definitive opinion available? Use JBL 2220 in LS?

[Tom Mobley]

I just can't get myself to like the K-33 with 13x3 slot deal. Some point out that opening up the slot to 6x13 allows (requires) use of other woofers. Mentioned are the JBL D-130, D-140, the 2220, Trusonics I can't find or afford. JBL characterizes the 2220 as a high-effiency driver. I also see some nice 2225's on ebay, but JBL seems to think they are high power handling models, the effiency is not mentioned.

I'm currently ready to buy woofers, and I'm just plain having a hard time believing that a K-33 playing through that small slot is going to sound as good as a nice JBL or similar playing through the 6" slot.

Substituting is attractive, but one of the things I don't see being mentioned much is the impedance differences. I've seen the K-33 characterized as a 4-ohm driver, looks like all these others are 8-16 ohms depending on the exact model. Is any of this right and if so, how does this affect the deal?

Anybody got any wisdom here? Just stick with the K-33 and forget about it? One guy here mentioned using a Pyramid 15" driver, it does close to 100dB at 1 watt, but not one of the names usually bandied about.

Thanks for any time and thought given,

Tom

[djk]

the JBL 2226G would drop right in with no network changes.

[CaptnBob]

Make sure you check the phasing. Many JBL drivers are set up backwards from everyone else (that is, a positive voltage on the red terminal makes the speaker cone hop backwards instead of forwards.)

Also make sure the gasket is thick enough so that the cone doesn't smack into the the baffle during long excursions.

Capt'n Bob

[Tom Mobley]

djk,

Looking through the JBL obsolete website I don't see the 2226. I do see the 2220 and 2225, they're both 8 ohm. The 2220 has an SPL of about 101dB @1w/1m and is 8 ohm. It's been suggested that it matchs up pretty good, does it sound reasonable that the 4 ohm increase in impedance would lower it's output by about 3dB, making it quite close to the K-33 at 96-97? JBL mentions that it's designed for use in horns, high effiency, all that.

The 2225 is about 97dB SPL, but again 8 ohms, going by the guesstimate above it might be around 2-3 dB down to a K-33, not the right direction at all.

What do you think of all this? Any validity to that theory about the 4 ohm difference equating to about 3dB in SPL? I've seen it written that 3dB is just aboout enough to hear?

Any comments from Al, Gil, John, HornEd, et al?

Tom

<Later> OIC, it's not an Obs model, it's a current model. Duh. Those seemingly standardized JBL performance graphs are kinda nice. Anybody know where there's a graph like that for a K-33?

djk, got any idea whether the horn loaded response curve looks like the plain curve or the vented box curve? The vented box curve on those looks pretty good. Need acrobat viewer, but: http://www.jblpro.com/pages/pub/components/2226.pdf

This message has been edited by Tom Mobley on 05-29-2002 at 03:46 AM

[Brett]

Tom,

The 2226 is a current driver. Specs and .pdf link are here.

http://www.jblpro.com/pages/components/vgc.htm#2226HJ

The 2226G is the 4 ohm version, and shows up in the pricelist I have. Jammin Jersey have some, second hand.

http://www.jamminjersey.com/speakers.htm#JBL

HTH

Cheers

[Shock-Late]

I've been using four different woofers in my LaScalas (wich were bought with no original woofers):

JBL D130

TESLA (about the same as JBL D130)

EV EVM15L

KLIPSCH K33E

the only one that gave good results was the Klipsch K33E!!!

why change it? it sounds good!

Frans

[Tom Mobley]

Brett, Frans

Thanks for your replies.

Brett, We posted at the same time to the minute. I had found the current model deal for the 2226G, looks like a good choice. Thanks for the link to Jammin' Jersey, that's an interesting site. $200 apiece, ouch.

Frans, do your LaScala's have the 7.62cm or 15.24cm throat? I wouldn't expect a speaker that sounds good in one to also sound good in the other. If the K-33 worked in your boxes, I expect you have the 7.62, right? I'm going to enlage the slot to six inches in mine, if I do this deal. Hoiwever, it's not looking good due to expense.

Thanks for your time replying.

Tom

[JohnA]

Tom,

You need to decide how much work you are willing to do. If you don't use a 4 ohm driver, you'll have to change the xover. djk knows his stuff. I've never caught him wrong; i'd listen. Also remember that the horn loading makes the driver behave as though the impedance is twice it's free air measurement. An 8 ohm driver will look like 16 ohms.

I see no reason not to try the JBL driver, but try it first with the 3" x 13" slot and measure it's performance. enlarging the slot is not reversible.

The output of the bass horn does not change because the driver impedance rating changes. IOW, if you put a driver in there that is 5 dB more efficient than a K-33, the output will be 5 dB higher unless there is a bad mismatch between the driver and the back air chamber or the throat, maybe.

Follow djk's advice and try the 2226. Just buy one and test it, if you aren't sure.

John

[Tom Mobley]

John,

Thanks for taking time to reply.

I thought I was taking djk's advice.

It appears to me that there's some confusion (probably mine) or poorly understood stuff about the K-33/3" slot combo. I thought the perceived increase in impedance was due mostly to the 3" slot, others seem to think it's the result of being horn-loaded, possibly it's due to to some poorly defined interaction of the two. In any case, I was planning to go to a 6" slot if using a JBL driver. I thought this was the whole point of going to a different driver, to get rid of the 3" slot. It would certainly be interesting to do an A-B comparison of the earlier and later KHorns with the two different driver/slot combos to get a little better idea of the difference.

Now I'm sort of dimly starting to understand that the bass response of the LS's I'm putting together is really determined by the horn length/mouth size combination rather than the quality of the woofer as I had previously supposed.

I'm still fairly new to this whole deal and had gotten the impression that the reason the 3" slot arrived on the scene was to allow the use of a less expensive driver while still retaining acceptable response. I thought, "OK, get a better driver, go back to the 6" slot, get better tunes." Looks like it's not that simple, too bad.

Comments, anybody?

Tom

[JohnA]

You are correct that the bass response is largely defined by the size of the horn and that the increase in impedance is due to the horn as well. There was a magazine article that discussed the difference in response between the 2 slot sizes, It was quoted on this forum. Look back in messages about 3 months old. The conclusion was there was only a little difference. Over the years the K-33 has been tuned to be the best performer in the Klipsch bass horns. It's happy coincidence that it's cheap. PWK used some of the best woofers made in earlier days. If one was better than the K-33, I'm sure it would have been used in the late models.

John

This message has been edited by John Albright on 06-01-2002 at 09:59 AM

[Tom Mobley]

Thanks, John.

I guess I'll order up the K-33's on Monday morning. Last of the Solen caps they shorted me came in yesterday, I've got the K-400's and some other stuff from a member here, the boxes are supposed to be shipped from Chicago, this deal might actually happen soon.

One thing for sure, I could have bought some cheaper, lots cheaper. Oh well....

Tom

[jnorv]

If I calculate the flare rate of the LS bass bin, I get a rough estimate of the theoretical cut off frequency of about 60 Hz. If I extend the horn another foot, the mouth area becomes 8 sq. ft, (4x2 feet). Has anyone tried this to see if the base response becomes smoother? Hate to reinvent the wheel.

J Norvell

[edwardre]

Tom, looks like you've got good answers here, just a tidbit more of info to chew on....

I asked Kerry, owner and proprieter of "The Vintage Audio Trader's" site about woofer ohms in general. The rest of this reply is his testimonial regarding the older woofers:

For reasons having to do with reactance annulment, Paul Klipsch

specified special low-impedance drivers for the Klipschorn.

They were made by EV and Stephens Tru-Sonic especially for use in

Klipschorns and Klipsch-licensed copies.

The EV15W k, and the hammer-tone blue LX-103-2 are those drivers; both

have Klipsch-specified 3.6 Ohms DCR ( 8 Ohms nominal impedance ).

The buyer had a choice.

I have the original blue LX-103-2's in my 1954s. I only use the K-horns

as subs though...from 100 Hz down. I get rock solid,' real ' sounding '

low bass from those things ! Flat at 30 Hz with usable output to 25.

Anyway, the Stephens LX-103 is a 16 Ohm non-Klipsch woofer and was never

- or should never be - used in K-horns. It looks pretty much the same as

the 103-2 except it usually has a silver basket with a dark maroon

magnet.

The 16 Ohm 15W is to the 8 Ohm 15W-k as the 16 Ohm LX-103 is to the 8

Ohm LX-103-2.

By the way, and you probably already know this, don't confuse nominal

impedance with DCR. D.C. resistance is related but different; it's

usually about half the nominal A.C. impedance.

You measure ' impedance ' by sweeping an A.C. signal generator through

the speaker and then measuring A.C. resistance at specific frequencies.

The " nominal impedance " is usually given as 1/2 the resistance

measurement at the resonant frequency spike.

In other words, a ' nominally ' 16 Ohm speaker usually measures 32 Ohms

at the resonant frequency.

Which is why Klipsch specified 8 Ohm ( 3.6 DCR ) woofers for the K-horn;

they are woofers which have a 16 Ohm impedance at the resonant

frequency.

16 Ohms is the perfect electrical *resistance* ( at that point of

maximum excursion ) to, along with the back chamber, ' null ' out the

horn / woofer system's acoustically *reactive* components in the throat

/ front chamber.

This achieves throat reactance annulment, which equals optimum damping.

That's my understanding anyway.

------------------

Ed

[Tom Mobley]

Well, there's stuff in your post that I don't really understand. I'm not an EE, just an "almostaME."

At any rate, I ordered the K-33's from Klipsch today. Discovered they have the little brackets for the back of the K-400's too, got them also. We'll see what shows up.

Thanks for taking time to reply,

Tom