[WerTicus]

I have bluetacked felt to the front of the speakers with holes cut out for the drivers... i did this because i have read on here and elsewhere that it can make a difference by absorbing sound reflected off the front baffle.

Well i can tell you it does do that... and to my surprise made things sound clearer than i was expecting.

The cost of this mod was 4 dollars. it was worth every cent

[Tonto Yoder]

FELT? SO, YOU WANT FELT????

Whenever I hear about putting felt on the baffle, the little Spica's come to mind: it certainly was the extreme use of felt (both thickness and sq. footage)


When I first saw a grill-less Spica, I thought someone had DIYed the felt covering, but later realized that was the stock version.

I have a pair of older Infinity Kappa 6 speakers on which the entire baffle is covered with a thin black felt.

[WerTicus]

yeah i put on 2mm thick felt on mine - i imagine doubling the thickness shall bring some improvement further, but thats getting into the more than ten dollars area so i dunno if i am game

but none the less i can recommend anyone give it a try!

[doug s.]

kinda like the stock felt baffling on my meret re's.  tho a bit difficult to see in the foto, the felt is tapered 45 degrees at the drivers...



doug s.

[Jon L]

kinda like the stock felt baffling on my meret re's.  tho a bit difficult to see in the foto, the felt is tapered 45 degrees at the drivers...



doug s.

Nice speakers.  I haven't seen/heard Meret Re speakers in a few years.  Is the company still around?  Excellent-sounding speakers with those Nomex/Kevlar drivers and nice cabinet and a great value back then.

[orthobiz]

Just a personal anecdote:

I worked at Dahlquist in 1975. Someone wrote in that the speakers sounded better with felt on all four top baffles. For one week Dahlquist, Marantz and company were sequestered in the back listening room constantly listening to two pairs, one with felt and one without. They especially loved "Long Distance Love" by Little Feat.

One week later they emerged and decided that the felt version was not any better.

biz

[audioengr]

Werticus - I did this on my KEF reference 104/2s years ago and here is my experience.  Initially, it improved the image and detail.  However, what I discovered is that it is just a low-pass filter.  When I modded my components to eliminate sibilance, I found I could remove the felt and hear more music without losing any focus at all.  

If and when you eliminate the sibilance in your componentry, you will probably want to remove this felt.  It definitely eliminates some of the HF music, particularly HF echoes and ambient information that makes things more live sounding.

[doug s.]

1st, about the meret's.  unfortunately they're no longer made.  dunno what kelly cunnigham, its designer (and the designer of the artemos eos), is presently up to.  the re's, w/their constrained-layer cabinet construction, weigh ~45lbs each - quite beefy for such a relatively small enclosure.   they have withstood the test of time - i have had a wide variety of different speakers in that rig, & nothing yet has bettered 'em.  of course, i haven't tried anything really expensive, that mite give 'em a good run!     in any event, these are really nice, as are the cheaper ankh's, which i heard at an old s'phile show, & i was so impressed, i bought these off the 'net w/o having heard 'em.  there was a pair of ankh's f/a on a-gon recently, that got no bids at a no-reserve entry price of $380 - i dunno of anyting near that price that would give comparable sonics...

now, about the felt, i feel the design of a speaker has to be taken as a whole.  so, in some cases, adding felt may not be a long-term improvement.  but, if done like the meret re's - w/the felt tapered at a 45 degree angle, i feel it will aid a speakers' dispersion, regardless of what the material is.  but, even here, adding tapered felt could change a speakers' output, adding a horn-like loading effect.  but, as mentioned - it's relatively inexpensive, so it couldn't hurt to experiment.

doug s.

[WerTicus]

how can it be a low pass filter when i have cut holes for the drivers?

I would think it not be doing anything other than absorbing cabinet reflected sound and cabinet talk, both of which are not desirable

My system already has fairly good imaging and now it has better imaging.  I have also noticed an improvment in the clairity of the high end... which seems to be the result of the removal of this extra imformation that would be blurring the sound.

audioengr would you please explain your idea more!

and doug s, i have only applied 2mm of felt not thick felt like in these examples, i have also cut reasonable holes around the drives so as to ensure minimal interferance.

I just noticed i failed to mention that my drivers are not recessed and that the felt makes them pretty much flush now. (im sure this is a big factor!)

[doug s.]

how can it be a low pass filter when i have cut holes for the drivers?

I would think it not be doing anything other than absorbing cabinet reflected sound and cabinet talk, both of which are not desirable

My system already has fairly good imaging and now it has better imaging. I have also noticed an improvment in the clairity of the high end... which seems to be the result of the removal of this extra imformation that would be blurring the sound.

audioengr would you please explain your idea more!

and doug s, i have only applied 2mm of felt not thick felt like in these examples, i have also cut reasonable holes around the drives so as to ensure minimal interferance.

I just noticed i failed to mention that my drivers are not recessed and that the felt makes them pretty much flush now. (im sure this is a big factor!)

werticus, i'm w/you on this one.  except for some unknown synergy issues w/a particular design, (which is what my prewious post was referring to), i don't see how adding felt, especially how you did it, could do *anything* deleterious...

doug s.

[azryan]

"-i don't see how adding felt, especially how you did it, could do *anything* deleterious...-"

'Cuz it's only absorbing the high reflection.

It's not a low pass filter on the driver's output, but IS on the speaker's output which includes the reflection off the cabinet from the mids and lows not effected by the felt.

I think that's what audioeng. is meaning. That's at least that's what I'm meaning.

I'm not sayin' it's a crime to add the felt either.
To me it seems like just a diff. way to tweak the highs if you feel the need to.
 
Speaker and signal cables, x-over, diff. front end gear, etc... all ways to do this sorta thing.
Felt appears to be the cheapest and ugliest. hehe

Anybody feel like overlaying a fine sheet of black silk over the felt so they actually look good? It shouldn't alter the felt's effect.

[WerTicus]

yeah i used black felt it looks reasonably cool .... but its not totally tight and the cutouts are not perfect circles ... but its black on black so you cant really tell.

yeah i suppose your going to reduce the amount of HF reflections of the cabinet... oh wait that is what i did it to get!

Its definatly not making them quieter... if anything the highs stand out more now because of their extra definition.

[audioengr]

how can it be a low pass filter when i have cut holes for the drivers?

The physics of waveguides applies to speakers and acoustics.  You have put absorbing material inside the waveguide.  This is not as trivial as it seems.  It will filter the high frequencies.  Here is a loudspeaker company that really understands this:

[/url]http://www.4sptech.com/HTML/1024X768/home/index.htmhttp://

[quote]I would think it not be doing anything other than absorbing cabinet reflected sound and cabinet talk, both of which are not desirable [/quote]

No, the waveguide action includes the cones as well as the surrounding materials.

[quote]My system already has fairly good imaging and now it has better imaging. I have also noticed an improvment in the clairity of the high end... which seems to be the result of the removal of this extra imformation that would be blurring the sound.[/quote]

This was exactly my reaction when I tried this trick.  It was only much later that I discovered that it was only a low-pass filter.  Once your system extends well beyond 20 kHz in bandwidth and has no sibilance, you will get more music by removing the felt, trust me.  At the current state of your system, it is probably an improvement, but you may have several levels to go yet towards attaining audio nirvana.

[Aether Audio]

We appreciate the plug!!!

And yes folks, he is correct.  The issue is not trivial and on a deeper level, very complex.  If you're really good at calculus and higher math, the equations are all there (mostly).  We even have modeling software available that applies these equations, allowing the designer to make quick changes in cyberspace and observe the effects of those changes.  The models come close but slight modifications are usually required to tweak the response to optimized performance.

I will say that the application of felt and other materials to a flat baffle will help reduce spurious reflections but, as audioengr said, you are placing damping material in the waveguide and creating a low pass filter with a corner frequency somewhere.  As we have said on our website, all flat panels are essentially 180 degree waveguides at some frequency(ies).  As such, they are not really optimized for all the frequencies that are being projected from them.  There will always be compromises that cannot be avoided unless the fundamental error is corrected, i.e., the poorly designed waveguide action of the flat baffle.  That's why we at SP Technology use waveguides and that's why not using them produces these artifacts that you are all struggling with.

I wish I could give you all some direct algorithim to follow that will work while minimizing the negative effects of these damping materials, but I tried that route many years ago and was not successful.  My only recourse was to experiment with waveguides - and they worked.

It all comes down to physics and the underlying NATURAL LAWS of creation.  If we obey them we're rewarded, if we break them we pay the price.  Never the less, some form of bandage is better than an open wound so... good luck.  The effort is a worthwhile pursuit.

PS.  If you can aquire some form of testing software, microphone and sound card, you'll make the process much easier and achieve the most optimal balance of comprimises.

Take care all,:D
-Bob

[WerTicus]

Well this topic just got a hell of a lot more interesting!

my tweeter is the vifa dg25ag... metal dome -35khz

I do feel my most recent upgrade to pure film foil caps in the network with a bypass of the binding posts to have brought them to a level that is pretty much as good as they will get - certainly i cannot afford paper in oil.

So i will have to do some a/b ing to see if the felt is better not being present .  Perhaps these tweeters simiply are not good enough to produce the clairity.  They have ferro fluid after all.

But at least you guys have make me realise something i had no knowlege about and i will now read and read and read until i do And obviously take this into more serious consideration with my future set of speakers, rather than assuming its better, as seemed obvious to me before.

thanks!

[rosconey]

what about a circle of felt around the tweeter-my scan speak tweets have a foam front

[audioengr]

Werticus - you should try Multicap RTX polystyrenes or even their polypropylenes with tin-foil.  I have not found a better sounding tweeter cap.  The oil-caps are not even close....

[WerTicus]

a polystyrene bypass? because I was under the impression polystyrene was only available in very small values...

I used polystyrene in my amp actually as bypasses, and where what was required was only small values.

and rosconey i believe that is the most critical area.... being right next to the tweeters... though it could be 'good' for your case if your xover isnt using foil or polystyrene as audioengr says.  i would say the next level down, polypropolene to be too poor at getting the sound through.

[audioengr]

Werticus - you can get up to 1.5 uFd in Polystyrene from Multicap.  Just parallel them if you neeed more capacitance.

[rosconey]

the 8513 scan speak tweeters in my speakers are foam from the factory-
caps are solen