Cabinet Size of Satelites ???

[ralph-bway]

Hi all,

Before I do something stupid I wanted to ask a general question about cabinet size.

I'd like to turn full range two way polks into satelites (they're the old M10s, I like the way they sound, and they were reconed 3 years ago). I like the bass on these speakers they're very tight and crisp.

Using WinISD the dual polk 6.5's need 3 cubic feet of volume in a vented cabinet to be flat to 35 hz. I'm going to be using an electronic crossover at 250hz to two subs (right & left).

From WinISD I can get a flat response to about 150hz with the polks in a closed cabinet of .8 cubic feet.

My question is would such a dramatic reduction in cabinet volume have an adverse effect on the drivers since there would seem to be much more back pressure on the drivers from the much smaller cabinet volume? Would using a 10" or two 10" passive radiators per cabinet help this?

These speakers would become the front mains for HT, and eventually I'd like to use electrostatics as the mains for serious listening.

Thanks for any help & suggestions.

[ashok]

IMO a sealed box would be good if you can go down as low as 100Hz or so. If not , a reflex box might be better. Crossing over as low as possible is good. 100Hz or lower is good. Above 100Hz we slowly get into the lowest voice territory and that can cause problems. I think that is around 150 Hz or higher.
With a sealed box you will get a -12db/octave roll off and you can use an electronic -12db /octave filter to give a 4th order Linkwitz Riley rolloff.
Try to get a Q of 0.707 in a sealed box and make an electronic crossover with the same Q and Fc.
For a 4th order LR filter 150 Hz may be Ok because it is -6db down at 150Hz and rolls off at -24 db / octave .
Avoid passive radiators - you seem to like tight bass and passive radiators (IMO) are better at LF extension at the expense of tight bass. If any units can get tight bass with passive radiators , it must be quite hard to achieve this.
Satellites need not have any drivers bigger than 5 or 6 inches to sound great ( and loud) with a supporting sub ( preferably 12 inch ). Don't worry about back pressure , just follow what the simulation shows.
Cheers.

[navin]

if you are using 2 subs and the subs are next to teh full rnage (200Hz+) system and your listening distance is not near field yuo can get by with a 200hz XO point however when you have a single sub or the sub is far away from the main speakers use as low a XO as possible.

still i think ashok is correct. 100Hz is really ann you need. the M10 should be able to handle prodigious power above 100Hz so why compromise.

how do you intend to seal the M10 box? i would try a aperiodic vent by stuffing teh vent with open cell foam. and see how it sounds. you can always seal the port by stuffing it further.

I use JBL Pro III (control1) for my rears in most cases it is fine. good 5-6" are adequate for most purposes.