Price Paid:  $5550.00 from Audio-T, Oxford

Summary:
I had a pair of PMC's excellent FB1s, but was looking to up-grade having moved my system into a much larger room in the house. I wanted more weight behind symphonic music and opera. Even though the FB1s dug very deep, they could not, with such comparatively small drivers, deliver the SPLs in my larger room.

I tried B&W 803s, ProAc Response 3.8s and the PMC IB1s. The B&Ws were a huge surprise and massive disappointment. Hyped the 9s here in the UK, they simply did not deliver the low-end information I wanted. I even returned the review pair to the dealer and badgered them into getting me a second set -- this time fully run in by B&W themselves -- because I just could not believe I was hearing all the designers intended. They too sounded very detached from the music and simply did not have the bottom-end authority.

The ProAcs were substantially better, but had a very humpy peak at about 50Hz that then sloped rapidly downhill. Close but no cigar.

The PMC IB1s were in a different league altogether. I drive them bi-amped and bi-wired with a pair of Meridian 557 power amplifiers. The only two difficulties I've experienced can be laid directly at their ability to resolve low-end information. Positioning is crucial if room nodes are not be over-excited -- I imagine the 7'4" ceiling in my room makes this more of a problem for me than it would be for many. The other issue only surfaced after I recently changed my DAC from a 24-bit Meridian box to a non-sampling AudioNote 3.1 Signature DAC.

The AN box feeds the chain so much more information that some of my CDs have become really irritating to listen to. Traffic noise, feet scraping, air conditioning whoosing -- you get the picture.

The fact is the PMCs faithfully reveal what's there, palatable or not. I guess that's why they're used in mastering suites!

Strengths:
Staggeringly revealing, immense and truthful bass, blissful mid-range.

Weaknesses:
Low-end in-room performance means they have to be carefully sited, and simply will not suit small rooms.

Similar Products Used:
PMC FB1.

Summary:
OVERALL (comparing the PMC AB-1 to the IB-1s)I was amazed at the difference between the two speakers. As good as I though the AB-1's were, they pale in comparison to the IB-1s. I have had several of my friends and family listed to the IB-1's and EVERYONE agreed that the IB-1s were a much better sounding speaker. (even my longtime girlfriend who will probably kill me the next time I upgrade any piece of my gear, admits to preferring the IB-1s)

PMC IB-1s DESCRIPTION
3 way Transmission line speaker system
(full details are available at: http://www.proaudio-web.com/archive/ib1s_e.html)

PMC IB-1s SPECIFICATIONS
Usable frequency response: 25Hz-25kHz
Peak SPL@1 metre: >116dB
Sensitivity: 89dB 1watt 1metre
Recommended Amp power: Up to 500watts
Effective line length: 2.4metres (8ft)
Crossover frequency: 380Hz & 3.8kHz
Impedance: 4 ohms nominal


LISTENING EQUIPMENT:
Bryston 4B-ST
Bryston BP-25
Athem CD-1
MIT Terminator 4 (HT4SV 12' Bi-wired)
Monster Cable M550i
Bryston Balanced Connectors
PMC IB-1s

SPECIFICS:
I'm not sure about this, but I believe that the sensitivity of the IB-1s are greater than the AB-1. They seem to play louder at the same volume level. As a result, listing to the IB-1s for an extended period of time is much easier on the ears (much less fatiguing).

2 HUGE DIFFERENCES:
The bass and the clarity of midrange of the IB-1s vs. the AB-1. The bass is very, very tight and controlled and almost scary in terms of being precise. This is probably the biggest difference between the two speakers. The AB-1's were not as controlled and could not produce the "hit" from a bass drum or the snap of drum tom. The AB-1's also tended to bottom out when the music got busy (ie: The Prodigy or any other heavy techno music).

Midrange clarity is also much improved. All voices (male and female) are much more clear and realistic sounding on the IB-1s.

I have a very unscientific method of judging speakers it's called the "shiver method". Certain passages in certain recordings can always send shivers down my back when I hear it, but only when it sounds realistic. The AB-1's only occasionally could give me these shivers. However the IB-1s tend to give me shivers on music that never has before. IB-1s shiver rating 10 out of 10. The AB-1 were a 3 out of 10.

The IB-1s are a HUGE improvement over the AB-1.