10 replies to this topic

[JKent]

I've been working on a pair of 1979 Ohm Model L speakers I found at the Sal for $4.99. Woofers needed refoaming of course, and I replaced the xo caps (8.2 and 2.2 'lytics) with film. Three of the originals were within 10% and one 2.2 was within 20% but film is better. Used a nice "filled fillet" surround from MSound. As always, I removed the dustcaps to shim the coil. In this case I found globs of what looked like axle grease inside. I emailed Ohm (still in business) and basically just got a sales pitch in return, but according to John at MSound and Bill at Millersound (and others) that was a cooling grease.

I seem to recall Tech Hi-Fi was the only store that sold these back in the day. Here's what it says about the L on the Ohm site:
"The Ohm L is the most popular speaker Ohm has ever built. It was designed to have the deep bass of the popular Advent Loudspeaker in a much smaller cabinet by using optimal venting techniques. . . . The system received rave reviews."

Here is a description: http://www.ohmspeake...rt_ID=682376089

I have not found the rave reviews. In fact, there is little on the 'net about the Model L (AFAIK). They are similar in design to the AR2ax insofar as they are basically 2-way designs with an added supertweeter (but they are bass reflex). The tweeter & supertweeter are kind of chintzy looking (photo below) while the woofer is more substantial. Anyway--it will be interesting to do an A/B comparison with the Advent OLA, since that was their "target". They are smaller than the OLA:

• Ohm: 12"w x 9-3/4"d x 20"h about 29 pounds each
• OLA: 14-1/4"w x 11-1/2"d x 25-5/8"h over 40 pounds ea IIRC

Just a tad bigger than those "other" Brooklyn-born speakers, the Rectilinear Mini III (they are 12 x 9 x 19). Too bad I don't still have those for comparison.

The Ls should be finished soon. Total investment: about $35 (including the caps that were in my parts box).

Anyway...after cleaning them up (they were filthy) the Ohms sure look nice. Will post some listening impressions soon.
Kent

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[JKent]

oops

Edited by JKent, 29 February 2012 - 04:49 PM.

[JKent]

Quick follow-up. The Ohms do sound nice and the bass is pretty amazing for relatively small boxes. I'd say they do indeed rival the OLAs.
Nice speakers but no room for them so out they go. A fun project and it's interesting to compare a number of speakers. In this case I listened to the Ohms, OLAs, AR 91s and my current favorites--modified AR 3(a)s. Also have some Bozak mini monitors in the mix but did not really compare those to the Ohms.
So I sold the Ohms on that auction. Buyer will get some very nice sounding & nice looking speakers for a bargain price. Glad I could revive these neglected gems
Kent

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[bikdav]

Yes. I remember the Ohm L. My ears never told me that they rivaled the Old Large Advents in any way. But the Ohm L bass was never anemic for its size either.

[Mystery]

Hi JKent,
I have a pair of Ohm L's but someone had replaced the woofers with some generic woofer from parts express.
Ohmspeakers sells replacements but I'm not going to spend $200 just for the woofers.

They do sound very very good as it is even with generic 'Goldwood' woofers but wondering if they can be improved with recapping.
Could you please share what caps/resitstors did you use and their cost?
Thanks

[JKent]

See post #1--8.2uF and 2.2uF. I used a Dayton poly film for the 8.2 and a mylar 2.2. Brand does not matter--just use film caps. Carli caps from Madisound are good. They come in 2.2 and 8 (close enough) and are very inexpensive: http://www.madisound...rli-capacitors/
The resistors are 7w sand cast and do not need to be replaced. I would agree with you on not spending $200 for new woofers, but I don't know how the Goldwoods compare to the originals.
Kent

[Mystery]

Thanks for info Kent. I'll check links and try cheap caps on these.

The replacement woofers are Goldwood GW-8028 with butyl surrounds: http://www.parts-exp...tnumber=290-355
I'm not sure how close these are with the original OHM L's woofer.
From what I read, the original woofers had very large magnets.
Is there a way to improve these woofers by adding weight on the cone or in any other way?
Thanks
Edit: My OHM L's look like these...

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[JKent]

One of the surrounds is pinched under the gasket, so you should fix that.
The Goldwoods have good reviews on PE but they are apparently more suited to sealed enclosures, not ported ones like the Ohms. Someone more knowledgeable about speaker design may be of help here. The PE page, under Q&A does recommend other woofers. Or try suffing a sock in the port and see if the sound improves.
Kent

[Mystery]

One of the surrounds is pinched under the gasket, so you should fix that.
...Someone more knowledgeable about speaker design may be of help here. The PE page, under Q&A does recommend other woofers. Or try suffing a sock in the port and see if the sound improves.
Kent

I thought that too and tried to pull the surround out, but it won't come out.
I don't want to tear it.
May be it's glued or something on the basket. I'll take it out and check again.

Sound is good like this but just wondering if there are ways to make this woofer match original spec.
Thanks again.

[JKent]

I would take out the 4 screws then try to pry up the fiber gasket but you're right--it may be glued. Don't know about matching the original spec but as I said you could try stuffing the port and see if that's better or worse.
Kent

[Mystery]

I took the speaker out and saw the rubber is twisted on the side of screw hole.
Gently pulled it and it's better but it won't be perfect.

BTW, I used online calculator for cubic ft for the replacement woofer and got 23 cu. ft for ported enclosure.
I think I'm doing something wrong. It says the qtc value has ERROR. How do I get correct qtc for this woofer?
Specifications: •
Power handling: 65 watts RMS/90 watts max
• VCdia: 1-1/2"
• Le: 0.5 mH
• Impedance: 8 ohms
• Re: 7.2 ohms
• Frequency range: 35-2,500 Hz
• Fs: 36 Hz
• SPL: 84 dB 1W/1m
• Vas: 1.54 cu. ft.
• Qms: 3.9
• Qes: 1.21
• Qts: 0.92
• Xmax: 2.5 mm
• Dimensions: Overall diameter: 8", Cutout diameter: 7-1/4", Depth: 3-5/8".

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