There is no ATC SCM150ASL Pro review or frequency response curve.

[574stereo]

At face value, The front baffle of the KH420 looks more like what any front baffle should, nice curves, smooth, no sharp transitions. Is it the end of the world if a cabinet has 90 degree corners? How could it be ATC and others do it anyway. Does it impact performance? 100% and it makes a difference in the final result. Take the ATC drivers and upgrade the baffle and yes the performance will increase. Its not even a big deal and its loudspeaker design 101. Is it the reason why the guys above liked the Nuemann better? No idea lol but do I trust their opinions over the next guy, nope. Show me the measurements and I'll decide for myself. Its nothing personal but audio can be complicated and getting into the subjective is slippery slope. Just show me the measurements I want to see, cause I know what I want to see there.
View attachment 416147View attachment 416148

The Horizontal polars of the KH420 are pretty good.
View attachment 416149
The stand out driver from ATC is its mid
View attachment 416150

Those are domestic SCM150s which are supposed to be listened to with the grilles on which have the rolled edges built-in (behind the cloth). Take the grilles off and you end up with sharp edges.

The pro versions have no grilles so the rolled-edge is part of the baffle.

 

[dfuller]

I had SCM25s next to my KH310s and aside from some extra sub extension from the KH310, the SCM25s sounded better. Smoother, more revealing of small changes in tone/distortion when loading up plugins (changes in oversampling were extremely audible on the ATCs but not so much on the KH310s). Dynamics more audible too, hearing exactly what a limiter was doing on the ATCs vs the 310s was very revealing.

I ended up buying a pair of SCM50 actives and kept the Neumanns to form an Atmos rig (thinking of selling now as the Atmos market for music is dying thankfully).

FWIW I have compared them like-for-like as well; the 310s are straight up not as good as the 25A mk2. The 310s have a little more low end, but are worse in every other meaningful metric.
- The top end is harsher (the CD waveguide shape in effect shelves the high end up and the tweeter itself is really nothing special where ATC's is quite good and being effectively on a flat baffle means it drops off in the top octave)
- they have way less SPL capability (like, strikingly less - the 310s run out of steam and compress with any substantial volume). I assume this is because the woofer is being asked to do a lot.
- the mids are not as clean (Neumann's mid dome is great, but it only covers maybe 1.5 octaves vs the 3 and change that ATC's covers - and this is easily the biggest concern in the mids, where the 310's sealed box with goofy amounts of linkwitz transform makes the low mid IMD shoot up over 10% at sane levels).
- Oddly enough, the LF/MF dispersion matches better on the ATC - I attribute this to a smaller woofer and about an octave lower crossover point.

But I'd say that they had better be an improvement. They're twice the cost.

I will note that I specified the Mk2, not the original SCM25A. The original has one of the shittiest tweeters I've heard in a professional monitor speaker.

 

[574stereo]

The KH310s are an incredible value for money speaker by the way, I do really like them. The bang-for-your-buck is amazing, but some of the engineering choices make them inferior to the SCM25 for pro use.

As you say, the IMD distortion from the woofer which reaches right up into the vocal band can be a serious problem and the headroom is extremely restricted. The choice of low-end roll-off slope is more to do with marketing than anything else too (or an ill-informed choice from the designer). Looks great on a graph and I'm sure sounds great in an anechoic space but 310s almost always sound totally whack in the lowest octave or so unless you have an exceptionally well-treated space or an anechoic chamber. Directly swapped to SCM25s and a much flatter in-room response but then ended up with 50s.

 

[thewas]

The choice of low-end roll-off slope is more to do with marketing than anything else too (or an ill-informed choice from the designer). Looks great on a graph and I'm sure sounds great in an anechoic space but 310s almost always sound totally whack in the lowest octave or so unless you have an exceptionally well-treated space or an anechoic chamber.

Or have a measurement mic and some PEQ bands, for pro use I rather have more than less bass as negative gain filters make usually less problems than positive gain ones.

 

[dfuller]

Or have a measurement mic and some PEQ bands, for pro use I rather have more than less bass as negative gain filters make usually less problems than positive gain ones.

Personally I view it as "maximal LFX vs low distortion, take your pick" - at least at compact speaker sizes. Once you start getting into speakers that are designed for midfield, that's a different story.


I'd rather a speaker with less extension but better distortion behavior at small sizes - it's... well, not trivial, but not super hard to add and integrate subs.

 

[574stereo]

Or have a measurement mic and some PEQ bands, for pro use I rather have more than less bass as negative gain filters make usually less problems than positive gain ones.

But the speaker already has its own enormous positive gain filter built-in which is causing problems. Headroom, distortion, IMD, very uneven frequency response in most rooms, phase shift, etc. It’d just be better if it wasn’t there in the first place.

And the KH310 doesn’t have built in DSP to correct this (yet).

 

[boxerfan88]

where the 310's sealed box with goofy amounts of linkwitz transform makes the low mid IMD shoot up over 10% at sane levels).

As you say, the IMD distortion from the woofer which reaches right up into the vocal band can be a serious problem and the headroom is extremely restricted.

Does adding a sub crossed at 80Hz help to alleviate the low-mid IMD issue of the KH310?

 

[darakon]

I would say Neumann and ATC follow a little different philosophies.
Neumann follows the classical ideals, which are normally praised here on asr.
The Neumann speaker measure very close to perfect.
I listened to a lot of them and yes, they are good. But I was sometimes missing a bit about Neumann speakers. Maybe they are too perfect to steril.
The ATC's for sure are Studio-Monitors, but with a little audiophile touch.
They don't measure as perfect as Neumann do. The carbinets are not that optimized.
But they score with nice drivers and a little bit more audiophile touch.

 

[thewas]

I'd rather a speaker with less extension but better distortion behavior at small sizes - it's... well, not trivial, but not super hard to add and integrate subs.

Or to EQ the bass.

But the speaker already has its own enormous positive gain filter built-in which is causing problems. Headroom, distortion, IMD, very uneven frequency response in most rooms, phase shift, etc. It’d just be better if it wasn’t there in the first place.

And the KH310 doesn’t have built in DSP to correct this (yet).

My experiences with it in 2 rooms where different, also it has an up to -5 dB bass dip switch filter on the back or someone could combine it with a Neumann sub giving it the DSP options.

 

[Chrise36]

Funny thing for a brand that advertises itself as the studio reference.

Client List | ATC Loudspeakers

atc.audio

It is not?

 

[Chrise36]

Can you explain what you mean by this? Are you implying that distortion is the most important thing in a speaker, with all other audible aspects like frequency response being the remaining 20% by rank of importance?

The ATC midrange dome is nice. It's been tested by itself, including off-axis and distortion, and has good properties. So do many other drivers. A driver doesn't make a speaker.

Many of us are confused by the crossing over of the dome to a 15" woofer. There are some physics, directivity being a major issue. especially crossed over to a 15" woofer. For instance:

ATC-SM75-150

My attempts to cross over a similar sized midrange to a 15" woofer was entirely unsuccessful, and not because of distortion.

Hence the question, how come there is no reasonably complete set of measurements for an expensive speaker that has so much anecdote?

By far the largest variable in my system is the variability in the product that studios make, including within the same release. I definitely need way more that anecdotes and a few measurements of the nice midrange driver. Good measurements tell us about the speaker and how it will sound in various implementations, how it will interact with various rooms, and how amenable it will be to be EQ'ed to a target.

According to Amir:
''I have a draft of a new distortion measurement. It is a level sweep at 500 Hz showing just THD (distortion) but no noise. Why 500 Hz? Research shows that harmonic distortions of 500 Hz have the highest chances of reaching the most sensitive part of our hearing and hence being above threshold of hearing"
So how do you conclude that the only significant parameter in a speaker is the olive score?
Or maybe there could be a little variance in frequency response allowed due to many factors but distortion eg IMD is more important?

 

[dfuller]

Does adding a sub crossed at 80Hz help to alleviate the low-mid IMD issue of the KH310?

Some, but not totally.

 

[DRNNOO]

Does adding a sub crossed at 80Hz help to alleviate the low-mid IMD issue of the KH310

thats not a straight forward answer, first you have to talk about whats the target spl and listening distance. At lower volumes, there are no issues of IMD at all. IF we are talking about wanting linear playback at 95db you'd probably have to cross at ~200hz to keep the upper mid pristine. The thing is crossing at 650hz

 

[goat76]

I'd rather a speaker with less extension but better distortion behavior at small sizes - it's... well, not trivial, but not super hard to add and integrate subs.

I agree with you.

It’s obviously a strong selling point these days with relatively small loudspeakers having ”impressive” low-end extensions reaching lower than what physically seems possible, which it also is as by doing so will unavoidably introduce high levels of distortion.

I find ATCs' way of always keeping the distortion low and instead let the physical size of the speakers dictate the bass extension to be a better approach, as you can always add subwoofers to the system if deeper bass is required.
ATC doesn't even use the port in their ported speakers for lower bass extension, instead, they use the port to further keep the distortion level down as much as possible.



But when it comes to high levels of distortion due to small speakers reaching lower in the bass than what they physically can hadle, what else can you do to keep the level of distortion in check other than just cut off that “impressive” low bass extension away and let a subwoofer (or two) take over the job?

So what is the idea of making that small speaker reach that low if you're just gonna cut away the bass anyway, well, unless you intend to play it at very low volume levels to avoid some of that distortion and compression? I find this a strange way of doing things, and it seems to have more to do with having impressive specifications rather than following real-world physical limitations.

Maybe some people are immune to distortions, or maybe they have rather lackluster listening environments where a low-distortion loudspeaker doesn't make a significant difference anyway.

 

[thewas]

So what is the idea of making that small speaker reach that low if you're just gonna cut away the bass anyway, well, unless you intend to play it at very low volume levels to avoid some of that distortion and compression? I find this a strange way of doing things, and it seems to have more to do with having impressive specifications rather than following real-world physical limitations.

I don't know at which SPL some people listen to music but when I had the KH310 for a few weeks for nearfield listening at home (it is sold from Neumann as a nearfield monitor) it was super clean at levels of 85+ dB at my LP, I have the impression we like to exaggerate.
Also the HD measurements of Amir showed quite an impressive performance considering their size and being not ported.

 

[574stereo]

I don't know at which SPL some people listen to music but when I had the KH310 for a few weeks for nearfield listening at home (it is sold from Neumann as a nearfield monitor) it was super clean at levels of 85+ dB at my LP, I have the impression we like to exaggerate.
Also the HD measurements of Amir showed quite an impressive performance considering their size and being not ported.

When artists are in the room, needing to average ~ 90 dB and peaks of ~ 110-115 dB is very common. Sometimes artists want it loud and you’ll have to go up from there. Also modern music tends to be very bass heavy, just an extra bump of 2-3 dB of low end and those 7” woofers with crazy amounts of EQ start falling apart incredibly quickly.

Also you’re using fully mixed & mastered music to make these judgements. That reduction in dynamic range only generally happens successfully right at the end of the process. With modern music, this tends to mean a dynamic range of 5-7 dB. At the earlier stage of the process you might be looking at 18-20 dB of dynamic range.

KH310s suffer from woofer cone distortion pretty much constantly in all but the smallest rooms. The 150s and 120s all have problems with port chuffing (it’s quite extreme at times). They’re very good speakers which is why I own them but there are many reasons why the ATC products are a more serious tool in the studio.

 

[thewas]

When artists are in the room, needing to average ~ 90 dB and peaks of ~ 110-115 dB is very common. Sometimes artists want it loud and you’ll have to go up from there. Also modern music tends to be very bass heavy, just an extra bump of 2-3 dB of low end and those 7” woofers with crazy amounts of EQ start falling apart incredibly quickly.

Also you’re using fully mixed & mastered music to make these judgements. That reduction in dynamic range only generally happens successfully right at the end of the process. With modern music, this tends to mean a dynamic range of 5-7 dB. At the earlier stage of the process you might be looking at 18-20 dB of dynamic range.

KH310s suffer from woofer cone distortion pretty much constantly in all but the smallest rooms. The 150s and 120s all have problems with port chuffing (it’s quite extreme at times). They’re very good speakers which is why I own them but there are many reasons why the ATC products are a more serious tool in the studio.

The KH310 are not mastering monitors and when deaf artists want to listen loud anyway no mixing is done. Serious mixing is done at an average of 85 dB (there are even regulations in some countries where this is controlled) where in normal rooms and nearfield listening distances they work fine, also since they are tuned anechoically flat usually they exhibit at such placements a significant bass boost which needs to EQed down giving even more SPL reserves.

The KH150 and 120 have some of the top bass performance for their size for compact ported 2-way monitors (like most in this class) and their ports are even optimised to reduce flow noises but in the end the physics can be stretched but not switched off. Also there are no active ATC monitors in those price classes and I also doubt their 2-way sized monitors perform better if both equalised to the same exact bass response.

 

[574stereo]

The KH310 are not mastering monitors and when deaf artists want to listen loud anyway no mixing is done. Serious mixing is done at an average of 85 dB (there are even regulations in some countries where this is controlled) where in normal rooms and nearfield listening distances they work fine, also since they are tuned anechoically flat usually they exhibit at such placements a significant bass boost which needs to EQed down giving even more SPL reserves.

‘Deaf’ artists…? I guess you’re trying to passively imply that the artists and maybe engineers going with them can’t hear the same things that you’re hearing. This isnt exactly great form and IMO quite rude.

During the mixing process I’ll sometimes have to monitor up around 80-85 dB or even higher but spend most of my time around 76 dB. This is part of every mix engineer’s process, or at least all my friends and colleagues who are turning out good work also do the same.

I never said the KH310 was a mastering speaker although they are often used as such. Mastering requires much lower SPLs than mixing.


If you think these SPL requirements are extreme, you should see how speakers get treated on sessions during live drum tracking.

 

[thewas]

‘Deaf’ artists…? I guess you’re trying to passively imply that the artists and maybe engineers going with them can’t hear the same things that you’re hearing. This isnt exactly great form and IMO quite rude.

It is the sad reality as I know quite few of such, especially in 2024 it is a shame that not few professionals still lack the education of unsafe hearing levels and the corresponding injuries.

During the mixing process I’ll sometimes have to monitor up around 80-85 dB or even higher but spend most of my time around 76 dB. This is part of every mix engineer’s process, or at least all my friends and colleagues who are turning out good work also do the same.

And for such work the KH310 work fine in typical rooms and listening distances if the bass is room corrected.

 

[goat76]

I don't know at which SPL some people listen to music but when I had the KH310 for a few weeks for nearfield listening at home (it is sold from Neumann as a nearfield monitor) it was super clean at levels of 85+ dB at my LP, I have the impression we like to exaggerate.
Also the HD measurements of Amir showed quite an impressive performance considering their size and being not ported.

I just want to point out that I wasn't talking about the NH310 in particular when I wrote “that small speaker”, it was just meant in general of small loudspeaker with seemingly way too much low bass extension for their own good. Sorry if it appeared as if I was talking about the NH310.