fedeleluigi

As I wrote in that thread, for the AR 10 Pi the Italian magazine said the switches were set for the maximum output (4Pi, 0dB, 0dB for woofer, midrange and tweeter respectively).

You may note the minimum impedance value on the plot of the Italian magazine is about 2.8 Ohm between 6000 and 7000 Hz while your plot shows about 1.8 Ohm in the same frequency range.

@giovanni56 Hello Giovanni, Thank you for the clarifications. If you are interested in a comparison, in the link below I posted the impedance plots of AR-11 MKI, AR-10 Pi MKI and AR-10 MKII measured by some Italian magazines in the 70's. Unfortunately, they do not say how the switches were set during the impedance measurement of AR-11. https://community.classicspeakerpages.net/topic/1408-ar-11-woofer-200003-measurement-refoam-repair/?do=findComment&comment=121942

Hello Giovanni, Your 200003 woofers show a very high FS, about 50% more than the typical (16 Hz) measure of the made in US woofers: Did you use a very stiff surround to refoam them? The values of 24.2 Hz and 23.6 Hz that your last two plots show are more typical for Tonegen woofers. I'll appreciate any clarification. Luigi

Dear Ella, I am deeply saddened by the loss of your father. Unfortunately I never had the opportunity to met him in person but only through The Classic Speaker Pages since the early 2000s. As others have said, his contribution to this forum has been invaluable and I will personally miss his presence greatly. Thank you very much for letting us know. My deepest condolences to you and your entire family. Luigi Fedele

Yes, the cone is correct! You can see other identical pictures of the Tonegen AR9LSI lower midrange on this thread (last images): https://community.classicspeakerpages.net/topic/10666-8-lmr-for-ar-9-and-ar-90-200027-availabilitysubstitutes/?do=findComment&comment=128245

Hello, Actually there is no extra inductor in the AR-90 because the AR-9 also has it! The AR-9 crossover schematic in the library is wrong. In my post linked below you can find the correct schematic of the AR-9 redrawn by me. https://community.classicspeakerpages.net/topic/11407-my-ar-9-capacitor-recapupgrade-project/?do=findComment&comment=137305

It may be that before the capacitor replacement you didn't pay much attention to the sonic differences between the two speakers. Using the 8.2uf polypropylene cap in parallel with the midrange may have altered the damping and therefore the frequency response around the crossover frequency (with the tweeter). Without accurate measurements of both the capacitors you used and the recapped speaker it's hard to tell if the degradation you hear compared to the original speaker is real or not. In my experience frankly it has never happened to me that replacing the old capacitors in AR speakers made the sound worse. There is generally an improvement especially when the old capacitors are out of specification. Just follow the simple rules mentioned by Ken Kentor in the thread I linked. Personally, for AR speakers, I only use bipolar audio electrolytic capacitors (usually Bennic or M.D.L.) from reliable sources (unfortunately there are many fakes). I always measure them to select them. I never use the small bypass capacitors.

Hello Marklone, To be more scientifically sure of this difference you should swap all drivers from one speaker to another. Actually the difference could depend more on some differences in the drivers (they are around 40 years old) than on those of the crossovers. You did well. In reality during the comparison the two speakers should "ideally" be in the same place in the room (as even the same speaker in two different places in the room will sound differently). Therefore, when making the comparison, I suggest you place the two speakers at least next to each other and swap their positions from time to time. Obviously the musical signal must be the same for the two loudspeakers and not the right/left one of a stereo signal. If you don't have the mono option on your amplifier you can use an RCA splitter on your source (CD player, etc) and use only the right (or only the left) signal for both speakers That wouldn't surprise me! The ESR of the capacitors may affect not only the attenuation of the driver and the crossover point (when placed in series) but also the damping operated by the crossover filter (when placed in parallel). In other words, the use of capacitors with ESR different from the original ones can compromise the target response of the speaker. Ken Kentor (kkentor) and David Smith (speaker dave), two leading speaker designers writing on this forum have pointed this out on different occasions in this and other forums. Read for example what Ken Kentor says in the thread below about replacing capacitors.

Roy, thanks very much for replying and clarifying; As far as I know, after stopping in-house production of its 1-1/2 in. midrange (p.n. 200010-1), AR supplied a similar unit manufactured by Tonegen as a replacement part. Until circa 1990/early-1990s the part number of the Tonegen midrange was 1210010-1. Then the part number changed to 1210010-1A and this number was kept until the end of the production (around the mid 90's) of the drivers with screen and fiberglass pad in front of the fabric dome. The Tonegen 1210010-1 and 1210010-1A midranges were aesthetically practically identical and frankly I don't know what was the real reason for the change of the part number. BTW, in the same period also the Tonegen 12" woofer used as replacement part for AR-3a, LST, 10 Pi, 9, 9LS etc. changed its part number from 1-2100030B or 1210003-0B to 1210003-2A. As said, both of 1210010-1 and 1210010-1A midranges had the screen and fiberglass pad in front of the fabric dome like the original AR 200010-1 midrange. Later, before its final closure (which occurred around the mid-90s), Tonegen produced the latest 1-1/2 inch midrange (p.n. 1210010-3A). It was used both by AR as a spare part and by CELLO for its latest loudspeakers using Tonegen components (CELLO switched to Dynaudio drivers when Tonegen closed down). As said, the part number of this latest 1-1/2 inch midrange made by Tonegen was 1210010-3A. It was basically the same midrange as before but lacked the distinctive screen and fiberglass pad of the original AR 200010-1 midrange. So, it was the latest CELLO Amati, Stradivari Master and Grand Master and not the early ones to use the Tonegen midranges without screens (1210010-3A). The last picture shows this. Mark Levinson (who had founded CELLO Ltd. in 1984), one of the most skilled marketing strategists in the HI-End world, said that these latest AR midranges were an evolution and sounded better than their predecessors. Note that at the time no one (except industry operators) was aware of Tonegen and that the drivers used in these very expensive and made in USA loudspeakers were actually manufactured in the East by Tonegen itself. Personally, I think Tonegen was actually scraping the bottom of the barrel and had no more screens available for that type of midrange as they were closing down. In other words, as far as I know, the 1210010-3A was the midrange of the last batches that Tonegen supplied to AR (and CELLO) through AB Tech and that was used while stocks lasted. Obviously some vendors of AR replacement parts found themselves having both the old 1210010-1A and the new 1210010-3A in stock for some time. What I do know for sure is that, at some point, the official Italian distributor of AR (Arcona) stopped supplying the 1210010-1A midrange and started to supply only and exclusively the 1210010-3A midrange while stocks lasted. - - A young Mark Levinson with the early Cello Stradivari Grand Master using the Tonegen 1210010-1 or 1210010-1A midranges. Note the midrange screens and fiberglass pads.

Yes, it will. Measurements, if properly carried out, are always useful and, above all, objective. Thank you very much

Roy, would you mind sharing these documents with the community? I do think that every member of this forum will thank you. Me first! Thank you

In order to make things easier I attached Rlowe's files to this post. The 1027 file extention has been corrected. 1026.pdf 1027.pdf AR10pi-CircuitNotes Version 1.1 Sep2014 (1).pdf

For those who want to restore the AR-10 Pi crossover, Rlowe's files can be very useful. He did an excellent work with the last update (AR10pi-CircuitNotes Version 1.1 Sep2014) and the 1026.pdf and 1027.txt files. You can download them from the old thread “ AR10Pi crossover schematics” : https://community.classicspeakerpages.net/topic/1520-ar10pi-crossover-schematics/?do=findComment&comment=58409 PS: Note that there is an error in the file extension of the 1027.txt file. After downloading it, in order to open it you need to change its extension from .txt to .pdf.

👍This is exactly what the magazines of the time (I posted previously) wrote!