[rklein]

Hi Duke:

Could the below waveguide be used in your 15"/ 98db version kit?

http://www.diysoundgroup.com/waveguides/seos/plastic-seos.html

Regards,

Randy

[JoshK]

I think this is a wonderful idea!  I am already working on a few speakers or I might be interested. 

I think you might talk with Erich about getting the SEOS waveguide.  Of course I am a bit biased as I helped design it.

[mcoaggie]

If I had this option when I built my troels DTQWT (DOUBLE TAPERED QUARTER WAVE TUBE).
I definitely would have sourced it locally instead.  Its a 10" 96db with wave guide.

 

[rave959]

This is exciting! 

The SEOS 15"/18" horn + a good 15" midbass and great x-over design.

I'll be looking after this thread!   

Cheers,
Ian

[Duke]

Hi Duke:

Could the below waveguide be used in your 15"/ 98db version kit?

http://www.diysoundgroup.com/waveguides/seos/plastic-seos.html

I think this is a wonderful idea!  I am already working on a few speakers or I might be interested. 

I think you might talk with Erich about getting the SEOS waveguide.  Of course I am a bit biased as I helped design it.

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

[Duke]

This is exciting! 

The SEOS 15"/18" horn + a good 15" midbass and great x-over design.

Assuming I can make it work, the smaller waveguide that rklein linked to would be my choice over the big one.   I would not have said that a couple of years ago, but having a bit more experience with juggling the applicable tradeoffs, I'm less averse to using what appears to be an "undersized" waveguide than I used to be.  All else being equal, the smaller the waveguide, the less energy ends up in higher order modes (HOMs).   

[JoshK]

P.S.  he also is having compression driver being made that is meant to be very similar to the DE250 but said to be a bit better in some regards and somewhere around the $50-60 mark.   Good for a high performance but budget minded kit.

[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

[JohnR]

Is the woofer a secret?

[Duke]

Is the woofer a secret?

I would rather get to the point where I've listened to a successful prototype before announcing what the drivers are.   

[pslate]

Does that 15" driver continue to impress? What else can you share about your sonic design goals for this project? I already have a large Scanspeak/RAAL monitor, and I am interested in owning a very different design like this one. Maybe I should have bought a Rythm Prism when I had the money, but I went the monitor route at the time, perhaps I can rectify matters with this kit. The monitor is great, I think I am just intrigued with the idea of living with radically different designs and seeing which I gravitate to over time. It would be my first project. Too dangerous for a beginner? Keep up the great work Duke. I am glad to see your bass cab doing so well.
Paul 

[Russell Dawkins]

I think I am just intrigued with the idea of living with radically different designs and seeing which I gravitate to over time.
Paul

I can relate to this. For a long time I lived with a pair of Tannoy Ardens (15" coax in large reflex box) and a pair of subs, plus a pair of Harbeth HLP3s (very small near field monitors) as alternates for judging my recordings. I almost never listened to the Harbeths, although their top end was creamy smooth - by comparison the Tannoys were coarse - and their mids were probably more accurate. The Tannoys were simply more fun and relaxed, due, I think to their ease with the loud bits. At that point I understood the appeal of larger drivers.
It seems there is no substitute for cubes, as the car guys say.

[Duke]

Does that 15" driver continue to impress? What else can you share about your sonic design goals for this project? I already have a large Scanspeak/RAAL monitor, and I am interested in owning a very different design like this one. Maybe I should have bought a Rythm Prism when I had the money, but I went the monitor route at the time, perhaps I can rectify matters with this kit. The monitor is great, I think I am just intrigued with the idea of living with radically different designs and seeing which I gravitate to over time. It would be my first project. Too dangerous for a beginner? Keep up the great work Duke. I am glad to see your bass cab doing so well.

Haven't had a chance to work with the new woofer anymore, beyond the initial measurements.  Until I've done some serious ears-on with tweeter & crossover, I really won't know which way I'm going on the woofer, but at this point it looks like I have two promising choices.

My goals are very good dynamics, no distracting colorations, tube friendly (though not tube dependent), and get the reverberant field right via pattern control & judicious juggling of tradeoffs.   Bass extension vs box size will be one tradeoff that the builder will have to wrestle with.   

[hoxuanduc]

Just a thought.  If you make the kit out of the Thunderchild cab you already have all the R&D done.

Duc

[rajacat]

Assuming I can make it work, the smaller waveguide that rklein linked to would be my choice over the big one.   I would not have said that a couple of years ago, but having a bit more experience with juggling the applicable tradeoffs, I'm less averse to using what appears to be an "undersized" waveguide than I used to be.  All else being equal, the smaller the waveguide, the less energy ends up in higher order modes (HOMs).

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.

With the larger waveguides, you can have a lower crossover. Is this just a series of tradeoffs? Hmm...I wonder what optimum size would be according to the numbers? The plastic 12" SEOSs are certainly a lot cheaper than the imported fiberglass ones. Maybe they'd be the most cost effective size/material for your kits. I think that Erich will eventually offer a larger selection of sizes in the plastic material in the future. Only 12" for now.

[Duke]

Just a thought.  If you make the kit out of the Thunderchild cab you already have all the R&D done.

Two problems with the Thunderchild as a home audio kit:  First, it's a 4-ohm load, and many if not most potential customers for a high-efficiency home audio kit will be using specialty tube amps (SET or OTL) that do better into a higher impedance load.

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!

[Duke]

Why do the larger waveguides have more of a problem with HOMs? 

Because more internal bounces back and forth are possible.

If that's the case why not go with the 10" SEOS?

It's a juggling of tradeoffs.  I've used the 12" JBL/Pyle waveguide with a 15" woofer with good results, but not sure I could do so with a 10" waveguide.

Isn't the HOM problem mitigated with the reticulated cell foam insert [in Geddes designs]?

Yes.  That's a patented technology, so I can't use it without permission. 

[brj]

Hi Duke.

Did you ever make any progress regarding your woofer evaluation?

Thanks!

[Duke]

Hi Duke.

Did you ever make any progress regarding your woofer evaluation?

Thanks!

Yes, I actually purchased and measured four different woofers because there were a couple others that showed up on my radar screen.   I have finished the woofer selection process but have not had time to do the crossover design.

Duke

[mjock3]

This sounds like something I would be interested in.