Emminence 15 module

I have been thinking of some ideas to augment the bass of my tritrix "parts-express" speakers. One idea is to implement one emminence 15 driver in a H-enclosure per channel like in the thread below. I would use an active cross over and drive it with a digital amp while driving the tri-trix with my tublab amp.

http://www.diyaudio.com/forums/multi-way/173978-has-anyone-used-alpha-15-two-way.html

Has anyone else tried this?

However, I wonder if I should just get sub-woofers. The main application is for music with 5% movies. Please comment.

Thanks
Salsero
 
I've had these for a couple weeks now and think they are the most natural and detailed bass I've every heard. If you go with MJK's "H" frame dimentions of 16" x 16" baffle board and 7.5" box frame on eighter side of the baffle board, they go a lot lower then you might expect. I think they are either fs of 28hz or f3 of 28hz. Either way any music you play on them will sound great.
 
I second djn's support for the Alpha 15A in an H-frame. Keep in mind the H-frame has a rising response and you'll need to roll it off around 120 Hz using a 2nd-order slope. I think the F3 is a more conservative 32 Hz depending on how you calculate it.

I'm not sure what the sensitivity of the tritrix is but you should expect that the Alpha in this configuration will be around 85 db/1 watt/m. You'll probably need to use a plate amp to match. Check the specs for the plate amp carefully though. Many implement a 4th-order filter rather than the 2nd-order one needed.
 
I've been "playing" with the very cheap but relatively low-powered Dayton SA70 plate amp from PE (Dayton SA70 70W Subwoofer Amplifier | Parts-Express.com). Because they are inexpensive I bought 1 per side.

I think that all the other plate amps that PE offers have 4th-order slopes (24 db/octave) - unfortunately this info isn't published for many that they offer. The Keiga plate amp line available through Madisound (such as https://www.madisound.com/store/product_info.php?products_id=368) are powerful, but more expensive, amps with 2nd-order slopes. If I had to do it over I'd spring for a Keiga amp first. You can use one and feed two H-frame modules.

The crossover is built into the plate amp. If you do chose to go fully active you'll need the Behringer DSX2496 (http://www.parts-express.com/pe/showdetl.cfm?Partnumber=248-669) or better to get 2nd-order slopes plus seperate amps which will be much more expensive.
 
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Hey Holdent, I am getting a pair of those SA70 plate amps Saturday. It is a swap deal. How do they work in your system? Right now I am running the Alpha 15a full range with Fostex FE126E running full range. It all sound VERY VERY good and I am still blown away by the bass in an "H" frame. However, I think I am getting just a bit of muddyness in the midrange without the crossover.
 
Hi,

Had a quick look at the photos in the other thread. A quick suggestion - puttting some stuffing in front of and behind the 15" driver will reduce it's midrange output somewhat, so you'll just be hearing the Fostex. Apart from that, a temporary inductor will work... Or just wait until Saturday.
 
However, I think I am getting just a bit of muddyness in the midrange without the crossover.

Just a bit? I'd be surprised. I ran the alpha 15s open over visaton B200s for a while to break them in and while it was a nice warm fat sound, the alpha is not exactly clear in its upper reaches.



holdent wrote: If I had to do it over I'd spring for a Keiga amp first. You can use one and feed two H-frame modules.

many of these limit crossover to 100hz or lower, which may be a bit low
 
Plate amp?

On the plate amp recommendation, do plate amps provide good sound quality? It seems like an active cross over in addition to an amplifier for less than $200 is interesting. I was thinking of using the one from audio-kits (link below) and a digital amp from 41hz.com. Let me know what you guys think. I certainly do not have experience here.

Active crossover kit

On the emminence alpha, is there a better 15" drive for less than $150?

thanks
Salsero
 
djn - I utilize the high level inputs on the plate amp as I'm not using a seperate preamp. I set the low pass filter at approx 120 Hz. I use passive 2nd order high-pass filter to run the fullrange driver paired with the H-Frame.

Salsero - the active xover you link to is a 4th order one. For the H-frame application you need a 2nd order filter to roll-off the rising response of the H-frame. Additionally with this xover it appears that you must select a specific xover frequency thats the same for both the low- and high-pass filters. If you read Martin King's H-frame project (http://www.quarter-wave.com/Project08/Jordan.pdf) he selected different electrical xover frequencies to arrive at the correct acoustic xover in the system. In his case he used a 2nd-order low-pass filter of 100 Hz, and a 2nd order high-pass filter at 250 Hz. The resulting acoustic crossover comes out looking like a 2nd order one at 250 Hz.

There isn't any reason you can't do this actively - its just that this xover does appear to be suitable.
 
Active XO unit for subs

If you're not familiar with the reckhorn F-1 check it out at CSS. I was running a plate amp crossover on my sub for a while with my Fostexes. My reckhorn results in better sound quality in both the high end and the low, and better integration between the two. The plate amp was relatively uncivilized in comparison, though the low cut was a benefit even so.

Creative Sound - Product Details

It could probably be hotrodded, but I haven't put in the effort...
 
Though the F1 from Reckhorn looks good, it has a 4th order low-pass filter built in and won't work as well as a 2nd order filter for an H-frame. You'll also need an amp to go with the F1. Incidently the Reckhorn site lists the F1 as "sold out" - you might not be able to get it from CSS.
 
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