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Why so few speakers with Passive Radiators?

Folks,

What are your thoughts on Passive Radiators in speaker design?

I've had many different speakers (and like many here, have heard countless varieties outside my home), from ported, to sealed, to passive radiator, to transmission line.

In my experience by far the best bass has come from the Thiels I've owned - CS6, 3.7, 2.7 which use passive radiators.  The bass in these designs are punchy yet as tonally controlled, or more, than any other speaker design I've heard.  So I figure the choice of a passive radiator must be involved somehow, and it makes me wonder why more speaker designers don't use this method.  It seems to give some of both worlds: extended bass, no port noise, tonally correct.

And yet, it seems a relatively rare design choice for speaker manufacturers.

Thoughts?
prof
robinbarbour
66 posts
 
Tom,
I got lost with sealed box and transmission line. How do you have both? Aren't all transmission lines open box? 
robinbarbour
66 posts
 
Do you mean a sealed box, equalized within a transmission line? I guess that would make sense?
This would be only for the very, very low frequencies I assume.
I have always liked transmission line bass. Very relaxed and effortless.
goledeniers's avatar
goledeniers
1 posts
 
I have had virtually every flavor on the market, since 1956. Planar, electrostatic, loaded, ported, open air. It is my feeling that, while the loaded are power shy I find the ported boxes offer some Chuffing. I find this disconcerting. Currently I am happy with the 3 individual enclosures per side, 2-6 inch Scan speaks per box, for a total of 6 small woofers per side to be quite rewarding. Quick, powerful,authoritative and natural. No lumbering giant cone, no vent. I may stay with this configuration forever.
kensw
8 posts
 
Speaking of the east coast sound pat5jfet referred to, I have a pair of EPI 200C's I picked up for cheap a few years ago from the original owner that bought them in the 70's, like new grills and cabinets. I can't remember the details of the history, but I recall Genesis factored into the lineage somewhere. A fellow named Huh Powell was once associated with one or both of the companies and still provides parts and service for the brands in New Hampshire. I bought updated jack panels/crossover caps for the 200C's couple years ago. With a big passive radiator, 12" IIRC, and the inverted dome tweeter they are very nice sounding and doing active duty in my third system now.
10000_hz_legend
72 posts
 
OP,

I agree, it seems like a very good way to deal with the air, but sometimes it makes no sense to me.

The KEF Q series floorstanders for instance seem to me to be a complete engineering disaster.  You have two chambers, one on top that holds the uni-q array (tweeter and midrange) and one passive radiator, then the bottom chamber holds an active woofer and passive radiator.

SO..  When the active woofer is moving OUTWARD the passive radiator is moving INWARD.  180 Degress out of phase.  How can you deliver a clean wave to your listener when BOTH the top and bottom passive radiators are 180 degrees out of phase??? They should have been place on the back, or bottom IMO.
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