MicMix MasterRoom XL-305 Spring Reverb Clone

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haima
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Re: MicMix MasterRoom Spring Reverb Project

Post by haima » Fri Jan 08, 2010 8:25 pm

hi all - just wanted to express my interest in the MasterRoom project... i'd love to make something like this one day.

wayne - don't suppose you've had a chance to take your project any further?

this thread came up while we were discussing the AKG BX-20 over at the prodigy-pro forum:

http://www.prodigy-pro.com/diy/index.php?topic=37106.0

thanks - all the best for 2010 everyone!
haima

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mediatechnology
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Re: MicMix MasterRoom Spring Reverb Project

Post by mediatechnology » Sat Jan 09, 2010 7:14 am

The last time I worked on that project I was counting spring turns. Several hundred.

My daughter was pestering the crap out of me that day and I lost count many, many times. That was 2007. I gave up and it sits on my workbench. The first spring's count measured almost exactly right in the time domain. Once the first set are and they can just be measured.

Kids and DIY don't mix if you need to concentrate.

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haima
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Re: MicMix MasterRoom Spring Reverb Project

Post by haima » Sat Jan 09, 2010 7:57 am

that sounds like fun :shock:

i have a HUGE pile of unfinished projects - and i don't even have kids i can blame that on!

selfishly i hope you find some quiet time to concentrate on the count one of these days :D

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mediatechnology
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Re: MicMix MasterRoom Spring Reverb Project

Post by mediatechnology » Sat Jan 09, 2010 10:17 am

Once you get the number of us per turn and the first set cut it's a piece of cake.

They still vary a little bit and if I recall correctly at MicMix we cut them a few turns long and then trimmed them via measurement. I built the box to time them. They'd load up a spring, pulse it, and it would read out in tenths of ms. They'd take a few turns off, re-form a hook, and re-measure. The ladies who did it affectionatley called themselves "hookers."

I think this was due to the variance in diameter that we'd get from Accutronics at the time.

I briefly looked at the post you cited and there are a few tricks AKG did that I recall. I think they chemically etched the springs too. But the real trick in all of this is the timing. It's not magic. What you want to avoid is having all the echos cluster. That creates the boing. Log spacing solves that in the math.

I think anyone wanting to use a MasterRoom on reggae would be disappointed because it doesn't have the twang and fluttery slap-happy feel.

dmlandrum
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Re: MicMix MasterRoom Spring Reverb Project

Post by dmlandrum » Sun Feb 07, 2010 8:30 pm

This is the thread that made me join this board.

I've been obsessed with different ways of creating reverb, from wiring up a piano soundboard with transducers set up in a feedback loop to stringing up a few slinkies and hooking piezo disks at each end to learning how to record my own impulse responses. Sadly, my little basement lab area isn't really able to accommodate a piano soundboard, though the slinkies and IR recording can still be done, I'm sure.

As a physics student (I'm even taking a class on vibrations and waves this semester), figuring out how to measure microseconds per turn on a spring sounds like something right up my alley. It sounds like you already know how to do that, though, so I guess all I can do at this point is collect info and see about building something of my own.

ethervalve
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Re: MicMix MasterRoom Spring Reverb Project

Post by ethervalve » Tue Feb 09, 2010 11:06 am

Hi,
I was also prompted to join the forum because of this thread (though I'm also very interested in the MS Matrix project and compressor projects too).
I just bought a Master Room XL-515 reverb unit and I love it to death! I vastly prefer it over my Demeter RV1 spring reverb (which I've been using an my main vocal reverb).
There doesn't seem to be a thing about this model on the internet. The main control unit is 3ru high and gives 3 reverb choices: plate; room; and hall. There is also a decay knob with an LED readout. The control unit gets connected to the 4ru high (and very deep) 'remote chamber' by an 18 pin connector that looks to like an oversized version of those things that Ampex used to connect the transport to preamp units.
I haven't had time to take pictures, but here are the seller's photos from the classifieds that I bought it off of:

Image

Image

If Wayne or anyone else knows anything about this model, I'd love to hear it.
Thanks in advance.

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mediatechnology
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Re: MicMix MasterRoom Spring Reverb Project

Post by mediatechnology » Wed Feb 10, 2010 7:01 am

Wow. What a nice piece. Thank you for joining us too!

Bob Rodgers was the designer of that one. I believe MicMix produced it after the death of one of the founders, John Saul, when Bob and Bill Allen bought the company. Before I left Bob and I did a lot of work on the decay circuitry with Bob eventualy morphing the decay circuitry into the DynaFex noise reduction unit.

That 18 pin connector is a Cinch-Jones plug also used frequently on MCI transports.

I believe I have a brochure of the unit I can scan and post here. I have no schematics.

For the benefit of people who have never heard a MasterRoom how would you describe its sound? Does it sound like any spring reverb unit you've ever heard?

ethervalve
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Re: MicMix MasterRoom Spring Reverb Project

Post by ethervalve » Wed Feb 10, 2010 1:59 pm

Thanks, I would love to see the brochure! I wonder exactly what the 18 pins are used for?
Kudos on your work on the decay circuitry--I find it works far far better than the 'dwell knob' on any spring reverbs I've tried. Did you use an expander/gate to achieve this?
Hmmm to describe the sound....
Well first I would say that even with the EQ disengaged, the three settings have quite different colours.
I went through all the settings with a number of instruments on the Alan Parsons & Stephen Court Sound Check CD. I was especially surprised and impressed with its performance on percussion. It's perfect for the kind of stuff I do.
I'm going to try to record some samples of dry vs wet and post some links this evening.

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haima
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Re: MicMix MasterRoom Spring Reverb Project

Post by haima » Thu Feb 11, 2010 1:37 am

ethervalve - that's a nice piece you've got there! i'd love to hear some samples!

i wonder how different this unit is to the earlier ones...? internal pics?!

cheers,
haima

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mediatechnology
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Re: MicMix MasterRoom Spring Reverb Project

Post by mediatechnology » Thu Feb 11, 2010 12:43 pm

Here's a pdf for the XL-500 Master Room that I stitched together:

http://www.proaudiodesignforum.com/Imag ... _XL500.pdf
Kudos on your work on the decay circuitry--I find it works far far better than the 'dwell knob' on any spring reverbs I've tried. Did you use an expander/gate to achieve this?
Thanks. I'm not sure what Bob ended up using but it is a compressor/expander. Most of my work on the decay involved RMS detection and a non-linear capacitor and/or sample and hold-based NLC. Like the Pico Comp.
I was especially surprised and impressed with its performance on percussion.
We often used rim-shots as demos to illustrate how the Master Room didn't "boing" vs. the AKG and Orban units. We also used a "pulser" to act as a rim shot. The key to the smoothness are the log-based (equally-tempered) first-order echo timings.
I'm going to try to record some samples of dry vs wet and post some links this evening.
That would be awesome to hear on music samples. If you could also synthesize a click (or use a click track) with the click in the R channel and the echos on the L that would be cool. Leave several seconds between clicks. I'd like to dissect the first 100 ms of echos in a wav file and display the pic. (If you need me to host the files I'll be glad too. You'll get a lot of hits and consume BW. PM me and you can e-mail them to me. I suppose the music sample could be mp3.)

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