microTower bipolar ML-TL for CHR-70 or EL70

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I have just looked back at the date of my original post...16th October 2010!

Could possibly be a contender for the longest speaker build! :)

Anyway, back on track and due to fit the drivers and complete the build by the end of the week

3e2686a6-8de9-4f6b-83d0-9964ce117ba1.jpg



I am grateful for any comments you may wish to leave
 
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Great thread. I have a rough looking pair of Epi M75s that I'm trying to fix up. They appear to be identical to the MT-1 but with rubber feet rather than extending the corners to the ground. The drivers are CTS and supposedly the same as those originally used in the Bose 901 series I. The cabinets are so rough that I might just build new ones rather than try and patch up the current ones. I realize that this project was geared toward a specific driver but does anyone have any comments as to how I may improve on the original design?

I have no way of measuring the drivers and don't have specs for the CTS Bose drivers. I suppose that without that info that replicating the original cabinets would be best.
 
You might want to see if the folks at Human Speakers are still active, and can answer your questions as to the specs for the 4.5" full range driver listed as used in the MT1 & 2 ( PRO 024) Of course any T/S parameters they'd have would be for "current production equivalent" - or would that be NOS? - and might not be of much help with designing an enclosure for well seasoned drivers using modern modeling tools. Second guessing / reverse engineering the original design and attempting to improve upon performance for the specific drivers would likely be an exercise in futility without that data.

HUMAN Speakers: Home

Not that it probably matters much, but unless these folks or other authority can confirm the proposition that the drivers were the same as Bose 901 Series I, I'd be inclined to consider that an urban myth.


As I've posted more than once in this thread, I sold these back in the day (yup, 40yrs ago), and even fresh from the factory carton, the quality of construction (miter fold and hot glue with minimal glue battens, IIRC) , as well as finishing left a lot to be desired - any DIYer not capable of building a better enclosure should hang up his brad nailer and veneering iron:D
 
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Yeah, kind of figured it would be a futile exercise without the specs. I'll probably end up building new boxes eventually.

I did try and email Human Systems but never heard back.

As for the Bose thing, both drivers were supposedly made by CTS and look identical. It doesn't mean that they're to the same specs though.
 
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They look very nice. Well done!

I was thinking the same thing re: bass. My EL70 microTowers required at least 100 hours before I started getting good bass. I see those are CHR-70; I suspect they require less break-in, but some improvement should be expected as they get more hours of exercise.
 
...and of course...

... nothing that a few good watts can't fix.... hmmm, 30 watt/ch arc-welding capable amplifier;). Get ye self an old 2BLP (best sounding Bryston amp ever made in my experience, 50 Watts/ch) and a suitable preamp and have at it (or any Nelson Pass designed amp such as the Thresholds, passDIY designs, or even one of the Pass designed, Threshold licensed Nakamichi receivers or amplifiers). I have a Nakamichi STASIS SR-3A (30 Watts/ch) that is mighty nice to listen to as a single box no fuss solution.

If looking for something more "pedestrian" even some of the old Harmon Kardon integrated amplifiers and receivers can swing a good amount of current. An amp I hated when I sold them new (mainly because finding a good speaker match for it to sound its best) was a Harmon Kardon PM665 (100w/ch, capable of a peak of 60A!). I may have to find one and use it as a workhorse for hard to drive (as in current hungry) speakers, or as a "break-in" device.
 
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