Coming soon...

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Duke

Coming soon...
« on: 15 Oct 2015, 08:46 pm »
Here's a design that's almost finished, thought I'd give a sneak preview:



I'm fairly confident that's a woofer you haven't seen before.  To the best of my knowledge you're looking at the first pair to come into the US, thanks to jtwrace hooking me up with some of his European friends in high places. 

The main reason for two woofers is, better (less) interaction with the floor, and more midbass power in the Cello region, where imo many speakers fall a bit short.  We also get better pattern-matching with the waveguide in the crossover region. 

There are a few things going on which aren't apparent from this angle that I think will make this an exceptionally competitive and adaptable design.  I'll spill the beans on one of them:

Each woofer has its own separate sub-enclosure, along with pluggable ports, so it's possible to stagger the tuning frequencies of the two sub-enclosures, or even go with one vented and the other sealed. 


roscoeiii

Re: Coming soon...
« Reply #1 on: 15 Oct 2015, 09:03 pm »
Look forward to hearing more about this one Duke!

Freq response
Crossover point
Efficiency

And most importantly: Listening impressions!!!

Duke

Re: Coming soon...
« Reply #2 on: 15 Oct 2015, 10:12 pm »
Look forward to hearing more about this one Duke!

Freq response
Crossover point
Efficiency

And most importantly: Listening impressions!!!

Typical bandwidth is 30 Hz to 20 kHz (-3 dB), in-room.  This assumes some boundary reinforcement, but not a great deal.  In a large room and/or where boundary reinforcement is scarce, the -3 dB point moves up closer to 35 Hz.  With generous boundary reinforcement and/or with a low-damping-factor tube amp, and re-tuning the enclosure accordingly, we should get down into the mid-to-lower 20's (without boom).   

Crossover point is about 1.4 kHz.

The 2.83-volt sensitivity is about 90 dB, which means that it'll be comparable in loudness to a 90 dB, 8 ohm speaker, when driven by a solid state amp.  I won't know for sure what the impedance curve looks like until the final tweaking is done, but my guess is that the system impedance will probably be a little higher than 8 ohms.  It will definitely be tube-amp-friendly, but not SET friendly.   (A SET-friendly system is also in the works.)

Note that I base my efficiency and voltage sensitivity claims on the woofer's T/S parameters, which is a fairly conservative yardstick.  I once had an amplifier manufacturer compare a set of my speakers side-by-side with a competitors' which were 8 dB more efficient "on paper", and he said they behaved as if they were the same efficiency.

I do most of my tweaking in mono because stereo imaging can be distracting from the task at hand.  Then the final fine-tuning is done in stereo, and since you're looking at the only two such woofers in the US, I haven't been able to do that yet.   The US importer should be getting some within the next several weeks, at which point I'll be able to get a second pair and finish the fine-tuning. 



rajacat

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Re: Coming soon...
« Reply #3 on: 15 Oct 2015, 10:21 pm »
Very nice design!
Can these be placed right in the corner because of the waveguides' control over directivity? How will that affect imaging?

Duke

Re: Coming soon...
« Reply #4 on: 16 Oct 2015, 12:08 am »
Very nice design!
Can these be placed right in the corner because of the waveguides' control over directivity? How will that affect imaging?

Thank you!

Yes, these speakers have good enough directional control, and enough bass tuning adjustability, that they can go right smack in the corners.   

As for imaging, left-to-right image placement should hold up quite well but soundstage depth will probably be degraded.  That being said, one of the features I'm keeping under my hat for now should theoretically improve the soundstage depth beyond what we'd normally get with corner placement.  But I won't be able to really test it out until more woofers are available so I can finish the other speaker and listen to a stereo pair.

jtwrace

Re: Coming soon...
« Reply #5 on: 16 Oct 2015, 12:28 am »
I look forward to hearing these somehow; somewhere.

Phil A

Re: Coming soon...
« Reply #6 on: 16 Oct 2015, 01:16 am »
They look nice.  I remember those old Alison 3s that were made for corner placement.

Duke

Re: Coming soon...
« Reply #7 on: 16 Oct 2015, 02:12 am »
I look forward to hearing these somehow; somewhere.

I hope so too!  Not sure at this point what shows are in my future, nor what I'll be bringing, but right now I'm not inclined to show another big complicated many-piece system anytime soon. 

They look nice.  I remember those old Alison 3s that were made for corner placement.

Yes!  Allison thought outside the box long before someone coined that phrase, and he came up with some very innovative designs.  Did you ever get a chance to hear the Snell Acoustics Type A?  It was a magnificent embodiment of Roy's ideas. 

RDavidson

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Re: Coming soon...
« Reply #8 on: 16 Oct 2015, 02:28 am »
Very nice. :thumb:
What are the overall dimensions?

Duke

Re: Coming soon...
« Reply #9 on: 16 Oct 2015, 02:51 am »
Very nice. :thumb:
What are the overall dimensions?

Thank you!

42 inches tall, 13 inches wide, 20 inches deep on the deep side, and 10.5 inches deep on the shallow side.  I haven't weighed it yet.

fakamada

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Re: Coming soon...
« Reply #10 on: 16 Oct 2015, 06:30 pm »
Can you reveal brand of woofers?

Duke

Re: Coming soon...
« Reply #11 on: 16 Oct 2015, 07:11 pm »
Can you reveal brand of woofers?

Not just yet.   I want to get this and possibly one other product officially launched first, and after that, we'll see. 

Phil A

Re: Coming soon...
« Reply #12 on: 16 Oct 2015, 07:12 pm »

Yes!  Allison thought outside the box long before someone coined that phrase, and he came up with some very innovative designs.  Did you ever get a chance to hear the Snell Acoustics Type A?  It was a magnificent embodiment of Roy's ideas.

Yes - heard the Snells.  Back in the old days when I couldn't afford as much I lusted after those and the big ADS models too.

woodsyi

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Re: Coming soon...
« Reply #13 on: 16 Oct 2015, 07:21 pm »
Ha,

I still have a pair of Allison 3s with blown twitters. :roll:

This looks interesting, Duke.