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TL vs Overdamped BR - Opinions?

The theory of the designs are explained. How to design a t-line was never explained The answers are given in the enclosures. Break everything down mathematically. Find the common denominators. The answers are there it comes down to asking the right questions. What is the cutoff frequency for each of the t-line enclosures. What is the volume of the enclosure after subtracting the wood used to make the lines. What is the line length in each enclosure. The taper ratios are self explanatory for each enclosure.
 
My comment is regarding this concept of an "expanding sound source". I don't believe it to be a technical term or concept used in industry, rather a marketing term used by Fried.
 
You have to look at at the enclosures 3 dimensionally. Figure out the volume of stuffing in each section of the line relative to the volume of each section of the line. It is very time consuming. How were 3 different drivers used in the same exact O lines that had different driver specs ?. The stuffing density was changed for each driver. I discovered this by comparing the plans I have aquired over the years.
 
Other companies have done this. Look at IPL, TDL enclosures . I agree with the marketing hype. What do low frequencies do that exit line terminus. Look how long a 22hz wavelength is. They expand due to their size. That is why you need a large listening area to fully appreciate the sound. You can hear the bass better ouside my house then inside when I have them cranked up.
 
@sm19422:_______________________________________________________
"You can hear the bass better ouside my house then inside when I have them cranked up."
*
Oh, I bet your neighbors just LOVE you. :lmao:
Actually I understand that explanation perfectly.
Not sure what that says about me.

Sure wish I had a truckload of good TL cabs to disassemble for a
Chinese blueprint. :D Oh well, guess I'll just have to keep studying
the subject and maybe even actually download some software.:yikes:
 
sm, I don't think your son is going to see a lot of TL cabs in pro use any
time soon. Actually there is one company making inroads there, but as far
as I know, so far their stuff is more for control room monitors and such.
In big venues it's still lots of horns, going for both the efficiency and tightly controlled
throw pattern and throw distance, which can be tailored for any given venue.
You should see the size of a big 'W' cab folded horn for twin 18's.
Don't even get me started on the line arrays.

I can see using pro drivers in TL cabs, if the parameters match the application.
The stuff is well-made enough, and it sure is nice to be able to get a re-cone
kit for a 40 year-old driver. Customer support is generally phenomenal. I've
done many a DIY project with raw drivers from JBL's Pro Line. Sometimes
for home or control-room, mixed & matched with stuff from Speakerlab
before they went all yuppie. (Might sound weird, but it worked.) You get the
driver, and exact instructions on just how to build your cabinet - they did all
the science for you. Boy you get spoiled. That's how I made it all this time
without having 2 cents' worth of comprehension of T&S parameters. Now
I've gotta REALLY catch up. I've yet to register with the Yahoo group, but
given another day or two I will make good use of that link.

I agree that DIY'ing the cabs is nice in that you've got all that freedom to
get creative with the wood. Particle board per se deadens better than
MDF, MDF shapes nicer, Baltic is strongest... There's so many ways to
combine & laminate, layer in deadening compounds and on & on.
 
I have a Christmas tree farm. The neighbors don't have an issue with the speakers. They have issues with other things. I border a state park and have gotten involved with the appropriate state agencies over wildlife management. They have issues over the use of firearms and noisemaking devices in the wildlife management of deer for crop damage. It's a long story. I am under constant watch for deer engaging in crop damage . I have lights out in the fields with about 700 feet of extension cords. About the only time deer come onto the property is after dark.

http://www.opticsplanet.net/streaml...shlight.html?gclid=CNK0ru-WkK4CFULc4AodNggdqQ



http://www.remington.com/products/firearms/shotguns/model-870/model-870-express-synthetic-deer.aspx
 
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hannibal said:
Hey 'Mojo,
I see I could in fact have phrased myself better.
But it's good to have that 5 cubes for a design basis if I do decide to
go conventional BR.

"You may able to get by with just the two drivers-similiar to the tower.
Idealy the Great Heil works best with a transition driver, but the smaller
woofer would minimize problems."
*
Dave Dlugos AKA Planet 10, often to be seen at DIYA, did something like
that with a pair of 9" Fostex, push-push, in a TL that looks an awful lot like an
AMT 3 Tower clone. He said he liked it better than an AMT 1 he'd
shoehorned an Eminence Alpha 6A (IIRC) into, so yeah it can be done.
Fostex seems to have followers that see them as really fast. I looked at
a bunch of them and kept seeing some pretty heavy Mms on them. That's
another thing that has me wondering what I might still need to learn
in evaluating the speed of a driver via it's T&S parameters.
Myself, I don't want to go to all the trouble of building a TL (or any) cab
with an undersized driver and then STILL have to bring a sub to the poker game.
Odds are I'm going to go 3-way no matter what. Not necessarily,
but odds are.
Click to expand...

Fostex makes good drivers, and when properly implemented will sound great.
Large Xmax is great to have in any woofer IMHO, but is really only need in sealed enclosures-as BR and other types of ported enclosures require less movement of the woofer to produce sound, particuliarly at the port/opening tuning point, where the driver moves very little and the port/opening does most of the work-thus the increase in efficiency, and output (3-4db) as well.
With the 2 pairs of AMT3's I have, I am working with certain constraints, as I'm not going to change the dimensions of the cabinet. All my modifications will leave the box essentially stock.
As mentioned, the AMT3 was originally intented as a sealed enclosure, and was only later ported to increase the bass output. Running a quick ISD show that most 10" woofers made for sealed, or sealed/ported enclosure running in pairs hover around the actual inner volume (2.5-7) of the stock AMT3 cabinet
The O.E. Alnico woofers are great in their own right, but if ESS had the 1040SF's to work with at the time, I bet they would have left the cabinet sealed. The 1040SF's provide plenty of output sealed and still beat the O.E.'s in output in the vented state.
The closest I could have gotten to a ideal ported state with the 1040SF's in the stock AMT3 cabinet would have had 2x 4inch ports at around 6" long.
I wasn't going that route, as you really would have had to use a thicker baffle with those large holes. Plus my cabinets are darn near mint. In fact they were both all original 1 owner speakers.
The nice thing, among other things with using a sealed cabinet is that they are very forgiving when you are around their ideal cabinet volume. The all you are dealing with is the amount of damping you want to get the sound/response you are looking for.
The added bonus is that this works great in the AMT3 setup, as that was what the AMT3 was orignally designed around anyway-a sealed bass enclosure.
Having 2 vs one woofer makes it work, it's not your average one woofer sealed/low efficiency setup. The 1040's makes a ideal candidate IMHO because it has everything you are looking for in a driver that can keep up with the Heil. Most of the other woofers I came up with were lacking in one area or another, and not as versatile.
The Dayton Series II 10" woofer was my other choice, it to is a jack of all trades speaker like the 1040, but it's sealed performance rolls off a little too soon. It's a heavy beast as well, and would need baffle bracing manditory-something I wasn't sure if I wanted to deal with early on.
I had a few conversation with Rick @ OCS, and did some other foot work before I decided it was the best compromise for my setup.
The bass is different from a TL design in that it occupies mainly the listening space and a few closer rooms (perhaps the pressurization effect) but doesn't get boomy, or eminate outside. You can also feel it in your feet/body, but it's not the type that gives you a headache or fatigue.
Bass quality and quantity are a taste issue-some people still don't like much bass, as they consider it a type of 'distortion' for what ever reason. Personally I just like mine tight sounding, deep and detailed, with a clean midbass, and I'm a happy camper. Efficinecy, as with any speaker IMHO is helpful as well.
The mids and highs, and their imaging and floating quality, such as the Heils have, I'm perhaps more picky on. But the speaker drivers has to work as a whole, not dominate one region or the other. To me that's more important then one extreme or the other. And that's the beauty of the sealed 1040's in the stock AMT cabinet- they all work beautifully together-and that was my main objective. To get just a bit more bass output and detail without ruining the voicing or balance of the original AMT3 setup.
Perhaps I lucked out-but it works well regardless.
It would be interesting if you could run a TL AMT3 clone that had enough space to squeeze in a sealed mid chamber and not take up too much space.
I'm sure it's doable with a little work.
 
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Huh, maybe you could use your subs to scare away the deer,
collect a little money from the state while you're at it.
Sorry, I couldn't resist. :D
 
How much this adds to the discussion, or not, I don't know, but I can post my own personal listening experiences with two vintage designs here, one a passive radiator design with two 6.5" woofs per cab, and one a TL design with two 6.5" woofs per cab. Both of these speakers are decently respected here, however in my listening experience, the TL musicaly and in correct timbre beats the "PR" design hands down.
 
@automojo:_____________________________________________________
"It would be interesting if you could run a TL AMT3 clone that had enough space
to squeeze in a sealed mid chamber and not take up too much space."
*
Or if that's too much like work, I could always put the mid in a nice little sub-
enclosure and park it on top of the Heil. Maybe still use a tube about the
size of that in the AMT 3, then that into a pretty wood box... Maybe fill the
void between the inside box walls and the the tube OD with duct clay or
sand. Obviously the rear of the box would need legs or something, but that's
no big. Dowels or stainless tubing would hold it up fine and not block or diffract the backside
sound from the Heil. Then the main thing is to figure out how best to stuff the tube inside to
deaden the mid's back wave as much as possible. Just one possibility of many. It occurred to
me that having the Heil actually between the mid and the woofers might make it sound a
little more point-source like. If so, better yet.
 
Hey Dave.
I'm the OP, and that is much of what I'm looking for. Subjective experiences
based on comparative listening. Thank you much, it's good stuff.
 
Just make a box to the correct volume ans stuff it, full but not tight, Eminece should have the specs on this.
As a side note, some have commented to me they don't like the foam surrounds on the 1040's, as they think it's cheap. Actually the cost are close to rubber, and foam is actually stiffer then a lot of rubber surrounds when it comes to properly locating the driver in a 'piston' motion, and still provides adequate damping.
It does need to be replaced over time-but the new surrounds are much more durable then the ones 20 years ago. The nice thing about Eminence is that they always have NOS, and you could just recone them for $30 more each and have a new driver every 10 years or so.
Personally I don't worry to much about that, as it's just maintence to me-no big deal. 10 years is a long time-might not be around then, and I'd rather enjoy good sound now then worry about the future of my drivers.
I agree on the PR comment. PR speakers can sound good, but it seems like most, at certain frequencies and tones, become one note wonders. Expensive designs don't do this as much, or at all, but they still usually have the same quality of bass, lacking some detail and musicality, until you move into the upper price regions.
Sealed designs may have some distortions as well, but they can be minimized, and their added detail and musicality, and more 'accurate' dynamics is worth the trade off IMHO when working with certain cost or design constraints.
 
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I dont't know if I should be on an audio forum or hunting forum. Anyone in Montgomery County PA that wants to go deer hunting contact me. We are 25 miles northwest of Philadelphia in a county of .75 million people with issues. That's why I took pictures of the speakers during the daylight so the trees could be seen in the background.
 
The Bose Waveguide Radio being a waveguide is technically a t-line right ? Some of the paper surrounds look foam laminated or foam impregnated paper surrounds Automojo. Foam surrounds have come a long way have not they. I prefer pvc or butyl rubber surrounds but if the price is right. That is why I bought overstocks of Bose drivers from Martin Sound to experiment with in the late 90's to compare different types of cabinet loading techniques. Prices from 3.95 for woofers and cube drivers to a quarter for the model 201 tweeters to experiment with in t-lines and series circuits. Madisound had one of the first high reviews for foam rubber surrounds by Gary Galo in Speaker Builder in 1981. .
 
Why can't Eminence or another USA company design and market a tweeter comparable to the ones made in Denmark? I would be happy if one made in Mexico, Braszil, Canada, Venezuela or Cuba rivaled Denmarks best at a significantly lower price for the use in one of my t-lines. Series crossovers would also be a nice topic to discuss.
 
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Hi,

FWIW I understand the AMT 3 with the AMT tweeter, a 6.5" mid
and two 10" bass units all versions had PR's / ABR's fitted.

The nearest to this is venting and its not remotely like aperiodic.

You can't choose a method of bass loading on its own, it has to
go hand in hand with the driver choice, the sensitivity, SPL and
bass extension requirements than can be met for an acceptable
enclosure volume.

DIY'ers cab build very big boxes for relatively small drivers to
extract the best performance out of them but commercially
that is suicide, manufacturers used optimised compromise.

IMHO for a given box size nothing gets close to an overdamped
vented alignment as long as the tuning frequency is low, near
the audible limits of low bass due to loudness curves, and
it becomes effectively the bass limit of the system.

for a given box size, nothing else will dig that deep and
produce max SPL's down to that point that are comparable.

Good bass extension is no good without clean SPL capability
to back it up, and that SPL requirement depends on room size.

People wiil say "so and so" is better. It isn't. Not when you
you compare all the factors involved in reaching a compromise.

You can design an overdamped vented box that is around
50% bigger than a butterworth sealed box that has a quasi
first to second order roll-off down to the tuning frequency.
After that group delay and response goes west, but it
doesn't really matter if its tuned very low.

The vent or PR progressively reinforces the bass drivers output,
~ doubling it over the low bass range and quadrupling it at
the low frequency cut-off point, it slaughters a sealed/aperiodic
box with the same divers for extension and output capability.

TL's can do something similar and they can be arranged to
take bass extension for a particular driver even lower, but
thay are usually much larger and more complex to build,
Or for the same box size you need a smaller, less capable
bass unit, so you get extension but lower SPL capability.

Waffling on about this and that arrangement being
better than another arrangement is just waffle.

Done properly they all work, and they all have limitations.
The art of optimised compromise is choosing your limitations.

rgds, sreten.

Take this bass driver, volumes are per driver :

http://www.europe-audio.com/Product.asp?Product_ID=7958

The classic vented box cuts off in the 30's and will sound like it in room.

The larger sealed box will sound marginally tighter than the smaller.

Note the smaller overdamped vented closely matches the 0.61
roll off at a deeper level (due to port output) right down to 20Hz.

What you can't see here is the further extra power handling
and SPL capability centred on the 22Hz port tuning frequency.

You may say what is the point of discussng 20Hz when its 10dB+
down. Room gain and / or active bass EQ is my answer to that.

FWIW the classic vented alignment wil go louder on most material
than the overdamped box as its tuning is higher. the overdamped
box is simlar to the sealed boxes capabilties higher in the bass.
 

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Sereten, I agree with your assesment, except not all AMT3's were PR designs. The early 4 coil 4 ohm woofer design were first designed and manufactored sealed. They used a Zobel network with those woofers- which used larger voice coils and Alnico magnets then the later 3 coil PR designs.
Later they decided to vent the box, and finally went with a 3 coil network with 8 ohm woofers.
No it's not a Aperodic, but there are obvious reasons why they over stuffed the cabinet.
A can get some equipment and do some near feild measurements, but my ears (as well a quite a few other people who have listened to them) tell me it works well in this configuration, and that's what ultimatly matters in my case.
My ears are old, but they are still pretty sharp.
 
sm19422 said:
Why can't Eminence or another USA company design and market a tweeter comparable to the ones made in Denmark? I would be happy if one made in Mexico, Braszil, Canada, Venezuela or Cuba rivaled Denmarks best at a significantly lower price for the use in one of my t-lines. Series crossovers would also be a nice topic to discuss.
Click to expand...

Try a AMT Heil-you could go the small sealed back midrange route similiar to the ESS PS1220. USA made, and can be had fairly cheap.
I picked uo a NOS Great Heil still in the bow with 4 brand new diaphrams for around $70.
 
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