help buying irs beta

Hi ima newbie just trying to break into the real hifi world.i have the opportunity to get the irs beta for a steal.i need some advice on what problems to look for and also wondering if the sunfire 400wpc 7channel amp would be okay for these speakers using 4 of the channels 2 for the upper panel 2 for the woofer towers
This is a fantastic speaker system. I still use the system I bought new decades ago and although I don't want to discourage you, this really isn't a system for beginners.

But if you're determined, here are a few things to watch for.

Woofers: The columns are designed to be used only with the Infinity IRS Servo unit and if that's not included - or it's not working properly - then the woofers are only going to disappoint. Check the woofers themselves for problems with the foam surround; these woofers need a re-foam about every 10 years or so. Check the operation of the servo circuit by having the servo and LF amplifier on, and pressing gently on the "control woofer," which is the second one down from the top. The column's other woofers should move in and out in sympathy with the control woofer.

EMIMs/EMITs: Where to start? The EMIMs are especially prone to problems, including broken magnets and broken traces on the diaphragm. Both problems are repairable, but not easily. New replacements cannot be found, although you can occasionally find used ones. Be particularly alert to substitute parts or kludged modifications made to these drivers. They are almost always awful, although there is a guy in Australia who has made replacement EMIM diaphragms that work.

I do not think that your Sunfire amplifier is likely to work well with this system. I find the best results are with a SS amp on the bottom (400 watts a channel at 4 ohms or  better) and tubes on top. There is a very low impedance dip on the mid panels, and that's a problem for some amplifiers.
Be sure to check the Emim’s diaphragms for ripples and burnt or broken traces (the traces are the aluminium strips running down the ribbon); excessive ripples and any damage to the traces is a sign of wear or abuse. Similarly, check the Emit ribbons for the same issues. The Emims of that era were the most prone to going out of spec & the magnets can start to become delaminated and oxidated, however the good news is Graeme "Graz" Keet from Apogee Acoustics can refurb the Emims and Emits with new magnets and diaphragms if you later wanted to go down that road. However the L-Emims are pretty much unobtanium & cannot be refurbed, hence check them over carefully.

Next, make sure all 8 Watkins Woofers have been re-foamed and checked for correct spec in the last 5 years, preferably by Watkins Stereo ( who do a much more thorough refurb being the manufacturer. They also provide a 5yr warranty. The foam on the original woofers over 18+ years could start to rot & eventually crumble.

Make sure the speakers come complete with the original Infinity grills (there are 4) & that the grill cloth is in good shape, servo control units + servo cables & owners manual. Also check the speaker binding posts & connections on the scu for any signs of oxidization.

One-owner pairs are rare, but i’d try to find a pair which hasn’t changed hands too many times. The more changes of ownership...the more chance of damage & ’frankin’ speakers. I’d also recommend buying Betas from sellers in Texas (have had a bad experience).

The cabinets will show signs of wear/tear for their age, but try to find a pair without obvious sun damage/bleaching and deep chips in the wood.

Finally an audition is recommended where possible. What you should listen for is firstly to make sure all the drivers are working and are in phase (ie: sound coherent). Another thing to listen for is ’panel buzz’ in the mid/high panels. Distortion or ’buzz’ in the mid/high panels could indicate an issue with the panels, driver connections, or the drivers themselves. If you do all those checks, you should be rewarded with great sound!

Regarding amps, Arnie Nudell liked the ARC Ref 300 mono’s & an ARC preamp with the Betas. Another popular combo is the big Threshold S/500Mk2 with optical bias paired with an ARC preamp such as a refurbed SP11 Mk2 or later LS26. SS Class A muscle to drive the bass panels & some tubes up top. Arnie’s now drives his IRS-V’s with a pair of PS Audio BHK300 mono’s & the BHK preamp.

If you plan to keep the speakers for the long haul, the 3 things I would consider getting done (if not already done by the previous owner(s)) are;
- Graz refurbed Emim & Emits
- Re-foam/refurb the Watkins woofers by Watkins Stereo
- Refurb the crossovers and scu, and replace the internal wiring & speaker binding posts with Cardas.
That said, the above upgrade path would not be exactly cheap, but much cheaper than a pair of high end speakers. Good luck!
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... make sure all 8 Watkins Woofers have been re-foamed ...

The IRS Beta does not use Watkins woofers, although I do know that he'll work on them. Watkins woofers have dual voicecoils, and were used in the RS 2.5 and 4.5 models - and probably some others - but not the IRS Beta or RS1 models.
Thank you all so much for the advice.I have read a handful of articles about these and do understand how challenging they can be. what I'm trying to do is get started on my dream system.and I think the time to do it is when you can. so with the help of people like you guys I think I'm going to get started. BTW I do have the basic knowledge of equipment I've just never had the means to break into the next levels of hifi ,so I've never had the need to learn about it thanks again and I hope to learn a lot from people like you over the next few years 
cleeds422 posts11-12-2016 7:12am melbguy1
... make sure all 8 Watkins Woofers have been re-foamed ...

The IRS Beta does not use Watkins woofers, although I do know that he’ll work on them. Watkins woofers have dual voicecoils, and were used in the RS 2.5 and 4.5 models - and probably some others - but not the IRS Beta or RS1 models
My bad, though I would trust Watkins to do a great job refurbing the drivers, as I would Bill Legall at Millersound.
... I would trust Watkins to do a great job refurbing the drivers, as I would Bill Legall at Millersound ...
Those are both very good recommendations!

How big is your listening room?  These speakers need a LOT of room to sound their best. 
I formerly owned the similar RS-1b, and unless you’re a masochist I would instead get a pair of Eminent Technology LFT-8b, which employs similar but superior drivers to the EMIM and EMIT in the Infinitys.
The later High Energy Emit and Emim drivers used in the Infinity IRS speakers such as the IRS Sigma and Epsilon were quite a bit better than the previous generation, as were the IMG bass drivers vs the old polypro bass drivers. Even the Infinity Renaissance 90’s were better sounding in many respects than the old RS-1b. I can’t speak for the Eminent Technology speakers, though I note from the TAS review they are very insensitive and not completely coherent.
The ET's are rather insensitive (but not as much so as the other magnetic-planar, Magneplanars), but coherency is one of it's strong points; a single driver covering 180Hz to 10kHz! The incoherence Robert Greene talked about in his TAS review was between the ET's m-p midrange driver and it's dynamic woofer. He found switching the polarity of the woofer eliminated that lack of coherency between the two, making for an extremely coherent speaker. The woofers polarity is easily switchable by the owner, the driver leads being on the outside of the bass enclosure.
The ET speakers might be a good value option, though I would take a pair of mint Infinity IRS Omega's over the ET's 5 times out of 5, but then again I am an Infinity lover. The IRS Omegas were the last Infinity IRS speakers released in Infinity's heyday in 1998 & were heavily upgraded with new Auricaps, coils, DH Labs cables etc, but are very rare in the US as they were only sold in Europe and Japan.
There are a couple of pairs available on this site, you use to be able to buy Irs betas a few years ago for under 6k, times have changed, I would check for the same things as mentioned by other members, I have IRS epsilons and also had in the past IRS sigmas, renaissance 80’s and renaissance 90’s so I know the sound of the newer infinity emit’s and emim’s, I auditioned a pair of IRS betas a few years ago and thought they sounded awesome, they had a big 3d sound stage, great imaging and the best bass I ever heard, I had to lower the bass level down to the 10 O’clock position or less for it to sound balanced with the high frequency drivers, in comparing the IRS epsilon to the IRS betas, obviously the betas had way more bass output but the bass was not as quick as compared to the epsilons bass, I believe this had something to do with the epsilons improved SCU box , the sound stage was deeper and slightly wider on the betas being that they are dipole and because of the semit, that said the newer style planar drivers used in all the above mentioned infinity speakers have way less coloration than the older style planar drivers used in the betas, to me the betas planar drivers have a ringing sound to them compared to the newer planar drivers used in the infinity renaissance 80, renaissance 90, IRS omega, IRS sigma and the IRS epsilon, If you didn’t have one of the newer infinity speakers to compare to you probably might not notice the ringing sound, that said if you have a big enough room for the batas I say go for it, I have my epsilons in a 19x15 room and it’s still too small for them.
@okeeteekid, You've owned some classic Infinities. I previously owned a pair of Reference 60's and Ren 90's. As good as the Rens were, technology moves on. My current Magico S5 Mk2's have all the magic the Rens had, but taking it much further. I've got a friend who thinks the Legacy Audio Focus SE speakers are the heir apparent to the Ren 90's...i'm not so sure.
Melbguy1, the guy I bought my epsilons from bought a pair of Legacy Audio Focus SE, I only spoke with one time after the sale was made and he said he liked the Legacy speakers because they were easier to run and there was more bass output than the epsilons, Those Magico S5 Mk2’s are beauties but can you really compare a $38,000 plus speaker to a $3600 speaker that you can buy used for $1500 for a decent pair? if the Magico’s do in fact take it much further... is it worth spending the extra $36000 plus for the upgrade? I would think the S5 Mk2’s would blow the ren 90’s away, I know a guy who had ren 90’s and thought he would upgrade to wilson audio max 2’s, when he compared the two speakers side by side he liked the ren 90’s better, he wanted to buy my epsilons, I had ren 90’s and compared them directly to the epsilons and all I could say is that everything you liked about the ren 90 is there and more with the epsilon, wider more 3d sound stage, on a good recordings the image is so good... you would think the person is right in front of you, the epsilon has way more detail from top to bottom than the ren 90, the L-emim and the 12" servo woofer make a huge difference.
I was curious about the comparison between the Ren 90’s and Focus SE’s. The Rens are a demanding load & don’t move as much air, or go as low as the Focus SE’s. Though I was amazed by the sound of the Ren 90’s at their price point, so I can only imagine how much better the IRS Omega and Epsilon sound. They are remarkable speakers. And given the similar cabinet design of the R90’s compared to the S5 Mk2’s (ie: wide, flat front baffle with a curved cabinet), their speed, staging & excellent off-axis response, I thought the S5 Mk2’s were fair game. I don’t know how Magico manage to achieve the stellar speed, staging and off-axis response of the Rens with ’conventional’ drivers, but they do. But overall, the Magicos leave the old Infinities for dead. A side by side comparison with the IRS Epsilons would be interesting though.
What are your thoughts on integrating a pair of subwoofers with a pair of Ren 90's?
I wouldn't waste my money Mitch. The Ren 90's have a couple of achilles heels. Firstly, the acoustic foam in the transmission line midrange enclosure in most examples is rotting by now & would need replacement. And there are no NOS spare parts any more for these speakers. Also, if the grilles (which are an essential part of the acoustics of the speakers similar to Avalon) are damaged and ill-fitting due to damaged or broken pegs, or a broken frame. Good luck finding a replacement as they are basically non existent. I bought a 2nd hand pair of Ren 90's from a snake in Texas called Larry Schwartz ('lwschwarz' on forums) who sold me a pair with 'textor' repairs and a damaged grill with cigarette burns on the grille cloth. As the grills were unobtanium, I ended up selling the speakers at a heavy loss. Even if you did have a pair in decent shape. Why spend as much on the speakers for a pair of subs when you can just buy a better and much newer pair of speakers?

Good luck trying to replace the sound that the ren 90’s produce for less than 10k in today's market
Yes if you accept all the caveats above, agreed you would be hard-pressed to find a better speaker under $10k.