Diffraction elimination

[Filterlab]

Like most audiophile chaps, I'm definitely up for a tweak which is preferably all of the following things:

1. Effective
2. Easy to install (i.e. doesn't require a degree in electronic engineering!)
3. Cheap.

So as if by chance the perfect tweak offer dropped into my lap seemingly out of nowhere! After extensive listening and loving of my Revel M22s and having tried them on different surfaces and with different cables etc etc I was very VERY pleased with their performance, surely nothing could make them even better?

Well yes actually, and for a darn sight less than they cost to buy. In fact an amazing tweak was had for just 1.4% of the price of the speakers. YES! For £28 including taxes and shipping, my esteemed acquaintance Jim from diffractionbegone created a pair of baffle covers to perfectly fit my speakers.

So the science is not really up my street, but what I can hear are the effects of a scientific principal working in my favour, and boy can I hear a difference with these things! Have a look and see how they fit, and I'll tell you how they effect (read as 'improve') the sound.







Now you may balk a little at the looks, but in the flesh they look superb and if I'm honest the looks have really grown on me. However, it's not about the looks I hear you say. So the sound...

Well my friends, the difference these things have made is nothing short of staggering. I was expecting it to effect the treble, but in actual fact it's quite the opposite.

The first thing that really struck me was the midrange clarity - think 'crack of the snare', 'clap of the hand' and 'strum of the guitar' and you're on exactly the right lines. The focus in this audible region has to heard to be believed, but that's not all - oh no! The other amazing element is in the bass lines, particularly bass guitar, which takes on a start/stop nature that is as tight as the deft handwork as any talented guitarist. Again I'm going to use the superlative 'focus', clarity in this region is so improved, amazingly in fact.

So is that it? Nope, there's two other areas which are even more impressive, namely imaging and vocals. Imaging on my Revels was always a little bit of a sticking point after owning some Martin Logan electrostats, but these baffle covers have augmented the imaging to near-electrostat levels, and that's saying something. I guess this is why vocals sound sooo good, they just stand so clear from the mix with such audibility and yet never become overblown.

When I discussed my findings with Jim he was glad that I 'got it' and clearly the aim of his product is exactly as I found.

If you have thirty quid that you fancy putting towards a positive tweak in your system, you'll NEVER go wrong with these.

[jimdgoulding]

Rob- You know I’m glad you appreciate it. The science taking place is that your surrounds are neutralizing waveforms above your crossover from interacting with your speaker baffles. That belated interaction is responsible for a second wave of the same information to your listening position and nearby walls. The removal of this allows your system to more faithfully reconstruct instruments and space as captured by the microphone in your room. Even off axis there is a benefit in the frequency domain. A truer signal translates to truer information and the result is that instruments and vocals and the space that surrounds and separates is simply truer, as true as your system is capable of delivering. Nice surprise, huh.

[Robson]

Well said Jim......diffraction and the baffle have always been a difficult subject and why I cover my cabinets in leather and soften the edges which I believe yields benefits over highly lacquered cabinets. The new Wilson Duette has tried to tackle this problem with a section on the tweeter......people will do any-thing to justify a £10k+ price.

[jimdgoulding]

With your permission, I thought I would add just one customer review sent to me personally to go along with Filterlab's review above. This is from a man who primarily listens to classical music using some 3 way custom built towers:

"Hello Jim:

Here are my comments.

With the felt tweeter surrounds, there is less smearing of the sound; in orchestral music, individual instruments can be heard distinctly rather than blending into an amalgam of sound. There is definitely more depth to the sound stage and more hall ambience as well. Rather than a sound stage laterally restricted about each speaker and the virtual center, the felt tweeter surrounds produce a soundstage width that is more uniform and panoramic. My preferred room curve using a 1/3 octave RTA/equalizer previously required a roll off of 1.5 db per octave between 4KHz and 10KHz to avoid a brittle treble. With the felt tweeter surrounds in place, I find the room and my ears tolerate a flat response in that frequency region. This relative frequency boost may also contribute further to the perceived improvement in the size and depth of the soundstage. The applause, however, are my own. Thank you." Irv Bloom- Oceanside, CA

I would just add that his realization of "a brittle treble" in his room before trying this was not due to his driver or electronics. It was due to what was taken away.

It would be my pleasure to share your review, too, if you're not too bashful, that is, those of you for whom this mod will benefit similarly.

All the best.

Jim

[jimdgoulding]

Think I’ll add another one. A boy has gotta do something to keep this in front of you. This is from a fellow down under using Osborn Eclipses, an aussie speaker previously unknown to me. You boys don’t forget that everything upstream of your drivers and speaker baffles is ultimately delivered to you by sound waveforms. Best you look after them. They contain information worth preserving. Know what I mean? If you're not sure, I'll answer questions for you and give you references. For starters, visit my website. Cheers

“Jim after several hours of critical listening I have reached a couple of conclusions. First ,everything sounds better and clearer. Secondly there is no down side to this improvement. What I had been hearing as "texture" in instruments and vocals was apparently distortion plain and simple. A friend likened the phenomenon to cleaning a windscreen that you didn't realise was dirty anyway. Not the most original of metaphors but apt enough. And yes the soundstaging is huge. I won't be sending these back but rather may be ordering some more. You see I have some other speakers. Thank you for your ingenuity.” C Cheycox, NSW

The quotation marks are his, not mine, and I think what he means by texture is what we yanks refer to as grain. I can assure you that his texture and tone are improved not to mention how instruments and vocals appear in space (blimey, if I didn't mention it anyway).

[jandl100]

Russ Andrews markets felt rings to go around tweeters - same principle in part as has been mentioned here, I guess - cost a tenner or so, IIRC. The concept seemed interesting so I bought a pair to have a go. Truly, absolutely awful! "Where'd the treble go?" was my basic reaction.

I've had so many speakers I can't recall which ones I had at the time ... Kharmas, maybe .... but the carefully engineered frequency balance of the speaker went straight out of the window. Dull Dull Dull. I sold the pesky things on eBay though

[Marco]

I don't doubt your observations, Jerry, but that's not necessarily representative of what Jim's product will offer. Indeed if Rob's account of them (he's purchased some) is anything to go by then I doubt the results obtained are anything like the same

I may look at trying some with the Spendors when I'm finished with my valve power amp shenanigans. Right now, however, I don't want to introduce any further variables into the equation.

Marco.

[jandl100]

Hmmm ... you have to try these things, I know. But applying a frequency-dependent sound absorber to an already well-engineered product just doesn't seem sensible - surely it can only make it worse by changing the frequency response, or the speaker wasn't well-engineered in the first place! Sorry if I'm seeming a bit negative here, but the idea seems flawed to me.

This observation only applies to the felt pad around the tweeter, I've no idea what the box-surround 'shroud' thing would do - but I do recall a short article in a hifi mag a few years back (by Paul Messenger ... ?) about a similar (or perhaps the same) product and he was full of praise for the improvements he heard, but doubted that most folks would want to change the appearance of their speakers so much.

[NRG]

Russ Andrews markets felt rings to go around tweeters - same principle in part as has been mentioned here, I guess - cost a tenner or so, IIRC. The concept seemed interesting so I bought a pair to have a go. Truly, absolutely awful! "Where'd the treble go?" was my basic reaction.

I've had so many speakers I can't recall which ones I had at the time ... Kharmas, maybe .... but the carefully engineered frequency balance of the speaker went straight out of the window. Dull Dull Dull. I sold the pesky things on eBay though

Exactly the same findings as me, post #6 here:

http://theartofsound.net/forum/showthread.php?t=322

[jandl100]

Yup, I hadn't seen that post NRG. We've obviously had similar experience with those RA felt rings.

Clearly, though, Rob likes what the (non-RA) pad thingy does. I'd be interested in knowing if there's a synergy between the pad and the shroud - did you try them independently, Rob, or just as a combo? Did you find they affected the tonal response?

I hate to be cynical , but have you tried taking them off again to see what happens?