Infinity IRS Beta Servo Control Unit help

That’s quite a score! I think the IRS Beta system is still one of the greatest speaker systems of all time, which is why I’m still using mine after all these years.

The answer to your question is: Yes and no. The midrange panels can be safely run directly from the amplifier outputs. The woofers were designed to work with the servo system and sound incredible when setup properly. That includes a proper functioning servo/xover as well as functioning control drivers - there’s one in each column. You can run the woofers without the servo and with a generic xover, but the results will be muddy and uncontrolled bass no matter what.

That leaves you a few options. One is to replace the woofer drivers with aftermarket. Unwise, imo. I think the best option is to either find a used servo (they are out there, if you’re patient) or have one built for you. There is a user in the Infinity Facebook group that has reverse engineered the servo and I think he’ll build you one for a price. Given that you got the speaker system for free, that could be quite the bargain.

The servo/xover is so critical to the proper performance of the IRS Beta system that many long-time users keep a spare.

I agree with everything stated by @cleeds 

I have 2 spares for my Betas.  One of them needs service and some cosmetic help (bought it sight unseen as a second spare). 

In the spirit of helping a fellow Beta owner, I would be willing to sell it to you.  I would recommend that it goes straight to Bob S at PSAudio for checkup and service.

Bob serviced one of mine and found it needed a pot replaced and a small caps,  It works great.

I suggest you diagnose the speakers before you decide how to proceed.  Inspect all drivers, clean and measure the LPads and factor in 500-750 to replace (at least) the SOLEN caps which are known to fall out of spec.  I replaced mine with new SOLEN to maintain originality.

Check if they still have the proper servo control woofers (2nd from top on each tower - should have a second set of connections with either a resistor or a small pc board).  Visually inspect the LEMIMs (large rectangular drivers).  Those are very hard to come by.  Replacement diaphragms are being completed for the LEMIM and all others are currently available.

After checking those and coming up with a budget, then let me know if interested on that spare SCU.  There is one on ebay right now (not mine). 

Thanks guys!!

@cleeds  Any chance you happen to know the user's name in that Infinity FB group??

@ervikingo  I've checked ebay and haven't found one, I see magicmarksey offering to service them, but don't see a listing for an actual unit.  Do you have a link or can you paste me the listing title, please??  How much do you want for yours??

keeppracticing 

Any chance you happen to know the user’s name in that Infinity FB group??

No, sorry.

I suggest you join the group: "Infinity Speaker Owners Club" and make a post. I’m sure you’ll get the info you need.

Thanks, I joined the group and it's very active, I appreciate it!

You're welcome! You are right that it's an active group and I don't take for granted that it's a friendly one, too. I have gotten some very good guidance there. Good luck to you with your Betas!

I once had (1980s) a pair of RSIIb’s—a mere shadow of the IRS, but they were wonderful.  They were seriously damaged in an Army move in 1992.  As the wife wanted more space, I went to the Modulus satellites with Servo sub, which I replaced only a few years ago.  For a sub for my new system, I went with two  Rhythmik 12” servo-subs and am quite pleased, as they handle the deep bass for my floorstanding speakers which have only an 8” woofer.  Rhythmik makes some larger servo subs a well.  I suspect the results would not match that of the original IRS, but they might be an alternative if one is needed.