New Home = where to locate the speakers?

[Coach_Kaarlo]

Move them as close as possible to the wall and angle them in. Maybe even more than 30°. Absorb ceiling reflections.

Bass response can be measured nearfield (mic very close to center of woofer). Speaker itself with mic at 1 m, absorn floor bounce and gate signal to eliminate reflections (5 ms would be good). Try setting a gate in REW and see what it does.

Thank you for your suggestions and assistance! I appreciate it.

View attachment 83333
https://amcoustics.com/tools/amray
As i dont't have the correct room measurments i had to guess. Zoom in to get a better poly for circle.

Great tool / sketch. I will try a scale one but yours is pretty accurate. It's counter intuitive to my limited understanding - I would have thought the reflections would lose energy because the space boundaries are divergent. Clearly not so in the measurements or experience.

 

[Trouble Maker]

View attachment 83333
https://amcoustics.com/tools/amray
As i dont't have the correct room measurments i had to guess. Zoom in to get a better poly for circle.

If we all stand around that and start chanting, we might be able to summon Alan Blumlein.

 

[ezra_s]

I have moved everything but the position of speakers was as below;
View attachment 83312
TV was in between speakers but set back closer to the window surface.
View attachment 83314

The blue dot in the centre of the floor is the LP, which is about 1900mm or so direct to each driver.

View attachment 83313
So what do you think? If I move any further out the LP is right up against the rear wall which is on an angle.

I actually want to measure outside to get a baseline for the speaker without reflections, because listening to them out there was subjectively so much better! Any tips for measuring outside?

Another idea I had was to drop them down off the trolleys to change the height mode.

Too close, too much glass?

 

[Coach_Kaarlo]

Measured my outside listening position the other day.

[EDIT: I measured two ways - drivers only with close mic, and both channels at the LP]

Driver measurements below;
https://drive.google.com/file/d/1wf4fEihJg8x_P_VKPTGWfs4tJSrQ7H--/view?usp=sharing

LP measurements below;
https://drive.google.com/file/d/1ZIZgLlW4GwYHPY48IPgXB75VCFfhPVhs/view?usp=sharing

Understand why it sounds so good - because it measures well.

[EDIT: updated the graphs also]

IT was also interesting to play around with the sorbothane hemispheres under the speaker cabinets. Seemed to measure differently, and certainly to touch playing same tone results in much less cabinet vibration, but at some point the bass driver inertia must lack resistance due to the sorbothane softness. Wonder how to test this accurately.


Only thing I was unable to work out was when measuring the woofers was how to gate the measurement correctly - working out the floor bounce and gating accordingly removes all the response under the wavelength / or time delay of the gated measurement. What have I missed?

[EDIT: thanks @MarsianC# for the tip - will live with limited (non-Klippel NFS) measurement capability]


Also is there a way in REW to combine the sweeps of each driver to generate one full range frequency response?

Thanks.

 

[MarsianC#]

Please clarify WHAT has been measured WHERE.

What have I missed?

Check what gating does. With the usual hard reflection around 3 to 5 ms it is impossible to measure bass without room interference. Klippel NFS can do it with "some" math

 

[Coach_Kaarlo]

So even though the driver heights and mic heights differed - the gate is 2.5ms for both.

Which means the woofer looks funny compared to mid and high freq drivers.

What I find interesting is how they measure compared to the factory brochure circa 1980 something.

Brochure.

Measured.

 

[Harmonie]

@Coach_Kaarlo
I didn't read all the measured specs, but discover "real pictures" of your interior since last month's post.
Compared to the sketch, the speakers are "bulkier" and I wonder how big your couch would be in reality.
Did you share the measurements of your room ?
It seems that you will end up with near field listening ?

That + glass surroundings ... maybe your initial "BLUE" option first preference may be the better one ?

 

[richard12511]

I like red, but I would get some acoustic curtains that you can roll open or closed depending on whether your want the view or better sound. Wouldn't want to ruin that view with something that always covers those windows, so best to install window options that allow you to cover them on demand.

 

[Coach_Kaarlo]

@Coach_Kaarlo
I didn't read all the measured specs, but discover "real pictures" of your interior since last month's post.
Compared to the sketch, the speakers are "bulkier" and I wonder how big your couch would be in reality.
Did you share the measurements of your room ?
It seems that you will end up with near field listening ?

That + glass surroundings ... maybe your initial "BLUE" option first preference may be the better one ?

Inside room measurements are here;

https://drive.google.com/file/d/1RsF9Fjky-gz-HI_Esa6oFE00YC2bXqpH/view?usp=sharing

I have a large memory foam 'bean bag' instead of a couch as it is far more absorbent / dampening acoustically (2m^3 of memory foam). But I agree the speakers are very tight and the off axis reflection from the wall behind spoiled the image/ sound unless listening almost nearfield. Outside where they can breathe they sound and measure much better - not surprising really.

 

[Coach_Kaarlo]

I like red, but I would get some acoustic curtains that you can roll open or closed depending on whether your want the view or better sound. Wouldn't want to ruin that view with something that always covers those windows, so best to install window options that allow you to cover them on demand.

I have been experimenting with the Yellow option as I can open 30-40% of the room / glass, which I suspect when I measure will reduce the reflections, the problem then becomes the side reflections are very different.

Honestly the outside experience has me convinced that some decent trolleys and fine weather are the easiest criteria to meet. Window treatments will help, but the building construction is extremely light weight - thin walls and very poor isolation. So carpet, ceiling diffusion, wall/ window treatments will all be required to achieve something reasonable it seems.

And about to change speakers so that will be another learning curve. At least I have learnt how to measure things reasonably.......

 

[Harmonie]

Inside room measurements are here;

https://drive.google.com/file/d/1RsF9Fjky-gz-HI_Esa6oFE00YC2bXqpH/view?usp=sharing

I have a large memory foam 'bean bag' instead of a couch as it is far more absorbent / dampening acoustically (2m^3 of memory foam). But I agree the speakers are very tight and the off axis reflection from the wall behind spoiled the image/ sound unless listening almost nearfield. Outside where they can breathe they sound and measure much better - not surprising really.

Thank you but can't open it.
There are some windows users on this site ...

 

[Harmonie]

@Coach_Kaarlo
Just realized in your signature, your tiny hand-held, bookshelf speakers that you have or will have.
Nice speakers, I wonder if they fit in that room though.
Beware of your windows resonance ...

 

[Coach_Kaarlo]

Thank you but can't open it.
There are some windows users on this site ...

The link takes you to an REW file, so if you have the latest version of REW installed it should work?

 

[Coach_Kaarlo]

@Coach_Kaarlo
Just realized in your signature, your tiny hand-held, bookshelf speakers that you have or will have.
Nice speakers, I wonder if they fit in that room though.
Beware of your windows resonance ...

Indeed, they may well be no better or worse inside - but outside I expect they will be in a different league.

 

[Coach_Kaarlo]

Happy New Year all, hopefully whatever you celebrate or believe in there was music involved.


Absolutely wonderful to be able to relax and listen to music (and do some more measuring).

After much testing it seems I have found something of an acceptable compromise with my room.

The new Revel Performa3 F208's certainly seem to offer a good base to begin with, and moving them around is much easier than the Victor Laboratory speakers (96kg each) they currently replace. Running very short speaker cables (~250mm) has restored some damping factor, and with each amp bridged in mono there is enough power for the demands of the speaker I think.

There are so many reflections, and so much general brightness it really is difficult to find a place to even start in this room. A large thick rug, and more soft furnishings are on their way, but the memory foam bean bag does make a difference. Even though it makes the ETC worse I ended up measuring and listening with the room and windows closed, as the bottom end is much better.

So firstly I compared the DAC only to the DIRAC correction, shown below, to see if DIRAC does what it promises.

Blue = DAC only, Brown = DIRAC DSP

Interestingly DIRAC is able to boost the bottom end considerably without any major change in distortion. However there is a huge change in distortion around 50-60 Hz which is strange because according to DIRAC's measurements it is not actually boosting very much there at all, although the FR says otherwise.....

So to my questions;

1. I am concerned about the distortion as it leads me to believe the woofers are being over driven at those frequencies, even though I am essentially cutting all frequencies above about 30Hz with my correction curve. Should I locally reduce the correction at those frequencies based on the distortion? It is only the left channel which has the problem.
2. There is a difference in the noise floor between the DAC only and DSP measurements - could this also increase what REW measures as distortion?
3. The common and widespread advice on ASR is to correct with DIRAC only upto the transition frequency (which seems to be around 300-500Hz) however doing so would require boosting the bottom end of the target curve by a huge amount to get a frequency response which falls by 8-10Db between 20Hz and 20kHz. The speaker / room combination is mid range bright, and bass light. My conclusion therefore was to apply correction to the entire frequency range, using the bottom end 30Hz area as a starting point and cutting accordingly. Are there alternatives I have not considered?
4. Finally, how about 30Hz in room from the F208's?! Looking at the measurements it seems DIRAC is able to boost without over driving the woofers (based on the premise that over driving the woofers will eventually lead to increased distortion). I am impressed how sharp and clear the bass is, and how accurate the kick drum is FINALLY (all subjective of course) how much boost or correction is safe below 100Hz? +3Db or +5Db?? How much below 40Hz??

Overall, I am very happy with this current setup, it is of course overly bright when played loud. More room treatment will help, as will the new rug etc.

My only concern is around looking after the speakers and not over driving them.

 

[Harmonie]

Thanks for your feedback. It's nice to see before and after, since August.
It is only the left channel which has the problem.
Just wondering if the reason is not the curvy window on the left, opposing the right, that has a kind of wall.
running very short speaker cables (~250mm) has restored some damping factor,
You mean that your AHB2 were short of damping factor before ?? I also have like a foot long, speaker cable opposed to longer interconnects but do we hear the difference ?
Just a naive question: Did you tune by ear before tuning all with the Dirac ?
Again it's interesting to see the contrast with/without some furniture.
Do you have some picture with the Victor's that seemed really imposing visually ?

I'm pretty sure that the sound will change greatly once adding your final furniture.

 

[dasdoing]

red position in map looked pretty simetrical, the recent photo doesn't

 

[Coach_Kaarlo]

Thanks for your feedback. It's nice to see before and after, since August.
It is only the left channel which has the problem.
Just wondering if the reason is not the curvy window on the left, opposing the right, that has a kind of wall.
running very short speaker cables (~250mm) has restored some damping factor,
You mean that your AHB2 were short of damping factor before ?? I also have like a foot long, speaker cable opposed to longer interconnects but do we hear the difference ?
Just a naive question: Did you tune by ear before tuning all with the Dirac ?
Again it's interesting to see the contrast with/without some furniture.
Do you have some picture with the Victor's that seemed really imposing visually ?

I'm pretty sure that the sound will change greatly once adding your final furniture.

Perhaps the left speaker interaction with the curved window is contributing but it is conspicuously absent from the non-DSP measurement.

Yes. The AHB2 in mono with my cables has a minimum damping factor of ~50 @ 3.4 ohms with 3m / 10ft cable. Reducing the cable length to 300mm / 1 ft increases the damping factor to ~75 @ 3.4 ohms. In answer to your question about audibility I would suggest that at the lower frequencies the lack of driver control is audible, particularly because I have finally managed to reproduce the kick drum in my test tracks accurately with this current system and setup.

Yes, initially I tuned with ear, then with REW measurements. And I will look for some Victor pictures, might have some.

red position in map looked pretty simetrical, the recent photo doesn't

You are correct, the rear wall is angled in relation to the speakers, as is the left side wall. And the right wall finishes at half height and length. So what I have heard is a more consistent soundfield with this setup. I think the reflections in other speaker locations / setups create such a distorted image / tonality, that it is far better to compromise with some asymmetry. Also the main axis of the room runs this way so I can sit a a reasonable distance instead of effectively nearfield. The DSP sees a 0.02 m/s delay between the channels and 0.9 dB - so pretty close.

 

[Harmonie]

@Coach_Kaarlo
Thanks for teaching me the importance of direct damping factor related.
I think that this is what controls bigger diameter woofers.

 

[Coach_Kaarlo]

Some more tuning, and a new position for the speakers.

I am using the WIDE LOUNGE setting on DIRAC 3.0

Measurement cubes (x 3) each with a side length / width of 600mm, and a height of 250mm above and below the listening position.

Also I am using an overall cut with the B&K target which reduces the bass boost required to about +5dB - and full range correction.

Despite many advocating only using DIRAC below 300-500Hz, such generalisations do not consider the state of the bottom end in one's room. For example if I was to EQ with DIRAC and cut as required to boost bass response while maintaining reasonable distortion I would end up with a 10dB rise at 300 or 500Hz and ridiculous tonality. Instead it's necesary to cut the whole range and only boost the worst bass response by 5dB locally.

End result is then more correct tonaly, and also maintains the original distortion of the non-EQ'd speaker.

Bottom end close up.

Note - distortion largely unchanged, and much less stress on the driver at low frequency (under 20Hz), actually less distortion higher up due to the full range cut.

Weakest aspect is the inherent brightness of the room ,but at lower playback levels (70-80dB) the sound is coming along quite well - not at all fatiguing.