Meta, recording, Rock History

Euphonic Studio acquires Steve Vai’s early mixer

A Piece of Fusion/Rock Music History

Steve Vai's CMC 24

Steve Vai's CMC 24, or so it is purported to be. If it is, cool. If not, meh.

Euphonic Studio now owns the Allen, Heath & Brenell CMC 24 mixer and accessories purported to have been originally owned by Steve Vai. This, of course, if true, does not affect anything about it other than the fact that it has a connection to one of the top living guitarists on the planet. (And consummate gentleman, artist, scholar, and Renaissance man).

I should QUICKLY add that I have not yet received confirmation of this from Steve Vai himself; I am going by the word of the seller who tells a convincing story of having purchased the mixer and a Fostex 16 track tape deck from Steve Vai. Steve Vai indeed did own a Fostex 16. I have obtained samples of Steve’s handwriting from the ‘net and compared it to notes in the manual; I am not a graphoanalyist but I can say that there is enough similarity to not rule it out.

So we wait.

Allen and Heath traffic jam

Allen and Heath traffic jam? No, just a groovy sort of reunion between two somewhat rare pieces of history

As some of my customers know, I use a CMC24 for analog summing, the last step before mixdown to stereo. This mixer allows me to take 24 outs from my digital system, mix them in the analog world,  and then send them back to 2 digital inputs to record the mix onto a stereo track. This method is alternate to mixing the digital signals from 24 tracks (or more) “inside the box”, meaning everything is done within the computer’s software tools to mix down to a stereo track.

The topic of analog summing is one that gets people’s dander up. My personal experience is that I can clearly hear a difference and the difference is that analog summing provides improved stereo image, greater depth, more clarity across the whole frequency spectrum, and in short, a much more professional sound. The person who talked me into trying this is the author of Zen and the Art of Mixing which is, as far as I’m concerned, the most authoritative book on mixing that I’ve read. The author, BTW, goes by the name “Mixerman” and if you are in the mixing business and haven’t read this book then I have a distinct advantage over you. That is, unless you have 30 years of experience in the world’s best recording studios and can remember what is pertinent to getting the best mix on each different system you encounter.

CMC 24 Meter Bridge

CMC 24 Meter Bridge - these are nearly impossible to find, so I had a lucky day!

Getting back to the mixer for a moment… the reason I purchased this mixer actually had nothing to do with being a star-struck Vai fanatic (although if you watch this video and don’t end up being at least a jaw-dropping admirer then I’d say maybe there’s something not quite right with your hearing) but actually had to do with the fact that it has a meter bridge and a CMI interface to a COMMODORE 64 COMPUTER! That’s right… you can run this mixer from a Commodore! LOL! I can’t use that in my studio at the moment but I am looking for a Commodore to test it and may sell the CMI interface on eBay to someone who really, really wants it. A&H add-ons for this mixer are very difficult to find. My meter bridge is serial number 005. Since it cost almost $600 in 1988, not too many meter bridges were made. So… the cost of the mixer was worth the cost of the meter bridge, plus I got a spare power supply, a backup mixer, and the Commodore interface. Oh, and it might just have come from Steve Vai’s studio.

CMI interface

CMI interface for connecting the CMC24 to a Commodore computer. This allows you to change signal routing and muting along with the track's time code if you want to demonstrate early automation to propeller-capped pocket-protector types.

Now let me just clarify one thing about the possible Steve Vai connection. This has a lot of meaning to me on some level, but that has NOTHING to do with implying that you are going to sound like Steve Vai if you record here. NO, NO, NO. The way you get to sound like Steve Vai is to practice guitar for 10 hours a day for weeks or months or years on end. That’s how HE did it. Unless you are some kind of savant, you will need to put in the time, too.  And it’s not just TIME… it’s a special form of intellectual discipline that keeps you focused and curious about sound the entire time you are playing.

One last word. You do not have to play at the level of Steve Vai to record good music. You record good music by playing and singing what you know and that has to have a connection with your heart. If your performance comes from the heart, it will be good on some level. After all, music is one way we use to communicate with each other. It is very disappointing to hear a player who does great work but plays very mechanically and carelessly. There’s no communication there; it’s more like being talked down to. Play from your heart with an open heart and you will make great music, whether you have Steve Vai’s chops and mixer or an old cassette deck.


  1. Hi there.
    It seems you’re the foremost expert on the CMC24 🙂

    I was just given one without a power supply. Can’t seem to find one anywhere. Not even sure where to start. Can you tell me the pin voltages?

    You mentioned having an extra one….I’m sure you want to hold on to it…but if not let me know 🙂

    • Hi, Gabe,

      The power supply is nothing fancy, it’s just a linear power supply with the following voltages on the five pin XLR connector:

      Pin 1 -15VDC
      Pin 2 & 3 – ground (zero volts)
      Pin 4 +15VDC
      Pin 5 +48 VDC

      When my original copy of the power supply failed, I happened to have the schematics for the board and back in the mid 80s I took a course on DC power supplies, so I figured WTH, I might as well give it a try. Once I had an oscilloscope, it was very easy to troubleshoot and I think you could build one fairly easily, too. I will email you the schematic at the email address you gave when you posted. I hope it helps.

      One thing I would do if I were designing this is to ditch the T-220 plastic case that are rated for about 1.5A and put in the T-03 case ones that are about twice as much power. If you don’t need phantom power you can do away with the 48VDC part of the circuit, so if you have preamps or are using this for some app that uses dynamic mics only, then you can simplify the build. I am just taking a wild guess at the parts cost, but without the case you can probably build this for around $100 or less. Make sure the voltage regulators are well heat-sinked.

      I would love to help you out by selling my spare but I have a critical application (customers who have a delivery date in mind) so I can’t let it go.

      Thanks for writing, and look for the schematic in your email. It might end up in your spam folder. Please feel free to write if you have any questions about the schematic. Unfortunately, I spent hours staring at it to jog my memory. 🙂

      Good luck and best regards,

  2. Is there any way you could you e-mail me the schematic for the power supply?
    I just picked up a CMC 32 channel board,It’s super clean and looks like new but there was no power supply? I’m having trouble finding help from the techs in my area.
    Any help is appreciated.
    Cheers, Chad

    • Hi, Chad,

      Sending you the CMC24 power supply schematic.

      I feel that the component selection for the voltage regulators is marginal for the CMC24 so I would recommend upgrading them from the TO-220 to the TO-3 case. The unit tends to run hot, and I have already had to replace voltage regulators in the unit.

      Note that if you are not going to use phantom power you can do away with the 48 volt circuit.

      Good luck,


  3. Dylan

    Hey Bill,

    I have a cmc32 (unfortunately without a meter bridge), and I’m wondering how you connect to the mixer – I need to invest in db25->RCA or db25->1/4″, and I can’t decide wether I should use the tape ins, or the line ins. What are your thoughts?


    • Hi, Dylan,

      The analog outs on my ADAT cards are all 1/4″. I bought 3 snakes that are 1/4″ to RCA and use the 16 “multitrack” inputs for inputs. The other 8 RCA inputs are used for effects returns.

      When I got the mixer and started interfacing it with my first iteration of digital (4 DirectPro 24/96 cards) I did use the 1/4″ line ins. They seem to work about the same. One advantage of using the RCA inputs is that you don’t have a forest of wires hanging out of the front of your mixer. Also, it makes it easier to get to the channel inserts which are located right next to the line ins, should you decide to use them. I have a few outboard compressors that I will put into the channel circuits from time to time when necessary.

      Please feel free to email me if you have any other questions or need schematics. Email is

      Good luck and have fun!

  4. Doug Knauff

    I own a CMC32 whose -15 Volt feed from the power supply is not working. Could you please send me the PS schematic, as mentioned in some of the other posts? Also, any recommendations for upgrading the power regulators. I am concerned that I might damage the other regulators when disassembling the power supply, since all 3 regulators are attached to the large vertical heat sink’

    Thanks for your site and help.

    • Hi, Doug,

      I will try to scare up the drawings and send them to the email you provided.

      Keep in mind the schematic I have is for the CMC24… It’s likely to be the same but might not be. The upgrade I would do if redesigning this would be to use voltage regulators with a T03 package rather than the T220. This would likely result in having to buy another heat sink, at least that’s what I’d do if changing these out.

      I am happy to report that the T220s that I put into my power supply have been working fine since I did the repair, which has been quite a while, so you probably don’t have to do that modification.

      Drawings coming…



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