HI,I AM LOOKING TO REFOAM MY OHM F'S MYSELF.I WOULD APPRECIATE ANY HELP IN LOCATING A CORRECT, OR A SET THAT WILL WORK OF FOAM SURROUNDS.ONCE AGAIN,ANY HELP WILL BE GREATLY APPRECIATED!.THANKYOU,STEVEN. |
Mbiker: I had a very well known "professional speaker repair facility" refoam a set of my F's years ago and they did the same thing. It caused the driver to bind up, resulting in much lower spl capability and limited low frequency output. I had to pay another "professional speaker repair facility" to disassemble the freshly glued ( non-brittle ) surrounds, which did result in damage, and re-install the proper surrounds in the proper fashion. After all of that, this set ran fine after all of the repairs, but not quite as good as my first set that i also still have.
With all of that in mind, refoaming an F is a tough job. MUCH tougher than a standard woofer. For one thing, you can't get around shimming the voice coil with these. Due to the length and mass of the cone, the driver tends to "wobble" in the gap. ANY type of binding due to a lack of centering of the voice coil WILL result in quick driver failure. This in itself isn't a big deal, but looking at the F will tell you how "not easy" it may be to get a shim into the necessary area.
As part of installing the shims, you're likely to encounter the foam damping material that is installed on the INSIDE of the Walsh cone. This foam is probably relatively brittle and may crumble when physically "brushed" as you try to install the shims. The loss of foam will change the resonant, transient and damping characteristics of the driver. Obviously, extreme caution needs to be taken here.
Besides that, you really need use the proper density foam surround for this driver. Due to the aforementioned length and mass of the driver itself, and the way that the driver is mounted on the baffle, the surround acts as a major portion of the suspension of the speaker. Compared to a standard driver that fires horizontally, the surrounds on the F's are working WAY more than "double duty". Use the wrong surrounds and the suspension will either be too stiff ( causing driver binding and a lack of output ) or too soft, with a lack of damping and excessive ringing.
From what i've been told and probably due to some of the reasons listed above, most "professional speaker repair facilities" consider the Ohm F to be the toughest dynamic driver to properly refoam.
With the above info, you may be able to make a more informed opinion of whether or not you are up to to tackling this type of a task.
Other than that, the amount of TRULY "deep" bass that these speakers are capable of is pretty astounding, isn't it? When you say "5 Hz", most people will think that you're joking or exagerating. Those of us with F's that are really working well know exactly what you mean though. I know this because the Ayre Acoustics disc starts off at 5 Hz and my F's are "pumping away" at great amplitude. Enough to shake the house like you wouldn't believe. Sean
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PS... If you want to drop me an email, i can share with you a few competent speaker repair facilities and one to avoid like the plague. |
I just purchased a set of refoamed ohm "f"s, (from a member here...) and found one of the problems..
One speaker will drive down to visible , say 5hz, cycles, producing thumps on the Pink Floyd "dark Side" album that have to be heard to be believed. The other, however, while sounding fine at all other frequencies, can't handle the Floyd. I took a close look at the surrouds, and discovered that the surround on the poorly performing speaker is glued too low on the cone, limiting the travel of the voice coil.
Now, do i attempt to fix it myself??? I've done regular woofers without a problem.. |
Hififile, thanks for confirming my previous statements. I'm glad that you took the same stance that i did as far as saying it all boils down to enjoying the music.
My main problem with the whole "Ohm ordeal" is that they are marketing their current products as having Walsh drivers and they are not Walsh's as we know them. Other than that, these speakers may do everything that someone is looking for. However, I did feel it necessary to state that those that were familiar with the original Walsh based products might feel let down by Ohm's current offerings. Given the amount of time that has passed and the technology that has accumulated, they have done little to nothing to improve upon what was already an excellent design.
As i've tried to make clear before, i try to limit my input here to personal experience or information based on reliable sources. While i've seen the insides of the speakers being discussed, the digital photos that i had came from another source. If i was to pass on information from someone else, i would only do so if i felt they were reliable and the information was verifiable. Obviously, sharing someone else's opinion or subjective findings is done strictly as a contribution to a conversation. It should never be taken as "gospel" that everyone should hold or share that point of view.
Please don't take this to mean that i'm saying that i am always right ( far from it ). Like most others here, I do try my best to be as accurate as possible. If i am wrong or overlook specific aspects of a situation, i always ask that people more familiar with the situation correct me. Not only do i not want to screw something up for someone else, i want to know so that i don't continue to pass on "misinformation".
Hopefully, none of us are above being corrected or have stopped learning from each other. Sean
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Dear Unsound, 7p62mm, and Sean,
I worked in hifi in the 70's and owned 2 very successful stores in the late 70's & 80's. We were big ohm dealers and sold, and repaired lots of their products. I also know John Strobeen personally and own some of his current speakers.
Sean is exactly right, as usual!
The current line uses conventional cone and dome type speakers. The woofer is inverted down towards the floor. The speakers can sound great providing the room and rest of the system are all working well together.
What matters is that you are happy with your music! The good part is tha John will let you try the speakers in your home, and return them if not happy. He is a true gentleman, and a man of absolute integrity!
I use other speakers that I prefer right now, but the ohms are worth worth an audition. (My dad is using the ohms and he loves them!)
Best Regards, and Happy Listening,
Hififile |
Sean,
Maybe what looks like a 'conventional' woofer is actually some new type of driver. A conventional woofer and tweeter would not produce the sound that I get from my speakers. As I've stated previously I don't see how the imaging could be improved. Perhaps the older models are better as you state.
Regards,
7p62mm |
Funny, refurbishing my trusty old Ohm C-2's for my HT system about six months ago is what pushed me toward "rejoining" the higher end audio world after a long absence and assembling a separate system. While the C-2's do not have a place in a high-end system, they are very, very nice in their proper place. |
7p62mm, i wish i still had the digital pictures of what the insides of those "cans" looked like. I'll just say that i'm NOT "guessing" at what is inside of them.
I have also discussed this with a local dealer. Not only is he a former authorized Ohm dealer, he is known nation-wide for speaker repairs. As such, he has seen the "guts" of many speakers, including the later "Walsh" drivers. In his own words, he stated that the Walsh series used a "conventional" woofer and was not anywhere near the speaker that the A's and F's were. Knowing what was inside of them and also hearing the lack of performance ( compared to earlier models ), he had a hard time selling them. As such, he dropped the line. I think that this may be a large portion of why Ohm can no longer be found in dealerships.
I do have one question for you. Given the overall height of the original F driver, which is 16" tall, what kind of "Walsh" could you fit inside that little mesh "can" ? Now figure out how you're going to mount both a tweeter and crossover components inside that can. Believe me, it's NOT pretty or even well executed.
If you are feeling brave ( don't do it while "relaxing with a drink or two" ), take your "sealed can" apart. While this will affect your attitude of how you look at those speakers after doing that, it should not alter the level of respect that you have for how they sound or their presentation. If you are happy with them and what they do for your musical enjoyment, my suggestion is to STOP looking at threads like this and start listening to more music. I need to take my own advice and do the same thing. I think that we would all be a lot happier. Not only that, i could actually spend time getting things done and quit blowing so much money on stuff that i don't really need : )
Unsound, thanks for the kind words. I do what i can with what i've got. Obviously, that means that i've got too much "unproductive" time : )
I've often wondered about doing something similar to what you discuss. It is something that i will probably check into in the future. Right now, i just have too many other projects going on to consider it.
As to what model i would strive for, i think that this is obvious. I would look for a GOOD set of Ohm F's. Only problem is that many ( if not most of them ) will need an overhaul or have been physically damaged to the point of no return. The foam will have rotted, voice coils may be damaged, the spiders ( part of the driver suspension ) will be sagging, etc... As such, you would be looking at quite an undertaking should you want to take on such a project.
Most people that have these speakers or do purchase a pair have probably never really heard what they are capable of. Those that have will not part with them. Even with the less than optimum performance that they will deliver in the average installation, it has been stated about them ( and i quote from a review ) "The Ohm F is an extraordinary loudspeaker. It has only one driver, which acts as a pulsating cylinder, translating the electrical impulses of the operating amplifier into sound without disturbing the phase relationships of the impulses. What this means in terms of sound quality is remarkable. The "coherent" sound produced by this speaker is clear, full and undistorted. It may well be the finest speaker on the market, and is certainly without a doubt among the top few. It requires a tremendous amount of power to operate: amplifiers of less than 60 watts per channel are just not suitable. But given the proper associated electronics, the Ohm F is capable of providing almost absolute realism in the listening room."
Keep in mind that even most "expert" and "professional" speaker repair facilities HATE working on Walsh drivers and some won't touch them with a ten foot pole. The second pair that i bought was just about ruined by an extremely well respected and well known "speaker rebuilder" and tube gear manufacturer. Even with as poorly as the speaker was performning when he was done with it, it impressed him enough to try and design his own version of it. He is currently marketing them on a direct purchase basis and claims that they work like no other speaker.
I have since had the second set repaired but not without consequence. Needless to say, i don't have many kind words to say about the first "expert" that worked on them. I have thought about starting to repair these drivers myself, but i would first need to find a pair or two of "basket cases" to experiment with. I'm not about to "gut" the two pair that i have for the sake of advancing my knowledge of them. Sean
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Sean,
I think that you are mistaken about the design of the newer Ohm drivers. The reason that I say this is from reading Ohm's literature and from listening to the speakers. If the can was just a woofer/tweeter combination then you would not get the line source type of sound from them. That said I agree with your comments about the speaker's performance. The area where they come up short is that they won't deliver high SPL's. If you try to overdrive them then the protection circuitry will start to kick in. (This happened to me last night. I was running a high blood alcohol level and cranked it up too high). My thoughts about correcting this is to add a separate sub woofer to handle the low end. Unfortunately I can't afford to do this at present. Gold at $350 will change my life. Check out DROOY, HGMCY, and NEM. Take care bud. |
Sean, first let me say that I aways enjoy your posts. They are detailed yet succinct. You have the ability to share your impressions with out resorting to hyperbole. To the best of my limited knowldege they are acurate and technically sound. To top it all off you can write. The professionalism of many so called experts palls in comparison. Your response to a query about a classical radio station in Texas drew my awe.
Of all the various incarnations of these speakers, which are your favorites? Which ones might you suggest as worthy of a hunt? Are any of the current models a consideration?
I have been toying with idea of using these speakers set up along the long wall 50% out from the back wall, 25% out from the side walls with the listener midway and against the opposing long wall lined with some absorbing padding directly behind the listener with an all TacT system. Have you any thought on this scheme?
As always, thank you in advance. |
Unsound, 7p62mm described the newer "Walsh" series. My only comment to what was stated is that it does not use what is historically known as a "Walsh Driver". Instead, the newer designs use a conventional woofer that is loaded face-first into the top of the box. What you hear coming out of the "can" is the backwave of the driver i.e. the sound leaking out of the holes in the drivers' basket. The front wave of the downward firing woofer is vented from within the box. Since there is limited cone exposed through the drivers' basket and upper mids and treble are highly directional, they augment the woofers high frequency output with a tweeter.
In comparison, the original Walsh driven Ohm A's and later version called the Ohm F's use very different drivers from the newer versions. While both use one full range driver ( no tweeter or crossover network ) that radiates 360* horizontally and looks like a "pylon" or "road cone" mounted on top of a sealed box, the designs are quite different from each other.
The A's used a greater flare rate near the end of the cone and somewhat resemble the old horns on Victrola's. The cones were made up of two sections ( top and bottom ), each one making use of different metalic materials that were internally damped. The suspension was rubber based. As such, the surrounds do not decay and would not need "refoaming" unless ripped, etc... Efficiency on the A's was said to be in the very high 70 dB range. I'm guessing somewhere around 78 db's or so from what i've read about them. Impedance was spec'd at 8 ohms but later models were much, much lower impedance. As such, it was a phenomenally tough load to drive, especially with the amps that they had available back then. As far as i know, there are VERY few pairs of these remaining.
The F's were basically an attempt to refine the A's. The cones on the F's have a more linear taper and make use of three different materials and arranged in a top, middle and bottom section. Each material was selected for specific attributes within specific frequency ranges. There are even "slashes" that were strategically cut into the bottom section to help break up standing waves along the length of the cone. While the impedance is rated at 4 ohms nominal and 3 minimum by the factory, they actually average closer to 2.5 ohms and dip below 2 at low frequencies. Efficiency was factory rated at about 87 dB's but my experience says something closer to about 82-83 dB's or so. Once again, these were tough loads for most amps back then ( and even today ) to deal with. I have run into problems with some very well respected amps trying to drive these.
Both of these speakers take a tremendous amount of power to function at their best. I remember an old review of the F that stated "anything less than 60 wpc is just not suitable". Personally, i think that an amp that can do at least 300 wpc at 2 ohms without a fuss would be the minimal requirement. Even with that in mind, i have had amps that were rated for 400 wpc @ 4 ohms begging for mercy with these speakers. Obviously, this pushes a LOT of amps out of the equation and proves that not all amps are created equally, regardless of specs.
As to sound, both the A's and F's ( when running right and in good condition ) are known for tremendous low frequency output. I recently had a set doing FIVE Hz ( !!! ) at high output levels. It sounded like a helicopter was inside the house : )
Soundstage is phenomenally wide and deep with a very natural presentation. Notes tend to effortlessly float in the air. This is probably related to the dispersion pattern and fact that you have one driver producing all the sounds in phase with each other.
Midrange sounds very cohesive and seamless, as all the primary notes & harmonic overtones from both instruments and voice are reproduced with no crossover points or multiple drivers to disturb the signal. Highs are very crisp and clear with bell like qualities. Most of that may be attributable to the metalic section of the cone. To minimize "metalic ring" like you get with metal domes, they applied a thin layer of glue and foam inside the driver itself. Not only does this help to absorb high frequency reflections and standing waves inside the driver and box, it also damps the metal membrane.
There were quite a few revisions during the production run of these speakers. Some obvious ones were the design characteristics of the frame used for the driver. I have two sets of these and they are visibly quite different from each other. Other things not noticeable from the outside were the types and quantities of internal damping materials.
These speakers are limited in terms of SPL and dynamic range. They work best for listening at low to medium levels. They can play at higher levels, but attempting to do so for an extended amount of time will almost surely result in either the amplifier or speakers coughing up smoke. Keep in mind that i like "LOUD", so my "medium" listening level might not be the same as yours. Either way, when used within their limitations, they do some things that most other speakers can only dream about. That is why i own TWO sets of them : )
The last Ohm's that i know of that made use of what i would call a "Walsh driver" would be the Ohm G's. These were a short lived model that did things very differently from the earlier "Walsh" speakers. Not only was the height and radiating surface of the driver reduced, the materials used were quite different. Besides that, the Ohm G made use of a passive radiator design rather than a sealed box. This was obviously done to augment low frequency output but also maintain a small amount of damping for the driver. I guess that they were trying to use a smaller, lower mass Walsh to achieve greater high frequency capabilities. By doing so, they ended up losing both mass and surface area in the attempt. Both of these are major factors when it comes time to reproducing deep bass. Anything after the G is simply a "Walsh" in name for advertising purposes.
Obviously, this is just my point of view. Take it for what it is worth. If anyone is interested in further info on "vintage" Ohm's, drop me a line. Sean
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7p62mm thank you very much, yes this helps quite a bit. |
The Walsh driver handles the low end up through the midrange. It is crossed over to a tweeter for the high end. Not sure about the crossover point or what order filter it is. You will have to contact Ohm for this info. The Walsh driver acts like a line source and thus is omnidirectional. Ohm installs a piece of felt on the driver to reduce its emmission to 180 degrees. This is done to prevent back reflections. The driver is phase and time aligned. According to Ohm's literature this results in a single arival from each speaker. From my experience this is true and results in excellent imaging. You can hear both channels even when you are not in the listening room. The nominal impedance is 6 ohms. The drivers are round cans and are installed in a vented column enclosure. There is a single set of contacts on the bottom of the column and the crossover is internal to the can so it is not biampable. Placement is very simple. You need to set further back than the distance between the speakers. If you use them for surround sound then will want to go with a processor and separate amps as you want a least 250 watts to run them.
Overall I like the speakers a lot. My only complaint is that it takes a lot of power to make them play loud. There are other speakers that are more efficient with better dynamic range. I doubt that anything else will provide better imaging though. Hope this helps. |
I am facinated with the prospect of hearing these speakers.
Years ago I heard them at dealer, but only briefly. The next time I went back, they were gone. I assumed they went out of business. Is it fully omni-directional. Are they time and phase coherent? They seem to need power, what is the impedance range? Has any one seriously measured them? Is it truly a single driver speaker system. If not, do they use cross-overs? What kind? To what other drivers. If so, are they bi/tri ampable? What type of box do they use (sealed,vented,transmission,other)? What is the suggested room placement/requirements? How far does the listener need to sit from them. Has anybody used them with digital room correction/cross-overs? How about surround sound? Sorry for all the questions, but the web site is not that informative. From what little I know they seem to offer so much promise, especialy if all the new digital options fufill thier promise. Sean, please share your impressions of the Huff stuff. As always, thanks in advance. |
Sean,
I never opened the sealed can so I can't comment as to what is inside. Whatever it is it works great in my opinion.
Best regards,
7p62mm |
Years ago one of the first speakers to wow me was a pair of Ohm's.
I have been experimenting with a second "budget" system an recently decided to try the new Walsh Sat's that they advertise on their site. In my mind it solved some of the problems they used to have with loose bloated bass as they filter out 80hz and below.(You must use them with a sub.) That also allowed me to use a tube amp as before you needed an amp with high damping.
I have had the Walsh Sat's for a week and the sound is incredible!!! I have owned or auditioned many speakers over the years, most at considerably more money, and in some regards it beats them all. Took me quite a while to position it correctly and had to use some room treatments but has been well worth it. Sound just seems so more real than other speakers. Before this the only thing that came close was Magnepans. I am having a couple of my musician friends over in the near future to give them a listen. If anybody is interested I will post a review with their comments. For my ears there dosent seem to be any better for the money.
Good listening,
Bin |
I to have a pair of 300 mk11, also found they need a lot of power to sing. Having owned both f"s and walsh 4"s these are to my ears more refined. The cabinet although is not as well done from a veneer standpoint as the 4"s were. I have been able to compair these to original walsh 5"s and find the 300 more detailed with better imagery. Nathan you should trial a pair of walsh 5's with your experence it would be interesting to hear what you think! |
Out of curiosity, what did you find inside of the "sealed can" in yours ? Please be as descriptive as possible. Sean
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I own a pair of Walsh 300's which I bought in 1999. Overall, I am very happy with them. Advantages: 1)excellent midrange and great sound stage. Don't have to sit in the sweet spot for good results. 2)Decent bass response. 3) Reasonable price range. 4) Easy to set up. Don't have to spend a lot of time to get them positioned for good sound. Disadvantages: 1)not very efficient. They take a lot of power to play at loud levels. I currently drive mine with a Bryston 4B (250 watts @ 8 ohms). 350 watts would be better. 2) At high levels the bass seems to distort somewhat. I plan to fix this by adding a Velodyne subwoofer someday. 3)Fit and finish is not that great. I am disappointed here. 4)Internal wiring and interconnect quality is somewhat low. I plan to re-wire the speakers someday. There is room for improvement here; but, I doubt that it would make much diffence in the sound quality. Overall, I am very happy. My friends like them too. I don't agree with the gentlemen who says that looking at the guts of the driver soured him on the sound. It amazes me that you get so much high quality sound out of relatively small driver. Another plus is that if one fails out of warranty then they only cost around a grand to replace. Note: I have not had to do this up to now. That's my take on them. |
Thanks for all the responses here and those sent to me via e-mail! |
Talk about coincidences !?!?!?! Huff is the manufacturer that i was talking about. As luck would have it, he will be demo'ing his products at the next Chicago Audio Society meeting. Boy, i can't wait for this : ) Sean
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http://www.huffloudspeaker.com/ |
There is another Canadian based company that takes the "improved" Walsh ( aka "Dick's Dipole Driver" or "bending wave transducer" ) that GP makes and modifies it. It is supposed to blow smoke and walk on water. That is, if you're into the type of presentation that a 360* driver delivers. Can't remember their name, but i want to say it was of Irish descent. If i remember correctly, the price on them was about $18K - $20K for a pair.
John, are these being shipped to you ? If so, drop me an email. I can give you some hints on how to save the drivers. They are EXTREMELY fragile at this point in their life and will need to be "TLC'd" all the way. Sean
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they use an improved version of the original walsh driver. quite expensive, tho...
doug s. |
Sean , will do on the A's, though I am pretty sure the gentleman will have to die or become ill 1st for me to get them, and I like him too much to have that happen anytime soon. I kinda have a standng offer with him, and I think if he were to sell them, I think it would be to me. He liked the fact I knew what they were the 1st time I walked in the room, etc. Hell, I was impressed myself, was a very good guess on my part. He is a wealth of information, and can walk into hs closet and pull out stuff I have never seen, a Houdini of audio so to speak, like so many of the oldtimers with a love of audio are and were.
Will do on the F's as well, should have them next week, one of my many trades. I am actually a little afraid to see the condition, but if they are working, I can work with them. |
John, if those A's ever become available, PLEASE let me know. I will drive to pick them up. As to the F's, drop me a line if you pick them up and we can compare notes. I have two different sets of modified F's that i dearly love and will never part with. There were more than a few variations during their production run, so one set can vary from another. How big of a difference there is between them would depend on how far apart they were in production.
Noel, the original owners of Ohm had sold it to the current owner, John Strobeen. While i guess that he is very good to work with and takes care of his customers, i think that the newer products are WAY different than the "old school" models that you remember them by. If you ever saw that insides of one of their "Walsh series" of speakers, you would be HIGHLY afraid to spend the money on them. Jon Risch described them as being "built and designed by a child on drugs". While they do offer a completely unmatched ( at least in the speaker industry ) amount of time as a trial period, I know too much about their internals to take them seriously. Let's just say that their newer "Walsh's" are not "Walsh's" as you or i would think of them. That is why they say "no user serviceable parts" within their "sealed cans". They don't want you to know what is in there. If you did, not only would you feel sick, the mystique would be gone. Sean
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I just had a pair of E's that I had traded for. I have to say I thought it was a good value for the money. Bass response was decent, imaging, detail, highs all that good. Wasn't great, but it was and is a $600 speaker. I found them to be impressive for the money. I am about to get a pair of F's that i wll play with for a while before I do something with, just so I know. There is also a pair of A's owned by a local that I have listened to for quite a while and considering the age, I am damned impressed with them, especially the low end response. |
