Question about Project May

[Niklas Nord]

What if the project may was like this.
crossed @ 80hz to some SUB1500

Would the design team still have tuned boxes for the
AL1500 or would it be sealed.
Does the AL1500 have better response tuned than sealed?

Will be great to hear about the listening impressions of the
loudspeaker!!

Looks big

[4313B]

"What if the project may was like this.
crossed @ 80hz to some SUB1500"

The driver to use on the bottom end could be the up and coming W1500H. This appears to be the VLF transducer designed to operate in a subwoofer with the K2-S9800 for HT.

"Would the design team still have tuned boxes for the AL1500 or would it be sealed. Does the AL1500 have better response tuned than sealed?"

When using subs I usually always run the mains sealed - best possible transient response.

[Niklas Nord]

So the 1500AL does have a nice frequency response if they are sealed to?

[4313B]

Good enough to meet a sub somewhere around 80 Hz.

[Niklas Nord]

Then if someone would be interested in building the project May loudspeaker,
there could be a recomended volume for sealed enclosure for the two AL1500

[Zilch]

I somebody just HAPPENED to have a couple dozen Sub1500's they still might consider using them, instead.

No matter how good it is, there seems little value in designing around a discontinued driver.

I believe all listeners at the audition agreed the Project May prototypes abruptly rolled off the VLF. The explanation will be forthcoming with further analysis, no doubt.

As for the listening impression, I reiterate, they were spectacularly good!

If they were to stop over here for about 6 months, I could say something more definitive about them, tho....

[korgroenewoud]

Hi Giskard,

When using subs I usually always run the mains sealed - best possible transient response.

I run two B 380's/bx 63 with main speakers S 3100 MK II. My problem is sometimes an overkill of the low mid-bass. I do not use the output of the bx 63. So the S3100's are not limited in their frequency response. They get the whole range, because the preamp output is balanced and the bx 63 is not. So the mains operate apart from the subs. If i seal the s 3100 cabinet, would that be an option. If i do, do you have to close the ports totaly, or with any damping material ? If you close the port totaly what will be the frequency response of the S 3100?

Thanks

Kor

[Earl K]

Hi Kor

You addressed your question to Giskard - hopefully he won't mind if I add my comments .

I have a .65cu' test enclosure that presently houses a le10a . This "test" enclosure is tuned to ( ??? well actually, I forget ). The tuning port has been blocked ( stuffed ) with rolled-up 1" road-case foam for about a year and a half .

This works very well . I measured the AC impedance of this setup quite a while ago. True to form, this sort of stuffing/plugging creates an aperiotic port. Ie ; the expected single impedance peak of a sealed box was in fact replaced with a very "broad and shallow, gently sloped hill ( impedance peak )" .

FWIW; Some types of amps, actually prefer this sort of "broad and low impedance peak" instead of the single sharp & narrow type impedance spike.

ie ; stuff the ports , the end result should work quite well .

regards <> Earl K

[korgroenewoud]

Hi Earl K,

Thank you for your quick reaction. If Giskard feels the need to say something extra he sure will do. I will try to stuff/close the port of the S 3100 MK II and see what the result will be. You will hear soon from me. Do you use subs too?


Kor

[Earl K]

Hi Kor

Do you use subs too?

In a nut-shell, no.

But, here's a brief system description ;

For about the last 2 years , I've been listening to a speaker setup that is always set, in an assymetrical arrangement. This happens to be the way I learn about what creates ( or destroys imaging/sound stage ). Both sides use the same horn drivers, as well as the same horns ( same amplification , crossovers , etc. ). The right channel uses an le10 and an le14 arranged in an MTM fashion around the current Altec 288-8K. The left channel is comprised of two JBL me150h 15" woofers , again arranged in an MTM fashion around the Altec 288. The midhorn is the Selenium H14-50. This 2" entry horn has a 1.4" to 2" adapter added to it, to accomodate the Altec driver. This setup loads, quite nicely to @ 750 hz . The 15(s) are in smallish cabinets (2.8cu') tuned to 40hz. They deliver pretty decent bass to about 60hz ( flat ) with 50 hz being about 3 db down (room loading helps out some ). The le14, in its small 1.5 cu' enclosure actually outperforms the 15(s) , in the area of bass extension ( though it's also, somewhat workng out of a corner ).

This setup looks like a "dogs breakfast" and is for R&D purposes only .

Therefore, pictures will never be published

regards <. Earl K

EDIT: I forgot to mention, if you still have too much overlap between your subs and the "stuffed-port" S3100mkII(s) - reduce the internal volume of your S3100(s) some ( keep the ports blocked ). You can easily reduce internal volume by filling up a pail full of sand. If spilling sand is a concern - make sand bags . I'd displace about 1 cu' of internal volume ( that = approx. 28 cubic litres according to my calculator ) .

ANOTHER EDIT: the previous should have read ;
I'd displace about 1 cu' of internal volume ( that = approx. 28 litres according to my calculator )

Okay,I admit it, I actually "failed" calculator in school and was demoted to "slide-rule" duty .

[korgroenewoud]

Hi,

I know that different low sections are what about the image not rather critical.
Nevertheless one le 10 and le 14 is something different than two me 150's.
But it depends on your room and your acoustical behaviour of the space the speakers are situated in. These 288 Altec drivers i've seen some 25 years ago at the dutch distributor. He showed us these huge drivers. I was very impressed. I bought at that time two Altec 411-8a (LF) and two 802-8a (HF). The 802-8a was a miniature compared to these big ones. The quality is fabulous. They are still in use and sound still very good. Thats quality.

Kor

[Earl K]

Hi

Nevertheless one le 10 and le 14 is something different than two me 150's.

Your dead right about that !

By the specs., and from more than just a cursory glance, these two drivers should not work together in this MTM setup.
But, despite all the following articulated strikes against them - I can assure you they work well together.

The "strikes against"; The two drivers have different sensitivities, and of course different tonalities ( though they are at least both aquaplassed ), plus they have somewhat different dispersion characterisitcs in their their top working octave and "horror of all horrors" a ported box is covering (some ) of the same LF response-range as the "sealed" box. The sealed le10 does put out a surprising amount of LF bass information. This information is quite measurable when "in or out" of the system. The fact that some of this' bass information is 90° out of phase with the ported boxes' LF, makes for a very interesting bass response. This LF "mix" isn't all that different from the "biamped" 4435 ( and its' LF phase quadrature - or 90° rotation ).

The other "strikes" mentioned turn out to be more "imaginary" than any real sonic disadvantage - when actually implemented . As it turns out, the MTM structure is "very forgiving" to all sorts of design "faux pas(es)".

I'll eventually buildup a permanent le14/le10 MTM setup, since I live in a smallish apartment. MTM(s) that use 15(s) - just take up too much space for this place .

regards <. Earl K

BTW, that W1500H woofer has a nice "beefy" look about it .

[lfh]

( that = approx. 28 cubic litres according to my calculator )

Actually it's only about 28 litres.

(Sorry, couldn't resist!)

[Guido]

The fact that some of this' bass information is 90° out of phase with the ported boxes' LF, makes for a very interesting bass response. This LF "mix" isn't all that different from the "biamped" 4435 ( and its' LF phase quadrature - or 90° rotation ).

Earl, could you explain this? I think the two 2234 woofers in the 4435 are in phase

[Earl K]

Hi Guido

When the 4435 is "Biamped" (only when ) ;

- I "think" that the 2234 which still has signal fed through its' large circuit inductor will be 90° out of phase with the 2234 that now has no inductor in it's signal path.

- I use the word "think" because I don't have any way to accurately measure this "expected" phase rotation. Therefore, I have no way to support the above statement.

- Though, I do "think" that the electrical theory on "passive" devices, supports me in this conjecture .
( I'll need to look for some text-based info that describes an inductors properties, ie; any "energy-storage" features )

<. Earl K