Bob Carver Approved upgrade on Originals and early ALS IIs

Much wealth can come from a few days of being around Bob C, and I want to share a bit with early Carver Speaker owners.

I asked Bob about the fact that in my earliest (of three) pair of ALS Silvers (CT woofers), and in the Originals (and I presume the first Plats, too), there are no openings cut in the rear "baffle" frame in the way they were always found in the later Silvers and Platinums. How does this effect the bass? "Not at all", said he. Then why cut them? "The solid side of the rear box toward the ribbon caused an unforseen intermodulation up in the midrange ", he said (the ribbon research had all been done with the boxes off, so the problem was missed). So I should cut out the holes in the pair that lacks them? "Yes, definitely. Better sound."

I will be doing my own soon, and luckily I have both types side by side, so by copying the measurements from the newer style to the CT type I can duplicate the cutouts. If anybody wants to do theirs, I will post a drawing with dimensions as soon as I hear from a few interested parties. There is one opening opposite each woofer, so three or four per side, depending on your model.

If you feel along the cloth cover on the RIBBON SIDE of your rear baffle and there are already oval openings, forget it: you're good. The other side is never cut out.

Robert R

Nice info Robert. Bob C. answered tons of questions ti any and all. Everybody had chances with one on ones.

-the oval cutouts came on the mk4's



-you just do not believe about ct woofs...OK

This is a new one for me. I would like to see some pics if they are available.

It's new for everybody, I'd imagine; that's why I posted it. Only noticed it because, being even crazier than most on the Forum,
I own THREE pairs of ALS Silver edition speakers, and noticed the difference. When I asked Bob about it he said "It's because I f...€d up." You've gotta like a guy like that. Then he told me why they cut the openings, I'm guessing starting sometime in 1988. My serial number 282 has no cuts, but by 742 they are there. I'm guessing that some early Plats are the same - all the changes seem to have been applied equally to the two models throughout the run.

There is nothing to see, on the outside. You have to feel for it on the cloth-covered rear box that surrounds the woofers and crossover. If the side toward the ribbon (call it the inside) feels the same as the side away from the ribbon (call it the outside), i.e. solid wood under the cloth cover, then that speaker doesn't have the cutouts. If on the inside edge you feel oval openings under the cloth, roughly 2-1/2 inches by 10 inches, one beside each woofer, then you have the newer, improved arrangement and can ignore the whole business.

As I said, I'll be posting a drawing with dimensions, as soon as I get time to pull mine apart and do the measuring. Not sure what kind of a job it is to remove and reinstall the cloth, but obviously you don't want to cut that out! I don't have a camera, but I plan to get one soon, so maybe I can take and post some pictures as I go.

Robert R

-robert; did you buy the oval vented silvers new ???

-it almost seems that they were mk4's that a previous owner replaced the x-overs on [to non-mk4]


-do they have a 2x2 binding post 'cut-out' or a 2x6 ???


-hmmm

Yes, bought 'em new late in 1990; they're maybe a bit older - the pair was a dealer's floor demo model for a time, and the manual is copyrighted 1989. Serial number 0742TG. Binding posts cut in so far that mostly what gets binded best is your finger and thumb. Woofers reverse-phased. Crossover identical to the type shown on p.11 of the manual posted on the Forum, except C-2 in mine is 300mf, not 175. Apparently these and also the CT versions (with quite a different crossover, in mine) were considered to be the "Mark I" type, though they were never called that, 'cause nobody anticipated the tweaks to follow, I suppose. But clearly the later ones of even this earliest group had the side cutouts.

Never saw a Mark II, but I understand it had two adjustments (mid and high), and the bass Q was changeable by inserting different resistors (provided) into some sort of socket in back. More series resistance, lower Q. Don't know if the woofers had been re-phased yet in those, or how the binding posts and controls were laid out.

The three-control types started with the Mark III's; these for sure had the woofers in phase with the ribbons. There weren't many of them made before Bob did a final tweak to make the sounds in the center a bit clearer, and that final version was called the Mark IV. I have a pair of those (originally sold 2/92), and can send you or anyone who's in need a sketch of the circuit. Problem is, the inductors (by now eight in all) are only identified by part number, so to duplicate them is a pain.

I don't know what you are working on, of course, but I hope this helps.

Robert R

-ive owned maybe 6 diff pairs of silvers...checked-out/ listened to 6 more

-from very low to higher serial #'s...

-im only familiar w/ mk4's and 'non' mk4's [just the 2 types]

Know what you mean - I've never seen the others either. The IIs and IIIs seem to be pretty rare - couldn't have been built very long. But they definitely existed, at least in the Platinum edition. (Anybody out there that has a pair, please jump in - we're trying to get all the data into the Forum). Bob (I suppose it was he) kept tweaking the crossovers, I guess around mid '89 through early '90, until he settled on the Mark IV types that saw out the run.

I know of the others only from old reviews, seven of which I rediscovered recently in a compendium that Carver printed in late 1991. (Soon I'm going to start scanning all that info to Tim for posting on the Forum.) The one by Peter Aczel from "The Audio Critic" #14 (written by late 1989 ?) covers the then-new Mark II Platinums (with two adjustments and optional Q-lowering resistors in back, but with the woofers still reverse-phased to the ribbons), and mentions "a small improvement [in the] new grille-cloth frame for the back of the woofer array, designed to eliminate residual interference with the rearward radiation of the ribbon". Apparently the first Plats he reviewed were an early production (maybe even pre-production) pair that hadn't got the cutouts, but there were many "Mark I" (Silver and Platinum) pairs that did; I checked Skip's plats at the Fest; no rear controls, but his inner frame sides are cut out, like my silvers of the same vintage. Wish I'd noted his serial numbers. (Incidentally, for my ears, Skip's setup had the best sound I heard at the Fest, even while operating in a far-less-than-ideal location.)

More on this on-going project as I get it

Robert R

Update to all interested in the modification:

I'm finally getting to the project with my early production Silvers. Have the measurements taken (from a later pair) and the covers off, but the problem now is to preserve the cloth covers when cutting out the openings in the boards that they lie against. Can see no way to cut right up to the cloth and not wreck it. About a hundred little staples hold the cloth on, just on the one edge, and they will have to be removed by hand, one at a time, I guess. Staple replacement won't be easy either - the composition board is very hard material, and the staples are the special, short type (you'd never shoot a long one into this stuff!).

Had thought to cut with a Forstner bit, but have none available big enough (the slots measure 2 and 9/16" wide, to be cut in a 4 and 1/4" board). Such a bit costs a good $36.00 - that's six bucks a slot - hardly worth it. So it's a hole-saw job, I guess; we'll see.

No hurry anyhow; there's no interruption in music. The speakers sound great without the covers on the back; as Bob said, the bass is unaffected. Amazing.

I will post all the exact dimensions when finished, for Silvers. For very early Platinums that were not cut and for all the Originals, we will need for someone with Platinums that are cut to measure those slots (four per speaker, in this case) and post the figures.

I strongly suspect that they will be the same width as the Silvers, but the lengths and spacings vary even within the Silvers, so we'll want it to be pretty exact. Don't want to create any unforseen problems; the whole idea of this project is to eliminate one.

Robert R

Update to all interested in the modification:

I'm finally getting to the project with my early production Silvers. Have the measurements taken (from a later pair) and the covers off, but the problem now is to preserve the cloth covers when cutting out the openings in the boards that they lie against. Can see no way to cut right up to the cloth and not wreck it. About a hundred little staples hold the cloth on, just on the one edge, and they will have to be removed by hand, one at a time, I guess. Staple replacement won't be easy either - the composition board is very hard material, and the staples are the special, short type (you'd never shoot a long one into this stuff!).

Had thought to cut with a Forstner bit, but have none available big enough (the slots measure 2 and 9/16" wide, to be cut in a 4 and 1/4" board). Such a bit costs a good $36.00 - that's six bucks a slot - hardly worth it. So it's a hole-saw job, I guess; we'll see.

No hurry anyhow; there's no interruption in music. The speakers sound great without the covers on the back; as Bob said, the bass is unaffected. Amazing.

I will post all the exact dimensions when finished, for Silvers. For very early Platinums that were not cut and for all the Originals, we will need for someone with Platinums that are cut to measure those slots (four per speaker, in this case) and post the figures.

I strongly suspect that they will be the same width as the Silvers, but the lengths and spacings vary even within the Silvers, so we'll want it to be pretty exact. Don't want to create any unforseen problems; the whole idea of this project is to eliminate one.

Robert R

Any new information/reports, Robert R? (I bumped this and also reported the spammer in the midst.)