Godzilla said:
Greets!
Different strokes.....
Yes, these 'disappear', and while definitely not the Last Word in resolution, they still sounded far better than I figured they would. Folks with a small room and/or budget could do a lot worse for more money. I'd like to see a well done one from Dave's dwg. perched on a Tony G.? massive 'T' stand, all in Ash/White Oak.Yes, I tested numerous tweaks on the B20 including phase plugs, though not nearly as nicely done as Dave's. Small tapered ones mostly affect the HF so it took a big one to make enough difference in the mids to suit me (huge 500W shop bulb with a crinkly alum. foil cover). The best tweak I tried that transformed it into a real HIFI contender also would increase its cost at least 5x, so no longer an 'el cheapo' nor easy tweak.
It blew up when an amp failed so didn't get to do some other things; so for now, damping the frame/motor, selective damping and stiffening of the diaphragm, doing the $0.98 tweak, and replacing the DC with a large phase plug that pleases your aural sensibilities works for me.
GM
Greets!
My sim peaks around 55 Hz also, though only ~3 dB, so is beneficial rather than distracting. The ~16 dB/octave roll-off will help with room matching too. My way is loosely based on conical horn expansion theory, so I imagine you can figure it out.
Anyway, plug these into the ML-TQWT WS and tell me what you think:
L = 113.38"
SO = 2.036"^2
SL = 265.464"^2
xO = 0.6825 (77.38")
density = 0.2 lbs/ft^3
rp = 3.25"
lp = 1.5"
GM
My sim peaks around 55 Hz also, though only ~3 dB, so is beneficial rather than distracting. The ~16 dB/octave roll-off will help with room matching too. My way is loosely based on conical horn expansion theory, so I imagine you can figure it out.
Anyway, plug these into the ML-TQWT WS and tell me what you think:
L = 113.38"
SO = 2.036"^2
SL = 265.464"^2
xO = 0.6825 (77.38")
density = 0.2 lbs/ft^3
rp = 3.25"
lp = 1.5"
GM
pjanda1 said:
Greets!
A pipe's dominant modes are axial, so tapering automatically makes it stiffer, but it increases its bell modes, so ~the last third of its length needs to be increasingly stiffer. This is also the BW where any obstruction affects its LF output, ergo any additional stiffening needs to be via thicker panels and/or external bracing.
Folding it further stiffens it, so unless the unsupported panel area near/at the mouth gets > ~1 ft square, then 19mm BB ply or similar stiffness is probably sufficient, but if you look at TC's BIB sketch you'll see he added an internal stiffener inside the mouth, so apparently he felt the need for it with the hardwood he used, technically making it a MLTL.........
AFAIK.
Correct, since a tapered pipe has both odd and even modes, the driver's peak is reinforced by the pipe's peaking. Due to the pipe's odd order nulls being closely spaced on either side of it though supresses it somewhat.
If the mouth is extended as a straight pipe, then it will act as a large vent, lowering Fp and changing its modal distribution. This can be a good tweak if done right, so will need to be simmed using the 'sections' WS.
GM
Thanks as always Greg. I'll try those dimensions out in a minute in the ML TQWT sheet. Your own based on conical expansion theory -I think I see what you're driving at. I'm not as up on horns as I should be, but it's time I was, and this looks to be a good opportunity to remedy this apalling lapse!
One thing that's occured to me guys since I've looked at the dims and the scaned picture Andrew emailed: Terry's original box was effectively just the original enclosure, for the FF125K (Fs allegedly 78Hz, if you can believe the Fostex measurements), with the dimensions slightly modified to account for his using 1" wood. That's not a criticism BTW -just an observation that might be pertinent as regards box turning. I would've thought, especially given Greg's comments in an earlier post, that that original box was tuned way too low for the intended FF driver, and Terry's use of the RS 1354, with it's lower Fs would in this respect be the happier match.
Best
Scott
One thing that's occured to me guys since I've looked at the dims and the scaned picture Andrew emailed: Terry's original box was effectively just the original enclosure, for the FF125K (Fs allegedly 78Hz, if you can believe the Fostex measurements), with the dimensions slightly modified to account for his using 1" wood. That's not a criticism BTW -just an observation that might be pertinent as regards box turning. I would've thought, especially given Greg's comments in an earlier post, that that original box was tuned way too low for the intended FF driver, and Terry's use of the RS 1354, with it's lower Fs would in this respect be the happier match.
Best
Scott
Keep it going guys. This has piqued my interest to the
point where I bought some wood.
I just was to going to try one one for the sound effect
of this build using some edge glued 5/8 x 72 in x 12 panels.
This slims down the dimensions and I'd be using something
smaller than an 8". I'd like to lay out in standard 6"
wide stock.
Is this doable? What suggestions for the driver in
sub-hemp or B20 size? Might it be something I have
like the RS 1197?
point where I bought some wood.
I just was to going to try one one for the sound effect
of this build using some edge glued 5/8 x 72 in x 12 panels.
This slims down the dimensions and I'd be using something
smaller than an 8". I'd like to lay out in standard 6"
wide stock.
Is this doable? What suggestions for the driver in
sub-hemp or B20 size? Might it be something I have
like the RS 1197?
Scottmoose said:
Greets!
I posted it quite awhile ago when the B200 first appeared on the forums, but AFAIK, no one built it. I guess since it's not 'T/S flat' enough. FWIW, the cab part of this FR plot is typical of reflex/pipe speakers before T/S and I find it interesting that many folks, especially those of us who grew up with them, find them more 'musical' than current fare, typically referring to them as 'toe tapping'............
T/S specs are nice to have when trying to squeeze the last ounce of performance out of a given bulk or to hit a target alignment, but if size isn't a big deal then these simple designs are hard to beat IMO. Several years ago I did a straight MLTL for the late, lamented RS 40-1354 which has the same general FR plot and really opened some folks eyes at one of the Atlanta DIY Meets with its solid +/- 3dB from ~40 - 12.5 kHz measured response (no BFC or super tweeter since I built them for a hearing impaired friend) filling a fairly large hotel conference room full of people.
GM
I thought that vent size looked familiar. I reckon I'm going to build this -not perfectly 'flat', but nor are rooms for that matter. Nice to use some of the pre T/S proceedures that might be lost otherwise too.
By the way, Greg: how on Earth could the original box (Terry's dimensions effectively) work with the FF125K Fostex used, with a 72Hz Fs? I can't figure that one at all, it's tuned so far below Fs. I ran a couple of inconclusive sims: their cut-off point's are about right according to MathCad, (which astounded me), but the rest seems a little weird. Any thoughts?
Regards
Scott
By the way, Greg: how on Earth could the original box (Terry's dimensions effectively) work with the FF125K Fostex used, with a 72Hz Fs? I can't figure that one at all, it's tuned so far below Fs. I ran a couple of inconclusive sims: their cut-off point's are about right according to MathCad, (which astounded me), but the rest seems a little weird. Any thoughts?
Regards
Scott
Greets!
Not really, I haven't seen any of the Japanese design books or read their various design philosophies, or whether TC even copied the design exactly or not.
That said, historically, the Japanese audiophile apparently covets all things W.E./Altec/RCA/JBL and vinyl/RTR tape sources, so with a low Qts driver their preference has been for an impedance matching amp which effectively doubles Qes and/or has up to 20 ohms of adjustable damping, further increasing the effective Qes, dramatically increasing cab Vb and lowering Fb (Fp) requirements. Now we have a ~critically damped driver in a corner loaded ~IB alignment that has a low amplitude ~one note bass note to fill in down where the source material is at least -24 dB and the amp is rolling off to add a little artificial 'weight' or 'fullness' to the recording.
Works for me since I noticed early on that the bigger the cab I built and the lower I tuned it, the more natural/'live'/'fast' the music sounded and why the only IB I built (~300 ft^3 false wall cavity with four Altec 515Bs) ultimately wound up with long ducted vents.
With today's wide BW, long linear throw sub drivers, digital XO/EQ, and cheap super low output impedance mega power though, it's definitely not the way to go design wise if you want to hear all the music/special effects on some digital recordings.
GM
Not really, I haven't seen any of the Japanese design books or read their various design philosophies, or whether TC even copied the design exactly or not.
That said, historically, the Japanese audiophile apparently covets all things W.E./Altec/RCA/JBL and vinyl/RTR tape sources, so with a low Qts driver their preference has been for an impedance matching amp which effectively doubles Qes and/or has up to 20 ohms of adjustable damping, further increasing the effective Qes, dramatically increasing cab Vb and lowering Fb (Fp) requirements. Now we have a ~critically damped driver in a corner loaded ~IB alignment that has a low amplitude ~one note bass note to fill in down where the source material is at least -24 dB and the amp is rolling off to add a little artificial 'weight' or 'fullness' to the recording.
Works for me since I noticed early on that the bigger the cab I built and the lower I tuned it, the more natural/'live'/'fast' the music sounded and why the only IB I built (~300 ft^3 false wall cavity with four Altec 515Bs) ultimately wound up with long ducted vents.
With today's wide BW, long linear throw sub drivers, digital XO/EQ, and cheap super low output impedance mega power though, it's definitely not the way to go design wise if you want to hear all the music/special effects on some digital recordings.
GM
Re: Personal Preference
Greets!
Thanks for asking! In all my years of 'bench racing' audio on-line, I don't recall ever being asked what my favorite is, though I've periodically mentioned it in passing.
Typically, I listen to AM talk radio on either a '70s el cheapo Lloyd's table radio/phone combo or through what's left of my main rig, which I was forced to sell off much of to support the greedy medical/pharmaceutical/insurance cartels some years ago. Since what's left is for the most part in dire need of maintenance/repair, I don't do any real critical listening.
Anyway, the speakers are corner loaded mildly tweaked Altec 511B CD lens driven with 808 drivers loaded with OEM alum. diaphragms perched on top of 20 ft^3/16 Fb MLTLs loaded with dual Altec 515Bs. XOs are Altec 501-8A 500 Hz/2nd order passive, all EQ'd ~flat in-room using an early dbx digital controller.
I never built my personal favorite, a five way all compression loaded system, settling for ServoDrive Contrabass subs, dual 515B 70-500 Hz midbass/lower mids compression loaded horns, and massively tweaked versions of the 500-20 kHz compression loaded horns listed above.
That said, this being the fullrange driver forum, I don't have a favorite per se since no fullranger can adequately reproduce a wide enough BW with any degree of accuracy except inside the 1 m listening distance due to excessive dynamic compression, so it would have to be at least a two way, and preferably a four way since I'd want the highest eff./resolution wide BW driver available, which I assume would be a tweaked Lowther DX4 or similar.
GM
Greets!
Thanks for asking! In all my years of 'bench racing' audio on-line, I don't recall ever being asked what my favorite is, though I've periodically mentioned it in passing.
Typically, I listen to AM talk radio on either a '70s el cheapo Lloyd's table radio/phone combo or through what's left of my main rig, which I was forced to sell off much of to support the greedy medical/pharmaceutical/insurance cartels some years ago. Since what's left is for the most part in dire need of maintenance/repair, I don't do any real critical listening.
Anyway, the speakers are corner loaded mildly tweaked Altec 511B CD lens driven with 808 drivers loaded with OEM alum. diaphragms perched on top of 20 ft^3/16 Fb MLTLs loaded with dual Altec 515Bs. XOs are Altec 501-8A 500 Hz/2nd order passive, all EQ'd ~flat in-room using an early dbx digital controller.
I never built my personal favorite, a five way all compression loaded system, settling for ServoDrive Contrabass subs, dual 515B 70-500 Hz midbass/lower mids compression loaded horns, and massively tweaked versions of the 500-20 kHz compression loaded horns listed above.
That said, this being the fullrange driver forum, I don't have a favorite per se since no fullranger can adequately reproduce a wide enough BW with any degree of accuracy except inside the 1 m listening distance due to excessive dynamic compression, so it would have to be at least a two way, and preferably a four way since I'd want the highest eff./resolution wide BW driver available, which I assume would be a tweaked Lowther DX4 or similar.
GM
I have the Supravox 165LB, in the box.
The Monacor 5" is supposed to be a really sweet driver, abit "polite" on top, requires abit of power, but a room full of people at a Zu demonstration were amazed at the balance and bass output from such an inexpensive driver in such a small BR cabinet that it largely distracted the crowd from Zu's "Tone" model of standmount speaker ... Sounded like a case of 1 + 1 = 6
Good Luck!!
The Monacor 5" is supposed to be a really sweet driver, abit "polite" on top, requires abit of power, but a room full of people at a Zu demonstration were amazed at the balance and bass output from such an inexpensive driver in such a small BR cabinet that it largely distracted the crowd from Zu's "Tone" model of standmount speaker ... Sounded like a case of 1 + 1 = 6
Good Luck!!
Greets!
Cool!
Same height/depth/driver location, just increase width to ~27.56" (~303"^2), a big step up from the stock 55"^2, so either some external bracing or increased panel thickness will probably be required. If this is unacceptably wide, then the divider board length will need to be adjusted based on the ratio of the width/depth dims you choose. For instance, if a square profile is used, then the divider would be centered at ~17.41"/2 = ~8.7" both horizontally and vertically.
GM
Cool!
Same height/depth/driver location, just increase width to ~27.56" (~303"^2), a big step up from the stock 55"^2, so either some external bracing or increased panel thickness will probably be required. If this is unacceptably wide, then the divider board length will need to be adjusted based on the ratio of the width/depth dims you choose. For instance, if a square profile is used, then the divider would be centered at ~17.41"/2 = ~8.7" both horizontally and vertically.
GM