Room coupled loudspeakers?

[suprf1y]

I really like this board. Moderating the new posts is a good idea. I guess it frustrates the spammers.
As I've said before, I'm just getting back into the hobby, and have some questions. Before the internet, my only source of speaker info was speaker builder magazine, and I built lots of projects based on things I saw, and read in the magazine.
I remember building something called a 'room coupled' loudspeaker. They had top firing woofers, and were placed right against the wall. As I recall, I really liked the sound. Does anybody still do this, or were these just a bad idea? Would it make sense to try and build a TL variation of this?

[suprf1y]

Nobody?
I thought they sounded good

[rick57]

Not exactly sure that 'room coupled' is a specific style of box building. If a tweeter or mid were to fire up, it might be called omni-directional. In some Shanihinan speakers, tweeters mids &/ or bass fire up at about 30 degrees, to bounce off the wall and create a more spacious sound, at the cost of imaging.

Was it Lyn Olson (amongst others) who advocated having bass drivers in an otherwise normal vertical position, very close to the floor, to assist room gain.
Firing *up would assist room gain less, due to distance from drivers to ceiling.

Was the wall behind the speakers hard, eg concrete, so that it absorbned less sound and reflected more?

[Brett]

Originally posted by rick57
Was it Lyn Olson (amongst others) who advocated having bass drivers in an otherwise normal vertical position, very close to the floor, to assist room gain.

Originally it was Roy Allison.

[suprf1y]

Was the wall behind the speakers hard, eg concrete, so that it absorbned less sound and reflected more?

I think that was the idea. I looked in some of my back issues, but the only thing I could find was something similar by RDL acoustics called 'room designed', whatever that means.
I remember building them one weekend as a filler project when I had nothing else going on, and recall that they did sound pretty good.
I just wondered if a TL version might sound even better?

[rick57]

TLs go deep (or is it rolloff slowly?) but are probably the hardest to get right.

Search here on them, look at Planet 10's TL site, and/ or get a copy of Dickason’s Loudspeaker Cookbook.

[suprf1y]

I found a project in one the back issues, and it was Roy Allison's design ideas that they were trying to copy.
These aren't the ones, but they looked like this.

[rick57]

A six inch won’t have much output sideways. I would guess that such a layout would loss output from maybe 300-500 Hz up to the tweeter crossing in, maybe at 2500 Hz. You don’t mind that?
I suggest you read up on the beaming of drivers, based on driver size & frequency.

[Brett]

Originally posted by rick57
A six inch won’t have much output sideways. I would guess that such a layout would loss output from maybe 300-500 Hz up to the tweeter crossing in, maybe at 2500 Hz. You don’t mind that?
I suggest you read up on the beaming of drivers, based on driver size & frequency.

Or you could simply put another midbass on the front too, like Castle do.

[BillFitzmaurice]

You might want to look at the David speaker at my site. The woofer is a folded horn with the exit at the bottom of the box, and altering the position relative to the rear and side walls allows adjustment of the output from 20 to 120 Hz.