Felt Surrounds And Their Relevance To Single Driver Speakers

ZLS · « **on:** 12 Nov 2007, 06:49 pm »

I am the owner of the Omega Speakers Dipole XRS's that utilize the Hemptone 41/2" Drivers. I have previously owned speakers that utilized the Fostex 4" Driver and the Visaton B200 Driver. I read the posting of Jim Goulding and his Diffractionbegon felt surrounds. I inquired of Mr. Goulding as to the applicability of his product for single drivers, and ordered a pair. The result to say the least was very positive to my ears. Simply put, the sound is much sweeter with the surrounds. It is very clear that a distortion has been removed. The true character of the driver is easier to ascertain. I listened using two different amplifiers that emphasize different traits. A Red Wine Audio Signature 30.2 which is a warm involving extremely articulate amplifier. I also listened using a rebuilt Harmon Kardon Citation II amplifier which is a more analytical equally articulate and involving amplifier. Regardless of the amplifier used the positive effects of the surrounds was easily audible. The science is the same whether the driver is a tweeter or full range. In fact, I would go so far as to say that the effect would be more pronounced with a single driver because there is no place for the character of the driver to hide.
Quite frankly I was surprised by the positive effect of Mr Goulding product. The product was originally designed for tweeters, but is equally effective for single drivers.
There is science behind the reason the product works, and the price is reasonable.
The felt surrounds increased my listening pleasure, i felt it would be valuable to share this fact with other single driver speaker enthusiasts.
Thank you for your time

jrebman · « **Reply #1 on:** 12 Nov 2007, 07:43 pm »

Zack,

Thanks for letting us know about your experiences with the felt. I'm probably going to try it myself on at least one of my SD speakers at some point. I know floobydust has posted that his ported box for the FX-120 and now, F120A has the front of the box covered with cork, which has a similar, but probably not identical effect. The finish on my mini TQWTs for the FE- is a textured automotive paint, which again, is supposed to help with reflections off the baffle. Various other manufacturers, notably Sonus Faber, have used leather on the baffles of some of their speakers for the same reasons.

Hopefully some others will chime in with their experiences with these and other materials as well. I'm guessing that there must be some optimal coverage area and shapes, but what they are, I have no idea.

Good topic!

-- Jim

miklorsmith · « **Reply #2 on:** 12 Nov 2007, 10:14 pm »

I'll give it a try with my BFBs!

jimdgoulding · « **Reply #3 on:** 12 Nov 2007, 11:40 pm »

Permit me to interject, I am the designer/manufacturer of the product Zack is using. What I did for Zack, and do for all my customers depending on the speaker they use, was to make a surround for his speaker measuring 7" by 10" of high grade very dense real wool felt with a cutout for his driver that snugs up pretty close to the basket. I have made similar for Opera speakers that along with Sonus Faber use leather covered baffles with rave results. I believe that leather is a step in the right direction but only a very small step. Nothing in my experience to include neoprene and the kind of felt to be found retail will produce the kind of results Zach is getting or that you can expect using my product and labor. I guarantee this.

miklorsmith · « **Reply #4 on:** 12 Nov 2007, 11:52 pm »

The photos show tweeters only - the mids/woofers aren't treated. What frequencies would you expect to benefit with this felt?

jimdgoulding · « **Reply #5 on:** 13 Nov 2007, 02:31 am »

Mik- Hi. I am unfamiliar with the initials BFB. Is there a site I can visit where I can see your speakers? I estimate that on Zack's speakers with 10" wide cabinets frequencies above approx 3000Hz, perhaps lower, are interacting with his baffles. That's based on the length of sound waveforms. Make that were interacting with his baffles. I look forward to your reply.

JLM · « **Reply #6 on:** 16 Nov 2007, 10:00 am »

BFB is short for Big Fun Box: http://www.tnt-audio.com/clinica/bfb_e.html

Does the reflection of one baffle from the other speaker also benefit from use of the dense wool felt?

Frankly I'd expect the effect of the wool to be less in single driver designs because the relatively large cone would beam higher frequencies (4,000 Hz and above) and then act as a wave guide for the upper midrange (1,000 - 4,000 Hz).

jimdgoulding · « **Reply #7 on:** 16 Nov 2007, 03:40 pm »

Couldn't have said it better myself. That's what I would think, too. Zach is sort of a test case for me using single driver speakers. You might care to talk to him. He got ME excited! I was hesitant to offer my usual guarantee because of the custom work involved and because I didn't know what to expect but nothing ventured, nothing gained. So, if you would like to audition you may do so risk free on the condition that if you like them you keep them I just need to know the size of your driver and the distance from the driver basket to the top and sides of your baffle and distance to the port.

I'm sorry but I don't understand your first question? Are you referring to the rear firing driver? Please advise. Thanks. Jim

jimdgoulding · « **Reply #8 on:** 17 Nov 2007, 02:00 am »

Mik- From what I can tell from the picture you posted elsewhere of your BFB box, it would appear that you don't have much of a baffle to the sides of your driver to offend. I remain at your service if there is anything else I can do for you.

JLM · « **Reply #9 on:** 17 Nov 2007, 10:45 am »

Jim,

What I'm saying regarding baffle reflection is the soundwaves from the left channel hitting the baffle of the right channel speaker. It's been an issue with large baffle speakers (typically open baffles).

My particular speakers have a large vertically oriented oval shaped, with rolled edge, thickening of the baffle to shim the robust driver out (to make room for it inside and further reinforce):

http://geocities.com/rbrines1/Pages/FTA-2000/Main.html

So I'm not sure how you'd cut a piece of material for it.

jimdgoulding · « **Reply #10 on:** 17 Nov 2007, 01:25 pm »

In your case, I would have to do it by hand. I would use thick plush black wool felt sourced from another supplier to fill out the oval shaped raised baffle area with a cut out, obviously, for your driver. As for waveforms spreading out and interacting with the opposing speaker baffle, it should curtail this appreciably. Or, I could send you the raw material and you could do this yourself. I would purchase and include an affordable brand of scissors that would do this cleanly- not all will. To include shipping and the scissors, your costs will be $79.95. Let me know if you have any questions or would care to order in a PM. Thank you. Jim

Alwayswantmore · « **Reply #11 on:** 20 Nov 2007, 01:11 am »

Jim, do you have a web site or pictures of your product? Is the application reversable with no cosmetic damage to the speaker? Questions coming from an owner of Omega Compact Hemps with the newest 8" driver. Thanks, Kent

EDIT: I found the Web site: http://www.diffractionbegone.com/index.html -- The Compact Hemps use Omega's standard 8" Hemp driver with an embedded whizzer cone. Any thoughts as to how well your product would work for this application? Based on the size of the grill cover (horizontal diameter is only slightly larger than the spkr basket), I imagine to do any good your product could only be used with grill covers removed, correct? Thanks.

jimdgoulding · « **Reply #12 on:** 20 Nov 2007, 01:32 am »

Always- Can I get a look at your speaker somewhere online? Thanks.

Alwayswantmore · « **Reply #13 on:** 20 Nov 2007, 02:02 am »

Quote from: jimdgoulding on 20 Nov 2007, 01:32 am

Always- Can I get a look at your speaker somewhere online? Thanks.

Sure... http://www.omegaloudspeakers.com/compacthemp.html -- I have mine on the recommended Skyland stands, and use with an ACI Force XL sub.

jimdgoulding · « **Reply #14 on:** 21 Nov 2007, 04:36 am »

Always- I honestly don't know. I have only Zack's experience to guide me. But I'm filling an order as we speak for some Omega's very similar to yours and I sent you a PM about this along with some more info. Cheers.

jimdgoulding · « **Reply #15 on:** 21 Nov 2007, 05:47 am »

Always- I'm thinking, on second thought, that wasn't you I sent a PM to but another Omega user. Sorry about that. I think that for the greatest benefit, yes, we would want to extend coverage out beyond what I understand you to mean about your grill cover. Having said that, I don't know the size of your grill cover. Perhaps you would tell me.

richidoo · « **Reply #16 on:** 22 Nov 2007, 01:17 am »

Very interesting topic guys! I wanna check this felt out for my billboard sized baffle Legacys with twin tweeters!

But keeping with the thread topic, my Feastrex speakers have baffle side edges close to the drivers, but there is land above and below. Is wool felt applicable here? Very good high freq response on these drivers.

If you look close you can see cotton felt on the roof of the horn below the baffle. It eliminated a subtle horn honk. This principle is valid! Never thought about it on the baffle though.
Thanks Jim!
Rich

Alwayswantmore · « **Reply #17 on:** 22 Nov 2007, 01:10 pm »

Quote from: jimdgoulding on 21 Nov 2007, 05:47 am

Always- I'm thinking, on second thought, that wasn't you I sent a PM to but another Omega user. Sorry about that. I think that for the greatest benefit, yes, we would want to extend coverage out beyond what I understand you to mean about your grill cover. Having said that, I don't know the size of your grill cover. Perhaps you would tell me.

Sorry I did not respond earlier. I am not at home this week. But when I was home I tried sliding the grills back and forth on the horizontal plane. There was less than an inch give, meaning -- at least for the sides of the front baffle -- there is no room to put
felt. It would probably mean leaving the grills off, or have felt that could be easily attached / removed, and only use felt on for serious listening.

Interesting topic and I will continue to learn from others experiences here. Also looks like a very modest priced tweak, so I'm very interested in it.

ZLS · « **Reply #18 on:** 25 Nov 2007, 01:44 pm »

I thought that I would check in again with an update. I ordered an received a second pair of the felt surrounds for my backward firing 4 1/2" driver in my diploe configuration. I communicated with Mr. Goulding as the the effect I could expect by such an addition, and he was quite truthful in saying that the effect would not be as dramatic as the surrounds on the front firing speaker. This is correct, however, I do hear a change for the positive. The sounds seems clearer and more coherent and I can hear deeper into the soundstage. Perhaps this is because I now have an identical sound coming out of both the front and rear driver The change is subtle, but my enjoyment of my music has increased. I realize that this has limited applicability to many who read this particular forum, but I can't help but wonder about two things.

1. The applicability and effectiveness of using the surrounds on the rear of the driver in an open baffle configuration?
2. The applicability of using the surrounds on the rear of the driver in a sealed box configuration. I understand that the maker of the speaker would have to do this, but some of you guys build your own speakers so I am curious as to what would happen.

Summing up, not a great effect but definitely a good one. IMHO the cost/benefit analysis while a no brainer for the front firing drivers; is still clearly positive for the rear firing speakers. I have spent a lot more for a lot less of a positive effect.
Just one person's opinion based on his experience.

Alwayswantmore · « **Reply #19 on:** 25 Nov 2007, 03:41 pm »

Quote from: ZLS on 25 Nov 2007, 01:44 pm

I thought that I would check in again with an update. I ordered an received a second pair of the felt surrounds for my backward firing 4 1/2" driver in my diploe configuration. I communicated with Mr. Goulding as the the effect I could expect by such an addition, and he was quite truthful in saying that the effect would not be as dramatic as the surrounds on the front firing speaker. This is correct, however, I do hear a change for the positive. The sounds seems clearer and more coherent and I can hear deeper into the soundstage. Perhaps this is because I now have an identical sound coming out of both the front and rear driver The change is subtle, but my enjoyment of my music has increased. I realize that this has limited applicability to many who read this particular forum, but I can't help but wonder about two things.

1. The applicability and effectiveness of using the surrounds on the rear of the driver in an open baffle configuration?
2. The applicability of using the surrounds on the rear of the driver in a sealed box configuration. I understand that the maker of the speaker would have to do this, but some of you guys build your own speakers so I am curious as to what would happen.

Summing up, not a great effect but definitely a good one. IMHO the cost/benefit analysis while a no brainer for the front firing drivers; is still clearly positive for the rear firing speakers. I have spent a lot more for a lot less of a positive effect.
Just one person's opinion based on his experience.

One more potential application: Some single drivers, Compact Hemps included, have rear firings ports. I wonder it the rear port might also benefit?