Hammer Dynamics Super 12 looking for cabinet plans

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#4
Hello,
thanks for your help.
I've sent an email to Colleen Wyckoff (yesterday) but at the moment I've no answer.
I've found more info at your link but I don't have the dimensions of the reflex port and the position of the woofer.
Guglielmo
 
#5
You're welcome! These can be scaled off a picture plenty close enough, you just need to use imperial units. If I had MathCad/MJK's software loaded, I could look it up and also post an improved alignment that negated the need for the bubble wrap and Styrofoam 'peanuts'. Maybe we'll get lucky and someone will re-post it.

GM
 
#9
FWIW the vent diameter is 4 inches in the second picture. I'm sitting in front of CAD so it was easy to check.

4" is 10.16 cm in metric BTW.

Driver center is 9" down from the inside edge of the top.
 
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#12
Yeah, panel thickness. Somewhere in that text - if you read the whole thing - it is specified.

John Wyckoff wrote:
>>>There is no port tube in this design. It is tuned to the port being the 3/4" thickness of the baffle. I can recalculate for you if you want to go 1.5" on the baffle.
 
#14
Guglielmo,
Talented designers like GM have hinted about how with today's knowledge and CAD tools it should be possible, based upon the typical Hammer 12" T/S parameters, to construct a superior sounding speaker using an MLTL box alignment. Quater wavelenth box tuning. For the best results and the best diyAudio support you would need to measure the T/S parameters of your 12" speaker.

If your are just as interested in an education in speaker design as you are about building a great Hammer12 Speaker, spend some Google time reading about quarter-wavelength box tuning and Mass Loaded Transmission Lines MLTL. A MLTL cabinet will look similar to the Hammer bass reflex, but the speaker location, stuffing, and port size+location will be calculated to minimize box resonances and maximize deep bass output.

You could still build the original box, but it would be based upon modern knowledge of your options.

Good education at: www.quarter-ave.com
Articles

=========
Got some change?
There are several good tutorials on how to measure T/S parameters. A few coins are often used for a known mass.

Download free sine sweep program + DVM + a couple resistors + small#20-50gram) weight + basic math.

Measuring Loudspeaker Driver Parameters
T-S Parameter Calculator
SB Acoustics :: Technical Notes
 
#15
The Hammer12 cabinet actually is an ML-TL, though it predates MJK coming up with that term. Wyckoff clearly stated the importance of the column shape of the enclosure. There weren't really software design aids in those days. It's true it might be further optimized with one of the modern software tools.

IIRC ML-TL were commonly called column reflex or tower reflex. There were a few Focal based kits around at the time that were pretty popular with the DIY crowd. .
 
#16
Yes, and no, its vent location was high enough combined with its driver location to ~ negate its TL pipe action advantage and why he needed all that damping below it to quell its secondary Eigenmode notch, rendering it more a ~critically damped BR than MLTL, which is my kind of vented alignment, just not the best way IME to get it.

Still, I thought I'd finally found someone on the forums I followed that was at least on the same 'page' as me enough to 'bench race' tower alignments back then, but when I tried to explain about the need for differing offsets to make it more acoustically efficient and do away with all that damping, he dismissed it 'out of hand' as just another 'attack' on his design as we'd already 'crossed swords' on-line WRT which was better: wide range + super-tweeter or my preference that the pioneers had concluded was the best overall compromise, woofer + 'FR' [AKA 'FAST'], but let it go since by then I'd found out how deathly sick he was.

GM
 
#18
As I recall, since like GM it's been a number of years since I last looked at the Hammerdynamics kit, the enclosure was (by my standards at any rate) somewhat undersized in Vb for the driver. That said, I don't think the full details of the modified Hammer driver were ever released, so a little theoretical back-engineering was needed to fake up those parameters that were not stated, so YMMV. If I get a minute, I'll try to dig out an old MJK sim of it -if you want to fire me your modified dimensions Greg, I'll do that one while I'm at it.
 
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#19
I wish I could, but for now all my info is 'hidden' from me until I either learn more about computers and/or pay someone to sort it all out since both my computer gurus are having a much worse time of it health wise than me, so MIA; ditto my budget with the latest round of surgeries, storm damage.

That said, I remember enough of my design routine to 'wing' it for CSA/net Vb, though not the driver location, so we can use either MJK's 0.349 or the 5ths 'rule-of-thumb' 0.4, ditto either 5ths or 7ths for the vent unless your latest MJK software says otherwise.

GM
 
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