Open baffle speaker plans - how to remove the Neo3 PDR's enclosure?

[fjhuerta]

Hi all!

I'm trying to think of a good application for the Neo3. As many of you know, I've tried measuring the thing, and the results were a disaster. I know this tweeter can sound very good, but I can't really make it work to my liking. I suppose I'm crossing it over too low (2 KHz).

Anyway, I was thinking about an open baffle speaker using a pair of 80 / 100 Hz F-Mod inline crossovers and a subwoofer.

The plans so far are:

1) 15"~20" wide baffle, 44" tall.
2) Peerless HDS 8" woofers, MTM configuration
3) Neo3 PDR tweeter (maybe I'll have better luck with an open baffle).

(If these specs are too similar to Adire's (Dan Wiggins?) own open baffle speaker, it's no coincidence at all... I just happen to have the right drivers at the moment!)

I may design a strange, irregular front baffle shape if it helps tweeter diffraction (using Edge and BDS). I'm not so sure about it right now. The subwoofer is ready - a sealed Adire Tempest with a 300W plate amp.

The thing is that makes me wonder right now is....

How on earth can I remove the rear chamber of a Neo3, short of using my Dremel tool? I have no clue! It seems to be glued....

Would I have to destroy the tweeter in order to make it chamber-less?

[augerpro]

The measurments I've seen with the backplate removed are pretty bad.

[fjhuerta]

The measurments I've seen with the backplate removed are pretty bad.

The measurements I've made with the backplate on aren't too nice, either I haven't been able to understand what I am doing wrong.

[jkrutke]

Would I have to destroy the tweeter in order to make it chamber-less?

Get a razor blade and kind of "saw" underneath one corner. (careful when you do this) When you get about a half inch in, pry upwards and it will slowly come off.

I wouldn't say it measures badly with the rear chamber off, it's just very overdamped and response falls off from an excessively low Qts. You can still work with it, but you'll then have to tame a relatively hot top end, and there goes some of your sensitivity if you needed it. Additionally, be very prepared to tame the very extended low end... you run out of excursion easily if you don't. While the low end droops without the rear chamber, it doesn't really start rolling off until 600 hz. Without the rear chamber, output is 20 dB higher at 600 hz than with the chamber.

This tweeter isn't the smoothest measuring, and therefore, not the easiest to work with. But once the response curve is under control, you're rewarded with smooth non-fatiguing sound thanks to it's very low non-linear distortion.

I've got before and after response curves if anyone wants to see it.

[Jim Holtz]

Hi all!

I'm trying to think of a good application for the Neo3. As many of you know, I've tried measuring the thing, and the results were a disaster. I know this tweeter can sound very good, but I can't really make it work to my liking. I suppose I'm crossing it over too low (2 KHz).

Anyway, I was thinking about an open baffle speaker using a pair of 80 / 100 Hz F-Mod inline crossovers and a subwoofer.

The plans so far are:

1) 15"~20" wide baffle, 44" tall.
2) Peerless HDS 8" woofers, MTM configuration
3) Neo3 PDR tweeter (maybe I'll have better luck with an open baffle).

(If these specs are too similar to Adire's (Dan Wiggins?) own open baffle speaker, it's no coincidence at all... I just happen to have the right drivers at the moment!)

I may design a strange, irregular front baffle shape if it helps tweeter diffraction (using Edge and BDS). I'm not so sure about it right now. The subwoofer is ready - a sealed Adire Tempest with a 300W plate amp.

The thing is that makes me wonder right now is....

How on earth can I remove the rear chamber of a Neo3, short of using my Dremel tool? I have no clue! It seems to be glued....

Would I have to destroy the tweeter in order to make it chamber-less?

I'm not sure this will help but have you checked out the Plop in the Box design Dennis Murphy did with the Neo3? It has a 2K crossover and might give you some ideas to over come the issues your having. Here's a link. http://murphyblaster.com/content.php?f=newplop.html

HTH

Jim

[kestrel]

Sell them to me cheap and buy the NEO 3 without the chamber! :T

[Dennis H]

Javier, I assume you have Dan Wiggins' crossover design for the DDR. If not, grab it quick as Adire appears to be out of business.

DDRDipoleDesign.pdf

[fjhuerta]

John, thank you very much for your offer. I'd love to see the response of the non-chambered Neo3. I'll try to post later some of my measurements of the tweeter in a narrow baffle. I have measurements for both faceplates.

Jim, thanks for the info. Dennis' measurements are a lot cleaner than my own. He says he did them 15° off axis - I tried doing the same, but the response was still very ragged. Still, his crossover is very simple. I have to try something like it.

Kestrel -

Dennis, thanks for the info! I didn't know Adire was going out of business! Will they stop selling the Extremis? I'm sad I didn't get to try it. I love their Tempest sub, even today.

I'm now considering that, perhaps, I'm crossing it too low. I may try going to 3 KHz... so I'd have to forget about using the 8" woofers. Maybe I should try building the open baffle using the Seas 27TBFC, and crossing them over loooow.

[Eric H]

I read on another forum that RAW Acoustics bought the remaining stock of Extremis drivers, and that they are all gone. Creative Sound is said to be working on a "replacement", but probably not a carbon copy.

[pixelpusher]

Hi,
I'm a new member here but I posted measurements of the Neo3pdr with and without back cup on the Audio Circles forum. Check in the open baffle section. I am using the Neo3 in an open baffle 18" wide with no back cup. They certainly need equalization but I am very happy with the sound. I am crossing over around 2000hz 2nd order.
Regarding the removal of the back cup, I found that it helps greatly to scrape off all of the adhesive from the outside of the seam area with a sharp screwdriver before attacking with a utility knife. It's not really that hard. The second one went much better for me than the first.
I made and measured a test baffle with a shallow waveguide that shows some promise of improving the low end droop and will also time align the Neo3 with my midrange. Currently am building finished waveguide baffles.

[Dennis H]

Thanks for the measurements pixelpusher. Here's a link to the thread.

http://www.audiocircle.com/circles/index.php?topic=36426.0

Your measurements start on page 4 and look quite good to me. I think JohnK and Davey are getting bad results from centering them on a small baffle. John centered on 11"x17" as I recall and I get very similar results with a 'perfect' dipole driver modelled in the Edge. Much of what John is seeing is baffle effects that can be fixed quite a bit by baffle sizing and golden ratio driver positioning.

[Dennis H]

Here's what the Edge does with a 'perfect' dipole driver on a couple of different baffles. I sim'd a rectangular driver with a radiation area 1" wide and 1.5" tall.

First centered on an 11x17 baffle.



Next a 13x40 baffle with the driver 3" from the top and 5" from one side.

[capslock]

Neo3 with and without cup were measured in HH and KT magazines years ago. Without cup, F3 is much lower, and distortion is also significantly lower throughout the pass band. FR didn't look bad without the cup in an infinite baffle.

Is Adire really out of business?

[Davey]

Any of you fellas hear any further news on Adire?

Davey.

[ThomasW]

Adire abandoned the DIY loudspeaker business, this is old news.

They remain in the OEM loudspeaker business

[augerpro]

CSS is developing a replacement for the Extremis though. It's called the SDX7. XBL2 motor again but I have no idea what else will be the same.

[Chris7]

Not to push this thread off topic... perhaps this would be a better question for a new thread, but does anyone have any links to any threads that explain what happened to Adire? I've searched around and I can only find bits and pieces of various aspects to the story (service delays, months of non-contact with customers, failure rate claims and denials regarding the new products from Chile, CSS offering trade-ins for failed products, disputes and allegations concerning authorized retailers, closing of one of the Adire forums, etc.).

[Dennis H]

I think (but don't know) trying to go bigtime with the Chile factory, and that not working out, was the beginning of the end. I'm guessing Dan lost a ton of money on the deal. Too bad......

[fjhuerta]

For the record - I did take off the rear cup, and will try to build a dipole using the Neo8 / Neo3 driver.

[Chris7]

I think (but don't know) trying to go bigtime with the Chile factory, and that not working out, was the beginning of the end. I'm guessing Dan lost a ton of money on the deal. Too bad......

I was guessing that. It looks like Adire may not be in the OEM market for much longer either. There's a post on AudioCircle from about a month and a half ago from the vendor of some kits using the Adire Extremis saying that there was a 90% chance he wouldn't be able to get any more of the Extremis drivers.

[Davey]

Adire abandoned the DIY loudspeaker business, this is old news.

They remain in the OEM loudspeaker business

Yeah, I was aware they dropped the DIY portion of their business, but it sounds like they're out of business on the OEM side of things also.

I was just wondering. Sorry for the stupid question.

Davey.

[Dennis H]

FWIW, Dan Wiggins surfaced over at diyaudio. Sounds like his new gig is as a hired gun (consultant) for the big companies.

http://www.acousticdev.com/

[Landroval]

For the record - I did take off the rear cup, and will try to build a dipole using the Neo8 / Neo3 driver.

Any progress?

Have anyone tried the Neo3 without rear cap in a tuned rear chamber? If so, what kind of chamber size are we talking about?

[fjhuerta]

No, I re-sealed the chamber. After a couple of posts, I decided it wasn't worth it to have a dipole from 700 Hz up (with the Neo8).

I'll fight that tweeter again on a WT-M config.