I know you asked for "matching", but the "tights from Tesco" hack for 8000's was so good, I must bring it to your attention: /forum/imported-unmapped/beolab-8000---recloth-frets-for-less-than-10gbp#post-2199866

In addition to the usual speaker DIY firms, consider the incredible variety of acoustic cloth from Guilford of Maine: https://www.guilfordofmaine.com  Their well-known "FR701" in black is available from many places.  (Probably not the B&O OEM since it's US-based, yet it was used "everywhere" in decades past.)  But just imagine the custom coolness (and WAF) of "Coastline" in Vapor Blue...  

This is great stuff. I’m looking to keep them as close to original as possible.

trackbeo wrote:

In addition to the usual speaker DIY firms, consider the incredible variety of acoustic cloth from Guilford of Maine: https://www.guilfordofmaine.com  Their well-known "FR701" in black is available from many places.  (Probably not the B&O OEM since it's US-based, yet it was used "everywhere" in decades past.)  But just imagine the custom coolness (and WAF) of "Coastline" in Vapor Blue...  

Hi,

It looks to me like their "Acoustic Cloth" options are all for putting in front of absorbers (and have significant absorption coefficients according to the graphs that I've looked at on their site...)

What you need in front of a loudspeaker is transparency - so I'd be looking for an absorption coefficient of 0 at all frequencies in a best case.

Or am I missing something?

-g

You are not wrong, looks like the stockings/leggings is the way to go as I still haven’t found other more transparent options. You know if any?

Geoff Martin wrote:

It looks to me like their "Acoustic Cloth" options are all for putting in front of absorbers (and have significant absorption coefficients according to the graphs that I've looked at on their site...)

What you need in front of a loudspeaker is transparency - so I'd be looking for an absorption coefficient of 0 at all frequencies in a best case.

Agreed, but an absorption coefficient of zero at audio frequencies is not possible, is it?  Warp & weft (threads per inch), and tensile strength of the yarn, all have to be non-zero.  Isn't that why audiophiles are always removing their speaker grilles?  (To light frequencies of course they are very absorptive, say, 35-50%, that's why we use them after all.) 

Yes, the Guilford fabrics are intended for office sound-absorbing panels.  But panels have their own particular engineered characteristics, so the requirement for their fabrics is that they *pass thru* as much of the sound as possible to the panel behind!  The two bugs are: (1) they feel that "a little" absorption across all frequencies is not a bad thing (as you pointed out), and (2) they only really care to measure in the 300-3000 Hz range because that's what office-furniture manufacturers want to catch.  That said, the "FR701" looked closer to zero than the rest of their line, and looked (comparatively) flat.  Question: Let's imagine that we have a fabric which is miraculously flat across the audio frequency spectrum, but has significant non-zero absorption.  Yet if I turn up the volume, am I not simply overcoming that absorption (and generating a bit of heat)?  Nothin' wrong with that...  Or is there?  (No fabric will be flat, but I would guess a sort of band-pass with a slope at one end, which can be EQ'ed away?)

Geoff, are there graphs for the Kvadrat fabrics used by B&O?  They look rather "wooly", which I take as frizzy at the surface, which I then take as a proxy for sound-absorbing at mid and high frequencies -- but I'd love to be proven wrong.  Maybe the original poster should be buying those!

Yet surely those fabrics are better than metal grilles with little holes punched in them, which must be 50% reflective (for short wavelengths) right back at the source!  For that matter, I'm suspicious of lamellas, which, placed at varying angles as they are, intuitively seem to be creating a huge reflective comb interference filter!  (Or does 1" by 1/4" put them outside the frequency range of the drivers they're hiding?)  Of course intuition is no substitute for science, which itself is no substitute for measurement of the results!  Sorry to veer off topic, but I'm curious to know how or why lamellas aren't a really bad idea...  [[EDIT: I was thinking about the Beovisions where the metal grilles and lamellas cover full-range speakers.  In the BeoLab 18s and 50s, the crossover frequency to the acoustic lens could put them out of the range of any interference.  So ignore the "placed at varying angles" bit.]]

So what fabric would you use on pentas?

Geoff Martin wrote:

trackbeo wrote:

In addition to the usual speaker DIY firms, consider the incredible variety of acoustic cloth from Guilford of Maine: https://www.guilfordofmaine.com  Their well-known "FR701" in black is available from many places.  (Probably not the B&O OEM since it's US-based, yet it was used "everywhere" in decades past.)  But just imagine the custom coolness (and WAF) of "Coastline" in Vapor Blue...  

Hi,

It looks to me like their "Acoustic Cloth" options are all for putting in front of absorbers (and have significant absorption coefficients according to the graphs that I've looked at on their site...)

What you need in front of a loudspeaker is transparency - so I'd be looking for an absorption coefficient of 0 at all frequencies in a best case.

Or am I missing something?

-g

I have actually wondered about to what extend you account for the absorption coefficients of the fabrics (especially with the Beolab 50, which have cloth and wood/metal options). I guess with the Beolab 50 you always need to have a cloth front? Could you actually publish the absorption sweep for the cloth used by B&O? I have used cloth from Akustikstoff.com, who actually publish the sweep signal with different kinds of cloth (sadly only in German: https://www.akustikstoff.com/media/products/0900591001442653810.pdf). Would you say this fabric is "close enough=good enough" to use with B&O speakers (not kvadtat)? 

P.S. I thoroughly enjoy reading your blog!

I recently rebuilt a pair of Tannoy PBM-8 speakers and used the Jet Black cloth from Simply Speakers. They are US based, but perhaps there is a more local supplier in your area. This fabric is pretty much a "dead ringer" for the original cloth. I can't say how it matches in your instance, but I admit that in my case I like it.

Details at: https://www.simplyspeakers.com/speaker-grill-cloth-fabric-black-a-569.html

Regards,

Welcome Roger - now we have (at least) 2 Rogers on the Forum....one in Norway and you.

MM