passive radiator for 40-1197?

[transaluminum]

suppose you have a pair of Fostex 103's or RS 40-1197s

you are supposed to put these in a horn loaded enclosure

or a bass reflex design, correct?

What about a 16" X 6" X 8" box with a small passive radiator?

Madisound has a 5 1/4 in Passive for 15$ each

any comments?...thanks

[GM]

Well, if I had to 'suppose', I'd suppose it should be in a small sealed cab like originally intended several decades ago (at least that's my dim memory), but it's rarely used that way these days.

Anyway, per Tom Danley we want a PR that has ~1.5 - 2x the displacement as the 1197, so at nearly 2x, this PR is plenty big enough, but this box alignment only needs a ~4.4 g Mms, so at 48 grams, it's way too heavy. This PR requires an equivalent vent length of nearly 180".

GM

[TerryO]

Originally posted by GM
Well, if I had to 'suppose', I'd suppose it should be in a small sealed cab like originally intended several decades ago (at least that's my dim memory), but it's rarely used that way these days.

Anyway, per Tom Danley we want a PR that has ~1.5 - 2x the displacement as the 1197, so at nearly 2x, this PR is plenty big enough, but this box alignment only needs a ~4.4 g Mms, so at 48 grams, it's way too heavy. This PR requires an equivalent vent length of nearly 180".

GM

GM, With a vent that long it's almost possible for you to listen to his speaker at your house in Georgia, if the vent was external.


My pair of Hi-Tweek Black Box Nearfield Monitors use Modified RS 40-1197 drivers in a vented box that is tuned to 65 Hz. However, they are very purpose specific and I wouldn't recommend it for normal use. They were intended for nearfield use and can sound congested (constipated?) at levels necessary to fill a moderately large or even a normal sized room.

Tuned higher, they can certainly be used in a vented or BLH solution.

Best Regards,
TerryO

[GM]

Greets!

Yeah, with a ~18.8 Hz 1/4 WL it would carry a long way.

Yeah, little drivers and big rooms don't match up too well, though I was surprised at how well the little folded, bottom vented ML-Voigt horns I made for Dave's tweaked 1197s filled a fairly large, though reflective, hotel conference room semi-full of folks at one of the Atlanta DIY Meets. IIRC they were tuned in the 60s and driven with a restored Marantz tube integrated map? receiver? through either an 8 or 10 ohm series resistor. Memory's pretty much MIA these days.

They were very lush sounding, handling a variety music from Alison Kraus to Dave Brubeck with equal aplomb. Dave's coating and phase plug and ? really smoothed them out. Anyway, this is the cab: http://www.planet10-hifi.com/boxes-fostex.html#GM-mlv

Happy 4th and all that jive!

GM