Just Purchased Infinity RS2B / RSIIb owned RS 2.5

FYI, Believe it or not I was able to find a rs2b low frequency EQ through audiogon. Someone had sold the speaker parts and still had the equilizer. My technician said the mosfets used in the lf equilizer affected both the top end and low end. The mosfets used in the equilizer are called "Channel Enhancment Vertical Power Mosfets" and have not been made in years. With the lf equilizer the speakers sound MUCH! faster. Bass is fantastic no matter what amp I use, tube or transistor and the emims sound much better. I firmly believe the speakers were desingned to have the lf equilizer in line....JUST LIKE THE MANUAL SAYS. http://www.datasheetarchive.com/pdf/3631983.pdf

So my wife and I are bringing in the groceries the other day at our condo when a neighbor comes up and asks, "Do you know anyone who's into really big, old..." so I'm thinking, "Say speakers, say speakers." And my wife is thinking, "Say anything but speakers." And he says, "...SPEAKERS." So of course, I'm like, "Yup, I'm your man." The wife instantly shoots me the death stare.
He takes me to his garage (which he's obviously cleaning out) where he has a pair of these Infinity RS-2B's. I'm not sure what they are right away, but I know they look exceptional, despite the cabinets not being in the greatest shape -- with some ugly water seepage on the bottom of one and some dings in the wood here and there on both. But the woofers and surrounds look tight, the midrange drivers and tweeters are most intriguing, and he has this EQ unit, which he insist is required.
Anyway, these things are destined for the basement, as I already fought hard enough to get the Maggie's in the living room, nevermind trying to get these into the bedroom. So I've got a section of the basement carved out with two layers of insulation and sound absorbing foam on the ceiling, and a thin, industrial carpet on the concrete floor (for home recording purposes).
I get them set up down there and run them through a heavily modded Dynaco PAS-3 (with nice Telefunken 12AX7's) into the Infinity EQ and then a Carver Pro ZR1600, which puts out a more-than-ample 600 watts per side at the rated 4 ohms (off the top of my head, but I'm sure it's up to the job, since the manual I downloaded says they only need between 75 and 400 watts).
Well, they sound AMAZING, but my question is this: Are these the single least efficient speakers ever made? To really make these things sing, I have to turn the Dynaco preamp volume up past its famous 'sweet spot' at around 12:30 to get them to open up. They can take everything the amp gives them, and it sounds very good at the lower volumes. But is the heavy damping on the ceiling having that much of an effect, or are these speakers just that power hungry?
BTW, I was running a pair of Dynaco A25's through the same preamp and two Dynaco Stereo 70's in mono bridged mode in that exact same space before, and they didn't require any extra juice. Granted, the A25's are much more efficient (I think). I think the Infinities are rated at 87 db, and I would have to guess that the A25's are around 91 (without the power handling, obviously).
Either way, I'm very pleased to have stepped into such stellar sounding speakers for FREE. Thoughts???

I have a had a pair of RS-2B's for over fifteen years and I do not anticipate their replacement as they sound as good as anything else I have heard costing less than $15K.

I think your level problems are related to amplifier sensitivity and not speaker efficiency. You said the Carver was a "Pro ZR1600". While I am not familiar with Carver's current products, the fact that it is labeled as a pro amp means the the sensitivity is likely to be lower than a consumer amp. Pro gear operates at a level that is 14 db "hotter" than consumer gear (+4 dbV versus -10 DBV). That means that the PAS 3 will have to be turned up 14 decibels in order to compensate.

Since the RS-2B's allow passive bi-amping, please allow me to suggest that you try hooking the Carver amp to the EQ output and use it to drive the woofers. Then hook up your Dynaco Stereo 70's (use the 16 ohm taps - they sound the best) to the input parallel jacks on the EQ unit and use them to drive the midrange/tweeter arrays. You will get the best of both worlds - solid state power and control for the bass and the delicacy of tubes for the rest of the spectrum.

May I also suggest that you take an hour of your time and replace the sheet metal screws that hold the woofers to the cabinet with # 10X32 tee nuts and machine screws? It's well worth the effort as it will clean up the bass to an amazing degree. While you are at it, you should tighten the screws that hold in all of the other drivers. I find I have to do this every six months or so to keep these wonderful speakers sounding their best.

Well guys I feel like an idiot. I have listened to these "boring neutral" speakers compaired to my Infinity 2.5s for well over a year. . . . . and the other day I decided to look at the fuses. All 4 fuses for the emims and emits were sagging in the glass and they were tarnished and corroded. The wire was soooo thin....being only 1 1/4 amp fast blow fuses. Well anyway I replaced the fuses and WHAZAMM!! CRYSTAL CLEAR DEEP BEAUTIFUL SOUND. I think the fuses were original...25+ years old??? When I first set up the speakers I put my ear up to all the drivers and they all worked....so I thought the fuses were ok. I have thousands of dollars worth of preamps, amps and interconnect and all of the sound is going through a hair width wire. Sorry for the confusion above. Larry

The RSIIA/B does come with a bass contour box. The manual states the high pass does nothing and if you have two preamplifier outputs, you can go direct to your midrange and high frequency amplifier. What the bass box does is allow you to adjust the overall volume and it has an adjustment at about 100HZ. I use balanced connections; any device where one is able to adjust the gain will work, even a gain on the amplifier. For a better set-up, a bass contour with gain and eq setting control will do the same as the box.