Musing about upgrades - Two sets of speakers (in the same room) ?

[Sloop John B]

The LS50 Wireless II's built-in EQ options include a setting for placement close to the front wall. You cannot jam them up against the wall like an SL2, but you can get close.

Whilst I realise I can “dial in” distance and room data into the KEFs, what distance from the rear wall would you recommend if there are no constraints?

.sjb

 

[Rodrat]

I run TDL reference standards and Devialet silver phantoms in the same room. No problem and each does different things. Love to also run my Maggies but I don't have the space to place them even moving out the others and they need new tweeters.

 

[tuga]

Whilst I realise I can “dial in” distance and room data into the KEFs, what distance from the rear wall would you recommend if there are no constraints?

.sjb

For the flattest mid-bass, you could try very close, say 10-20cm (and EQ the sub-bass peaks) or > 2 metres from the front wall.

 

[Strictly Stereo]

Whilst I realise I can “dial in” distance and room data into the KEFs, what distance from the rear wall would you recommend if there are no constraints?

.sjb

If you are not using the EQ to compensate, then treat them like any other pair of ported stand-mount speakers. What you hear at the listening position is going to be coloured by the resonances and reflections in room, as well as the distance from the speakers to the wall. I would probably start with them about 50-60cm from the wall and move them backwards or forwards until you find the spot that you like best. KEF recommends using a classic equilateral triangle layout and I have found this to work well.

 

[sailor]

@Sloop John B, regarding having undriven speakers standing idle and affecting the sound. There is a contribution to what is heard, there has to be! The idle bass driver will be modulated by the varying sound pressure in room in the same way you can feel vibration in a window pane, coffee table etc. A speaker driver is essentially the same as a microphone which when modulated produces an electrical output which will charge up the caps in the crossover and release that energy out of step with the music.

The good news is: Don't worry about it. For peace of mind as was mentioned you can short out the speaker terminals, the dynamic damping will mitigate any deleterious output. An interesting experiment is to take a loose speaker and wobble the cone in and out by grasping it gently between the fingers on either side of the frame, then short out the terminals and try again, a distinct reluctance to move will be felt. The bigger and more sensitive the driver the bigger the effect which will show on a multi-meter set to AC Volts.

My guess is the acoustics of your average home listening room will have a greater detrimental impact on the sound than a second pair of speakers.

Agreeing with the above I consider this a non-issue.

To address the choice of position 'A' or 'B' well it depends. You having not mentioned any room treatment I will assume you have little to none.

Position A: represents a very asymmetrical layout. The wall on your right hand side is close to your listening position (LP) so direct and indirect sound will reach your ears too close together causing loss of detail and some smearing like a lens out of focus. This wall would need lots of broad-band absorption to avoid the damage of strong early reflections.

Position B: represents a nice symmetrical layout and will be easier to treat acoustically and should provide a very good sound-stage with precise imaging. Having said that, I think too much is made of pin-point imaging, a phenomenon which does not happen in real life.

Position C: for consideration. If we take the line of the black arrows in A as North and South and assuming, once again, that the yellow square is your LP, a set up that can work is to move one speaker to the N wall and the other to the E wall placed equidistant from the truncated NE corner.

I'm in SW Limerick and occasionally travel to Dublin and could, if you wish, bring along my Omnimic measurement system. I ordered a replacement impulse disc months ago but has not arrived so need to order another.

 

[docstocker]

The only ‘musts’ in our hobby are those for electrical safety

I speak as owner of three turntables and 11 pairs of speakers
Swapping things around is all part of the fun
Thank goodness we have got away from ‘the dealer knows best and only he can fit your cartridge, set up your deck etc’

Enjoy your music AND your hi-fi anyway YOU choose
J

 

[Sloop John B]

Position A: represents a very asymmetrical layout. The wall on your right hand side is close to your listening position (LP) so direct and indirect sound will reach your ears too close together causing loss of detail and some smearing like a lens out of focus. This wall would need lots of broad-band absorption to avoid the damage of strong early reflections.

Even worse than you think - it’s a window!

I'm in SW Limerick and occasionally travel to Dublin and could, if you wish, bring along my Omnimic measurement system. I ordered a replacement impulse disc months ago but has not arrived so need to order another.

Very kind offer and certainly if you have the time when you’re up in Dublin to call in I’d certainly appreciate your input.

.sjb

 

[Strictly Stereo]

Position B: represents a nice symmetrical layout and will be easier to treat acoustically and should provide a very good sound-stage with precise imaging. Having said that, I think too much is made of pin-point imaging, a phenomenon which does not happen in real life.

Can I ask what you mean by "does not happen in real life" here? Human beings have evolved the equipment and skills required to locate the source of different sounds.

 

[tuga]

Even worse than you think - it’s a window!

Not as different from plasteboard as one would expect:

 

[SteveH]

I speak as owner of three turntables and 11 pairs of speakers

At least you're not obsessive about your hobby!

 

[gez]

Not as different from plasteboard as one would expect:

Interesting given that glass is usually blamed for introducing a bright ringing, yet it absorbs better at high frequencies than plasterboard does according to that graph, so your room would (theoretically) sound less "bright" if all it's walls were made of glass rather than plasterboard.

 

[Strictly Stereo]

Interesting given that glass is usually blamed for introducing a bright ringing, yet it absorbs better at high frequencies than plasterboard does according to that graph, so your room would (theoretically) sound less "bright" if all it's walls were made of glass rather than plasterboard.

Glass does resonate. So does plasterboard. You are right about the all glass room sounding less bright though, at least based on this chart, but I think that the more even absorption across a wide band offered by the plasterboard would make for a better-sounding room.

 

[tuga]

Glass does resonate. So does plasterboard. You are right about the all glass room sounding less bright though, at least based on this chart, but I think that the more even absorption across a wide band offered by the plasterboard would make for a better-sounding room.

A room with bare walls would sound bad with either.

 

[ToTo Man]

Interesting given that glass is usually blamed for introducing a bright ringing, yet it absorbs better at high frequencies than plasterboard does according to that graph, so your room would (theoretically) sound less "bright" if all it's walls were made of glass rather than plasterboard.

Glass does resonate. So does plasterboard. You are right about the all glass room sounding less bright though, at least based on this chart, but I think that the more even absorption across a wide band offered by the plasterboard would make for a better-sounding room.

Unless I'm reading the graph wrong, it's the plasterboard that has the superior absorption above 2kHz, not the glass. At 4kHz, the plasterboard has an absorption coefficient of approx 0.1 vs approx 0.02 which equates to the plasterboard being approx 5x more absorptive than the glass at high frequencies.

The glass is more absorptive at lower frequencies, but the absorption coefficient is for a single 4mm pane. I'd expect that absorption coefficient to be lower for double- and triple-glazing.

 

[gez]

Unless I'm reading the graph wrong, it's the plasterboard that has the superior absorption above 2kHz, not the glass. At 4kHz, the plasterboard has an absorption coefficient of approx 0.1 vs approx 0.02 which equates to the plasterboard being approx 5x more absorptive than the glass at high frequencies.

No you're not reading it wrong. Less abosorbsion = more reflected sound at those frequencies. So glass will reflect more above 2khz. Though given how low the absorbsion is in both cases* I'd be surprised if the actual difference would be that great in practice.

*At 4khz plasterboard is reflecting 90% and Glass 98%.

 

[Strictly Stereo]

Unless I'm reading the graph wrong, it's the plasterboard that has the superior absorption above 2kHz, not the glass. At 4kHz, the plasterboard has an absorption coefficient of approx 0.1 vs approx 0.02 which equates to the plasterboard being approx 5x more absorptive than the glass at high frequencies.

You are quite right. I wasn't paying proper attention. I still think that the even wide band absorption offered by the plasterboard would make for a better-sounding room.

 

[ryder]

Unless I'm reading the graph wrong, it's the plasterboard that has the superior absorption above 2kHz, not the glass.

From the graph, at above 2k Hz the glass has better absorption than plasterboard. However, in real world I'm not sure about the difference though.

 

[S-Man]

Another pair of speakers in the room is easily audible. If you want to check, do what I did by accident: put a pair of speakers (in my case, JR,149), to one side of your main speakers .i.e both to the left. It took me a while to figure out why the central stereo image had moved left.

I didn’t try shorting the loudspeaker terminals to see if this fixed the problem, I just moved the JR,149s.

 

[sailor]

Can I ask what you mean by "does not happen in real life"

Yes, evolution has provided us with the ability/need to identify direction and even the height of a sound to prepare for fight or flight and this is the reason why it is desirable to produce faithfully the higher order harmonics which contains the spatial clues which become apparent more and more as you manage to lower the noise floor of the whole system, however when many instruments are massed together that preciseness is somewhat blurred. You can with eyes closed identify that the string section is on your left but it will be difficult to locate exactly where the viola player sits in relation to the violin players and the same with the woodwinds. Open eyes reveal precisely where they are.

With a well recorded jazz quartet using a crossed-mic Blumlein Technique finer instrument location is more precise yet, to my ears still not 'pin-point'

Many times I've sat at a concert closing my eyes to just listen trying to accurately place individual instruments and it's not easy.

 

[the caretaker]

I think the secret of hifi happiness is to do your thing. Whatever brings you pleasure, do it, a lot. Two sets of speakers sounds like great fun to me with endless possibilities.

I thought the secret to hifi happiness was cables? Guess I was wrong...all those years of comparing cables! Long years of comparisons..when all I needed was to do my thing!
Thanks Daz...