AR surround

The test only went up to 8k. Apparently, that is the standard audiology test. According the online tests I can hear up to 10k. It used to be 11k, which used to be 12k...

All of this discussion is great, but what I'm truly waiting for is an advancement that will give old ears the frequency response of that of a new born baby. (Just had my ears tested. They are just fine up to 8000 Hz. After that...)

I have auditioned several tower speakers over the years. As I've noted many times before, I find modern speakers to sound more detailed than the AR9, but in an antiseptic sort of way. Also, these speakers that reveal more detail...well, they can be absolutely grating and unforgiving when playing many re-mastered redbook CD sources. No wonder vinyl has made a resurgence. A number of years back, I had the opportunity to A/B a pair of AR9's with KEF 105's. Which did I prefer? It depended on the program material: for classical music I preferred the KEF, for pop/rock I preferred the AR9. But both of these systems were wonderful and probably still are. Many people like the B&W speakers for the characteristics that you have noted, David. Yet others complain of listening fatigue with B&W speakers. Weak bass can make the highs and mids sound somewhat clearer. I've been remixing songs using DeMix Pro. I have used it in some instances to extract the bass stem, boost it, and remix it into the song. Often, more than a judicious amount of boost to that bass stem diminishes clarity. This reminds me of when I auditioned Revel F32 floor standers. Really nice clarity (antiseptic, though.) I mentioned to the salesman that they lacked low bass. He said that they needed one of those $3000 Revel subwoofers. Sheesh! 😂

The AR18 is arguably the most remarkable AR speaker that I have ever heard...a wee speaker with big ambitions.

I agree with your comparison. I had an opportunity to audition a KEF 105 vs the AR9. The KEF 105 was very precise, etc etc. I found that I liked the way it handled classical music more so than the AR9. The moveable heads really had that 'cool' factor and accommodated optimization for the sweet spot. However, when switching to rock / popular music I preferred the AR9. I do not care that the AR spec calls for placing the AR9 against the back wall, etc. Mine sound much better and more 'holographic' and with more depth when pulled out into the room and toed in towards the main listening position.

Are you going to update the SPICE diagram to reflect that both speakers have the same inductors? I ask because I am using AR9's as front speakers and AR90's as surround speakers in a home theater setup. I had to add some additional series resistance to the tweeter and UMR of the AR90's to achieve a response closer to that of the 9's.

AR owner since 1972: AR5, AR3a, AR7, AR9, AR90, AR48, AR915 I personally would not spend a lot of money on a vintage speaker for the collector's value. I would rather buy new. Of the ones mentioned in the article, I've only heard the Vandersteen 3A. They are very nice speakers. Every "modern" speaker that I've auditioned has very impressive, detailed sound..but I would describe it as more antiseptic than musical especially with digital sources. Perhaps my ears are tuned to the sound of the AR9 series. That is fine with me.

Sorry that the ECaps didn't work out for you, Kent. Perhaps I should have mentioned that I paid $1 per capacitor for precision matching by Sonic Craft. But that was over six years ago now. I bundled the 22uF and 2.2uF caps for the UMR on my AR9's and AR90's. I found the packing slip this morning with the measurements:

While I understand that it isn't easy to move these speakers around, have you tried repositioning them? I once had my AR90's placed relative to my listening position that turned out to be a bass null which yielded unacceptable results.

Each AR-1 speaker had a list price of $185 in 1954 when it was released. (I don't know about discounts.) That's $2086 per speaker in today's dollars. It was a good chunk of change back then. So these asking prices for 70 year old antiques seem absurd. I guess it is the high collector's value. https://auralfetish.com/pages/acoustic-research

When you find original Sprague caps that no longer meet spec, what do you select as replacements?

If there are two 'audio visuals' that I love, they are blue VU meters and the glow of a tube amplifier in the dark. Alas, I have neither.

And it's interesting that the stuffing does not go down to the level of the woofers in the AR9, but rather is installed in the space above the woofers.

Gasp! That price is unimaginable. Gee, I really should have picked up a pair in 1954 and put them into humidity controlled storage. Of course, one has to have been around in 1954 and not just a gleam in their father's eyes.

Glad to hear that things have ended up well. If you like the way your recapped speakers sound, you might not want to challenge fate and drive yourself crazy in the process.

Other's who have measured that ESR might be able to answer that question. However, as implied in other posts above, you should be able to effectively raise the ESR of those series capacitors by using the attenuation switches. A 3dB reduction is large and audible. A 6dB reduction is huge.

Do you mean ESR, Equivalent Series Resistance?

A few questions / observations: 1) You said that employing the attenuation switches did not seem to make much of a difference, even between the 0 dB and -6 dB positions. That should not be the case. There should be a very noticeable difference between those two positions. Something may not be right with that circuit. 2) When you went into the speaker, did you check that the wiring was in accordance with the schematic? When I got my pair of AR915's, I found that someone had previously gone in an "rearranged" the wiring. 3) Did you install the F&F bypass capacitors? 4) The caps that AR used were known to have a very high ESR. You might find it necessary to add a small amount of resistance to tune the speakers to your taste. That is why my first question about the attenuation switches is so important. When I recapped a pair of Boston A70's with NPEs, I regretted replacing the old gray Unicon caps. The A70's had no attenuation switches, so I needed to add both a 0.5 ohm resistor and then a F&F bypass capacitor to achieve what I considered to be acceptable response.

Perhaps you might want to recap one of each speaker with each option installed? Then you can compare them side by side to check for obvious audible differences. Of course, it would make sense to listen and then swap speaker locations to ensure that room interactions are not biasing the result. Another suggestion is to check the results using both recordings of the highest sound quality and those to which you mostly listen. It is my opinion that a speaker that only sounds good playing the highest quality recordings is useless if it is unlistenable with 90% of everything else.

I am curious to hear your opinion on the two options for the 24uF position after you try them out. On both of my AR9 and AR90 recaps, I ended up with Mundorf ECaps (22uF + 2.2 uF) plus the F&F bypass. All previous tests yielded very unacceptable results. However, for my AR915 (same as an AR91) center channel speaker, I have Jantzen Cross-Caps 5% MKP with 0.01uF F&F bypass caps. I haven't found the need to change those out to NPE's.

Here is the video that you are referencing. He briefly talks about using bypass caps at about 8:15 into it.

Technically, one could use a poly as a bypass capacitor across an NPE, but I've never tried it. The theory of adding a bypass cap across a main cap is that the circuit will take on some of the characteristics of the bypass cap. The 2.2uF poly as a bypass across a 22uF NPE that you have suggested seems like a rather large value for a bypass cap. @Stimpy, myself and others have used low value (0.01uF and 0.10uF) Film and Foil bypass caps across both NPE's and Poly caps with excellent results. Film & Foil caps are relatively expensive, so the thought is to add a small value Film & Foil cap to get the most bang for the buck.

Markolone, Those 2.2uF Mcaps as the "bypass" caps on the midrange are not Film and Foil caps as @Stimpyis referring to in his above post. You might want to add a 2.2uF NPE to the 22uf NPE on the midrange and then use a 0.1 uF Film and Foil bypass cap. I'm not saying that the combination that you have won't sound OK, but I know for certain that the 22uF NPE + 2.2uF NPE + 0.1uF F&F bypass combination does work. Also consider adding 0.1uF film and foil bypass caps across the 4uF and 8uF Mcaps IF for some reason you don't like the result of just using the MCaps in those positions. While the film and foil bypass caps may not be necessary on the large shunt capacitors, you might as well add them if you plan on buying the Dayton F&F bypass caps as they are inexpensive.

Yeah, I replaced the Unicons with those Parts Express caps that DavidR references. There's that "S-Word" yet again, David. LOL

I second that. I preemptively replaced the Unicon capacitors in a pair of Boston A70's with new NPE's. It turned out to be dive into a rabbit hole that required adding resistance and F&F bypass caps to achieve acceptable sonic results.