Yes, to invoke the name of Terry Cain (who also knew his onions), in the case of the Abby design, he used a combination of materials - veneer core plywood for side panels, solid hardwood (Alder?) for front panel and Supra-baffle (Maple and others), and particle board for backs. This was a guy with decades in the commercial millwork trade before "playing" with commercial loudspeakers, and access to wide choice of materials at OEM pricing - in bulk PB and MDF are close to same cost, he chose the PB for its sonics.
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What is commonly available from blue and orange stores:
MDF, PB, OSB. Fir ply, thin HDFB (aka Masonite) small pieces of not too thick 7 ply birch or what we can order from Spruce Aircraft. Then there are things to glue up from the flooring department. Some if it is very dense. Being close to the water I stopped into a chandelry and asked about marine ply. I got prett
I guess I should make up some strips , say 2 inch by 24. Measure their flex and measure their resonance. That should take up a weekend or so. But all that will tell me is the higher the stiffness, the higher the resonance. I was thinking how to hit one consistently enough to measure the CLS. Drop a steel ball from a set distance? None of that helps tell me what I want to use for a typical half foot cabinet. None of it says what the method of exciting it is. Are we worrying about cabinet material when we should be decoupling the driver frame? Does my success with 3/4 MDF come from never having any panel over about 6 x 6 inches due to my bracing? Hat I usually laminate 1/8 hardbard to the baffle back to stiffen it up a tad?
mdf issues
The problem is cultural. MDF is a monoculture, like agribusiness wants the world to work for its shareholders. Selfdamping is nonevident, as with the very rich; richer is gooder! I'll confess that a 1/2 foot mid bass box probably won't reveal the full depravity of this particular panel but your lungs will not cheer the arrival of these fibers and their associated adhesives. My lungs will have no more of it.
The problem is cultural. MDF is a monoculture, like agribusiness wants the world to work for its shareholders. Selfdamping is nonevident, as with the very rich; richer is gooder! I'll confess that a 1/2 foot mid bass box probably won't reveal the full depravity of this particular panel but your lungs will not cheer the arrival of these fibers and their associated adhesives. My lungs will have no more of it.
I don't really like mdf but the cost is very reasonable and great for test boxes. There really are not that many cuts on this box. Also I router and sand outside. I have some 5/8 bb on the rack, pondering what to do with it.
Really enjoying the bass on these compact, easy to build kickers - I do think I lost some of the imaging/spaciousness, although the high end is still charming.
Really enjoying the bass on these compact, easy to build kickers - I do think I lost some of the imaging/spaciousness, although the high end is still charming.
Neither the enclosure alone nor the electronic filters alone are strong enough. With plywood, you have the opportunity to make the baritone crisper and louder or at least more authentic for full range than with MDF. Yet plywood does not remove the opportunity to add any dampening you want.
Plywood is also used in prosound where you want the maximum concentration on dip boosting for efficiency rather than excessive peak cutting and loss of efficiency. With full range, the passive electronic series filters aren't capable of a lot of super selective peak cutting; therefore, I believe that you would like some dip boosting and some plywood. It takes a lot of little steps and we only have little steps available.
The attraction of a full range is "cohesive and lively" and to me that means point source and plywood. With a lively box, I believe that more opportunity exists to add the dampening that you need targeted to more specific frequencies. I also believe that enclosure steps come before arranging the passive electronic filters.
P.S.
Also prior to arranging the passive electronic filters. . .
I'd try the full range along with an amplifier with the drive force (electronic dampening) rather like an asthmatic inflating a balloon since that amplifier could relax the shout and you don't need x-max anyway.
The matching amplifier could be the old tube amp from a Magnavox console. Or if you like, I could sketch something similar sounding using chips ("drive against" sort of bridged) and about $8 parts if you happen to have an older model (at least 9 years old and not pfc) surplus computer power supply available or a regulated SMPS pack (11vdc to 15vdc) that happens to idle warm, not the new style that idles cold.
The deal with the amplifier is that the stronger the drive force the greater the amount of energy used for increasing the peaks of the full range speaker driver. . . and it may be more appreciable to do the opposite.
DAn,
Are you are suggesting that highly resonant boxes made to resonate at where the driver dips? Possible sure. Maybe that gives a pretty plot, but I always work to keep the box from contributing to the sound at all. How much of the breakup resonance of the 225 is causing people to think the driver has more high end than it does? If one tames the 10 dB peak, it does change the balance.
MDF dust is really bad. No doubt about that. I have a dust collector and still use a 100 series mask. I need to get the 5 micron bags for my collector and make movable ports for hand held router and the saw blade guard.
Are you are suggesting that highly resonant boxes made to resonate at where the driver dips? Possible sure. Maybe that gives a pretty plot, but I always work to keep the box from contributing to the sound at all. How much of the breakup resonance of the 225 is causing people to think the driver has more high end than it does? If one tames the 10 dB peak, it does change the balance.
MDF dust is really bad. No doubt about that. I have a dust collector and still use a 100 series mask. I need to get the 5 micron bags for my collector and make movable ports for hand held router and the saw blade guard.
Prized Fender 60's guitar amps were made of 1/2" pine IIRC. (sold my last one a few years back).
The things resonate like crazy, open question whether it added to the sound quality.
But Remove that resonance and current owners would Kill in anger Same applies to their Amps: wayyy out of spec aged Carbon Comp resistors have moved the sound V far away from what Leo Fender pushed out the factory door.
Not even close to original sounds... but the aged sound is prized, cuz that's what everyone 'thinks' it's supposed to be...brain/ear adaptation ain't new 🙂
Also hate the dust of MDF.
Think you guys are barking up the wrong tree on this tho.
In 1" double layers with a resilient glue bonding the 2 layers Box within a box..It makes for a helluva impressive Enclosure.
In fairness I don't know if this is relevant to a teeny speaker/driver... sure is on the 'big' ones though.
The need of back bracing a 4 oz magnet/motor ..seems decidedly odd at first and second glance even. Unfamiliartity on my part or simply Emporer's Clothes?
The things resonate like crazy, open question whether it added to the sound quality.
But Remove that resonance and current owners would Kill in anger Same applies to their Amps: wayyy out of spec aged Carbon Comp resistors have moved the sound V far away from what Leo Fender pushed out the factory door.
Not even close to original sounds... but the aged sound is prized, cuz that's what everyone 'thinks' it's supposed to be...brain/ear adaptation ain't new 🙂
Also hate the dust of MDF.
Think you guys are barking up the wrong tree on this tho.
In 1" double layers with a resilient glue bonding the 2 layers Box within a box..It makes for a helluva impressive Enclosure.
In fairness I don't know if this is relevant to a teeny speaker/driver... sure is on the 'big' ones though.
The need of back bracing a 4 oz magnet/motor ..seems decidedly odd at first and second glance even. Unfamiliartity on my part or simply Emporer's Clothes?
resonance
And then there's the resonances in the driver itself...Delicious when pushed with funky tubeness. These conversations just go on and on. I agree with Dave D who says "everything rings." Quality and quantity. Pick yer poison. Crank it up. What if we enjoyed our lives? Would that be OT?
And then there's the resonances in the driver itself...Delicious when pushed with funky tubeness. These conversations just go on and on. I agree with Dave D who says "everything rings." Quality and quantity. Pick yer poison. Crank it up. What if we enjoyed our lives? Would that be OT?
@ zman01,
A couple of simple tests - shout into the driver hole, listen quickly for echo. There was nothing, nada; very quite and this was before the fill.
Tapped on the woofer once installed, again nothing, no bass sound, etc. (please don't forget I have these piled to the ceiling at this point). However lots of energy when playing.
btw, I did tune with a generator, the curve pieces were "big" and trimmed them down little at a time. The curve pieces were not that even/close, stacked them all up like cards and clamped them in the vice, beltsanded the tops..hehe this worked pretty good.
Starting a new MDF W pair today, will add dowel under woofer. Painting...ugh I don't enjoy that, so probably not.
Bare, The boxes are pretty good for mdf - solid, not that this is bid deal, but all the joints are glued heavily and clamped for 90 minutes before the next step (flip).
A couple of simple tests - shout into the driver hole, listen quickly for echo. There was nothing, nada; very quite and this was before the fill.
Tapped on the woofer once installed, again nothing, no bass sound, etc. (please don't forget I have these piled to the ceiling at this point). However lots of energy when playing.
btw, I did tune with a generator, the curve pieces were "big" and trimmed them down little at a time. The curve pieces were not that even/close, stacked them all up like cards and clamped them in the vice, beltsanded the tops..hehe this worked pretty good.
Starting a new MDF W pair today, will add dowel under woofer. Painting...ugh I don't enjoy that, so probably not.
Bare, The boxes are pretty good for mdf - solid, not that this is bid deal, but all the joints are glued heavily and clamped for 90 minutes before the next step (flip).
Tuning
I doubled checked the tuning today, a small surprise, this is the first time the first peak was almost equal to the second.
1 peak 40hz @ 5 volts (this is the first time it has gone that high)
2 valley 59hz - 60hz
3 peak at 100hz @ 6 volts
4 200hz and above, 3 volts
I doubled checked the tuning today, a small surprise, this is the first time the first peak was almost equal to the second.
1 peak 40hz @ 5 volts (this is the first time it has gone that high)
2 valley 59hz - 60hz
3 peak at 100hz @ 6 volts
4 200hz and above, 3 volts
Not exactly suggesting "highly resonant" but I am suggesting that a "selectively resonant" plywood box is the classic approach to leveling a full range and likewise it is the main approach to super high efficiency pro sound speaker cabinets. For this to make sense, compare it to an open baffle arrangement. . . except, instead of a room that you can't control easily, you have a box that you can control.
The impression of super clear low bass is because of the baritone harmonics when not absorbed/wasted. That idea works for contemporary sized enclosures; however, here's some links to some other ways to make creatively larger resonant enclosures:
http://www.diyaudio.com/forums/full-range/89831-bib-underwear-nothing-top.html
Bigger Is Better 'BIB' Cabinet Dimensions - ZillaSpeak.com
Those two, basically one voight quarter wave feeding another voight quarter wave, back to back, have the same stuffing/padding options as any other transmission line speaker. But, there is yet another example of not padding/wasting/absorbing desired frequencies.
It seems that a lot of the fun of a full range driver is the specially tuned cabinet. It appears to be a slightly different way of thinking opposed to a carpet lined thick MDF enclosure that would absorb as much as possible.
yikes!
Added the BSC as discussed...I had no idea they would ever sound this good!
The bass was good before, but now they are really rocking!!
Starting to sound like a bigger woofer or small sub somewhere.
I did have increase the volume a tad, which is understandable.
Almost forgot...they image better now also.
Added the BSC as discussed...I had no idea they would ever sound this good!
The bass was good before, but now they are really rocking!!
Starting to sound like a bigger woofer or small sub somewhere.
I did have increase the volume a tad, which is understandable.
Almost forgot...they image better now also.
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If I can tame the breakup, we then buypass it on the very top end to get back a bit of the over 10K. There is obviously a limit to what a 4 inch cone can do. A dozen of them opens further possibilities, as well as difficulties.
Daniel won't like BSC wasting all that power. 🙂
I can see in a PA where 3 dB may be 50KW and frequency response is more important than imaging and distortion. Different problem space, different solutions. For now, I'll hold out that anything that comes off the box, inside or out, is distortion.
Daniel won't like BSC wasting all that power. 🙂
I can see in a PA where 3 dB may be 50KW and frequency response is more important than imaging and distortion. Different problem space, different solutions. For now, I'll hold out that anything that comes off the box, inside or out, is distortion.
That was probably appropriate if you've got a solid state amp. Passing the majority of the audio band through that resistor has simulated the loss effect of a tube amp's output transformer, meanwhile the inductor assures you didn't lose any bass. Since the frequency response tilted a bit, if you'd like your airy treble, it looks like a good time to try a variety of really small value polyester cap (or tiny RC) parallel with the inductor. Kudos
I wonder how plywood enclosure tuning sport is different than a horn opening or port tube. And, I wonder about a mixed materials enclosure? It seems that whatever panel of a plywood box that had to be well damped, could be exchanged for MDF?
I like what a BSC can do for single driver and 2-way speakers (in the majority but not all cases). The circuit is more of a shout buster than a bass booster. So, there's less screech, less midrange congestion, more bass, and I'm in favor of that. I have bought BSC parts with great big inductor and nearly insignificant value resistor, which looks financially wasteful, but, to me the "uncongest" function can be well worth the price of the parts. I do like the heavier gauge inductors.
P.S. I found this a good briefing on bass harmonics: HeadWize - Project: The Psychoacoustic Bass Enhancer by Jan Meier The point of mentioning it is that if the room doesn't measure out huge enough to support a 50hz bass fundamental there is still several methods to get some low bass regardless of room size. Modern DSP versions are in FM radio stations, alloy woofers can be rigged to do something similar, a trick analog audio amp could do a slight amount of that, and then there's Tannoy's horn enclosure that is made out of. . .
I guess you describe what BSC does a bit differently that I would. It is a shelving equalizer with pole-zero set to overlap the range where the baffle width causes the shift in 2 pi vs 4 pi radiation. This nothing to do with any "loss effect" of a tube amp.
The small poly bypass is exactly the direction AFTER we deal with the horrendous breakup peak. Doing it now would only make it worse. Step by step. Doug's hard work on the boxes is paying dividends, I need to match it on the driver side.
The small poly bypass is exactly the direction AFTER we deal with the horrendous breakup peak. Doing it now would only make it worse. Step by step. Doug's hard work on the boxes is paying dividends, I need to match it on the driver side.
yes only transistor amp; haven't tried a vintage Luxman yet, supposedly tube like sound.
Couple of questions:
Should I try a better grade 7ohm resistor? (using cement type)
Small cap, how small is small, 2.2, 3.3?
I may build a pair with good grade BB, checking stock wood stock.
Hard work? If I can't work on them, more like signs of withdraw :-/
Couple of questions:
Should I try a better grade 7ohm resistor? (using cement type)
Small cap, how small is small, 2.2, 3.3?
I may build a pair with good grade BB, checking stock wood stock.
Hard work? If I can't work on them, more like signs of withdraw :-/
You could use a stack of metal film resistors in parallel, or some people like Mills resistors and there are other options in addition to that.
Forgot to say my favourite is a stack of Vishay CPF 3 in parallel
Forgot to say my favourite is a stack of Vishay CPF 3 in parallel
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Resistor = loss. If the speaker driver is a classic design originally made for current drive, the BSC's resistor can provide the needed adaptation.
A little bit of loss can also be provided by a bridge amp <--schematic You can use a 3a or better schottky series to the V+ of each board for greater stereo separation if you like. Yes, that amp looks too cheap to be worth anything, but it does show off how a bridge (single rail "bridge against") amplifier can promote a large size soundfield even if used monophonic, and that is worth something. There's a lack of expensive parts, a lack of efficiency a lack of price and a total lack of posh appearance. But if you wanted something tubey, clear and big sounding, that it can do. If one wanted something more complex looking, perhaps an NTP discrete amp would be fun?
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