Reference Standard II B
and II A


Low Frequency Equalizer

Introduced: 1981
Dimensions (II A / B): 140 x 58 x 28 cm
Weight (system): 90 kg
Bass: 2 x 25 cm
Mids: 3 x EMIM
Highs: 3 x EMIT (one on the back)
Suggested for amplifiers with (II B): 75-300 Watts per channel
Frequency range (II B): 25 Hz - 32 kHz
Crossover frequencies (II B): 150 Hz, 800 Hz, 4000 Hz, 8000 Hz
Special: equalizer for bass drivers
Suggested price (system): $2700.00

The owners manual and technical sheet can be downloaded here:
Infinity IIB Owners manual.

I'm not really sure what the difference in the II A and II B's are.
I have a pair of the II B's.
If anyone has a brochure please email me a scan if you will.

Shred's Review - December 2007
I've had these speakers for a few years but I have never put them to their proper use.
The first problem was that the foam on the woofers were rotting. I also did not have the Low Frequency equalizer, or the power supply for it.

I eventually found the LF unit, a power supply, and had Bill Watkins of Watkins Engineering  re-foam the woofers for me.

I decided to really try these out in my bedroom. Previously I had a pair of great sounding Polk SDA2's in that room with a pair of smaller Infinity RSB's on top of them to bring out the high end with their EMIT tweeters.

I've had the Polk's for a long time and they have always sounded good to me so I was a bit reluctant to change them out. But since Mr. Watkins re did my woofers I felt an obligation to really try them out.

The speakers are rated at 75-300 watts per channel in the manual but I thought I would try them out with my old workhorse a Sansui AU-919 Integrated Amp of 100 watts per side.
This amp is a beast, it must weight about 60 pounds or more. The transformers and capacitors are HUGE in this monster.

After taking some time to figure out how to set up the LF Eq I finally got it all running smoothly. My brother in law and I wanted to really hear what these babies could do so I got the the original, un-remastered Dire Straits - Brothers in Arms CD out and played "Your Latest Trick", and "Ride Across The River" at a nice loud volume.

Man, were we impressed!!! 

There was the crystal clear high end and mids due to the EMIT and EMIN drivers. 
They blended in perfectly and seamlessly with the 2 ten inch poly woofers on either side.

The bass was very full, very deep, and most of all very tight sounding.
They really blew away the Polk's I had been using, the difference was very marked.
The imaging was astounding and the depth of sound extended well beyond the physical front of the speakers, I suppose because of the rear firing mids and tweeters.

We cranked the speakers up waiting for a crescendo in the music and I was a little fearful of hearing some distortion or possibly even blowing a speaker fuse or even a tweeter.

But to our amazement none of that happened.  The 100 watts of pure Sansui power was enough the really give these speakers a nice volume and not sound distorted in the least.

I can honestly say this is the finest pair of speakers I have ever heard of this size.

They DON'T need a subwoofer because the bass is so deep, full, and clean, and I'm sure adding one would only muddy up the sound.  That tight bass MUST come from the sealed box, acoustic suspension design.  Every speaker that I listen to that has an sealed box design has a much tighter well defined bass than a bass reflex or ported design.

Yes, it's common for most speakers today to use ported designs, and you will get a lot more efficiency as far as needing less watts to power the speaker to get a loud sound out of it, but in my opinion the bass will suffer. 

That's not to say there aren't any good ported or passive radiator designs out there. 
My Polk SDA's that I replaced these with had a passive radiator and sounded good and clean. But the bass was never as tight as these speakers have,

I really don't feel the need to add surround sound because they have a surrounding feeling with the rear firing drivers.

But then again I always have my InfiniTesimal's if I want to add them to the system.

Putting the speakers to some longer period listening tests I listened to the remastered version of "Return To Forever's - Romantic Warrior".  This is a very demanding piece of music with a lot of dynamic range. 

Chick Corea's mix acoustic piano and synthesizers, Al Di Meola's acoustic and electric guitars and especially Stanley Clarke's Ambelic, piccolo, and acoustic bass sounds are hard for any speaker to reproduce at a higher volume.

The title cut, "The Romantic Warrior" sounded very good with it's extreme dynamic range and Stanley Clarke's acoustic and electric bass playing along with Chick's dramatic piano work.

Again I felt the speakers did an amazing job at handling this complex electric/acoustic fusion music.  I drove the volume to a high level, turning it up little by little and most of the time the sound seemed as flawless as any remastered 30 year old piece of music could sound.
I did start to hear a little crunch in the higher frequencies but only at very loud volumes.

After pushing the speakers as hard as I thought the Sansui amp would go I went over for the "heat test" and indeed the amplifier was quite warm to the touch.  It never flipped it's protection breaker, something I have done on it before, but I did feel that the amp was being pushed to it's limits.  I really don't need more power for these speakers but I'm going to experiment just for the heck of it.

I have another old 85 RMS watt Sansui AU-710 integrated amp that I will be using to to power the high frequency drivers. To use both amps I'll switch them to the slave amp mode, bypassing the preamps in each and using a NAD 1600 Monitor Series Pre Amp to control them.

I've got some questions to think about in this ongoing review while I try out different configurations of equipment.

I wonder if I will really notice the difference by adding the second 85 watt Sansui amp, or if because it is of a lower power it, may not sound much better at all.

For now I can only ponder that as I have to make some more Monster Cables to hook up the bi amp configuration.  The speakers use pain in the butt banana terminals to connect with so I'll have to solder a new set of plugs onto some Monster Cables.

So look for some additions to this review as I get the additional equipment hooked up.

I really want to supply these speakers with more power before I hit them with the 

Quadratic Equation of Progressive Rock Music

That being Emerson, Lake and Palmer, Yes, Genesis, and of course, Pink Floyd.  I'll be auditioning these very demanding sonic delights soon, and quite a few others thrown in for good measure.  Stay Tuned!

Review Update - January 2008

I did some more listening with just my Sansui AU919 amp hooked up and I was very impressed with every type of music I listened to.  But after about an hour of high volume sonic bliss the protection breaker would flip on the amplifier, and the top of it got VERY hot. 

So instead of adding a second, lowered powered Sansui amp I decided to hook up my 
NAD 2400 amp to the speakers that delivers about 150 watts RMS per side at very low loads down to 2 ohms or less.  I've used this amp for years and it is very clean sounding and very stable.  It is the same amp that earned the THX logo from Lucas Films for delivering an extraordinary amount of power. I have a matching NAD pre amp to control it.

I did notice a slight improvement in the clarity of the sound especially at the higher volumes.
The breaker never flipped on the amp, but it also got very hot at about 115 degrees.

There was so much woofer movement I thought that the cones would actually pop off their bobbins, so I didn't want to push the speakers any harder. Even at that level the clarity of the speakers was amazing.

What I've decided to do was to buy a second identical NAD amp and bridge them and have one per side.  From what I understand that makes these amps very powerful delivering close to 325 watts of RMS power at very low impedance's.  The owners manual states that at 4 ohms the amp delivers close to 900 watts of peak handling power.

I've since tried out the 2 amp configuration and it really opened up the sound, and the amps don't get as hot as the single one did. The sound is clearer and excellent.
A lot of clean power is what these speakes need.

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