[D OB G]

Hi Erling,

Yes, I have done a bit of work to the Dayton. 
The plasticine varies between 2 and 4 cm thick (on the outside).
The foam starts at the exit from the adaptor to the mouth, about 13 cm thick. 
(It didn't sound good putting it into the adaptor, nor did it sound good in the diffraction part of the 18sound).

I stated in the past that I didn't prefer the DE250.
I didn't try all the combinations!

From worst to best:

DE250 in 18sound
18sound in 18sound
18sound in Dayton
DE250 in Dayton

Dayton say the waveguide maintains control down to 1.2 kHz.
This is true when measured, but, as you say, there is some harshness down that low.
It seems the old rule of using a horn one octave above it's cut-off applies even in this case, because all harshness is gone by 2.4 kHz.
The foam improves it more.  Much clearer and "smoother".
With the DEQX I can get it extremely flat.

Having said that, I haven't tried the Neo's!

Interesting to see that you use the 6ND430 so similarly!!

What options would you have to change the Alphas?

Regards,

David

[scorpion]

Hi David,

Guess I have to work some more with the Daytons to achieve max results. It has been suggested to cut away the screwmount altogether and attach the driver directly to the horn with a mouth of the right size. By the way my waveguides fall in hornload over 6 kHz quite a bit, didn't you experience the same ?

Regarding the Alphas I guess that I have become more critical when mid and top are so good. It is not the attack but rather the decay and ultimate cone control that bothers me. Or at least what I think I hear. Rather what high Qts-elements usually are accused of. I am certain that the Alpha15s will behave better i H-baffles but then you will have to live with a great size installation. Two 15"ers on a flat baffle is big enough. So I have started some experiments down an entirely other road. More about this later if things work out.

Here is a response measurement of the 6ND430 and Neo 3 combination indoors in my livingroom at listeningposition about 15 degrees off axis. There is a 6 dB shelving on the 6ND430 from 300 Hz downwards to compensate for baffleloss at crossover 200 Hz, otherwise there are no corrections applied:




/Erling

[D OB G]

Hi Erling,

I'm certain that it would have been best if I had made a flange on the Dayton after cutting off the threaded portion.

With regard to frequency response, here is the graph of the compensation curve DEQX applies.  i.e the inverse of the frequency response.





It seems to exhibit the approximately 6 dB per octave slope that would be expected of a constant directivity waveguide.  (Good level matching betweeen the DE250 drivers!)

Your frequency response results are excellent, aren't they!

Regards,

David

[scorpion]

Inspired by 'The Audiosyncrasy' I remodelled my present outfit like this:




Baffles are glulam spruce. For Alpha15s two 40 x 50 cm, 2.8 cm thick (16" x 20" x 1.1") are put together with piano hinges. 18 Sound 6ND430 and B&G Neo3W (no back cup) sit on a 20 x 60 cm 1.8 cm thick (8" x 24" x 0.7")  baffle. Crossovers via Behringer SRC 2496 and DCX2496 are 48 dB/octave at 250 Hz and 2 kHz, no EQ required. Sound is pretty good.

/Erling

[Rudolf]

Hi Erling,

nice to see another less wood consuming design.

Is it just "trying something else" or do you consider it as an progress in general? If the latter, I would be curious, what you find to be the most remarkable improvement(s).

Did you play with the angle between the woofers? I could imagine that it might help to better control room modes. What's your take on this?

Rudolf

[JohnR]

Hey... nobody can view images that big...

[panomaniac]

Yeah, about 1/3 that size would make for better viewing. (like 800 pixels high, max).

Interesting design!

[scorpion]

Right Guys, size edited. 
I'll come back with some more thoughts about why this.

/Erling

[D OB G]

Hi Erling.

Good to see that you too are having success with the 6ND430.

My main reasons for configuring the woofers on an angle were twofold.

First, to keep bass vibrations completely separate from the the mid/tweeter baffle, where the much smaller movements seem to me to be vulnerable to modulation (it certainly sounds more detailed to me this way).

Second, with the way I implemented the woofer baffle, to reduce vibrations in absolute terms by attaching welded brackets to the baffle, which were then bolted to a baseboard.  By doing this I believe I sort of "triangulated" the baffle.   

I'm not sure that the dispersion would be altered much at bass frequencies??? (I could be wrong ! ).

BTW I've changed the tweeter to the BMS 4540nd.  Better detail and "sparkle" than the DE250.

Regards,

David