Just Purchased Infinity RS2B / RSIIb owned RS 2.5

FYI Infinity Fans:
I have lusted after some RS2bs for 20 years after loveing my 2.5s. I thought the 2bs would fill in the middle and keep all of the strengths of the 2.5s. In reading the manual, I was unaware that the 2bs had a bass equilizer (not crossover) that was NOT optional. The bass equilizer has been lost. I hooked up my VTL compact 100s with several preamps & the sound was mud in the bass and boring in the emims/emits. One of the emits is even covered 50 percent, the top one in the front. These 2bs sound like monster cable . . . go figure. Monster cable was used in the speakers. Also, it turns out that ONLY the middle emim is hooked to the midrange control. The middle emim is the only one that sounds like the emims in the 2.5...they are running full out. The top and bottom emim are subdued and they are trying to mimic a good dome midrange....yes the lower vocals are better but who cares?? I have lost the magic of the emims. I have had some Infinity Sigmas in my room and one super emim did a better job than these three emims. Last night I hooked up a couple of transitor amps and the sound was MUCH improved... remember what older monster cable did to good solid state stuff? in the 80s. I guess I'm going to stay with threshold but I own several good tube amps that I love to hear the imaging etc etc. I might be nuts but the improvement I have gained with Kimber Kable 4TC and Audioquest jaguar interconects is lost in the old monster cable wire?? I am probably being to hard on these speakers, but I remember a german saying the 4.5s were the best of that vintage. How are the emims controled in the RS1bs?? are they all hooked to the crossover controls?? To be continued. Thanks for reading. Larry
I had both an RS 4.5 and later on a 2b (which I bought from someone who worked at the factory) I can't recall if I had a bass equalizer box, but I was biamping anyway, so maybe I didn't need one ;-) Otherwise you may need it along with the jumper cables. Assuming all the drivers are OK, it could be that the connectors (which were push-on IIRC) to ALL drivers including woofers need to be cleaned with DeOxit or similar. Ditto the level controls which you can get at from inside after removing the woofers.

To get the most out of the 2b's (and the 4.5's too as a matter of fact) biamping is almost mandatory, with tubes on top and solid state for the woofs.

Check out this site http://www.infinity-forum.de/rs_iia.html crossover schematics are here http://www.infinity-forum.de/download/RS_IIA_technical_sheet.pdf

They might be able to provide you with a schematic for the equalizer. BTW, don't sweat the Monster Cable, at those (short) length, it really won't matter what they use as long as it's heavy enough for the power. It's the connectors and rheostats that you should check.
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Elizabeth, did you check out the URL's I provided? They show the internal and external x-over circuits including component values and the driver hookup diagrams. Should be a snap to build the equalizer box if one wanted to. However, using a good active x-over (like a Bryston 10B) either in mono mode or for biamping should do the trick. I'm not convinced the internal x-over caps are bad, but I suppose it wouldn't hurt to replace them with better sounding ($$$) ones ;-) A better bang for the buck I think would be to change out all those cheap inductors Infinity used, for really good coils.
Thanks guys for your input. I have been reading the owner's manual and it states two times that the bass equilizer in cap letters MUST BE USED whether in single amp or bi-amp mode on pages 5 and 18 of owners manual. The manual suggests if you hear boomy bass reduce the bass control (<100hz) and the contour (<1khz) of the bass eq. I have my tech looking at the schematic and he said two of the transitors are given a Infinity number that does not cross to anything???? also, the schematic says to connect to mosfets?? Over the last few days I have run single amps, tube and transitor with all sorts of biamping variations....vtl 100s, vtl 75/75, ARC d-70MKII, dynaco 416, threshold 200, and two hafler xl280s in mono and stereo mode.. The best sound . . . one single hafler xl280????? I'm going to keep experimenting but I do not hear the ribbon sound that I am used to from the top and bottom emims. Elizabeth, I am hearing much lower frequencies from these two not lower output...the middle one sounds like my two emims in the 2.5s. I will clean the rheostats and connecters. BTW these speakers look like they just came from the factory. I think they may have been in storage??? absolutely no dust or discoloration anywhere. Oh preamps ARC SP8 and Quicksilver full function and VTL deluxe. Thanks again guys. audio buddies
I owned the 4.5's/RS-1b's/and then the Betas.

My friend still has a mega modded pair of 1b's.The crossover mod is a MUST!!Rear cabinet damping does not hurt either.

I did have a friend who had the II B's.I loved that speaker,and it is "well" worth taking it to the max,if you can.A superb speaker!
I felt the 4.5 was outpointed by the 1B's/and Betas.The II B's are more coherent too(than the 4.5),but a touch less powerful,since it has smaller(faster though) woofers.It really is a killer speaker,especially if in "as new" condition.A Classic!!
I remember my experiences quite well,as I think the Infinity speakers of that era hold up very well....Especially if you try to mod the crossover,and attend to some other tweakery.

BTW,there is a Guy named Bill Legaulle(spelling?) who lives in NY state(from the article I read about him awhile ago).He is an "expert" on anything Infinity,and has built up quite a following regarding re-voicing Infinity speakers,from that era.He actually rebuilds the Emim/Emit drivers,and sets them up as matched pairs for each tower.I know he has many Infinity followers,who have had him rework their speakers.He matches drivers to .5 db tolerances,per tower position. I have no doubt the guy is a "master" with Infinity/Emim/Emit stuff....Worth seeking out,if possible,but I have no more info about his whereabouts.
I DO believe I read about him in Positive Feedback,or one of the web mags.Also,one of my friend's "used" to know him well,and confirms his abilities.

Best of luck
I wish I'd never sold my 2B's!! You're right Speedy, I could never get those damn 4.5's to image!(and they had plenty of breathing room too!)
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After listening to the two emims in the 2.5s for 20 years, it is taking time to adapt to the two outer emims playing lower frequency but I am getting use to it. Much better on piano and vocals. The low end is my big problem. If I play at lower volumes the bass is the best I have ever heard, but when I turn it up it definitly gets boomy in my room with the built in shelves and cabnets next to the fireplace...The speakers are half in front of tile on fireplace and half in front of cabnets..two feet away. I opened the cabnets up to put up some stereo stuff in and went back to listen before shutting the doors.....Big difference in bass, total boomy mudd. I am going to take the speakers to a friends house with a solid wall behind them. I think infinity knew the speakers could get boomy and thats why they made the comments in the manual. OK I HAVE A BIG QUESTION. Can anyone tell from the circuit diagram of the bass eq if in the 12 o'clock position it is neutral and not affecting the lower frequencies??? Thanks Larry.
I sent him an email and Bill answered at 5:30 am!!!!
FYI Bill Watkins did the refoaming.

Dear Larry,

The manual is correct of course. If they're very boomy, it could mean that they were incorrectly refoamed, using the incorrect-tension material. The other reason would be too much cabinet stuffing, or damping added to the cabinet walls. The EQ was made by the good people at Monolithic Sound in CA. It's possible that they may still have an EQ available, though I doubt it. There's a company called DB Systems (location unknown) that can make custom EQ/crossovers. You may want to Google them.

The 2b's are one of the most musical of all Infiniti's, and one of my favorites.

Enjoy the weekend!

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.
I've had 4.5's and RS11b. The RSllb is far superior. The higher and lower mids are wired to limit high frequency, so vertical dispersion is not beaming. The middle EMIM goes up to a higher frequency. The 4.5 loses focus if you are not at exact center of the midrange. The RSllb does not have that problem.

If you really want the RSllb to be a world class speaker, disconnect the two 10" woofers. Get a 36"h x 24"w 3/4" wood panel and mount an open baffle 15" Eminence Alpha 15 woofer. You'll need an electronic crossover. This will provide a seemless open and box free natural sound to match the EMIMs and Emits. Of course you'll need to biamp. One more thing, the open baffle woofers will only go down to about 50 hz, so add a good sub for the bottom octave. I use a HSU 15"
Ladycharnet, the EQ box does more than boost below 100Hz. I have studied mine extensively and also modded it extensively, and here are the facts:

1) bass gain adjusts bass boost below 100Hz, especially from 50Hz down
2) contour adjusts the slope downward below 2000Hz

Without both of those adjustments the RSIIbs will not be flat in response. The non-EQed speaker has a rising response below 2kHz that peaks at 50Hz and then falls like a rock - the contour adjustment knocks down the rise and the bass gain fills in the area below 50Hz.

Here is my in-room frequency response without the EQ:


and here it is with the EQ:

RSIIb with EQ

Here is a plot of the frequency response of the EQ unit itself when fed a pink noise signal from 20-20kHz:

EQ Response

If you have another EQ unit that allows you to plot the in-room response you may be able to come up with settings that approximate the stock unit.
Marchand Electronics has been around as long as I can remember (we're talkin' half a century!) and it wouldn't surprise me to learn that Infinity "borrowed" their equalizer from this unit, although in a "watered-down" version. Come to think of it, Marchand produces many, many OEM components, and quite possibly made the bass EQ unit for Infinity! Look here:
And check out their other stuff -- they're a rock solid, straight up, Amerikan company!! Y'know what I'm talkin' about?!
Well I un-watered-down my unit (I guess that would be "concentrating" it). Mine now has all metal foil and metal film resistors, high speed OPA827 opamps, and high quality PP, PS and copper foil/PIO caps. I also moved the power supply and the output circuits off the main EQ board to reduce interference, upgraded the capacitor filter to a CRC, added Bybee Music Rails DC power conditioners to both the + and - power supplies, inserted a TI-shield shield between the noisy power supply section and the rest of the unit, and built a directly DC-coupled output curcuit using very low DC-offset opamps to replace the stock MOSFETs. I also replaced a couple of the resistors with cermet pots so that I could tailor the response curves to be different for each channel to suit my room.

Here's what the inside of the unit looks like now:

Modified LF EQ Unit
Guys, thank you for your thoughts and input. Muzakk, I couldn't agree more that the higher and lower mids are wired to limit high frequency on the RSIIBs. I guess I got addicted to the beaming midrange of the 2.5s. I thought it was detail. To me this affect dulls the sound with my expensive tube amps and I find myself hooking up a transistor amp to offset this sound. I wonder if Infinity was using Threshold when they were working on these speakers. It seems to be a good match, but I loose the "openness" of a good tube amp. Also, the 10 inch woofers have a hooded sound to me. I miss the watkins 12 inch sound of the 2.5s and 4.5s. I know they were trying to fill in the middle with the RSIIs, but I lost the magic of the older speakers (upper midrange) . Also, I agree the bass EQ is doing alot to alter the frequency response and I am currently using the EQ for the RSIIa which is a much less complicated circuit than the EQ for the RSIIb. It is possible the EQ for the RSIIb is not working as it should. I am still amazed at people that do not realize what the EQ box is doing?? Thanks again. Larry

PS for my fun back-up speaker system I put some 12 inch polypropelene (20-400HZ) infinity car subwoofers in some Dahlquist DQ10s and then I added a Heil midrange/tweeter driver to replace the dome and piezo tweeters....sorry I understand it sounds crazy but I love the sound of these speakers with tube equipment.
Update Feb 2014:
I moved to a different house and put the RSIIbs on the tile floor versus sitting 12 inches up on on a large fireplace hearth at the old house. WOW!!! what a difference 12 inches makes....now I am sitting on the couch staring at the middle EMIM on the RSIIB and the midrange and highs are to die for.... no more "hooded" sound from vocals out of 10 woofer and lower EMIM. At the old house when I was sitting, ear level was between the top woofer and lower EMIM. The 2.5s sound very similar at either location....two beaming EMIMs ??? I am having fun listening to the IIbs...like this is the first time I have given them a chance...love playing with different amps and tube types. Larry
If you really want to go crazy, check out the new EMIM ribbons offered by Apogee Acoustics. They fit in the standard EMIM shell and are a HUGE upgrade in sound quality over the originals.

Graz at Apogee makes them in batches of 90, about once or twice per year. You have to get on the list and when he has enough pre-orders he makes a batch. The build quality is stellar. Here's a link to his Infinity forum:

New EMIM Ribbons

I sold all my ribbon speakers out of my RS2B and what I had left from the past. If anyone wants the RS2A/B bass contour, I have it packed and will sell it. I also have a JBL 553, which I prefer. No more bi-amp and tri-amp for me, so I am going to sell the JBL and I believe I have the manual? The JBL was made foe use with the JBL horn midrange driver, but it s a descent quality unit and uses only XLR. It is not as good as FM Acoustics, or Accuphase, yet it is a decent electronic crossover.
Seeing as how this post is almost four years old, I don't presume you still have the bass contour unit?