Anyone try this fix for speaker beaming?

[muddycreek]

http://www.tgpwebzine.com/?page_id=424

Seems interesting, especially for larger speakers with a rising high end on-axis. Anybody here try it? If it's even remotely useful, it seems like something anybody could do with 20 minutes and 10 bucks.

Jon

[billfitzmaurice]

Originally Posted by muddycreek

If it's even remotely useful, it seems like something anybody could do with 20 minutes and 10 bucks.

Jon

It isn't. It does nothing to widen the off-axis response, it just kills on-axis so that there's less differential between the two. A Weber Beam Blocker is far from perfect as well, but it's better than this. But still the only real cure for beaming is a midrange driver.

[muddycreek]

Really? It seemed to make sense, with the foam sucking up most of the high end from the outside, 'cone' part of the cone, leaving what high end was left coming through the donut hole and diffracting from a smaller space, thus coherently. I'd expect reduction in the top end, creating a muffled sound but with some highs left over, and a wider sweet spot to EQ back in some high end.

Guess there's nothing free. It does make sense, though, that a bunch of guitarists used it and liked it, probably makes the rig sound more uniform all around if you're used to being seriously off-center to begin with.

[JimmyM]

Originally Posted by muddycreek

Really? It seemed to make sense, with the foam sucking up most of the high end from the outside, 'cone' part of the cone, leaving what high end was left coming through the donut hole and diffracting from a smaller space, thus coherently. I'd expect reduction in the top end, creating a muffled sound but with some highs left over, and a wider sweet spot to EQ back in some high end.

then you'd be back at square one with the guitarist drilling everyone with treble. beaming is a function of speaker size and it's still going to beam.

Guess there's nothing free. It does make sense, though, that a bunch of guitarists used it and liked it, probably makes the rig sound more uniform all around if you're used to being seriously off-center to begin with.

that's the conclusion i came to when i asked bill about these things a couple years ago. there really is nothing free.

[1n3]

I have a Kappalite 3015 that I acquired in a barter. I'm considering it for a single-driver cab. A simple device to make radiation more uniform would be good, and this one has had my interest since I saw the link on the fEarful wiki (an ironic source). I know it reduces the difference between on and off axis by reducing HF output. I think I could live with that because I don't like a lot of highs anyway, and it should be easy to compensate with the treble control. Yes?

So... has anyone tried this (or a similar device) on a bass cab?

[rpsands]

There is a simple device for beaming reduction, it's called a crossover and a midrange driver.

[JimmyM]

Originally Posted by 1n3

I have a Kappalite 3015 that I acquired in a barter. I'm considering it for a single-driver cab. A simple device to make radiation more uniform would be good, and this one has had my interest since I saw the link on the fEarful wiki (an ironic source). I know it reduces the difference between on and off axis by reducing HF output. I think I could live with that because I don't like a lot of highs anyway, and it should be easy to compensate with the treble control. Yes?

So... has anyone tried this (or a similar device) on a bass cab?

i once thought about it, but a couple folks pointed out to me that they have never been drilled by too much treble from a bass cab and i didn't pursue it any farther. i think the benefits of not beam blocking the 3015 will greatly outweigh the benefits of beam blocking it, but then again you may love it, and it's not like you'll go broke trying it.

[1n3]

Originally Posted by rpsands

There is a simple device for beaming reduction, it's called a crossover and a midrange driver.

I agree that this is the more effective solution, but I think "simple" is at least debatable.

There are a number of reasons to choose a single driver cab. For that case, does a simple device like this allow you to boost off-axis treble without the on-axis becoming overly bright? If so, I think it has some merit.

[JimmyM]

Originally Posted by 1n3

I agree that this is the more effective solution, but I think "simple" is at least debatable.

There are a number of reasons to choose a single driver cab. For that case, does a simple device like this allow you to boost off-axis treble without the on-axis becoming overly bright? If so, I think it has some merit.

read post 4 again.

btw, i have a couple single driver cabs and i love them, beaming or not.

[1n3]

Jimmy, I re-read post number four. I guess you're referring to "there really is nothing free". I think I have conceded that. The trade I could accept is lower HF output in exchange for better HF dispersion.

Look, this guy (Mitchell) has at least posted measurements, which elevates him above the usual guitar-world voodoo, IMO. I haven't seen anything similar for the Weber blocker, though for me, that was the more intuitive approach.

I get that it's not optimal, but the prevailing opinion so far has been that it's not useful.

As you say, it won't cost much, but I (and the OP) hoped someone who has tried it would weigh in here.

[billfitzmaurice]

Originally Posted by 1n3

Look, this guy (Mitchell) has at least posted measurements, which elevates him above the usual guitar-world voodoo, IMO. I haven't seen anything similar for the Weber blocker,.

If you did you would see some reduction in the on-axis SPL, with a corresponding increase in the off-axis SPL. With careful attention to the size and shape of the blocker significant improvement in the overall result can be obtained. How much time was spent testing the Weber version I can't say, and as you note it's unfortunate that no measured results are available.

[Jazzdogg]

Originally Posted by 1n3

<SNIP> does a simple device like this allow you to boost off-axis treble without the on-axis becoming overly bright? If so, I think it has some merit.

If the "simple device" to which you refer is a suitable midrange driver teamed with an appropriate crossover, it seems highly unlikely that an improvement in off-axis frequency response would somehow make "on-axis [treble] overly bright."

I have three bass cabinets that incorporate mid-range drivers, and all of them provide clear, coherent, midrange while improving off-axis performance in the process; IME, good mid drivers provide better sound quality, more control, and better dispersion than most single driver cabs of the same quality.

[1n3]

Originally Posted by billfitzmaurice

If you did you would see some reduction in the on-axis SPL, with a corresponding increase in the off-axis SPL. With careful attention to the size and shape of the blocker significant improvement in the overall result can be obtained.

Thanks, Bill. That's encouraging; it's what I would expect, though intuition can be wrong. When Mitchell begins with the observation that large cones do not act as simple pistons at high frequencies, his approach also seems plausible. But redirection is a more appealing method than attenuation.

Some of your designs are also the genesis of this interest of mine. Features like throat fillers and diffraction horns got me thinking about ways to improve the HF dispersion of a speaker like the 3015. From the response here, it appears this hasn't been explored much for bass, and I'm not in a position to do it myself right now. A future project...

[billfitzmaurice]

Originally Posted by 1n3

Some of your designs are also the genesis of this interest of mine. Features like throat fillers and diffraction horns got me thinking about ways to improve the HF dispersion of a speaker like the 3015. From the response here, it appears this hasn't been explored much for bass, and I'm not in a position to do it myself right now. A future project...

Since I don't do direct radiators it's not something I've ever tried.

[JimmyM]

Originally Posted by billfitzmaurice

Since I don't do direct radiators it's not something I've ever tried.

why don't you? you've said before you think cabs like the fearful are great. or are horn designs that much superior where direct radiators don't interest you?

[billfitzmaurice]

Originally Posted by JimmyM

or are horn designs that much superior where direct radiators don't interest you?

They are. And if you want to build a direct radiator there are dozens of sources for them. If you want to build a state of the art horn there's me and there's...there's... well, no, there isn't.

[muddycreek]

Originally Posted by JimmyM

why don't you? you've said before you think cabs like the fearful are great. or are horn designs that much superior where direct radiators don't interest you?

Not to put words in Bill's mouth, but he certainly has a niche that's relatively unoccupied otherwise. If he was taking r&d time away from horn designs to do direct radiators, he'd be walking into an already overfull market with very little opportunity to differentiate his products, and losing time and effort on his horn designs in the process.

The fearful designs are probably pretty tough to top, and probably as complicated as a successful DIY venture's needs to be as far as electronics go.

What I'd love to see, just conceptually, is a workable round waveguide around a 10 or 12. Dunno why, just seems like an elegant solution. It's tempting for me to get a kick drum, brace it, and bastardize a Jack design to go in a circle. Just cut and layer 1/8 Lauan for the horn. It'd make a decent coffee table with a piece of glass, if nothing else...

[Codger]

Originally Posted by muddycreek

Anybody here try it?

Yes.

If it's even remotely useful, it seems like something anybody could do with 20 minutes and 10 bucks.

IME it does what it claims to do.

IMO it is best suited for a guitar amp situation. Those guys will never go with a multi-driver/crossover solution and consequently beaming is a problem. They can crank the treble slightly and overcome the attendant loss of highs due to absorption.

[DukeLeJeune]

I've experimented with Jay Mitchell's foam donut, and with a 12" guitar speaker it pretty much eliminates the on-axis icepick at the expense of reducing upper mids and highs at all angles. It makes less of an improvement with a 10" cone, haven't tried it with a 15" cone. It is not worth doing if you have cones side-by-side.

It's probably a useful retrofit in some cases, and if you like the improved pattern uniformity but want more upper mids and highs you'll have to go with a cab that properly addresses the radiation pattern at the design stage, like a Fitzmaurice design or a fEarful-type.

[muddycreek]

Well, I just tried it on a whim with the most low-rent version I could come up with at a moment's notice. I was trying out biamping with my older Marshall head and a small QSC I have lying around, and started thinking about the donut. So, I looked around the space, and came up with an empty drumhead box that fit behind the screen of an old TOA PA speaker I have. I cut a 3" or so hole in the middle.

So, plugged full-range into just the 15" driver, I AB'd for a while with and without the donut.

I know there are several flaws here, principally that my donut was not absorbent (although cardboard/air/cardboard probably attenuated 400-1K or so before it got reflective). However, it was an interesting experiment.

The sound itself was greatly changed, mostly choppier in the midrange, which I attribute a lot to the non-absorbent donut - all those highs and mids had to bounce around in there and come out at some point. However, it still HAD a reasonable amount of highs and mids, and was FAR more uniform out to something like 70 degrees off-axis. It also didn't show nearly any beaminess.

EQ'ing back in a little high and a very small amount of high mid, and dipping out a little 400 brought me back to a similar tone to what I had had before.

Overall, I'm interested to try with something absorbent. I have a feeling that the recommended 1/2-3/4" thickness may not cut it for bass. To absorb, or significantly attenuate, the foam needs to be closing in on a quarter wavelength.

Based on my own paper napkin bumbling, it looks like a 15 is just barely going to start tightening up it's radiation pattern around 400, and get more and more beamy after that. Half an inch of foam is going to leave that 400-1.5K range pretty much as-is.

I'm thinking I'll try something a bit thicker.

Now here's the idea I need you guys to shoot holes in (although I'll do it anyway).

So, in theory, I have this fat foam donut in front of a 15. I'm getting more even response, because most of my mids and high end are radiating from a smaller source (the donut hole). But, I have a problem, because they're not keeping up with the lows, as I'm not using as much of the drivers' surface to produce them.

Why not build a SOLID waveguide INTO the donut, starting around 3", and widening out through the thickness of the foam? It'd look like a whizzy, but not be attached to the speaker cone. Might this increase the high end efficiency of that center few inches of the driver, while retaining the smaller source that keeps it from beaming?

I've got some cardboard, some old couch foam, and an electric turkey knife (anyone who's never cut foam or 703 with one of these guys, try it). I'd love to hear any thoughts you guys have, but I'll report back when (if) I'm able to put the time in. Hopefully tomorrow night...