SM Pro has released a “passive summing mixer” that mixes eight analog audio channels to two. The idea is that digital summing, as performed in software, will cancel certain sound components and result in a less detailed mix after mixdown. The PM8 passive summing mixer does this for you in the analog domain, theoretically resulting in a better mix.

Here’s an excerpt from the marketing materials: “The summing and mixing features built into the PM8 allow users to avoid unnecessary A/D & D/A conversions commonly found in digital studios and thus attain extremely detailed mixes with superb stereo imaging and punch.”

PR is actually mixing metaphors here. Summing in software has nothing to do with A/D or D/A conversions. What I think they mean is that, by connecting analog inputs directly to this mixer instead of routing through your software, you won’t have to go through additional conversions; that much is true.

The manufacturer also claims that the mixer “Achieves better stereo imaging” and “Creates exceptionally detailed mixes with clarity and punch.”

PM8 Product Page [SM Pro Audio]

I’d sure like to hear an A/B test of digital summing in music software with analog summing, with all other variables minimized as much as possible. Mostly what I hear is people arguing over this based on these issues based on hearsay or theory. Certainly, a good passive mixer will have uses in studios, for those who can afford / actually need them. But my question is, does digital summing really deserve all the flak it gets? (My mixes aside; I don’t think you need fancy equipment to hear more detail in my mixdown as I’m no engineer!)

Maybe Bob Dylan will want one?

  • Tail Tyle

    I think it is witch doctor territory myself. Correct me if I am wrong, but mixdown is suppose to be as colorless as possible. If you are mixing down at a high enough sample rate and bit depth, there should be no problem.

    I think studio guys are a lot like sailors… they know what they are doing for sure, but there is a lot of superstition mixed in with their knowledge.

  • dank

    3D Audio makes a daw/sum side-by-side comparison cd. highly rated by folks that care about this sort of thing.

    i've not heard it. while i believe there are benefits to external analog summing, i don't think those benefits are enough to cause me to make different mix decisions. we're talking subtle stuff, here.

    it might be fun to start playing around with these things just prior to sending a cd off to be mastered. in other words, "the mixes are done, let's see if the stems sound better pumped through this analog box."

    they probably will.

  • vallen

    I recently heard a Pro Tools vs Dangerous 2-Bus comparison and the Pro Tools mix sounded much better, in my opinion. Although, I totally expected better imaging from the 2-Bus.

    I'd actually like to get my hands on one in the near future to make my own comparison.

  • That's great; I hadn't seen that! You just need to grab a friend and make sure it's a truly blind test. 😉 Only bad news: I notice Ableton Live is absent.

    One thing I think you can say pretty fairly is that summing is *not* that difference among most DAWs. I know you can do a side-by-side Logic / Live comparison and there's perfect test signal cancellation in each.

  • vallen


    I've heard a side-by-side comparison of Pro Tools and Samplitude (Windows) and I almost wanted to cry. The algorithms that they use are amazing, I have to say.

    Not all DAWs are created equal in that regard. I'm working on one now, as a matter of fact (for Mac) and that's something I'm focusing my attention on. ;]

  • I assume it was Samplitude that made you want to cry, not Pro Tools, correct?

  • vallen

    Samplitude sounded very nice.

  • TinEar

    I'll refrain from commenting directly on this product as i have not used it myself but any company selling a mixer as passive and then slipping "The PM8 offers a transparent active gain make-up stage" into the blurb… well I'll just have a truck load of your magical transparent active gain make-up stages please.

    I'll then pop it in downstream from this well known circuit!

    How can attenuating and then amplifying one's signal be worth the cost and hassle of this thing?

  • kevin

    There is no "better" in analog summing.

    I prefer digital summing anyday. Where do you start with analog summing (which flavor will i need) ?

    Analog colors the sound and this is what some people like. If i buy this (another) summing mixer, it might be nice on this song but another it will just screw it up because it colors.

    Wider imaging has to do with :

    1: good a/d, d/a and clock

    2: the skill of the engineer and mixer

    It is another lie in the marketing world.

    and don't let me start on this:

    "Without getting too technical about it, the upshot is that your mixdowns will simply sound better as a result."

    Your 500$ converter with 8 crap d/a ouputs will suddenly sound amazing thru this analog summing box….


    good luck

  • vallen

    Kevin, you're right on! I really wish more people would use converters from a Lavry, Weiss, or Troisi. Instead, they give into the lie that a Big Ben will make their $300-500 192 kHz interface with sound better. Nothing beats a good converter with a good internal clock.

    Although I haven't ever used a summing box, I'm interested in hearing for myself how it would impact a mix.

    I'm using a LavryBlue connected to a 192 Digital I/O and I've never been happier.

  • Damon

    I certainly hope it works.

    I imagine that the result would be more impressive if there was more happening there than just combining sounds. It sounds like a whole lot to accomplish very little. Your engineer may be impressed, but your listening audience may not be able to tell the difference.

    But maybe a belief that it is accomplishing something great, will have a positive effect on the process, but that still adds up to not much more than the placebo effect.

    I wonder if this device would have more benefits in the sound design zone. I cannot help but presume it has some magical ability, but I am not sure if the currently intended application is where this device belongs. Were you to make some adjustments to the design, would this thing add up to a very fancy morphing type of effect, in some fashion allowing 2 or 10 very diverse sounds to harmonize into something unique and wonderful? I do not know. Maybe I am misunderstanding the concept.

  • Vermeer

    To me summing boxes are a way for "old school" analogue mixers to continue using the mixing methods they have used for so many years: record as "hot" as possible, then use tape saturation and solid-state distortion to get pleasant-sounding results.

    These tricks don't translate to digital. Recording tracks in ProTools at very high volume is useless, tape saturation is impossible without tape and solid state distortion is just not there.

    Digital is a different medium. It's like the difference between using a pencil and a mouse: you can't use the same technique, but it helps to know how to draw.

  • Well, yeah, Vermeer, I'm with you. I think the purpose of this box is probably for people using analog techniques to avoid the digital box entirely. Now, the idea that it magically fixes your mixes by running through it is just absurd, but the person who designed this and the person who wrote the press release are almost certainly different people. Still, it's frustrating to me to hear talented engineers who do suspect digital mixing without really giving it a close listen — especially ironic, because in a truly blind test I'm sure they'd have much more to say about it than I would.

  • Theron

    About a year ago, Electronic Musician was all about analog summing buses. Then about six months later, there was an article in EM about how they're basically snake oil. hmmmmm….

    Hey, I'm sure you can achieve some good results using analog summing. You can get good results in-the-box as well. It's all about being reasonable and using your ears and not buying into whatever the latest gear fad is.

    Regardless, most of these units only have like 8 inputs anyway. I'm sure there are plenty of folks sending multiple tracks to busses to cut it down to 8 tracks before "mixdown." If you do that, you're basically relying on digital summing even more than if you were to just digitally bounce your session down to a stereo track.

    What I imagine people find appealing about the analog summing sound is actually just added analog noise smoothing things out. If that's what you're going for, there are many cheaper ways to achieve the same result.

    I don't want to come off as an anti-analog bigot. In fact, much of my rig is analog, and I sometimes like to slam things to both reel-to-reel and cassette 4-track to get that certain vibe before I go into the DAW. I don't much care for virtual instruments–the polymoog and arp odyssey are my weapons of choice. But that's just my personal preference.

    Don't buy into the hype. Rely on your ears, what sounds good to YOU.

  • Vermeer

    Another thing I've noticed is that for a whole generation of audio engineers, software is really hard to apreciate: they need actual knobs to turn.

    One thing I find interesting about the old guard is that those who have managed to sty sucessful across many decades have never stucked to one technology: they evolved and many times were early adopters.


    * George Massenburg – Invented parametric EQ hardware in the 70's, but now makes equally good plug-ins and produces on Digi Icon boards.

    * Roger Nichols – This guy teaches ProTools for god's sake! Started in the late 60's. He never looks back.

    * Michael Wagener – Can't keep him down. His studio is totally digital. With a quite a few few outboard (

    If these guys can keep up at 55+, so can everyone else.

  • please: no A/B tests! no mentions of A/B tests! no references to A/B tests! double blind is the only acceptable testing strategy in every other field where testing matters, and it should be the standard here too.

    oh and peter, i really will email you soon.

  • Oh yeah, absolutely. That's why I suggested getting a non-partisan friend to help. 🙂

    The moment you say, "Now, here's what Pro Tools sounds like –" it's not terribly scientific. 🙂

    Thanks everyone for ranting. That's really my thinly veiled reason for bringing this up in the first place.

  • vallen
  • Kevin

    The reason why DAWs sound different and why analog gear sound different is because you use it differently. I get a much better sound in recording and mixing with Logic than with Protools LE.

    Because for me it is more user friendly and less irritating (mainly PDC missing in Protools LE). It's more fun to work in logic for myself so it is fairly logical that it will sound better because i'm more into it.

    I'll bring out the best out of everything but a mix i did in protools or in logic will sound differently.

    If you mix with an analog summing buss , there is no logical sense to only bring it in after it is mixed. You mix together with the buss, not connecting it later to bring more analog into the picture because you already agreed that the mix is done.

    So a/b tests never work with mixed materials.

    What you can do, is do mix in stems (not because it will sound different than a stereo ITB bounce) but you can now put a fairchild UAD for example on each mono stem (always mono tracks)

    The reason why analog sounds different is because there is no stereo ! Each pro console is made of mono busses, mono compressors, etc…

    Spend the analog summing box money on better a/d + d/a + clock.

    And work in mono tracks and mono effects ITB.

  • I just bought an extra patchbay and some extra snakes so I can analog sum.

    I use an allen&heath GL2400 (direct outs are post pre,eq,fader). Then dumps into an 002. For channels 9-16, I got a behrenger ADA8000 AD/DA box. My gear is balanced throughout.

    I do all my recording at 48K/24bit. My intention is to record into pro-tools/Logic strong and use the full bit depth, do some effects and copy/paste stuff. Then blow it right back out onto the allen&heath.

    The final recording device being a akia Z8 recording the mix@ 96k/24bit.

    Will it make my mixes sound better?

    I don't know

    Can a magic box make a crappy D/A sound like a Neve?

    Probably not.

    Will having a clients first real recording spread over my console so he/she can "touch" it a little bit in the raw form make for a more interactive session?

    Most likely.

    Will having the recording spread over the board for the client to touch allow me to charge an extra 5$ an hour.

    Pretty much, but just kidding.


    If the trend is selling snake-oil:

    Start a franchise.

  • ep

    Folks…Heres my take on this kinda stuff… If you want that legendary "ghost sound", you are only as weak as your weakest link….Going back to analog after digital etc,, doesn't buy anything.. You killed that "spirit" when you converted to digital, atleast your last picture of it.

    Anyway.. heres the secret….Record in the best studio room possible, with the best analog tube mics, to the best analog console/preamps, to the best analog tape deck, at optimum levels.. DO NOT color the sound to this point…If you can't afford the above, then rent time in a pro studio with the above goodies.

    In that studio, use the best a/d converters (like Radar) and bring the tracks into Protools….At that point, you can mix, add color and screw as much as you like with the plug-ins…at least you can always go back to the tapes.. Then leave the rest to the best mastering engineers. Das-de-Mojo sound baby!!!


  • Baxter


    You may want to investigate a better clock than the 002 is running. The addition of an Apogee clock to my 002 rig was amazing. The bass and lower mid's became 3D instantly, changing the mix considerably. It didn't "add sound" or color it, it simply revealed what was there.

  • Wilhype

    I have mixed songs since the early Ninties on analog gear with analog tape and it sounded great if the mixer was decent, When digital came along it was a marriage made in heaven. I will take a digital source with good analog mixer over mixin IDB anyday. Yes it sounds g8 (InDaBox) till you max the level after mixdown and thats usually when you hear its inability to compare with the width and dynamics that a good console can provide. I have heard some good IDB mixes and I have heard what Dr.Dre and Timbalind get when they use a neve or ssl with protools. There is no comparing the 2. Mixes IDB bottlenecks thats why people are usin and creating these summing units. I you hear a mix from analog summing on a dangerous and it sounds like crap its obvious the engineer is not very good at it. most people never had a chance to use the older gear and would likely take years to learn how to get that older stuff to sound great. The art of mixin is taken a turn for the worse because newbies havent mastered the hardware devices.

  • Hey Guys just to get into this topic I agree with Wilhype… I've been working on large format consoles and have been doing the DAW thing for awhile now.. and at the end of the day it all boils down to your ability understand the strengths and weaknesses of digital and analog and utilize both technologies.. at the end of the day u need a decent front end preamp and good AD/DA such as mytek or lavery… then you need to sum out of the box to in order to get the headroom …depth…and separtion in the mix… as far as I'm concerned 80-90% of most "commercial" albums are still mixed through an ssl and tracked through a neve for a reason!!! That sound that the analog transformer technology imparts!!! As well the knowledge and approach of old school recording still stands tried and true

    That's my take on it!!!