Now I have F's with rotten surrounds, but rest look nice, perfect even. Cones, spiders look great.
One surround is done, decimated. Other is intact, perhaps replacement as is not identical.
Perhaps I try replacing surround? Any new and improved surround options? Willing to replace/ get repaired more, if necessary.
Cursory search doesn't reveal any drop in replacement. Or, am I wrong? I see the Ohm return/upgrade to newer version options.
Experienced and insider opinions sought. I'm not cheap, and I'll spend the money to obtain the exceptional if needed. So, what are the likely and less likely options TIA What is that one "clone", HHR? Need to check... i heard it at a show years ago.
This is not an equivalent to the new, HHR Exotic version TLS-1. I was told directly by Dale that there are dozens, literally, of changes to the new design. So, don't think you would get the new one for half price; you won't. There are aspects of the refurb that are not on the level of the HHR Exotic version.
Still, were I in the market for a speaker change, I might do it. I was also considering a review of the new version, but he said he cannot afford to build for review; he only builds for orders. I understand that when it's a small shop and custom product. So, there's no review coming; sorry. I think it would make for a compelling article, something quite different, but not all review ideas work out between the needs of the manufacturer and the reviewer. This is one of the difficulties of smaller businesses with exquisite products.
I think the upgrade to the F is a great option, so sure, talk to Dale!
I don’t know how Dale works but maybe the drivers can be done and sent and then user installs them to avoid shipping large heavy cabs. I know in many cases Ohm is able to do repairs and upgrades that way.
My F5s came in 3 cartons per speaker. One for the refurbed F cabinets, one for the driver, and one for the grille cover.
Connection was a snap and drivers attached to cabs with wing nuts.
You’re getting into details that are best pivoted toward Dale. :)
Time to head downstairs and continue work with another amazing speaker - something you guys probably have not encountered prior. :) You'll have to watch for the review, not immediate.
The speakers are at a repair facility; not discussing particulars at this time.
The tech finds some black goo that is like a tar, that has gummed up the driver to the point it was frozen in the coil. He said he has never seen anything like it with these speakers. I sure had not seen anything like it. It seems so improbably wrong that it makes me wonder if it could have been sabotage (especially since inside the speaker there sat a smaller (wrong sized) spider that had soaked up some sort of oil substance), or perhaps someone so inept that they can't deduce that the part had to move freely or it would seriously compromise the sound. Seriously, who puts black, sticky, gooey crap in the gap? Did some kind of lubricant at one time age so badly that it froze the coil unit it was worked loose again? It seems counter-intuitive to proper treatment of a driver.
Could it be that there was rubbing of the voice coil after a repair - there is evidence it likely was repaired - and someone sought to cover it up by using a lubricant? Perhaps; I wouldn't put it past some people. That may make sense, given how hard it is to redo these cones. Perhaps someone screwed up, and tried to cover it up, caring less about the longevity of the speaker than not being discovered. Perhaps I have solved my own mystery...
It's also not as if this would normally fall into the driver, as they are typically inverted, with the coil and magnet structure higher than the spider and cone.
Has anyone ever encountered such a thing? I am willing to be educated on all this if there is a reason for such things to be done.
The fabulous news... it has been removed, and it appears the drivers are well on their way to restoration! I was VERY wise to solicit the help of experienced persons on this. :)
So, one possibility is that it is ferrofluid? This is a very experienced tech, and I think that he would have known that possibility and would have recognized it.
It seems some grease may have been used on these old drivers, perhaps for heat dissipation? It sure does not seem intuitive, especially since the one does not seem to have it.
Looking at the images and discussion of ferrofluid, it appears that may be the substance. Does it get gooey and hard enough with time to lock a driver?
Spider removal: Voice Coil Centering With Ferrofluid
The presence of ferrofluid exerts a uniform radial centering force upon the voice coil in the air gap. The magnitude of this force is dependent upon the strength of the permanent magnetic field and saturation magnetization of the ferrofluid. The greater these values, the stronger the centering force. Reduced scrap rates on the production line, reduced field returns and reduced distortion (due to the suppression of radial and rocking modes of the voice coil) are some of the well-known benefits of this centering force.
In recent years, the availability of high saturation magnetization ferrofluids have allowed designers to completely remove the spider, relying on the ferrofluid to center the voice coil in the air gap. This technique not only yields lower cost and a simplified production process; it also removes the well-documented nonlinearities present in all spiders, resulting in lower distortion. In general terms, the saturation magnetization values of ferrofluids used in spiderless designs should not be lower than 33 mT.
I now if the tech used ferrofluid to center the voice coil because of the difficulty of doing so with the Model F driver. Then, because the wrong fluid was used, it got gooey and froze. So, perhaps the incompetence theory is most accurate.
I feel like I've read in the past that the original Ohm F's were essentially sent from the factory "broken", that they leaked because of some design flaw and that what you're experiencing is actually normal for these speakers. I'm certain a search on this subject will uncover this problem, perhaps Dale at HHR would know of this.
I do not have answers as to whether the goo was ferrofluid, but that is likely the best explanation. So, perhaps we'll see if when I use them it takes 300wpc to get them to wake up, and 301 wpc to blow them up!
Well, good luck! Nothing to lose and who knows maybe they can still deliver something that is hard to find otherwise.
I can tell you that the Walsh CLS design can take pretty much anything you throw at it with very little compression or risk of damage, so John Strohbeen definitely knows what he is doing there. Lessons learned over the years it seems from that article, starting with attempts to salvage original Ohm Fs.
I’ve been running various models hard for almost 40 years now, never a problem. Seems like the mastered application of ferrofluid is a factor for that.
IT’s still always best to avoid clipping at all costs... reserve power and the ability to handle it is your insurance policy for that with most good quality speakers in good working order.
In the interest of getting the most possible out of my Ohm Walsh F5s, I’ve been running them with 500 w/ch (into 8ohm doubling to 1000 into 4) BEl Canto monoblocks for a number of years now with outstanding results. I bought them planning to throw the kitchen sink at the biggest Ohms in order to max out what they can do. Those amps can drive almost anything to their max and also work well with other smaller speakers I own or have owned with them like my smaller Ohm 2s, kef ls50s, Dynaudio Contour monitors and others, but the Ohms are champs at going loud and clear off however much power you want to throw at them. Meanwhile they do as well as most with lower power amps, but its when you throw the kitchen sink at them that they truly distinguish themselves from the competition and shine. Similar to mbl and GP in that regard as well from what I read.
mapman, some nice guidance, and yes, I plan on adequate clean power. I have no desire to abuse gear; all my years I have never blown out a driver, even when I built my own "cabinets" for my coaxial car speakers that sat in the hatchback area aeons ago. I'm more into quality with quantity as opposed to quantity and more quantity.
I never take speakers to the point of clipping; I greatly value my hearing and do not wish to introduce the potential for hearing damage. So, these will be handled well, not abusively.
I will look forward to trying the Pass Labs XA200.8 Monos with them. I suspect they will be quite attractive sounding with those amps.
Yep agree, can’t sacrifice quality, but when it comes to symphony orchestras, big bands, and the like, it takes more than average muscle as well to deliver the goods at home in a manner that at least somewhat resembles what one would hear live. Especially with modest sized full range speakers. Just have to be sure to take care of the ears along the way as well. Too much too often is not a good thing no matter how exhilarating it might be otherwise..
Douglas, You could talk to Dave Cox of Puckerbrush Audio in Norway Maine. Dave is a Ohm speaker collector and has worked on a number of Ohm f's over the years. He is a friend and has worked on such speakers as a couple of JBL Paragons for me with great results. I had a pair of F's a number of years back and they definitely have a certain magic to them. I must say that I heard Dale's speakers at Axpona and they were out of this world! Best of luck, Bob
Thank you all for the continued advice and encouragement!
I have acted on one avenue of potential repair/restoration, which I found myself. My request from a local dealer went nowhere, and the request of a well regarded speaker repair shop about 1.5 hours away sank when they refused to work on it. That convinced me not to try by myself; good move, given I have zero experience in this activity.
My repair plan for the speakers involves two 12 hour round trip days in the car, as I was not interested in shipping them due to the potential for damage. I am willing to work a bit to get these drivers back into operating condition. The drivers have been in the possession of the repair facility, so they should be done sooner rather than later. Then, one more day in a car, and... COOL OMNI SPEAKERS TO ENJOY! ;)
In terms of the cabinet damage, where it is splitting along one of the front corners, at least a clean split from the outside; I will probably just shoot some glue into the fissure from the inside of the cabinet to prevent further compromise, probably use Gorilla Glue, and then put some wood putty into the gap. If I sand it down right, it shouldn’t be ghastly.
CALLING CABINET MAKERS/REPAIRERS... What do you think about that fix? The MDF seems to be the patchier kind, so trying to push hard on it and screw it back together might cause more damage. What’s the best stuff to shoot into the gap to hold it?
Lastly, I think I’ll try a simple, likely effective maneuver of placing about .5" pliable foam sheeting inside the cabinets (not glued, just put in position) to help with cabinet resonances. I suspect that will tighten it up a bit on the low end. Rapping on the cabinet is like ringing a wooden bell, even while the stock stuffing is inside! I’m not going to have that kind of distortion if I can help it. If my solution doesn’t work, I have not lost much and I pull it out. Or, maybe I can put steel straps inside, and fill the cabinets with 400 pounds of sand! ;) LOL I have filled one or two speaker cabinets in the past, and frankly, I didn’t like the result all that much. The bass on this will be like Harbeth, Audio Note, Tannoy, etc. with the hollow cabinet feel, which I’m not overly crazy about, but it’s an alternative toy. I don’t need to perfect it.
Imagine, these were a "last resort" call from the family who knew I was big into audio, as they were about to take them to the dump!
Hello Doug. Remember when we sat listening to the TL-1 in Dale Harder's room at Axpona? IMHO that was best in show. After that I wouldn't bother with Ohm F, but to each his own and a good project is always interesting. Talk to Cascade Audio Engineering about coatings and appliques to damp MDF enclosures. I have used their VBLOK paint to good effect inside various MDF cabinets. You can mix that with brass powder if you want to get fancy. They have since introduced a variety of padding conceived for automotive applications that may help as well. Use two-part epoxy mixed with saw dust to repair or strengthen broken or crumbling MDF.
Repair now underway. It seems one driver is original and the other not. The original does not have ferrofluid, as it had not been invented at the time. A different lubricant, such as a grease, was used. At some point one driver failed and was replaced, the new unit utilizing ferrofluid.
The drivers are having spiders and surrounds rebuilt, the one with hardened/tacky ferrofluid has been cleaned, and both will be reconditioned with new ferrofluid. My understanding was that the original units were prone to failure, but the addition of ferrofluid ameliorated that problem.
I may have reconditioned Ohm Walsh Model F’s for Christmas! That would be fun! :)
22 hours of driving, 1,370 miles, and total for project, including travel costs, of $400. DONE!
Speakers are warming up (slightly; they were in car cabin, of course), and will be assembled tonight. Perhaps a first run this evening, too. We'll see. The hard work is over, now it's RELAX TIME! :)
Now for the vintage Ohm community, a question; I have heard the joke re: 200/300 wpc wakes them up, and 301wpc blows them up. Ok. I have a super-clean class D that puts out 600wpc into 8 ohms and 1KWatt into 4 Ohms. Is this inherently a problem for these speakers, or only� relatively a problem, i.e. temptation to play them too aggressively? I see mapman is using plenty of clean power.
I wonder if it was coincidence; my pair of Ohm Walsh Model F were the only ones at the repair facility when I dropped them off. Today, when I picked them up, mine was one of four pair! They had never seen such a thing with that speaker. Perhaps our enjoyable brainstorming is motivating some owners? Or, just a freakish occurrence, which is certainly not beyond probability bounds.
Douglas John Strohbeen has stated in interviews the issues with driving Fs well without damage and maintaining them properly is supposedly the reason why the design was dropped. Not practically supportable. I think with any amp you just want to be very careful. It’s the CLS design driver that replaced the original Walsh driver that resolved that issue. Every CLS Ohm I have owned will take whatever you throw at them and deliver effortlessly. I have never heard or owned original Fs. Mine are newer CLS design on refurbed F cabinets. Totally different. So I can only repeat what I have read there. Ferrofluid was introduced into the F design as I understand it to help address that issue as well. Clipping is never good either hence the challenge. I would try a higher power amp like a Class D for more bang for the buck if needed . But be careful.
Been quietly following this thread, and glad that you got the F's fixed.
There's been a lot of talk about the hair-trigger watt limit to blow up the F speakers. As long as you don't tempt fate, it should be fine. I've run my pair of F's for may years with a 300 W/ch (into 4 ohms) power amp, and really never needed to put more than a few watts to get loud enough in the room.
Let us know how the speakers sound when you get them fully set-up. Congratulations, again.
pch300, the sound is well, vintage. It lacks a lot of top end sparkle that I have come to expect from superior speakers. But, that is reasonable, given the age and design. They simply never were able to create the shine that is with newer technology. The big call to fame was the mushroom cloud soundstage, and they have that. Am I going to add some super tweeters to open up the top end. No, I’m not putting any more money into them, as there are fundamental limitations that are obvious.
They will be curiosities, something to put in the system when I am bored or want to hear the omni sound pattern. It’s a good thing I have a radically clean rig, or else I couldn’t take them at all, as they would be horridly mushy.
I was fairly realistic in my assessment of what to expect from the repair. I didn’t expect the world, and they have not given it to me. For a few hundred dollars they work fine. I haven’t pushed them yet, but I will at some point. If they die, they die. I’m not going to keep them as a souvenir that is not worth opening up and running. They have physical defects, i.e. the cabinet compromise and some ferrofluid stains on one upper paper driver, so they’re not worth much.
This does confirm once again that most vintage equipment is beneath my expectations nowadays. I have yet to work with any vintage equipment that I could stand in the primary rig for more than a day or two. The sound is simply far too compromised. The price is right, for sure! But I don’t have to settle for bargain speakers. So, why did I in this case? Again, because they were presented to me as a speaker charity case that I knew I could revamp on the cheap. I don’t need another reference speaker, and this will definitely never be close to that. I just wanted a fun project. We’ll see if over time they "blow up" in a good way, or in a bad way. But, I’m not going to keep them forever if they never have the capacity to thrill. Having a unique soundstage simply is not enough to entice me to love them forever. I slowly upped the level and it didn’t seem to phase them. But, I got bored and put the Kingsound King III ESL speakers back into the mix. Much more excitement and prodigious. Who knows, maybe they can take a lot more; I was very light with them.
So, what do I expect for a couple hundred bucks? About what I got. Good enough for now. Next run I’ll push them harder to see if they have more to give, because I handled them with kid gloves this time, and they didn’t really shine in terms of the orb soundstage they can do. They’re either going to bring satisfaction, or be destroyed. I will not harbor low cost speakers that long term do not bring fun. Well, "destroyed" is a bit too harsh; they simply would sit around and perhaps be sold cheap to recover the costs or given away. But, please, people, do not contact with offers to take them off my hands. They're for fun and I don't know how long I'll be entertained. It's not your free speaker project. :)
I will put the Kingsound King Tower omni speakers back into the rig soon. I want to gain a clearer picture of the fundamental differences between that omni and the old F. I was going to sell the King Tower omni, but maybe not quite yet.
I was going to redo the batting in the bottom of the cabinet, but I wonder if the drivers would react differently, potentially have too much excursion if the fairly solid batting was not kept in place. It would be stupid to remove the pretty solid mass that acts as an air brake, then push the drivers such that they had too much excursion. I think I’ll let that one go.
Nostalgia can be a strong force in the decision making process of the audiophile, but in my experience over decades, in every instance where I put money/effort into a vintage product, it did not yield acceptable performance. After a dozen experiences or more, at what point does the system builder conclude it is a less productive activity, at least in respect to pursuit of extreme sound? I am pretty sure that were I to put the $7-8K into a more extensive rebuild of these, and procured new cabinets, I would still end up at the same conclusion; nice, but not overwhelming.
After a while, when you have heard hundreds upon hundreds of speaker systems, many in your own home, you are able to globally assess the technology's capabilities. There are fundamental, hard limits on each tech, and with a realistic assessment of the limits, decisions can be made in regard to whether a certain investment into upgrade will be worth it. Most often, I rather enjoy diversification into a different genre, than an attempt to idealize one genre of speaker. Experiences available through a variety of speakers is unparalleled, imo, with focus on one genre. So, my motivation to try to turn the Ohm Model F into "the One," is not strong. I have chased the mirage of the One many years in the past, and it always ended up disappointing, primarily due to allocation of resources into a narrower range of performance. I'm not willing to push on that button again. I have learned to know myself enough as a system builder to avoid what are for me less productive changes.
However, there is another omni speaker sitting here... I may today put the Kingsound King Tower omni speakers into the rig to see informally how they compare with the Ohm Model 7.
The story regarding the King Tower is interesting, and as a reviewer with curiosity I was in the right place at the right time. Over the years I spent plenty of my own money attending shows across the country. I was not paid to go as a reporter, so this was extra expenditure for unpaid work! How stupid, right? Except that I knew there was no other way to gain extensive experience with gear except by getting exposure to it. I knew I could pick some winners for my ownership if I could hear them. It was that willingness to spend money that most would consider a waste that led to some very cool outcomes, including the King Tower. If one does not have the vision to invest into potentialities, then the future is more limited.
It was at one of the RMAF shows that I first saw them. I believe they were shown two years at the show, and they were shunted off to the side in a little system with mbl mono amps. They looked stupid, with bright blue foam balls in-between the bass and midrange modules. No wonder they didn't get attention, as they looked ridiculous. But, as I surveyed the larger design, I thought, "Ignore the stupid blue foam balls..." The design had potential, I thought, so I asked Roger DuNair, the importer at the time, to fire them up for me. He did, and I thought, "Wow! This really has potential!" I also thought that it could prove to be a SERIOUS contender to lower end Maggies.
I bugged Roger for about two years to review them, but eventually he called and said he was not going to distribute that model in N. America. Did I want the demo pair? YOU BET! SEND THEM! The miracle of the story is that while I have had three other smallish tower speakers destroyed by the likes of UPS, FedEX and DHL over the years, these arrived intact! AUDIOPHILE MIRACLE! So, even though they are not my primary speakers, they have a nice set of memories associated with them. I believe they may be the only pair in North America.
The first thing I did was apply myself to removal of the stupid foam balls! Thankfully, they were easy enough to remove and as the cabinets' downward wave guides were anodized, I was able to successfully remove the adhesive with zero cosmetic blemishes! YESSSSSS! Now, they look respectable, and sound better. I consider the existence of the blue foam balls to be a reason that they were never sold at the show. It can pay to have a bit of proactive imagination in regard to a product! :)
The King Tower I already know will have scads more resolution, with its larger omni ribbon tweeter and super tweeter atop. It also suffers from cabinet coloration, as does the Ohm Walsh Model F. No getting around that, but I had thought of perhaps opening up the cabinets on the King Tower and treating them to dampen some of the resonance. I may still do that.
I am looking forward to hearing the completely kick ass new amp under review with the King Tower. The best part is that the King Tower, unlike the Model F, can be bi-wired. That means I can use two more channels of 600wpc of super-pure power on the King Tower. Frankly, it would expect it to outshine the Model F significantly in some respects, and I would be quite disappointed if it didn't.
I'll say this; if it were a choice between getting this new amp under review or upgrading the speakers, it wouldn't be a difficult decision - THE AMP, no question about it. I wouldn't dream of opting for upgrading the old speakers and missing out on this amp. The amp is revolutionizing all the speakers I use. That is far more important to me than upgrading one speaker.
pch300, you sound like you really want to do the upgrade. If you have the means, why not? This thread may be the catalyst for you to realize a dream. If so, great! I get it when it comes to adoration of a certain genre of speaker; I lived that for a long time. So, if it's a dream of yours, then go for it! :)
+1 @trudat IOW it’s the HHR Exotic that proves the merit of Walsh’s conception-- or maybe a
German Physiks. A $400 restoration of a Ohm F is a straw man.
I find it refreshing return to my earlier days, when I defended inexpensive audio. How many times have I been accused of "selling", as though my primary goal is not performance, but convincing others to spend money. Let this exhibit stand as an example of the blowback that happens when fans of a certain brand or speaker chide someone who could, but choses to take the economical route!
This makes me a hero for the budget audiophile! ;)
So far, the best aspect of this project has been getting the King Towers back into the rig. Man, am I happy to have them! It's great to have direct comparison to a full range driver omni. It will be fun to switch between in order to gain appreciation of each technology.
I'm going to put the Model F back in and jack em up. They're no good to me treating them like paper mache. If they break, they break. I've already gotten a valuable, yes worth the money and time, comparison between speakers. Consider this exploration for the sake of humanity, like Space-X, only on slightly smaller scale. ;)
For those appalled at this decision, I remind that this was a set with major damage and on the way to the dump. I would never ever treat review or more valuable gear in such fashion. Feel free to check with any manufacturer whom I have reviewed, or my sales of my gear.
I'm pushing the issue, building systems at advanced pace to get to the end of the matter. In a day or two I will know whether the F is worthy of more time. It could perk up. I'll build yet another rig for more perspective.
Once again, as consistent in this stream of consciousness discussion, not a review, I make no claims or promote no expectations of either HHR or current Ohm products.
Doug, as a check point to your repairs you might speak with Harry Weisfeld. He has a pair of restored stacked Ohm F at the VPI house. I haven't heard them, but perhaps he has some ideas to help bring out the best in the F.
My recollection from back in the day is that OHM-Fs did not have shimmering highs, nor could really loud sound levels be played without some loss of control. What they offered was room filling sound and a good soundstage at moderate volumes. IIRC my memory from this long ago is suspect.
@douglas_schroeder , I'd be interested in listening to the Kings Audio King Tower. They look super cool. I'm also glad that the majority of posts have been spot on and helpful. Bob
Thank you gentlemen, for your thoughts! All input is appreciated!
Today I tried to blow them up! Not really, but I did as mentioned and laid a lot more amp output on them. I stared with an alternative class A/B integrated (Kinki Studio EX-M1+ with sundry discrete opamps inserted), and pushed the speakers to pretty high levels, perhaps 85dB. NO problem! They seemed not to stress, which is ideal.
But, the resolution, as russ69, recalls well in his comments, is nothing to write home about. I returned to the aforementioned "magic" amp, and yessir, this is certainly a magic amp! Wow, what a class D! Combo with the Exogal Comet DAC is pushing the speakers even better and with more resolution. Now the resolution is listenable, but nowhere near exemplary.
Yes, the single driver firing into a box is not exemplary resolution. The mid and upper treble is more pleasing when they are driven harder and the convergence of the omni fields is in more effect. At low levels, not nearly as inspiring, as might be expected. The "sublime" comment initially was at quite a lower level, but now I will not hesitate to play them harder.
For comparison, both the King Tower and Ohm Model F restore were placed in identical position, and here are some results; there is a sizable resolution gap between the capabilities of the King Tower, and the Model F, across the frequency spectrum, with the King Tower dominant in that respect. The soundstage is not as coherently "mushroom cloud" with the King Tower and is taller, as also would be expected. The fullness of the soundstage and encroachment (or perhaps "intimacy" and "immediacy") upon the listener is superior with the Ohm Model F. It seems to shift the soundstage forward toward me about four feet, such that the umbra is about three feet ahead of me, versus the umbra of the King Tower being about 7 feet ahead of me.
That is the calling card for the Model F and this rebuild. One has to excuse a fair bit of flabbiness and indistinctness, but the mushroom cloud is distinct with full range omni, and that helps to offset some of the disappointment in indistinctness and resolution. There is a curious tie in with other full range speakers, and the Tannoy Glenair comes to mind (reviewed). I can mentally image the Glenair's driver pointed downward similar to the Ohm, and capture the affect of it driving into a pile of foam. I really do wonder whether I should remove some of the foam. I suspect the speaker would wake up quite a bit. After all, it didn't strain when I put it to higher levels, so what's the harm? I am very curious how the driver's nature would change, as well as the cabinet coloration. The cabinet is really dead now, and I suspect the speaker would benefit greatly from a bit of "Harbeth treatment", i.e. hollowing out the box somewhat. Maybe I'll try that next.
None of this should be surprising, but overall I am very happy that they are tolerating higher levels of massive power, the best outcome that I believe possible for a vintage set. What will be particularly helpful to me ongoing is having another soundstage to work with. I now will have full range omni, quasi-omni, quasi-line array, and big ESL, as well as open baffle horn hybrid. There is another speaker making a splash, with its own unique soundstage, but that is a different story for another time, a review actually.
Overall it's been worth it, and I pleased that the are not falling apart with some pushing. That makes them worth keeping and using occasionally.
What do you guys think about the idea of removing perhaps 1/3 of the dense foam pieces in the cabinet? I think it may be a winning idea. I don't know that the removal would adversely affect the driver much, as it's a pretty sizable cavity and with some open space between the driver and foam. What say ye? This is basically an ongoing experiment, play time, so I may as well do it. I was willing to take a risk that they speakers would fail, so why not do foam remediation? I am wondering whether this would aid the resolution, and at this point I think it likely would. Only one way to know! :)
Thought experiment; Imagine taking a megaphone in order to shout out clearly over longer distance. But, as a requisite condition, you must hold a dense pillow 1" from the mouth of the megaphone! You see, the rules are such that the gap between the pillow and the megaphone must be maintained.
THAT, my friends is the equivalent illustration to the design choices used in the old Model F! I did the foam removal, and I'm not going to talk about the potential for asbestos. As I say with other sensitive maneuvers, IT IS A DO AT YOUR OWN RISK ACTIVITY. So, let no one say I told them to remove the foam inside the Model F, not without pointing out their responsibility to acknowledge potential issues. I am presuming the old foam would likely have properties that might militate against safety today.
Now, on to the great news! IMO, this speaker has been resurrected! I'm WAY more excited about it now that when I said it was sublime. The removal of half the foam has allowed the driver to work as it should! The indistinctness, lack of high end sparkle, muted, weak bass was all really getting to me! For a design that was supposed to be all that it was not doing it.
It had to be at least in part due to the foam. You don't take an open moving driver and stuff thick material 2" away from it, and not expect the driver to choke! This speaker is a study in the convergence in the '70's of a brilliant, innovative driver, and at the same time awful construction methods that absolutely killed a LOT of the speaker's potential. It's hilarious that such a loser move with foam reduced this wonderful driver to a pathetic performance.
Well, NOT ANY LONGER! Now, the driver is acting as I would expect, a MUCH closer approximation - as would be expected - to the HHR Exotic model that I have heard. That was a big part of the frustration with continued listening; it just was not great. It was big soundstage, and that was about all worth praising. Now, the speaker has indeed come alive! Now, the driver sounds as it should, with respectable sparkle as well as spaciousness. The top to bottom frequency balance is commendable, though not SOTA. The soundstage is FULL now, not anemic and struggling to expand. The dynamics are SO much improved. The driver does not sound squelched, but has pop, and the bass is a big bonus, as the cabinet half full has a great, solid and powerful bass response!
There are so many insights from this to be gained, including not to hold an older/vintage speaker as sacrosanct, such that it would not be improved from futzing with it. Another lesson is that a designer might be brilliant, but the conventional aspects of speaker making of the day can reduce what would be an even more brilliant design. Yes, of course, the standards have changed; that's part of the reason I was not accepting the performance. Free air motion of the driver is SO important, and without the back force of the foam blocking the driver's operation, this IS A RESURRECTED SPEAKER!
Now, it's not a charity case, but an authentically reasonable selection for listening to as a quality transducer. These speakers probably within a fairly short period of time would have been on the way out - somewhere. Now, they will stay, because this one change has brought a cascade of positive changes, and the driver is operating closer to my expectations.
With this final fix, the restoration is a big success! Now, beyond a shadow of doubt, this IS the best $400 speaker I have ever owned! It now may take its place longer term alongside my other speakers, and because it has been resurrected to play with above respectable levels of sound quality, it will be used in rotation.
Have I overstated my conclusions? No, I have not. This was a roller coaster of changes, thankfully most of them leading to a more favorable result. Had I been too timid to rip into the foam, treating it as though it was sacred material, this never would have resulted in my finding deeper pleasure in them. But, as it is, speakers that are not mostly cutting it need to be reassessed, and I do not care whether it is iconic or not. NOW it performs along the lines of what I expect a great omni to perform.
Conclusion? YEEESSSSSSS! I now have a vintage speaker restored to a quite respectable sound quality level, and I am most gratified that I futzed around with it to make it happen!
Now, to give some balance, are these suddenly replacing my other reference speakers? Of course not, but neither will they languish as an also ran, nice idea project that failed. That's where they were heading before I motivated to try the foam removal. They will be a pleasant alternative, and a respectable one, to build systems for enjoyment, and even for reviewing. The change has been good enough, I feel, that they can be used occasionally for reviewing. Prior, I wouldn't have dreamed to do so.
WOW, what a difference removing the pillow makes!!! Again, those with older model F's are not being told what to do, and consider your bravery if you want to alter this iconic speaker. But, performance is SO important to me that this was THE solution to the speaker's foibles.
Now, I think I am done. The restoration is acceptable to me, the performance as good as I was hoping. It has solidly moved along the spectrum from "sublime" quite a bit closer to sensational. No, not drop jaw on floor, but much closer. I now consider it a brilliant move on my part to seek the affordable fix, and to trust my instincts in regard to pushing the speaker further along. I am SO happy I did not accept the weaknesses, but made better things happen. BTW, note that this all happened without burn in. I am an advocate of change to systems, a system builder, and that is a fundamental reason why I ended up with a positive outcome. Waiting would have done nothing to address the fundamental issues, and being active has gotten me a very nice vintage speaker redone performance-wise within a couple weeks of return from repair. BIG, BIG WIN! This has been the singular best turn with a vintage product I have had, but then again, I was more aggressive about altering it than I have with other vintage gear. Nice lesson learned, with all upside. :)
Given the difference in dispersion patterns between those two as I understand it, I would wonder if the same location can serve both best. The Fs are full omni so probably will benefit from more distance from all walls I would expect. Never heard Fs but have heard mbl and GP. Mbl in particular only sounded uniquely and mind blowingly 3 dimensional in a very dealer custom showroom with lots of distance to walls, especially rear wall, non parallel side walls to the rear, and treatments (old United Audio showroom in Annapolis Junction MD) Same setup at shows: way more meh. Also I seem to recall Fs even new only spec’ed to 16 kHz whereas most speakers in their day were spec’ed to 20 kHz. Most people raved about the imaging but not about the high end extension. Separate super tweeters would be an interesting add I would think.
mapman, yes, I concur; this has been rapid testing, and comparison of same location for a quick read on the performance of the Ohm and the King Tower soundstage. The positioning had nothing to fix the inherent problems I discovered and addressed. I would presume that somewhat different location of these omni speakers might be optimal over time.
The speaker now "breathes" as I imagined it could. The upper end of the spectrum is transformed. I had been thinking, "Well this stinks; these would need super-tweeters to save them," but the fact is, they wouldn't, not with the speaker in that condition. It wouldn't tighten up the bass, or truly balance the frequency spectrum. I wouldn't add anything to the resolution problem cased by the overstuffed cabinet.
The additional treble now is sufficient that they sound pretty well balanced. I would say they lean to the soft side of treble, but nowhere near the faint treble they had before moving half the foam down to the cross member of the cabinet. The driver was literally being suffocated by operating with a constrained air space. It literally had nowhere to push the air! One can imagine how that would dampen the materials of the cone! How can one get a natural ring to treble when back force is pushing on such light material? It's stunning to think that the design gave so little consideration to it, considering how basic and immutable the laws governing it. But it's easy to be an armchair critic of the past when assessing with half a century of tech development in culture. I am guessing it was seen as a brilliant move, along with the driver design.
Soundstage has such a pervasive influence upon the listener. When approaching a new speaker, I try to actively assess, then lessen attention to the character of the soundstage, as fixating on it can cause someone to overlook issues with performance. I am happy that I used my experience to pick apart the performance, because it has led to this speaker being upgraded quite nicely.
Music is a 3-d experience to various degrees live. When a 3-d soundstage is maximized as I have heard uniquely possible with omnis, it is possible to discern a lot of detail that may be lost in the congestion otherwise.
Different forms of detail with different genres. Omni wins in terms of scale, atomization of images, which can seem to be more info. It loses when it comes to image density and localization, which is a loss of info.
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