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View Full Version : Altec vs JBL tech info



Russellc
12-22-2007, 07:36 AM
Anyone know why it is that there is so much technical info out there for JBL
(thank goodness) but when it comes to Altec, about as high tech as it gets is "just use a second order cross over and hope for the best" type of advice?

Zilch, any interest in going through drivers and horns like 515 8G, 416 8C (both available new from great plaines) and 902 and 802 8G with 811B and 511b horns like you have the JBL 2 ways? I am sure many of use have Altec stuff not being used that could be lent to such a project.

Russellc

Zilch
12-22-2007, 03:11 PM
It's almost as if there is some point in keeping the info, well, "tightly held," isn't it? Surely GPA or Iconic has the T/S on what they make and sell. When I've suggested that before, the answer has been, "Well, maybe not...." :dont-know

As may be seen in the "Babies" thread, it was really frustrating that nobody seemed to have much information or any data on the Altec components. Putting it together wasn't easy, and when it was all said and done for that particular combination, after all that combined effort, the response from the "aficionados" was "You haven't revealed anything everybody didn't already know for the last 40 years." :wtf:

The compression drivers are fairly easy, as I have the horns, and it's just a matter of bolting them up and taking the measurements. That doesn't tell the full story of how they perform in systems, of course, but it's still quite a lot, providing the basic characterization and revealing differences among them. In some systems, the horn stands separate, of course, and the data should be fairly close for them.

If somebody wants to send me compression drivers, it's not a lot of work to get the info. I'll also need something as baseline for comprarison, as I have no Altec drivers here anymore. I can talk to Steve Bliss about lending me his 806As on a long-term basis, maybe. I measured them recently, and they're in good condition and well matched (below). I'd also like another pair of those to put Radian diaphragms in, or with them, for evaluation. I'm reluctant to open Steve's up to do that, as I consider them a "Standard" for comparison.

The woofers aren't quite so easy. I have cabs that will fit the 15" versions, but not the 16s. Mounting them motor out might get it fairly close, though. Measuring nearfield frequency response with a known tuning or closed box is easy, but it's T/S parameters we really want, and I can't get Vas precisely except in a test box. I'm saying the woofers are more of a difficult task, and we really need multiples to assess the inter-unit variability. Anybody can do the woofers with WT2/3, a test box, and some practice. I'm suggesting maybe somebody else, or several others, might undertake the Altec woofer T/S project on an organized basis here. :yes:

Russellc
12-23-2007, 10:02 AM
Ok, you have the horns, unfortunately I have sold all my 802 8D pairs, my set of 902 8B, and the 908 8B pairs. I still have a pair of 808 8B which have been converted to 802 8G, they are currently on my A7s however once my JBL project is done they would be available. Similarly, I have a pair of the 416 8C in them, but do have a pair of the 515 8G laying around, what sort of equipment do I need to calculate Vas? I presume the old published Altec info is not accurate? I have a hard time thinking Bill of Great Plaines wont reveal Vas, unless he doesnt know. The Iconic people are tighter lipped, but they manufacture no drivers, Bill does all that for them, is my understanding anyway. I would be glad to participate in such a discovery process, but knowledge of testing is minimal, as is testing equipment. Im a quick study if anyone cares to elaborate and "dumb it down" for me!

Russellc

Mr. Widget
12-23-2007, 10:18 AM
I would be glad to participate in such a discovery process, but knowledge of testing is minimal, as is testing equipment. Im a quick study if anyone cares to elaborate and "dumb it down" for me!Order one of these and you are on your way.

http://www.woofertester.com/wt2product.htm


Widget

Russellc
12-24-2007, 07:42 AM
Looks very interesting, has anyone here used this model? the pro version looks really sweet, but 990.00 is a bit out of price range!

russellc

Gary L
12-24-2007, 09:11 AM
Is this another of those "Here we go again" deals!;)

The "Babies" thread produced some very valuable info but I'm not entirely sure many here found it to be of much value!

I am just about out of my speaker building phase but certainly not out of parts and pieces to do it. I probably have sitting here on shelfs all that you guys might need to do the testing but I am on the other side of the country and simply can't afford to ship this stuff at this time of year when there is no work.

I have a single model 19 cabinet that would fit any of the stuff you want to test, not pretty but solid. I have 416 woofs in the 8A narrow lip and wide lip and also 416-8Bs and a couple 414-8Cs. I have 19 XOs and 1201-8As and just about all the 802 and 808 drivers. Plenty of 811B and 32 horns but no 511s.

What I don't have is the cash to be shipping this stuff back and forth or a need for the valuable knowledge to be learned from the exercize.

Most of this stuff will remain on the shelves until the values get to where I can get my money back.

http://img.photobucket.com/albums/v722/Gamalot/Speakers/DSCN1748.jpg

http://img.photobucket.com/albums/v722/Gamalot/Speakers/DSCN1749.jpg

http://img.photobucket.com/albums/v722/Gamalot/Speakers/DSCN1750.jpg

http://img.photobucket.com/albums/v722/Gamalot/Speakers/19set1.jpg

http://img.photobucket.com/albums/v722/Gamalot/Cabinets/Altec19restobegins10-18-06007.jpg

Gary

Mr. Widget
12-24-2007, 01:37 PM
Looks very interesting, has anyone here used this model?The $160 version is quite sufficient.

Try the search function... you are missing out on most of the fun here.:D


Widget

Zilch
12-24-2007, 04:06 PM
Looks very interesting, has anyone here used this model? the pro version looks really sweet, but 990.00 is a bit out of price range!WT3 is also available at Parts Express. I may upgrade my WT2 and also get WT3 to compare. In any case, either will do what you propose, which is to obtain and/or verify the woofer T/S parameters.... :yes:


The "Babies" thread produced some very valuable info but I'm not entirely sure many here found it to be of much value!DUCK! INCOMING over the wall!

Well, if number and intensity of flame wars elsewhere is any indicator.... :p

DonM
12-24-2007, 06:39 PM
Zilch,

Have you posted an impedance graph for those Altec 806's?

By the way I have used a variation of the N800F crossover with my Altec 416a's which were much better than the N800D that came with them.

Your Valencia project inspired me to try them one more time.

Regards,

Don

Zilch
12-24-2007, 08:11 PM
Have you posted an impedance graph for those Altec 806's?If I did, it's most likely on some not-so-good ones. I did not measure impedance on the really nice pair which came through here recently, but I may be able to get them back for that.

I don't know if everyone's getting what's shown in the curves above; I've received a couple of PMs about it:

1) The stock N800-F crossover removes some of the upper midrange emphasis (read "Shout,") but does not extend the HF. The filter "Q" also deepens the notch at 2.5 kHz (bottom curves).

2) Biamping using the Behringer CX3400 with its CD compensation engaged removes all of the shout, smooths the response, and extends the HF to ~14 kHz (top curves). The delay function may also be used to correct the time alignment by delying the woofer to compensate for the inherent misalignment of the acoustic centers of the drivers.

This analog active crossover lists at $130 in the current Parts Express catalog, but you can likely get it for less at your local Guitar Center or similar pro audio retailer. You'll also need a second amp and XLR cables.

How well 806A handles the 10 dB "boost" in actual listening, i.e., the quality of the extended HF response, I don't know. When I did it earlier, passively, it sounded fine to me, but I never had full stock Valencias here for evaluation during that time.

The CD compensation built into other crossovers or amps may work as well, or better. I just tried this particular one in response to an inquiry in another forum, as I had it connected in my system at the time for another purpose. I do know that the compensation curves vary with different manufacturers from prior experience, i.e., there does not appear to be a "Standard" EQ.

If you want full HF extension to 20 kHz, you'll have to move to alternative drivers or, perhaps, different diaphragms; it does not appear that 806As have the capability of delivering such extended HF response in stock form....