help buying irs beta

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 (http://www.watkinsstereo.com/refoaming.html) 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!