Rear Magnet Support for a 515B in a A7 enclosure. QUESTIONS

[bowtie427ss]

oooops, my bad.

I understand seeking all the opinion you can find. But, sound, and good sound are so subjective beyond the individual listener.

My theme here is simply to listen, listen, and listen more. Don't be afraid to experiment.

There are still an entire market segment out there than think a Klipsch Lascala is a hifi speaker on par with the best. i can't think of any way that i would agree with them. But, at the same time, i cannot and would not tell them what they do or don't hear.

There is just a personal element to what "sounds good" and that personal element certainly is not the same thing for everybody.

Also FWIW, OG may not always have the softest bedside manner, but he brings many good things to the table. While i can't and wouldn't speak for him, i don;t think his posts are the personal attack that some folks take them as. Take him with a grain of salt if you have to, he's good stuff and this place would surely miss him.

.................. and yes, i can be an asshat at times too, i freely admit that.

[Old Guy]

I'm not judging. I am saying a random approach and deciding "this works,that doesn't" produces more fallacy than fact.

If you were offended that wasn't the intent, Just seems that one judgement is made one day, as in the braces, and goes out the window the next. The other is what works for someone may not give you the same results. If you didn't do it, you cant decide. And often in audio what doesn't work one time may work another if tiny changes are made.

If you really feel the driver needs support consider a vertical 2x4 from the bottom with a small horizontal at the top, possibly with a rubber pad for shock purposes.

I'm the person who hates wasting time. I do believe in research. If you heard the driver sounds better supported how did those people support it?

[tomt]

Don't know anything , but I like to invent. What is the diameter of the 515 magnet cover which is all that the brace would be supporting?

last time i measured mine i got 6" diameter.

not exactly tho ....


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perhaps something like this -



these come in a variety of sizes,

i forget what they are called .

certainly less airflow restriction

than the more common lumber bracing ....

[LowOhms]

I'm not judging. I am saying a random approach and deciding "this works, that doesn't" produces more fallacy than fact.

If you were offended that wasn't the intent, Just seems that one judgement is made one day, as in the braces, and goes out the window the next. The other is what works for someone may not give you the same results. If you didn't do it, you cant decide. And often in audio what doesn't work one time may work another if tiny changes are made.

If you really feel the driver needs support consider a vertical 2x4 from the bottom with a small horizontal at the top, possibly with a rubber pad for shock purposes.

I'm the person who hates wasting time. I do believe in research. If you heard the driver sounds better supported how did those people support it?

Hi,

You state "Just seems that one judgement is made one day, as in the braces, and goes out the window the next."

Not really at all, no sir. You misinterpreted me. I seldom flip-flop on audio.

My intention remains to make it, as much as possible, a braceless interior A7 by using 24 mm B.B. No glue blocks, all dadoed, screwed and glued. Ninty degree wood transitions will all be epoxy puttied and smoothed with my thumb.

But, when I am told by a movie theatre and hi fi industry professional, who has decades of experience, ( and whose systems I have listened to ) and liked a LOT,

" that a 515B, or a 604 sounds better with an added rear support, and not just mounted by the front frame mounting bolts ",

I take notice.

This is the same person who advised me to build my own A7 out of one inch thick plywood, and NOT to add any interior bracing that interrrupts the internal air flow inside the cabinet.

His suggestion was for a rear 515B brace - using a thin Plumber's Strap. ( I am also considering webbing / strapping material as a "sling". )

Think O.G., how much less of a cross section a thin strap has, verses a two by four below, and another length of wood wedged on top. The difference in size ( to disturb airflow) might be thousands to one.

I am still hoping someone has experimented with rear-of-driver support, ( versus front-of-frame only mounting ), in addition to my audio friend and Siegfried Linkwitz on line. We will see !!

Best wishes and thank you for your input,

LowOhms ..................Jeff Medwin

[mah]

Could the plumber's-strap(under tension) be vibrating and adding a subjectively pleasing 2nd harmonic to the sound??

[mah]

Solid inspiration:

http://www.cooperindustries.com/cont...ts/Hangers.pdf

[Old Guy]

This one looks like it hangs by a threaded rod.....from mah's post

[alancohen]

Could the plumber's-strap(under tension) be vibrating and adding a subjectively pleasing 2nd harmonic to the sound??

I think the proper thing to do would be to incorporate a tensioning device into the strap to be able to tune that 2nd harmonic!

[bowtie427ss]

Improperly tensioned, those devices will quickly and easily pull the motor out of alignment.

The basket's highest ability to support a load, by design, is mass loading from the rear.

My understanding has always been that the "proper" thing to do is to brace to the extent that as much of the driver's acoustic output as possible is radiated as such rather than being sucked up by wiggling the cabinet.

[LowOhms]

Improperly tensioned, those devices will quickly and easily pull the motor out of alignment.

The basket's highest ability to support a load, by design, is mass loading from the rear.

My understanding has always been that the "proper" thing to do is to brace to the extent that as much of the driver's acoustic output as possible is radiated as such rather than being sucked up by wiggling the cabinet.

Hi BowTie,

I agree with your statement when you start it with the words " improperly tensioned ".


I vote to do the execution with words such as this :

" properly, lightly tensioned so as to be supportive "

You also state "The basket's highest ability to support a load, by design, is mass loading from the rear."

Oh really? How did you come to make that conclusion ? I'd think it ain't necessarily so !

I still sorta like my earlier comment about rear loading as acting like a out-of-time negative feedback loop, an acoustic one !! But, thats my viewpoit, may not be correct at all.

One GOOD thing is, if I do this, I can listen to the speaker both ways, and decide for myself. To that idea, I am sure we can both agree.

Regards,

Jeff Medwin

- - - Updated - - -

Solid inspiration:

http://www.cooperindustries.com/cont...ts/Hangers.pdf

mah,


UTTERLY FANTASTIC !!!!! Thank you so much . Now, get out the tape measure and look at the 515B and 604 dimensions and A7 825 blueprint !!!

GREAT JOB mah.


LowOhms.....Jeff Medwin