Ohm Walsh F Hope of Resurrection

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.