers -- never heard of those before.. I'd suggest AD633 these days.


Electronotes is def. good for further reading on Freq. Shifts.


Edit - weird - must be looking at some different bode doc 'cos there didn't appear to be trafos.. And there appear to be 4 cards - Dome, VariOsc, Fixed Osc, Multipliers..
Well, my thoughts still remain the same -- I guess some may want to make a 100% replica (difficult! and soooo much trimming) but with some examination/understanding/careful-changes, you could surely make something the 'same' but easier to make these days.

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Post by paults » Tue Jan 27, 2015 8:27 am

What a modern frequency shifter, with zero carrier feedthrough, multiple carrier waves and fits in 14HP of Euro might look like.

Image

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Post by daluxer » Tue Jan 27, 2015 10:41 am

jual kursi makan yang menggunakan bahan kayu jati dan mahogani berkualitas baik dengan harga yang relatif terjangkau dan murah sesuai dengan apa yang kami berikan, kualitas kayu perhutani, desain mebel yang elegan, kontruksi dan kehalusan finishing yang khas dari kami.
I gotta say, I totally agree with what you said! Finishing yang khas dari kami!

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Post by sduck » Tue Jan 27, 2015 11:48 am

I have Paults's fs, and it's an excellent device.

It would be worth investigating Jurgen Haibles FS1a design http://www.jhaible.com/fs1a/fs1a.html - it's an outstanding sounding fully analog fs.

When I'm not posting from my phone I'll post some demo vids I've done of these.

Here:

A old, bad demo of the JH FS1a - I didn't really know how to edit videos back then, and added all the commentary via youtube annotations, hence, they don't work on ipads or iphones or anything that flash doesn't work on -

[video][/video]

A slightly newer comparison of the FS1a and the Synthesis Technology e560 Deflector Shield -

[video][/video]
Last edited by sduck on Tue Jan 27, 2015 3:44 pm, edited 1 time in total.
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Post by calaveras » Tue Jan 27, 2015 12:50 pm

paults wrote:What a modern frequency shifter, with zero carrier feedthrough, multiple carrier waves and fits in 14HP of Euro might look like.

Image
and is digital.
'The e560 is a triple-mode effects module: thru-zero frequency shifter, phaser and ring mod. what sets the e560 apart from other dsp effect modules is the unique carrier wave morphing feature. The e560 is another unique dsp-based module that has no equal in the modular world, in any format. if you are 'stuck in a musical rut' and are looking
for a new module with a wide range of sounds, the e560 might be what you are looking for.'

Which is all fine and good but some folks want an analog equivalent.

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Post by CZ Rider » Tue Jan 27, 2015 7:44 pm

I would be interested in cloning the Bode discrete frequency shifter if I had the schematics.
The Bob Moog Foundation recently posted the schematic to the 6401/6402 Bode ring modulator. From what I have read the Bode 6552 has a similar pair of ring circuits for the core of the frequency shifter.
Image
Not to be confused with the later Bode 1630 frequency shifter, the 6552 is all discrete circuits using those UTC transformers. There must be an R.A.Moog schematic for the 6552 somewhere? Anyone?
I did build a Bode type ring module for an R.A.Moog system using discrete components and Edcor audio transformers. Did not need all the extras the 6401 has as a stand alone module, just the basic core.
Image
Sounds great and unlike any modern ring modulator. Something about sending a signal through all those miles of wire wound on an iron core sounds pleasing. I would bet while the Bode 6552 may not have the specs of a modern frequency shifter, it probably had an amazing and unique tone.

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Post by calaveras » Tue Jan 27, 2015 8:16 pm

CZ Rider wrote: Image
Nice job!
who needs a PCB?

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Post by CZ Rider » Tue Jan 27, 2015 8:34 pm

The old Vectorbord construction was used by both Harold Bode and Bob Moog on quite a few of those early designs.
Here is a 6552 using the same construction.
Image

I really enjoy using that old method of T-28 pins with .062" hole Vectorbord. Easy to change and hot-rod circuits.

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Post by calaveras » Tue Jan 27, 2015 11:04 pm

I did some Craig Anderton circuits like that back in the late eighties or early 90's. It took me forever because I was much worse at soldering back then. Simple stuff like fuzz boxes and a compressor. I honestly thought I was going to build a freaking studio like that...

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Post by mike.synthesizer » Tue Jan 27, 2015 11:30 pm

Thanks a lot. I didn't know that schematic was available. It doesn't look too difficult. Your module looks great with the transformers on the bottom there.

I still haven't checked this out yet but it might have some clues:

http://www.aes.org/e-lib/browse.cfm?elib=2059
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Post by Savage » Wed Jan 28, 2015 5:03 pm

It's not the older rackmount version, but if you check out pp. 44-46 of the Technical Service Manual for Moog Modular Systems found here...

http://experimentalistsanonymous.com/di ... 5%2055.pdf

there are schematics for the three cards of the Moog 1630 Bode Frequency Shifter. I searched for schematics to the Bode Frequency Shifter, and the 1630 is about all I could find. I hope this helps out with the project.

Also, in my search I found this issue of dB Magazine,

http://www.americanradiohistory.com/Arc ... 976-03.pdf

and on page 32, there is an article, "Frequency Shifters for Professionals", written by the man himself, Harald Bode, and he often uses the 735 and 1630 as examples in his discussion. Perhaps this may be useful, as well.
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Post by paults » Wed Jan 28, 2015 7:40 pm

Which is all fine and good but some folks want an analog equivalent.
Why?

It's not a troll: do "some people" want an analog reverb, too? How about toss out your laser printer, and use an all-analog Roland X-Y plotter instead?

Analog is not automatically 'better'. Some things are BETTER in digital.

A FreqShifter is such a thing.

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Post by calaveras » Wed Jan 28, 2015 8:06 pm

paults wrote:
Which is all fine and good but some folks want an analog equivalent.
Why?

It's not a troll: do "some people" want an analog reverb, too? How about toss out your laser printer, and use an all-analog Roland X-Y plotter instead?

Analog is not automatically 'better'. Some things are BETTER in digital.

A FreqShifter is such a thing.
I own both analog and digital reverbs. In certain ways they both have strengths and weaknesses. I'm not some 'analog only' purist. I don't think any of my recordings have zero virtual instruments or no digital anything. But in some domains, analog equivalents have a tone or behavior that the digital iteration does not.
If I want perfect pitch shifting I'll do it in my DAW, or I'll use an eventide.

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Post by Neo » Thu Jan 29, 2015 7:44 am

paults wrote:
Which is all fine and good but some folks want an analog equivalent.
Why?

It's not a troll: do "some people" want an analog reverb, too? How about toss out your laser printer, and use an all-analog Roland X-Y plotter instead?

Analog is not automatically 'better'. Some things are BETTER in digital.

A FreqShifter is such a thing.
Because sometimes analog sounds better. Why go 5U when you could use plugins? :wink:
I could be wrong but I thought there were some moments in the fs comparison where the FS1A had a tiny bit more magic than the E560, especially in the phasey sounds. But I have an E560 and I love it :tu:

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Post by BugBrand » Thu Jan 29, 2015 7:52 am

paults wrote:Why?

It's not a troll: do "some people" want an analog reverb, too? How about toss out your laser printer, and use an all-analog Roland X-Y plotter instead?

Analog is not automatically 'better'. Some things are BETTER in digital.

A FreqShifter is such a thing.
Is input clipping one of those digital betters?!
(sorry, low joke!)

But, yes, people do want analogue sometimes (def. on reverb).

Life is not always as logical as engineers may believe..

(And that is definitely NOT to say that digital can't be wonderful & useful too - but better?! Don't be ridiculous. 'Different' may be more apt. And, yeah, all the precise fine-tuning of an analogue design is surely something of a ball-ache)

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Post by paults » Thu Jan 29, 2015 9:14 am

The only analog reverb, besides recording in a church or grain silo or the hallway, was the EMT Plate type. And they didn't sound all that great.

And there are things plug-ins that no analog thing could ever dream of doing.

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