[cushtech]

I am starting the restoration of a pair of ACI Quartz 3-way speakers and hope to perform a few upgrades while I do.  New wiring, new foam and new crossover components.   If anyone out there has information on the crossover, the manual or the kit instructions please let me know.

I've removed the deteriorated foam and the crossover.  Here's the schematic of the crossover (I'm not 100%  sure that it's the original design) and a copy of the page from the ACI catalog. The woofer is a Dynaudio 17W75, the midrange a D54af and the tweeter is a D28.

[cushtech]

Finally finished restoring the Quartz speakers and figured I'd post some pics as there's little information on the web about them.
I updated the crossovers with larger coils and caps so I decided to mount them on the back of the speakers.
The Quartzs are now living in my classroom which I can safely say has the best sound at the school.


Original crossover and variovent.


Defoamed and emptied enclosure.
 

New crossover mounted on the back of the cabinet.


Restored Quartz

[borus]

cushtech Just wanted to say Thank I have been trying to find info on this system for over 20 years. Your post is the most info I have found. I must say that it has made me yearn for more info. You show a drawing of the crossover but you say your not sure it is the right one. Then you show your new crossover did you confirm it was right or did you build from upgrade info? really any info would be great. Thanks again RCT

[cushtech]

I did not find any more information on the Quartz speakers.  The crossover was the same as another pair of Dynaudio 3 ways a friend of a friend had designed back in the 90s and the Quartz's came from him.  Whether the design was originally from Audio Concepts or his I am not sure.  I decided to build the new crossovers using the values from the old one in the speakers.  With the external crossover I can easily tweak things.  They are in my classroom where I teach and I'll actually run some frequency response curves on them later this year. 

[borus]

Thanks again will be looking forward to your measurements. What do you teach?

[cushtech]

I am not the quickest to respond but "stay at home" allows me to catch up on things that have been on the back burner for over a year and a half.
Here is the initial response curve. I did a quick test with REW and a UMIK-1. As I suspected it's a little hot on the high end. I'll need to play around with the lpad. Not ideal test conditions so ignore the other curves I got while setting things up.



I teach computer science and also a intro to engineering class.  The engineering course includes basic circuits, Arduino projects , CAD, 3D printing, robotics and the like.

[cushtech]

Just updating this old thread with some new info on the Quartz speakers.

I found a review of them published in Stereophile, Feb 1988

It confirms that the crossovers in my pair are not the original design from Audio Concepts which were all first order networks.
I don't hear everything the reviewer writes about but the tweeter and mid crossovers I have in place are 3rd order and using Hovland caps.
The bass is as he describes.  A sub helps a lot.

https://worldradiohistory.com/hd2/IDX-Audio/Stereophile-IDX/IDX/80s/Stereophile-1988-02-IDX-105.pdf
https://worldradiohistory.com/hd2/IDX-Audio/Stereophile-IDX/IDX/80s/Stereophile-1988-02-IDX-106.pdf
https://worldradiohistory.com/hd2/IDX-Audio/Stereophile-IDX/IDX/80s/Stereophile-1988-02-IDX-107.pdf
https://worldradiohistory.com/hd2/IDX-Audio/Stereophile-IDX/IDX/80s/Stereophile-1988-02-IDX-108.pdf

[DahaiTX]

I must thank you for this post, I had a pair of these speakers for three years and I have yet to find any information about them. I did not do much to them except for replacing the foams on the outside of the speakers. Please share if you have completed your restoration work.
Old picture when I first got them:




Foam replaced: