I have the opportunity to purchase a set of IRS III speakers. I cannot find a whole lot of info on the III’s, can anyone tell me what is the difference between the III’s and the V?
I will be the first to admit I am NOT the expert on classic Infinity names, but nothing shows up online when searching for “Infinity IRS 3” (or IIII)
If you look hard enough there is some info basically noting their existence, but not much else. They look exactly like Vs.
The V are 2 better of course 
I bet Paul knows and will add when he can.
(from ebay)
An Introduction to Infinity IRS
Infinity IRS legacy speakers are a known option when looking for high quality surround sound systems. When youre looking to turn your TV room into a home theater, surround sound speakers can really make a difference in quality. Here is an in-depth look at the IRS series legacy brand you will find on eBay.
What is an Infinity IRS speaker?
IRS is an acronym for Infinity Reference Standard. This name was given to a series of speakers introduced in 1980 by high-end speaker designer Infinity. The designers at Infinity had one goal in mind, to create a speaker system capable of reproducing the sound of a live concert as accurately as possible.
How many different models were part of the IRS series?
There were a total of four original speaker systems produced in the original IRS series. These were the IRS I, II, III, and V (there was no IRS IV). A subsequent line was developed alongside the original in the later years and sold at a slightly more affordable price point. This subset of the original bore the names IRS Beta, Gamma, Delta, Kappa, and Omega. Each system in the original series is listed below in chronological order.
- Infinity IRS (circa 1980): The prototype model featured a pair of woofer towers with six 12-inch polypropylene woofers, each driven by a 1500W amp.
- Infinity IRS II: This model contained a military grade accelerometer added to prevent damage at high volume.
- Infinity IRS III (circa 1987): This model didnt feature any significant change from the II.
- Infinity IRS V (circa 1988): Widely considered the pinnacle of the IRS model line, the IV featured new 2000W amp powered woofers.
Why does the IRS cost more than other speakers?
There are a few factors to consider when comparing the cost of Infinity IRS systems against the cost of other speaker systems of similar age. Some factors include:
- Artisan craftsmanship: The cabinets are hand-crafted from Rosewood for its acoustic properties and designed to maximize sound quality.
- Innovative design: The Infinity IRS system was meticulously designed, and much of the finished product consisted of parts that had never existed before.
- Limited production: The original IRS system was never produced in large numbers, and over time, that number has decreased even further.
What to look for in an Infinity IRS system?
As with any vintage purchase, a certain amount of wear and tear is should be expected. Because a large portion of a speakers value is in the sound it produces, the core components should be functional. Minor restorative repairs should be anticipated and performed before subjecting the vintage system to heavy use.
Content provided for informational purposes only. eBay is not affiliated with or endorsed by Infinity.
The IIIs had different woofers. Graphite or some such if I remember and there was something else different as well but it escapes me for now. But definitely the woofer system was different.
Were they the graphite injected (infused) poly cones, perhaps?
I had a set of 3Bs and had to replace the foam surrounds on the woofers like 3 times. Just something to look for. Easily done and kits are available on Ebay. Yes the woofer cones were poly.
Yes, they were polypropylene cones with little stiffening strips of graphite.
Thanks for the info!
If you do get the speakers, enjoy!!
And please let everyone here know how they sound!
I’m from HK, luckily I own a early model IRS 3, just watched paul, s video answering question about how to tune IRS v , know that paul’s system has bypassed the active crossover but adding a small box with capacitors to eliminate 100hz which possibly damage the emims, hi paul if you see my feedback here may I request to purchase a pair from your co ? The small tiny
boxes
I’m so excited to hear the differences bypassing the active crossover
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Our chief engineer makes the replacement crossovers for the IRSV and that’s maybe the same as the IRS3 but I don’t know. The little custom box was a one of a kind made by someone who no longer works for us. Sorry. Your system is gorgeous.
Thanks for your kind and nice reply Paul
May I ask the values of the capacitors inside the small box ?
Thanks 