Full Review of ATC SM75-150S Midrange Driver

[Jeff B.]

Re: Full Review of ATC SM75-150S Midrange Driver

Thanks Jeff.

Would like to see comparison tests to get a sense how one driver compares to another. I know, completely impractical. Different crossovers, different baffles ... For example, would like a comparison between these ATC's and Tang Band 3" dome or a BG Neo10. Not to state which is better or better value, but how they are different.

That would be fine, but I don't have any of those other drivers, and they would need to be tested in a controlled system to clearly define their differences.

[isaeagle4031]

Re: Full Review of ATC SM75-150S Midrange Driver

I'm sure it's just a drive to Nashville......

I know and I will be down there in Aug.

[Jim Griffin]

Re: Full Review of ATC SM75-150S Midrange Driver

isaeagle4031,

The new owner of these awesome speakers that Jeff designed lives in Franklin, TN.

Emotiva's Emofest (open house at their Franklin site which includes live music, lots of food, equipment demos, and exceptional door prizes) is usually over Labor Day weekend (sh'be August 30-31 this year) for what it is worth.

Jim

[Jeff B.]

Re: Full Review of ATC SM75-150S Midrange Driver

isaeagle4031,

The new owner of these awesome speakers that Jeff designed lives in Franklin, TN.

Emotiva's Emofest (open house at their Franklin site which includes live music, lots of food, equipment demos, and exceptional door prizes) is usually over Labor Day weekend (sh'be August 30-31 this year) for what it is worth.

Jim

Well, I've completed the crossover design, but the cabinet tested is just a test cabinet. The real cabinets are still in flux between him and cabinet maker. He may even go with a machined aluminum baffle, but that hasn't been decided yet. Finished speakers in Franklin are still a ways off.

[mzisserson]

Re: Full Review of ATC SM75-150S Midrange Driver

Hi everyone,

I have been asked to design a studio monitor using the ATC SM75-150S 3" dome midrange driver. Since this driver is so hard to get your hands one, and since it has near-legendary reputation as a mid, I thought I would submit of full review with measurements and subjective listening thoughts. You can download the full review in pdf form here: https://app.box.com/s/j1pwj8exbmioz350nu0n

Comments are welcome,
Jeff B.

Very nice Jeff,
Makes sense to me, it is always nice when the objective performance backs up the subjective. It is an exceptional mid and I was shocked when I heard it expecting the honk of a large dome but it is one of the best mids, let alone domes, I have heard.

[Jeff B.]

Re: Full Review of ATC SM75-150S Midrange Driver

Hmmm.... this thread has a pretty poor rating. I thought I provided a fairly informative evaluation of this driver.
Jeff

[bkeane1259]

Re: Full Review of ATC SM75-150S Midrange Driver

Hmmm.... this thread has a pretty poor rating. I thought I provided a fairly informative evaluation of this driver.
Jeff

Does anyone look at those things anymore?

EDIT: anyway, you'll really know how popular it is by looking at the Box.com stats.

[Ryan_M]

Re: Full Review of ATC SM75-150S Midrange Driver

I thought it was a great review! I'm sure I'll never drop the coin for a pair of these but it's nice to know some of these high-end pricey drives are actually worth the money they charge for them and not snake oil. Hopefully they will inspire some other manufacturers to produce a similar unit at a more modest price.

[craigk]

Re: Full Review of ATC SM75-150S Midrange Driver

Hmmm.... this thread has a pretty poor rating. I thought I provided a fairly informative evaluation of this driver.
Jeff

I think the review is informative and well written. Maybe part of the issue with the rating is the fact that the design is using two drivers that are unobtainable by the DIY community. If you could purchase the drivers the price alone would limit the majority of people from building this speaker. When a standard pair of ATC SM75s run 1200.00 dollars, I am sure the "S" version adds a few more dollars. Toss in a couple of tweeters that are going to be in the 1500.00 plus range, if you could purchase them. Not to mention the woofers, x-over cost, I am sure you see where this is going. It is nice to read about a speaker that is a true high end product, that you might have a chance to listen to, and that maybe if you saved your money up you could actually build. The DIY community will never have the chance to do any more than read about this speaker. So when it comes down to the basics I think this might be part of the issue.

[Greggo]

Re: Full Review of ATC SM75-150S Midrange Driver

Jeff,

Thanks for the great review and starting a thread on this classic driver. I have certainly never "voted" on a thread before, just figured out how to do it...

Anyways, it was great to see the measurements, comments, references and some nice pics all in one place. I am sure more than a few folks will download that PDF even though they may not comment here. I have always been fascinated by this mid and a few topics that always seem to come with it:

1) Can a cone or planar ever match its performance? I believe around the time of its introduction, the leading contenders were the small scanspeak paper cone and the larger lowther drivers, so today I suppose we would add the illuminator mid, the accuton, the morel you recently referenced, the SB Satori, Tang Band and Dayton full rangers, the BG Neo 10, the Beyma 12P80Nd and the AE 10 or 15 M series. All seem to garner big fans in various designs and get mentioned as being among the very best midrange transducers. Of course, there is no real answer to what is best, but it is fun to get various opinions and occasionally get a chance to hear them in a design every now and then. Few drivers ever seem to get such consistent praise as this large mid dome however, and in the end I find that fact a bit depressing given how hard it is for anyone in DIY to get their hands on it, especially those of us with real budget constraints.

2) What exactly is the "midrange" frequency range anyways? For me anyways, I like that this driver forces the designer to dive into crossover points that are usually avoided, at least by many of the designers I have followed over the years. The lower crossover point of 300-500 Hz I suppose is not that uncommon for 3 way designs, but certainly presses the 200 Hz or lower crowd of which I have been a subscriber (as an armchair designer of course), and even more so those that like to stay at 100 Hz or less. Then there is the upper limit which doesn't quite go far enough to get out of the danger zone of mid/tweet transitions so that you would just add a super tweeter and call it a day. Nope, you gotta work the crossover real close to where we are the most sensitive to freq, phase, and location between drivers... And yes, this is all up for debate and I know that you specifically have responded to my posts before with the notion that you let the math drive the selection of crossover points and don't worry about any folk lore around some points being better than others. I am sure this particular design will be as good an example as any to support that position.

3) Flange and overall physical size vs range covered... I believe the only time I have ever seen this driver used in an MTM design was one of the ProAc floor standers. Given the frequency range issues described in #2 above, is it possible to get any combination of drivers on a baffle and have them integrate well with two rather than one of these mid domes? That seems like a very difficult task given the lobing issues at the upper range and the flange of these drive units. Is there even a reason to ever need to? Probably not, but you know the first thought is always that if one is great, then two has the potential to be super great! At least that is where idiots like me always go for lack of any more profound insight.

Anyways, thanks again for the review, it really was a nice read and brings back a lot of memories of various folks giving this driver a try over the years. I will go back to bugging Dave Pellegrene about his experiments with the TB 75 even though I am starting to feel the pull of line arrays again and looking at the Neo 8PDR among other things...

[jonasz]

Re: Full Review of ATC SM75-150S Midrange Driver

Jeff, thanks for the review, love threads like this!

The std version is available here, though not cheap: http://www.wilmslow-audio.co.uk/atc-...ange-475-p.asp

Wilmslow also sell the similar (even more expensive) Volt VM752 driver. http://www.wilmslow-audio.co.uk/volt...unit-499-p.asp

[Juhazi]

Re: Full Review of ATC SM75-150S Midrange Driver

^^Can a cone or planar ever match its performance?

Audax HM100Z0 has some reputation as a good midrange and is in production again. http://www.madisoundspeakerstore.com...ogel-midrange/

Here is my measurement of it in narrow test baffle, there might be some extra distortion - measured at 1m UMIK-1 and REW

[henry218]

Re: Full Review of ATC SM75-150S Midrange Driver

i remembered few years ago, a friend of mine demoed the atc dome on its own, free air (although they are sealed, but you know what i mean), what i heard was a full dimensional sound in just 1 driver, i was pretty new for building speakers that time, but it was so special and spectacular that i still remember until today.

to be clear, the driver was sitting on the floor, connect to a TV (he was making a point to me that time, and i have heard the excellent SCM7 already), the driver managed to project a believable sound of 2 person in the room, walking across with footsteps sound, i couldnt believe i can hear / see the room ambient from a single driver on the floor.

[Paul Carmody]

Re: Full Review of ATC SM75-150S Midrange Driver

Hmmm.... this thread has a pretty poor rating. I thought I provided a fairly informative evaluation of this driver.
Jeff

I wouldn't take it personally. I think someone's just goofing around with the ratings system... kind of like the tags system, although the tags are actually sometimes useful, whereas the ratings are not.

What you did was good, Jeff. Don't sweat it.

[Wolf]

Re: Full Review of ATC SM75-150S Midrange Driver

When I held it last December- I knew there was magic in my hands.

Good to know it stacks up, and I would also like to hear it....
Thanks, Jeff,
Wolf