On the cheap, I bought a pair of these without the Altec 12" woofers; the cabs did contain pristine examples of the factory mid-ranges, factory tweeters and factory x-overs, however. These have been sitting in my basement waiting for restoration.
What was the correct factory 12" woofer for this system?
I threw in a pair of JBL 12" 2202 woofers to see if they are comparable, but I think they have a different sensitivity.
Are these worth restoring?
Thanks.....
I do remember when these systems first hit the market in the mid-1970s. I believe they were intended to compete directly with the JBL 3-way 12" systems such as the L100, 4312 studio monitors, etc. As I remember, Altec had some production issues and, back then, I never actually got to hear a pair perform against other systems in Hi-Fi stores. They simply were not available in stores.
I assume Altec was focused on the professional market and no so much on the Hi-Fi consumer
The old 1975 service guide lists the woofer part number in the Stonehenge II as #33555, and it is listed as a replacement part rather than a driver that is to be repaired. That usually indicates a fairly cheap driver was used. If your crossovers are in good shape, you might be able to derive some of the info you'll need from the schematic of the crossover. Do you have a good picture of the crossover, or perhaps a schematic?Originally Posted by robertbartsch
- Mike
Your neighbors called. They like your music.
- Since I use compression drivers & horns , that's also my preference for home systems , so
- I think you should eWave those wonderful looking cabinets by using GPA components to create an updated M14, Altecs nod to the proverbial 2-way with a 12" .
- Use GPAs 414-8C , GPA 902-8A with GPA 931 horn coupled to an updated crossover of some sort . Since you have subs , you don't need to worry about max LF extension ( & can concentrate on efficiency ) .
- Sell the existing mids & tweets ( keep the cabinets ) .
<> EarlK
I'd try to find the T/S parameters of the original speakers and then try to find new drivers with close T/S specs
Actually, before this post, I was going to tear the drivers out of the cabs and install an Altec 802 compression driver with a small horn and use the 2206 JBL 12" woofers crossed at 800hz. The 802s have new GPA aluminum diaphrams....
I guess that is what I'm still leaning toward now.
Last edited by robertbartsch; November 19th, 2012 at 11:43 AM.
What is the cubic volume of that cabinet ?
Here's a look ( thanks to Zilch, bless his heart ) at the sort of response one can expect from an Altec driver bolted onto either Zilch's favorite ( cheap ) wave-guide or the Altec MR931 wave-guide.
The traces are remarkably similar ( the JBL PT-F95HF has a tiny bit of extra LF loading ) with the MR931 showing more symmetrical undulations ( the 802/34647 combo will have a different set of undulations compared to the stock 902-8b ) .
Whatever undulations you end up with ( in the HF ) can be dealt with by applying series LCR ( notch filters ) to them ( located across the driver terminals, after the crossover proper ). This ( of course ) assumes you would want flatter response than what's pictured above .
From a resale standpoint- a JBL guy won't want them cause they say Altec, and an Altec guy won't want 'em with JBL woofs. I'm a business manager, rather used to be. So I always think of getting my money back...
I gotta wonder how that pair of 3124's in my closet would model in that box... with the 802/GPA top end...maybe I'll model it if I get the energy...
Your neighbors called. They like your music.
Rob, sell those JBL 2202's . They will never be of any use to you . They are a high sensitivity , mid-range that has few ( to none ) applications within home audio systems .
Get what you can for them & put the money towards buying more project friendly Altec 12's ( such as the 414 from GPA or even OG's 3124's ) .
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