Is there a DIY technique to measure the BL curve of a woofer?

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#201
@ b_force
You are right regarding "VAKUUM". We are talking about a maximum of 10 to 15 mbar measured pressure or negative pressure.

@Boden
If you're talking about Juergen T.'s solution, then it's certainly excellent, but I guess the price is probably in the region of €10,000-15,000 (just for the hardware).

Regards
Heinrich
 
#202
hurrication said:
That sounds good in theory, but if anyone who does all of these things deviates their designs away from the same ol' thing that Forum Expert™ narrative has dictated for the last 40 years, you will still get told you don't know what you are doing. I've had Experts™ on this forum call my designs "mud pumps" while the design is literally going into production as a high end hifi product, just because it's different than the thing they have known for the last 3 decades.
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Yes you are absolutely right -

Only where cost to quality & cost of quality is a factor then-
To start - and get their business off the shelf and becoming a supplier (if only making the drive unit) or getting end product off the shelves into homes, most likely - Magnet size would not have been re-invented and off the shelf form would have been used (quality like Y28 to Y40 on N30 to N50 being a variable), as soon as the mag size is same - the top & bottom plates can be acquired that conforms to that shape easily from several suppliers. Depending country.

Once there is rolling - and if one had end to end control of the speaker parts - that is they make their own spiders & cones - along with vc & motor structure, - a lot of flexibility in trying new designs is possible.

Hi-End does not have costs to quality as a large limiting factor, with that said, small runs of Neo Mags is possible, thanks to the innovation & ingenuity that all the neo mags are sourced from that small runs of any form factor of neo-mags is available - else one would be yet limited to the 40 year old - 55,90,120,135,160,180 OD cer mags.

By the way - what is your design , did you make all the speaker parts in-house or they were bought from vendors.

Best Regards
Suranjan
 
#203
Kravchenko_Audio said:
The more I thought about it, the more I have to agree. A few coats of polyurethane on the inside and outside you should be fine. Much easier to make a box too! The vacuum will be relatively small.
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Hi Mark - just a thought - cut the panels - dont glue them yet - buy cycle tube - cut into strips. Put these rubber strips between panels - then silicon - and screw.
 
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#205
hunter audio said:
Hi Mark - just a thought - cut the panels - dont glue them yet - buy cycle tube - cut into strips. Put these rubber strips between panels - then silicon - and screw.
Click to expand...
The easiest method to build a very airtight enclosure is to use a polyurethane construction adhesive. Sika is a trans-national company that sells this stuff all over the world. Here in Canada and the USA we have Henkel, and they sell a product called PL Premium. It is a reasonably strong adhesive. It expands upon curing so fills void s between the parts you are assembling. And is slightly pliable, not a rigid cure, so it is tough to tear apart. So enclosure made via the normal methods, glued and sealed and I need to buy a few air pumps. And figure out a little plumbing and wiring.

Before that I have two Driver motor simulations I have promised to make and share. So much to do! So little time to do it!
 
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