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Details about  INFINITY 2000A speakers, 1973—30KHz RTR electrostatic tweeters—Philips midranges

INFINITY 2000A speakers, 1973—30KHz RTR electrostatic tweeters—Philips midranges See original listing
Item Sold
Item condition:
--not specified
Nov 07, 2011 20:57:50 PST
US $750.00
$130.00 Standard Shipping | See details
Item location:
Lake County, IL, United States


eBay item number:
Seller assumes all responsibility for this listing.
Last updated on  Nov 06, 2011 11:52:55 PST  View all revisions

Item specifics




Floor Standing

Offered for your consideration is a remarkably well-preserved pair of Infinity 2000A loudspeakers, manufactured in 1973. They feature a three-way design with Eminence 12” Alnico magnet woofers, 4” Philips midranges, and an array of four RTR electrostatic tweeters per enclosure! The drivers are housed in attractive cabinets covered in nicely-figured, dark honey-colored real walnut veneer. Fairly sizeable at 26” x 18” x 12”, the cabinets' proportions are well-balanced and blend effortlessly with just about any décor.

Infinity Systems, Inc. was started in 1968 by Arnie Nudell and John Ulrick to showcase their revolutionary Servo Statik I system. The SS I used RTR electrostatic arrays for both mid and high frequencies, with a servo-controlled, amplified 18” woofer in a separate enclosure. The talented founders created an incredible speaker system, but it cost more than some new cars in 1969!

Infinity had three speakers in the very beginning and the 2000A was their second model after the legendary SS I. It delivered outstanding music reproduction, yet was marketed at a price level more people could afford, and outlined many design principles for their later Quantum Series. The 2000A was offered from 1970-73 and only several thousand pairs were built.

Excerpts from an article by preeminent audio journalist Julian Hirsch that appeared in Stereo Review, November 1971

To open the Infinity 2000A product brochure in an Adobe .pdf, please click here.

Many thanks to Analog Alley, an outstanding source for thousands of hard-to-find audio and video manuals, for the brochure scan.

These Infinity 2000A's are in clean, near excellent condition. They’re late production models, a matched pair with consecutive serial numbers. I bought them locally several years ago from the original owner, a retired engineer that had lots of quality gear to rotate—these speakers had been very well cared-for. Nevertheless, the walnut veneer had gotten a bit dull and dry over the years. So, I gave the cabinets several light wipings with Formby’s low gloss Tung Oil to rejuvenate and protect the veneer. There are a number of tiny nicks, scuffs, and shallow scratches—mainly on the bottoms—but the Tung Oil blended them in nicely as well. The walnut, with its figured grain pattern nourished once again, looks wonderful.

Plus, both front and rear grille panels are in great shape with no structural imperfections to the frames or fabric, and the fronts hold tightly with Velcro at the baffles' corners. And, both “early-style logo” metal Infinity emblems are present and in good shape, though one has a few tiny paint chips. All-in-all, they’re very well-preserved speakers from Infinity’s earliest product line.

The 2000A’s are a three-way design using 12” woofers with large Alnico magnets. Per the EIA source/date code on the thick field cover, “67 7249”, these woofers were made by Eminence (67) in the 49th week of 1972. The damping clay around the voice coil dust cap was specified by Infinity, perhaps added by them, to increase bass response. As a result, this restricted the woofers’ higher frequency output, which they wanted since the midrange driver would be taking over at a relatively low 300Hz. Almost every pair of 2000A I’ve seen online, which isn’t too many since they're pretty rare today, had the cone damping. And, aside from the damping clay, these appear to be the same Eminence Alnico woofers used in the late 1960's Klipsch Heresy. Structurally, the woofers are in perfect condition with sturdy paper cones and permanent accordion-style surrounds. There’s a bit of discoloration at the edge of this one cone, but that’s about it.

For midrange duty, Infinity chose the venerable octagon-flange AD 5060/M8 from Philips, the Dutch electronics giant. Philips made very high quality drivers in the 1950’s-80’s for their own speakers, and also for respected companies such as Infinity, HH Scott, Rectilinear, Bang & Olufsen and many others. The AD 5060/M8 is a superb full-range driver, complete with whizzer cone and heavy ceramic magnet structure. It’s capable of approaching many tweeters in the upper frequencies, but Infinity limited its range from 300Hz-1800Hz through the 2000A’s crossover network. The Philips drivers’ textured paper cones, whizzers, and permanent impregnated textile surrounds are all in flawless shape. And, since the midrange rests in a separate chamber from the stalwart woofer, no isolation 'canister' was needed behind the basket.

Infinity designed the 2000A as a complete “system” around the array of four RTR model HF50 electrostatic tweeters per cabinet, the same high frequency drivers they used in their Servo Statik I. The tweeters are also housed in their own chamber, which is open at the front and back of the cabinet for balanced radiation of the high frequencies. RTR made the HF50 (and variants) based on units from Janszen, the early leader in electrostatic technology, and they were rated to a then unheard-of 30KHz. These superlative tweeters, used in a number of exotic early 1970's speakers, have a cult following amongst many advanced hobbyists today (as of this writing, new old stock RTR electrostatics are available on eBay). I didn’t want to disconnect the tweeter wiring, but a rear grille panel came off easily so I took front and back photos of the whole array for your review.

The terminal plates are connected to sophisticated crossover networks and employ attenuators for the mid and high frequency drivers. The electrostatics can be left in the “normal” position, increased by 3db, or set to “protect”. The latter feature added an extra inline resistor to be used if they were connected to an underpowered receiver/amp susceptible to ‘clipping’ at high volume (something a person buying these speakers was not likely to own). For midrange, the attenuator is a pretty straightforward 0-10 dial controlling output based on listener preference. And, the +/- terminals have sturdy binding posts instead of the tedious slot-head screws that most speakers used back then.

Most importantly, the Infinity 2000A sound brilliant. They’re strong, clear, and detailed with no noted sonic issues and have never been overdriven while in my possession. Over the years, I’ve used them with a number of quality amps and receivers that deliver clean, stable power; most recently my McIntosh MA-6100 and stout Pioneer SX-950. The Infinity brochure suggests they be used with amplifiers delivering a minimum of 35W per channel and both of the period reviews I read stated 125W of max input power (evidently gleaned from an Infinity spokesman).

The damped 12” woofers, coupled with ported cabinets, produce smooth, deep bass with the special warmth of tone that makes Alnico magnet speakers still so desirable today. Infinity could have sourced the woofers from a number of companies—CTS, UTAH, ROLA, and Jensen to name a few—and even saved money by specifying potent but cheaper ceramic ferrite magnets. Instead they chose Eminence, a young company in 1970 (just like Infinity was), and their heavy Alnico magnet bass model. The engineers wanted solid low frequency response, with just the right tone, but at a price level that precluded using costly, cast-basket woofers like the early Cerwin-Vega unit in their SS I. Today, Eminence is the largest domestic raw speaker builder.

In the critical lower midrange frequencies, those Philips drivers provide very smooth, fast response. They’re the same midranges Infinity used in their revered 1976 Quantum Series, with some M8’s serving as “midbass couplers” to mid domes and others being the AD 5060/sq8 midrange squawkers with integral canisters. They’re an exceptional vintage driver.

Lastly, all eight RTR HF50 electrostatic tweeters are working properly and have a clear, transparent sound with the upper-frequency ‘sparkle’ you’d expect from drivers rated to 30KHz. I’ve owned lots of speakers over the years and these are some of the brightest, least fatiguing high frequency drivers I’ve ever heard. They sound just as good to me as Infinity’s later permanent magnet EMIT tweeters, even the top versions rated to 40K+ cycles.

The electrostatic tweeters are powered by transformers adjacent to the crossover networks—that’s how the tweeter diaphragms are “energized” for play. The general consensus in the online audio forums is to leave them plugged-in, unless you aren’t going to use them for an extended period, since they draw very little electricity (22 volts max input per an RTR data sheet I came across). The forum audiophiles also suggest letting the transformers warm up for a few hours, if they’ve been unplugged for a while, before treating them to an amplifier signal. I never knew that before, and they always played perfectly, but it sounds like good advice to follow.

And, though the speakers are rated at a "nominal" 4 ohms, they’re really more in the high 6 ohm range. From what I’ve read, the 2000A impedance curve can momentarily dip to just under 4Ω at its lowest point, unlike many "true" 4 ohm speakers that can fall below 2Ω and strain all but the heartiest amps. I tested the woofers' DC resistance at a perfectly-matched 7.3Ω, and the midranges at 6.3 and 6.7Ω, respectively, right in line with a nominal 8 ohm driver rating which should tell you something. Nevertheless, Infinity played it safe by rating them conservatively.

The Infinity 2000A’s sound absolutely wonderful and are a very important speaker from Infinity’s early days—the forebear to many of their later high-grade models. They’re not frequently offered for sale—I've yet to see another pair on eBay—and seldom if ever in condition this nice. As pictured and described, this splendid pair of Infinity 2000A speakers is offered at a competitive price. In return for this sizeable investment, the new owner will cherish their rarity, remarkable sound quality, and beautiful appearance for many years to come!

Terms of Sale:

Important: I encourage prospective buyers to e-mail any questions (via the “ask a question” tab) they may have about these Infinity 2000A speakers since there are no returns, refunds, or claims considered for this listing. I pack items very securely, and full insurance coverage will be included in the shipping cost, but will not be held liable for negligent handling in the shipping process nor fall prey to a “parts switching” scheme of any sort. In addition, these are very high quality speakers but they’re also almost 40 years old. There is an inherent risk to buying vintage electronics, even from the most respected companies, as some parts can suddenly fail. Moreover, I have no way of knowing in what manner these speakers will be used, the condition of the equipment they'll be connected to, or what level of audio experience the new owner has. I don’t foresee any problems, but nevertheless had to state the above. If this makes you skeptical, please take a look at my feedback pages and you won’t be. I’ve been an eBay member for over 12 years and have served hundreds of satisfied audio customers. And, I’d like you to be the next one!

A note on shipping: At over 45 pounds each without boxes/packing materials, and having a sizeable footprint, it’ll take me several days to devise/implement a packaging plan to get these speakers to the new owner safely. Two separate sturdy boxes, lined with dense Styrofoam panels (and other protective materials as I deem fit), will be used to ensure no disappointments upon arrival. Naturally, the quoted shipping cost is for both speakers.

Local pick-up is fine, actually preferred, for those in the Chicago-Milwaukee metro area (or farther, if you’re willing to make the drive). We’re located about 35 miles north of downtown and some 20 miles south of the WI State line at Kenosha. For those interested in pickup, please contact me so that I can discuss that option with you. And, for a cash payment at pickup, I’ll offer a 5% discount on the purchase price for sparing me the time that's necessary to pack these correctly.

Otherwise, payment is due at checkout by PayPal. U.S. lower 48 mailing addresses will pay $130.00 ($65.00 per box), while members living west of Denver will be invoiced for an additional $40.00, for shipping via FedEx with tracking, signature confirmation at delivery, and full insurance coverage included. Members with shipping addresses in AK, HI, PR, US Territories, and Military APO must e-mail for a shipping quote before proceeding as the charges may be substantially higher.

International purchases are not accepted for this listing—the boxes will simply be far too large and heavy. Canadian members that have a “handling agent” on the U.S. side of the border are welcome to contact me for permission to purchase. In such a U.S./Canada handling scenario, the U.S. agent’s address will have to be your confirmed PayPal address (however you choose to sort that out with PayPal), and you’ll be responsible for driving into the U.S. for pickup at your agent and any applicable Customs fees upon re-entering Canada.

Thanks for looking, and I look forward to doing business with one of you!

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