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JBL 2470 - are they superior to the K 55?


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Al will be receiving a set to compare.

I looked at the curve that appears above beofre buying the 2470's. Doesn't the horn make a huge difference?

I also read that the 2470's are rated down to 300hz "for speech applications." My guess is that with ESN 400's they can safely go down to 400 hz (and hopefully wil sound good).

Chris

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Point well taken Dean.

However, my point was that the horn used in the JBL spec sheet may have a steep rolloff below 500 HZ. All three of the horns used in the above graph are "good" down to 400HZ according to the graph (the Tracthorn and K-400 were both designed to go down to 400 HZ and apparently, the Altec 511B is also capable fo going down that low). Of course the k-55 driver is also "good" down to at least 400HZ as can be seen by the graphs. It will be interesting to see the JBL 2470's response curves on these horns.

Chris

PS - Dean, please email me. I need to order 4 Auricap 20uF's and 4 Auricap 22 uF's to build a set of ESN 400's. Thanks.

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DeanG......Your graphs are incomplete.... Where are the polar plots...Both horizontal and verticle.. If you stick your graphs to the wall & step back across the room you,l see they (bandwith) are all the same. My brain at 60 is better than yours was at 20.

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Guys,

The curves above were done by Lee Clinton (Arketype) in his back yard. Each was set equal at 1 KHz. I did plots on the Trachonr at 30 and 60 degrees off axis and found the response to be the same by each curve was attenuated as you go off axis.

I think the big advantage of the JBL is that it is a true 1 inch throat. The K55 is more like 0.7 Inch diamater. The Trachorn is also 1 inch where the K400 is about .7 In. This should make the JBL sound cleaner, especially a higher levels.

Al K.

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"My brain at 60 is better than yours was at 20."

Of that there can be no doubt. I hope you weren't offended, I was just yanking your chain. The only thing I was trying to show with the plot is the behavior of the different horns at the extremeties with the same driver.

Good off-axis response doesn't interest me as much as lower distortion.

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DeanG......No offence taken......Lowering distortion is always my primary objective. Tube amps always have 10X more distortion. than SS ...But the euforic harmonics in tubes are pleasent sounding. Marantz 8b the lowest measurment of vintage amps. About your horn plots....All are simmiler, no distortion there. On axis plots do not give you what you hear in the room. Unless your useing your Khorns as headphones. You can lower distortion in mids by going to 2" drivers ....2470 (1"phenaulic) Is no substitute for 4 times the radiating area of a 2" driver. Lower distortion through 3 or 4 slit phase plug brings better clarity. The mass of a lighter diaphram extends upper bandwidth. (but not always). If you only sit in on axis of horn why go to all these horn shapes. A narrow connicle is all you need. And be damnd about room enviorment. Get on your brass nuks a good fight on this subject is needed. I will be gone til friday eve. Meet you all in the back alley. LOL

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My not-so-humble opinion is that practically anything is better than a K55, although I must point out that the horn it is mounted in is the larger determiner of performance than the respective driver.

It stands to reason that the driver in question may be getting a bad rap from me.

DM

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I replaced my K 55 (X) with JBL 2482 (2".. w/phenolics, 25 lbs...friggin land mines) and using the same horn as D man. It's a level of purity in sound hard for me to describe...it's just plain clear...especially vocals. I'm going to trial Al's ES crossover in place of the AK-4s which are now running the whole pile (JBL 2404s too). I learned there's a lot of choices and a lot of opinions about those choices when it comes to the mid-range issue. Comes down to it and you just decide on a direction and shoot. Mebbe there's no correct or best answer...mebbe someday we can all bring our speaks to a common arena where the same system can drive each set in the same setting and we can all vote.[;)]

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The Radian sounds better than the 808 diaphragm, but the aluminum 802 sounds even better.

The Radian replacement for the 2" JBL sounds good, if using a tweeter. I had some reliability issues for pro use. While they do offer a three year warranty, that isn't of much use when it fails at a job and you don't get paid. For home use it may not be an issue.

Radian charges $20 extra for their 2482 diaphragm, all they do is re-drill some holes in their standard 1245 model. I can drill my own holes.

If you re-drill two holes in a 1" JBL diaphragm it will fit into a 1" Altec (same guy designed both drivers).

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