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Acoustic consultancy

Bjorn

Major Contributor
Audio Company
Joined
Feb 22, 2017
Messages
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Location
Norway
I represent sound & acoustics and offer different acoustic services. We sell RPG products and also offer custom ones of these that are not seen online.

Some examples of services and prices:
1. Acoustic consultancy for one week via email with advice for acoustic products we sell and how to measure the room in regards to room modes and choosing type of bass trapping and its placement. Price 3000 NOK (not tax/VAT outside of Norway). With today’s currency that’s about $279 or 255 Euro.

2. Same as above, but also includes tips how to build your own absorbers and bass traps with porous material (not diffusers or pressure based traps). Price 5000 NOK for one week. With today’s currency: About $465 or 426 Euro

Both can be renewed with another week for the same price if more time is needed. Or if you believe you need more time, a set price for a certain time span can be agreed on.

I can also assist with finding best placement in room for speakers and listening position, integration of subwoofer and use of DSP/EQ. This normally takes a bit more than a week for most.

Will need information like:
Room dimension, placement of speakers and listening position, pictures of the room and especially if the goal is to treat lower frequencies you should be able to measure with REW and send the measuring file. If you plan to address sub frequencies with pressure based traps measurements is also required. However, if you simply generally want to improve the bass above approximately above 90-100 Hz we get a long way without measurements.

Measurements are needed in regards to subwoofer integration and finding optimal placement.

Experience:
I’ve worked professionally with room acoustics since 2015 and have years of practical experience before that. I’ve assisted both audiophiles with stereo setups, surround systems, recording/mixing studios, and homes with general improvement of acoustics besides larger venues.

I have practical experience with several small room acoustical principles and have tested various products and different types of treatment over many years.

I’m also involved in developing speakers and have good understanding of speaker designs.

Goal:
I listen to what the customer desires in order to choose the right treatment. A good sounding space isn’t necessarily the same as an accurate listening environment for everyone. Perhaps you want something more on the spacious and enveloping side instead of highly accuracy with hearing the mix as detailed as possible. It may also depend on what type of treatment you can live with, aesthetics, where you can place treatment and budget. My goal is to assist in this and tell you what you can experience with different types of treatment.

What can you except?
Will obviously depend on treatment and surface covered but generally, we should see an improvement in:

- More even frequency response, if the treatment is sufficiently effective

- Less specular energy with the result of greater clarity, intelligibility, more correct tonality, smoother sound with less listening fatigue

- Great envelopment and a larger image/ increased spaciousness if diffusion or hybrid diffusion/absorption is used

- Less resonances with the experience of less muddiness, tighter bass and often the experience of a bass that is “quicker” and gives more “slam” due to a shorter decay and less ringing. This can also clean up the midrange and treble

What you cannot expect:
- If you have large deviations in the frequency response, little treatment isn’t going to even this out. Especially for sub frequencies, treatment needs to be quite large and cover much surface area for major improvement in the frequency response. Some bass trapping will still improve the time domain though with a shorter decays and less resonances, which may be quite audible. But adding a few smaller bass traps will not flatten the response much. Frequencies above 100 Hz is easier to treat but generally still requires more than a few panels for big changes in the response. But again, the domain will improve and the importance of this is often overlooked by many.

- If you only have certain areas where you can place treatment and they happen to be at places where there are no arrival specular energy from or it’s isn’t at a pressure point for low frequencies, treatment will generally not help much at your listening position. It may help more other places in the room, but for the “sweet spot” it may be a waste.

- I don’t consider the reverberation time in a small room. It’s well established in the small room acoustical community that RTx measurements are not valid in small rooms. Just because the number goes down with added absorption doesn’t mean the equation is correct and gives a good picture of a well designed listening space. RTx graphs can be very misleading in a small acoustical space. You can read more about this here: https://www.lydogakustikk.no/en/small-rooms-and-reverberation-time/
Whether you look at these measurements yourself is of course up to you, but it’s on focus area for me at all

- In the past I’ve offered some drawings and renderings of the room with acoustic products, but it’s something I have stopped doing. While this may look cool, it generally doesn’t give a very accurate presentation of the colors, fabric, and aesthetics. It’s better for me for example to send you color swats of fabrics if you are uncertain about which fabric color to choose. 3D drawings also takes up time that can be used better for something else


Questions and answers:
- How do I pay?
Payment is in advance where I sent an invoice to you email address, and I prefer using Wise for transfer. Wise works as paypal but is considerably cheaper. https://wise.com/
If you want to use paypal I would need to add a fee of 3%.
Wire transfer is also ok to use if you live in Europe.

- Can you also advice in commercial products from other vendors?
Especially if you live in an area where we can’t sell you the products that we offer, yes I can. I have a good knowledge about many other brands and products and have also tested some of these. Some are good and some are not

- Can I not simply use EQ?
EQ is a powerful tool when used correctly. However, it cannot replace physical treatment in a room because most of the room response isn’t minimum phase behavior, it can’t add diffuse energy, remove flutter echo or minimize comb filtering. The best is always to do the treatment you can do and apply equalization carefully at the end. EQ of dips and peaks of the room response that is not minimum phase should generally be avoided, especially above the Schroeder frequency


Contact info: [email protected]
 
Your room is wide enough for diffusion on opposite side wall reflection points, something that will create a very large, spacious and addicted result with a broadsband diffuser. I'm no fan of short horns because they loose the vertical directivity high in frequency. I strongly believe in having broadband constant directivity, which means very big horns. If not, I think there are other speaker designs are better than horns.
Thanks for offering consultation services which may be helpful once a specific horn and driver are selected for the following two-way system for use in my room:

While those polar plots and other measurements look wonderful, the speaker in post #3 would not be an option for me, as its size and possible cost look beyond what I could manage. https://www.audiosciencereview.com/...audio-midrange-horn-polar-measurements.42732/

What I need is the best alternative constant directivity horn and which can safely set atop these sealed 15” midwoofers. See attached photos and sketches.

The sketches are from Gary Dahl, Lynn Olson’s friend, who kindly shared them and other photos for me to clone his Altec 416-8B midwoofers. Troy Crowe presently has them for building a two-way horn system. https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed

Three or four Rythmik subs will be used with them. https://www.rythmikaudio.com/F12.html

So, whichever horn you might recommend it would need to sit atop and be fully compatible with these midwoofers. Troy Crowe will need to design and build the two-way passive crossovers, though I may eventually experiment with active analog crossovers.



Referring to the very crude sketch of my room attached, I am hoping the speakers could be successfully placed diagonally between the east wall and the open hallway opposite the kitchen area, with me sitting ~ 11 ft away.

Unless you have a specific constant directivity horn recommendation (s), please rate the following:






Thank you.
 

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Thanks for offering consultation services which may be helpful once a specific horn and driver are selected for the following two-way system for use in my room:

While those polar plots and other measurements look wonderful, the speaker in post #3 would not be an option for me, as its size and possible cost look beyond what I could manage. https://www.audiosciencereview.com/...audio-midrange-horn-polar-measurements.42732/

What I need is the best alternative constant directivity horn and which can safely set atop these sealed 15” midwoofers. See attached photos and sketches.

The sketches are from Gary Dahl, Lynn Olson’s friend, who kindly shared them and other photos for me to clone his Altec 416-8B midwoofers. Troy Crowe presently has them for building a two-way horn system. https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed

Three or four Rythmik subs will be used with them. https://www.rythmikaudio.com/F12.html

So, whichever horn you might recommend it would need to sit atop and be fully compatible with these midwoofers. Troy Crowe will need to design and build the two-way passive crossovers, though I may eventually experiment with active analog crossovers.



Referring to the very crude sketch of my room attached, I am hoping the speakers could be successfully placed diagonally between the east wall and the open hallway opposite the kitchen area, with me sitting ~ 11 ft away.

Unless you have a specific constant directivity horn recommendation (s), please rate the following:






Thank you.
One has to consider the speaker and the room together. If your goal is a high degree of spaciousness, the directivity of the speaker combined with the room and what treatment you can apply needs to be looked at as a whole.

As for the type of horn, besides the part about room integration and design goal of type of sound, it's also a matter of size and budget. Certain horns work better with certain dimensions.

If you're interested in consultancy related to this, please contact me: [email protected]
 
In order to decide on the type of horn for a spacious sound, and a horn which also works superbly across all other subjective listening parameters-3D sound stage size, vocal clarity, accuracy of musical instrument timbre, instrument and vocal imaging, et al-would it be necessary for me to first measure the room in regards to room modes and choosing type of bass trapping and its placement? Instead, I'm hoping that this could be done after the system is built and installed, to then select materials to overcome the room's acoustical issues.

If yes, then to select the horn for a two-way system might you only need be a detailed sketch of my living room-and all on the westside the adjoining open hallway, staircase and small kitchen? Assuming the attached is quite crude, what other info would be required?
 

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While off topic, I am curious about your work long ago with Lynn Olson regarding the development or modification of the JMLC AH425 horn. What led to that collaboration?
What changes did you make to the original JLMC design and what were the goals in doing so?

Was it mostly one sided on Lynn's part, or did you once have a listening preference for the "direct" sound presentation of such a relatively high directivity horn?
 
In order to decide on the type of horn for a spacious sound, and a horn which also works superbly across all other subjective listening parameters-3D sound stage size, vocal clarity, accuracy of musical instrument timbre, instrument and vocal imaging, et al-would it be necessary for me to first measure the room in regards to room modes and choosing type of bass trapping and its placement? Instead, I'm hoping that this could be done after the system is built and installed, to then select materials to overcome the room's acoustical issues.

If yes, then to select the horn for a two-way system might you only need be a detailed sketch of my living room-and all on the westside the adjoining open hallway, staircase and small kitchen? Assuming the attached is quite crude, what other info would be required?
Measuring room modes isn't necessary to choose the horn. But the rooms layout, where treatment can be placed and not be placed is important in regards to the type of horn and design goal. And the horn type depends also on the size and budget. Obviously room modes also effects areas like clairty and timbre, but this will be realted to optimal placement, treatment and possibly EQ.

Emailing with an order with the mentioned info and sending pictures of the room is needed in order to start. Please do this by email and not in this thread.
[email protected]
 
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