Infinity IRS Sigma


Hello everyone,

Anybody have first-hand experience with these speakers? I am thinking about adding these to my 2nd 2-channel system...

I have the JBL L-300 Summit's in the first system.

I plan to power them with 2 McIntosh MC-352.

Thanks in advance!!!
ledcolo
As far as vertical biamping vs dual bridged monoblock, depends on the bias of the amps and impedance of speakers. Class A amps, in order to stay in class A, should drive above 4 ohms and bridging only increases A/B power, albeit by a factor of 4 (for most SS). Essentially, bridging is a lot like cutting the impedance of the speakers by half. If the speakers are already low impedance, they can be a difficult load. The upside of bridging is sheer power, the ability to use shorter speaker cables and monoblock separation (as rumoured). The upside of vertical biamping is easier loading and something called transconductance, which is the reactance of the woofers/x-overs across the entire bandwidth. Which is better for you is up to experimentation. The Macs are a sturdy design but the IRS line is notoroius for being tough to drive. When the Kappa 9's were released, many highly regarded amps of their day got their smoke let out.

Infinity was tight-lipped even before Harmon bought them and very little specific info was published. The Infinity Classics website closed down, unfortunately.
Ngjockey & Steelhead,

Thank you for all your feedbacks...

Just as an update, I brought the Sigma's home and hooked them to the MC-352's...

Wow!!! What a sound stage and presence!!! They sure do love the power, though...

Still need to fine-tune their placement for the best sound stage and balance...

Also, haven't decided to bi-amp them with two amplifiers in stereo mode or set each amp to mono and use them as monoblocks for each speaker!

Any suggestions or comments?

Also, anynone know anywhere I can get an owner's manual? Infinity/Harman is really no help!!!

Thanks and happy listening!!!
Hell, I'll chime in. First I had 4 JBL L200's for years in a rock and roll four channel setup (Wish to God I still had a pair).

I was in the old audio kaserne one day and thought a sax player was in the damn listening room. What was that!!! Infinity 4.5's. Ruined me. I bought a pair. In 1991-2 or thereabouts I had them sold for essentially the same price I paid for them. I couldn't bear to part with them and after listening to top drawer KEF and B&W decided to keep them. I didn't replace them until I fell for Martin Logans in 99 or so. I gave the 4.5's to my brother.

Believe the Sigmas are better than 4.5's. You should love them. You will need power though. My 4.5's I biamped with two Hafler 500's and they could make them whimper. But deep bass, clean and fast and overall a wonderful speaker. There is a rabid Infinity site on Yahoo. Get ahold of those guys and they will set you up. You need to keep an eye on EMIT and EMIM repair or replacement as Infinity no longer repairs them. Infinity these days is not the same company since Mr. Nudell and Mr. Christie left.

Have a ball!!!
I think your second system will become your first. The Macs should drive them easily. People conditioned to soft domes usually think EMITs sound bright because they expect roll-off. Definately hi-end from the folks that started it.