genek

How much was "too much?"

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Dave, what's happening between 100 and 200 Hz? Both speakers show the same dip, and it isn't anywhere near the crossover point of the 4x. Is that a room effect? Does it play any role in your descriptions of the speakers' sound?

Continue discussion on Dave's AR-4x mod here. The crossover vs. equalizer discussion is now in The Kitchen.

I wouldn't necessarily expect them to be. But this thread isn't about what happens to the sound when the response is shaped with an equalizer, it's about what happens to the sound when the crossover is modded.

Nothing, that was my whole point. If there's no change in the drivers, stuffing, cabinets, etc., and the original and modded-crossover speakers are both placed identically and used to play the same recordings, it should be possible to assess what changes the crossover mods have made in the way the speakers sound, and for a listener to make a subjective decision as to whether one sounds "better" than the other. It should even be possible for a listener like me to do it, as long as the modded speaker has its HF control tuned as close as possible to the original so that the only measurable change is the leveling of the response curve. All the other items you cite as affecting sound should not factor into a comparison if they are the same for both speakers.

In this case, I would say the answer is in Dave's opinion. I would be a terrible person to use as an evaluator, because my listening preferences are decidedly bent toward the classic AR sound; I don't even care much for most of AR's own products after the ADD series. I might perceive an improvement from flattening out dips and bumps, but if the resulting speaker has a modern "flat and accurate" sound, I either won't like it or will be reaching for the HF control to dial that classic AR rolloff back in. If the original and modded speakers both have the same drivers and cabinet and are both being used to play the same recording from the same location in the same room, it seems to me that variables other than the crossover mods should have a minimal effect on the question. What would cause this not to be the case?

Yes, but all of these things are outside of the changes Dave is making in his speaker. The question is. when the modded speaker is A/B'd next to the original under the same conditions and with the same program material, will it sound better than the original?

Dave also has yet to post any listening impressions. So while all these different configurations and their curves are interesting to look at, we still don't know how the end result is going to sound when actual music is played through it.

Download "Restoring the AR-3a" from the library and check the section on level controls. The parts and procedure for replacing original pots with L-pads are the same.

I don't know about you, but being able to take a 40-year-old speaker that sold for $59 each and make it sound not much difference from a modern pair of $15,000 speakers just by updating its crossover doesn't sound like a particularly absurd limit to me. Although it probably will end up moving this thread to mods and tweaks.

40 years after the fact, there's not much else to do with them, is there? It's not as if you can just run out and buy AR's latest version at Best Buy.

Dave, when you're satisfied that you have everything just so, can you post wiring diagrams of your "final solution?" Some of us don't do well trying to figure out how to mod or build circuits based on written descriptions.

Here are the curves. From the description in the text, they appear to have been made with the tweeter control set at the Normal position. The full article is a big scan, but if you want it I'll see what I can do to reduce the file size.

I've never seen or heard the 4xa, but I do have a pair of 6's. I was wondering if any guesses could be made about the 6's based on the crossover schematic and the FR curve, which I have from an old High Fidelity article, but the 6's don't use the same cabinet as the 4's, so maybe not.

Dave, any thoughts on whether the AR-6 with its different tweeter and crossover and the 4xa that used the same new parts as the 6 was AR's fix for these issues? Or is there no way to tell without getting a 6 and a 4xa in front of some instrumentation?

It's in the original. Vincent Price and the police inspector find a fly with David Hedison's head on it trapped in a spider web screaming for help, the inspector kills it with a rock and the movie ends as they head off to clear the wife of her husband's murder.

I wonder what the stuff they use to make real flypaper sticky is made of...

Is there any indication that AR doped foam surrounds? My 1975 2ax's had the removable velcro-retained grills and, naturally, I looked inside. The surrounds were dead matte in appearance and dry to the touch from day one.

I've never owned any speakers with cloth surrounds, but when I was a kid my father used to build his own speakers, and used a speaker doping solution manufactured by GC Electronics (reddish-colored product sort of like thinned contact cement that remained tacky forever). I remember trying some of it on an early-model foam surround woofer that had a tear in it and was destined for the trash anyway, and the solvent in the doping melted the foam on contact. I suppose the obvious question raised by changes to surround coatings with age is, if the originals also changed as speculated, did the original manufacturers allow for this in their designs, and was there a typical "break-in" aging period and a projected "end of life" point when they would recommend replacement to customers inquiring about service to old products?