y8s said:
The larger the box, the larger the panels, the more attention needs to be paid to effective bracing. Small boxes need next to none.
Earl is free to use whatever type of brace that he wants, it is his speakers after all.
I have a problem with anyone saying with absolute authority that "this is the best way, period". I think an opinion that is at odds with what the established expert says should be considered constructive. How are improvements made without questioning and rethinking?
Ant, thanks for this, I've been suggesting this at times and got ridiculed... actually I sugessted the poor man's version, using hard wood kitchen spoon or the like. Also a good tool to test how good your isolation from speaker to a wooden floor is (have a colleage knock on the speaker).ShinOBIWAN said:
The Hamaphon stuff is quite pricey but a known "premier choice" for sound proofing in construction.
- Klaus
Cal Weldon said:
Hi Cal,
These are factors in the real world. Here in the fanatical world of audio, these go out the window.
Anyhow, to cut holes in a piece of plywood is not a big deal. It's probably less hassle than the hell you'll get from the missus cuz her broom is missing, unless it's your broom to begin with, of course.
As for locknuts, I've heard that it's good to have more than one if you live in certain areas. By removing the other 4 (or 5 if the hub has six) and violently rocking the vehicle side to side, the remaining studs can be broken off. A tip from a Fast & Furious wannabe. (not me)
Tricky stuff. I've seen some constructions using massive welded steel frames -- but of course the best thing is to avoid direct contact of the driver to the panel... or, for woofers at least, use some antipodal approach with stacked drivers on axis, that is the principle behind ie the Tymphany LAT transducer which can be scaled to be used with discrete drivers. Linkwitz and others (Axel Ridthaler's Ripole) have used that, too.y8s said:
- Klaus
planet10 said:
Hi Dave,
It doesn't need to be pretty to work well.
While the chamfering or rounding over certainly makes it look nicer, it is not strictly necessary. This is not ductwork where air flow turbulence will be a factor. If the rear of the driver is not close to the brace, there shouldn't be air noise problems.
These were cut with 2 sizes of hole saws. The compass is for visual appeal only.
Attachments
planet10 said:
Gees, how cheap do they need to be? http://www.northerntool.com/webapp/...&cm_pla=unproven&cm_ite=mechanics stethoscope
GM
An accelerometer connected to a scope would give a nice visual representation. Use a FG to drive the speaker and pin-point at what frequency each panel is resonating.
Better yet, connect to Speaker Workshop or Arta. Arta will give the CSD for the panels resonance.
BTW, a cheap one to use for this purpose is the MSI ACH-01 - $26.00 from Digikey.
Better yet, connect to Speaker Workshop or Arta. Arta will give the CSD for the panels resonance.
BTW, a cheap one to use for this purpose is the MSI ACH-01 - $26.00 from Digikey.
MJL21193 said:
I've got one, though I never found it to be of much use for my needs. It will show relative levels of resonances in a system, but the attachment method would need to be checked for consistency if comparisons are to be made. I simply used a very small piece of Blu-Tac, but this must add some form of mechanical low-pass filter. I think that Atkinson of Stereophile used some kind of two-sided tape, but I'm still skeptical of repeatable results for comparisons purposes with that method as well. There's not a way to calibrate it for this purpose that I can think of.
It worked well with LAUD when directly connected to the sound card.
Dave
dlr said:
You have a point. How much of a difference between the way it is attached could be checked, and if the difference is small, it could be discounted.
A year ago, I did something similar, but I used a mic at close proximity to measure panels response/output. The idea was to compare the actual acoustic output of each material. Dave considered the result inconclusive though, because they didn't support his view.
Tests start here
MJL21193 said:
You have a point. How much of a difference between the way it is attached could be checked, and if the difference is small, it could be discounted.
A year ago, I did something similar, but I used a mic at close proximity to measure panels response/output. The idea was to compare the actual acoustic output of each material. Dave considered the result inconclusive though, because they didn't support his view.
Tests start here
Nice tests John, I missed those the first time around. Others mentioned that they were inconclusive and error prone but from the methodology such things would have at least been carried across between tests leaving only the relative difference.
I noticed eventually subjectivity was brought in. You can't win against subjectivity, you can say virtually anything you like and your not wrong. Just look at the Enabl stuff. People like magic.
These accelerometer test were done some time ago by a Dutch website:
(if you've got firefox or a later version IE then use tabbed browsing(hold CTRL and click link) to open each and then flick between them for a direct comparison)
18mm Birch Ply
http://www.hsi-luidsprekers.nl/images/kastmaterialen/BmultiZ.gif
An externally hosted image should be here but it was not working when we last tested it.
18mm Maranti Ply
http://www.hsi-luidsprekers.nl/images/kastmaterialen/multiplZ.gif
An externally hosted image should be here but it was not working when we last tested it.
18mm MDF
http://www.hsi-luidsprekers.nl/images/kastmaterialen/MDFz.gif
An externally hosted image should be here but it was not working when we last tested it.
18mm Chipboard
http://www.hsi-luidsprekers.nl/images/kastmaterialen/18spaanZ.gif
An externally hosted image should be here but it was not working when we last tested it.
ShinOBIWAN said:
Hi Ant,
The Dutch tests were presented by Dave earlier in this thread, but he focused on the braced results, not the raw unbraced panel results. Not knowing the exact details of the bracing used, I didn't see the value of those, and went with (as you have done) the raw panel results.
There is some correlation between my amateurish results and these ones. Both show approximately equal resonance frequency for each material, and they both show the plywood to resonate louder than the MDF for the same input energy.
Holes can be picked in every test procedure, especially by those who don't want to accept the results. I did my best (at the time) to make each test consistent.
The reality is that even my tests were hedged - claims are that differences can be detected from listening in a normal position and not with your ear 1/2" from the side of the speaker.
A more realistic test would be with the mic in the listening position. I don't need to wonder what the results of THAT test would show: no difference at all.
But we all know how insensitive these measurement mics are, right?
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