ATC SCM50 PSL Passive HiFi Speakers & ATC P2 Power Amplifier Review
ATC SCM50 PSL passive hifi speakers p2 power amplifier review website 1

Interesting Beginnings 

I have always been intrigued by Studio Speakers, are they better than HiFi speakers, are they less compromised and would I prefer the sound? I began speaking to ATC Loudspeakers about this because they are a UK based manufacturer of both and if anyone could answer this question it was them; but instead they posed a different question; which is better an active or a passive speaker because again they manufacture both.

I will admit I have never really been taken with the idea of active speakers, I have always had a problem with someone else choosing the amplifiers for me, of course they wouldn’t use amplifiers I would choose creating a sound that I want, well this turned out to be one of the biggest turnaround opinions of my HiFi life but more on that later.

I was very keen on spending time with the ATC SCM50, a speaker first designed in the mid 1980’s, updated over the years its still a highly revered speaker for good reason.  ATC sent me the P2 to use with the SCM50, its their most powerful standalone stereo power amplifier and the excitement began.

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First Impressions

There is no getting away from the form factor, the SCM50 is a very traditional looking speaker with a rectangle cabinet that sits on a metal frame stand but I think its still pretty unique and very stand out, you know its an ATC even from just a quick glance. I am definitely warming to this speaker form factor and earlier in the year I reviewed the Wharfedale Linton Heritage  with a similar-ish form factor and I liked them as well.

One thing that wont grow on me is moving the SCM50 around, they are much heavier than they look 41.1kg and the cabinet is not as tap on the side inert as I was expecting,  meaning the weight must predominantly be coming from the speaker drivers and crossover. ATC make all their own speakers drivers and most of the crossover components in house in the factory in the UK and there are only a handful of speaker manufacturers that still do this so its very praise worthy.

The stand out driver in the SCM50 is the 75mm soft dome midrange, a driver design only used by a limited number of speaker manufacturers, ATC, PMC and now Wharfedale are the only ones I can think of.

Interestingly the mid range driver is the acoustic centre of the speaker and that is important to consider for setup. ATC suggest to put yourself and the SCM50 in an equilateral triangle or as close as you can, with toe set the SCM50 to cross paths just behind the listening position. Most importantly they suggest adjusting the spikes on the stands so that the rear spikes are set shortest and the front spikes are long putting the SCM50 at a slight angle up towards the listener. I found this made a big difference to the scale and soundstage overall space and its not something I would have thought to do – Super Pro Tip there for you.

One thing I did struggle with a little was making fine movement adjustments for the best positioning on the stands. ATC had installed a rubber gasket on the top of the speakers stands and the SCM50 gripped and stuck to the stand which is great in one regard because as the Spice Girls would say when two become one but being stuck makes it hard to make those very fine adjustments for that perfect locking into focus sound.

Luckily it was fairly easy to get the SCM50 to sound about right and by that I mean creating an even sound stage from left to right with a solid centre image, I am very susceptible to slight time differences of speakers in my room and find distance and really fine tuning of distance / time alignment extremely important and quite finicky. I set the speakers the best I could and used them to review several other products. There were some instant standout things about the SCM50 that were impressive but it wasn’t until I measured them and fully dialled them into my room with a custom Dirac Live calibration that I truly heard what this speaker and amplifier combo can do.

If you look at the in my room frequency response you can maybe see why that is, I was very carful not to mess with the SCM50’s natural in room response for the upper mids and highs but I better balanced the rooms negative effects on the mid range and bass to create a nice full and full range sound utilising the room gain to get bass down to approx 30hz and below. This is not a common bass response for the SCM50 if you had them placed out into a much larger room you would expect to see bass rolling off from around 50hz, ATC confirmed this to me.

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To dial in the custom Dirac Live calibration curve for the SCM50 was easy, it took me about 10 minutes and only 3 attempts to nail it and get a sound that I think is just about faultless, please see the sound demo video below for an idea of what I mean.

Sound Quality

Remember I am referring to both the SCM50 and the P2 power amplifier when referring to sound, I was unable to separate them and what they do individually, they were reviewed very much as a duo.


I think most people would assume the star of the SCM50 would be the 75mm soft dome midrange driver but I actually found the tweeter, or really the treble balance to be the most stand out impressive thing. Most speakers at this kind of money do great mid range but not many that I have reviewed have delivered treble like the SCM50 P2 pairing. For me it’s a perfect blend of crispness and sharpness without being over bearing or glary. I find with a lot of speakers the treble can be too laid back and not present enough when you factor in the kind of bass I look to achieve for a “balanced sound” and my room conditions being very heavily acoustically treated.  The tweeter is called the SH25-76S and its a dual suspension design with more detail, being available here

Interestingly looking at the in room frequency measurements the treble is nicely extended but its not exaggerated or raised like we might see in a Bowers & Wilkins speaker and yet the treble is there, all the time there with subtleties and details that are always present and at times treble detail can appear from nowhere catching you out, but in a good way. These treble intricacies are presented that bit clearer and better resolved than on many other speakers I have listened to.

If you are used to a treble delivery from other speaker driver technologies such as ribbons or AMT the SCM50 treble does sound like the treble from a dome tweeter, its not as effortless sounding as an AMT for example but its precise, on point and for most part transparent, free of the speakers and its the energy in the treble that keeps the speaker sounding snappy.

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With how I had the speakers positioned in my room and the Custom Dirac Live calibration I set the SCM50 / P2 to deliver a nice and big, solid and full sounding bass with excellent timing, rhythm and smoothness. It was bass that flowed like water with an elastic bouncy character, serious but also fun. I listened to more dance music because of the bass, it had an old school nostalgic nightclub listening to vinyl bounce to it, bass that’s cuddling you as you listen but its faultless bass that’s fast and on point. Change the track to something else entirely like some jazz and the bass character becomes tight, detailed and instrumental.

It’s the ATC combo’s ability to do both of these so well that really impressed me and the bass has a real "woody" like character, its not ultra precise clinical sounding bass notes there is a rounded flow to them with never a stressed or strained sounding note. Its an always effortless sounding bass and maybe that is the larger 9 inch bass drivers being more more at ease than say 2 x 6 inch doing the same thing, or maybe its just the quality of the driver.

Mid Range / Vocals

The midrange and vocal delivery from the SCM50 is a very interesting one because I feel that other speakers present their vocals with a tighter and more focused sound, like KEF’s Reference 3 for example. The Reference 3 can, depending on the system and setup sound ultra tight and focused in their vocals delivery and initially this seemed missing from the ATC. However after a longer listen the more relaxed sounding vocals from the SCM50 have an ease about them which subjectively some Audiophiles may feel sound more natural, free, expressive and a little less like a speaker. There is bags of detail present the mid range and I didn’t feel wanting for anymore.


Soundstage was interesting because the ATC combo I think sounded the most like headphones from any speaker / amp combo I have reviewed so far, and by that I mean they sounded very monitor in style. Maybe the studio heritage is showing here. Obviously this could be my room or the fact I was using the Chord Hugo TT2 as a DAC and Pre Amplifier, its possible using a dedicated pre would change this but using the TT2 with other speakers they have created a sense of a more separated and spacious soundstage. I think the SCM50 sound organised and honest with everything being where it should in the soundstage without exaggeration.

I really enjoyed the sense of space in the middle of the soundstage, it didn’t matter how complex the music there was never any hardening or compressing of the sound and I was expecting it to at times but back to what I said about the bass the water like flow well that is how the SCM50 and P2 roll – they take it all in their stride and never sound over worked.

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What About Negatives.

For sound I cant think of any, that doesn’t mean this pairing sound perfect or will be ideal for everyone, but for how I had them setup and for what I am looking for I cant think of any negatives, genuinely.

I did notice that the SCM50 seem to be a speaker that comes to life more when you turn them up, or maybe its the power they want. They still sound fine at lower volumes but a little less special.  I think their setup is very important to get right, when is it not, but the SCM50 are not a naturally warm sounding speaker, warmer sounding speakers are often easier to get a pleasing result from.

The looks are not going to be for everyone and you can buy much prettier speakers for this kind of money but there is a certain something about how the SCM50 look in the flesh,  you will find yourself taking them very seriously I can assure you of that.

The SCM50 the only speakers I have reviewed that are tri-wire or tri-amp capable and if you use matching speaker cable jumper links then your going to need to buy and extra set.

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Final Thoughts

If this was a home demo period rather than a review I could see myself wanting to buy both the speakers and the amplifier, I have even had a tape measure out to see if I could fit one of the ATC centre speakers into my space, you could say they have made that much of a positive impression on me. I would really like to give a full ATC speaker system a whirl for home cinema because I think all the positive traits I have enjoyed for music would make them ideal for home cinema sound too.

Interestingly coming back to where I started the review the ATC P2 and SCM50 combination is what I really liked but that doesn’t mean you have to buy this amplifier with the speakers for great results however I would suggest it as a great place to start if you are planning a listen for yourself.

This in a way could be the end but its actually where things become a even more interesting because ATC are now going to convert this exact pair of SCM50 speakers from passive to active which means there will be 3 ATC amplifiers per speaker one dedicated to treble, one mid and one bass and the passive crossovers get replaced for active ones and that is where it all changed, literally.

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Drivers: HF 25mm Mid 75mm LF 234mm Super Linear
Frequency Response -6dB: 40Hz & 25kHz
Matched Response: ±0.5dB
Sensitivity (sine wave): 85dB @ 1W @ 1m
Max continuous SPL @1m: 112dB SPL
Crossover Frequency: 380Hz & 3.5kHz
Input Connector: Binding Posts/4mm banana plugs
Recommended Power Amplifier: 100 to 1500 Watts
Nominal Impedance: 8 ohms (5.5 ohm minimum)
Cabinet Dimensions(HxWxD): 717 x 304 x 425mm (stands add 250mm to height)
Weight: 41.1kg