Jay Mitchell's Speaker Directivity Mod

[sosomething]

I just ordered my foam.

I first read about Jay Mitchell's speaker-directivity research and "fix" about a year ago on TGP. (Thread here.) For those who don't want to sift through a massive TGP thread, Jay has reposted the info on his personal website.

I was fascinated by the idea of making my amp sound the same regardless of where my ear was in the room in relation to the speakers. I've always been someone who found the beamyness of closed-back speaker enclosures distasteful, and it bothered me that the tone I liked (standing above or to the side of my cabinet) was not the "true sound" coming out of the speaker or being seen by any close-mic'd applications. I've read about the Weber Beam-Blockers and Egnater "Speaker Bra" but those designs have some inherent flaws (which Jay explains in exacting, meticulous detail) which Jay's method addresses.

When I read Jay's article, I vowed to give it a try one day, saved the link, and forgot about it. A recent thread here on SDUGF reminded me of it, and I've decided to go through with it and see how it works.

I don't think I'll have the time or inclination to post detailed comparison clips (this mod has more practicality in a live situation vs. a recording one anyway) but I'll try to snap some pics & post my findings for you curious folks who may decide to take on this endeavor yourselves.

 

[glassman]

Re: Jay Mitchell's Speaker Directivity Mod

That makes total sense to me...and it's inexpensive...and it's reversable. Sounds like a win-win.

I've had a few harp amps in the shop over the years that had felt in front of the speaker(s) with an off center hole for mic placement. Same concept; different material.

Have fun experimenting!

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

Interesting but I don't buy into the idea of it "not changing" the off-axis response as well. It may even things out but sticking a piece of 1/2 or 3/4 foam in front of a speaker is going to change the sound that comes into the room. Obviously its letting less highs pass, so if there's less in the room 'on axis' then there's going to be less 'off axis' as well!

The frequency response graphs he posted even show that there's a wildly different response at all frequencies with the foam in place. Either on or off axis.

Looking at them closely, or not even that closely... there's a fairly significant difference between things even at 200-300Hz where he said the foam should have basically no effect. If the foam has "no effect" then why is there a difference of almost 5dB on average at 250Hz between foam & no foam?

Examining the other end of it, at 6kHz and above with foam the dB has fallen off the charts... without foam, there's still information going out to 20kHz.

I'm interested to hear what your results will be but of the options & ideas I've ever heard to combat the "beaming" of a closed back cabinet, sticking foam in front of the speakers has never come up.

And then what happens when you want to mic up the cab? Its hearing the speaker through foam, or direct from the dust cap? Eck.

A piece of gaffers tape is as close to acoustically transparent as you'll ever get... the idea of reflecting sound back into the speaker & re-reflecting is fairly implausible.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

I hear you Moose, but the guy seems pretty well-versed in this stuff - enough so that he learnt' a few smart dudes (including Bruce Egnater) a thing or two in that TGP thread and I'm inclined to defer to his expertise.

FWIW I don't hear a lot of useful information in my tones going much above 6khz and usually low-pass that stuff for the most part anyway.

I'm also toying with the notion of leaving one of the speakers in my 6x12 cab uncovered as a "control" for my experiment anyway.

 

[Pink Unicorn Horsey]

Re: Jay Mitchell's Speaker Directivity Mod

Great! Now I have foam GAS.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

I'm not saying that the guy doesn't know what he's talking about... he's obviously has a handle on acoustic principles.

What I'm saying is that really, I don't see this as any sort of "practical" solution for real world conditions. The "real world" being situations where a mic is placed on the amp, be it for recording or gigs.

I just poked through the first couple pages of that 45 page thread & saw where Jay says that yes indeed, he only cares about the "far field" response from 6 feet out or more.

So the foam will work for anyone who plays casually and never leaves their house... which is probably the majority of TGP members.

Open cell foam (commonly used for acoustic control) in a 1" thickness will absorb down to 500Hz pretty well and even down to 100Hz, though it doesn't do much of anything there.

A typical "gained up" guitar sound has quite a bit of information above 6kHz. Stick a mic on your amp, even a 57 and muck around with a good EQ. Twist it up to 15kHz and see what happens when you cut or boost. Stick a low pass filter in at 6kHz and then remove it.

Will it make a difference? You bet!

The only time it might not yield a difference is with 'sludge' tones... someone using a Muff through a bass amp. But with a typical Marshall/Vox/Boogie there's plenty of information at 6kHz & above.

The top end is what makes a guitar breathe. The response around 1-3k is critical...

I never like standing off to the side of my cabs... the amp gets EQ'd while I'm standing directly in front of it. That's the easiest way to deal with "the problem" of uneven sounds as the foam will do nothing for the natural acoustic response of the rest of the room.

Really, its a solution in search of a problem... or a band-aid for something that needs to be corrected elsewhere.

Never once has any player, engineer or producer I've know ever said; "You know what we need? We need to put a pillow over the speakers!"

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

I'm also toying with the notion of leaving one of the speakers in my 6x12 cab uncovered as a "control" for my experiment anyway.

I'd assume that in order to have any sort of quantifiable result you'd have to go all-in and cover all the speakers.

Regardless you could easily approximate the effect of the foam by using a fleece blanket or flannel shirt. Maybe tape it in place & leave a small piece of the speaker uncovered...

But really... if you have a 'problem' with directionality of the cabinet and on vs. off axis response, then going bigger with a 6x12 cab made things worse. Not better. Going smaller, with a 2x12 cab would help things... though its not nearly as 'brutal' eh?

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

I'd assume that in order to have any sort of quantifiable result you'd have to go all-in and cover all the speakers.

Regardless you could easily approximate the effect of the foam by using a fleece blanket or flannel shirt. Maybe tape it in place & leave a small piece of the speaker uncovered...

But really... if you have a 'problem' with directionality of the cabinet and on vs. off axis response, then going bigger with a 6x12 cab made things worse. Not better. Going smaller, with a 2x12 cab would help things... though its not nearly as 'brutal' eh?

Why do you assume I got a 6x12 cab as a reaction to my feelings about directivity?

It's all about tone, man.

(And awesomeness, of course)

Besides, if you'd read Jay's article / posts you'd realize that a flannel shirt or blanket will in no way approximate the frequency-attenuating properties of open-celled acoustical foam.

Also, it would look like sh1t.

And a guy does not purchase a bright orange 6x12 cabinet because he DOESN'T care about the superficial visual impact of a thing like that.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

Also note that (and this has been established previously as well) your "real world" situations only reflect the real world inasmuch as it's YOUR world; a world which is (for better or worse) a lot less real to the likes of me (at least at the moment).

It is not wholly uncommon for me to perform without the luxury of a microphone or monitors. At that point, the backline = FOH and directivity is pretty relevant.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

Also, completely to the heart of the issue:

I prefer the sound of my cabs from the side, or at an angle, but mostly anywhere besides right fuking in front of it.

The foam should make it sound the way I prefer it to sound from EVERY ANGLE.

This can only be good.

 

[xxxplorer]

Re: Jay Mitchell's Speaker Directivity Mod

Can't wait to see what ya get... I wanted to try it too, but my cab would look goofy lol!

 

[GuitarDoc]

Re: Jay Mitchell's Speaker Directivity Mod

Adam,
I'm really interested to hear how it turns out with the foam.

I have to say that I have Weber Beam Blockers on all my spkrs and I haven't noticed any of the negative effects mentioned in the "foam research". What I do notice is that there is no spikey treble beam directly in front of the spkr. All of the highs are evenly dispersed. Smooth and even. Easy on the ears. I hear what the audience hears.

I'm worried that the foam will absorb the highs and take them out of the sound.

Let us know what you find out. I'm very interested in the practical results.

 

[glassman]

Re: Jay Mitchell's Speaker Directivity Mod

I've had a few harp amps in the shop over the years that had felt in front of the speaker(s) with an off center hole for mic placement. Same concept; different material.

I'm quoting myself here. I've actually heard these guys live with this setup. The sound from the stage has subdued highs but the sound from the PA does not. Accoustical foam with the hole offset for mic placement may work as well.

Then again, maybe I've made it to a lot of peoples ignore list...I don't know.

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

Why do you assume I got a 6x12 cab as a reaction to my feelings about directivity?

It's all about tone, man.

(And awesomeness, of course)

Besides, if you'd read Jay's article / posts you'd realize that a flannel shirt or blanket will in no way approximate the frequency-attenuating properties of open-celled acoustical foam.

I did read the article & a number of posts on TGP...

Back in the day and even now, its common practice to put a piece of material over the tweeters on Yamaha NS10 monitors (among others) to subdue the top end and make it less directional. All sorts of materials are used like 1/4 and 1/2" foam... cotton cloth (like an old T-shirt), even regular old tissues or TP.

The idea isn't the material but the effects of the material... and for a quick trial with a 4x12 cab, an old blanket should do fine.

You said you're 'bothered by the beamyness of closed back cabs and that the tone you like (standing to the side) isn't the true sound of the amp' yes?

I'm going to humbly state that if you don't like the sound of your amp while standing in front of the cab, then you should really try to figure out what it is you don't like about the sound and do something to correct it.

It stands to reason that if you don't enjoy the sound of your amp standing directly in front of it, then how can you expect anyone to enjoy the sound?

Its also basic physics that if a closed-back cab is too directional then adding more speakers to the design isn't going to improve things. Actually it'd sorta be like trying to drive a Ferrari with the parking brake on, because otherwise its "too fast" for local roads. You know, there's a better solution then that!!!

As for "real world" my world isn't all quad amped PA rigs with a dozen monitor mixes. Couple weeks ago I played a benefit gig for a hundred odd people and the only thing in the PA were vocals & acoustic instruments.

That's pretty "real world"

Unless you live in Imaginationland then no matter the size of the gig, the relationship between stage volume and FOH is fairly constant. Doesn't much matter if the gig is 50 people, 500 or 5,000.

All that said I am interested to see what your results are...

I'm just not buying that a piece of 1/2 foam has no effect on frequencies under 1kHz, because I know it does and his charts prove it.

Frankly the whole thing smells like something cooked up by a propellerhead who designs PA speakers and has never played in a rock & roll band... or spent time mixing one.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

look

it's worth the

forty dollars

to me to find out if this guy is right; that open-cell foam of that thickness and density does a good job of attenuating the frequencies that are inherently "beamy" in a closed-back cab.

These are the things that don't matter:

how big my cab is. I have observed this phenomenon in every closed-back cab I've ever used (and so have you)
​

why I bought my 6x12
​

who lives in the real world and who lives in imagination****ingland

​

What's amazing to me is, given how you've turned this thread from me talking about trying this method into having to defend it, why I'm doing it, and the equipment I use, that you think I'm gonna share ANYTHING with you about it when it's all said and done.

You already know everything - what do you need ME for??

 

[J Moose]

Re: Jay Mitchell's Speaker Directivity Mod

Woah man.

If you're feeling defensive then that's all in your head... I'm not "attacking" you or anything remotely close to it.

I'm actually curious about the real world practicality of a speaker donut. Its just that I happen to not believe the hype or those charts. You know, looking at them there's a 5dB difference at 200Hz between foam & no foam... so obviously the foam is making a measurable difference.

Will it be an actual 'audible' difference? Beats me.

I don't have 1/2 foam around, nor do I really feel like taking my cabs apart to try it even if I did.

Frankly, like I said... I don't have a problem with my rigs "beaming" since I EQ the amp to sound 'good' when I'm standing in front of it and deal with the ramifications of that when I stand off to the side.

I realize that not everyone does that... but they're usually also the first to ask why their rig doesn't sound the same through a mic as it does in the room.

So, I'm curious to see what your results are... you seem to have a good set of ears & taste.

The 6x12 cab is a whole other thing I guess... to me, that's like someone saying that they hate spicy food, then cooking up a batch of 5-alarm chili.

Since I've never heard your rig all I can do is either assume things or try to understand where your coming from...

If that's offensive, and makes you defensive then there's a larger problem afoot then an overly bright guitar amp.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

Woah man.

If you're feeling defensive then that's all in your head... I'm not "attacking" you or anything remotely close to it.

I'm actually curious about the real world practicality of a speaker donut. Its just that I happen to not believe the hype or those charts. You know, looking at them there's a 5dB difference at 200Hz between foam & no foam... so obviously the foam is making a measurable difference.

Will it be an actual 'audible' difference? Beats me.

I don't have 1/2 foam around, nor do I really feel like taking my cabs apart to try it even if I did.

Frankly, like I said... I don't have a problem with my rigs "beaming" since I EQ the amp to sound 'good' when I'm standing in front of it and deal with the ramifications of that when I stand off to the side.

I realize that not everyone does that... but they're usually also the first to ask why their rig doesn't sound the same through a mic as it does in the room.

So, I'm curious to see what your results are... you seem to have a good set of ears & taste.

The 6x12 cab is a whole other thing I guess... to me, that's like someone saying that they hate spicy food, then cooking up a batch of 5-alarm chili.

Since I've never heard your rig all I can do is either assume things or try to understand where your coming from...

If that's offensive, and makes you defensive then there's a larger problem afoot then an overly bright guitar amp.

well,

see

first of all, it's not like directivity is something that I absolutely hate at all costs. it's something that I have up to now dealt with in mild irritation. it wasn't a motivator in any way in my cabinet choice. that choice was made based on a myriad of other factors; respective of which directivity was an afterthought; one which I am willing to address with the (imo) minimal investment of 40 bucks and an hour's effort.

if it was something that was a big enough deal to me that it would affect my cab choice, I'd probably have commissioned something with a massive flexed baffle, but whatever. like I said - some foam and a little work? yeah - I'm game. Especially since the guy in question isn't selling anything - he's just an educated dude who did some independent research on something that was already of some interest to me.

Actually, FWIW, I find the 6x12 I currently use to be markedly less "directional" than some 2x12s and even open-backed 1x12 combo amps I have owned. It still exists though. but I digress.

Second, the cab-sounds-different-through-a-mic thing you rightly mention mostly becomes moot the second you start working with off-axis mic'ing techniques (in a no-foam scenario). I'm not as concerned about the microphone aspect for two reasons. 1- I generally prefer off-axis sounds anyway, and if there is a big enough treble loss from the foam that I can no longer employ this method, I'll resort to on-axis mic'ing which might make up the difference. if THAT fails, well, it's a 6x12 right? I could leave the bottom-left speaker un-foamed for mic placements and still see plenty of "benefit" from foaming the remaining 5 speakers.

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...

 

[crguti]

Re: Jay Mitchell's Speaker Directivity Mod

too much bla, bla. Result people. Did it work or not?

 

[JOLLY]

Re: Jay Mitchell's Speaker Directivity Mod

too much bla, bla. Result people. Did it work or not?

He just ordered the foam. I don't think it's even arrived to him yet.

 

[sosomething]

Re: Jay Mitchell's Speaker Directivity Mod

He just ordered the foam. I don't think it's even arrived to him yet.

Yeah, I ordered it yesterday.

Adam,
I'm really interested to hear how it turns out with the foam.

I have to say that I have Weber Beam Blockers on all my spkrs and I haven't noticed any of the negative effects mentioned in the "foam research". What I do notice is that there is no spikey treble beam directly in front of the spkr. All of the highs are evenly dispersed. Smooth and even. Easy on the ears. I hear what the audience hears.

I'm worried that the foam will absorb the highs and take them out of the sound.

Let us know what you find out. I'm very interested in the practical results.

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'm quoting myself here. I've actually heard these guys live with this setup. The sound from the stage has subdued highs but the sound from the PA does not. Accoustical foam with the hole offset for mic placement may work as well.

Then again, maybe I've made it to a lot of peoples ignore list...I don't know.

Not on my list!

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.

So

We're gonna introduce rubber to road.

I'll keep ya posted.