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 ...
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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.
Good Luck and Enjoy.........
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, PassThat 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
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….
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.