Ok, self damping... so uncoated (ply)wood might be similar. I had thought about lacquering or painting the cardboard to see what change that made.. aluminum foil would certainly be a shorter path to that. Your overseas friend simply lined the dustcap on those FR drivers with foil and it was a night/day difference? Interesting for sure... More on that in a minute.
RE: material, the cardboard can't be a permanent solution as its resistance to toddlers and flying toys is less than impressive... having rebuilt it once already in the 2 days it's been up there, haha.
I was under the impression that the larger JBL lenses were aluminum, and the smaller ones just plastic. Neither of which would have much if any damping... so I had assumed this was a non-issue?
It's also a different application of course, since all the acoustic lenses I saw in my searches were used with horns - not directly with cone drivers. So there may be some differences there.
Trying random scalloped shapes sounds interesting - or do you just mean different angles? I don't have a way of measuring the distribution or making a polar graph, so it's just by ear - and just needs to be "good enough". The angle of the cutout seems to correlate well with the observed (heard) dispersion response, ie a 60 deg cut makes a 60 deg horizontal fan of sound. I was going for the minimum dispersion that would sit my listening area (couch), and the 60 deg more than covers it, so no reason to go wider or narrower. Different shape to the cutout might change the distribution/intensity, but since I don't have any way to measure it so as long as it sounds good to me, I'm happy!
One thing I might try with a stronger material, like the aluminum sheet, would be to have the cutout go to a point at the center instead of a radius (or just a smaller radius), as there is still a point of higher intensity at the center that isn't being spread enough.
The whizzer in the Fane is a double whizzer - it seems that the mid-highs come from the larger whizzer (it's big, maybe 5-6" across), and the highs from the smaller whizzer in the center (maybe 2" across, and the dustcap about 1.50 across). That smaller whizzer is pretty short, I'll have to measure it but maybe.. 5/8" high? So I'm not sure what's making the highs, the whizzer cone, dustcap, or combination. I suspect the dustcap is an important part of making the HF sounds, so I'm hesitant to cut it off or anything.
I'm essentially treating that dust cap as a compression driver and the whizzer cone as a horn, then spreading it with the acoustic lens... or at least to my way of thinking.
I listened to it all day long yesterday, and didn't notice any fatigue. Though I've never claimed to have golden ears, the slight difference in timing from the lows/mids and highs thru the lens was not noticeable to me. It was loud at times and quiet at times, in between the two most of the time...
Thanks,
Jesse
Sippy, I think the Fane is just a different animal than the 12lta. I wish I had more time to try both, and hear the difference with and without the dustcap on the 12lta. I'm pretty happy with the Fane's sound so far, aside from that 4khz outburst that has to be dealt with one way or another... I did notice that it does not deal well with actually running full range on its own with the volume cranked up - I assume I was starting to hear doppler distortion (correct term?) with the cone trying to make big movement for the bass and still do the HF details.
Jesse
sbcrx,
I dont think that theres that much difference tbh, they both try to do the same thing, have very similar properties and similar short-comings.
One thought that did pop into my head regarding the Fane - the inner most whizzer Might be acting like a phase-plug even though it does have an effect wrt HF production.
I cant say I've noticed 'doppler distortion' with the 12lta though they do start to sound a bit congested when pushed.
My are in P10's EmKen enclosures and barely move even when played loud with bass heavy tracks. EmKen bass is good stuff
I'll keep following, your acoustic lens looks interesting enough to have a go at, I've got 2 off 8x4ft sheets of 3mm ply doing nothing / no use for otherwise.
I dont think that theres that much difference tbh, they both try to do the same thing, have very similar properties and similar short-comings.
One thought that did pop into my head regarding the Fane - the inner most whizzer Might be acting like a phase-plug even though it does have an effect wrt HF production.
I cant say I've noticed 'doppler distortion' with the 12lta though they do start to sound a bit congested when pushed.
My are in P10's EmKen enclosures and barely move even when played loud with bass heavy tracks. EmKen bass is good stuff
I'll keep following, your acoustic lens looks interesting enough to have a go at, I've got 2 off 8x4ft sheets of 3mm ply doing nothing / no use for otherwise.
I have already posted generic templates but will be working on a more universal and usful set. I can always be contacted for the dimensions to use for any specific driver i have done (i have the templates somewhere in my pile), but learning the tap test is very useful.
dave
Sippy - I'm not exactly sure what I'm hearing, doppler distortion was just a guess - it just starts sounding like a mess, congested describes it well I guess. But that's only when used in true full range. I'm currently using them only for 200 hz on up - so the cones never visibly move, even cranked up.
I'd like to hear the 12ltas in those Emkens, I almost went that route... but decided on the Fanes for the extended freq response, and there wasn't an Emken design for them - so I just went simple and built a sealed box q=.707. My 18" slot ported helper woofers supply the bass track
What if I used aluminum for the lens plates, but used a cork self-adhesive veneer? I know I've seen that stuff somewhere in like 1/16" thickness... maybe..
I've got some 1/4 or 5/16 ply laying around too I was thinking of trying - I'd just prefer the aluminum for durability and looks. Childproof acoustic lenses? They probably don't exist... Maybe going the perforated sheet method instead, but that doesn't look nearly as cool! Ha!
Dave, I made a cheesy phase plug for the Fane using similarly high tech materials, and stuffed with cotton to absorb what comes off the dust cap (to simulate it no longer being there), and the results of that extremely rough test (with me just holding it in place over the dustcap and listening from a foot away..) are that some of the highest frequencies go away.. I can only guess that the dustcap then is what makes them? It's pretty stiff.. maybe functioning like a dome tweeter?
Jesse
I'd like to hear the 12ltas in those Emkens, I almost went that route... but decided on the Fanes for the extended freq response, and there wasn't an Emken design for them - so I just went simple and built a sealed box q=.707. My 18" slot ported helper woofers supply the bass track
What if I used aluminum for the lens plates, but used a cork self-adhesive veneer? I know I've seen that stuff somewhere in like 1/16" thickness... maybe..
I've got some 1/4 or 5/16 ply laying around too I was thinking of trying - I'd just prefer the aluminum for durability and looks. Childproof acoustic lenses? They probably don't exist... Maybe going the perforated sheet method instead, but that doesn't look nearly as cool! Ha!
Dave, I made a cheesy phase plug for the Fane using similarly high tech materials, and stuffed with cotton to absorb what comes off the dust cap (to simulate it no longer being there), and the results of that extremely rough test (with me just holding it in place over the dustcap and listening from a foot away..) are that some of the highest frequencies go away.. I can only guess that the dustcap then is what makes them? It's pretty stiff.. maybe functioning like a dome tweeter?
Jesse
yup, distortion.
bass modulating highs, making it sound garbled.
A problem for some of us who occasionally "crank" it, or home theater folks who want our chest hit.
I'm thinking run it with the 18, wide open both, then eq it.
if the sub was more sensitive, you can turn the bass knob down, that would help the fane move less = more volume or less distortion at b4 volume.
Otherwise, onto the evils of crossovers !!!!!!!!! lol.
I'm amazed my 101db 2x15" works well (with bass turned down to zero) with my 90-92db avatar thing when everything run in parallel.
bass modulating highs, making it sound garbled.
A problem for some of us who occasionally "crank" it, or home theater folks who want our chest hit.
I'm thinking run it with the 18, wide open both, then eq it.
if the sub was more sensitive, you can turn the bass knob down, that would help the fane move less = more volume or less distortion at b4 volume.
Otherwise, onto the evils of crossovers !!!!!!!!! lol.
I'm amazed my 101db 2x15" works well (with bass turned down to zero) with my 90-92db avatar thing when everything run in parallel.
Dave, here it is:
SOVEREIGN 12-250TC
I cant seem to link directly to it from the phone, sorry. Fan-ken, eh? It would probably be a similar size to my sealed box, i think it was 3.75 cf.
Re: my cardboard phase plug, right i know its not the real thing, but it did reinforce my thought that I might lose some of the HF sound that was emitted from the dustcap. I can't imagine that little whizzer cone making much sound without the done of the dustcap to back it up - its a very steep cone.
SOVEREIGN 12-250TC
I cant seem to link directly to it from the phone, sorry. Fan-ken, eh? It would probably be a similar size to my sealed box, i think it was 3.75 cf.
Re: my cardboard phase plug, right i know its not the real thing, but it did reinforce my thought that I might lose some of the HF sound that was emitted from the dustcap. I can't imagine that little whizzer cone making much sound without the done of the dustcap to back it up - its a very steep cone.
Norman - Ah that must be what i was trying to recall - modulation distortion. It does take a fair bit of volume to get that garble (with full range signal), and i may have had the bass turned up a bit too. I think i prefer it with the xo in place, at about 200 hz - then the sound is nice and clean.
I didnt care for the sound of the 18 past a few hundred hz, it just started to sound "off"... So I'll keep my xo thank you very much.. maybe having both the woofer and fr both running full range is different though.
Freddy, I'd have to try it again to give a good estimation, but maybe around 1/8" peak to peak where it was pretty noticeable? It comes on gradually so hard to say when exactly it starts...
I didnt care for the sound of the 18 past a few hundred hz, it just started to sound "off"... So I'll keep my xo thank you very much..
maybe having both the woofer and fr both running full range is different though. Freddy, I'd have to try it again to give a good estimation, but maybe around 1/8" peak to peak where it was pretty noticeable? It comes on gradually so hard to say when exactly it starts...
I was being a bit facetious
; of course it's the whizzer! It was no doubt invented to boost/pitch the vocals in a PA's [as in public address] high ambient with little power, so for HIFI it usually needs some serious tweaking and used at no more than its Xmax to keep intermodulation [IMD/Doppler] and amplitude modulation [AMD] low.Sounds like something I'd point out, bell modes galore. FWIW, I de facto knead the starch out of them and if they wind up sounding a bit [too] dull, then either use the cheapest super hold lacquer hairspray or airbrush Dammar or shellac to stiffen them to 'taste' as well as doing what's now known as the Lowther $0.97 tweak. None of mine sound like whizzers.
GM
You're welcome!
No, plywood is much stiffer, so much less damped for a given thickness, so adding tin foil with a thick mastic will damp it back somewhat [constrained layer damping].
No, he covered the entire diaphragm.
Re kids, pets: I always added a full size, very durable speaker grill and in your case the diffuser can be built into it plus by experimenting with materials and one or more layers can go a long way towards toning down a 'shouty' speaker, allowing more durable diffusers; indeed, grills were part of the final tuning process at Altec and presume with the other manufacturers also.
FWIW, the last ones I did for a family with a 'baker's dozen [13] of kids plus two dogs, one cat, pet screen had just come out and having learned the scary way that it's strong enough to hold the weight/withstand the gnawing/clawing of a large, rabid Racoon long enough to get a pistol and shoot him, it became my default recommendation and withstood everything the kids [and dad on occasion] could throw at them. Of course it will need to be tightly stretched and the frame securely attached. Unfortunately, like Ford's Model T it only comes in black AFAIK, but can be spray painted to better blend with the room decor or walls.
The DC is normally glued to the whizzer and it's normally attached to the VC, so the DC is basically just a plug that will be a mass of breakup modes [noise] with an amplitude depending on how rigid it is, so often is best removed and add a phase plug or a felt insert to damp, protect the VC.
I'm only familiar with the original? all aluminum JBL WGs and have seen some steel ones, but don't know/care if they were factory or DIY.
'Scalloped' as in notching the flat plates with one or more patterns similar in concept to JBL's and/or what Freddy posted and considering the difference between the 'rising on axis' of the JBL horns Vs a 'FR' driver's normally multiple mids/HF launch points it may be better overall to use convex shaped plates to ~mirror the diaphragm's concave curve.
GM
Yeah, I'm planning to repurpose the Altecs and don't want to tear apart these fortress built ~20 ft^3 cabs, so planned to load them with 15" AN, but the Fane's a lot cheaper with more Xmax and sims ~112 dB/m/30 Hz/1pi/10 W, so ~115 dB peaks in stereo = 90-100 dB avg. depending on source compression without exceeding Xmax and even more if corner loaded. BIB rules!
This is small electrified venue loud and at 10 W shouldn't have any audible thermal power compression, IM/FM distortion.
Now just got to finish all the property rehab............
GM
If using alu plates I would actually suggest spray-glueing on some sheets of regular printer paper. Maybe get some of those colored papers and glue on the color you like, then you do not have to worry about the inherent properties of any surface finish.
The idea of these diffusor plates is quite interesting, and may fit well with my 15" fane.
What about vertical dispersion?
The idea of these diffusor plates is quite interesting, and may fit well with my 15" fane.
What about vertical dispersion?
Thanks GM, more experimenting to be done! I didn't know you had your Altecs in BIBs, I had somehow assumed they were in Voice of the Theater type boxes for some reason... just my imagination I guess! I'd be curious to hear how the 15's sound. In fact, you guys all need to move down the street from me so I can listen to all these crazy combinations everyone has... I still want to hear a BIB, especially a 12" BBBIB. I suppose a 15" BIB would actually be a B-BB-BIB.
Kaffi and Ivo, I imagine the angle plate lens would work just as well with the 15" Fane, it actually looks like it may share the same whizzer cones as the 12". Keep in mind the plates do also block part of the main cone, so there may be something lost there as well. I had considered windowing the plates outside the whizzer cones, but cardboard isn't the thing to try that with.. aluminum though perhaps. Some days I wish I worked at an aluminum fab shop where I could just go out to the shop floor and say "hey guys, can you make one of these?"
Not sure what effect paper glued to the plates would have, but probably minimal. I think felt might be a better material to try.
I'm actually pretty surprised the cardboard itself doesn't resonate. I expected to get "buzzing" at certain resonant frequencies.
Vertical dispersion, in theory, is same as without the plates. In my (limited) experience, with the plates angled down, there does seem to be more sound down low. So there may be some downward dispersion as well, but it could be something specific to how I have made/attached/stacked my setup, or a result of putting my plates at a full 45 deg, as opposed to less of an angle.
Jesse
I'd be curious to hear how the 15's sound. In fact, you guys all need to move down the street from me so I can listen to all these crazy combinations everyone has... I still want to hear a BIB, especially a 12" BBBIB. I suppose a 15" BIB would actually be a B-BB-BIB. Kaffi and Ivo, I imagine the angle plate lens would work just as well with the 15" Fane, it actually looks like it may share the same whizzer cones as the 12". Keep in mind the plates do also block part of the main cone, so there may be something lost there as well. I had considered windowing the plates outside the whizzer cones, but cardboard isn't the thing to try that with.. aluminum though perhaps. Some days I wish I worked at an aluminum fab shop where I could just go out to the shop floor and say "hey guys, can you make one of these?"
Not sure what effect paper glued to the plates would have, but probably minimal. I think felt might be a better material to try.
I'm actually pretty surprised the cardboard itself doesn't resonate. I expected to get "buzzing" at certain resonant frequencies.
Vertical dispersion, in theory, is same as without the plates. In my (limited) experience, with the plates angled down, there does seem to be more sound down low. So there may be some downward dispersion as well, but it could be something specific to how I have made/attached/stacked my setup, or a result of putting my plates at a full 45 deg, as opposed to less of an angle.
Jesse
You're welcome!
They are in what we now call ML-TQWT or ML-Voigt [ML-V], the BIB reference was because of ~20 ft^3 on a forum where most consider 4 ft^3 a bit much.
If there's no resonances at high power, then they're either 'close enough' or over-damped, so either way you're down to either replicating this with higher resonance material plus finding at least 'by ear' the smoothest overall polar response, highest clarity in the critical phone BW.
GM
They are in what we now call ML-TQWT or ML-Voigt [ML-V], the BIB reference was because of ~20 ft^3 on a forum where most consider 4 ft^3 a bit much.
If there's no resonances at high power, then they're either 'close enough' or over-damped, so either way you're down to either replicating this with higher resonance material plus finding at least 'by ear' the smoothest overall polar response, highest clarity in the critical phone BW.
GM
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