Acoustic properties of glass

[Miguelón]

Hi everybody!

I recently bought some Genelec monitors which have onboard shelving low filter (-2, -4, -6 dB).
They are placed on floor stands with some big window and glass door behind.

Genelec advices to use the with -4 dB low pass in order to compensate wall relfexions, but by ear I find them more natural at -2 dB (I’m looking for a mic ro room measurements).

Just by curiosity, do anyone know how glass abosrbs and reflect lows and other frequencies compared with a brick wall or similar?

 

[Jim Taylor]

This may (or may not) help you:

Jim

 

[Vladimir Filevski]

Glass absorbs part of the lows and strongly reflects mids and highs. Brick wall strongly reflects everything.

 

[LTig]

Glass absorbs part of the lows and strongly reflects mids and highs. Brick wall strongly reflects everything.

That explains why the OP prefers -2 dB over -4 dB.

 

[Miguelón]

That explains why the OP prefers -2 dB over -4 dB.

Thanks! Yes, lows didn’t sound as strong as expected near a wall, and mids were so uncomfortable.

Now I tried “desktop mode” on both speakers and they even sound better (I think the setting is -4 dB around 160 Hz)

They are also some wood on the structure of the door and windows so perhaps work more as a table than as a wall

 

[dualazmak]

Glass absorbs part of the lows and strongly reflects mids and highs.

Agree, and this is why I recently started my new series of audio experiments using hard-heavy random-surface Bohemian glass for wide-3D reflective dispersion of metal-horn super-tweeter sound;

- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-1_ Background, experimental settings, initial preliminary listening tests: #912

- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-2_ Comparison of catalogue specifications of metal horn super-tweeter (ST) FOSTEX T925A and YAMAHA Beryllium dome tweeter (TW) JA-0513; start of intensive listening sessions with wide-3D reflective dispersion of ST sound: #921

 

[restorer-john]

Agree, and this is why I recently started my new series of audio experiments using hard-heavy random-surface Bohemian glass for wide-3D reflective dispersion of metal-horn super-tweeter sound

You should try a Waterford cut lead crystal whiskey glass with half a glass of whiskey in it. Drink the first half before you start.

 

[dualazmak]

You should try a Waterford cut lead crystal whiskey glass with half a glass of whiskey in it. Drink the first half before you start.

View attachment 367633

Thank you for your nice suggestion. Yes, I (we) also have that type of whisky glasses and flower vases.

I am quite weak, however, for alcoholic drinks especially whisky and brandy even though I very much enjoy the flavor of them.
I have analyzed/measured my gene and found that I have homo-deficiency of gene for aldehyde dehydrogenase enzyme; this often happens in Japanese and other Asian people who have red-flash in face with alcohol and become sleepy (sometimes very happy to be so, though) .

Furthermore, the homo-deficiency of that gene means I would never become stronger for alcoholic drinks even how eagerly I would "train" myself for it!

Consequently, I should be better to eat healthy fresh salad with the nice Bohemian glass salad bowl every time before I would start the session of my new series of audio experiments (with my non-alcoholic clear ears and brain); fortunately, my wife well agrees and she is ready for it!

 

[Miguelón]

Agree, and this is why I recently started my new series of audio experiments using hard-heavy random-surface Bohemian glass for wide-3D reflective dispersion of metal-horn super-tweeter sound;

- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-1_ Background, experimental settings, initial preliminary listening tests: #912

- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-2_ Comparison of catalogue specifications of metal horn super-tweeter (ST) FOSTEX T925A and YAMAHA Beryllium dome tweeter (TW) JA-0513; start of intensive listening sessions with wide-3D reflective dispersion of ST sound: #921

View attachment 367607

Are you using a salad bowl as a wave guide or something like that?

Funny, perhaps with adding a pressure cooker as a woofer we can made a whole range speaker low cost at home.

When 2020 confinement I found myself in a terrible situation isolated with no music reproductor at all, and saw on YouTube someone that showed than putting the phone inside a bowl you can increase loudness and improve frequency response. He saved my life!

I hope Amir will soon review the device: “Smartphone (model and year) inside a salad Bohemian glass bowl” to show harmonic distortion at 80 dB SPL and FQ curve. Perhaps spectral decay to investigate resonances

Seriously, thanks for all contributions, the Genelecs sounded a little bit brighter than expected and now I understand why.

 

[Jim Taylor]

Funny, perhaps with adding a pressure cooker as a woofer we can made a whole range speaker low cost at home.

Only slightly OT: Why spend all the money for a pressure cooker?

https://www.edn.com/make-great-sounding-40-bucket-speakers-in-an-afternoon/

Not enough bass? Try this:

Bucket Sub

Worlds cheapest best subwoofer project

transcendentsound.com

These people are nothing if not resourceful!

Jim

 

[Pareto Pragmatic]

Glass absorbs part of the lows and strongly reflects mids and highs. Brick wall strongly reflects everything.

I will add that it does depend somewhat on how thick the glass is, how big or small, and importantly how solidly it is connected to surrounding material.

Let's just say I have a few 100 year old bits of glass here and there (door windows mainly), and they move a LOT more than the 60 year newer replacement windows.

 

[Pareto Pragmatic]

Agree, and this is why I recently started my new series of audio experiments using hard-heavy random-surface Bohemian glass for wide-3D reflective dispersion of metal-horn super-tweeter sound;

I have used curved vases before, for small improvements from dispersion here and there in a way that fits the room decor, but never thought of cut glass. That makes a lot of sense.

Time for a trip to the thrift store! Because cut glass should work better than smooth(ish) ceramic. Given that my wife's art sits in vases, even if it does no good they won't go to waste.

 

[Miguelón]

https://www.edn.com/make-great-sounding-40-bucket-speakers-in-an-afternoon/

Slightly disappointed because it is a passive speaker (but the “in garden response” is nicely flat for the moles).

Why he don’t try an Active Bucket?

 

[Mart68]

Are you using a salad bowl as a wave guide or something like that?

Funny, perhaps with adding a pressure cooker as a woofer we can made a whole range speaker low cost at home.

When 2020 confinement I found myself in a terrible situation isolated with no music reproductor at all, and saw on YouTube someone that showed than putting the phone inside a bowl you can increase loudness and improve frequency response. He saved my life!

I hope Amir will soon review the device: “Smartphone (model and year) inside a salad Bohemian glass bowl” to show harmonic distortion at 80 dB SPL and FQ curve. Perhaps spectral decay to investigate resonances

I always thought this was a pretty clever idea. There's multiple variants:

 

[Miguelón]

I always thought this was a pretty clever idea. There's multiple variants:

Seem like the “Neumann’s Mathematically Modelled Dispersion™ (MMD™) waveguide” on the KH 120 ii model.

Even better, because don’t need DSP phase alignment and is clearly co-axial

 

[dualazmak]

Are you using a salad bowl as a wave guide or something like that?

No, not at all.
I use the outer random cut-glass surface of the heavy-thick Bohemian salad bowl as "wide-3D reflective dispersion material" only for metal-horn super-tweeter's high Fq sound; yes, I am rather serious on the experiments.

If you would be seriously interested, please read most carefully my post here and my posts thereafter;
- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-1_ Background, experimental settings, initial preliminary listening tests: #912

 

[Miguelón]

No, not at all.
I use the outer random cut-glass surface of the heavy-thick Bohemian salad bowl as "wide-3D reflective dispersion material" only for metal-horn super-tweeter's high Fq sound; yes, I am rather serious on the experiments.

If you would be seriously interested, please read most carefully my post here and my posts thereafter;
- A new series of audio experiments on reflective wide-3D dispersion of super-tweeter sound using random-surface hard-heavy material: Part-1_ Background, experimental settings, initial preliminary listening tests: #912

I understood only a little part of the article, but is admirable the role of the salad bowl to wider the super tweeter angle (and those without causing your wife to accomplish some domestic vague menaces )

I didn’t know the existence of super tweeters before but since I red from a link on the thread, probably I wont perceive any difference (limited to 15 kHz actual hearing capacity) or if perceived then the cost of the ST plus the Bohemian glass bowl will overcome my budget!

I also was curious about the highest role of auditive spectrum, the last note on my piano is about 3.500 Hz or so, and is difficult to imagine two octaves higher than this

 

[dualazmak]

I didn’t know the existence of super tweeters before but since I red from a link on the thread, probably I wont perceive any difference (limited to 15 kHz actual hearing capacity) or if perceived then the cost of the ST plus the Bohemian glass bowl will overcome my budget!

Sorry, but again I need to say "no" for you.

If you look and learn very carefully on my Fig-12 and Fig-13 in my that post, you can understand that my tweeters and super-tweeters are singing together "audibly" in Fq zone of around 5 kHz to 20 kHz.

 

[dualazmak]

I also was curious about the highest role of auditive spectrum, the last note on my piano is about 3.500 Hz or so, and is difficult to imagine two octaves higher than this

My another thread "Music for Testing Treble (High Frequency) Sound", especially post #1 there, would be also of your reference and interest, I assume.

 

[CINERAMAX]

Our niche predominantly focuses now on Point Source Coaxial Limited Channel Count (<9.x.6) Atmos, Videowalls, and Windows. We've gathered predictive and measurement data indicating that, generally, some bass frequencies pass through the windows. In a room equipped with 39 loudspeakers and 7 subs, the RPG ModViewser transparent diffusers have been installed to cover the glass. Additionally, there are on the market perforated sound-absorbing glass transparent panels. To mitigate unwanted reflections caused by the large videowall and extensive glass surfaces, it's advisable to position rear speakers sideways rather than directly facing the videowall.

curiously the frequencies below 70-80 may not be permeating through the glass.