3-way Seas design

Hello,

I am designing a pair of floorstanding speakers for a friend of mine and he has given me a budget of $1000 before cabinets. I have contemplated a few designs and think that the following 3 way design could be very solid. I had originally thought of a MTM design consisting of the Vifa XT25 tweeter, and either 2 Vifa XT18's or 2 Extremis 6.8's.

The 3-way seas design is as follows:
Woofer: L26
Midrange: MCA12
Tweeter: 27TBC

I have always worked with 2-way designs before and was a little scared about the complex crossover required for this system. I have come up with crossover frequencies of 700Hz and 3500Hz, all 2nd order and impedance compensation (zobel) on the woofer and midrange. The tweeter is then attenuated to match sensitivities.

According to my simulation software, the -3dB point when using the L26 is 31Hz in a 2ft^3 box. What I am concerned about is the crossover. I don't want there to be distortion because I am forcing the speakers to play frequencies they can't handle.

It would be very helpful to me for someone to comment on this design as I am sure there are many members here that have experience with the Seas drivers.

THANKS
 

Taco

Member
2002-11-06 11:32 am
lowlands
There are a lot of options about which drivers to use, but I see no problems. I never used those drivers, so I cannot comment if the match is alright. But you cannot go wrong with Seas. I have made a 2-way using the 27TDC and 18cm paper woofer from Seas.

I have only one suggestion, try to cross the L26 @400Hz to the midrange. You want to cross the L26 as low as possible to avoid energy storage in the aluminium cone.

Maybe you can also look at the Dayton RS180 combined with 27TDFC / 27TBFC and those new 12" Dayton drivers. Or those new Peerless Exclusive 5" or ...
 
Thanks for your replies. I think that in order to cross the L26 at anything lower than 500Hz I may need to pick a different midrange. I want to order all the parts from Solen so the Dayton driver is out of the question, but maybe peerless. I had wanted to use the MCA15 instead of the MCA12; Solen has it on their site, but I cannot find it in the price list.

I guess I have some more experimenting to do.
 
DcibeL said:
Hello,

I am designing a pair of floorstanding speakers for a friend of mine and he has given me a budget of $1000 before cabinets. I have contemplated a few designs and think that the following 3 way design could be very solid. I had originally thought of a MTM design consisting of the Vifa XT25 tweeter, and either 2 Vifa XT18's or 2 Extremis 6.8's.
THANKS



a bit out of context , but for $599 US, .. RAW acoustics has a 3 way kit using a single extremis , wr125s widerange, ribbon tweeter, x-over etc http://quicksitebuilder.cnet.com/wrnch2/rawhtserieskits.html . i'm in the process of helping a friend build one of these so can't report on performance yet, but thought it might be inline with what you're going for.
 
I think that if I lower the low crossover to say 500Hz, and insead of the MCA12 I'll use the L12 for the midrange it should be a very nice speaker. The L12 will also keep the speakers aesthetically pleasing because now the drivers will match :). I'll just have to make sure that the resonant peaks are taken care of in the crossover.

I will be talking to my friend on the weekend and we'll see what he thinks of this.
 
So my final design now uses the L26, the L12, and the 27TBC. Crossover points are 600Hz and 2500Hz, all 2nd order except the lowpass on the L26 is 3rd order. The only thing I don't like about the L12 is the frequency response starts to roll off at 1000Hz so there is a will be a slight dip in the frequency response when using this driver.

Thanks guys for your help.
 
It looks as though I am sticking with the original plan stated in post #10. The midrange and tweeter will be sealed in .238 ft^3, and the bass driver will work inside of 2.275ft^3 tuned to 25Hz. In this configuration, the driver will keep below xmax up to 85Watts input. At this 85Watts input, 108dB of output is available at 1m (simulated).

Thanks all for your help, it is much appreciated.