ReliaBill Engineer

Duplicate post…

Which I guess speaks well for the durability of the woofer mechanics. The voice coil can’t shed heat fast enough, and 30-1000 Hz is where the majority of music power is. Looking at the suggested wiring of the fuses, it doesn’t protect the tweeters by themselves. The fuse is seeing the total current fed to the loudspeaker. So is it going to protect the tweeter? Kind of doubtful. It’s a crapshoot whether enough current still passes to the tweeter to blow its VC before the fuse blows.

I don’t think a fuse would have protected your tweeters from the sudden *thump* of a mic input:

I’m thinking of buying a pair to play around with. Harshness comes from distortion. So have to reduce the distortion.

IMO, yes, those caps need to be replaced if original. A fuse could be added, but putting inside the cab would be a pain to replace if you blow it. I’d put it outside on the terminal plate with a fuse holder clip. Some audiophile purists would say to never use a fuse in a tweeter circuit; but these aren’t $100,000 Wilson Audio speakers, either.

Last pair of 4x tweeters I worked on had the same issue. I used an Exacto knife, new blade, to cut the glue holding the paper cone edge. Then removed the solder from both terminals. Desoldering braid worked for me. Then I cut one remaining lead. Lifted out the cone+ voice coil. Checked coil condition and continuity. Both were good. I soldered extension wires onto the originals. Threaded the extensions into the terminals. No solder yet. I then ran a small bead of thinned black RTV under the edge of the cone, centered it. While still moveable, I used a 1.2 volt battery cell to energize the leads, to center the VC. Then pressed the cone edge into the glue all around. I rechecked the centering by using the battery cell. No scraping sound. I let the glue cure. Then soldered the wires to the terminals. Pretty much what I do for repairing dome tweeters also. I like using thinned RTV because it’s reversible. If I find that I goofed, an Exacto blade can be used to cut the glue and start over. AR was fond of using fiberglass batting to damp mids and tweeters.

I’ve been comparing a new pair of KLH 5s to my fully refurbished 1965 AR-2ax speakers. Hands down, the 2ax’s are preferable. The 5s do have slightly lower bass. But in other areas of imaging, “air”, realism, FR “balance”, smoothness and extension of treble, vocals, the 2ax’s really shine!

Did you have the original diaphragms and voice coils? If not, what did you use as replacements?

True. But it’s difficult to address distortion from mechanical degradation issues when the VC windings are bad, reading discontinuity from being fried or severed. Mechanical degradation becomes secondary to a bad voice coil. This mid driver read “open circuit”:

I usually remove the drivers from the circuit, then test the drivers using a DMM set to 200 ohms. This tells me if the VC has continuity and at what DC resistance. The DC resistance tells me what impedence range the driver is in, 2/4/6/8 ohms nominal. All necessary to repair or replace the driver.

One of the mids, after arrival:

Alas, no. Neither mid has the dome+VC. I wound up getting a “forced” refund from the seller. I asked him prior to purchase what the DCR was of each. He said “open circuit”. But he failed to say that neither one has any wires to measure from! eBay agreed with me, that the seller was deceptive in his description and communications with the buyer (me). Since then I have the raw domes, but need the VCs. I may wind up having to make my own VC formers, and winding them myself. I have kapton. I have various spools of wire, 24-36 AWG. But not sure I want to go that route.

I’ll be rebuilding these early AR/3a dome midranges. Open circuits, per the seller. Once complete, I’ll use them to compare sound to the 2” hard dome midranges above.

Great news!! I have a pair of AR-3a dome midranges coming my way. They need repair work done. I’ll document the repair. Then I’ll compare to my dome midrange “mod” for the 2ax. This will be my 3rd pair of 1965-1969 3a dome mid repairs. The other 2 pair got sent back to their owners locally (in state). This pair is mine.

The light beige looks just like my original cloth grill on my 2ax. Very difficult to see any difference.

Sound deadening. Acoustic damping inside the speaker cabinets. I’m working on an interesting project at work that pertains to this. Artemis IV has a “hollow” tubular section 33 feet in diameter, 40 feet high, 34,194 cubic feet volume, where computer modeling shows it to have destructive levels of acoustic resonance. In essence a huge bell, or a volume that will build up acoustic vibrations from air passing over the outside of the volume at very high velocity. Modeling shows the acoustic vibrations to build to a level shown to be a structural hazard both to the section as well as to the avionics and structures within the volume. The solution has to be low mass, low volume, and fire proof. Frequencies 10 Hz to 10 kHz. 30 dB of damping.

Original tweeter, woofer, crossover capacitor values. These have the sound I was looking for. Airy, clear. Not “laid back”, but very musical over long listening sessions. Perfect for my tastes.

I’ve been/am very happy with these ‘65 AR-2ax speakers. They are musical, and just great to listen to. These are now in my workshop in the garage, getting some needed cosmetic attention. Listening to some Bonnie Raitt: Finished my listening sessions. Now to fully incorporate the much better midrange drivers, while keeping the AR motif. Auditioning a new cartridge and stylus:

I’ve been/am very happy with these ‘65 AR-2ax speakers. They are musical, and just great to listen to. These are now in my workshop in the garage, getting some needed cosmetic attention. Listening to some Bonnie Raitt: (Wife not happy in the kitchen. James Bond on TV….)

The original foam is soft polyurethane foam. Medium density open cell. Finding it in black is the problem. But, probably available on eBay.

Comparison. Original paper cone mid and the dome. Original: Dome midrange:

I have a bearing press. I already have the forms made. Using a propane burner to anneal the titanium. This alloy can be softened; otherwise it would crack badly when put through the expanding dies.

The expanded titanium arrived today. Very comparable to the original aluminum.

I’m very happy with the sound of these at present, using the original woofer and (super)tweeter, and 4/6 uF capacitors. With the 2” dome mid, it has everything I want. Surprisingly, I’m having a really tough time sourcing the expanded aluminum guards for the mid. 1/2” x 1/8” diamond opening, 18-20 gauge thickness. I plan to replace the perforated steel guard currently on these domes. Just to keep the AR appearance. I’ve ordered expanded titanium from China. Closest I could find. Using this dome midrange/tweeter, I found that it, too, needs to be wired just as AR did, out of phase polarity-wise, to get a smooth transition. The tweeter domes don’t go way out to 20 kHz. But the end result is a hugely pleasing easy, comfortable, effortless sound that I can listen to all day with no regrets. In my opinion, I’ve done the least amount of molestation to these old girls, while improving the sound, yet keeping the old character. The 16 ohm pots, 6 uF caps, with the new domes and small 0.1 mH smoothing inductor at the dome terminal, helps to control the dome nicely. Whether at very low listening level, or much higher volume, the speakers just sound GOOD to me. No matter the age of recording, nor genre, they are a relaxing, good listen! My wife prefers listening to her CD collection vs my vinyl collection. Yesterday was her day. Trisha Yearwood, Bonnie Raitt, The Supremes, The Drifters, Patty Loveless, Oak Ridge Boys, etc. She had a good time!

And performance? Sound, characteristics, plots, tests?