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Proximity to LS3/5A

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dalryc

pfm Member
I own a pair of Stirling LS3/5a's on Solid Steel SS7s that I use as rears that sit about 2m from my ears - they sound fine for that function. They are augmenting a pair of Quad ESL 2912s.

I know their origins as outside broadcast near field monitors. I've seen posts of LS3/5a's in reasonable sized rooms used as regular stereo speakers but don't look that close to the listening position. I've tried various configurations but never got on with the sound I'm hearing.

Is there a recommended or user experienced distance that the LS3/5a types will sound best from the listener?
 
There is a trick that can be deployed in typical UK sized living rooms that involves placing them and the listening seat on the ‘wide’ walls, pulling them quite far out into the room and away from the corners and deliberately placing them on the typical 40Hz-ish room node. It works as the LS3/5A has very tight and controlled infinite baffle bass, a bit of a ‘hump’ at 100-110Hz (so don’t sound thin away from walls) and very little energy at 40Hz. Get it right and they can sound surprised big and powerful, though obviously volume and dynamic ability is only what a 1970s 5” bass-mid is capable. We are using physics to our advantage rather than bending its rules here!

PS If you hunt through LS3/5A posts from me I have several times linked to the blog that alerted me to this one. Whilst I can’t keep my LS3/5As in this kind of setup permanently for practical reasons (they are in my ‘record shop’ room and I’d inevitably knock them over moving stock around) I have played about enough to be convinced there is something to this thinking. The node that makes so many modern aggressively ported speakers a honking booming mess in so many rooms plays to the LS3/5A’s advantage remarkably well. It just very gently amplifies the very bottom of their range.
 
I listen to mine in my office system in extreme near field with only about 15cm behind them to the rear wall and they sound fantastic. I don't have the space in here to put them anywhere else.
 
sideshowbob said:
I listen to mine in my office system in extreme near field with only about 15cm behind them to the rear wall and they sound fantastic. I don't have the space in here to put them anywhere else.
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This is how I use mine in my office system too. They sound great. I guess it's pretty much how they would have been used in OB vans and what they were designed for.
 
My preferred set up ( with my hearing) is sitting about 1.5m from the speakers with them pulled way out into the room- bit impractical but really enjoyable. I’ve added a BK xxl400 between and slightly behind their plane and it works a treat. Their power handling limitation tends to dictate terms in a big room.
 
Tony L said:
There is a trick that can be deployed in typical UK sized living rooms that involves placing them and the listening seat on the ‘wide’ walls, pulling them quite far out into the room and away from the corners and deliberately placing them on the typical 40Hz-ish room node. It works as the LS3/5A has very tight and controlled infinite baffle bass, a bit of a ‘hump’ at 100-110Hz (so don’t sound thin away from walls) and very little energy at 40Hz. Get it right and they can sound surprised big and powerful, though obviously volume and dynamic ability is only what a 1970s 5” bass-mid is capable. We are using physics to our advantage rather than bending its rules here!

PS If you hunt through LS3/5A posts from me I have several times linked to the blog that alerted me to this one. Whilst I can’t keep my LS3/5As in this kind of setup permanently for practical reasons (they are in my ‘record shop’ room and I’d inevitably knock them over moving stock around) I have played about enough to be convinced there is something to this thinking. The node that makes so many modern aggressively ported speakers a honking booming mess in so many rooms plays to the LS3/5A’s advantage remarkably well. It just very gently amplifies the very bottom of their range.
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Tony, how do you go about finding that handy room mode spot? I’d like to try that.
 
TheDecameron said:
Tony, how do you go about finding that handy room mode spot? I’d like to try that.
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Trial and error to some degree, though in a typical rectangular UK living room with the speakers well out of the corners and firing across the short dimension of the room it’s about 1 to 1.5 metres or so from the front wall. Here’s the blog I picked this up from (Medialux).
 
TheDecameron said:
My preferred set up ( with my hearing) is sitting about 1.5m from the speakers with them pulled way out into the room- bit impractical but really enjoyable. I’ve added a BK xxl400 between and slightly behind their plane and it works a treat. Their power handling limitation tends to dictate terms in a big room.
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I'm happy to experiment and have the time.
I'm very curious to find out why they are rated so highly (Ken Kessler etc).
I'm also waiting on a pair of BK XXL400 as I find subs to be directional.
 
From the above link:

"In every rectangular room with the speaker positioned at the long wall we will have an energy maxima (room mode) at 40hz around 1 – 1,5m in front of the long walls."

Really?! I'd like to see some evidence of that. :)

Modal behaviour depends on room dimensions. For a room to have a 40Hz mode, it needs to be either 4.3m long (or a multiple, i.e. 8.6m, 12.9m, etc), 8.6m wide, or else it needs to have a ceiling height of 4.3m.

I tried this advice with the Falcon Q7 in my 4.1m x 3.8m x 3.2m room and ended up with a peak at 120Hz, not 40Hz. IME the best way to excite 40Hz in this size of room is either to place the speakers close to the front wall or sit close to the rear wall. The closer both are to the boundaries the stronger 40Hz becomes. Conversely, the further both are moved out from the boundaries the weaker 40Hz becomes. You can tune to taste but what you want to avoid of course is placing your speakers or listening seat on the room's centre line as this will completely null out 40Hz!
 
ToTo Man said:
From the above link:

"In every rectangular room with the speaker positioned at the long wall we will have an energy maxima (room mode) at 40hz around 1 – 1,5m in front of the long walls."

Really?! I'd like to see some evidence of that. :)

Modal behaviour depends on room dimensions. For a room to have a 40Hz mode, it needs to be either 4.3m long (or a multiple, i.e. 8.6m, 12.9m, etc), 8.6m wide, or else it needs to have a ceiling height of 4.3m.

I tried this advice with the Falcon Q7 in my 4.1m x 3.8m x 3.2m room and ended up with a peak at 120Hz, not 40Hz. IME the best way to excite 40Hz in this size of room is either to place the speakers close to the front wall or sit close to the rear wall. The closer both are to the boundaries the stronger 40Hz becomes. Conversely, the further both are moved out from the boundaries the weaker 40Hz becomes. You can tune to taste but what you want to avoid of course is placing your speakers or listening seat on the room's centre line as this will completely null out 40Hz!
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Maybe that's where I have an issue. My room is 4.5m x 4.5m with a vaulted ceiling - it's room mode is about 75Hz.
 
ToTo Man said:
Modal behaviour depends on room dimensions. For a room to have a 40Hz mode, it needs to be either 4.3m long (or a multiple, i.e. 8.6m, 12.9m, etc), 8.6m wide, or else it needs to have a ceiling height of 4.3m.
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Yes, to my mind it is a typically small UK room thing. I live in a 3 bed Victorian terrace (the larger type with two living rooms and the kitchen/bathroom under an additional gable), my room size is not far off the four bed 1930s semi I grew up in.

7892690332_a44b2211eb_c.jpg


Here’s my front room dimensions. It’s not to scale, but the measurements are accurate. When I had the MEG RL-904s I had a horrendous 41.5Hz room boom (the Tannoys and Harbeths never hit it, it was a port frequency thing). I briefly tried the LS3/5As stood in front of my Tannoys and they sounded wonderful, not as dynamic, but barely any smaller. I think I was on the node as they were about where the MEGs boomed so badly. Sure, it is an inconclusive dem as the un-driven Tannoys may have been contributing something, but I wasn’t going to lump them out of the room to test that. My listening seat is close to the back wall so I certainly get some bass reinforcement there.

I also experimented upstairs and found similar good spots, again balancing speaker and seat position and there were positions they really jump in size and weight.

The math will obviously be variable based on specific room dimensions, but I am pretty certain the article is right in theory. The practical result may vary from say a lift at 30Hz to 60Hz, as will the impact of the LS3/5A’s bass bump at 100-110Hz or so. This is a huge factor and why this positioning works with the LS3/5A but doesn’t with say the JR149 that starts to sound lean and sucked-out in the upper bass too far from a wall. Certainly something to it and I’d advise folk with LS3/5As to have a play.
 
dalryc said:
Maybe that's where I have an issue. My room is 4.5m x 4.5m with a vaulted ceiling - it's room mode is about 75Hz.
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Yes, I just checked the REW Room Simulator and with your room dimensions, as you move away from the front and back walls, the 38Hz mode gets weaker and the 76Hz mode gets stronger, which will be compounded by the fact that the 3/5A has more output at 76Hz than 38Hz to start with. With a full-range speaker your mode at 38Hz should be stronger than your mode at 76Hz as it's the fundamental axial mode, but the 3/5A's roll-off below 70Hz will probably mean it's energising the 76Hz mode more. If you download REW you can play about with the Room Simulator to help find positions where the 38Hz and 76Hz modes are more balanced. (Hint: 76Hz will be loudest when either the speakers or the listening seat is placed on the room's centre line).
 
ToTo Man said:
Yes, I just checked the REW Room Simulator and with your room dimensions, as you move away from the front and back walls, the 38Hz mode gets weaker and the 76Hz mode gets stronger, which will be compounded by the fact that the 3/5A has more output at 76Hz than 38Hz to start with. With a full-range speaker your mode at 38Hz should be stronger than your mode at 76Hz as it's the fundamental axial mode, but the 3/5A's roll-off below 70Hz will probably mean it's energising the 76Hz mode more. If you download REW you can play about with the Room Simulator to help find positions where the 38Hz and 76Hz modes are more balanced. (Hint: 76Hz will be loudest when either the speakers or the listening seat is placed on the room's centre line).
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You are correct!
I have a DSPeaker AntiMode and the LS3/5a's aren't bothered by the 38Hz mode but are excited about 75Hz.
This is similar to my Quad ESLs - also not known for bass.
I also have Linn Sara's which, being Isobarik, go low and are more excited by the 38Hz mode than the 75Hz mode.

Time to delve into the REW Simulator - thanks.
 
dalryc said:
Take a look at REW Room Simulator to find that out.
You can play about with speaker positioning and see how it impacts the response.
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I don’t have the gear to do that but would an spl meter and a test tone generator be enough to track down the spot? I could just about manage that.
 
TheDecameron said:
I don’t have the gear to do that but would an spl meter and a test tone generator be enough to track down the spot? I could just about manage that.
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It's a simulator so no gear is required.

I've modified the room dimensions, seating position,speaker position, -3dB speaker frequency and the simulator predicts what the frequency response is.
The prediction is similar to the measured response I get from my DSPeaker anti-mode.

It's free so worth a shot.
 
TheDecameron said:
I don’t have the gear to do that but would an spl meter and a test tone generator be enough to track down the spot? I could just about manage that.
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No equipment required other than a computer on which to install REW:
https://www.roomeqwizard.com/

After installing and launching it, click the 'Room Simulator' icon, input your room dimensions and speaker's low frequency extension capability, and then see what happens to the in-room low frequency response as you move your speakers and/or listening seat around in all three axes.

If your room is a standard shape with no significant idiosyncrasies then you should find the model pretty accurate to what you hear, but there will almost always be one or more quirks specific to your room that the simulator won't reveal.

REW-Room-Sim.jpg
 
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