Drivers
The woofer is the GR Research
M130, the tweeter a Scan Speak D2010/851300.
The M13 is a highly competent, 5.5" mid/woof that can be had for $24. I consider it to be a value lead in this category. It can produce adequate bass for music, and has a very good midrange for a $24 woofer.
As you can see, it has an extended high-end response, lacking only the top octave.
The SS 8513 is a reasonably priced, high-quality tweeter which has been used in some very high-priced commercial systems, including the well-regarded ProAc response 2.5, which currently sells for an astounding $4,500/pr.
The M13 is a highly competent, 5.5" mid/woof that can be had for $24. I consider it to be a value lead in this category. It can produce adequate bass for music, and has a very good midrange for a $24 woofer.
As you can see, it has an extended high-end response, lacking only the top octave.
The SS 8513 is a reasonably priced, high-quality tweeter which has been used in some very high-priced commercial systems, including the well-regarded ProAc response 2.5, which currently sells for an astounding $4,500/pr.
The Box
I am currently using a sealed box, although I'm finding it a bit weak in the
low-end. I mean to try porting the box, but just haven't gotten around to it yet.
The box is 12 1/4" x 7 1/2" x 9" (HxWxD) and made from 3/4" MDF. It is moderately stuffed with PolyFil. If you want to try porting this box, I calculated a 1 1/2" x 3" port to be the proper value for this box. If you choose to use my box, you can plug the port (an old sock works well:)) for use with a subwoofer or leave the port open for use on it's own. If you use this speaker for Home Theater, you will definitely need a subwoofer, as the little 5.5" woofer cannot handle the low bass that many DVD producers seem to love so much these days.
The drivers are centered on the baffle, the tweeter 2 1/2" from the top, and the woofer 7" from the top. The tweeter must be flush mounted, and the woofer surface mounted. The woofer will overlap the flange of the tweeter.
If you chose to roll your own box, make sure you keep the baffle width at 7 1/2", and keep the driver layout the same. My woofer measured as follows:
FS: 52.7Hz
Re: 5.5 Ohm
Qms: 2.9
Qes; 0.5
Qts; 0.43
Vas: 13.7L
The box is 12 1/4" x 7 1/2" x 9" (HxWxD) and made from 3/4" MDF. It is moderately stuffed with PolyFil. If you want to try porting this box, I calculated a 1 1/2" x 3" port to be the proper value for this box. If you choose to use my box, you can plug the port (an old sock works well:)) for use with a subwoofer or leave the port open for use on it's own. If you use this speaker for Home Theater, you will definitely need a subwoofer, as the little 5.5" woofer cannot handle the low bass that many DVD producers seem to love so much these days.
The drivers are centered on the baffle, the tweeter 2 1/2" from the top, and the woofer 7" from the top. The tweeter must be flush mounted, and the woofer surface mounted. The woofer will overlap the flange of the tweeter.
If you chose to roll your own box, make sure you keep the baffle width at 7 1/2", and keep the driver layout the same. My woofer measured as follows:
FS: 52.7Hz
Re: 5.5 Ohm
Qms: 2.9
Qes; 0.5
Qts; 0.43
Vas: 13.7L
The Crossover
I started off with a 2nd-order crossover, enamored with my success on the
Model 1. Like the Model 1, forcing these drivers into
a reasonably smooth 2nd-order response required a complex crossover.
Unlike the Model 1, it never really smoothed out, and still retained
a slightly "plastic" sound that you get from most mid/woofs under $50. Second-order
really was too much expense to consider for this woofer, and didn't sound better than
4th-order.
The current crossover is a 4th-order LW at 3,500Hz. I couldn't resist using as much of the M130's range as possible, and the 8513 prefers to be crossed above 3kHz anyway.
As you can see, I've used a trap on the low-pass. It is completely optional, and removing it will not have any global effects. It is used to knock down a hump at about 800Hz. If you can't hear this hump, then don't worry about using the trap. I'm listening without the trap right now, and don't hear anything that bothers me.
The high-pass is about as boring as they come.
The current crossover is a 4th-order LW at 3,500Hz. I couldn't resist using as much of the M130's range as possible, and the 8513 prefers to be crossed above 3kHz anyway.
As you can see, I've used a trap on the low-pass. It is completely optional, and removing it will not have any global effects. It is used to knock down a hump at about 800Hz. If you can't hear this hump, then don't worry about using the trap. I'm listening without the trap right now, and don't hear anything that bothers me.
The high-pass is about as boring as they come.
Results
For a budget speaker (under $250), this one is pretty good. The 8513 tweeter is
a bit much, and the design would probably be better served with one of the many excellent $30 tweeters on the market.
Unfortunately, I don't have any of those laying around, but I am supposed to get one of the new Seas fabric domes
soon.
I would like to compare this one directly with Dennis Murphy's M130/Hiquphon two-way, to see if he got better sound from the woofer than I did. Unfortunately, I don't have any OWI's laying around, either.
The only thing I don't like about this speaker is a slight lack of refinement in the midrange. On its own, it sounds quite good, but a comparison with several of the $75 to $100 mid-woofs on the market would show it lacking.
Here is the response, on-axis, gated far-field merged with near-field woofer response (sealed box), smoothed 1/6 octave, with the woofer trap connected. It shows reasonably flat frequency response, about 4dB of baffle-step correction, and an F3 point in the mid-80's. It should be used with a subwoofer, and placed maybe 2-3 feet from the nearest wall.
The reverse-null is shown smoothed 1/12 octave. The null is reasonably deep, but not very wide, showing good phase matching, but not over a wide frequency range. It could be better, but it's nothing to be ashamed of.
I would like to compare this one directly with Dennis Murphy's M130/Hiquphon two-way, to see if he got better sound from the woofer than I did. Unfortunately, I don't have any OWI's laying around, either.
The only thing I don't like about this speaker is a slight lack of refinement in the midrange. On its own, it sounds quite good, but a comparison with several of the $75 to $100 mid-woofs on the market would show it lacking.
Here is the response, on-axis, gated far-field merged with near-field woofer response (sealed box), smoothed 1/6 octave, with the woofer trap connected. It shows reasonably flat frequency response, about 4dB of baffle-step correction, and an F3 point in the mid-80's. It should be used with a subwoofer, and placed maybe 2-3 feet from the nearest wall.
The reverse-null is shown smoothed 1/12 octave. The null is reasonably deep, but not very wide, showing good phase matching, but not over a wide frequency range. It could be better, but it's nothing to be ashamed of.