[mightym]

Duke, I'm a little late to this party, but interested all the same.

Missed you at LSAF this year, the scuttlebut was that you were moving?  Possibly what you intimated to me last year at said same show....?

Have you had time to work on the XO's yet.

Inquiring minds want to know....

John

[Duke]

Duke, I'm a little late to this party, but interested all the same.

Missed you at LSAF this year, the scuttlebut was that you were moving?  Possibly what you intimated to me last year at said same show....?

Have you had time to work on the XO's yet.

Inquiring minds want to know....

Yes, Lori and I have the house up for sale, hoping to move to the north-of-Dallas area.

I have done my measurement suites and have the data I need to design the initial iteration of the crossover, and am working on that step (among other things).  Once the inital design looks good on paper, I'll build-measure-refine until the measurements look good, then I'll move on to listening tests (which usually leads to more refinements).

[jtwrace]

Yes, Lori and I have the house up for sale, hoping to move to the north-of-Dallas area.

Dallas, Texas?   

[rklein]

Thanks for the suggestion, rklein and JoshK!  I just pre-ordered a pair so I can check them out.   Looks very promising.

Based on the above, I also just pre-ordered a pair as well.

And yes, Josh is correct about the compression driver that Erich over at DIY Sound Group is having manufactured which looks very promising.

Regards,

Randy

Duke:

Did you ever receive your Seos Waveguides?  I have yet to hear anything since I ordered mine.

Regards,

Randy

[EDS_]

Yes, Lori and I have the house up for sale, hoping to move to the north-of-Dallas area.

I have done my measurement suites and have the data I need to design the initial iteration of the crossover, and am working on that step (among other things).  Once the inital design looks good on paper, I'll build-measure-refine until the measurements look good, then I'll move on to listening tests (which usually leads to more refinements).

If you decdie to pull the trigger on the North/North of Dallas notion up let me know.  I'm a DFW lifer and know the area very well.  It's an area inwhich one requires an expert real estate agent - independent shcool districts, hundreds of towns and cities, limited public transportation and no end in sight to the growth, planned highway construction that will make some commutes 405-like for a number of years - you get my point.

After thinking about your potential kit offerings I'd be extremely interested in the best sound with an eye towards the smallest foot-print/WAF combo.

[kevinh]

Why do the larger waveguides have more of a problem with HOMs? If that's the case why not go with the 10" SEOS? Geddes had the 15" Summa which supposedly sounded better than the Abbey. I've noticed that he's no longer offering the Summa but still has the Abbey, the 10" Nathan and the 8" Harper. Would the Harper have the least problem with HOMs? Isn't the HOM problem mitigated with the reticulated cell foam insert? Some think that the SEOS will have less problem with HOMs than the Geddes style WG. Early reports have been very positive.

You can DIY the foam, this stuff could work to reduce HOM's it would cost you a little efficency.

http://www.thefoamfactory.com/opencellfoam/filter.html

[Duke]

You can DIY the foam, this stuff could work to reduce HOM's it would cost you a little efficency.

Imo the crossover would need to be designed with the foam in place, as does attenuate the energy that passes through, the shorter wavelengths moreso than the longer ones. 

[nullspace]

Hi Duke,

Just curious -- any update on the kit? Hope the move went well.

Regards,
John

[einis]

Second, Eminence's rules don't allow me to sell custom woofers (like I'm using in the Thunderchild 12 and 15) unless they are in a finished cabinet - in other words, I can't offer them in kits.  Sorry!

what? a long list of brands supply custom eminence kits for years. ex. these:
http://hawthorneaudio.us/products/
http://www.bastanis.com/kits.html
hawthorne have sold hundreds of coaxdrivers, without any cabinet or even a drawing (open baffle)
thats wierd if you got that response from eminence :/

[Duke]

Update - the compression driver that I want to use in the kit will finally be available some time in November, according to the manufacturer.  I have tested a sample and am very happy with it.  It's a polymer-diaphragm driver that goes up to an honest 20 kHz, and it isn't outrageously expensive.  The only other polymer diaphragm compression drivers I know of that go up to 20 kHz are very expensive, and I do not like their internal geometry as much.  The tradeoff that this new driver makes is, both its efficiency and its power handling are fairly modest by compression driver standards, but that's not going to be an issue until we start pushing 118 dB or so.   

[brj]

Glad to hear you're making progress, Duke!

Would you mind elaborating a bit regarding what bothers you about the internal geometry of the other drivers you looked at, or conversely, what features you specifically look for in terms of internal geometry?

It also sounds as if you were specifically targeting a polymer diaphragm.  Is that an acoustic or engineering derived preference?

By the way, were you targeting a specific throat diameter to match a given waveguide, or were you looking at the driver regardless of opening and then finding a waveguide to match?

No need to spill any secret sauce if you don't want to - I'm just always curious about the logic and motives that drive the specific compromises inherent to speaker design.

Thanks!

[Duke]

Would you mind elaborating a bit regarding what bothers you about the internal geometry of the other drivers you looked at, or conversely, what features you specifically look for in terms of internal geometry?

What I look at is how the internal geometry of the compression driver matches up with the horn or waveguide geometry.  So what works really wall for one pairing might not work so well for another. 

It also sounds as if you were specifically targeting a polymer diaphragm.  Is that an acoustic or engineering derived preference?

I generally prefer polymer diaphrams because a) I think they are less likely to sound edgy and b) they don't have a spike in the response that I have to deal with.   Now there are metal diaphragm compression drivers that behave very well, but none that have the combination of characteristics I'm looking for in this case.

By the way, were you targeting a specific throat diameter to match a given waveguide, or were you looking at the driver regardless of opening and then finding a waveguide to match?

Yes, 1" throat.   That size will go higher than a large-format driver (1.4" to 2" throat), still go low enough for my target crossover, and the cost is far less.  Also I like the available off-the-shelf options in horns and waveguides better at 1" throat than in the larger throat sizes.   While it is possible to get wide pattern coverage up high with a large-format compression driver, you have to use some sort of diffractive horn, which I try to avoid.   So now we're looking at a three-way if we want to do justice to the top octave.  I'm not saying you can't build a killer system around a large-format compression driver, but it's considerably more expensive and complicated to do so. 

[roscoeiii]

Any idea where the crossover point will likely be located now that you have a driver chosen?

[Duke]

Any idea where the crossover point will likely be located now that you have a driver chosen?

1.5 kHz ballpark.  Yeah I know that seems high for a 15" woofer, but this particular woofer's off-axis dispersion holds up better than most 12" woofers.  When I launch the kit I'll post the identity of the drivers, and you'll be able to look at the off-axis data and see what I mean. 

[nullspace]

Sounds like you're making great progress, Duke. Looking forward to seeing how it turns out.

Did you ever get a chance to check out the SEOS horns? If so, your impressions? I have a pair laying around, but haven't yet gotten to do anything with them.

Regards,
John

[Duke]

Did you ever get a chance to check out the SEOS horns? If so, your impressions? I have a pair laying around, but haven't yet gotten to do anything with them.

I have not received mine yet, but expect to soon.  Was in communication with Eric yesterday.

[nullspace]

How about I send you mine? They're just sitting in a box. My wife and I are in the process of moving and it'll be months before I do anything with them.

Regards,
John

[Duke]

How about I send you mine? They're just sitting in a box. My wife and I are in the process of moving and it'll be months before I do anything with them.

Regards,
John

Thank you, John!  But I think mine are being shipped in the next day or so.  Apparently Eric had sent me an e-mail some time ago and I missed it (probably went into my spam folder and got deleted), and that derailed the communication between us and delayed the shipment. 

Eric is also sending me a smaller waveguide, something that used to be available in the US a couple of years ago and then was discontinued.   The availability of this smaller waveguide through Eric allows me to revisit another project that has been on the shelf for the past couple of years. 

[nullspace]

Hey Duke,

I hope things are well. Any update on the kit?

Regards,
John

[Duke]

Hi John,

Still waiting on that shipment of compression drivers.  In the meantime I managed to snag a couple from Europe and get started on the crossover design.   

Duke