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DavidR

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  2. The 12 Most Significant Loudspeakers of All Time

    in Acoustic Research

    Posted

    9 hours ago, AR surround said:

    Thanks for posting this article, David.  If I recall correctly, you have a pair of 901's.   If you have the time, would you mind sharing a few thoughts about them?  I've only heard them used as "whatever" with all the front drivers pointing outwards at some wedding, etc.   My cousin said, "The music's everywhere but the highs are nowhere."

    I'm laughing right now because of the thread title: The 12 Most Significant Loudspeakers of All Time.  That's so because I am a surround sound lunatic with 12 speakers installed in my system, including five bookshelf speakers in the ceiling for Atmos / Auro3D.

    Yes. I currently have a pair of the series 2 - acoustic suspension. My 901 story, begins approx 1970 with my first pair of speakers - Fisher XP65s. A decent 3-way design. Bose is headquartered in Framingham, a few miles from my current house and not too much further from where I grew up. I really wasn't aware of the original 901 (series 1) but in college a friend had a brother in-law that was a manager and we were able to go for a tour when the series 2 was being made. I was able to get a pair for cost. I liked them but my 45wpc amp did not and soon bit the dust from severe clipping. Moved up to a 150wpc Carver receiver. Back then loud was good.

    As Gene K said, its hard to find a room where the boundaries are perfect for them. Some time after college I bought my first home and it had a play room in the basement and I hung them from the ceiling. Damn near perfect for them. Soon after one of the speakers developed a buzz. I took it to the repair center not too far from my home. By the time I got home they had called and found the problem. Unfortunately they used drivers destined for the series 3 that had foam surrounds not the cloth surrounds that last forever. This happened near the end of the series 2 run. It was ~15 years after purchase and Bose gave me a choice: (1) install new drivers (18) at a cost I do not remember or (because they, Bose, felt somewhat responsible) I could get a new pair of series 6 for cost - $350. This, I thought, was a great deal as it was much less money than replacing 18 drivers. I did not like the series 6 too much. The highs were a bit better but the bass suffered as a result. I kept them for a number of years and got tired of occasional port chuffing and sold them after picking up a pair of series 2. I had DHS Speakers rebuild the EQ with Sonicap and silver mica capacitors and some new resistors and a few other components.  The speaker service claims Bose used cheap components back in the day and many of the high signals were unable to pass thru. The difference is very noticeable BUT they still don't have the detail of my AR speakers.

    Out of all my speakers everyone wants to hear the 901's. The bass is not as deep of a bass as my 9's or 90's but is easy to get/hear at low volumes. Everyone, upon hearing them ALL say "my God, the bass". I had one guy walking around the room looking for a sub woofer. They work well with watching movies and I listen to them every Sunday morning. The current family room is very narrow and long and getting them set up as designed would be impossible so I just turned them around and have them direct on one face and reflect off a wall on the other face.  There is something about listening to a full range driver (to me anyway). I always want to have a pair.  They are not for everyone. As for the highs keep in mind most males were never able to hear 20kHz and as you get older most of us top out at 15kHz or lower. All tuners top out at 15kHz. There just isn't much music up there beyond that. It's more about the lack of detail. I recommend the EQ  rebuild for anyone who have a pair.

    <edit:add> An after thought: they are insensitive to power as long as it is clean. I had a modified Carver amp (M1.0t Mk2 Opt2 with 460wpc) where a transistor that was part of the mod 'let go' and allowed 70VDC to hit one of the speakers (ser6) and reset and do it again. The speaker/drivers suffered no damage. They are tough to kill and will last years if cared for.

  10. For sale - Vacuum Tubes

    in For sale / Wanted

    Posted

    On 3/24/2022 at 8:32 AM, jbryan88 said:

    I'm interested in your RCA 12au7s. Are they still available? If so could you send pictures and your price is more than reasonable.

    Thank you

    J. B. Teague

    Yes, the 6680 mobile communications grade. Attached is a picture of them.

     

    RCA 6680.jpg

  12. Refoaming Acoustic Research 310HO

    in Acoustic Research

    Posted

    This model does not show up on Apheno's list which goes up to 1998 with the AR303A. This may be the reason for no posts. Most of us are not familiar with this model.

    Here is the history of AR:

    In 1967, Acoustic Research was bought by Teledyne, Inc., and for the next 22 years it continued development and operations in Cambridge as Teledyne Acoustic Research. Technological breakthroughs during this period included the high-current amplifier. When purchased by Teledyne, AR was the world's second largest supplier of branded loudspeakers. Although Acoustic Research continued product development, by 1989 AR had dropped to fifth place worldwide, and Teledyne sold the company to their major competitor, Jensen Electronics. In 1998, Jensen, including AR, was sold to Recoton Audio Corporation.

    Under both Jensen and Recoton, the AR brand continued development in the speaker industry, including the environmental controls that allowed a speaker to be placed in different room areas, the Acoustic Blanket that minimized diffraction and interference in speaker baffles, and a speaker line designed to complement home theater and the digital technologies of the 1990s.

    In 2003, Audiovox (now Voxx International) acquired the U.S. audio operations of Recoton, and continues with AR-brand speaker development and sales. An associated firm, AB Tech Services, provided maintenance of AR speakers until mid 2014. Web-based audiophile communities lamented the closure of the company and apparent liquidation of stock. As of July 2014 CM Tech Support assumed responsibility for Acoustic Research parts and service.

    So these were probably made after 1998 by Recoton. Hopefully someone will come along who has some knowledge on them.

  17. AR 58S Rebuild

    in Acoustic Research

    Posted

    I'm wondering if he's happy having (what looks like) used NPE (except for the 4uF). I beginning to think this might be best for the old ARs to sound like they were intended to. I used NPE in my 90s and 10Pi rebuilds with a small poly cap in parallel on the series caps and am very happy with those results.

  19. For sale - Vacuum Tubes

    in For sale / Wanted

    Posted

    TUBES FOR SALE

    - All tubes have been tested on my restored Sencore TC142 for shorts, grid leakage and emissions.


    > Tung-Sol 5AR4 Rectifier, used – tests new. 113/113 emissions. $25

    > Genelex GZ34 Rectifier, New/never used. Was my back-up. $40

    > (2) Tung-Sol 12BH7A, shiny black plates, halo getter, date code Dec. 1960, test 107/107 and 106/106, Original boxes. $45 each

    > GE JG-5751 military issue (12AX7A/ECC83) with triple mica, grey plate, O-getter, tests 96/97. $35

    > Telefunken 12AX7, diamond on bottom, logos worn off, gold pins. Used but tests NOS 105/105, repro box. $105

    > Webcor by Mullard 12AX7 I61 BOH (rare), repro box. Used but tests NOS 106/104. $80

    > (2) RCA 6680/12AU7A communications grade. Dark grey plates, halo getter. Original boxes in fair minus condition. Measure 98/98 and 98/98. $30 for the pair.

    > Mullard CV4003/M8136 (12AU7 alt). British military issue, original box. Used but tests NOS: 96/96; $90


    >> Contact me (via PM) if you want shipping cost and/or pictures of a particular tube.

    PLEASE DON'T WASTE MY TIME WITH RIDICULOUS LOW BALL OFFERS

  22. AR 3a need of changing the capacitors ?

    in Acoustic Research

    Posted

    On 12/11/2021 at 7:59 AM, FluAR said:

    I already tried on one with new PP Dayton, sound has changed a little but not for the better, maybe they need break in ?

    Dayton is a low end film cap. Time might help sound better. Do not be afraid to use NPElectrolytics. I believe F&T and Mundorf Ecaps (made by F&T) make caps in Germany . They are a well made NPE. Should you want a bit more detailed high end then add a quality 0.01uF film bypass on each series cap by paralleling them. I did this on my AR90 and 10Pi and I'm very happy with the sound.

    Old NPE caps start acting more like a resistor than a capacitor.

  23. AR 3a need of changing the capacitors ?

    in Acoustic Research

    Posted

    On 12/21/2021 at 4:30 PM, FluAR said:

    OK,

    but why did the capacitors have a + sign ?

     

    FBBF18CE-FC13-4611-93B5-AAF494E32FB7.jpeg

    Crossover caps need to be non-polar as the current has to be able to pass in both directions. The reason for the (+) is it probably indicates the inner foil and should connect to the destination (driver). All of the 2500uF caps in my 9s and 10pi have the (+) and they are all connected to the driver/red wire marked + on the driver.

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