canuckaudiog
On a quest for high fidelity
Question for you guys. How challenging is it to refoam a pair of Walsh Ohm F's?
Refoaming Walsh Ohm F's - Tough to do?
- Thread starter canuckaudiog
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marantzfan
...
Last i heard, only one Guy on the planet did it right.....
sealy
Addicted Member
It is challenging, but can be done. You need a 12 in. surround and it has to be stretched almost to the breaking point to get it around the cone. Once it is on, it has to be very carefully positioned, more so that most other woofers, so the utmost care is needed. The surround is one problem, but spider sag is another you will probably have to deal with. That cone is very heavy and virtually all F drivers develop spider sag over time. The voice-coil on the F driver is quite small, therefore even a little sag will cause the voice-coil to drop partially away from the pole piece, with a concomitant drop in response. A new surround will help mitigate that problem to a degree, but the spider may have to be replaced, if the sag is significant. That can also be done, but I sure as hell wouldn't attempt it. Leave that to the pros. The best way to delay spider sag is to turn the drivers upside down when not in use. That procedure will help a sagging spider settle back to the correct position.
My Fs were refoamed by a friend and they worked well. If you are reluctant to try it, I would suggest calling Vancouver Audio Speaker Clinic. The guys there have refoamed many pairs of F drivers with great success. If nothing else, they will gladly give you advice on how you can do it yourself.
My Fs were refoamed by a friend and they worked well. If you are reluctant to try it, I would suggest calling Vancouver Audio Speaker Clinic. The guys there have refoamed many pairs of F drivers with great success. If nothing else, they will gladly give you advice on how you can do it yourself.
frommerstop
Super Member
Also be on the look out for foam deterioration inside the cone. That's the part that Ohm claim is the most difficult to replace correctly (the reason main they no longer service them), and makes a big difference in the final sound.
audiomagnate
Addicted Member
Spider sag is no big deal. Just replace the spider. Almost all speakers of this age need new spiders, which become brittle, and also experience adhesive failure. I say go for it!
Ohighway
Wannabe Minimalist
According to -him- no doubt....
Yeah, all the Fs sag over time.
I have a very hard time taking any of their claims seriously.
:thmbsp::thmbsp:
frommerstop
Super Member
Whether you take the manufacturer's claims seriously or not, I've seen the foam inside become very brittle & crumble off. Looking at how they work, it's apparent that the type, and consistency of that dampening IS important to the quality of the Walsh driver's sound. I'm not convinced that simply "sticking some padding" on the inside (or removing it all together, as I've seen done) would yield a speaker that sounds like the original... I'd even go so far as to assert that it won't.
loquatious
village elder
read this, from HHR Exotic speakers. the only folks who can properly rebuild these.
http://www.hhr-exoticspeakers.com/documents/Ohm F and A.pdf
.
http://www.hhr-exoticspeakers.com/documents/Ohm F and A.pdf
.
canuckaudiog
On a quest for high fidelity
Thanks for the responses guys.
What an exotic speaker! There's a gentleman who has a pair and is inquiring about refoaming them so hence the question. I kinda want to see it through just to hear these suckers..
What an exotic speaker! There's a gentleman who has a pair and is inquiring about refoaming them so hence the question. I kinda want to see it through just to hear these suckers..
frommerstop
Super Member
I've heard a few "restored" Fs, and none of them seemed to sound the way I remember them "back in the day". Some sounded very good, but just didn't seem as "right" as the original... especially in the upper mids & highs. Not sure how much that has to do with my memory, or with the quality of the restorations, but it's kept Ohm Fs at arm's length all these years. I'm intrigued by HHR's work, and I'd love to hear one of theirs, but they are a bit too pricey for me.
Kneedeepinit
Super Member
are these the ones that sold last week as part of a stereo for $500? The price was so good I assumed it was a scam.
I sent an email anyways and , despite replying 21 minutes after the posting, I was too late.
I sent an email anyways and , despite replying 21 minutes after the posting, I was too late.
sealy
Addicted Member
A very comprehensive article on the F driver. Best I've ever seen. What was left unsaid is the cost of rebuilding a pair of vintage F drivers. No doubt it is extremely costly. The article is a testament to Lincoln Walsh and clearly shows how far ahead of his time he was in terms of transducer design. I'd love to acquire a pair of HHR speakers one day.
bshorey
Super Member
On the level of difficulty of refoaming speakers scale, put the F's on the high end.
I had conversations with Dale at HHR when mine needed new voice coils. I think our signals got crossed somewhere, because I was under the impression that he needed the cabs, etc, and would only make significant upgrades to the system, or something like that. More than I was ready for at the time. Later, he contacted me and indicated that he does do some level of repairs and refurbishing of the originals, so you should consider talking to him.
I ended up building plywood boxes for my drivers and shipping them off to The Speaker Exchange, in Florida. They replaced the voice coils and refoamed them for $350 each.
They sound superb to my ears. Definitely worth doing, original F's are becoming rare and are still stunning after all these years.
I'd love to hear some of HHR's work. Someday...
bs
I had conversations with Dale at HHR when mine needed new voice coils. I think our signals got crossed somewhere, because I was under the impression that he needed the cabs, etc, and would only make significant upgrades to the system, or something like that. More than I was ready for at the time. Later, he contacted me and indicated that he does do some level of repairs and refurbishing of the originals, so you should consider talking to him.
I ended up building plywood boxes for my drivers and shipping them off to The Speaker Exchange, in Florida. They replaced the voice coils and refoamed them for $350 each.
They sound superb to my ears. Definitely worth doing, original F's are becoming rare and are still stunning after all these years.
I'd love to hear some of HHR's work. Someday...
bs
canuckaudiog
On a quest for high fidelity
Yep, that would be the one. He got a Dual 1219 and something else thrown in as well. Quite a deal.
frommerstop
Super Member
I think they generally quote on an individual project basis, but I believe they are charging around $5000 pr for just driver restoration of a customer's set. A fully functional par of speakers start around $7500, and with custom cabinets, and "upgrades, they can be as much as $12,000! They may be worth it, but if I were going to drop that much on a pair of speakers, it'd be a new pair of Quads.
W9TR
Super Member
I just finished a complete Ohm F restoration project, and am listening to these incredible speakers as I write this. I owned a pair in the 70's and wanted to see how a pair would stack up to more modern loudspeakers. I found a cosmetically and structurally perfect pair for refurbishment locally.
I researched all the available options.
The first option is Dale at HHR exotics. Dale is hugely helpful and knowledgeable. For $7000 he'll remanufacture your existing Ohm F's, bases and all. That includes a completely new pair of drivers and extensive mods to everything else. He didn't offer a driver only refurbishment when I spoke with him, and I didn't want to ship my perfect bases and chance shipping damage. Besides, 7 big ones was more than I had to spend for what was a bit of a nostalgic journey.
The second option is Speaker Exchange. They offer reconing and recoiling services, but don't touch anything else on the drivers. The interior foam and treatment on the Ti section has to be dealt with, along with all the RTV in the slits on the paper cone section.
The third option was the one for me. I reached out to Bill Legall of Millersound, and he agreed work on my drivers if I would deliver them to his shop in person so we could discuss what needed to be done after he inspected the drivers. He only does one or two pair a year due to the difficulty. So I headed to Philly with the drivers to discuss options with Bill. Based on their overall very good condition, we agreed to a complete refurbishment. This included new custom voice coils on Kapton formers, solid silver wiring relocated to the top spider, reconstruction of the internal cone treatments, new spiders and surrounds, and significant structural strengthening and dampening of the driver assembly.
I re-wired the cabinets with Kimber 4TC and added new beefy connectors on the bases. I re-did the damping material. Five coats of hand rubbed Teak Oil and dry cleaning the grills, and the speakers glow.
I'll post some pix soon. The sound is as I remember it, only better, probably due to better electronics. Mr. Legall says I need to break em in for 60 hours, all of which will be a pleasure.
Tom
P.S.
You can not just replace the spiders and surrounds. The Ferrofluid used in the originals leaked out and attacked the adhesive between the VC and cone, causing almost 100% failure rate over time.
I researched all the available options.
The first option is Dale at HHR exotics. Dale is hugely helpful and knowledgeable. For $7000 he'll remanufacture your existing Ohm F's, bases and all. That includes a completely new pair of drivers and extensive mods to everything else. He didn't offer a driver only refurbishment when I spoke with him, and I didn't want to ship my perfect bases and chance shipping damage. Besides, 7 big ones was more than I had to spend for what was a bit of a nostalgic journey.
The second option is Speaker Exchange. They offer reconing and recoiling services, but don't touch anything else on the drivers. The interior foam and treatment on the Ti section has to be dealt with, along with all the RTV in the slits on the paper cone section.
The third option was the one for me. I reached out to Bill Legall of Millersound, and he agreed work on my drivers if I would deliver them to his shop in person so we could discuss what needed to be done after he inspected the drivers. He only does one or two pair a year due to the difficulty. So I headed to Philly with the drivers to discuss options with Bill. Based on their overall very good condition, we agreed to a complete refurbishment. This included new custom voice coils on Kapton formers, solid silver wiring relocated to the top spider, reconstruction of the internal cone treatments, new spiders and surrounds, and significant structural strengthening and dampening of the driver assembly.
I re-wired the cabinets with Kimber 4TC and added new beefy connectors on the bases. I re-did the damping material. Five coats of hand rubbed Teak Oil and dry cleaning the grills, and the speakers glow.
I'll post some pix soon. The sound is as I remember it, only better, probably due to better electronics. Mr. Legall says I need to break em in for 60 hours, all of which will be a pleasure.
Tom
P.S.
You can not just replace the spiders and surrounds. The Ferrofluid used in the originals leaked out and attacked the adhesive between the VC and cone, causing almost 100% failure rate over time.
canuckaudiog
On a quest for high fidelity
Wow.
What a journey for a pair of speakers. Must have been worth it though. I think it will be a very long time before I ever consider owning a pair of those, talk about a challenge and a half. Dang.
I can't wait to see pictures. And please post your listening impression, I'd love to hear vicariously what these babies are like.
sealy
Addicted Member
You must have encountered the white "goo" in the voice-coils that I found? I assumed that was congealed ferro-fluid.
W9TR
Super Member
The original VC's did have some white goo, which I assume was what was left of the adhesive they used to adhere the VC to the former and the former to the cone. I don't know for sure, though.
The ferro fluid was a brownish color. Gravity caused it to flow (or get pushed) out of the gap. The organic binder in the ferrofluid apparently was a solvent that attacked the adhesives. Both my original F's failed at the VC-cone interface. Among other places!
Tom
The ferro fluid was a brownish color. Gravity caused it to flow (or get pushed) out of the gap. The organic binder in the ferrofluid apparently was a solvent that attacked the adhesives. Both my original F's failed at the VC-cone interface. Among other places!
Tom
W9TR
Super Member
I'm about 60 hours into the rebuild, and the F's have really opened up and are sounding great - better than I remember my first pair sounding 'back in the day'.
Here's a thread with some pics.
http://www.audiokarma.org/forums/showpost.php?p=6235071&postcount=1
Tom
Here's a thread with some pics.
http://www.audiokarma.org/forums/showpost.php?p=6235071&postcount=1
Tom
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