[wendelltate]

Hi Everyone.  I have been playing around with a "new to me" design.  I am looking for some advice on a couple of things...
What I have here is a Eminence Alpha 15a in an H-frame using the Martin King crossover which is around 200hz.

The full range is a Mark Audio 10p on an 18"x18" baffle that has a 2" deep frame on the sides and top.  I really love the natural sound of these drivers on open baffles...I am using a 100uf cap on the MA which should put it around 200hz as well.  Maybe this should be 300hz?  I might also add some L-Pads to adjust the level...

I also have a pair of SB Acoustic SB29 tweeters that I would like to use for the high end.  I was planning on crossing those in around 7000 and using L-pads to control the volume of these.

Would it be okay to simply add the tweeters to the baffle that I already have?  If so, is it okay to place the tweeters an inch above the MA speakers?

Is there anything else that I need to be looking at with these?  Thanks for the help.

[wendelltate]

I have been doing some tinkering with this setup. Inspired by the new Vinnie Rossi stiletto speaker design and a number of other open baffle designs, I decided to make the baffle more narrow.
I also wanted to try out a u frame for the sub. If I understand correctly, the depth for an alpha 15 should be around 8"or 9"? And it should be dampened as well?
At the moment I'm using my many tsp to play with the crossover on these. I have the mark audio running full range and the alpha crossed at 275. I have a single 2.2 capacitor on the tweeter.
Am I correct in understanding that the depth of the u frame is half of the hframe?
Thanks

[FullRangeMan]

Nice project, unless for the tweeter add, there is no practical or musical reason to use such driver hence the Alpair 10P reach 20kHz easily, w/the Alpair you will have the rare feature of a midrange and one tweeter, both OB and Dipole in the same driver with the rich organic tone of a paper cone.

With tweeter you will have:
more parts, more price, more labour
more 2 xover legs to detracte the music
you will have less SPL due the xover presence
tweeter are monopole drivers that emit sound only to front

[walkern]

Curt Campbell did a bass reinforced design (not open baffle) using the Mark Audio 10P as a mid/tweeter, and he selected a first order crossover between the bass drivers and the MA at 400hz.  You can see more about the design here:http://speakerdesignworks.com/Halcyon_1.html

And I agree with FullRangeMan that the addition of the tweeter is adding complexity to the system for little or no sonic benefit.  The 10P (which I love!) has plenty of extension to the top of the human hearing range.

Neil

[wendelltate]

Thanks for the input. I will definitely do some listening without the Tweeter. I guess I didn't realize that the markaudio would go all the way to 20k.
I'm going to do some more reading about the depth of u frame vs h frame enclosures as well. I have the speakers in a fairly small room and if I can make the subwoofer enclosure smaller, that would definitely be better for my space.

[FullRangeMan]

I guess I didn't realize that the markaudio would go all the way to 20k.

This not your fault, mark audio dont inform the freq range so people think this driver is a midrange and should be used with a tweeter.

[planet10]

...so people think this driver is a midrange...

A midrange? It certainly can do that, but listen to a pair in something like FHXL and you’ll know it is pretty good all by itself.

dave

[FullRangeMan]

A midrange? It certainly can do that, but listen to a pair in something like FHXL and you’ll know it is pretty good all by itself.

dave

Wonder if the FHXL enlarge the SPL output from the driver.
How much is the FHXL gain in the above 300Hz range?
Gracias

[planet10]

No gain above 300 Hz. Enuff gain below that that sometimes more damping is needed to reduce bass output (depending on room placement)

SPL midband is 90dB.

dave

[FullRangeMan]

No gain above 300 Hz. Enuff gain below that that sometimes more damping is needed to reduce bass output (depending on room placement)

SPL midband is 90dB.

dave

Very interesting, I dont knew this, seems useful to a small tbe amp.
So seems a woofer not required, and being a Dipole looks a option Mr.Wendell should consider.

[planet10]

A10p (and almost every other FR) will need help on the bottom in an OB. A tweeter will often take away more than it brings.

dave

[JohnR]

Thanks for the input. I will definitely do some listening without the Tweeter. I guess I didn't realize that the markaudio would go all the way to 20k.
I'm going to do some more reading about the depth of u frame vs h frame enclosures as well. I have the speakers in a fairly small room and if I can make the subwoofer enclosure smaller, that would definitely be better for my space.

My advice is don't pay too much attention to the naysayers. What you do need to do (IMO) is get set up to with acoustic measurements so you can be more rigorous with your design work. If you do that, you will learn a number of things, including the actual frequency response of the drivers on the baffle, their dispersion pattern, and that a fullrange driver stops being dipole anyway at a certain frequency. And with some more effort you'll then be able to implement a proper crossover, which is the only way you will be able to evaluate whether the tweeter brings benefit (to you).