Source for Alted 902 Drivers??

[Mick Bell]

Does anyone know a source for Altec 902 Drivers?

Thanks,

Mick Bell

[Al Klappenberger]

Check out Great Planes Audio:

http://www.greatplainsaudio.com/

I think they are actually making them from original Altec dies.

AL K.

[IB Slammin]

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On 1/10/2005 7:15:17 PM Mick Bell wrote:

Does anyone know a source for Altec 902 Drivers?

Thanks,

Mick Bell

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Bill at Great Plains Audio in OK City. Worked at Altec for 20 odd years. Owns the original Altec equipment. 8 or 16 ohm.

AND, they are new! +/- $400.00 pair. Try 511b's. Will they sound better than your K-500/K-55's?

Regards,

Terry

PS: Give two-way a shot and let the 511/902 go up to 22. You might like it.

[IB Slammin]

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On 1/10/2005 8:06:31 PM Al Klappenberger wrote:

Check out Great Planes Audio:

http://www.greatplainsaudio.com/

I think they are actually making them from original Altec dies.

AL K.

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Yep,they are.

TC

[Mick Bell]

Al, I'm assuming I'd need 8 ohm 902's for use with 811b horn, ALK crossovers, and K-77-F Tweeter. Is that correct?

Mick Bell

[Tom Mobley]

Ah, the K-55 is a 16 ohm driver. You'd probably want the 16 version of the 902. Otherwise, crossover mods will need to be looked at.

[Mick Bell]

Thanks, guys, for the info. I appreciated it very much.

Mick Bell

[hwatkins]

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On 1/10/2005 8:53:14 PM Mick Bell wrote:

Al, I'm assuming I'd need 8 ohm 902's for use with 811b horn, ALK crossovers, and K-77-F Tweeter. Is that correct?

Mick Bell

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You can use either the 8 or 16 ohm versions as long as you make the appropriate Xover modifications. I have found that this is easiest with the compression drivers than with the woofers. Now, to take the position you will get from Al - to be as near perfect as possible you should put the horn on the driver and get a 'real' theile small measurement before finalizing the crossover. The big however is that JBL/Altec did a pretty decent job of measuring their drivers and you can usually get good results off spec sheets (although my quick look only showed measurements for this driver with a 511b).

If you are going this far, have you considered the JBL 2404 as a replacement for the K-77? In my mind's eye I would do this with the K-55 - I really like the 2404 tweeter. I would think it would work well with the 902 as well.

[sfogg]

"If you are going this far, have you considered the JBL 2404 as a replacement for the K-77?  In my mind's eye I would do this with the K-55 - I really like the 2404 tweeter.  I would think it would work well with the 902 as well."

Probably not even needed, the 902 does well up into the treble all on its own. It is a better HF driver then a K77 is.

Shawn

[Mick Bell]

Thanks, I'll take a look at the 2404.

Mick

[TBrennan]

Shawn---What horn are you using that you're getting such good highs? All compression drivers roll-off power response around 2-4khz and extended response on axis is very horn dependent.

Mt experience with 1" high performence compression drivers is that they can have very nice highs, very smooth and clear, but not particularly extended.

[IB Slammin]

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On 1/11/2005 12:20:41 PM sfogg wrote:

"If you are going this far, have you considered the JBL 2404 as a replacement for the K-77? In my mind's eye I would do this with the K-55 - I really like the 2404 tweeter. I would think it would work well with the 902 as well."

Probably not even needed, the 902 does well up into the treble all on its own. It is a better HF driver then a K77 is.

Shawn

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Thanks for saying it Shawn. Guess I was trying to be too diplomatic.

Terry

[djk]

I always laugh at the guys that use a wide range driver without a tweeter.

"It goes higher than your dog can hear"

A few days/weeks/mont later they are adding a tweeter.

The power a compression driver puts into the throat of the horn rolls off at 6dB/oct above 3.5Khz for over 99% of all compression drivers.

Now you can build a horn that gets so narrow at higher frequencies that it will measure flat to whatever, but it will still sound rolled-off in the high end in a real room. Because of the decreasing directivity at higher frequencies there will be no energy in the reverberant field.

The way they get around this in a theater is to EQ it in the reverberant field, and anybody listening close up gets their eyebrows shaved for no extra charge.

Constant directivity horns have to be EQ'd to be flat up close, but this same EQ makes them flat in the back of the room too, so they sound better.

I still prefer the sound of the three way better.

[sfogg]

Tom,

"-What horn are you using that you're getting such good highs?"

511B. It isn't that the 902-8B/511B is particularly extended it is that the K77 rolls off like a dog. Mine did about 10kHz then rolled off badly from there. My 902s (with the lighter 'A' style diaphragms) get higher then that pretty easily. I've posted measurements before of the two and the 902 beats the K77, like I said. I did not claim it was the end all be all high frequency transducer.

Djk,

"A few days/weeks/mont later they are adding a tweeter."

Well it has a been a year so far.....

"Because of the decreasing directivity at higher frequencies there will be no energy in the reverberant field"

Actually my reverberant field isn't based on the front speakers and the random uncontrolled influences of the room for its energy at all. That is supplied by the surround speakers. My room is very heavily treated to avoid extraneous reflections so that the L/C/Rs high frequency horn/driver is getting more directional at higher frequencies is a benefit, not a negative in my setup.

Shawn

[TBrennan]

Shawn---I understand; I've used 902s on 511s too and found the highs very nice. I measured 902s on 511s flat out to 16khz, the highest slice in my RTA.

IMO the T-35 is a rather coarse device, one that literally gives my wife a pain in her ears and neck, thus my Heresys have been banished to background duty and replaced (until I do something better) by KRKs in my main rig. It's ironic that I can play the little KRKs considerably louder than I could play the Heresys.

Maybe I should look for some Heresy IIs or Fortes with thier better tweeter.

[sfogg]

Tom,

" I measured 902s on 511s flat out to 16khz, the highest slice in my RTA."

That is pretty close to what mine where doing too.

This is one of my 902s on the 511b playing pink noise fed full range...

This is the K77 playing pink noise fed through an ALK Type A crossover....

Shawn

[TBrennan]

Very informative.

[IB Slammin]

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On 1/12/2005 1:10:16 PM djk wrote:

I always laugh at the guys that use a wide range driver without a tweeter.

"It goes higher than your dog can hear"

A few days/weeks/mont later they are adding a tweeter.

The power a compression driver puts into the throat of the horn rolls off at 6dB/oct above 3.5Khz for over 99% of all compression drivers.

Now you can build a horn that gets so narrow at higher frequencies that it will measure flat to whatever, but it will still sound rolled-off in the high end in a real room. Because of the decreasing directivity at higher frequencies there will be no energy in the reverberant field.

The way they get around this in a theater is to EQ it in the reverberant field, and anybody listening close up gets their eyebrows shaved for no extra charge.

Constant directivity horns have to be EQ'd to be flat up close, but this same EQ makes them flat in the back of the room too, so they sound better.

I still prefer the sound of the three way better.

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....."I always laugh at the guys that use a wide range driver without a tweeter'......

Then PWK and his Jubilee must be a real Knee-Slapper! I can see it now..a wood K-77 with an attached "buzz box".

Just trying to be a wise a$$.

Regards,

Terry

[Colin]

nice LARGE graphs!