I must be living right ......

[SEAWOLF97]

remember this old thread ??

Perfect Speaker? Let's hear your vote!

and my answer was

OHM F.

(guess I haven't heard many super high ends).....

then Ken answers

There's a ghost from the past.....I have not seen a pair of those in many years.



I had only seen 1 pair in my life..They were so good , that I never forgot them. Kinda rare, and the ones for sale are torn up or unrepairable.

Well, pulled the trigger on a set today. (at about 1k under going rate)...they are in about 98 percent cosmetic and 100 percent functional.

The story goes...seller did some landscaping work for an old man. Didn't have enough for the bill. Paid in cash plus this set of OHM F's. Seller only wanted the difference that he didn't get in cash.
I called about 5 minutes after the ad went up. Seller says phone started going crazy after I called. He took lookers in order as you should.

Hauled them home and hooked them up after an inspection. WOW , I know its heresy but they dwarf the 4410's

specsP1972 - 1984 originally $900 - $3995 per paird100 - 200 watts )4 ohms 37 - 17,000z
87 dB

from the web

The Ohm F was the most popular of the first generation Walsh speakers. It used a 12'' inverted omnidirectional driver operating from 35 - 17,000 Hz. The Ohm Fs were internationally recognized as ''one of the best...if... not the best...speaker in the world''. It received reviews from as far away as Australia and Thailand as well as throughout Europe and America.

pics

[briang]

Awesome story Seawolf.

I've not seen a pair of Ohm speakers in 25 years. Nice find.

[SEAWOLF97]

Awesome story Seawolf.

I've not seen a pair of Ohm speakers in 25 years. Nice find.

Oh yeah , he said (fwiw) that the old man told him that he had them restored before putting them in storage. With all drivers working perfectly, I guess I believe him.

[clmrt]

So, what you see is the back side of a seriously deep, down-firing 12" driver cone?

And that's all there is to it?

[SEAWOLF97]

So, what you see is the back side of a seriously deep, down-firing 12" driver cone?

And that's all there is to it?

not really. they radiate in waves off the back side of the cone, which doesn't move. read up on ohm walsh design , really quite innovative.

http://www.ohmspeakers.com/coherentlinesourcedriver.cfm

[loach71]

I have an original set of Ohm F's. They are an interesting speaker.
Make sure you get a power amp with huge current drive capability -- these speakers have some nasty impedance troughs.

Have fun with your new toys.

[SEAWOLF97]

So, what you see is the back side of a seriously deep, down-firing 12" driver cone?

And that's all there is to it?

heres the real answer , from eBay guides ...


A short course on these amazing loudspeakers. I will try to limit my comments and just hit the highlights since there is so much depth in the subject of speakers in general.
Theory: The Walsh speaker, actually introduced in 1973 / 74 (I sold the first pair to be sold locally to an architect in SF back then) is based on transmission line theory. Briefly the concept is that the acoustic wave generated by the driver, travels down the tapered cone and terminates in the resonant cavity (bottom enclosure) with no reflections running back up the cone [and therefore not out into the room either], i.e standard transmission line theory. Note that the speaker is faced down toward the floor, with the driver sitting on top at the narrowest part of the cone and the wide end of the cone is at the bottom coupled to the sealed enclosure. The radiating surface is then the backside of the cone when compared to a 'standard' speaker and thus radiates an omnidirectional wavefront [i.e. 360 deg] out into the room. That was a unique design concept and was patented by Lincoln Walsh and is major factor in the incredible aural imaging qualities these speakers have. It is a real shame he did not live to see it become reality. Further unique characterisitics are, these were the first and only speaker of the day to be (a) phase coherent and (b) without passive or active crossovers, the crossover was in the construction of the cone itself. Later KEF and other manufacturers, like those utilizing air-motion-transformers and flat panel electostatic technology, imitated "time alignment" by staggering the conventional outward facing speakers in an attempt to achieve the same effect. [Note: electrostatics actually do achieve good time alignment but suffer from narrow spacial imaging] The Walsh was the one true phase coherent speaker and was achieved by a simple and ingenious technique: The slope angle, or taper, of the cone was calculated such that the wave traveling down the cone face was in phase with the acoustic wave emminating out into the room, thus achieving phase coherence. In other words the resulting wavefront [radiating into the room] was in coincidence across the spectrum. That brings us to the crossovers, or actually, lack thereof. There are 3 sections in the long vertical cone, arrived at after long and laborious testing. The high frquency material is a titanium alloy (which contributed to their high cost, and ultimately their being pulled off the market as being too costly and labor intensive to produce), the second is stainless steel for the midrange and the 3rd is heavy paper cone material for low end. The high frequencies radiate outward at the top, titanium (smaller diameter) end, the midrange from the stainless section, and the bass at the lower paper part of the cone. This speaker was hailed as having the smoothest frequency response of any speaker (+/- 4dB down to 20Hz) in that era. By the way, prior to Ohm Acoustic launching the Model F, they launched the humongous Model A, which I have never seen or heard [but would love to] other than in print. The responder who mentioned the point about how power hungry the F's are is correct. It should also be pointed out that an amp with very high damping factor is also a big plus, in that the speaker mass on loud low end passages needs heavy dampening to keep it from "ringing" and will result in making that beautiful musical bottom end really come alive, not just a whump, so common in today's systems.
Cautions: One important point, be very careful in chosing an amp for these speakers - they hate DC (e.g. driving the amp into flatline distortion or DC generated during power on/off). Any direct coupled output amp can easily destroy these drivers, they seem to be hyper-sensitive to DC. I have been driving mine since 1977 with 2 MC 275's tube amps, each strapped for mono. With the transformer coupling on the outputs of the MC's, I have never blown a driver, even though I have driven them into distortion many times. Other people I know with Direct Coupled amps have blown the drivers and I believe you cannot get replacements anymore. [I wonder how many F's are still out there making music?]
Repair: I did replace the surrounds a few years ago. I bought a set from a vendor in Audio Mag for $20 and they worked just fine. It's a job that requires a day and a no-hurry mindset but is not technically hard to do. The most important part is the positioning of the new surround on the cone before it's glued AND the positioning lower surround to the speaker frame before it's glued to make sure the alignment of the cone inside the voicecoil is perfect. If it is not done right, piston coil will rub inside the driver and then you'll have real problems. I used masking tape, after applying it to my jeans to take some of the stickiness out, for temporary attachment until the correct position was found. I tested postion by gently pushing the cone up into the voice-coil several times to ensure free, easy movement. I rechecked this as I progressed. Once postioned correctly I used contact cement for an adhesive. Let the cement cure overnight and you are done. Take your time in removing all the old glue and gunk too. Doing good prep is essential and it is the most time consumming part of the job. Feel free to contact me if have further questions/comments. Btw, surrounds are easily found on the web these days.
Placement: Back in the 'good old days' when I had the perfect listening room for these, the ideal set up I found was the following. An ideal room will be about 12 - 15' across the front wall. Place each speaker in the left & right corners but pull them out about 1 foot from each wall diagonally [1 foot to the back and 1 foot to the side] making sure they equidistant from each surface, play with this distance until you find a sweet spot, which will be dependant on the acoustics of the room they are in. At some point, the imaging will come alive and you'll see what all the hooorah is about. Oh yea, one other thing I did but you probably won't want to do, I drilled two 1/2" holes cattycorner in the bottoms of the enclosures and ran a two 1/2" x 6" lag bolts in each speaker down into the hardwood floor - really improved the bass, didn't help the home value so much tho'.... [but they never got stolen either!]
[CV: I have been in the pro audio/video industry for over 35 years, designed/built and maintained many recording facilites and custom consoles and equipment for some the best known performers.]

The Ohm Walsh is a unique speaker that uses the infamous Walsh driver. Unlike a typical dynamic speaker, which uses a cone firing directly into the room, the Walsh driver works by exciting (or energizing) the surface of the driver itself. Lincoln Walsh theorized that a dynamic speaker could never behave like a true "piston", so instead designed his driver to radiate sound by exciting the driver's suface. The lower the frequency, the more of the driver's surface is utilized to radiate the sound into the room. The Walsh driver, most visible in the Model "F", appears similar to a cone driver firing directly into the cabinet, though on the "F" it is considerably larger than most drivers and manufactured using varying materials along the drivers length.
The Walsh driver results in an omnidirectional soundstage, particularly at lower frequencies, that is unique relative to more conventional speakers. Later Walsh speakers used a conventional tweeter, typically a cone, with a crossover to supplement the high frequencies; this radiates into the center of the room when facing the speaker (nominally 45 degrees off center when facing the speaker). Walsh switched from a trapezoidal wood cabinet using real wood veneers to what are referred to as "sound cylinders" to reduce manufacturing and selling costs.
Why such a loyal following on E-bay for the Ohm Walsh? Several. First, these speakers are very unique, both in terms of appearance and sound, relative to "conventional" dynamic speakers. While Ohm is no longer the only manufacturer to make speakers using the Walsh driver, the others doing so now are esoteric, small volume (read: expensive) producers.
Second, Ohm is rather unique in that they still support their entire product line, including crediting the full retail price of the original model towards purchase of a new one. Replacement parts and upgrades are available for their entire product line through their website. How many speaker manufacturers today provide that level of service and support?!
Third, the soundstage provides what Ohm refers to as "full stage stereo"; unlike conventional speakers, the soundstage is very wide and largely independent of the user's position relative to the location of the speakers (in large part because of the omnidirectional driver coupled with the controlled directivity of the tweeter on later models). Personally, I find the effect very appealing. They even work well in a home theater set-up without a center channel, operating with a "phantom" center channel...try that with conventional speakers (the soundstage will often collapse to the speaker you are sitting closest to)!
Issues to look for include the speaker cabinet (the wood veneers used on these models is prone to chipping, as they have sharp, exposed edges, particularly on the lower edge of the cabinet), "foam rot" of the surround (buzzing present, particularly at low frequencies), dented "cans", and improperly repaired or inoperable drivers. Ohm claims that the original Model "F" driver, rather complex in terms of materials and construction, cannot be properly repaired (Ohm does offer other, more modern Walsh drivers that can be utilized in the original cabinets). The grills are often damaged and discolored, though Ohm does offer replacements. Finally, the speakers are rather large and heavy, requiring careful handling and packaging to avoid damage in shipment (Ohm recommends removing the drivers, packing and shipping them separately from the cabinets to reduce risk of damage).

[SEAWOLF97]

So, what you see is the back side of a seriously deep, down-firing 12" driver cone?

And that's all there is to it?

I was wrong in my first reply to this. The cone does move. It is a 12 in , firing straight down into a 4.3 cf sealed cabinet filled with batting, covered with cloth to keep it from going all over when you remove the driver.
The speaker , of course , has no crossover. The top section that radiates HF is titanium (even more expensive in 1977) , then lower on the cone is stainless for MF and then lower is paper for LF. I was kinda freaked, looking at horizontal depressions all around the paper. OHM's president assured me that they come from the factory that way and these were position calculated for dampening.

Have been doing fuse testing last 2 days and now they seem very stable on 3A. (they shipped with 4A)

[Robh3606]

Hello SEAWOLF97

Scanned this out of my 1975 Audio Hi Fi Handbook. Thought you might like it.

Rob

[Ian Mackenzie]

Awesome story Seawolf.

I've not seen a pair of Ohm speakers in 25 years. Nice find.

The Ohm www site is quite interesting too.

I wish Storm would change seasons as these posts have tarnished an otherwise interesting and informative thread.

Seeing as you are so well read and worldly I wonder if you can tell us all what an Ameri-Can is? For a clue to the correct answer I highly recommend you watch the movie "Kenny". He (Kenny) is the Real Deal a far as a role model for you is concerned.

http://www.kennythemovie.com/indexFlash.html

[perrydu]

$135???????? You make me sick!!!! I bought a pair of F's in 1976 and a long series of events, including blown drivers, theft, handmade cabinets, ebay purchases and repairs leave me with a pair that still sound great. There is a rough looking pair on ebay right now starting at $750, but no bids. Another pair being offered mentions with surprising honesty the smoke that came from the voice coil at one point. The tempting offer on ebay right now is a pair of OHM A's. These are extremely rare and supposedly even better than the F's. They do not work and I would be afraid to risk $1000 on the chance that I could get them fixed. I had my F's refoamed at Audio Atlanta and have been quite pleased with the work. OHM claims they cannot be repaired properly but mine seem pretty close to the original sound. I drive mine with a Carver M400, I really don't know the damping factor for it. The F's supposedly need a factor of 8 or above.

[SEAWOLF97]

The tempting offer on ebay right now is a pair of OHM A's. These are extremely rare and supposedly even better than the F's.

Those A's are 18 inch !!! Must be huge cabinet.
Still searching for the right power source for mine. Have hooked up 4 different receivers with varying degrees of success.

[perrydu]

I started with a Technics receiver that had 100 watts per channel but later switched to the Marantz 2325. It sounded great but the whole system was carried away by a burgler. I got the Carver M400 which supposedly puts out about 200w/ch and have been happy ever since. I blew two drivers with the Marantz but the Carver has some sort of speaker protection built in. I trigger it regularly when I try to play something with a lot of bass. I have been driving F's for 20 years with the Carver without any further driver damage. I am afraid to switch amps and risk blowing out the speakers. Certain recordings really stand out on these speakers. There is a song on the Heart "Little Queen" CD that starts with the sound of people tossing coins as to a street band. With the F's properly positioned you can point to the exact spot where the coin lands. My favorite is "World Machine" by Level 42. It really showcases the range of these speakers.

[SEAWOLF97]

$135???????? You make me sick!!!!

heres a cheap pair on da bay

Starting bid:US $2,450.00

http://cgi.ebay.com/ws/eBayISAPI.dll...3313&rd=1&rd=1



is that SICK , ,,,, new or old version ??

OLD VERSION OF SICK

Pronunciation: 'sik
Function: adjective
Etymology: Middle English sek, sik, from Old English sEoc; akin to Old High German sioh sick
------------------------- --------------
1. Not feeling good.

2 a (1) : affected with disease or ill health : AILING (2) : of, relating to, or intended for use in sickness <sick pay> <a sick ward>

NEW VERSION

Now used as the newest word to replace cool. Something that you've never seen before.
Old version:

Mary,"I feel sick to my stomach".

Jess,"Ask the teacher for a Nurses' Pass".

New Version
Keegan:This Calculator is sick!

Kass:That outfit is sick!

[SEAWOLF97]

The tempting offer on ebay right now is a pair of OHM A's. These are extremely rare and supposedly even better than the F's. They do not work and I would be afraid to risk $1000 on the chance that I could get them fixed.

SOMEBODY PULLed the trigger on them at $1000 BIN.