Subs for ATC SCM19A

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Subs for ATC SCM19A

Postby highstream » Fri Nov 17, 2017 6:13 pm

Have a pair of SCM19A's driven from a PS Audio Directstream dac via XLR. I think the first question is whether or not it's possible to add subs to this system short of introducing an external crossover? Then if so, which might be good candidates in the 8-10" range for a modest sized living room set up.

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Re: Subs for ATC SCM19A

Postby MattSPL » Sat Nov 18, 2017 1:38 am

Hi highstream,

What’s your budget?
I’d go for the largest sub you can fit.
A JL Audio F110 is a very good 10 inch sub which will add greatly to your scm19’s.

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > 2 x DIY Dayton Audio UM18-22 Sub

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Re: Subs for ATC SCM19A

Postby highstream » Sat Nov 18, 2017 3:45 am

Thanks. While I was thinking more in the REL Ti or SVS SB range, a pair of 110's I would consider used, although they are a physically large for my location (and as heavy as each SCM19A). Their e110 may actually fit better into my system and listening area size.

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Re: Subs for ATC SCM19A

Postby MattSPL » Sat Nov 18, 2017 11:00 am

highstream wrote:Thanks. While I was thinking more in the REL Ti or SVS SB range, a pair of 110's I would consider used, although they are a physically large for my location (and as heavy as each SCM19A). Their e110 may actually fit better into my system and listening area size.


I’m not familiar with the newer Rel subs, but the older ones aren’t a patch on more modern subs in terms of distortion measurements and general performance.
The JL Audio E110 would be very good, 2 even better. The JL Audio’s are equally good at music and movies.

Cheers
Matt
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > 2 x DIY Dayton Audio UM18-22 Sub

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Re: Subs for ATC SCM19A

Postby darrenyeats » Sat Nov 18, 2017 12:46 pm

IMV to integrate subs *properly* is difficult, and to do it transparently more difficult. Matt's on a sub mission - and I respect all enthusiasm for things audio - but I don't have inclination, time or money for that myself. So here's another point of view but of course explore for yourself.

1. Always #1, acoustics. For mo' bass try moving the speakers nearer to the wall behind them - this is not a problem acoustically* since very little mid/top frequencies are thrown directly backward from a box speaker. For bass frequencies, actually SBIR is better with close placement <0.5m than at 0.5-2m - think soffit mounting in studios. (But always leave at least 1m gap from SIDE walls, and if not possible then treat first reflection points [as I do] - side walls ARE a problem for mid/top specular reflection.)
2. If the speakers are simply too small for the room then bigger active speakers are a good approach, but I've no reason to think this applies to you.
3. Never use mo' bass to cover up problems in the rest of the sound. All the sound should be sweet with no need to hide, then the bass will naturally hit. Make sure you've addressed source issues. Note with active speakers the XLR interconnects have long runs near power cables - I can highly recommend Gotham GAC-4/1 which is star quad and double shielded pro cable, another similar cable would be Mogami 2534 though I've not tried that.

*Except there might be value in keeping equipment racks well behind the plane of the baffles - in my room, the equipment is located behind the listening seats!

I used to own an ATC C4 sub but I sold it. For me the active 50s sound better without a sub, yes even the bass is better - I believe my room is the limiting factor.
Last edited by darrenyeats on Mon Nov 27, 2017 12:03 pm, edited 3 times in total.

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Re: Subs for ATC SCM19A

Postby MattSPL » Sat Nov 18, 2017 3:29 pm

Darren is right about it being difficult to properly integrate a Sub into your system. I use REW measurement software and USB microphone and have fully adjustable delays and eq’s.
One very useful benefit of the JL Audio Fathom is its auto EQ that cuts room bass peaks so that the sub doesn’t add to any existing room mode problems.

The hardest part to address is the timing between the speakers and sub, because you can only delay the sub, not the speakers, so if your speakers output reaches you before the sub, the only way to get around this is to move the subcloser to the listener, or add some form of external electronic delay.
If your using a multichannel setup your processor should contain any necessary software to perform delays etc.
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > 2 x DIY Dayton Audio UM18-22 Sub

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Re: Subs for ATC SCM19A

Postby highstream » Sat Nov 18, 2017 7:19 pm

Thanks for your comments. I agree that setting up subs takes a lot of care, with issues and compromises specific to their use. So did setting up the main speakers. After doing my best with the 19A's, I had a couple of guys from a local shop fine tune things (I wasn't off by much). Reading reviewers' discussions of set up of different subs has also given some good ideas. One in particular that stands out for addressing some of what's been posed here is Jonathan Valin's review of the JL Audio e110's in TAS: http://www.theabsolutesound.com/article ... subwoofer/. The main problem I'll face bringing in subs, and perhaps ultimately an obstacle, will be room layout, which puts the main listening position 8' out on a sofa down a side wall, and a limited amount of space behind with all the cables. So there won't be any trying to force something that doesn't work. I can live with the 19A's as is.

Btw, since it was mentioned, the current system is...
PS Audio PowerBase/Conditioner
PS Audio P5 Regenerator
Oppo 203 with VanityHD audio card
PS Audio Directstream dac
ATC SCM19A active speakers
MG Audio Design AG2S2 XLR
PS Audio AC-12 power cords
Furutech GTX-D NCF(R) outlet
Power fuses: SR Black, Audio Magic Super Beeswax
Samsung 46" F8000 HDTV (cable) in the middle

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Re: Subs for ATC SCM19A

Postby peter964rs » Sat Nov 18, 2017 7:28 pm

Hi

I use twin BK electronics xls200 which I'm very happy with.

Bk used to mfr REL subs many years ago on an OEM basis and I was very happy with the quality of these two subs for a great price. They also nicely match my scm50asl in cherry.

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Re: Subs for ATC SCM19A

Postby highstream » Sat Nov 18, 2017 8:15 pm

Thanks for the suggestion. The BK has two things going against it for me: I'm in the States and it uses the Neutrik Speakon connection for the high level input (REL does the same), which rules out the Directstream dac. The dac would need to use the low-level inputs via RCA's. Using the high level input is preferred, with XLR being a little easier setup with the DSD. I'm also guessing that splitting the XLR signal vs. running RCA's would sound better - Neutrik makes an XLR splitter - although that is just a guess without having tested.

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Re: Subs for ATC SCM19A

Postby highstream » Mon Nov 27, 2017 3:07 am

As I look at good subs for the SCM19A that don't require a Speakon connection, as REL's do, but instead use RCA inputs/outputs, I have a few questions:

- Does an XLR cable from the dac's XLR output lose its balanced nature when an RCA adapter is used at the sub?

- Does the unbalanced signal from the sub's output remain unbalanced to the ATC even if an XLR cable is used (with an adapter at the sub)?

- Is it likely that noise will be introduced in using the XLR cables and RCA adapters?

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Re: Subs for ATC SCM19A

Postby Brad Lunde » Tue Nov 28, 2017 4:28 am

highstream wrote:As I look at good subs for the SCM19A that don't require a Speakon connection, as REL's do, but instead use RCA inputs/outputs, I have a few questions:

- Does an XLR cable from the dac's XLR output lose its balanced nature when an RCA adapter is used at the sub?

- Does the unbalanced signal from the sub's output remain unbalanced to the ATC even if an XLR cable is used (with an adapter at the sub)?

- Is it likely that noise will be introduced in using the XLR cables and RCA adapters?


Question 1) yes- you need three connections for balance (hot, negative and ground)
Question 2) yes- any unbalanced portion of the cable run stays unbalanced. Once noise hits the unbalanced cable (shield and negative are tied together in unbalanced cable) it comes directly into the audio input and viola- noise in everything thereafter.
Question 3) No, but impossible to say. The advantage of balanced is the shield carries all the noise hitting the cable (like RF) and dumps it to ground before it goes to audio inputs. The plus and minus connectors are shielded, and the shield does not go to audio. So if you are in high RF environment or a place where magnetic noise is high, unbalanced will be a nightmare and impossible to solve. That's why studios use balanced lines only- who wants to risk the best take on random noise? Some caveats are that some shielded (balanced or XLR) cable is not fully shielded! Usually a cheap balanced XLR cable uses a partial coverage spiral shield, with gaps of coverage, places where no shield is covering the negative or positive and this type of cable is not quiet. The goal with balanced line is to completely cover the two audio lines inside a shield and lower the noise floor.

brad
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

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Re: Subs for ATC SCM19A

Postby highstream » Tue Nov 28, 2017 7:32 am

Thanks Brad. As I suspected. Whether or not I end up with an RCA IC between Directstream and sub, I suspect the trickiest part will be going from the sub (RCA output) to the 19A's. The engineer at JL Audio suggested that an active RCA to XLR adapter might be necessary, although I'm not sure if that means a box or something like the Neutrik miniature transformer (a male RCA would still be needed) - https://www.markertek.com/product/na2m- ... lack-coded.

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Re: Subs for ATC SCM19A

Postby Brad Lunde » Fri Dec 01, 2017 6:14 pm

highstream wrote:Thanks Brad. As I suspected. Whether or not I end up with an RCA IC between Directstream and sub, I suspect the trickiest part will be going from the sub (RCA output) to the 19A's. The engineer at JL Audio suggested that an active RCA to XLR adapter might be necessary, although I'm not sure if that means a box or something like the Neutrik miniature transformer (a male RCA would still be needed) - https://www.markertek.com/product/na2m- ... lack-coded.


I run a unbalanced RCA cable to XLR input in hi fi regularly. Especially with subs. I rarely have a problem and I would not be afraid of doing that- just get a RCA to XLR cable. Buy a lower cost one and see if there is noise where you are. If you live in dense city, or near a lot of transmitters, there might be more reason for concern. Transformers or active level matching devices change the sound too much. ALL of them. You can hear those devices easily on an ATC!

Brad
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Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

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Re: Subs for ATC SCM19A

Postby highstream » Fri Dec 01, 2017 8:56 pm

Thanks Brad. Instead of buying mixed end cables, I discovered some longer Best Buy quality XLO RCA's from the 1990s in my extras box, and stuck a couple of RCA/XLR adapters at the 19A's. They turned out to be quieter than my current MG Audio XLRs (which are unshielded, but have a little extra something for RFI rejection). I don't have subs yet, but it would save $$ if my XLR cables could be used in both runs (and the dac's XLR output), so I just ordered some Neutrik RCA male to XLR female adapters. I can't imagine that either of these adapter tests would come out much different than your idea of testing with a mixed end cable.

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Re: Subs for ATC SCM19A

Postby Brad Lunde » Tue Dec 05, 2017 6:15 pm

highstream wrote:Thanks Brad. Instead of buying mixed end cables, I discovered some longer Best Buy quality XLO RCA's from the 1990s in my extras box, and stuck a couple of RCA/XLR adapters at the 19A's. They turned out to be quieter than my current MG Audio XLRs (which are unshielded, but have a little extra something for RFI rejection). I don't have subs yet, but it would save $$ if my XLR cables could be used in both runs (and the dac's XLR output), so I just ordered some Neutrik RCA male to XLR female adapters. I can't imagine that either of these adapter tests would come out much different than your idea of testing with a mixed end cable.


Sounds like a good solution.
Brad Lunde
Lone Mountain Audio, part of TransAudio Group
ATC Importers USA

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