SCM19 vs SCM20PSL vs SCM40

[Bulldog]

QLM:

More information, that might be irrelevant to you. I've reviewed and owned powered ATCs over a long time. My experience, if you go that path, is that the preamp is really important to getting a satisfying sound. While ATC seem like a natural choice, the there are other brands that will be terrific and slightly different sounding, e.g. E.A.R. and Pass Labs (XP12). Just FYI.

... and RME

My RME ADI2 DAC/Pre is brilliant with my SCM150asl speakers.

[Gandalf]

This may be of interest a recent (2022) review of ATC SCM40 passive speakers by Soundstage Ultra where the reviewer also reviewed SCM 20 speakers a decade ago. At the end of the review the reviewer states ' and I bought them' but I am not sure whether his purchase were ATC SCM40's or ATC SCM 20's...?
https://www.soundstageultra.com/inde...0soundstaging.

[Bulldog]

From my reading of Mr Gorse's review, I would say he purchased the SCM40s

[QuiteLikesMusic]

Would the SCM19a's be an option? You don't need a stand, or an amplifier. A simple preamp will do the trick. Single ended (rca) preamp output is okay, but balanced is better. I haven''t heard the SCM119a's in a smaller room, but they should be easier to integrate than a pair of SCM40's.

Hi Bulldog , I've been reviewing the comments as I'm edging towards the active 19s, following your suggestion. I noticed you suggested that an RCA preamp could feed them. Is this possible, when ATC actives taken balanced XLR? I've done a web search and there's not much offered in terms of RCA to XLR interconnects. If this is a route, then my existing integrated amp has an RCA pre-amp output. Though, saying that, the thought of having a new ATC preamp feed an ATC active 19 is a very tempting thought.

[saureign]

I've done a web search and there's not much offered in terms of RCA to XLR interconnects. If this is a route, then my existing integrated amp has an RCA pre-amp output. Though, saying that, the thought of having a new ATC preamp feed an ATC active 19 is a very tempting thought.

https://www.audiophonics.fr/en/xlr-r...ter-p-992.html

[jophill]

Hi Bulldog , I've been reviewing the comments as I'm edging towards the active 19s, following your suggestion. I noticed you suggested that an RCA preamp could feed them. Is this possible, when ATC actives taken balanced XLR? I've done a web search and there's not much offered in terms of RCA to XLR interconnects. If this is a route, then my existing integrated amp has an RCA pre-amp output. Though, saying that, the thought of having a new ATC preamp feed an ATC active 19 is a very tempting thought.

Connecting the RCA preamp output to the XLR ATC input is no big technical problem in principle [1].

A couple of long RCA leads (which normally have male connectors) and a couple of RCA female to XLR male adaptors will probably do fine in a domestic situation although these will lose the protection from interference of a balanced cable. This is normally no problem at home. I think the adaptors saureign links to are RCA male to XLR male so I think NEUTRIK NA2MPMF XLR Male - RCA Female Adaptor - Audiophonics is the right one (but I always have to think at least three times when getting adaptors - it's so easy to make a mistake).

The "studio" way of doing the RCA->XLR connection without a proper audio isolation transformer would be cable 17 here: RANE Commercial - Knowledge Base. A pair of these cables from designacable designacable NYS373-0-VDINBK0400-NC3MXX-B 4m RCA to Male XLR Cable - Black : Amazon.co.uk: Electronics & Photo are probably wired that way but they don't actually reveal this.

[1] A differential XLR input responds to the voltage difference between the connector's hot pin and its cold pin. You normally make these +signal and -signal from a proper differential XLR output; but it's no problem with +signal and zero (ground) from an single-ended RCA output. You will note that typically you get half the signal into the XLR input. However, the ATC amp packs have more than enough gain, although you will have to turn up the volume control a bit.

[jophill]

... but now having thought again, the adaptors saureign proposes will work at the preamp end of the link with a normal XLR female to XLR male cable to the loudspeaker. That would be preferable to my proposal as long as the RCA to XLR adaptor and the XLR cable don't put too much strain on what are often weak RCA sockets.

[QuiteLikesMusic]

jophill, I never thanked you for your more than generous post regarding RCA => XLR cabling. It must have taken you some time to put together.

I'm currently still in my research phase, but getting progressively closer to a lengthy listening session at my local dealer. If I don't take the active 40s with one of the dealer's ~£2k pre-amps (ATC, Hegel, Bel Canto) I would be surprised. I might even keep my 20yo Musical Fidelity integrated for its pre-amp output.

Given your previous post, can I ask question in this same area? I noticed, while looking at the specs on the ATC site of the active 40s and their CA2 pre-amp, that the 40s take balanced XLR, yet the pre-amp only offers unbalanced XLR output. This surprised me a little. Is it a biggie?

[saureign]

I noticed, while looking at the specs on the ATC site of the active 40s and their CA2 pre-amp, that the 40s take balanced XLR, yet the pre-amp only offers unbalanced XLR output. This surprised me a little. Is it a biggie?

Not true. CA2 has balanced output
https://atc.audio/wp-content/uploads...2-Mk2-Rear.png

[QuiteLikesMusic]

Also, can anyone tell me if the footers, which extend sideways from the plinths of the active 19s and 40s, are removable? If they are, is it still possible to affix spikes beneath the front of the plinth?

[QuiteLikesMusic]

Not true. CA2 has balanced output
https://atc.audio/wp-content/uploads...2-Mk2-Rear.png

Maybe an error on the ATC site then: https://atc.audio/hi-fi/electronics/amplifiers/pre/ca2/

Analogue Preamp Outputs: 2 x stereo pair RCA/Phono, 1 x stereo pair male XLR (all unbalanced)

And this is from its manual:

Connections to the main output may be from RCA phono plugs or XLR plugs. Connections to the XLR output sockets follow the convention of pin 1 to ground, pin 2 to signal “hot” and pin 3 to signal return (signal ground). When connecting to equipment with XLR (balanced) inputs, the connectors should be wired pin for pin (i.e. 1 to 1, 2 to 2, and 3 to 3). Diagram 3 illustrates the XLR output pin arrangement. Diagram 4 illustrates the cable arrangement for connection to balanced inputs

Clearly, this is not an area I understand at all well.

[saureign]

I hear you. Now, with your quotations, I am confused, too...

[QuiteLikesMusic]

I've emailed ATC. I'll post when I get a reply. I'm hoping they'll offer me a free pair of active 40s in thanks for pointing out their mistake

[Nikhil]

The CA2 appears to have one balanced output from the rear image shown on the ATC website.

[saureign]

yes, yes, but QLM was worried that those output are not real balanced inside

[QuiteLikesMusic]

The CA2 appears to have one balanced output from the rear image shown on the ATC website.

Do XLR outputs necessarily have to be balanced? I'm not disputing that the CA2 has XLR outputs, but are they balanced?

If the CA2 is ATC's preferred offering for feeding their Entry series of active speakers then it seems odd it's not also offering balanced.

[Nikhil]

Do XLR outputs necessarily have to be balanced? I'm not disputing that the CA2 has XLR outputs, but are they balanced?

https://atc.audio/wp-content/uploads...0821-Web-1.pdf

No they are not. Sloppy work on my part - XLR outputs need not be truly balanced.
As per page 6 of the ATC Electronics brochure - all analog outputs of the CA2 including the XLR output are unbalanced.





.

[jophill]

Do XLR outputs necessarily have to be balanced? I'm not disputing that the CA2 has XLR outputs, but are they balanced?

If the CA2 is ATC's preferred offering for feeding their Entry series of active speakers then it seems odd it's not also offering balanced.

I suspect the normal consumer-world mix-up between "balanced" and "differential" is happening here but only ATC can clarify for sure. I suspect the connection offered from the CA2 over XLR to an active ATC loudspeaker is balanced but is not differential. If so, you still get all of the XLR noise rejection advantages.

However, in the home environment there's very rarely any practical issue about any type of good quality interconnect. In the studio with lots of other gear around and lots of electrical noise - yes it often matters - but at home mostly there's no problem. So I think it's not really necessary to worry anyway.

The CA2 "unbalanced" specification is not too odd to me. They are probably deliberately using it in the way most consumers understand. But to explain I have to get fairly technical. Ignore the rest if the explanation does not matter.

As I wrote, there's a common consumer-world mix-up between the technical meaning of the terms "differential" and "balanced". An XLR connection does not have to be either balanced or differential.

Differential sources put +signal and -signal onto the "hot" and "cold" pins of an XLR connector (ground is separate). You can put a single-ended (opposite of differential) source's +signal and ground onto the hot and cold pins too. Because the signal is the difference between the two pins, a differential receiver will see twice the signal level from a differential source - and that's good because it keeps the signal further above noise levels. I have a suspicion that ATC are using the term "unbalanced" in their consumer literature on the CA2 to mean this.

Balanced connections have the same impedance from hot pin to ground and cold pin to ground. This means that any external interference gets coupled equally to both pins, and a differential receiver cancels this noise because the difference is zero. Even if you put a single-ended signal onto a balanced connection you will get this noise cancellation. And the differential receiver on an ATC active loudspeaker is very good at doing this cancellation. It gets tweaked in the factory for maximum noise rejection.

The explanation may possibly be too confusing. It may fall under Blaise Pascal's "I'm sorry this letter is so long but I didn't have the time to make it shorter". If so, sorry.

[QuiteLikesMusic]

Reply from ATC regarding my XLR question

.Thank you for your enquiry and for your interest in ATC products.
While it may seem counterintuitive, this is not an error - the CA2 does feature unbalanced XLR output only. A fully balanced output is offered only on the SCA2.
This configuration is actually very satisfactory, certainly for the shorter cable runs encountered in domestic settings. An XLR cable of standard wiring can be used to make the connection, and a useful degree of hum and noise rejection will still be achieved.
Despite this apparent mismatch, then, the CA2 was actually designed to partner the SCM19 and 40 (and their stablemates) and does so very well.

[Verlin]

Mark: I just happened onto this forum today and noticed your post. I have SCM 40s version two passives and I drive them with a musical fidelity a 308, and it seems to be a match made in heaven. Even more coincidently, my name is also Marc, albeit spelled differently. Best of luck to you.

[QuiteLikesMusic]

Mark: I just happened onto this forum today and noticed your post. I have SCM 40s version two passives and I drive them with a musical fidelity a 308, and it seems to be a match made in heaven. Even more coincidently, my name is also Marc, albeit spelled differently. Best of luck to you.

Hi Verlin. That's good to hear as I'm currently steering towards keeping my amp and going for passives.
Can I ask a couple? Have you had the amp overhauled or upgraded? It's been advised to me as a necessary thing to do, especially as it might take £4-5k just to "stand still" if I bought a new amp.
Also, what speaker cables are you using?

Ta

[Verlin]

I haven’t done anything to the amp since it seems to work fine and the idea that it might need work is purely conceptual to me at this point. The remote stopped working, or some of the functions did, and I found an inexpensive substitute online that had been programmed for the amp. Other than that, no problems. I don’t have fancy cables, just audio quest forest or the equivalent throughout my system. I’ve never had the opportunity to hear expensive ones and the idea of spending a lot of money on cables doesn’t appeal to me.
To be honest, I haven’t heard a lot of audiophile systems to be able to compare what I’ve got to alternatives, but after a lot of research and a lot of listening, I can certainly tell you I am very happy with the musical fidelity amp. And probably even happier with the speakers. They are wonderful.