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Old 4th August 2008, 01:12 AM   #1
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Default Midrange + midlife crisis

Hi...I have loved my Audionics TL90 speakers since I built them from a "kit" way back in 1975. I replaced the tweeters (Peerless) with Dynaudio D28-2's. . I'm now considering (upgrading) mid range drivers. The original 30 year old "Radford" midrange drivers are sealed back units manufactured by Goodman U.K. For now I've been looking at Morel (MDM55 and EM1038) and Dynaudio (D54AF and D76AF). I need a speaker with a sealed back as they are in the TL cabinet with the woofer. Any comments on these 4 midrange speakers (or others) will be greatly appreciated.
I intend to use the same 3 way Radford crossover which I understand is quite good.

PS Has anyone bought "used" drivers before? Any luck? I've seen some on this forum.
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Old 4th August 2008, 04:34 AM   #2
Pano is offline Pano  United States
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Nice to hear you have the same kit speakers 33 years later!

I doubt you will find a new mid driver that will just drop in and use the same crossover - but maybe someone here will know more about your speakers.

Be prepared for a long search, if you want to use the same crossovers.

Have fun, let us know how it goes.
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Old 31st August 2008, 04:32 AM   #3
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Default TL 90 Update - Update

Never confuse motion with progress...I guess I have made a little progress.

I'm liking the sound of the EM1308 mids and the Dynaudio D28 tweets. Nothing "remarkable" and thats the way I like it...just smooth.

I have yet to optimize the set-up. I'm probably going to have a LEAP XO done...I just don't have any data on the original Radford BD25-1 woofers. If anyone can help...I would appreciate. I'm also nervous as to how LEAP will "model" my TL cabinets in the system.

Will update as needed.
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Old 31st August 2008, 05:23 AM   #4
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Default Re: TL 90 Update - Update

Quote:
Originally posted by ronzeman
I'm also nervous as to how LEAP will "model" my TL cabinets in the system.
The TL is, in principle, a special (or "extreme" if you will) case of a ported highpass enclosure. LEAP adopts this perspective to model a TL, and I have used it in that capacity. I believe it gives "acceptable" results, but I do not believe it will be as good as, say, Augspurger's models.

Taking a slightly higher level (and pessimistic) view, it is worth keeping in mind that unlike sealed or vented enclosures, the behavior of a TL is governed strongly by not the enclosure but the "port" itself, and the damping material in the port - both of which are far more difficult to model accurately than a more enclosure-dominated enclosure/port combo. So be prepared for a lot of empirical trial-and-error work, no matter whose model or software you choose.

(Endnote: "pessimistic" if you like computer-based designs that lead to more or less predicted results, "optimistic" if you like to hate software and love empirical trial and error!)

-Ram
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Old 31st August 2008, 08:46 AM   #5
infinia is offline infinia  United States
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Hi

Are the mids still good? If they are, I would think of keeping them as original or stock as possible and just build a new system, since it appears a complete redesign of the X-over is in the works. That way you could compare the results. YMMV

The mid dome in this project is suppostably be pretty good from low Fs & IMD testing. see link below
http://www.zaphaudio.com/ZDT3.5.html


RS52AN-8 2" Dome Midrange Specifications
Power handling: 60 watts RMS/90 watts max
VCdia: 2"
Impedance: 8 ohms
Re: 5.4 ohms
Frequency range: 500-7,000 Hz
Fs: 325 Hz
SPL: 91 dB 2.83V/1m
Dimensions:
Overall Diameter: 5-1/8"
Cutout Diameter: 4-1/8"
Mounting Depth: 2-1/8"





love your quote.
"Never confuse motion with progress..."

Although i think many people do...
cheers,
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Old 1st September 2008, 12:27 AM   #6
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Default Re: Radford Mids Good?

Nope they are toast. Need a total recone job. 33 years ago they were a decent driver but there is better available today. Mechanically they are interesting. The sealed back is very close to the cone area. I understand they were a little peaky in spots.

I've always had an affinity for domes.... Morel has a very good reputation for making decent dome mids and tweets. (and a sealed back version too). Based on that I bought the EM1308s. So far I like what I've heard. More tweaking ahead.
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Old 1st September 2008, 08:26 AM   #7
infinia is offline infinia  United States
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Hi
Are you sure the woofers aren't on their last legs?
I would inspect (esp. poking the surrounds) very closely before you continue to make this kind of investment of retro-fitting. Yes?
Seems the odds are 66,7% that their gone as well.
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Old 1st September 2008, 03:39 PM   #8
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Default Woofer Condition

These units have held up remarkably well. The surrounds (suspension) are a material that looks like shiny black mylar and extends from the basket edge across the cone to the under dust cover. I just completed the refoam on one woofer using a kit I bought from The Speaker Exchange. I had to tweak it as the fit was not perfect but results are not bad. The other woofer I'm leaving as is for now.
Most of the problems in the Radford woofers has been the failure of the original adhesives. About 12 years ago I decided to "modify and repair" one of the woofers as the result of a small tear to the surround. I drew a bead of Dow Corning industrial grade silastic material around the edge of the surround. It worked great. The material is a good adhesive and remaims flexible. That "temporary" repair is still in place. Silastic material may last another 30 years !

I'm open to examining replacements too; but I would rather not spend the $ if I don't need to. I read where the Morel MW1075 was a good replacement. Anyone have experience with that model in a TL enclosure? I'll need to be careful selecting so the effective cone area is same (or smaller) then the Radford BD25-1.
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