Thinking of buying a microphone multiplexer. Change my mind!

[Jon Dent]

The most recent calibration I did for our two theaters was with a single Behringer ECM8000 mic using the internal RTA of the CP750. It sounds okay but I'm wondering whether I should invest in a proper microphone multiplexer to do it right.

Is it worth that kind of expense? They're pretty steep, but if it ends up being useful it's a manageable cost. Plus there are a couple of other audio spaces I work in that might benefit

[Tony Bandiera Jr]

In one word, yes.

In other words, if you have other venues where it would be useful (and charge for your services accordingly) you will recoup the cost fairly rapidly.

Finally, get one now while you still can, as the supply crisis and "other issues" will most likely make a MUX either unobtainable or at a steep price increase.

I sold mine some years back and regret it, as there were situations where I could have used it and made some money.

[Harold Hallikainen]

Measuring frequency response with one microphone is certainly problematic due to standing waves at some frequencies at some locations. Averaging several microphones smooths out this issue (different positions have nulls and peaks at different frequencies). I think the Octocapture (I think that's the name) used with the CP850 is an interesting alternative to a multiplexer. It simultaneously captures 8 microphones and software can combine the frequency responses. This is a more standard product (used in other markets), so is likely to be less expensive. Also, since all microphones are being sampled continuously, the system is faster than one microphone at a time with a multiplexer.

Harold
(worked on the USL multiplexer)

[Randy Stankey]

Would you use it?

If the thing would spend its life in the closet, somewhere, with all your other rarely used things, don't waste money.

It is possible to get a good tuneup with just one microphone. You just have to do more work and you have to use a few more brain cells but you can do it.

I knew a guy from a sound company who had such a good intuitive sense of his work that people jokingly said that he could "see the sound waves."
He DID do it with one mic! He would walk around the room and listen. He'd put the mic in one place and make some adjustments. He'd run some music and listen then do it again. It only took him two or three tries to get the room sounding so sharp you could shave with it!

If a MUX is something you would use often enough to make it worthwhile, get it. No question!

If it's going to be used as part of your business or if you would use it often, the money spent will be put to good use.

Bottom line: For technical purposes, yes, but you need to ask yourself whether you would get your money's worth out of the purchase.

That sound guy is the one who showed me where all the nodal points were in the auditorium at Mercyhurst. He took me around and made me listen to the sound in one spot then he told me to move three feet to my left or right.

He did it, mostly, by looking around the room and seeing the different structures like the balcony and the doors and things. Yes! He could tell you what the sound of a particular room was going to be just by walking around and looking!

Like a magician, that guy was!

[Jon Dent]

Randy, I would use it for the initial tunings of course, and then periodically for tune ups. Is it going to get frequent use outside of that? I honestly can't say. But I'm approaching it more as a business investment, same as my camera equipment that might only get used 6 times a year, but it brings the money when it is.

[Stefan Scholz]

Since I have been getting my R2 in the mid 1990s, I have been relying on multiplexer based setting of sound systems. Meanwhile used is the D2 kit, but that's solely been for weight and for the Dell laptop from 1993 showing a disintegrating plastic shell.
It was possible to get very consistent results over all the years. And systems that have reputation for good sound. It is not solely the technology used, setting up has more to do with the basics, eq as little as possible, and correct errors first. Use appropriate (sizewise) components, employ ample headroom. And Listen!, using well known stuff. Plus keeping in mind, that's not 85dBC you aim for, it's 70 dB @ 7.0 fader.
I would never use a multiplexer and auto adjust on a processor, even though I have to admit, what Dolby does on the 850 and 950 works pretty nice for a general start, or a quick job.

I like the octa capture approach of a (digital) mixer with preamps feeding simultaneously into the audio analyzing circuit. For that approach, you won't need an Octa Capture box, any multi channel mic capable preamp/ mixer will do. All you need to do is calibrate your input on the analyzer to match the mic calibrator level.
A regularly calibrated class 1 mic calibrator is probably more important, than a multiplexer, as it is important to set correct playback levels. As you need to know the exact SPL level with your mike.
Such a calibrator eventually is the expensive item, taking cal against a NIST standard cost into consideration.

[Leo Enticknap]

In the Atmos tuning school, I was taught that calibrating the mics using a barrel-type cablibrator that emits a 94dB beep and SMAART is an essential preparation step in the process.

Compared to some of the gear we use for digital installation and service, Octacaptures aren't that pricey - around $600 on Amazon. But once you add 5 to 8 reference mics with stands and cables, a calibrator, and a SMAART license to that, the total kit cost is around $2-3K.

[Mark Gulbrandsen]

Better yet buy the ovation cinema processor and their microphones and it completely sets itself up automatically. It also has the best sound quality by a long shot.

[Marco Giustini]

Mark,

And when tuning a non-ovation room? You swap the sound processor?

A multi-mike is a must in my opinion. I learnt very early in my cinema career that a single mike is mostly a waste of time (unless, as Randy said, you invest some time on it, moving it around, doing averages etc). The Smaart solution is, IMHO, the most flexible.

One word of advice: do not think that if you buy a multiplexer, this will give you 100% from your sound with no efforts. Placing your mikes around the room, doing an EQ as per the manual and *walk away* will STILL result in a poor job - ok, maybe less poor than using a single mike.

[Mike Babb]

I don't think you'll find much debate that a 4 mic look at a cinema is better than a 1 mic look. I have used both D2 and Smaart, much more familiar with D2 and have had great results. Smaart is capable of looking at delay and phase, although I suspect cinema techs are rarely using it for that.
Re Marco's comment, a couple years back we made the Ovation and now Ovation2 capable of accepting mic calibration files from D2 and Beyerdynamic MM1 which seem to be the most commonly used mics in cinema. I use both brands of mics myself but much prefer the D2 for portability and weight. I have the studio version with the MOTU 4 which I find convenient and reliable.

[Marco Giustini]

Smaart is capable of looking at delay and phase, although I suspect cinema techs are rarely using it for that.

That is the sad part, which I kind of summarised with the "even if you have a multiplexer, dialling the curve and walking away will still result in a poor result".

I have both the D2 Studio and Smaart and - particularly on difficult rooms where acoustic is not great etc - listening to known content is not an option, regardless of how many mikes you spread in the room!

[Mike Babb]

Agreed Marco, this is why I have come to believe in measuring time response, phase, direct frequency response and room response, and impulse response. Ioan Allen and John Allen had articles years ago about the reasons an RTA with room response can cause you to not only over EQ but over EQ in the wrong direction.

[Gordon McLeod]

I use the D2 almost exclusively and still have my reliable R2. In large rooms I never use direct response as Allen does as it doesn't look at the big picture of the combinations of the room and the equipment. Impulse measurements can be helpful but fix the problem with the room first acoustically

[Marco Giustini]

the bottom line is that there is no simple and definite way to EQ and achieve 100%. Everything affects everything. Yes, Mike, I agree that measuring everything helps, as it gives you more tools to work with. As Gordon says, acoustic plays a huge role in the final sound.
More tools are never a bad thing.

But - my opinion - so far there isn't a unique tool that allows you to "walk away" without a listening test with confidence that the sound is 100%.

To go back to the original question: the multiplexer is a "must have" tool in EQ'ing a room, but it's not magic.

[Randy Stankey]

This is like comparing a paintbrush to a Wacom tablet.

Each will allow you to paint a picture but in different ways. Each has its own advantages and pitfalls. You have to learn how to use them and decide how to fit them into your workflow. In the end, it's all about whether you find a certain tool useful to the way you work and adjusting the way you work to the tools at hand.

I've gotten good results with an analyzer and a MUX but, as above, I've known people who can do the same thing, pretty much, just by listening.

If you think you can make use of a multiplexer there is no reason not to get one and there are plenty of good reasons why you should.

In this case, the way I see it, the only factor is the cost and deciding whether it will be used frequently enough that it would be a worthwhile expense.

If you think that you can use it in your business enough to, at least, recover the cost and, hopefully, to profit from it then I say, "Go for it!"