480's LS subs?

[colterphoto1]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220007402106&ssPageName=ADME:B:SS:US:1

Would these make a neato pair of subs for a LS stack? They are exactly the right dimensions 24w x 24d x 27H. 18" and passive 15". Wonder what the specs are on these babies and if they were intended for such use? I notice they have the pole mounts for satellite speakers as well.

M

[DrWho]

oooo, a pair of subs I actually have experience with [H]

For what it's worth, I'm fairly certain they are down-firing 15" active

with a front-firing 18" passive. The passive as a rule of thumb should

have more surface area than the active and a passive can't really be

down-firing due to gravity. I never did get a chance to tear into them

so I'm not certain. Putting your hand on the 18" driver certainly felt

like it was the powered one...

When overdriven, these subs sound like utter crap...more of a buzz

sound than actual farting - I'm pretty sure that's the sound of the PR

bottoming out. They usually come with metal grills on the front and

they buzz all crazy style - but there are ways to remedy that.

At $500 the price seems a bit steep and I don't think they'd keep up

too well with your double stack LSI's. They sound great though, output

down to around 45Hz and at lower volumes you could push it with EQ down

to around 35Hz - very cornwall sounding. I think they perform very well

in small venue type settings at volumes under 105dB, but take em

outside and they really start to struggle. I've never heard

them on a very capable amp and wasn't too smart back in those days, so

perhaps most of the limitations I describe are more the amp than the

speakers themselves. All I can tell ya is my experiences with them (amp was an old unreliable something from JBL).

I don't think they'd compare very favorably to the JBL/EV bass bins you

already own - but I can understand the attraction to go with an all

klispch setup.

Didn't you win an old TSCM bin of some sort a while ago? Why don't you

target a fully hornloaded rig - kinda like what Hunter had in his

garage, but with the dbl LSI's on top instead. That would be one

kicking system and you could take advantage of your wheelbarrow bass

bin trick []

....ya I know....it'd take up more space. We'll have to rig you up a fancy way of storing the system in the air or something.

[bodcaw boy]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220007402106&ssPageName=ADME:B:SS:US:1

Would these make a neato pair of subs for a LS stack? They are exactly the right dimensions 24w x 24d x 27H. 18" and passive 15". Wonder what the specs are on these babies and if they were intended for such use? I notice they have the pole mounts for satellite speakers as well.

M

hey mikey,

would you be surprised if i told you that i specifically designed the 480 so that a ls would fit perfectly on top????? no didn't think so.

it seems that in the old days, don delgado (and i mean don in the spanish translation) had a pair of scalas. he missed the low end bass and when the time came to design a sub for the pro market, he took it upon his blueberry self to make the dims fit a scala. imagine that.

doc,

afraid to disappoint you but the 15" is the drone and the 18" is the woof. a 15" drone don't compress as much a port at the kind of spl's we were looking at.

roy

[djk]

Not to offend anyone (but I know this will), but I wouldn't own one of those.

Tuned to 43hz, it is spec'd to be ±4dB 44hz~200hz

http://www.klipsch.com/product/product.aspx?cid=468&s=specs

A short x-max 18" driver, vs the $89 Eminence Kappalite 3015LF, the KappaLite will have a higher total volume diaplacement (and hence more maximum output).

Another problem with the KP 480 is the PR. It can barely keep up with the volume displacement of the 18 at lower frequencies. The idea was to limit excursion of the main radiator below cutoff by having the PR max out. Most current equipment has filters that may be engaged for this purpose. Users have found the suspension to wear out and sag on the PR, hanging downward doesn't help either.

For best results with a PR, it should have the capability of about 3X the volume displacement of the main driver, be mounted in the vertical plane to reduce sag, and have a removeable transport brace. EV used to make such a system.

If anyone wants a proven design for a high output low distortion sub, let me know. About 20 years ago I designed a push-pull slot-loaded sub for PA use. It is 3dB down at 31hz (low B on a 5-string bass), and recommended crossover at no higher than 200hz. Mid band sensitivity in 2Pi is 103.8dB/2.83V/1M. System impedance minimum is 4 ohms, and will handle 600W without exceeding the x-max or thermal limit of the drivers. The current drivers are an Eminence custom 9mm x-max with a rubber surround, and are about $60 each plus freight. Cabinet is 24" X 30" X 36" overall. Preferred orientation is 24" tall and 36" wide, but may be used as 36" tall. The push-pull operation gives lower distortion that most horns. Worst case vent velocity at a full 600W is 14.3M/sec, about Mach 0.042 (acceptable). Two different dual 15 versions, a dual 12, a quad 12, and two different dual 18 versions were built and evaluated before building twenty-four of the final dual 15 design.

[colterphoto1]

Thanks Roy, does me a world of good to guess correctly on some of these posts. I do realize that it is a much older design, but neat to know that an attempt at a LS sub was made at one time.

Did you guys know that there was a prototype Heresy sub built? I have seen it.

Michael

[DrWho]

No dissapointment here...I always thought they were 18" active until somewhere I 'learned' the PR always needed to be able to displace more volume (preferably with less excursion for efficiency sake). Though now I'm kinda curious for the reason behind the design choice. Would it have to do with parts laying around...say Chorus II passives?

[colterphoto1]

Doc, Think about it, who cares how much excursion a passive has?(within reason of course)

It is not limited by a voice coil, uses no electrical energy for it's movement. I guess it's only physically limited by its surround and spider, right?

[DrWho]

All same diameter drivers (active or passive) need to move the same distance for the same SPL at the same frequency. Take it a bit further and all drivers (any diameter) need to displace the same volume of air for the same SPL at the same frequency. So really there's nothing wrong with using a smaller surface area for the passive as long as it has enough excursion to output the same SPL. The difference between an 18 and 15 is that the 15 needs a little under double the excursion for the same displacement. (8/5 yikes).

The problem is that more excursion usually results in more losses in the spider and surround so the output over the passband will be slightly less for the same input (same SPL for the active driver). I'm not sure how the tuning or Q of the PR changes, but I'd imagine the tuning would move higher? (stiffer suspension?) Ports on the other hand shift down (more apparent mass?). I would think shifting down would be better as it'd help reduce the effects of VC temp. If I remember correctly, Rich said there were a good dozen or two nonlinear systems working back and forth with each other so I'm probably over simplifying the issue. Isn't there a whole set of parameters specifically for modelling the large signal behavior of drivers? There doesn't seem to be much information about the behavior of PRs in the public domain and I know Klipsch has done a lot of research in that department so chances are they know what they're doing [] So far they all tell me PR's are better behaved - just more expensive.

[djk]

"All same diameter drivers (active or passive) need to move the same distance for the same SPL at the same frequency."

Not so.

At resonance the PR must move more air than the driven radiator.

How much more?

3.3X as much, it depends on the Qts of the driver and the type of tuning employed.

A low Qts driver is typically tuned high to use a smaller box with flat response (like the Klipsch design). 1.6X volume displacement is the number thrown about for these type of designs. Tuning to the driver resonance a half octave lower (step-down tuning, EBS, SBB4, 6th order, etc) will require double the volume displacement (hence back to the 3.3X number).

When you find a spare $40 I suggest you obtain a Loudpseaker Design Cookbook by Vance Dickason. While it contains very little original work, it gives a synopsis of hundreds of technical articles spanning decades of research, and is anotated and footnoted as to the original sources so the reader can go to the source.

http://www.audioxpress.com/bksprods/books/bkaa68.htm

[Corvette6769]

No dissapointment here...I always thought they were 18" active until somewhere I 'learned' the PR always needed to be able to displace more volume (preferably with less excursion for efficiency sake). Though now I'm kinda curious for the reason behind the design choice. Would it have to do with parts laying around...say Chorus II passives?

I own a pair of KP-480-AX and confirm that the 18" K-49-K die-cast aluminum frame woofer is the active and the 15" KD-17 is the down-firing passive radiator and since the Chorus II uses a KD-16 15" Fiber-composite cone passive, the KP-480 does not use the same passive radiator.

[DrWho]

So you're saying that a 15" PR playing 40Hz at 120dB needs to move 3.3X more than a 15" active driver playing 40Hz at 120dB?

Thanks for the book reference - I'll add it to my wishlist.

[TomMarbleMan]

Have a pair 4 sale new member 1st post. price?