testimonial - rich morin

THE RENOVATION OF A MODEL 2 - THE STORY

[A little intro: Richard "Rich" Morin is a childhood friend of the Beveridges; his father was a close friend of Rick's father, Harold Beveridge. In fact, Ed Morin was involved in the development of the speakers and knows their innards pretty well. Rich was among the first to receive a pair of Model 2s, back in the 70s; they have thus provided faithful service for three decades. What follows is the story of that pair's rejuvenation process at the factory, carried out under Rich's own watchful eye...]

PART 1

After I hooked up my Model 2's to the renovated amps (complete with re-lubricated fans :-), I started to notice some problems. One unit had distortion that got worse as the volume level rose; the other unit didn't play at all. I made a run down to Bob Hoover's house and established that the amplifiers themselves were fine; the line sources, on the other hand, were obviously having some serious problems.

Meanwhile, I had heard the performance of a pair of Rick's new line sources, as well as that of a pair that he had refurbished for Bob. Frankly, I would have asserted that Beveridges could not perform at that level, so I was _quite_ impressed.

Knowing what my speakers _could_ sound like, I was very strongly motivated to get mine fixed up. So, when Rick said that he could refurbish my Model 2's, I took him up on the deal.

I thought that some workshop time in Forestville might be fun, so I wandered up to kibitz and lend a hand. It _was_ fun, but it was also a LOT of work. The renovation is not cheap (get the price info from Rick), but that's because it requires days of tricky and demanding work. Here is a rundown of the things we (well; mostly Rick :-) did, and why...

• initial clean-up

  My speakers are still pretty clean, and the second set of grill foam was never replaced after it disintegrated, so all we had to do in this stage was to remove the glue-laden aluminum border rails that bracketed each set of lenses.

• Remove cabinet backs

  This required the removal of 26 screw assemblies (screw and cup washer) per cabinet, but a power screwdriver made short work of the job.

• Evaluate transducers

  This required disconnecting the transducers from their normal (parallel) wiring, then testing their electrical characteristics (e.g., mylar continuity, capacitance, and flopover voltage). Most of the transducers, predictably, had lost some mylar tension, resulting in low flopover voltages (e.g., less than 4 kV); a few had corrosion near the mylar contact area and/or capacitance imbalances (in terms of Rick's new, more stringent requirements).

• Remove transducers

  Each of the six transducers was bolted in by 12 fastener assemblies (nut, lock washer, flat washer, and bolt). No power screwdriver was coming within sight of these babies; I removed each one by hand! Many of the bolts were recalcitrant, but persistence paid off eventually, with all six transducers sitting in a rack, individually enclosed in numbered plastic bags. I should note, in passing, that my set appears to be the seventh set of production Model 2's, using the original "resin rims".

• Disassemble transducers

  This required the removal of 38 fastener assemblies (nut, lock washer, and bolt) per transducer, but none of them resisted very much. (Careful Reader will realize that we removed some 350 bolt and screw assemblies in these steps.)

• Rebuild transducers

  Rick then inspected the electrodes, looking for (and fixing) a variety of problems (e.g., cracks, foreign matter). After he performed the needed cleaning and repairs, we:

  re-evaluated the electrodes (against a sheet of stretched mylar), looking for capacitance or voltage-related issues; any problems were repaired as they emerged, so clean sets of electrodes were (eventually) produced.

  re-assembled the transducers, stretching and gluing in a mylar sheet, putting back the bolt assemblies, re-testing the electrical characteristics (just in case), etc. The original fabrication technique relied solely on the bolts to clamp the rims together on the mylar; Rick now adds occasional dots of super-glue on _one_ electrode rim (between the bolts) to prevent mylar slippage. At the end of this stage, the rebuilt transducers were again sitting in their numbered bags in the storage rack and it was time to get back to the cabinets.

• Rebuild cabinets

  The original Model 2 cabinets were, apparently, intended to act somewhat like the shell of a string bass. That is, the walls of the cabinet were not made solid (or even very stiff); rather, they were expected to vibrate. Although this produces a mellow, diffuse bass boost, it does really awful things to the accuracy of the lower frequencies.

  Rick proposed that we seal up major air leaks and stiffen up the critical portions (e.g., fronts, sides, and backs) of the cabinets. He also proposed that we stiffen up the outer two "wave guides" of the lenses.

  Having heard Bob's renovated 2s, I was quite eager to have this done. The actual work was pretty mundane; we pushed epoxy putty into the gaps between the lenses and cabinet fronts, inserted (dozens of) glued sticks into strategic places, and coated the outside of the lenses with a sand-filled polyester-resin "mortar".

  Whereas the original coating (sand-filled automotive undercoating) damped the vibration of the wave guides, this mixture makes them totally rigid. Considering that the air pressure in the "neck" of the lens is about ten times that at the electrode, this is quite important.

• Remount transducers, etc.

  Bolting the transducers back in, re-attaching the wiring, closing the cabinet backs, and testing out the results is the last stage. Not too tricky; just careful work...

How do they sound?

Well, as I ran out of visiting time, I don't yet know. Rick is still working on the cosmetic touch-up, so I won't get my line sources back for a few more days. By careful filling, sanding, and painting, Rick hopes to make the cabinet's lens fronts quite presentable, even with no grill foam.

This clean-up is important to me because I am unwilling to put any more grill foam on my systems. The grill foam comes apart, leaving behind residue which gets into the transducers. I also have Bob's word that the foam (like all other grill material he has tested; SIGH) is NOT acoustically transparent. So, the foam goes...

In any case, I hope to have the renovated systems playing in a week or so. I will then post a note (Part 2) telling the list how the speakers sound, look, etc.

If you live near the San Francisco Bay Area (or are around for a visit), I'd be happy to have you come over and listen to them (please call first :-). I don't have Bob's level of drive electronics, but I still think you'll be amazed at the clarity and sound levels of refurbished Model 2's.

If you decide that you, too, can't live without the renovation, send Rick a note. He is ready to take on as many of these jobs as he can; good-sounding Beveridge systems are his best possible advertisement!

PART 2

Sorry for the delay, but:

• The cosmetic issues and some re-engineering of the mylar connection scheme took Rick a couple of weeks to finish.

• Finding time to listen carefully to the systems has been a bit of a challenge; finding time to write this note has been another.

In any event, the refurbished Model IIs are happily ensconced in my living room. I have listened to several favorite CDs on them (e.g., Joni Mitchell, PP&M, Christopher Parkening, and Dave Brubeck) and am pleased to report that they are vastly improved.

The most noticeable area of improvement is dynamic range. They now play louder than _I_ find comfortable, so I won't be hitting any real limits in actual use. For test purposes, however, I ran them up to the point where the amps started to distort.

As expected, the transducers had no problems at all with this; as noted in Part I, Rick had stress-tested each of the electrodes up to 5 KV, fixing any hot spots he detected. So, they're solid!

I then started doing some serious listening. The bad news is that some recordings now seem a bit too "bright"; I may have to do some equalization to make them comfortable again. All of this reminds me of Flanders & Swann's wonderful song on the perils of Hi Fi, "A Song of Reproduction":

I had a little gramophone;
I'd wind it 'round and 'round.
And with a sharpish needle,
it made a cheerful sound.

And then they amplified it;
it was much LOUDER then.
And you sharpened fiber needles
to make it soft again ...

Careful Reader will realize that most of the material I have been trying out is vocal. Part of the reason for this is my own taste, but there is also an analytical motivation; voices are hard to reproduce well and humans are very good at knowing what voices "should" sound like.

In any case, the refurbished speakers are reproducing vocal music like a charm. In fact, I have been able to understand some words that have been eluding me for years. As I can't imagine that my hearing has somehow gotten better (:-), this must have to do with improved sound from the speakers.

I also find that some old songs seem to have renewed emotional "punch". I think this is because accurate reproduction enables me to "connect" with the singer's sincerity, but that's only my naive theory. The bottom line, however, is that the music grabs me more than it has in years.

Oh, yeah; the cabinets. Rick did a light refinishing job on the (walnut) cabinets, making them glow as they haven't since I got them. He also worked for several days on the lens fronts, making them look as if they were _supposed_ to be seen. This is in line with his practice on the new models, but bringing the old ones up to snuff is a LOT harder than simply making them look nice in the first place.

I can't guarantee that your speakers can look showroom-ready again, but I am quite willing to predict a very noticeable improvement in their appearance, regardless of their current condition. I would also be willing to predict that you will be stunned by the sound they will make, if they (like mine) have been just "limping along" with loose cabinets, faulty connections, loosened mylar, etc.

-r