[Tyson]

I'm a V2 builder and I tried a tweak today that considerably improved my enjoyment of the V2's, and it's something that's applicable to anyone that uses the P Audio Coax drivers.  In a word: reticulated foam.

OK, that's actually 2 words   A bit of background first.  I "love" my V2's, they solve so many issues I have with my difficult room and are so amazingly coherent and pleasant to listen to, I am truly happy with them.  But, being the person that I am, I always look to try to improve things in any system I'm using.  Toward that end, I'd recently installed some Sonicap Platinums and Gen II's in my crossovers, and the improvement in clarity and overall smoothness throughout the frequency range was impressive.

BUT, there was a very small area that did not improve, it stayed the same.  But it got more prominent/noticable because everything else had gotten better.  Sort of like when the gym teacher asks for a volunteer in gym class and everyone else except you takes a step backwards

The area was what I call high-sibilance.  These are things like brass horns and SSssss sounds from women.  Not to be confused with SSShhhhh sounds, which are what I call mid-sibilance.  The V2's always had a bit of prominence with high-sibilance, but the Sonicap Platinum upgrade in the crossover just left it a bit more exposed than previously.

Trying to understand what I could do to address it, I remembered from removing the tweeters previously that the P-Audio engineers that manufacture the coax drivers Danny uses, had VERY cleverly integrated a waveguide on the tweeter portion of the unit in the center of the midrange driver.  I also stumbled across this thread on diyaudio.com - http://www.diyaudio.com/forums/multi-way/151376-homster-how-i-learned-how-fix-horn.html 

The author there noted a similar issue with dealing with waveguides (and horns in general) as I had, notably a certain hardness at certain frequencies.  Now, I don't have room to build a roundover in the middle of my coax driver, but I certainly have the ability to try the reticulated foam tweak.  Since a good friend of mine, mgalusha has gedlee speakers that use a similar tweek, and those sound spectacularly non-horn like in their smooth and even sound, I figured it would be worth my time to try it.

Any aquarium or fish supply store will have the type of foam needed - a VERY open cell foam called reticulated foam.  I bought several different types, from a half inch thick flat sheet to a big square block of it to do some experimenting.  The easiest to work with, by far, is the half inch sheet. 

What to do:

1. Just cut out a piece of it thats 4 inches by 2 inches. 
2. Roll it up so that it's 2 inches long and 1 inch in diameter.
3. Unscrew your tweeter from the back of your coax unit.
4. Insert the foam, making sure the back of it stays flush with where the tweeter's final resting place is when fully screwed in.
5. Screw back in your tweeter.
6. Turn down your bass by one or 2 db on your amp.
7. If you want a bit more of the effect, cut another strip of foam, pull the original foam out, and roll them BOTH together and re-insert.  They will be a bit more dense now due to the compression, so you'll have to work to get them in, but they will fit if you wiggle and press a bit.

The sibilance should now be gone.  And, if you are like me, you'd likely turned up your bass slightly in order to balance the sound.  You can turn it down a bit and the mids will "pop" even more, and with greater transparency.

Give it a shot, its CHEAP and its EASY.  IMO, it made at least as much improvement as the Sonicap Platinum bypass cap upgrade, which was already pretty darn significant!  I'd love to hear feedback from others trying it out!

Also, I finally got a decent Y-splitter in today for my preamp output so I could run interconnects from the preamp to both my tube amps as well as the sub amps.  For a while, I'd been forced to use the speaker level connectors into the sub amps.  I didn't realize how much the speaker level inputs were degrading the sound of my mids/highs, but after switching to line level, things cleaned up very nicely.  I think I'm done tweaking for a while, just gonna sit back and enjoy some tunes.

[kp93300]

Hi  Tyson,
a picture would be very helpful
Thanks

kp93300

[Tyson]

Hi kp93300,
I don't have any pics but it's pretty easy - unscrew the tweeter, insert the foam, and re-screw in the tweeter.  That's pretty much it!  Like I said, super easy

I have found that in my space the combo of using the 20ohm resistor plus the foam tweek while lowering the subwoofer crossover to 100hz all combine to give really great sound.

[Tyson]

I just got in a pair of Senheisser HD600 headphones, and IMO they are the closest to neutral that Sennheiser ever made (including the latest HD800's), and with the foam tweak, the Platinum Cap upgrade, and the 20ohm resistor, the V2's sound pretty much exactly like the HD600's in my room.  Awesome!

[Pez]

This tweek seems to be prominent in many horn speakers.

And yes that is all I have to add. 

[Tyson]

From a measurement standpoint it changes the FR very little, but from a perceived smoothness standpoint it makes a nice improvement.  From reading the experiences on the page linked above, the better a horn or waveguide is designed, the less of an overall difference in measurement there will be.  But the subjective improvement seems to be significant regardless of the measured difference.

In my own experience so far, it only makes a slight change in overall FR, but a moderately large improvement in overall perceived sound.  I mean, the V2's already sounded pretty darn nice, and the foam just elevates them a bit.

[Guy 13]

From a measurement standpoint it changes the FR very little, but from a perceived smoothness standpoint it makes a nice improvement.  From reading the experiences on the page linked above, the better a horn or waveguide is designed, the less of an overall difference in measurement there will be.  But the subjective improvement seems to be significant regardless of the measured difference.

In my own experience so far, it only makes a slight change in overall FR, but a moderately large improvement in overall perceived sound.  I mean, the V2's already sounded pretty darn nice, and the foam just elevates them a bit.

Hi Danny and Audio Circle members.
If that change or modification mentioned above makes a noticible improvement and difference in the sound, why not make it a standard in your V-2 ?
Guy 13

[PDR]

Thanks for the link Tyler, that was an interesting read.
I get back to home tonite, I will try this tweak......although I dont seem to
have a noticeable sssssss or ssshhhh problem.
I am building a dedicated room here in the next month or so, I am
looking forward to what decent room treatments will do.

One thing I would like to ask, mention, etc.

I realize that the Dr says you need 3 or more subs.....I can see his point about nodes.
I lived with mono, multi subs for about 15 yrs or so. It wasnt till I built this kit....the V-1s
that I realized I was really missing stereo subs.......I have a few Boston acoustics test
CDs .......when they play the Drum kit solo tracks I can hear the lows go from one side to
the other and back again......on other music as well.
Were you mono before the V-2s?........thoughts?

[poseidonsvoice]

Thanks for the link Tyler, that was an interesting read.
I get back to home tonite, I will try this tweak......although I dont seem to
have a noticeable sssssss or ssshhhh problem.
I am building a dedicated room here in the next month or so, I am
looking forward to what decent room treatments will do.

One thing I would like to ask, mention, etc.

I realize that the Dr says you need 3 or more subs.....I can see his point about nodes.
I lived with mono, multi subs for about 15 yrs or so. It wasnt till I built this kit....the V-1s
that I realized I was really missing stereo subs.......I have a few Boston acoustics test
CDs .......when they play the Drum kit solo tracks I can hear the lows go from one side to
the other and back again......on other music as well.
Were you mono before the V-2s?........thoughts?

PDR,

Read this.

Anand.

[Tyson]

PDR, the info that Anand links to is right on.  But with the V1's and V2's the bottom woofers are run upwards into the range of the Schroeder frequency.  In this respect they are more "woofers" than "subwoofers", and will work better in stereo.

I've run small speakers before with a sub (or 2), but never multiples.  I could never localize the sub by sound, but I did feel or sense a difference in where the air pressure was originating from.  I got a similar sense with mgalusha's setup, where he uses 3 distributed around the room, and the bass does seem to come from all around you, but not necessarily from in front of you (although 2 of them are up front).

The other thing is that most audiophile type speakers that use a 7 inch driver for the mids and bass (ie, most 2 way speakers) don't really have enough surface area on the woofers to really deliver believable weight to the frequencies under 300hz or so.  The may "go to 45 hz", but they start to lose authority pretty high up, IMO.  That's why I like the V2's, they have a larger midrange driver to start with, and they transition to the bass woofer higher than you'd normally be able to run a sub.

[poseidonsvoice]

The other thing is that most audiophile type speakers that use a 7 inch driver for the mids and bass (ie, most 2 way speakers) don't really have enough surface area on the woofers to really deliver believable weight to the frequencies under 300hz or so.  The may "go to 45 hz", but they start to lose authority pretty high up, IMO.  That's why I like the V2's, they have a larger midrange driver to start with, and they transition to the bass woofer higher than you'd normally be able to run a sub.

Right on Tyson. Piston area is important too.

Anand.

[tull skull]

I would like to remind you of Jim Smith's experiments reported in his Get Better Sound book.
As I recall he did tests using mono/stereo subs with a recording of a bell choir in a church.
The acoustic signature of the hall disappeared using the mono configuration and I think he said that the effect is most prominent with acoustic recordings.

[PDR]

Thanks for the link.......I have read that before.

As I said, for many yrs I have used more than one sub, I currently have two being used with
my arrays.

I have been a musician since I was 13....long time now, just turned 50. I play almost all woodwinds, bass clarinet
was my choice, but flutes, whistles and such are my favs to play around with.
 
Guitar, mandolin, harmonica.....all in my house, all get used regularly, what I'm trying to say
is that I know what these are suppose to sound like, one of the reasons I enjoy my V-1s so much

So perhaps it is something else I'm experiencing. The drum kit is noticeable moving from one side
to the other, but like you say it maybe that I just perceive it moving with the higher frequency taps,
or it is air pressure.

One of my favourite recordings "An evening with Eric Bibb" is of him and his bass player Dave Bronze.
It is recorded Live, its just Eric and Dave. The bass goes extremely low on a lot of the songs.
Through out the whole concert the bass player is just off center right, about 30 degrees.
Do I just perceive this because of the air being moved in that location?......or what is it?
My tube amp is in for repairs, I have my SS gear upstairs at the moment so my arrays are ampless.
I could drag it downstairs and see if I get the same effect.....bass to the right with my multi sub system.
My arrays are primarily for HT use, thats why I havnt really compared the two before.
Since my V project my primary music listening is with them.
I do have a set of Carver Original Amazings also.....they have 4x12" OB subs per side, could try it on them
also....but they too cross quite high.

So why do I perceive this low bass coming from one point on the sounstage?

Thanks for all the info, Only been in this high end stuff a few years now, I learn a ton from you veterans.

Perry

[ebag4]

Perry,
I hear the same thing from my V1s as well.  It may be cues from something higher in frequency, I don't know,  but I can place low frequencies coming from drums or a bass in the soundstage as well.

Best,
Ed

[HT cOz]

I have been a musician since I was 13....long time now, just turned 50. I play almost all woodwinds, bass clarinet
was my choice, but flutes, whistles and such are my favs to play around with.
 
Guitar, mandolin, harmonica.....all in my house, all get used regularly, what I'm trying to say
is that I know what these are suppose to sound like, one of the reasons I enjoy my V-1s so much

Perry,

That says a lot right there.  All the talk that goes on with people never even listening to a speaker and then people like you have the perfect background to talk about what they have... Classic 

[TRADERXFAN]

Hi Danny and Audio Circle members.
If that change or modification mentioned above makes a noticible improvement and difference in the sound, why not make it a standard in your V-2 ?
Guy 13

The answer to this question is that the use of foam like this was patented by Dr. Geddes:
http://www.diyaudio.com/forums/multi-way/151376-homster-how-i-learned-how-fix-horn-11.html#post2153364

I am sure you could find the patents if you wanted to see for yourself.

-Tony

[jtwrace]

The answer to this question is that the use of foam like this was patented by Dr. Geddes:
http://www.diyaudio.com/forums/multi-way/151376-homster-how-i-learned-how-fix-horn-11.html#post2153364

I am sure you could find the patents if you wanted to see for yourself.

-Tony

This might help:

Patents
 #6,782,112 "An Improved Low Frequency Transducer Enclosure"
 
 #6,269,318 "Method for Determining Transducer Linear Operational
Parameters"
 
 #5,469,510 "Arbitration Scheme for Sound Reproduction System and Active
Noise Control"
 
 #5,455,396 "Temperature Resistant Transducer Suspension"
 
 #5,432,857 "Dual Bandpass Secondary Source"
 
 #5,420,929 "Signal Processor for Sound Imaging"
 
 #5,343,533 "Transducer Flux Optimization"
 
 #5,319,165 "Dual Bandpass Secondary Source"
 
 #5,313,407 "Integrated Active Vibration Cancellation and Diagnostics"
 
 #5,323,466 “Tandem Transducer Magnet Structure”
 
 #5,233,137 “Protective ANC Loudspeaker Membrane"
 
 #5,229,556 “Internal Ported Band Pass Enclosure for Sound Cancellation“
 
 #5,210,805 “Transducer Flux Optimization”
 
 #5,119,902 “Active Muffler Transducer Arrangement”
 
 #5,063,598 “Active Noise Control System With Two Stage Conditioning”
 
 #5,060,271 “Active Muffler with Dynamic Tuning” 
 
 #5,048,470 “Electronically Tuned Intake Manifold”
 

Pending
 "Method for Specifying a Loudspeakers Polar Response"
 
 "A Pulse Width Modulated Controller"
 
 "Acoustic Waveguide for Controlled Sound Radiation"
 
 "Phase Plug With Optimum Aperture Shapes"
 
 "Transducer With Multiple Phase Plugs"
 
 "Compression Driver Phase Plug""
 
 "Refractive Index Waveguide Control"
 

Abandonded
"Transducer Motor with Low Thermal Modulation"
 
 "Method and Apparatus for Measuring Nonlinear Distortion"
 
 "Phase Plug with Low Viscous Distortion"
 

http://gedlee.com/Earl_resume.htm

[corndog71]

Hey Tyson,  are you sure the sibilence isn't coming from upstream componants?