Ahaa! I can see your talented mind is at work again! Is this something you're contemplating designing and building? Something like the powered Von Schweikert DB99 or passive NHT 3.3?
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I have the PD80's with the amps. The problem I had was a lack of knowledge. I had them a little loud at first and the placement was all wrong. It took some playing around, but I've pretty much got them set up now so that they don't sound like subs at all. Also they are quite efficient, so really low volume listening is surprisingly good. I'm happy.
Not being sure what specific info you'd like, here are random thoughts fm using such configs, commercial and diy**
Generally speaking: F-Response and energy and power response are better than their fully passive counterparts (OK, design permitting of course).
*1st: as you note, I too refer to BASS frequencies -- not low/sub bass -- see below, "caution".
*Having variable phase control is a useful feature.
*No issue "marrying" the top & bottom amps' amplitude or coexistence;
Caution: There IS an issue marrying sensitivity b/ween the two parts and more importantly, linearising the spl downward (in frequency) -- which in turn means yr woofs' excursion can hit the roof (or the opposite wall as it were). Say you cross @~80-90 Hz (a nice setting) you'll be hitting overwhelming energy at xover and whispering two octaves later. Woofs with high nominal sensitivity )at least) are necessary; OTOH, will you critically damp or underdamp?? to get those 20Hz at say -6dB...etc. I'm sure yuo know this better than me.
However this is tricky and none of the commercial spkrs I've used are very easy to dial in (example, Gen uses servo).
Apart from the above little detail one has to address & the fact that you have to dial in an extra active channel per side when gauging the distance between the two speakers in room placement (the midbass -- i.e. the crossing b/ween top & bottom part -- is difficult to get right so as to achieve the stereo image AND energy), things are OK.
Is there s/thing else you might be interested in (& I might know:))?
**I have used Genesis models (particularly the Vs & 301) and A-P Medea (the model with Manger drivers). The AP had an integrated amp on each side while the Gens had it separate. The Gen Vs' woofs are in same polarity front & back. The others had side firing woofs (same polarity).
I have also lived with diy, Lowther top & separately amplified bass (2-way) where, again, the FR units were sitting on top of the bass.
Thanks for your responses. I appreciate each of you taking the time.
Gregm, thanks for mentioning the AP Medea speakers - I wasn't aware of them. Perhaps along vaguely similar lines to your DIY project, I think Carfae made a Lowther-based speaker called the "Little Big Horn" that had a built-in powered box woofer section.
Gunbei thanks for the vote of confidence but I'm not really talented; just a smooth talker is all. Good guess on my plans though - I'll shoot you an e-mail.
I currently have def tech 7002 w powered subs along with 2 def tech super cube II's. The biggest problem i had in the beginning was getting the internal subs to blend with the super cubes II. There is a phase control on the super cubes but was still tricky. Given the cost for my entire speaker set up( 7.1 ht approx 5k) I am blown away by the soundstage that i now have. I am aware they aren't considered audiophile speakers, but if someone wants to get into hometheater ( myself 80% ht 20% music) these are a no lose purchase. I am lucky enough to have a wife who allowed me to use our finished basement for a dedicated ht set up. I will actually go out on the limb and challenge anyone to compare "cost to overall sound" and see if they can come close. I think the internal subs in the def techs are what makes them the "home theater speaker deal of the century"....Just my 2 cents...