Fixed (Easy!) a Major Design Flaw of the Ohm Walsh Model F

Still the characteristic muffled mid/bass which will not be eliminated.

Have you tried experimenting with the batting inside the cabinet?

The density and the thickness of the batting does effect the SQ of the mid/bass specifically.

Certainly true for my Walsh 4's

uncleang, yup, I did so. On my other thread here to the effect of resurrecting the Ohm Walsh Model F, posted when I first obtainted htem, I disucss the rehab process and my discovery of how much of a benefit it was to remove half the stuffing from inside the cabinets. 

What specifically did you do with the Walsh 4's? 

Hi Doug,

My experimentation with the 4’s started in 1998 when I sent in the cans for a re-foam. At that time I noticed that the ’tufflex’ inside the cabinet was disintegrating.

I contacted JS at OHM and he said to go ahead and experiment with different batting material; my wife makes quilts now and then so I used that batting at first. That material was less dense than the tufflex so I used about 1/2" (two layers).

The original ’cradle’ that held the tufflex was ’U’ shaped made up of two nylon straps held in place inside the cabinet by 2" wide duct tape.

JS had told me that the straps should be placed 1/3 of the way down the cabinet and that the batting should be well tucked into the corners.

My first experiment was to lay the straps flat 1/3 of the way down as opposed to a ’U’ shape still using 1/2" of batting. I was shocked by the difference; more bass and treble but slightly recessed mids. mid/bass on voices was not neutral with chesty male voices and veiled female voices.

Out of curiosity I decided to use 1" of batting on the flat straps. More but sloppier bass, attenuated treble, sounded like a cheap box speaker and the mid/bass was a disaster.

My speakers are in the basement on carpet with thick dense under-padding layed over a cement floor. Since the vent is at the bottom I know this affects the overall SQ. With that in mind I placed the speakers on 1/4" acrylic plexi-glass (16"X16"). Well that certainly brings out the bass but I found the overall sound to be too live with too much reverb and accompanying listener fatique.

Back to the drawing boards. A few years ago my wife bought some batting for Christmas decorations i.e. snow on mantles look. This batting was thinner but denser than the quilt batting. So I decided to play with that.

I quickly realized that this new batting enabled me to dial in nuances that the other batting couldn’t. This stuff is just over 1/8" thick. I experimented with varying layers from one sheet to six. I also experimented on the flat vs: ’U’ shaped cradle..

What I’ve ended up with is a ’U’ shaped cradle with two sheets of this new batting. The treble and mid/bass are dialed in like never before. Female voices have an air that rivals electrostats and Leonard Cohen’s baritone is marvelous. The bass is not as prominent but very well defined and tight. That said, on recordings that feature bass like Nirvana’s ’Unplugged in New York’ it sounds very well balanced.

Got the cans back a month ago (2nd re-foam). John does a good job of making sure that they’re in sync prior to shipping... and they are.

Over the years I probably have spent around 200 hours trying to dial in the 4's to my preferences.... don't know of anyone else that has done that.  OHM's newer models don't offer that flexibility as that cans are not attached to the cabinets with 4 wing nuts.  However the newer models (since around 2003+) have the vent venting to a wooden base which most likely affords more predictable SQ.  

Can't make a comparison between my 4's and newer models as I've never heard any other OHM speaker other than an F back in 1976 which absolutely blew me away.

uncleang, serious commitment to the cause! Kudos! It's fun to try tuning a speaker to optimum performance. I am not so committed to this particular speaker system, as it's an ancillary interest. It's never going to be in the echelon of the other speakers I use. Even the recently acquired Wharfedale Opus 2-M2 bookhself speakers have fundamentally superior incisiveness and cleanness, i.e. better microdynamics and without the relatively muffled character of the large paper ends of the Model F's drivers firing into the cabinet. It can be moderated, but it will not go away entirely because of the design. 

Because the cabinets are junk literally, having a rift along two axes of one cabinet, I  have thought of experimenting with using a doorknob hole saw to punch holes into the cabinets at the bottom to make ports. Could be fun! It may transform the speaker in a very good way, or ruin it! :)  I could put about three of them on the back side and see what happens. If they get ruined, so be it. LIke I said, it's not a high dollar commitment to the experience. This is for fun and experimentation. In principle I do not make vintage my attempt on SOTA. The new Model F5 is superior holistically, as seen in my review at dagogo.com 

This all reminds me of when prior to reviewing I bought piecemeal three sets of cables to do my own verification of efficacy of cables. It was a great time of learning. Cost something, but wow did it transform how I build systems!  :) 

My friend set fire to the drivers in his Ohm Fs by clipping his Hafler kit amps. College days! Never been a fan of this speaker, but I have never heard them with what I believe would be adequate power. I would think the speaker would be very limited regardless of electronics used.

Well Doug, keep us posted; and if you decide to butcher the 'F' cabinets with your hole-saw.... well that will make for some interesting reading.  Hell, you might just get rid of that mid/bass muddiness, you never know.  If it works you'll have JS scratching his head thinking 'why didn't I do that 45 years ago.

Keep us posted. BTW, love your reviews on Dagogo.