ATC speakers / Monitors

[goat76]

A few days ago, I made directivity measurements (0 to 90 degrees, gated) of my ATC SCM40 v2, and as expected, there are a bit of disturbance in the crossover region of the midrange driver to tweeter.

The interesting part is that ATC seems to have used that to their advantage, as the amount of directivity mismatch is regaining some of the lost on-axis energy in exactly that crossover frequency area. I know this because a few years ago, I did some small EQ adjustments and raised that area to an on-axis more flat response, but that made the these speakers sound a bit too bright.
I don't see this as a problem, as these speakers already sound perfectly flat in the listening position.

 

[dfuller]

A few days ago, I made directivity measurements (0 to 90 degrees, gated) of my ATC SCM40 v2, and as expected, there are a bit of disturbance in the crossover region of the midrange driver to tweeter.

The interesting part is that ATC seems to have used that to their advantage, as the amount of directivity mismatch is regaining some of the lost on-axis energy in exactly that crossover frequency area. I know this because a few years ago, I did some small EQ adjustments and raised that area to an on-axis more flat response, but that made the these speakers sound a bit too bright.
I don't see this as a problem, as these speakers already sound perfectly flat in the listening position.

They've intentionally made that dip in the response to compensate for the off-axis flare.

It's an old school way to improve the power response, one that is generally better dealt with via dispersion matching.

It isn't as though ATC is unfamiliar with the concept - the mid dome has some dispersion control on it, and the Seas T25CF001 tweeter they used to use has a minor amount of control as well. You wouldn't even need a big guide like on Neumanns or Genelecs, something sized about like a Seas DXT would be enough at the Fc they use.

 

[goat76]

They've intentionally made that dip in the response to compensate for the off-axis flare.

It's an old school way to improve the power response, one that is generally better dealt with via dispersion matching.

It isn't as though ATC is unfamiliar with the concept - the mid dome has some matching. You wouldn't even need a big guide like on Neumanns or Genelecs, something sized about like a Seas DXT would be enough at the Fc they use.

It’s not a ”state of the art” solution, but it works.

I have had some discussions on another fact-based audio forum, and that recessed frequency area have come up. By judging only the on-axis response, people naturally come to the conclusion that these speakers should sound somewhat recessed in that area, but the reality is that they sound totally flat. What should count in the end is the sound that is perceived in the a normal listening position, and that is achieved.

I think ATC knows exactly what they are doing, and there are many other aspects that must be considered when it comes to studio monitors, which are there main focus point. There are things like easily exchangeable drivers, low distortion, and robust constructions. They simply don’t care about small things that doesn’t make a large difference enough in real world use. ”State of the art” solutions is usually mostly used for marketing bragging, anyway, if you look at it from a broader viewpoint.

 

[Pearljam5000]

There's a myth that ATCs are more "musical" and less analytical
Is that true?

 

[goat76]

There's a myth that ATCs are more "musical" and less analytical
Is that true?

Is a myth ever true?

 

[dfuller]

There's a myth that ATCs are more "musical" and less analytical
Is that true?

LOL no. They're maybe a little more laid back than a Gennie but they tend to be very detailed especially in the range the mid driver covers.

 

[Ifrit]

There's a myth that ATCs are more "musical" and less analytical
Is that true?

to me Genelecs are more fatiguing. Or, rather, takes less time to get tired compared to ATCs. That's from about a year experience in one room with 8351s vs 50s next to each other. But Meyer AMIEs are even faster in causing my brain to tell me "shut that noise off!" FWIW.

 

[Pearljam5000]

to me Genelecs are more fatiguing. Or, rather, takes less time to get tired compared to ATCs. That's from about a year experience in one room with 8351s vs 50s next to each other. But Meyer AMIEs are even faster in causing my brain to tell me "shut that noise off!" FWIW.

Fatiguing as in more detailed? Or just bright?

 

[Ifrit]

Fatiguing as in more detailed? Or just bright?

Fatiguing as in getting tired and can’t make decisions/enjoy the music. Level of detail is about the same. HF has nothing to do with it.

 

[thewas]

A few days ago, I made directivity measurements (0 to 90 degrees, gated) of my ATC SCM40 v2, and as expected, there are a bit of disturbance in the crossover region of the midrange driver to tweeter.

Could you post them here, am sure many would be interested.

The interesting part is that ATC seems to have used that to their advantage, as the amount of directivity mismatch is regaining some of the lost on-axis energy in exactly that crossover frequency area. I know this because a few years ago, I did some small EQ adjustments and raised that area to an on-axis more flat response, but that made the these speakers sound a bit too bright.

Such "tricks" are done since more than 50 years from experienced loudspeaker designers when a directivity mismatch was the rule , that's why also single axis measurements are not a good basis for EQ.

 

[goat76]

Could you post them here, am sure many would be interested.

Okay, here you go...

ATC SCM40 v2 Directivity 0 to 90 degrees.

The same measurements, but spread out.

The average directivity response.

 

[dfuller]

This is why I continually say that if they crossed 500hz lower the directivity match would be fine. Look how narrow the pinch at the top of the mid's range is - it only starts being a thing around 3000hz.

 

[thewas]

Instead of crossing it the mid lower would rather wish they had used a larger waveguide on the tweeter which not only matches its directivity to the mid but also reduces the beaming in the last octave.

 

[Pearljam5000]

Why don't all speaker brands use waveguides is beyond me

 

[thewas]

You can also design loudspeakers which don't significantly need them but those designs are quite special and limited.

 

[Blockader]

Why don't all speaker brands use waveguides is beyond me

Waveguides are most impactful in 2-way or 3-way speakers, they may not be as necessary in 4-way or more complex speaker configurations. Especially with Horbach-Keele crossover filters.

 

[Pearljam5000]

Waveguides are most impactful in 2-way or 3-way speakers, they may not be as necessary in 4-way or more complex speaker configurations. Especially with Horbach-Keele crossover filters.

Yeah
But 90% of the speakers are 2-way or 3-way so you're kind of proving my point

 

[goat76]

This is why I continually say that if they crossed 500hz lower the directivity match would be fine. Look how narrow the pinch at the top of the mid's range is - it only starts being a thing around 3000hz.

If you compare the measurements of the SCM40 and the SCM11. What perceived sound differences would you expect, focusing on the overall sound and how that is affected by the directivity matching between drivers?

The crossover points are at 3.5 kHz for the SCM40 and 2.2 kHz for the SCM11. (I know you know that, but for other participants...)

 

[Mart68]

If you compare the measurements of the SCM40 and the SCM11. What perceived sound differences would you expect, focusing on the overall sound and how that is affected by the directivity matching between drivers?

The crossover points are at 3.5 kHz for the SCM40 and 2.2 kHz for the SCM11. (I know you know that, but for other participants...)

View attachment 461665

I'm pretty sure I would not reliably be able to distinguish between them. But then I have no listener training.

 

[EJ3]

I believe that Trained listening is more about being able to describe what you are hearing (as opposed to knowing that you are hearing something but cannot accurately describe what the issue you are hearing is).
It doesn't mean that you don't hear an issue.