Adding a sub to the stereo, question

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Re: Adding a sub to the stereo, question

Postby MattSPL » Fri Jan 06, 2017 10:00 pm

ledcam wrote:We're very happy with it. Since buying the price for the Sub 2 seems to have doubled which is a good argument for just having one :D

We had two B&W 850s at one point a few years ago. I know two subs are often recommended but in truth I didn't notice a significant detriment when we reverted to one. Possibly the room dimensions. We didn't find the B&W easy to tune to the room.

The Paradigm is such a different beastie altogether. Much more adaptable and the kit which comes with it allows you to custom fit it to your room. A very impressive performer. Our current listening room wouldn't call for two subs but maybe in a larger room. The dealer we bought from has two other clients with two Sub 2s - one guy lives in a flat so no idea how his neighbours feel about that. We find particularly when playing a bluray that quite often things on the walls move about. It really goes low - love it. Without a doubt the best sub we have ever owned.


It's certainly an impressive beast :D
There's one for sale at a local Hifi shop for €4k, which sounds like a bargain to me :)
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: Adding a sub to the stereo, question

Postby tw99 » Sun Jan 08, 2017 4:28 pm

I've got a (single) C1 sub to go with my SCM40s (original model). It doesn't do anything at all for the neutral bass balance that's common across the whole ATC range. All it does is fill in below 50Hz where the main speakers roll off. It's quite surprising in fact how little it does on most tracks, so I'd say you may need to think again if you're looking for More Bass.

I use the room curve feature on my Dspeaker corection device to slightly boost the levels below 100Hz, this works well for me to give a slightly weightier presentation.
NACD3.5 | SBT / DSpeaker anti-mode 2.0 / SIA2-150 / SCM40 + C1

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Re: Adding a sub to the stereo, question

Postby darrenyeats » Sun Jan 08, 2017 7:27 pm

I think a sub in the room can affect the bass of the mains. Before I sold the C4 it was switched off for months. When I moved the C4 out of the room, that was the day the 50s bass got better. I think the sub acts as a passive absorber around the resonant frequency of the sub. You might indeed prefer to have a sub - I accept this - but doing A/B comparisons simply by switching the sub on/off is NOT a good way to decide!

I use Helmholtz resonators and they have to be tuned precisely to get the best out of them. These absorb room resonances in a narrow band, and it's the discontinuities in resonance time that are most offensive. You'd have to be extraordinarily lucky for a switched off sub to help your bass acoustics overall, it certainly didn't in my case.

When you get a bigger main loudspeaker, you're getting a bigger dynamic envelope. This includes not simply frequency response but also impulse response (since the resonant frequency is lower, if ported so is the port tuning) and dynamic headroom. You don't get the same effect by tacking on a sub.

Yes, this is a topic that leads to strong opinions, ha-ha!

But before even thinking about bigger speakers or a sub, first consider these!
1. Speaker or listener positioning - there is relatively little problem with pushing speakers nearer to the wall behind them, if you need to go near side walls then treat first reflection points!
2. Bass is never perceived in isolation; sometimes it's tempting to attack a problem in the mid/upper frequencies by covering it up with mo' bass. Maybe you need to address room acoustics or front end or whatever instead, in terms of overall sound.

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Re: Adding a sub to the stereo, question

Postby MattSPL » Sun Jan 08, 2017 9:02 pm

darrenyeats wrote:I think a sub in the room can affect the bass of the mains. Before I sold the C4 it was switched off for months. When I moved the C4 out of the room, that was the day the 50s bass got better. I think the sub acts as a passive absorber around the resonant frequency of the sub. You might indeed prefer to have a sub - I accept this - but doing A/B comparisons simply by switching the sub on/off is NOT a good way to decide!

I use Helmholtz resonators and they have to be tuned precisely to get the best out of them. These absorb room resonances in a narrow band, and it's the discontinuities in resonance time that are most offensive. You'd have to be extraordinarily lucky for a switched off sub to help your bass acoustics overall, it certainly didn't in my case.

When you get a bigger main loudspeaker, you're getting a bigger dynamic envelope. This includes not simply frequency response but also impulse response (since the resonant frequency is lower, if ported so is the port tuning) and dynamic headroom. You don't get the same effect by tacking on a sub.

Yes, this is a topic that leads to strong opinions, ha-ha!

But before even thinking about bigger speakers or a sub, first consider these!
1. Speaker or listener positioning - there is relatively little problem with pushing speakers nearer to the wall behind them, if you need to go near side walls then treat first reflection points!
2. Bass is never perceived in isolation; sometimes it's tempting to attack a problem in the mid/upper frequencies by covering it up with mo' bass. Maybe you need to address room acoustics or front end or whatever instead, in terms of overall sound.


Interesting observations about the sub in the room absorbing bass.

Your right about adding a sub not being the same as a pair of large speakers, the only way to properly achieve this is by running a high pass filter on the mains and letting the sub play higher, but you need 2 subs to do this placed beside the mains, or bass will become localised.
The only way to run a single sub successfully is speakers full range and sub crossed over very low with a steep crossover.
Sony BDP-S790 > Matrix Quattro Dac > Digidesign RM2's with SB Acoustics drivers > DIY Dayton Audio UM18-22 Sub

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Re: Adding a sub to the stereo, question

Postby scm100 » Tue Jan 10, 2017 10:14 am

I'm using two ATC C4 subwoofers with my Scm100 asl.
They are set up as stereo subs and are very easy to integrate with the 100's , which are ran full range as recommended by ATC.

I've had a lot of subs over the years including the top of the line REL Studio and never been happy with any of them .
But the ATC C4 are in different league to every other sub I've owned.

I have them set up fairly close to each main speaker and around 1200mm out from the front wall , they are very clean and tight sounding adding more depth , spaciousness and well defined tight low frequencies.
Set up properly they are amazing and a significant improvement over just using the 100asl.
ATC SM100 ASL PRO , SCM20 ASL PRO MK2 , Two ATC C4 SCM 0.1/12 Subwoofers.
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Re: Adding a sub to the stereo, question

Postby linger63 » Tue Jan 10, 2017 12:12 pm

scm100 wrote:I'm using two ATC C4 subwoofers with my Scm100 asl.
They are set up as stereo subs and are very easy to integrate with the 100's , which are ran full range as recommended by ATC.

I've had a lot of subs over the years including the top of the line REL Studio and never been happy with any of them .
But the ATC C4 are in different league to every other sub I've owned.

I have them set up fairly close to each main speaker and around 1200mm out from the front wall , they are very clean and tight sounding adding more depth , spaciousness and well defined tight low frequencies.
Set up properly they are amazing and a significant improvement over just using the 100asl.


Hi,

I am considering integrating my 2 Velodyne HGS 15" Subs currently used for HT into my stereo system partnering SCM 70's.(9"bass driver)
They are a sealed unit and produce very tight bass with low distortion capable of high SPL's

I am wondering how you addressed phase and time alignment issues and whether you are using DSP/Room EQ or not re crossover/volume settings?.........
Did you dial in one C4 at a time or treat them as a stereo pair?.......
How exactly are they connected to your system?.........
Regarding placement .......I am limited to behind and outside the Mains in each front corner of the room (which works well for HT although Audyssey XT32 Room EQ definitely helps!!!)

I plan on using a Benchmark DAC2 DAC/PRE which has XLR (currently going to the SCM 70's) and RCA outputs.

I also want to achieve similar to what you did regarding running the Mains full range and just letting the subs fill in the missing lower register (s)
Hoping you have some tips for me!!!
TIA.

Cheers,

John

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Re: Adding a sub to the stereo, question

Postby scm100 » Wed Jan 11, 2017 10:43 am

I'm not familiar with those velodyne subs but ATC C4 subs use the same very low distortion SL spec 12" drivers as the SCM100ASL , coupled to a 650 watt continuous output amp.
They are built to match with ATC speakers and have the same exceptional sound and build quality .

They sell in a gloss paint , beech or black ash finish for around 6000 pounds each .....$15,880 AUD each in Australia.
Expensive , but not overpriced for how they perform.

I don't use any eq , have the SCM100ASL connected to the xlr outputs of my bel canto pre 6 gen2 preamp and they run full range , the subs are connected to the rca outputs of the bel canto using Canare xlr to rca pro audio cable.
The bel canto has a nice low 10 ohm output impedance .

Both subs are set to 50hz and in the positive phase position.

The subs are close to the main speakers so time alignment is not a concern , the subs are placed on the inside of each speaker with the back of the sub around 1.2 metres from the front wall.

Room size is 7.6m x 5m with the speakers placed on the long wall about 3 metres apart.

Putting subs in corners is great for home theatre as they excite the room modes the most there , but it is disastrous for music ime.
Time spent positioning your subs is just as important as time spent positioning your main speakers , it took me several weekends of moving them around to find the best positions , but the payoff is well worth the effort.

.
ATC SM100 ASL PRO , SCM20 ASL PRO MK2 , Two ATC C4 SCM 0.1/12 Subwoofers.
Bel Canto Pre6 Gen2 multi channel preamp , Oppo BDP95 , Wadia WT3200 cd transport , Benchmark dac1 HDR.
Technics SL1000MK3 turntable , Dynavector 17d3 , Whest PS30R.

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