OHM Acoustics "Walsh F" Speaker remakes

Hi,

Bud, the weblink you posted only goes to the Picasa home page, not to your pictures.
I'm still looking forward to seeing more of your work. I haven't yet had time to EnABL any of my drivers, but I have most of the tools and materials. When I get to this Walsh clone project, I'm still thinking of Mamboni's mods on one side of the Pioneer driver and yours on the other, unless you think EnABLing both sides might be better.
I appreciate the time and effort you have put in on your work and in helping others on this forum. I hope you reap some well-deserved financial rewards from it too.

Take care
berm
 
Berm please contact me

Berm you out there? Please contact me re:

It occurred to me while watching this thread that this - Mamboni’s DIY omni - may be just the ticket for a great mono speaker. I’ve been looking for something that would provide great sound for 78’s and mono LP’s, and provide it over a wide area. No beaming speaker wanted for this. The one difference I think is that here an omni tweeter, or tweeter array, would be desirable in this case.
 
You could use the Pioneer woofer and one of the Radio Shack Linnaeum dipole drivers. When EnABL'd this is a sensational tweeter to 13 kHz.

I use a pair per side on my reference system and then slope a Pioneer piezo film, half can tweeter, always on ebay, for the 13k and up air.

The efficiency would balance nicely with the woofer and the RS dipoles are inexpensive when you can find them.

Bud
 
Just some more information for inspiration. I heard this at the London Audio and AV show last weekend. Check out:

http://www.rountree-acoustics.com/

Very promising, very clean and great bass. It sounded much more natural than most of the other product there.

The enclosure is worthy of attention. The driver is coupled straight to the floor with a steel rod and the low mass foam board enclosure kind of hangs off the driver, certainly different, and it seemed to work very well.
 
OHM Walsh Sound Cylinders

Here are some shots of some OHMS that I repaired back in 1999. The ABS "bulkhead" that the drivers were mounted on was broken, probably due to being dropped. (ABS pipe cement-resin repairs this nicely)
 

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OHM Walsh Cylinder

Here is a shot of the full systems in my stepsons old room along with my AL1. FYI both the OHMs and the Allisons were found at the old Jacksons Flea Market (Hadley MA). Each pair was less than 100 bucks in '98. Of course they both needed work. As I mentioned in my first post that both OHM systems required the broken ABS driver mounting bulkhead to be fused together with with ABS pipe fusor. The perforated metal "cap" had the grill cloth stretched over the cap and then pressed into a recess in the bulkhead. Very difficult to remove. I left the cloth off. They looked fine with a new coat of black paint. The AL1 needed new foam surrounds and some of the leads to the mid and tweeter units had been broken. Careful soldering brought them back from the brink.

-T
 

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adason said:
teknofosssil,

having inductors so close to the woofer is probably not a good idea

ed

You may be right. Based on photos of the insides of other OHM Walsh canisters there are quite a few other models that are constructed the same way including the Walsh 5. All I can say is that it must not have a negative effect on the sound. Many like the sound of the various OHM models.

My friend Glen that has these systems said that they are still going strong and he is very happy with the sound. He has had them in operation since 2000 if I remember right. They don't have foam surrounds so I'd guess the weak part of the system is the electrolytic caps. (and those usually last long than foam surrounds) -T
 
Re: OHM Walsh Cylinder

teknofosssil said:
Here is a shot of the full systems in my stepsons old room along with my AL1. FYI both the OHMs and the Allisons were found at the old Jacksons Flea Market (Hadley MA). Each pair was less than 100 bucks in '98. Of course they both needed work. As I mentioned in my first post that both OHM systems required the broken ABS driver mounting bulkhead to be fused together with with ABS pipe fusor. The perforated metal "cap" had the grill cloth stretched over the cap and then pressed into a recess in the bulkhead. Very difficult to remove. I left the cloth off. They looked fine with a new coat of black paint. The AL1 needed new foam surrounds and some of the leads to the mid and tweeter units had been broken. Careful soldering brought them back from the brink.

-T

If anyone is looking for a set of the OHM Sound Cylinders there is a set on EBAY. The auction number is: 290266408368. The set that I repaired had fabric surrounds on the full range drivers. So even at 18 or so years old that is one thing that won't need to be replaced. One thing I didn't mention about the SCT is the tubular cabinet. It is a pretty thick walled tube (perhaps 3/8") with a sheet of lead around the inside to deaden the structure. There is also some sort of polyfill like material and the cabinet is of the vented type.

When I had these speakers I did nothing other than repair the systems. No mods were performed. However, if I was to modify this unit I'd loose the inexpensive cone tweeter and replace it with a better quality device (like the BG Neo 3PDR planar tweeter) and loose that carboard reflector, possibly using some acrylic damped with some lead sheet or modeling clay heated and then flattened out with momma's rolling pin and applied the the reflector (you needn't tell momma what we borrowed her rolling pin for.... my wife never uses hers anyway). The BG tweeter would have to be adjusted for correct response (series capacitor and possible a level control) to blend it with the inverted cone woofer. (oh, sorry I mean "Walsh driver".)

-T
 

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question of alignment

Photo #3: Closeup of head unit: Walsh woofer driver with top mounted tweeter

I do not have access to a scope any more and cannot perform accurate pulse/time analysis to determine proper tweeter alignment with the main driver. What I do now is get a friend to move the driver back and forth slowly, with a pink noise signal running through the nearly completed system. When the sound from the two drivers "merges" as one apparent sound (with my eyes closed) that becomes the mounting position. It works surprisingly well and the distances are reproducible between identical driver types.

Do you have a better way to do this?
 
unabl?

Hi Bud, the main driver certainly would be possible. However, I was thinking about using these for the HF driver. Any experience with the monopole AMT's? You and I both have a love of the Linneaum drivers, have you patterned those?
Mine are long gone.
 

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