IRS V in Music Room One gets a new lease on life

I wanted to share with you an extraordinary experience. As many of you know I have the rare privilege of owning a pair of speakers I have lusted over for much of my adult life. The Infinity IRS V, of which only 58 pair were ever made. I presented an entire video series on the building of Music Room One, the installation of these speakers (with a forklift) and setup. If you’d like to view the series, start with the last to make sure it’s something interesting. What’s freaked me out with these videos is the number of people viewing this last one, which now sits at 237,000. Why would a quarter of a million people watch a video on the IRS V? And because I used a snippet of a commercial track (Pink Floyd) the gods at YouTube forced me to place an ad in front of the video, for which I sincerely apologize to viewers for.

The journey with these magnificent beauties has been a long one and still there are miles to go. The room is not perfect (far from it in fact), the components of the speaker are aging, and my list of changes is long. Here’s a picture of the system from the video.

maxresdefault.jpgThe first task had been completed some time ago. I replaced all the midrange drivers with new, hand built versions. The remaining tasks were many and I had not decided yet how to prioritize them when a listener pointed out to me the top end of the system seemed dull. We soon discovered the reason: the crossover components were dying, the capacitors in particular. This revelation helped my decision to tackle the crossover next.

The crossover inside the IRS V is crudely built. It sits underneath the massive wings, hot melted in place to the fiberglass base the midrange and tweeter sections sit on. It is more than thirty years old and the components are aging, in particular the capacitors. Instead of replacing the components piecemeal, I decided to rebuild it from scratch, as if I were involved in its original design, which I was not, but I knew who was. My good friend Arnie Nudell, the founder of Infinity, had designed these beauties back in the early 1980s and I went to him for advice. He explained that the quality of passive parts like capacitors and inductors is so much better today, as they were those many decades ago, that he would replace everything with state of the art components and proceeded to give me a list of what to buy.

With shopping list in hand I approached my chief engineer, Bob Stadtherr, about the project. Coincidently to this conversation it turns out Bob had decided to tackle select custom high end audio projects for Audiophiles in his spare time. So I hired him to design and build a new set of crossovers from scratch. My instructions were simple: no compromises. Bob went to town. My fellow IRSV owners got wind of what I was up to and jumped in without hesitation. Soon Bob was building multiple crossovers for IRSV owners on Saturday and Sunday and we all waited with high expectations.

When Bob tackles a project it is with all feet in and perfection is a given. It’s what he invests in PS Audio designs as well as whacky custom projects people who are fanatical about their high end systems ask him to build on his days off. My only stipulation with other IRS owners engaging Bob to build their crossovers was simple: just make sure I am first.77_gif It’s good to be king. happy-048_gif

After a few months of work (there are only so many weekends he can contribute) my crossovers are finished and connected. The improvements are breath taking, I am still breaking in the new boxes, learning how different the speakers now sound, and getting adjusted to just how much of a difference passive components make in speakers. I knew they mattered, by am reeling from the degree to which they are improved. It is not like a new speaker, yet between what I was used to and what I have now, I doubt I would recognize them as the same.

One of the first decisions Bob made was to go external with the components. Instead of living in the midrange/tweeter panel bases, where they are subject to vibrations from the sound, he built custom boxes that sit behind the wings. And instead of the old non-polar electrolytic midrange capacitors Infinity used so many years ago, they were replaced with huge film versions. Bob then designed a custom circuit board and hand built each crossover into a true work of art. Below are pictures of what now the BHK Signature power amplifier happily drives.

I don’t yet know the true measure of these speakers. New passives need time to break in. But cold and out of the box, the system has taken an extraordinary leap forward and I am thrilled. Bob is now finishing the other crossovers anxious IRS owners are waiting for. I am always excited to see what miracles he helps people’s systems with, those lucky enough to engage him in custom work on their equipment, but for now I am the lucky one, enjoying what is essentially, a whole new system in Music Room One.

Thank you Bob. This is genius.


Very nice! Bob does wonderful work, my compliments (and then some). Was any consideration given to using battery biasing. e.g., like Audioquest uses in their cables and Vandersteen uses in their High Pass filers? That would seem to overcome some of your concerns with passive part break-in, correct?

It wasn’t considered but probably should have with wires. I’ve not heard of that being applied to capacitors. We recently took a tour of Audioquest and learned about what they’re up to with caps, and it’s really interesting. It involves some magic formula Garth came up with to form them with current and voltage. Fascinating stuff, though proprietary and secret.

I imagine just swapping out the electrolytics would be a huge improvement. Even when I upgraded my Electovoice PA crossover caps with some mildly better film 'n foils the difference was substantial. I am a fan of the low DCR flat foil inductors as well. The cost involved in a crossover like this is, to say the least, substantial!

I’m impressed. And shocked that you give Bob Saturday AND Sunday off. Next he’ll be asking for national holidays off too. And vacation. And sick days. It will never end.

Interesting binding posts. WBT?


You might be interested in this; 2 articles from 6Moons, concerning Bill LeGall of Millersound (who offers one of the top speaker rebuilding services in the country):

Bill LeGall pt. 1

Bill LeGall pt. 2

Bill LeGall owns pairs of Infinity IRS-III’s and IRS-V’s. Both personally tweaked and modded by Mr. LeGall. Some of the tweaks are covered in pt. 1, of the links provided.



One other thing,

There is a gentleman, in Australia, who builds replacement ribbons and panels, for older Apogee Acoustic speakers. His name is Graeme (“Graz”) Keet. Besides designing and building replacement parts for Apogee, Graz also designed and built new replacement Infinity EMIM diaphragms (modeled on donated Infinity diaphragms). The new diaphragms received very good reviews, at different internet audio forums. Measurements were impressive too; a bit flatter and more extended, than the original Infininty EMIM’s. Graz still occasionally produces new EMIM diaphragms, once there are enough requested to make a short-run feasible. So, new diaphragms, could be another step in bringing your IRS-V’s closer to like new.

Apogee Acoustics

U.S. Dealer

Good Luck,


stevem2 said I'm impressed. And shocked that you give Bob Saturday AND Sunday off. Next he'll be asking for national holidays off too. And vacation. And sick days. It will never end.
I know. Other employees will read this and demand their weekends and holidays off as well. What's the world coming to?

Hi Paul,

Those new crossovers really look the business ! I was wondering if you ever rewired the drivers and what wire you ended up using??

I haven’t yet rewired the drivers, that’s next on my list. It’s been suggested that Cardas would be best. I honestly don’t know, but suspect anything would be better than the 30 year old Monster zip cord they’re wired with now.

I’d suggest you contact Alert Von Shweikert for a bit of his speaker wire.

I just had a flashback … Monster Cable and a lovely shade of verde green inside the jacket. Time to get that crap wire out of there!

No kidding. So what’s the deal on Albert’s wire?

I’d ask Galen for his suggestions.77_gif

I think you will be shocked when you get rid of that old oxidized green monster crap…I’d even say that until you do you really won’t be hearing what the new crossovers are doing or what the IRS’s can really do!

Cardas would be a good choice… I’m sure George would be more than happy to discuss it with you, I’d also suggest calling Chris at VH Audio he has lots of good stuff Acrotec, Furutech, Oyaide… etc

Interesting reading in the recent TAS or Stereophile (can’t remember which one) that George Cardas apparently supplies a lot of the drawn copper used by many other audio cable manufacturers. I suspect between him and Neotech they probably have most of the market covered in the U.S, although I have no real proof of that. Not that that has anything to do with what Paul should do.

Paul McGowan said No kidding. So what's the deal on Albert's wire?
He wires his newer speakers with some amazing wire, and he make IC's and speaker cables with it. Give him a ring!

Paul, I am just wandering into this forum for the first time. Interestingly, when I listened to the system a few weeks ago it sounded a whole lot better than I remember it from my earlier visit, at which time I was honestly a little underwhelmed. That would for sure have been before the new crossovers and midrange rebuilds. Now you are really getting somewhere. The seating position still feels to me like it’s too close to the speakers, but the room is only so big. :)

I totally remember that old Monster cable turning green. All during my graduate school years I couldn’t even afford to replace it with new monster cable, much less something better. :(

Thanks Bob, yeah, impressive as they were back then they did leave some underwhelmed because of the broken crossovers - which had been slowly degrading over time. They still worked well for me as a reference tool - their ability to differentiate between good and bad changes in electronics was still exctraordinary - but their lack of top end because of failing capacitors really was limiting.