audio-talk

Stumbled across PureAudioProject the other day. They have some interesting OB speakers for sale, using new versions of the Eminence woofers, optimised for OB use.
They seem quite supportive of the DIY market so you can buy the woofers from them.
http://www.pureaudioproject.com/product ... s-woofers/
They do not seem to be available direct from Eminence....

Yes been looking at those Max. Having talked to Mark though, he reckons Betas are a better bet for OB. Lot cheaper too.

The neo version looks to be somewhere between the Alpha & the Beta in terms of Qts.
Would be interesting to hear them, but I agree they are a bit spendy for a punt.....

Yes indeed, think I'll stick to Betas for the new OB's.

Probably a good choice. You'll lose a bit of LF gain but transient response should be slightly superior with the lower Q of the Betas. YMMV as always of course.

Cheers Scott.

Hi Scott
Do you think that any of the other features of the new woofers are likely to make much difference?

“ These are the higher performance and lower distortion 15” drivers that have been specifically optimized for Open Baffle use. They share the same cone and surround as the Alpha15, but are different in all the rest. With the Neo version we went with Cast basket, stronger neodymium magnets, 2.5” Voice Coil motors to gain more motor strength, increase linearity, increase power handling, lower power compression, and to be able to add shorting rings to lower distortion and lower the Le. To further lower distortion and cut down on basket ringing. With the Neo model we use our rigid cast Aluminum frame, a very open basket for minimum turbulence and push-button terminals and with the ferrite model we increased the thickness of the highly ribbed and windowed basket form 18ga to a much heavier 16ga steel and. These new 15″s have 5.55mm and 6.03mm of Xmax to move more air down deep…”

They'll make a difference, but it depends what you class as 'much', and compared to what.

The shorting rings are good; OK, not full symmetric drive (copper plating on the pole piece & entire VC gap) but a long step in that direction, and the lower distortion will be a positive. The physically smaller motors will reduce disruption / turbulence; given that they're quite limited BW units, I probably wouldn't run too far with that. The cast basket's nice though & probably won't ring any more than the stamped steel ones. I tend to find neo motors are a bit of a gimmick, but it's probably the pick of the two. The Beta would still be my choice though, sans further data (e.g. HD etc.) to go on.

Problem with the Neo magnets typically is being stronger they need a more sturdy spider to centre the coil in the gap , downside of this is the mechanical damping ( ie. Rms ) increases, Qm decreases, hence the thing works less well at low ( ie. room ) levels. Thanks due to JamesD for explaining this to me !

Truth there (assuming pistonic operation -under resonant conditions a different set of factors are in play, but that's rarely of significance for big woofers). There is also the issue that neo motors really don't like heat, hence the heat-sinks. They're good for tweeters, or can be -not necessarily so good for woofers.

Thanks everyone for the input, I'll go with the betas. When I win the lottery maybe I'll try the neos......

Ali Tait wrote: ↑Thu May 04, 2017 9:27 pm Yes indeed, think I'll stick to Betas for the new OB's.

Ali, are you going to make a thread about your new OB's?

Will be, though not sure when I'll get round to starting them.

Max N wrote: ↑Mon May 08, 2017 1:18 pm Thanks everyone for the input, I'll go with the betas. When I win the lottery maybe I'll try the neos......

No, buy the 15" field-coil Supravoxes !

IslandPink wrote: ↑Mon May 08, 2017 6:37 pm

Max N wrote: ↑Mon May 08, 2017 1:18 pm Thanks everyone for the input, I'll go with the betas. When I win the lottery maybe I'll try the neos......

No, buy the 15" field-coil Supravoxes !

Max might need 2 lottery wins for those...