Jay Mitchell's Speaker Directivity Mod

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

Third, as to my defensiveness, you've got to own your communication style in these threads. if I can own mine, you gotta own yours. you know you can be argumentative to the point of frustration. this isn't news to you. there's no putting that all on me, man.

Know that this post is me making an effort. It's actually an edit. I was originally going to just reply with "k." but I decided I'd rather make an attempt to not end this conversation on that kind of note...

Well I appreciate the effort! I'm actually really curious about this stuff... and yeah... the internet is a fairly crappy form of communication. Things don't always come across with the intended intention.

So you find the 6x12 to be "less" directional then some 1x12 open back combos?

Do you run it horizontally or vertically oriented?

I figured out, back in my college days playing with a cover band at this one place that held, maybe 150 if they were all stuffed in there... not much of a PA... that with a 4x12 slant cab I could NEVER really hear myself on the postage stamp of a stage. Meanwhile everyone else (out front) was telling me I'm too loud.

Too loud? I can't hear myself! How can I be too loud?

I'd be right in front of the cab & never heard much of anything...

After a couple rounds of that I pulled out a 2x12 cab that I built in high school, half open back and it was instant relief. Standing it up I was able to hear myself and also not destroy people... I haven't really gigged with a 4x12 since then.

A good 2x12 cab give me everything I need... it'd be nice to have more 'thunk' like a big cab offers once in a while but the 2x12 closed back offers enough & lets me run the amp a little harder.

I've got a sheet of 1" acoustic wedge foam around somewhere... goes from maybe 3/8" to 1" or so. I need to keep my hearing together for the next couple days but at some point I'll be able to blow it out... Jay said it would work just taped over the grille for a quick trial.

Maybe I'll start with an old sheet or a T-shirt. The principle is the same... only affecting frequencies from 1kHz up...

 

[xxxplorer]

Re: Jay Mitchell's Speaker Directivity Mod

I'm interested in seeing what the results bring... and SSS... I wish I had the nads to cary a 6x12 with me everywhere... rock and roll ain't bout da real world baby!

 

[GuitarDoc]

Re: Jay Mitchell's Speaker Directivity Mod

Yeah, I ordered it yesterday.



I have looked at the beam blockers many times, but people have reported that they can create some tonal issues due to their reflecting the beaming frequencies back at the speaker... Of course I've never heard them in person (to my knowledge) so I know that in all practicality, they may work wonderfully. If you're happy with them, that's awesome. Ted Weber definitely knows a thing or two.

I haven't had any such problem with mine either in open or closed back cabs.

Actually, the hole in the foam will be directly in-line with the dust cap of the speaker. I know this seems counter-intuitive to what it seems like we should do, but Jay Mitchell explains that the "beam" is not actually just coming from the dust cap, but the entire speaker. He then goes on to cite a bunch of mathematic acoustical whatsitmabob that goes right over my head.

Actually, if this were true, then Weber's Beam Blockers wouldn't work since they only reflect the sound eminating from the dustcap area of the speaker. All the rest of the spkr should, according to Mitchell, still be sending out very directional high frequencies. But I'm here to tell you that this is not true...Beam Blockers absolutely stop the high spikiness from the spkr.

So

We're gonna introduce rubber to road.

I'll keep ya posted.

For sure. I have an open mind and can't wait to hear about your results. Thanks for being willing to share with us.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

I just spent the last hour or so mucking about the foam donuts on my THD cab which has a removable front panel.

2x12 w/greenbacks... put the closed back on & used my Rivera Rake head.

The foam is 1" auralex 'wedge' foam that goes from about 3/8" to 1" thick.

Since I'm a bit short on time & need to be at the airport around 5:30am I'll offer a one word review for now as it best describes the differences between foam & no foam...


Eeeeeeecccccch.



Radical difference in sound & feel of the amp.

To extrapolate further, it does even out the differences while walking around the room but it also sounds like cock & balls.

Two thumbs down from me.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

I just spent the last hour or so mucking about the foam donuts on my THD cab which has a removable front panel.

2x12 w/greenbacks... put the closed back on & used my Rivera Rake head.

The foam is 1" auralex 'wedge' foam that goes from about 3/8" to 1" thick.

Since I'm a bit short on time & need to be at the airport around 5:30am I'll offer a one word review for now as it best describes the differences between foam & no foam...


Eeeeeeecccccch.



Radical difference in sound & feel of the amp.

To extrapolate further, it does even out the differences while walking around the room but it also sounds like cock & balls.

Two thumbs down from me.

WOW

Your results were WAAAY different than mine.

I just got back from band practice where I put the donuts I made from the low-density foam I ordered from McMaster Carr in my 6x12.

I'm not super-familiar with the Auralex foam, but I assume that since it's designed for sound dampening that the density is much higher than the foam I used.

FWIW, I was getting ready to post that it made only a minimal difference in the sound. The directivity is still there - it might be lessened some but that could just be psychoacoustical... I found myself running the amp a little hotter than usual, with the highs bumped more than I usually do, and the gain dialed back a bit less (probably due to a little extra poweramp involvement from running it hotter) and I was pretty happy with the tone.

I'll give it another week or so to see how I really feel about it. I may end up removing the donuts... jury is still out.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

I'm not super-familiar with the Auralex foam, but I assume that since it's designed for sound dampening that the density is much higher than the foam I used.

FWIW, I was getting ready to post that it made only a minimal difference in the sound. The directivity is still there - it might be lessened some but that could just be psychoacoustical... I found myself running the amp a little hotter than usual, with the highs bumped more than I usually do, and the gain dialed back a bit less (probably due to a little extra poweramp involvement from running it hotter) and I was pretty happy with the tone.

Hmmm... well...

Jay did say to use "acoustic foam" which is what the Auralex stuff is... though to some degree foam is foam. Proper "acoustic" foam has a chemical balance that makes it fire retardant but the ways it affects sound in the upper frequencies aren't radically different from say, art store foam.

FWIW I've never seen "acoustic" foam in anything less then 1" depth...

Anyway!

So if you had to turn the volume up & pump up the highs then its not really a "minimal" difference eh?

Might be worth noting that I started with an amp that makes pleasing sounds to my ear & generally feel needs little "improvement" to make it better. I used the Rivera as a test head since it has two channels with full independent EQ. This all went down with a friend over who, while not really 'golden eared' is fairly acute to things like differences in cables.

With the foam doughnuts in place it killed the tactile response & feel of the amp. I love the sound & feel of my fingers on the string windings and work hard to achieve that sort of response from my gear and the donuts destroyed all of that.

They cut the volume down, killed the top end response and altered the midrange in a rather unpleasing way. No amount of fiddling with the amps EQ's brought things back to a 'pre-foam' state. Sort of like switching new strings for really dead ones along with a good cable for $2 molded end cheese whiz.

It was noticeable enough that when my buddy arrived, with the foam pre-installed and "blind" at first, that he asked what I did to the amp because it sounded radically different... thought there was a bad tube or something.

Between channels there was a greater difference between donut & no donut... while it made an overall difference that was rather large, the differences were less pronounced with clean tones then with the Marshall-ish dirt sounds which were nasty bad with the donuts in place.

I'll say that it does indeed live up to the claim of 'evening out' the sound of the amp as you move around the room... but IMO, it sounds completely dreadful while doing so.

There might not be any "phase" shift from time smear (aka the Hass effect) that comes along with plexiglass barriers, and I hate plexiglass and refuse to foist 'em upon anyone I work with, but I'd MUCH rather have those then the foam. In actuality, the foam/no foam differences DO indeed create a 'smeared' sort of sound even if they aren't doing that specifically.

I guess I can see why some people would like the change but its far from "transparent" or anything close to it. On a different planet really.

FWIW - I sent a link to Jay's page over to one of my hi-fi acoustician friends who works with Focal (hi-end speakers) among other companies and its generally thought that there's some holes in his theory.

As GuitarDoc said... if the speaker is "beaming" from all points on the cone, then why DO the Beam Blockers work?

Anything you stick in front of a driver is going to alter the sound.

Is it pleasing or not? That's up to the user to discern. Personal preference & all that.

 

[Jay Mitchell]

Re: Jay Mitchell's Speaker Directivity Mod

I'm posting here this once to clear up numerous misstatements in this thread. If anyone is truly interested in how and why this idea works, and, just as important, how to correctly implement it so that it will work as designed, I suggest you post any questions you have here: http://thegearpage.net/board/showthread.php?t=470956.

Now, for the first item to be rebutted: the "hole" here is not in my "theory" - more correctly, proven fact that anyone who has actually studied acoustics will immediately recognize - it's in Mr.' Moose's story. There is no way that his unnamed "hi-fi acoustician friend" could have read the page on my site, because it is not there. I took it down some time ago, in anticipation of doing some revisions.

Second, Mr. Moose's statement that "foam is foam," even with the qualifier "to some degree," could only come from someone with no hands-on experience in testing and using materials designed to be acoustically absorbent. There is a huge range of variation among the different formulations and densities of foam, which is why I gave part numbers for interested parties to purchase.

Third, Mr. Moose has latched onto a term - "time smear" - which he proceeds to conveniently misuse in his attempts to "explain" (i.e., discredit) the operation of the modifier. He also misquotes and misrepresents my explanations of the mechanisms at work here. "Haas effect" has nothing to do with anything, nor does "time smear," beyond the effect of a small range of geometrically-varying arrival times on directivity.

It is not true - nor have I once stated or implied - that "beaming comes from all points on the cone." What is true is that sound is radiated from all moving parts of the cone. It is the combination of all the sound from each point on the moving surface that causes directivity. This is neither a particularly difficult concept - it is taught in every Intro to Acoustics course there is - nor is it a controversial one. It is the primary reason that tweeters are always smaller in diameter than woofers.

Next, the modifier will do nothing to address directivity issues caused by multiple drivers in a cab. The individual drivers in a 4x12 have their own directivity - which the modifier addresses - but the array of drivers formed by a 4x12 (or 6x12 or 8x12) has an additional characteristic directivity that will not be affected by any modification you can perform on individual drivers. I explained all this in the TGP thread linked above.

I find it interesting that there are apparently those who feel so threatened by something they obviously do not comprehend that they will resort to flagrant dishonesty and misapplication of the concept in a futile attempt to prove that "it doesn't work." If you ever do want to gain some insights into acoustics, you must first acknowledge those things you do not presently grasp.

I'll add one additional thought. Even though Ted Weber charged a substantial amount of money (relative to the cost of manufacture) for "beam blockers," he never once provided any objective documentation that they do what he claimed. By contrast, I have given away a directivity modifier design that actually works, and I have also gone to the trouble to document that it works - employing lab-grade instrumentation, a quarter century of loudspeaker design experience, a formal education in Physics, and eight years as a full-time working musician. If you try something other than my design - precisely what Mr. Moose has done - and it doesn't work, you have proven nothing beyond establishing your own inability to follow directions.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

If you try something other than my design - precisely what Mr. Moose has done - and it doesn't work, you have proven nothing beyond establishing your own inability to follow directions.

Wow... I'm sort at a loss here... where to begin...

It seems as though every time I asked you a question it was rebutted that I'm a neanderthal who doesn't understand acoustics and has no ability to comprehend basic English and understand "directions" as you say...

I did follow your design... its not exactly rocket science to take some foam & cut a hole in the center.

I also used real "acoustic" foam while I was at it... which, your directions say to use. Sure, at the thickest point its thicker then you said was called for but as its been well established but it was also thinner, and therefore, in my neanderthal world, close enough for rock & roll.

I'm fairly certain you said that really, we're only concerned with frequencies from 1kHz and above. I'm also fairly sure that if we asked any number of A-list acoustics experts such as Chris Pelonis, Francis Manzella, John Storyk or hell, even Ethan Winer (who's more like C list) how effective foam is an acoustic material the answer would be the same...

Not very.

Hence my comparison to a piece of cloth.

Foam is really only effective from 1kHz up, and so are 'acoustic blankets' which are really just U-Haul packing blankets. Heavy towels, T-shirts and other such things generate more or less the same results.

Sort of like using a bookcase as a diffusor rather then a fancy maple or cherry "climbing wall" to deal with reflections.

BTW - Someone PM'd me that exact question on TGP & I haven't responded yet... too busy. I will at some point...

My "unnamed acoustician friend" is Thomas Jouanjean of Northward Acoustics... though I don't really feel the need to name drop on a regular basis, and he (among others) felt your design is snake oil (their words) with theory that's based in textbooks & not so much in real-world application. In other words, there's some discrepancies.

I sent 'em the link to your site on 2/2, a day after it was posted here and it was still up. So that's BS... I suppose you'd like to see his response to "prove" that it happened or something?

My discussions of the Hass effect (time smear) were related to your points on the Weber Beam Blockers which you say 'reflect' sound inward and constantly attack. Frankly I'm not sure why you continually go after Ted Weber either... did he pork your wife or something?

Not everyone needs or cares about scientific proof or 'objective documentation' to prove that something either works or doesn't work as advertised. We're talking about guitarists here... not launching a Space Shuttle.

I honestly went into this with an open mind & unbiased opinions... the caveman guitarist side of me wanted to see if it works (and it does, sorta) but the egghead engineer side of me wanted to explain the theory, and you responded each time, like you did here (signing up to attack me) with a condescending, know it all attitude.

And that's cool man. You do know more then me about speakers... I've never built a speaker.

So I'll just go back to my neanderthal world of no comprehension because I honestly have way better things to do then continue to go around in circles and defend myself.

Peace.

 

[Jay Mitchell]

Re: Jay Mitchell's Speaker Directivity Mod

My discussions of the Hass effect (time smear) were related to your points on the Weber Beam Blockers

Bingo. Haas effect has no relevance to the time scales (<3 milliseconds) in which reflections from "beam blockers" occur.

The precedence effect (often less correctly termed "Haas effect" - note the correct spelling for future reference) occurs from the range of 15-20ms. Once again, it has nothing to do with anything we are discussing. Your apparent failure to recognize that fact can only be taken as a lack of knowledge of the subject.

Not everyone needs or cares about scientific proof or 'objective documentation'

Which is precisely the same as saying, "Don't confuse me with facts, I already know what I believe." Facts matter. If I say an amp that makes 5 watts is a 50 watt amp, is it your position I am telling the truth if I can just find some guys with guitars to say "wow, this thing gets awesomely loud, dude?"

I honestly went into this with an open mind & unbiased opinions...

Your prior posts on this thread make it trivially obvious that this is a false statement. Add to that your challenging, ignorant posts on TGP, and we've got prima facie evidence of trolling on teh interwebz.

If you really had an "open mind," you'd at least go to the trouble to use the correct material to try the idea. Your "experiment" was doomed to fail, and it has nothing whatever to do with whether the modifier works. In order to evaluate a design, you have to actually try the design, not some half-assed misinterpretation of it.

I honestly have way better things to do then continue to go around in circles and defend myself.

Bwahaha. When your initial approach is an ad hominem attack on me - before you have any interaction with me whatever - and you are subsequently shot down, the notion of you "defending yourself" is nothing but a hollow sham.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

Good gravy...

As I said before, I really don't have the energy to put into this thing since my curiosities have been satisfied and its pretty obvious that we're going in circles. Especially if you have to go after my spelling from a typo... geez.

It would be one thing if you were interested in having a conversation, but after I asked a handful of questions on TGP and you came back with "I've already answered that" it became fairly obvious that you didn't want to discuss anything...

So, really... this will be my last response here on the matter. The next post you make as far I'm concerned is for the crickets.

I in fact, did approach this with an open mind. If there's one thing that I've learned in about 20 odd years of slinging music its to be open-minded about anything & everything. Being closed-minded only leads to failure and disappointment.

The basis of my oppositions was purely on the science of the matter, not whether or not the things would actually work. And when I couldn't get a straight answer out of you regarding conflicting data on your site (conveniently removed) and also with what I know of acoustics I went to my colleges who were more then happy to explain things.

And what I gathered, is that there are indeed discrepancies... specifically with regard to frequency origins & the whole mic placement thing. The fact that you refuse to even recognize 'cone cry' & the changes it makes in frequency response as a true artifact of paper coned guitar loudspeakers is enough for me... as cone cry & its effects have been well documented in many places.

You're making an assumption that because the overall transfer function of 'pro audio' speakers is mostly linear, the transfer function of thin paper guitar speakers must be too.

It's exactly the same reason that carrying a 100lb weight across a football field and carrying the same weight across a motocross course are NOT the same experience.

Regardless of the theory involved & the forces at work here... I did try the design with a relevant material and got a result, that dare I say it was not too far off the mark of others experiences.

So if anything was "doomed to fail" as you say, its the donut design in the first place!

On average the foam I used is 5/8" thick, smack in the center of the recommend 1/2 & 3/4 thicknesses. And it was even "acoustic" foam no less! Unless I'm mistaken and Auralex doesn't make acoustic foam... it certainly wouldn't be the first time I used one of their products that made little acoustic effect... hehehe

So as I said, I tried it and it did (pretty much) work as advertised.

With the foam donut in place, there was little to no difference between the on & off axis sound of the amp. Thats the goal right?

However, I'd wager that my experience didn't really differ from SoSomethings in that we both had to turn the volume & treble up to get the tone of the amp back towards where it was without foam.

Did we both fuk it up?

I sorta doubt that we did since we're both fairly intelligent people, and frankly I saw a couple posts on the massive TGP thread where people reported the same changes. Some (though not all) even said that the 3/4 foam killed too much volume & top end.

So really, that'd say that my results were fairly close to the mark. Or at least close enough for rock & roll.

Eh?

If you'd like to make & send me some more donuts (jelly & chocolate glazed please!) I'll be more then happy to try it again, otherwise I'm pretty well done & will go back to my ways of 'X' made with gaffers tape.

Bottom line is that I tried it out, it worked but I didn't like the results and the overall change in the sound of the amp one bit. Whats the big whoop in that?

Frankly I had a nice laugh about it all with one of my buddies at Duncan this afternoon... to loosely quote him... yeah, speaker directionality is a huge problem! That's why Angus Young never moves around on stage... he stands to the side of his cabinets & thinks it sounds terrible... he's gonna stop duck-walking across the stage.

HA!

Cap'n Caveman signing off.