The Listening Room Reality

Stereophile is one of the most serious audio magazine. I don’t think they write moron things.
Audio is more complex than scientific specs Thomas. But you certainly know that.
I read you on the french forum and you admitted having very very little experience with different speakers. So some humility would not be too much I feel.

No worries…it’s just a try…

BTW…my speakers are 6 years old so I guess I am sticking to the thread title :grinning:

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Oh yes, it is… :pensive:

It took some absorption and diffusion on the left side, and a huge full range absorber on the right side to fix the problem.

The veil used as room separator (on the right sider) is highly efficient down to 500Hz. A slight toe in also made a significant difference.

Of course, all that doesn’t restore symmetry

But it’s not so bad. As far as the big system sounds better than my HD600 headphones it’s ok :sweat_smile:

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Just listened to these two songs:

I usually don’t listen to Rock music, and never really appreciated how it sounds through speakers. Bass is usually too present, masking the rest and making it unpleasant and fatiguing to listen to. Even with the smaller speakers I had before.

When I listen to some Pink Floy or Dire Straits, which is really occasional, I prefer it through headphones, which have a more flat frequency responds.

The Monster Bass Traps behind the speakers proved again being nearly magical.

I think I’ll place an order for two large Monsters :partying_face:

Thomas, could you try and do an experiment with this before ordering ( I know Im not your Father🤪):
Could you try and lay the 2 upright panels on their sides behind the speakers and compare, as in my case in my room a full absorption panel 120 high right behind both speekers for some illogical reason killed the sound further up a bit. For this I ended with only 2 half panel 60x60 behind my speakers concealed by my semi drawn curtains+ the big monster trap on the floor please? ( Wouldn’t it be so much easier, if we lived round the corner from each other :partying_face:) ATB Peter

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Some rooms , with acoustic treatment, from well known audio specialists. For curiosity.

Joël Chevassus / audiophile magazine. France

Srayan Eben 6 moons audio

Roy Gregory audio beat

Mike Malinowski / absolute sound

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Good Evening All,

Just playing the first track off London Grammars ‘If you wait’, where was that bass hiding before???

I can only repeat people who haven’t seriously investigated room acoustic treatment really need to give it a try…




Well well, I couldn’t agree more! As good old KenC would say, Enjoy/Peter

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Hi FR. I’d put money on either the first or the last. :nerd_face: ATB Peter

The first system is: Vivid audio speakers / Coinciident statement line stage ( tubes)/ Luxman monos ( hybrids) / Audiomat reference streamer / Dac.
Around 60 k system.

The second : Walker audio proscenium turntable/ tenor audio electronics / Wilson audio Alexandria
Around 400 k system.

So I would take this last, sold it, buy a home in the south of France ( 50 m2) and buy an S1, 500 dr, and Nd555 and speakers.

Here the system 2, in the personal house of Mike. Mike describes his system and acoustic treatment.

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I was asked about my room treatment, well…

Without acoustic treatment the room has a +22db peak at 42.5Hz.

Bass traps I have 8sqm of absorption with a primary absorption band of 40Hz to about 250Hz, then tailing off to comparatively little absorption above 500Hz. These consist of rockwool encased in a polyethylene membrane, thus acting as pressure mode absorbers. These are positioned in the corners and at boundaries of the room. This is the main acoustic room treatment as such, but it’s not the whole story.

I have a suspended wood floor (pine boards on softwood joists) with glass insulation. To reduce the excitation of this by the speakers I use a 35kg plinth below each of the three speakers. Each of these consists of four of the high density ‘bricks’ from inside a night storage heater sandwiched between two 450mm x 450mm floor tiles, the whole lot being glued together with a modified silane adhesive. This adhesive layer provides sub-critical damping that prevents the whole system from ringing.

In conjunction with bass traps and the bass roll off of the main speakers these measures reduce the 42.5Hz bass peak to +3dB wrt 1kHz.

The plinth under the sub also floats on four sorbothane blocks placed close together near the middle of the plinth, and resting on another 450mm x 450mm floor tile. This provides for a degree of surge to be allowed in reaction the cone of the sub (this is then mainly controlled by the 35kg mass of the suspended plinth) whilst allowing a smaller amount of this to be translated into pitch. This simultaneously limits the transfer of this energy to the floor and gives a reduced damping of the pitch motion. This also allows a small degree of movement in roll yaw and sway, whilst largely constraining and damping heave.

In addition to this the signal feed to the sub has a strong notch filter at the 42.5Hz resonance point of the room and is place mid wall to reduce coupling to the 42.5Hz fundamental resonance of the room, acting together, these measures prevent significant further excitation of the resonance.

The speakers I use have the ScanSpeak D2008 tweeter which is quite directional, and best used ‘on axis’ or near to axis. To reduce lateral reflections from side walls, the speakers are ‘toed-in’ to cross about 5° in front of the listening position. 1st reflection diffusers aren’t particularly needed with this arrangement, but I do intend to try arranging some in the future (along with rear wall diffuers).

The net result is a response ±7dB 15Hz - 18kHz measured 1/12 octave and ±4dB measured 1/3 octave with an RT60 variation of <2:1 across the audio spectrum.


Xanthe, only because I am curious. Do your Spendor SP2, monitor speakers, really need a nap 300 dr?
They seem relatively easy to drive and these are bookshelves speakers.
A nap 250 dr would not be more than enough?

Do they need a NAP300DR… well, no.
Do they benefit from a NAP300DR… oh yes!

(I should point out that my SP2s have modified crossovers and wiring that, together, greatly increase their capacity to resolve fine detail in the sound. Even replacing the caphead screws with button head screws made an audible, and beneficial difference.)


I had doubts myself before I heard the Fact 12s, but For such small speakers they were quite amazing. Certainly full range. Not the power capability of the MB2, but then they are much smaller and only 2/3rds the price. My reaction on hearing them was that if I ever had the misfortune to have to downsize to a small room and found my speakers too big, the Fact 12s may be the right solution keeping the low end if the music that is such an important component for helping convey the emotion in some music. But indeed in a small room in particular treatment may be essential.

You mention Stereophile: but I don’t recall seeing them reviewed by Stereophile? (If I’ve missed it please point me to it.) I do feel that of all the current review publications Stereophile is possibly the best, combining objective tests with the subjective, and seemingly from a fairly neutral point of view, or otherwise clarified by the reviewer. But their first impressions aren’t in the same league, in my experience not giving anything wirthwhile to go by.

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Interesting but puzzling. If you look at the absorbtion characteristics of bass traps they tend to very poor att damping low bass, the absorbtion coefficient his higher for higher frequencies. Your figures also indicate that absorbtion is quite low at 40Hz, and probably highest at 100-200 Hz. This would suggest that you are damping the 100-200 Hz response more than your room mode of 42,5 Hz thus making it more, not less, prominent. Your measurements and experience indicate the opposite. What am I missing (missunderstanding)?


Oh yes they do!
I couldn’t agree more!

And one could state the same for the NAP500DR.

Both 300DR and 500DR have a specific dual-monos design, which makes a significant difference. And, more importantly, is the signal/noise ratio.

The 500DR is astonishingly “silent”.

When I swapped the 300DR with the 500DR the first track I played was piano.
The difference was immediate. (at that time I had “smaller” speakers).

I’m not the kind of person hearing a difference between Ethernet cables (even if I use a fancy AQ), some do, which is fine, I don’t.

But when I swapped the amps… yes, I heard a clear and immediate difference. And so did my wife :wink:

Later I had the same feeling with trios, quartets and bigger ensembles.

But I still remember that first track… it was really moving :relaxed:

Another source of useful information I forgot to mention.
A nice start to room acoustics understanding.

(But, of course, I doesn’t provide the details needed to understand how things actually work)


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Yes you are missing something! :smile:

The majority of commercially available bass traps are essentially large blocks of “acoustic” foam, and indeed they perform badly at low frequencies as they are flow mode absorbers. These give the type of response that you quoted.

My bass traps are damped membrane type absorbers and they have a response consisting of a lower cutoff frequency followed by a broad ‘shelf’ of absorption, then a 6dB to 12dB per octave fall off above this, reaching a limiting absorption value at mid to high frequencies (typically about 18dB less effective than the they are LF).


Interestingly the last (and most effective) power amp I designed was also a dual mono design with a remote power supply!
(Although it still wasn’t as good as a NAP300, it was a lot cheaper to make!)

Stumbled over these Facts second hand sale on FleeBay, and obviously even on Townsend Podiums the owner couldn’t get them work to their satisfaction- now one can’t help wondering why??
Thank you Xanthe for your run down of system/ treatment.
Thomas, did you get a chance to move your absorbers round in different locations in relation to your front wall? ATB Peter