Superfly beat me to the punch. Both my parents had IMF speakers (TLS-80s and 50s) in the eighties (the 50's were handed down to me).

Here is a useful link describing TL speakers

Transmission Line Speakers

This might answer the very first question "How can you get as much bass out of a 6 inch vs a 12 inch or can you?"

AK

In the auto world is a saying, 'ain't no replacment for displacement'.
Kinda' applies here I believe.
Good things can be done with smaller drivers but they are the exception.
I had a set of Klipsch KG4's that could put out impressive bass for their size.
They had a passive radiator in the rear and required proper placement to bring out the bass.

I have always found older transmission line designs bass to be undeniably deep, but slow and rather detached.

In a true transmission line all the rear firing energy from the driver is completely absorbed in the line, but most hifi designs release the rear wave into the room via a vent and are better described as: 'Folded & damped <quarter>, <half> or <full length> lines' (depending on the line length). Maybe that’s why they sound a bit sluggish to my ear.

The key point is that while you can get away with a smaller woofer it still takes a big 'ol TL cabinet to get deep bass. If I am going to be stuck with a big cab anyway, I might as well have a chunky infinite baffle or ported cab with a large woofer and enjoy fast, detailed and tactile bass.

One more point: Its important to keep in mind that the KEF B139 'Racetrack' driver has a radiating area of 55 square inches (about the same as an 8" driver) and a decent quarter inch throw, so its not really a 'small' woofer!

Now having said all that, I have to admit that some modern Transmission (quarter wave?) lines from companies like PMC do sound a lot faster, but tellingly the smaller models don't really seem to go all that low...

As far as an object lesson, last night I listened to a Randy Newman album, with the song "Master Man & Baby J", a sendup of Rap Fame.

I listened to it last night on Polk RTA-8tLs with a 6-inch woofer, and said, "This sounds really good."

I'm listening to it now on Polk Monitor 7s, with a 10-inch woofer, and saying, "Wow!.

I decided to upgrade the system I'm giving my son with the Polk RTAs,
rather than wasting his time with the Sansuis and lesser ARs I had set out.

He's old enough to get it.

And I have the Klipsch KG-3.5s on my bedroom system right now.
I like them with most music, love them with some music,
and won't be parting with them any time soon. There is very
little cone in those big towers for the amount of defined sound that comes out.

my epo 12.2 have a lot of body for a bookshelf. all my friends love them better than my 16s. if i had to suggest a speaker for a small room they would be it.

but aren't we forgetting what you put into the speaker determines in the end the sound that comes out. let's just say crap in crap out.

I know it's old hat, but "playing" (and I use the term literally),
with placement, yields some surprising results. I gave my son
a pair of yamaha 3way bookshelves years ago, and he eventually
trashed them. I picked up another pair, in good condition, and they've
been sitting for a while. i hooked them up on top of the pile of speakers in my
living room, consistent with a high bookshelf, and while they didn't compare
with the Polk Monitor 7s I followed them with, they were a lot more good than
bad, and told the story of the music, if not with every nuance.
Sitting on the floor, I doubt they would have had much to say.

"Crap in, crap out" can apply to anything in the audio path and that includes the recording, source, preamp, amp, and as we are discussing here, speakers. So, it is not as simple as selecting the best reviewed speaker money can buy.

I'm in the process of auditing my signal path. I am lucky enough to have a local tech who will perform the square wave -*test*-('") on my gear including amps, preamps, and CD players. If any of these devices cannot reproduce waves accurately, the sound at the speakers will be compromised.

So far, my amp choice is settled. Now I have to locate a preamp and CD player that perform as well, if not better than the amp. My tech has a CD with square waves recorded so he can scope the CDP output! I was also very surprised to see how CDP's and even preamps can compromise the wave form.

I'm not sure if there is a way to measure actual sound waves at the speaker, but I'm sure it can be done.

a lot of people talk about synergy. all i know is what sounds good to me. you see what i said to me. we all have different taste. i like a pretty equal sound. i don't want anything coloring the music. i like it raw i guess you could say. i like old hafler and i do like the sound of tubes. but then i like my creek components also. i'm not a big bose or sansui fan.
when i build speakers i always went 1st order. just as simple as you can get.
you talk about components but you have other factors involved cables, ac filters. there is so much to think about. your power cords, the kind of music you listen to.
we have had all this talk about speakers. don't get me wrong i have enjoyed it. i have learned things and that is why i come here.
in this group i have learned it doesn't matter if you have a 10,000.00 system or a 500.00 one. if you like it thats all that matters.
pay me no never mind. i'm on my meds right now and should be asleep; but here i am typing.
i hope this thread continues. we haven't talked of spl or if they are true. we haven't talked about venting or the design of the box. what to use to build the box. how about concrete?

spl is measured 1 watt- 1 meter. if you have a vom and a sound meter you can measure spl. i could be wrond but a voltage of 2.86 volts equals a watt. do co.s fudge this ? i thing so.
now with xovers. do you like computer built or doing it by ear and doing your own formula?

Thanks for the links - interesting stuff.

First off, damn handsome loudspeakers! It seems Legacy use various bass loading strategies. Some models seem to depend on the tried and -*test*-('")ed 'several big drivers working well within their envelope' paradigm. Nothing wrong with that, it should give a natural, extended and low distortion bass response. But I thought the ABR system with 'Dynamic Braking' was especially interesting:

"I have called the down-firing driver a ‘passive radiator’ it isn’t really. It has an identical voice-coil and magnet system to the other two bass drivers. However, in a rather curious design arrangement, Dudleston uses the coil/magnet system in reverse, so that the motion of the cone that’s induced by the air movement inside the cabinet caused by the other two drivers not only generates sound on the ‘outside’ of the cone but also energises the coil, generating back-emf. However, this back-emf is fed straight back into the driver (by means of being ‘shorted’ on the crossover PCB). This means that the faster the cone moves, the ‘stiffer’ the cone becomes, the end result being that it ends up dynamically limiting the cone excursion of the main two bass drivers by reducing the volume of air behind them."

Clever. Very clever...

I would love to hear them but I'm pretty sure they don't have a distributor in the UK. And even if they did, I'm absolutely sure I couldn't afford them!

I got my Classics at a greatly reduced amount due to the previous owner getting water marks on the cabinets and nobody wanted to pay what they would be worth, I put smoked plate glass on top of the speakers and nobody sees the damage which is only to the looks anyway.

A year ago I found a pair of Signiture III's, someone had replace some of the drivers with the wrong speakers and messed up the crossovers, I had even gone so far as to contact Legacy' they still had the proper drivers and indicated that if I were to get them that the crossovers would also need to be retuned and that I could bring them out and they would take care of that. Unfortunately for me the owner decided he was going to try to repair them himself, I don't know if he ever got them back to right or not.

Jim

Back in the 70's when the watt wars were going strong a lot of the mfgrs. jumped on the band wagon of inflated ratings. RMS watts are the standard which the reputable mfgrs. go by then and now.

Here is a very good article with illustrations that explains RMS & IPP. Well worth the read.

http://www.barrys8trackrepair.com/AudioFax.html

good article. taught me some things.
larry

From ST Links Topics an interesting software i think you guys would like to experiment.

http://www.libinst.com/Audio%20DiffMaker.htm