SHL5s balance in my room

[thurston]

(Unfortunately) far too much praise for me.

I found the solution using triangular rockwool in the corners in a German forum adressing to people doing DIY home recording-studios. These things even have a name: they´re called "superchunks".

Just made a short walk with my dog and came to the result (fresh air supports thinking) that they may as well work in lower regions. (maybe to less extent)
The measures I mentioned apply only if the signal hits the absorbers right angled.
If they hit it under 45° then the length for example will be 60cm multiplied with 1,41

I intend to dampen the ceiling (for higher frequencies) using commercially available acoustic elements (probably Vicoustic, cause they look good).

I mentioned it before. Such elements helped a lot dampening the rear wall were I have to sit relatively close.
Also I intend to install equally constructed bass absorbers in the other two corners in order to give the space more headroom regarding the bass-absorption-potential.

[Pluto]

...That's an -11dB dip at 50Hz! It really is crazy how much boom I'm getting.

With a -3dB dip at 31.5Hz and 40Hz I'm getting quite an 'even' sound. The trade off being that they've lost some scale. Am I ever going to beat this?

I wonder if your chimney is at the root of this. You are sitting at the bottom of a nice, big, tuned organ pipe.

Does anyone have any experience with this unit? http://www.behringer.com/EN/Products/DEQ2496.aspx

This Behringer unit is widely used and does exactly what it says on the tin - it's probably quite a good toolbox for addressing your problem which is now quite clearly defined. The interface is a bit fiddly as it involves an awful lot of information on a tiny screen.

A function of particular interest in your case is the "dynamic EQ" (page 9 of the manual) which, if I understand its operation correctly, can apply variable amounts of frequency correction with increasing level. Acoustical anomalies such as yours are frequently level dependent - you may find that at "dead of night" listening levels there is simply no problem but the resonance is excited disproportionately with increasing level.

Some use of a measurement microphone might help to keep matters in proportion. You have previously mentioned that you are in London? Where about? I might be able to render some assistance and I have a decent calibrated mic. that might be useful after the main issue is cracked.

Incidentally, the fact that you found the primary resonance does not mean that the ideal filter is one that operates at that frequency alone. All resonant systems have a Q factor ("quality"). Low Q implies a relatively small resonance spread over a wide frequency range. Your issue appears to be quite high Q, a rather vicious but relatively narrow range. The ideal corrective filter needs to take into consideration the fact that all filters cause collateral damage to the signal - the trick is not to throw the baby out with the bathwater.

[jack667]

I wonder if your chimney is at the root of this. You are sitting at the bottom of a nice, big, tuned organ pipe.

This Behringer unit is widely used and does exactly what it says on the tin - it's probably quite a good toolbox for addressing your problem which is now quite clearly defined. The interface is a bit fiddly as it involves an awful lot of information on a tiny screen.

A function of particular interest in your case is the "dynamic EQ" (page 9 of the manual) which, if I understand its operation correctly, can apply variable amounts of frequency correction with increasing level. Acoustical anomalies such as yours are frequently level dependent - you may find that at "dead of night" listening levels there is simply no problem but the resonance is excited disproportionately with increasing level.

Some use of a measurement microphone might help to keep matters in proportion. You have previously mentioned that you are in London? Where about? I might be able to render some assistance and I have a decent calibrated mic. that might be useful after the main issue is cracked.

Incidentally, the fact that you found the primary resonance does not mean that the ideal filter is one that operates at that frequency alone. All resonant systems have a Q factor ("quality"). Low Q implies a relatively small resonance spread over a wide frequency range. Your issue appears to be quite high Q, a rather vicious but relatively narrow range. The ideal corrective filter needs to take into consideration the fact that all filters cause collateral damage to the signal - the trick is not to throw the baby out with the bathwater.

Solid advice there Pluto. One thing I'd say about the chimney is it's actually been blocked - being a 6 story Victorian house built in 1860 that's been converted into flats, all of the chimneys were blocked, it's just the fireplaces that are still intact.

I'm based in Bayswater, central London (W2 postcode, 5 minutes away from Paddington)

Thanks for your help with the EQ. I've got one on order now so I'll give it a go and post my results when it arrives. Very excited to get my problem sorted!

[Pluto]

One thing I'd say about the chimney is it's actually been blocked - being a 6 story Victorian house built in 1860 that's been converted into flats, all of the chimneys were blocked, it's just the fireplaces that are still intact.

Any idea how? Six stories is one hell of a pipe so unless the whole structure really has been solidly bricked-up, I wouldn't be at all surprised if significant resonant pockets remained. Do you ever hear noises from the fireplace or any low-frequency "groaning" without obvious explanation?

[A.S.]

Any idea how? Six stories is one hell of a pipe so unless the whole structure really has been solidly bricked-up, ....

I was going to make the same point.

Sound is strange, invisible and frequently difficult to imagine. In the Victorian era, the only way of heating a house was with individual fireplaces in every room on every floor, connected to the roof by a labyrinth of chimney tunnels up which smoke was conveyed to the roof chimney stack and away. We know from organ pipes that the end furthest from the mouth can be open or closed: the pipe will still sound at a characteristic note even if the far end is open (surprisingly perhaps) and at a different note if the same pipe is closed. So, just because the chimney has been apparently blocked-off still raises many acoustic questions. Is the fireplace (the mouth of the pipe) still open? Can you see up inside at all? Even if it is blocked at both ends, it is still (theoretically) an undamped pipe, and in the circumstances where the compliance of whatever is blocking the end or ends (even bricks) is in resonance with a small external force (perhaps the speakers, a neighbours pipe, even wind blowing across the room end) the result will be that the pipe honks.

I covered this effect here, and of damping the resonance. I'd be curious to know what happens to then big peak if you stuff Rockwool into the fireplace end to increase the damping.

I should also remind you of my experience at the previous Harbeth R&D place. The listening room led off to a large kitchen area with modern built-in vinyl-skinned chipboard cupboards. With these cupboard doors gently closed, a firm thump on the door with a hand produced a dramatic low frequency boom - about 40Hz - the cupboard doors although they looked solid were in fact compliant springs held loosely over the air-volume of the cupboards. At a frequency at which the door and the cupboard air has some mechanical synergy, the result was a terrible bass hang-over. All critical listening had to be with the doors wide open. A chimney is exactly the same issue.

Previous videos here: around my home with a room-door bang test

A beer bottle resonator - damping of cavity/pipe resonance

[jack667]

I was going to make the same point.

Sound is strange, invisible and frequenctly difficult to imagine. In the Victorian era, the only way of heating a house was with individual fireplaces in every room on every floor, connected to the roof by a labyrinth of chimney tunnels up which smoke was conveyed to the roof chimney stack and .....]

That's a really interesting recording there Alan.. amazing to think the resonance given off by normal items around the home.

Regarding the chimney, it's an iron faced fireplace, that has been blocked as far as I can see (no openings at all). If I 'thump' on the walls surrounding, it sounds very dead and flat, suggesting that is probably was bricked up. One thing I could try is swapping the entire room back to front.. although I'm not sure that would have any effect, but you never know. Perhaps uneven floor supports or something that could be contributing as well. I guess the only thing is, if it is giving off any resonance, I'd imagine it'll be exactly the same, if not worse if I swapped the room around (with it behind the sofa). One other thing to mention, the fireplace is set back slightly where the ironface is (maybe 20cm or so into the wall), as it's hidden behind the tv unit currently, I could actually fit a roll or two of rockwool in there just to see if it makes any difference.

In response to your 'bang test' - I noticed my sofa has a good low thump actually - it's just a cheap sofa that probably isn't stuffed very well - hollow wooden frame with not much else I'd imagine. Would it benefit at all if I stuffed it with something like rockwool? (not sure how safe this is if it's a dangerous substance or not? Especially living with someone who suffers from asthma)

What pains me is the room I was in before was actually a small attic - around 3x3m, also in a Victorian house - I had a dedicated room, and the ceiling (triangular shaped) peaked at about 6ft 2 - I couldn't actually stand up straight in the room! The sound in there? Absolutely perfect. Everything sounded right, even back when I had the huge unsightly Spendor S9e's in there (which are known for having hard-to-manage bass amongst other things).

[A.S.]

... What pains me is the room I was in before was actually a small attic - around 3x3m, also in a Victorian house - I had a dedicated room, and the ceiling (triangular shaped) peaked at about 6ft 2 - I couldn't actually stand up straight in the room! The sound in there? Absolutely perfect. Everything sounded right, even back when I had the huge unsightly Spendor S9e's in there (which are known for having hard-to-manage bass amongst other things).

First, I really wouldn't start stuffing the furniture with Rockwool. To be effective you really need acoustic mass and that implies more than a few handfuls of Rockwool rammed into spaces in the furniture. It means really loading it with as much as possible.

I think we can explain why everything sounded so nice in your small room. It was probably a combination of several effects which combined for acoustic bliss ...

1) The small dimensions meant that low frequencies (long wavelengths) just couldn't build-up in the room (the room acted as a sort of bass-cut control) and ...
2) my recollection of attic/loft space is of many supporting and partitioning joists (wooden beams) and those divide-up long walls into smaller much more rigid areas and ...
3) those smaller areas are extremely stiff ... which means that they are resistant to being excited into motion by the low frequencies and as there aren't any low frequencies (see 1) to excite them...
4) the overall damping in the middle frequencies is just about perfect.

Perhaps the walls/ceiling were not parallel? You might also want to stuff the speaker ports with socks to reduce the vent outputs, just as an experiment.

Incidentally, when you made your very impressive sweep test, did you drive one speaker at a time and (mentally) take an average response or did you drive both together? You should only drive one at a time.

[jack667]

First, I really wouldn't start stuffing the furniture with Rockwool. To be effective you really need acoustic mass and that implies more than a few handfuls of Rockwool rammed into spaces in the furniture. It means really loading it with as much as possible.

I think we can explain why everything sounded so nice in your small room. It was probably a combination of several effects which combined for acoustic bliss ...

1) The small dimensions meant that low frequencies (long wavelengths) just couldn't build-up in the room (the room acted as a sort of bass-cut control) and ...
2) my recollection of attic/loft space is of many supporting and partitioning joists (wooden beams) and those divide-up long walls into smaller much more rigid areas and ...
3) those smaller areas are extremely stiff ... which means that they are resistant to being excited into motion by the low frequencies and as there aren't any low frequencies (see 1) to excite them...
4) the overall damping in the middle frequencies is just about perfect.

Perhaps the walls/ceiling were not parallel? You might also want to stuff the speaker ports with socks to reduce the vent outputs, just as an experiment.

Incidentally, when you made your very impressive sweep test, did you drive one speaker at a time and (mentally) take an average response or did you drive both together? You should only drive one at a time.

Thanks for the insight Alan.

When I carried out the frequency test, I drove one speaker at a time, both with peaks around 52Hz.

I have the EQ on order now and you can EQ per channel I believe.

Give me a few days and I'll post my results.

I did think about stuffing the ports but because these are the demo SHL5's directly from you guys (via Arif at KJ West One) and I didn't want to damage them trying to get the grilles off.

Whatever happens Harbeth is the sound I've been looking (listening?- ha) for, for the last 10 years. The only other speaker I've enjoyed as much is the TAD reference ones in the mastering suite at Air London, purely because it's an exhilarating experience hearing your own music back in a studio like that.

Thanks guys

[A.S.]

I found my eq box in the stores. What I used is the now obsolete Berhringer Ultra-Curve Pro DSP8024, introduced over ten years ago. If you can find one second-hand and it works correctly, it's a fantastic piece of kit when used properly and sensitively.

And for the naysayers who will no doubt complain that the introduction of this system into the audio chain will chronically disturb fidelity (it won't), the unit has ....

... Relay-controlled hard bypass with an auto-bypass function during power failure (failsafe relay)

so that it can be completely bypassed as if it were not in circuit at all.

[jack667]

I found my eq box in the stores. What I used is the now obsolete Berhringer Ultra-Curve Pro DSP8024, introduced over ten years ago. If you can find one second-hand and it works correctly, it's a fantastic piece of kit when used properly and sensitively.

And for the naysayers who will no doubt complain that the introduction of this system into the audio chain will chronically disturb fidelity (it won't), the unit has ....

so that it can be completely bypassed as if it were not in circuit at all.

Couldn't agree more. Let me say from a professional level, there is absolutely none of this snake-oil 'audiophile' nonsense about 'destroying the audio chain' when it comes to working in the studio. Bearing in mind, something I might record may have ran through several (hardware) audio processors - compressors, limiters, EQs - you name it!

Even after I'm done composing and we go to mastering, the signal is processed further still when we add any additional EQing and compression - be it digital or even valve.

See here:


I was really pleased to see your post a little while back about tone controls on amplifiers too, it follows the same theory.

[STHLS5]

@ST:

Exactly as you write!

I think your the absorption will improve if you replace the shrink wrappers with a fabric. Plastic will block the waves from reaching the rockwool. There is a complete guide written by Alan somewhere here (can't find the link). I used wire mesh to hold the rockwool in place and then covered them with fabric.

ST

{Moderator's comment: only theoretically. At low/mid frequencies sound will penetrate walls with ease, and just laugh at a 0.1mm thickness of plastic or cloth. At HF yes, some difference.}

[A.S.]

In BBC speakers LS5/8 and LS5/9 the walls are internally lined with Rockwool., not foam. To prevent the Rockwool blowing out through the port, it is covered with polythene sheeting, which is stapled down to seal the Rockwool.

[A.S.]

Do audiophiles occasionally or ever put a foot in the studio or the concert hall? Not often in my experience. Consequently, deprived of contact with the real world they develop a fantasy about what goes on there and what live /studio sound is really like.

You're lucky in that you are in control of the composition through mastering process. Very few artists have (or care about) technology - they leave it to the technocrats to 'do whatever is necessary' to make the resulting sound sell-able. And if that means layer upon layer of effects, processing, tone adjustment, compression and the rest - so what? The recording front end is not primarily about striving for sonic excellence. That is an accidental by-product unless the producer has the budget to pander to 1% of the market who are listening on separates.

It should be mandatory for anyone who aspires to be an audiophile to take the 'real world sonic driving test', which would include time at the front end of the process. They they'd be able to write with authority and influence others from a position of real knowledge.

As a matter of interest, if you asked your studio chums how often they fret about cables, interconnects, power supplies, connectors, DACs and the gamut of audiophile props, what would they say? Perhaps you could ask them.

[jack667]

As a matter of interest, if you asked your studio chums how often they fret about cables, interconnects, power supplies, connectors, DACs and the gamut of audiophile props, what would they say? Perhaps you could ask them.

Honest answer? Not once - ever. The cables we care about are ones that are reasonably priced, durable and stand the test of time. Be that XLR, jack or whatever else. If we can connect things via balanced connections then yes, we always will - and sometimes the things we connect require additional phantom power (usually 12v) that must be connected via XLR. In terms of power, it's more a matter of safety. If I use an outboard with 20 different 19" rack devices all daisy-chained, I just need to make sure it's safe and surge protected.

The same goes with how it's stacked - it's more of an issue of portability - a good outboard rack on wheels with no isolation always does the job - none of it generates very much heat, so you can stack up as much as you like directly on-top of one another.

Whenever I talk to anyone who is involved in the industry, the number one thing that's discussed every time is simple: Room acoustics.

I agree with you completely - people really need their eyes-opening. I don't want to name-names but some of these companies that sell an array of after market products really saddens me, and it's even worse when marketeers have tricked people into believing they really are getting a better (or even different sound!).

I feel that it's just part of the hobby, which in turn really has nothing to do with the music - we know in some cases it's obsessive, people get the 'upgrade bug' etc. I guess this just leads to tweaking and modifying constantly.

The thing that attracted me to Harbeth in the first place was the no-nonsense, honest vision of a company that actually know what they're talking about. It's a shame we can't say the same for many other companies! That's just my view.

[jack667]

Hi all,

So a little update. I bought the EQ and spent hours fiddling with it. After a week or so with it, I've decided it doesn't fix the problem I'm having, just changes it. If I pull down the levels around 40-50-60hz I just lose something from the music that is so special with the SHL5. Also, for some unknown reason my Bladelius amp doesn't have a proper tape loop - so I can't actually run it efficiently, just through one source at a time which is rather frustrating. The problem with those frequencies is they're also responsible for a good amount of the 'punch' in a kick drum, so if I lower them with the EQ.. I lose some of that.

I also now have the Compact 7s on home demo. I have them on the same stands (Atacama SL400s) so they're a little bit low, but I propped them up with some books for now. I don't know why, but I just prefer the sound of the SHL5 even though they're causing me all sorts of headaches in my room. They sound warmer to my ears, sweeter, bigger sound stage, where as the Compact 7s sound more 'boxed in' (just to my ears).

So now I'm in a real dilemma.. I love the scale and authority of the SHL5s, but I'm going to need to work hard to get them sounding balanced in my room. I know there's no other speaker for me, and some of you may find this surprising, but my partner said she actually prefers the look of the bigger SHL5! She was in agreement with me, there's just something magical about that speaker that the Compact7 didn't capture for us (although very close).

I live in rented accommodation in central London with absolutely no plans to leave.. I'm limited with space, time, money - and of course the overall appearance of the room. This also restricts what I can physically do with the room, because it's not mine. I understand that it's all a compromise, so now I think I need to start experimenting with some Rockwool for now.

I just wanted to say thanks again to all who took the time to read this thread and offer some advice - it's been greatly appreciated.

I'm very excited to receive my own SHL5s!

Thanks

[thurston]

...have to "reply" to my own post No.26 where I say that an overdamped room is not likely to happen.

Well, my learning curve going further and further. Have to say that I now did experience exactly that: an over damped room. Music somehow did not really let loose. It was held back.

Therefore my plans were changed: in addition to absorption I will add some diffusers.

[STHLS5]

...have to "reply" to my own post No.26 where I say that an overdamped room is not likely to happen.

Well, my learning curve going further and further. Have to say that I now did experience exactly that: an over damped room. Music somehow did not really let loose. It was held back.

Therefore my plans were changed: in addition to absorption I will add some diffusers.

Been there. Too much damping kills the sparkle but there will be control in your music. Separation between instruments and you can hear micro details. I started the room with too much damping and then added diffusers and reflectors until I get the balance for a good sound. A lot of damping gives you clean bass. A liitle reflectors over the damping keep the HF alive. It will take months to get it right.

ST

[keithwwk]

Same here, been there 17yrs ago when I experiencing simple room treatment.

I tried old twin mattresses to cover corners and 1st reflection point side walls with too much damping in my old room and result was overkill (Once enter to the room the sudden reduce in noise was very obvious).

Music became lifeless, can turn vol real loud but fatigue after some time.

[thurston]

The thing that surprised me that adding absorption made the listening experience better and better.

But adding just a LITTLE too much killed everything. Liked it at first, but listening the whole evening a feeling grew that it missed the fun it used to have.

Live recordings (with real ambience) were better. Studio recording sound a little dull, uninteresting.

Well mostly one listens to studio recordings!