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ATC SCM 150ASL in mid size room?
Old 20th November 2013
  #1
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ATC SCM 150ASL in mid size room?

Hello -

I had a chance to listen some musics from ATC SCM 150ASL and I really liked the sounds. After the audition, I can't think anything else than these speakers and now I want to have them in my living room. One thing holding me out is the room size. The audition was done in a large room, assuming 25' x 20' x 10', but I have smaller room 17.5' x 17.1' x 8' and it's not treated. If I treat the room well (not sure what needs to be done), would the 150 sound good/great? I am sure it won't be like I heard from the large room.

Could you provide me your thought?

Best Regards
Old 20th November 2013
  #2
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Hello,

I don't know about the ATC 150, but I'm in a room a little bit smaller (18 x 12) and have a pair of PMC MB1, who use the same mid driver as the 150, have a similar philosophy about wide dispersion and have a big bass response with the 12" and transmission line loading : they work very well.

Granted I did treat the room HEAVILY : 1 foot of fluffy fiberglass for side walls, and 2 feet for front and back wall, with slats on them to retain some MF and HF in the room.
Old 20th November 2013
  #3
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IB1s don't use the same mid driver as the SCM150s - they use a VIFA mid-dome which is good, but no way on a similar level to the ATC dome.

There's no reason why SCM150s wouldn't work in a smaller room, it's all dependant on the room's acoustics, which in general tend to be worse in smaller rooms, but not always.

The best advice I can give is to just try them out. Alternatively the SCM50 and SCM100 use exactly the same mid and HF components. In fact, the other two models (50 and 100) share identical electronics and drivers excepting the bass driver and of course different enclosure size. You'd be hard pushed to tell much difference between the different models above 50 Hz.

Across the ATC three way actives, all of their speakers use the same crossover points, and with the exception of the SCM25 (which has a version of the mid dome with a smaller magnet as well as a different tweeter), amplifiers, crossover components, tweeters, so if you like SCM150s, you'll also like 50s, 100s, 110s etc...
Old 20th November 2013
  #4
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Quote:
Originally Posted by AlexK View Post
IB1s don't use the same mid driver as the SCM150s - they use a VIFA mid-dome which is good, but no way on a similar level to the ATC dome.

There's no reason why SCM150s wouldn't work in a smaller room, it's all dependant on the room's acoustics, which in general tend to be worse in smaller rooms, but not always.

The best advice I can give is to just try them out. Alternatively the SCM50 and SCM100 use exactly the same mid and HF components. In fact, the other two models (50 and 100) share identical electronics and drivers excepting the bass driver and of course different enclosure size. You'd be hard pushed to tell much difference between the different models above 50 Hz.

Across the ATC three way actives, all of their speakers use the same crossover points, and with the exception of the SCM25 (which has a version of the mid dome with a smaller magnet as well as a different tweeter), amplifiers, crossover components, tweeters, so if you like SCM150s, you'll also like 50s, 100s, 110s etc...
It's not IB1 but MB1, which use the ATC SM75-150S, it was before PMC made their in house mid dome.



sorry for the blurred picture.
Old 20th November 2013
  #5
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I see, my mistake! I haven't heard the MB5 so can't comment really.

If the OP wants SCM150s for a smaller room, then smaller ATCs will fit the bill. I've even been amazed how closely my two-way SCM20s compare to the bigger models.


Not actually affiliated with ATC in any way except owning a pair.
Old 20th November 2013
  #6
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hey, i have ATC 25a pro with Atc SCm .0/12 pro ( C4) sub, and SCM 50ASL also the IB1, i prefer IB1's as my favourite.
Old 20th November 2013
  #7
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Quote:
Originally Posted by Cubic Spline View Post
Granted I did treat the room HEAVILY : 2 feet of fluffy fiberglass for side walls, and 4 feet for front and back wall, with slats on them to retain some MF and HF in the room.
Thanks Cubic Spline for your input and now I am more into 150.
Could you take pictures of the wall treatment and share them here? I am curious about how you setup. Thanks.
Old 21st November 2013
  #8
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Here there are :

- photos of the room before treatment but after the wooden floor
- sketchup of the studio : since I'm renting, the framing stand by itself, screwed in the wooden floor. There is nothing altering the room except 4 screws at the door junction.
- a picture of the walls with the fluffy fiberglass
- photo when mounting slats, following Newell's pattern.
- 2 photos of the studio as it is now : from a 5m65x3m60 initial room, I now have 4m45 x 3m and it is enough for me and 2-3 clients on the couch

Edit : I did post a mistake, it's 1 foot (30 cm) for side walls and 2 feets (60 cm) for front and back wall
Attached Thumbnails
ATC SCM 150ASL in mid size room?-01-parquet.jpg   ATC SCM 150ASL in mid size room?-03-hidden-trap.jpg   ATC SCM 150ASL in mid size room?-sketchup.jpg   ATC SCM 150ASL in mid size room?-stud02.jpg   ATC SCM 150ASL in mid size room?-img_3394.jpg  

ATC SCM 150ASL in mid size room?-img_4696.jpg   ATC SCM 150ASL in mid size room?-img_4692.jpg  
Old 21st November 2013
  #9
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Quote:
Originally Posted by Cubic Spline View Post
Here there are :
- photos of the room before treatment but after the wooden floor
- sketchup of the studio : since I'm renting, the framing stand by itself, screwed in the wooden floor. There is nothing altering the room except 4 screws at the door junction.
- a picture of the walls with the fluffy fiberglass
- photo when mounting slats, following Newell's pattern.
- 2 photos of the studio as it is now : from a 5m65x3m60 initial room, I now have 4m45 x 3m and it is enough for me and 2-3 clients on the couch
front and back wall
Cubic Spline, thanks a lot for the sharing!
Now I understand how you treated your room.
Since I will place speakers in my living room, I will have to place few base traps and maybe diffusers.

I see you placed your speakers next to walls. Isn't there any booming?
I heard ATC 150 should be positioned midfield. Some say nearfield is OK too.
What are midfield and nearfield?
I understood nearfield is to place speakers next to walls. Not sure it's correct.

Thanks
Old 22nd November 2013
  #10
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Quote:
Originally Posted by tyson0828 View Post
Cubic Spline, thanks a lot for the sharing!
Now I understand how you treated your room.
Since I will place speakers in my living room, I will have to place few base traps and maybe diffusers.

I see you placed your speakers next to walls. Isn't there any booming?
I heard ATC 150 should be positioned midfield. Some say nearfield is OK too.
What are midfield and nearfield?
I understood nearfield is to place speakers next to walls. Not sure it's correct.

Thanks
The speakers aren't really "next to walls". first because the front wall is 60 cm deep, and also the speaker depth + speakon connectors takes 60 cm also. So really, the woofer is at least at 1m20 from the front wall. And with that much adsorption depth, SBIR is really taken care of anyway.

I still get a little bit of room gain below 100 Hz, which isn't bad at all for translation
Old 22nd November 2013
  #11
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Quote:
Originally Posted by tyson0828 View Post
Cubic Spline, thanks a lot for the sharing!
Now I understand how you treated your room.
Since I will place speakers in my living room, I will have to place few base traps and maybe diffusers.

I see you placed your speakers next to walls. Isn't there any booming?
I heard ATC 150 should be positioned midfield. Some say nearfield is OK too.
What are midfield and nearfield?
I understood nearfield is to place speakers next to walls. Not sure it's correct.

Thanks
Nearfield's close to you, midfield's further away from you. Nothing to do with the wall.
And yes, it could get problematic in the lower frequencies by placing speakers close to the wall, but it's one of those things where you just have to try it in your space and see how it sounds.
Old 22nd November 2013
  #12
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Quote:
Originally Posted by dbjp View Post
Nearfield's close to you, midfield's further away from you. Nothing to do with the wall.
<SNIP>.
Close to the wall is typically a problem with first reflections. Tremendous energy coming off the walls when you put a speaker close. Completely changes the sound, the longer path reflections and the shorter path direct sound sum at your listening position and change the response through the combination of in phase, partially out of phase and completely out of phase info. In Cubic Spine's room (amazing build out!) he shouldn't have that problem as the side walls are not reflective as they normally would be. Using absorption on the walls at the first reflection points (next to the speakers) is the first step from my experience.

Brad

Last edited by Brad Lunde; 25th November 2013 at 05:36 PM.. Reason: improve sentence
Old 25th November 2013
  #13
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Quote:
Originally Posted by Cubic Spline View Post
It's not IB1 but MB1, which use the ATC SM75-150S, it was before PMC made their in house mid dome.
ATC stopped selling PMC their mid dome in the mid nineties, so these PMC's are nearly 20 years old....

Brad
Old 25th November 2013
  #14
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I do believe the current upper end mid like the radial driver they claim as there own is a Volt built Driver.
Old 26th November 2013
  #15
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From what I can tell after some searching on the net, several different sources (but none of them PMC themselves) claim that the PMC IB1S and below uses a Vifa 3" D75MX 31-08 soft dome mid driver, or possibly the D75MX 41-08 that's also used by the Quested V3110. The IB2S and above are said to use a Volt/PMC mid, or one that is hand-made by PMC.
Old 26th November 2013
  #16
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Dome is build in house : HiFi Unlimited: PMC Factory Tour, Part II. Hifi Trio Visits PMC!

The bass driver is build by Volt to PMC specs.
Old 27th November 2013
  #17
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Quote:
Originally Posted by tyson0828 View Post
Cubic Spline, thanks a lot for the sharing!
Now I understand how you treated your room.
Since I will place speakers in my living room, I will have to place few base traps and maybe diffusers.

I see you placed your speakers next to walls. Isn't there any booming?
I heard ATC 150 should be positioned midfield. Some say nearfield is OK too.
What are midfield and nearfield?
I understood nearfield is to place speakers next to walls. Not sure it's correct.

Thanks
Technically nearfield means that more than 50% of the total sum of acoustic energy at the listening position is coming directly from the speakers. Farfield would mean more than 50% of the total energy is being re-radiated by the room.

But the terms don't mean all that much relative to marketing terms used loosely to describe being close to a speaker or not.

Typically most speakers are not designed explicitly to be free-standing or wall or wall/corner loaded or fully soffit loaded. Ultimately IMO it's wise to either have position available as an option to adjust that, or DSP available, or both. These days I personally think it's borderline crazy not to have dsp...but that's just my opinion.

It is a complete fallacy that big speakers don't work in small rooms. The main thing you want to look for to determine the closest listening distance is the distance between the center of the mid range driver and the tweeter center vs the crossover frequency. The lack of point source on a typical multi-way means there will be what is called lobing; areas vertically off axis that will exhibit dips in the frequency response. We want to be sure the lobes are above and below our ears.

The rule of thumb is 13500 (speed of sound in inches per second)/driver center distance in inches = highest crossover frequency for 3ft distance. IE typical bookshelf speaker has say 6" between the center of the woofer and the center of the tweeter, so 13500/6=2250. So the crossover point should be 2250 or below for a 3ft listening distance. If the point is lower, you can effectively move in a little closer, or if it is higher you should avoid sitting too close as the vertical window for lobe free sound will be very small.

The slopes of the XO are a factor as well but this is a good general guideline, hope that helps.
Old 27th November 2013
  #18
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Some very good points in your post, RyanC.

If I may interject with a practical note: While having debunked the myth that big speakers don't work in small rooms, one of the remaining obstacles against using big speakers in small rooms is that you get fewer placement options. Larger cabinets will take up more room volume, resulting in less maneuvering space. If the speakers are both large and heavy, you may be required to place them on proportionally large stands. Vertical placement also becomes extremely limited, maybe as little as +/-20cm in small rooms. And since the speakers are heavy, you can't explore options such as makeshift stands and wall/ceiling mounts. In the end, with large speakers in small rooms you may end up having to make the best out of the "least bad position" that you can find.

A related discussion is the one about "what is best of a full-range 2.0 system and a 2.1 system". If you decide to go for using a subwoofer, you should in principle have many more placement options, which allows you to experiment with placing the subwoofer in an optimal position with regards to room interaction. But in practice, you may realize that in a small room your options are actually really limited: You more or less have to place the subwoofer on or slightly above the floor, so that's one boundary you can't avoid. And if the essential furniture takes up too much real estate of your floor area, there may perhaps be only a few practical locations left to try your subwoofer in. And on top of that, you will have to compensate for the offset position using bass management and crossover design.

A classic conundrum when designing small studios, is forgetting to take maneuvering space and other practical issues into account. It may all look great inside your design application, until you set things up in real life and suddenly realize that you underestimated the actual size of things.
Old 27th November 2013
  #19
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Originally Posted by Hjelmevold View Post
A classic conundrum when designing small studios, is forgetting to take maneuvering space and other practical issues into account. It may all look great inside your design application, until you set things up in real life and suddenly realize that you underestimated the actual size of things.
Absolutely true.

But ultimately the bass modal problems in a room increase in inverse proportion to the room's volume, as does Schroeder frequency, and the inverse square law is working against us.

To me the choices are either A) 'Nearfields' that are not full range and definitely not able to approach any sort of desirable house curve as far as *full* bass goes but not aggravating modal problems, B) Full-rangers with the downside that the bass might not be quite right, C) DSP. All of that assuming that we have used as much of the rooms volume as possible for bass traps/damping of modes. And there is the sort of quasi D option of multiple subwoofers (it does work, but requires DSP or very custom passive crossovers).

In any case a small room is a challenge. Maybe SCM25's and a 15ASL would outperform the 150's...but I think the big question there is DSP. Personally I think a sub without DSP is too hard to get good (or great) integration in spite/lieu of it's movability (which is limited as you point out). With DSP and some practice you can get there, but a lot of people are deathly afraid to mess with the voicing of their monitoring like that (understandable, it is a bit of a rabbit hole).

Sans DSP I guess the 150's offer some benefits and some drawbacks when compared to other options (physics is a fickle mistress like that), but they would fare nicely side by side (my guess). The sm75-150s mid dome is a special piece IMO, I think the only thing that bests it is large format beryllium diaphragm compression drivers on SOTA waveguides (maybe ESL or Manger BW but low spl is a problem for audio with a high crest factor like we have in the studio). I haven't heard the 25's though to compare to the 150's...YMMV.

But sure the layout of the room, placement of the speakers/subs, the treatment and inclusion or not of DSP are all factors...maybe the better question would be if you are going to be 40k into monitors then why not spend a little more on a bigger room? But, for the time being I'm stuck in a smaller space myself, as are many of us...
Old 12th December 2013
  #20
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I had my 150's in a pretty small room for a while, (13x17) and loved them.
Was sitting very close to them so it looked a bit ridiculous but sounded awesome.

I also have a set of 25's and had them side by side.
Now I love my 25's but do prefer the tweeter in the larger atc's and there is something special about how linear and extended the 150's are.

150's are now in my new mastering room and 25's remain at home in my writing room. Lovely going back and forth between them.
Old 13th December 2013
  #21
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My "music room" is 17'x13'x(9-7)' in size, and I have PMC IB2S as my main monitors driven by NAD 208 (400W per side to 4 ohms) and a Genelec 7071A sub lurking behind the curtain (twin 12' long throw drivers). Behind the same curtain is a 70 cm deep storage space filled mostly with clothing and camping gear functioning as a dead end in otherwise nicely live room with wood paneling. I do not feel these speakers, which are almost the same size as the ones you are contemplating buying to be too big for the room what comes to sound, bit voluminous, yes. Actually these are about the size of SMC50.

I would also suggest that you look at the smaller versions also like SMC50 and add a sub, as the combinations is easier to align to the room. These PMC IB2S boxes are the smallest ones with the best mid-high driver combo PMC has to offer, getting the ones with 12' or 15' woofer did not make any sense in my case as I already had the large Genelec subwoofer and everything below 85 Hz is filtered away anyway.

Needless to say they sound just about better than I have heard anywhere.

ADAM A8X in the middle, ADAM A7 near field monitors at the desk double as rear channels for 5.1 MCH.
Attached Thumbnails
ATC SCM 150ASL in mid size room?-music_room-small.jpg  
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