Infinity IRS Betas - proper amplification


I have read these forums for years and I am finally joining after
buying a system that I think demands more commitment to this hobby than I have had before. I am hoping for a contrustive and thoughtful discussion of what my best/most reasonble ($) choices are going forward. I do ask that people not snip demeaning responses about things they might consider obvious. But solid probing questions are welcome. 

My room is roughly 16x24, with a vaulted ceiling that passes to an upper floor running 8’ high from the 24’ wall where the speakers will point up the vault. (Day 1 -any way) 

My current systems are all varying degrees of vintage. Long story short...divorce...Very early Cornwall’s...upgrade to separates (mac MC2100s bridged) off a Decent Yamaha HT integrated., added a Miller kriesel sub and off I went....as is
great but “Klipsch need tubes...” enter mc240, c20, mr71....(now my bedroom system, its a big room) primarily CDs.....scored a roached set of
JBL Apollo 51s,now redone with an N1200, D130 Bs and the standard horn...enter highly modified mc60 monoblocks run though a sunfire theater grand 1 always in source direct off a decent dedicated music server (nothing special laptop) I
dont hang in a huge audiophile group, but some musicians are in the
mix, aside from the magnolia no holds barred theater room I had never heard
anything that made me smile broader than my stereo playing. Saturday night  was
”One Slip” played at (-5dB) (I live in the woods) It was really special....UNTIL....

Last week a local stereo buff listed his one owner excellent condition 10/10 aersthetially last production run IRS Betas, he asked for half of original retail....I now own them.....

Now I am at the OMG, what have I done....he had an easy 15k into his system not including changes over time. Yes, I am getting to the
obvious

What now! I am going to dust off the 2100s for the low end, the mc60s even into 4
ohms are not enough (he ran a sonic frontiers 2 ($2k if I want it (sovetek kt88))) I don’t think I need to worry about the demand on the 60s (PLEASE CORRECT ME IF THATS WRONG) though I am concerned about the polarity(?) as they are heavily modified with filter tubes replaced with filter caps and a huge capacitor in the signal path to
punch harder (I am not an electronics guy but the techs I have taken them to over the years all say they sound and test tight and clean. (I agree ;)

i have tried to be inclusive and I hope folks will have constructive thoughts to share, obviously this won’t be cheap to pair up and I would prefer to learn before I spend $$$.
 Lastly....I Love most music and see live stuff at least twice a month.I  listen to deep earthy blues, ska, some jazz, but more on the funky side. Smiths/cure/stone roses...very little hardcore outside of live shows (But, Ride On by Bon Scott is
a beautiful thing) I also host about 1 party that usually evolves to dancing.....

Wayyyy more than I planned to write...with my thumbs! 

The typos are....just that😮

respectfully,
Walt
9535be84 09cb 413f b5d4 fce1a90e6d56entomologist
Forget about tube gear.Those IRS's need an amp that can drive 2 ohms and put out a lot of current (amps) to really come alive! Think Krell, Levinson, Pass ...
Save your tube gear for your JBL's! Those C51's are really something! 
To get input from Infinity owners, try the Infinity forum at AudioKarma. These guys are into vintage infinitys and can recommend amps that have worked well with them.

http://www.audiokarma.org/forums/index.php?forums/infinity-loudspeakers.129/

Good Luck and Enjoy.........
roberjerman
Forget about tube gear.Those IRS's need an amp that can drive 2 ohms and put out a lot of current (amps) to really come alive! Think Krell, Levinson, Pass
That hasn't been my experience with the Beta system, which I've been enjoying since I bought it new back in the early '90s. A beefy tube amp will work on either the top or the bottom. For the woofers, a CJ Premier One sounds terrific, although most of the time I use a Bryston 4B, which is also great. Tubes also work on the high panels, such as an ARC Ref 150. but a good solid state amp will also work well on the HF. The Beta system was actually designed around ARC tube amps and preamp and, iirc, the manual specifically mentions the great ARC SP-11. The system is best connected with the HF amplifier going directly into the HF panels, and only the bass amp connected to the xover/servo unit. That's where you need to be certain that the phase is correct.
Thank you for the input, I will hit the Infinity owners group and see what’s out there as far as equipment recommendations and then see what is actually for sale at reasonable prices. I am leaning to tubes up top and SS on the bottom end, for sound and monetary considerations also seems a pretty consistent recommendation  (I have no idea what 2-300 WPC would cost in tubes, but I can guess!)  The seller had his room dialed and clearly had experimented a lot!. As to the JBLs, I will never sell them, I actually was thinking about leaving that system in place and adding the Betas in the mix. Then I can choose which sound I want, but that seems a bit overkill. Probably sell off the Cornwall’s.
I ran my Betas with a McIntosh MC352 on the subwoofer panels and a Threshold S/100 on the upper panels.   Then replaced the Threshold with a McIntosh MC452.   

Yes, I am sorry, almost $9000 of amplifiers.   

The more power the better.  Any amplifier that ‘doubles down’ would be a good direction to go.  Eg 100wpc at 8 ohms, 200wpc at 4 ohms, 400wpc at 2 ohms or a McIntosh with autoformers.
On my IRS Betas I used 4 mono Jeff Rowland 7 and was very happy. I still use one pair of Rowland 7 for the Base towers , the top end I run a Pass x250 that works fantastic at low levels the detail and musicality is incredible however when pushing the amp to leave class A , quality deteriorates a little. (compared to some other power amps they just sound very bad when the speaker demands control).
Other Power amps I would consider for a IRS Beta system is
PassLabs 100.5 ,
Jeff Rowland 7 ,
Threshold has some option ,
MBL I always liked but was not convinced ,
AVM 8,2 would like to explore ,
Krell I never explore due to the harsh sound ,
Usher had some amp that looked OK but don't know enough about ,
Mcintosh I love the look and build but the sound never impressed me ,
Some old mark levinson ML 3

PS;
A. The biggest improvement in sound on my IRS Beta set up I got out of my pre-amp the Legend Audio L2 signature (now Von Gaylord Audio) and a DA from them plus interconnect cables. (=>tube for pre-amp!!!)
Tweaking the IRS Beta setup to be very revealing leads to most not perfect recorded music sound terrible , for that reason I have additional setups HHScott with Klipsch Corner-horn and a Legacy speaker with a Jadis amp.
B. While my amps were out for repair I had a workable experience with my old Yamaha MX1000 for the Base only (could not listen to it on the panels).
C. I used a MC250 (SS),MC 75 (tube), MC275 (tube)for the base as well but it sounded very muddy , your MC2100 may work for the base until you get something more serious.
Hello Walt and other Beta owners. Around new year 2019 i payed an advance to buy a Beta system. The sale was cancelt by the seller. the system was a G serie with around a G000850 serie numbers for the bass towers to not be exact. So i wonder how many Beta's are made. I don't find it on the internet. Last time a saw a picture with number G001890 so you can please check your numbers and let me know….
Thx
 
For the IRS Beta cheapskates out there, an Adcom GFA555 will drive the woofers, and I even use an old SAE A502 on the panels. You can find each of these for around $500. I originally got some VTL 300 tube amps, used for $2500, but even after spending $800 to upgrade them at the factory, they have been hard to keep going. They sounded a lot better though, driving the panels.  G000865 and G000867 are the woofer serial numbers.
A real good amp for woofers is the Electron Kinetics Eagle 2, if you can find one in good working order (they are by now pretty old).