RoyC

Suitable as a replacement in the 4x, not pair of Polks. No relevance.

Hmmm, I'm sure it will be interesting, but it is hard to see how it will be relevant to the 4x. Impedance is only one parameter. You are proposing using it with a different woofer, different cabinet, different crossover...and conclusions reached based on your listening impressions?

4 or 8 ohm. Are you installing them in 4x's? What kind of changes do you have in mind?

Hi George, Based on your post, I'm sure you have plenty of sealant on the woofer and mid surrounds. As long as your woofer cones are returning more slowly. There is such a thing as applying too much sealant. The mids' surrounds only need one light application of sealant, which is much less necessary than the supplemental treatment of the woofer surrounds. It is more important to keep the mids' surrounds compliant. The most critical aspect of installing the mids is sealing their sub-enclosure from the rest of the cabinet. The mids originally had white foam gaskets in the space you filled with putty. There should be some kind of gasket material under the entire mounting flanges of all the drivers. Roy PS Great photos, Kent.

The dust cap is original. I agree with Kent. It all looks good from here, including that fancypants capacitor arrangement! 🙂 Not sure of an any upside, but I'm certain they will do the job very well. Roy

Good photo...I don't believe I have ever seen an original AR-9 woofer without the masonite ring. OP probably should post a photo if he is in doubt as to whether he has original or Tonegen replacements(s). It is important not to damage the ring if it is present.

So you have experience using this tweeter in the 4x? What crossover and cabinet changes did you make to accommodate this tweeter?

First of all, we are talking about subjective impressions of a 4x replacement tweeter based on feedback from users, not your opinion of the original AR tweeter. It should be noted that the replacement PRT type tweeter does not have the same construction as the original 4x tweeter...which has a more compliant suspension. The PRT replacement is not as capable in the mid frequencies primarily due to excursion differences. Despite this, a great many users are satisfied with it. It is the difference between this tweeter and the original AR-4x tweeter under discussion, not any flaws (or "distortion") associated with the overall use of this type of tweeter. Secondly, your conjecture as to why AR used dome tweeters is not accurate. It is not uncommon for speaker manufacturers to successfully use cone tweeters in 2-way designs. AR used dome tweeters for the highest frequencies in 3-way models to enhance dispersion and power handling, not because their cone drivers were distorting. Dome tweeters were used only in their more robust 3-way designs, never in their 2-way models. The cone tweeter used in 2-way models such as the AR-6, 7, 8, and 18 is still highly regarded. Obviously any driver used outside of its design parameters can "distort". In the end, we are probably talking about the same thing. We just have a different definition of "distortion".

I disagree. No speaker system (or individual driver) has ruler flat frequency response...so are those departures considered to be "distortion"? The 4x replacement tweeter referred to as "harsh" by some people has been found to be satisfactory others. Earlier in this thread a forum member stated "I actually like the Parts Express replacements". Are you going to tell him he prefers "distortion"? If so, based on what? "Distortion" is usually considered to be something that should not be present such as noise, static, rattles. clipping, etc. I think you are actually referring to frequency response and tonal balance, not distortion. The crossover integrates presumably properly functioning drivers to produce a desired response. There will always be variations and preferences on the part of the designer and the listener.

If it is Simply Speakers adhesive, the primary solvent is toluene. 12 inch woofers manufactured by Tonegen had a raised area stamped into the woofer basket instead of the masonite ring. Roy

5w would be the minimum. 10w or higher would be better.

As I mentioned above, the 4 ohm version is a better bet. If the mid range seems too forward, you can experiment by placing parallel resistance with the higher impedance replacement tweeter, starting at 8 ohms.

It's not unusual for some old "vintage" amps to send very destructive DC to speakers when failing (at any volume level). It can't hurt to use a basic 2 to 3 amp fast blow fuse in an inline fuse holder as some protection insurance with these systems. https://www.parts-express.com/In-line-AGC-Fuse-Holder-070-609?quantity=1

Agreed.

Interestingly, back in the shop we also saw more fried woofer voice coils than tweeter voice coils...which had been protected by its crossover components.

Not necessarily. In this case it probably has more to do with its inherent frequency response and behavior with the existing crossover.

This tweeter is certainly not a perfect replacement, especially when used in a pair next to an original. Unfortunately, there are really no other "drop-in" options. There was some experimentation with crossover changes for this tweeter mentioned in the forum quite a few years ago, but I'm not aware of anyone who implemented any of the suggestions. Midwest is selling a 4 ohm version as well as the 8 ohm version sold by PE and Vintage_AR, and I'm more inclined to recommend that one if given a choice. https://www.midwestspeakerrepair.com/product/mw-audio-mt-4107-phenolic-cone-tweeter-2/ (Btw, VAR's addition of the sealant is just an attempt to calm the harsher nature of this tweeter...with very limited success.) Roy

I strongly agree with Aadams. Andre, You are over-thinking the possible issue at the moment. After verifying the problem is confined to the cabinet (which you have done), the very first thing to do is to simply place a jumper across the fuse. It will take you just a few minutes to do this. When the LST/LST-2 fuse becomes worn out it can pass a weak signal causing exactly what you describe. I have run across this several times. The issue is unique to these models. Roy

18ga would be more consistent with the other AR coils, but if the smaller gauge is all you have on hand it won't hurt anything.

Yup...I did mention it above. Remove the resistor regardless of your approach.

Oops, sorry...I had 2ax on the brain. 🙄 There is a .1mh coil for the tweeter in the Improved crossover, so... -You could replace the coil on the back of your HiVi tweeter with a .1mh coil, which would place it in parallel with the existing crossover coil. -or disconnect the internal tweeter coil and leave the one mounted on your tweeter as is. In both cases remove the resistor. The goal is to reduce the parallel coil value for use with the HiVi tweeter. Roy PS Perhaps an easy way to start would be to simply disconnect one of the coil leads (and resistor) from your HiVi tweeters just to see how it sounds with the original .1mh crossover coil.

Install it as shown in your photo just as you would the 3a. Connect your tweeter's red lead to the crossover's yellow wire, and black to black. Some people have played around with polarity and/or have reduced the 2ax's original 4uf capacitor to 3uf, but don't change anything until you try it as is.

Remove the metal screen and try it again, as a loose screen can sometimes cause this issue. Of course, also inspect the cone for any obvious problems.

If you haven't already done so, remove the clip and tap the rivet/shaft out from the inside. You can easily replace it with a brass or stainless steel screw, nut, and washer to replace the entire spring clip arrangement. (Use brass or stainless hardware because it is non-magnetic.)

The higher impedance of the 3/4" dome 2ax tweeter makes it less sensitive than the 3a version. It will also behave differently with the AR-3a crossover.