Choosing best Vintage receiver for Infinity RSb speakers?

Vintage71

New Member
Hey there, new here so feel free to point me to any existing threads as needed. Please pardon the length of this thread.

First, I am pretty new to vintage audio, but love the designs and generally love vintage things, anyway, I have recently inherited a set of RSbs, one is missing the woofer and the other woofer is shot. I plan on finding a replacement woofer (which I have currently identified), and re-foaming the other. They come from the original owner so I know they have been heavily abused by sound in their lifetime and serviced at least once, but the boxes are clean and are also mounted on those flat metal stands. Per the "RSb Midrange Madness" thread, I will also go over the crossovers.

All of that said, I will eventually need a receiver to power these. I will take into consideration various factors for the final selection, but looking for technical synergy first so as not to blow the receiver, or the speakers, I don't want too much power or too little, I need the Goldilocks match up. I will play all types of music from Metallica to Mozart violin concertos, but mostly rock and roll.

One more item, I am not an electronics or audio tech by any means, but am quite capable and unafraid so please understand my approach to thinking about these things comes from a place of what seems right based on my research and 'common sense', but not a trained or experienced angle.

Per my research these seem to be the factors of concern, please give any input, add, or debunk as needed:

Note: My technical references are the infinity-classics.de manual for the speakers and hifiengine.com database for receiver specs

1.) RSb are 4 ohm (but may actually run as low as 3.4 per info taken from another thread/other research). my understanding of a general approach to this sizing is the 8 ohm wpc rating should basically be doubled to figure the 4 ohm power requirement, so with a 25-150 Watt RMS rating, this logic tells me I need a receiver putting out 12.5-75 watts (based on the 8 ohm X wpc ratings), but with unknown ohm variances, I may want to stay a little less than 75 watts; also, that the receiver needs to be able to handle 4 ohm speakers.

2.) I have read that these speakers may need a much higher, maybe along the lines of 100W receiver to drive them (another forum, mostly covering newer equipment). Could this be due to the fact that newer equipment vs vintage are manufactured and rated differently?

3.) I have read that these speakers require a high power amp to drive them properly, what qualifies an amp as 'high powered' in relation to this discussion?

4.) I have read that these speakers can be amp killers if not properly sized (reference to an AK thread where someone blew an Pioneer SX-950 and a Pioneer SX-828). Per my research, it seems that these should both work quite comfortably with the RSb. Any thoughts on why this might have occurred?

5.) The space for my system will not be huge, but I would like to plan for the future which may mean moving the rig outside for a yard party, or eventually moving into a much larger space . The point of this comment is that the system may end up running at a high level for long periods so needs to be able to handle that task as needed.

Receivers that seem to fit the bill include: Pioneer SX-750 and up, Marantz 2270 and up, Yamaha CR-1020 and up, I am sure there are Sansuis that will fit (and others), but I have not done as much research on those, yet.
- I don't currently have a budget, but would certainly like to keep things cheap/affordable. I don't need to do this so have time to look, will be in and out of the thrift/SA/craigslist, etc..
- Would like to find something serviceable, meaning parts are not impossible to find or impossibly expensive
- I love the beautiful silver faced gear and this is what I am looking to find, vintage, late 70's early 80's
- Of course I would like something with as many features as possible for the money, that will allow me to attach a turntable, cassette, possibly run a CD player and/or iPod if possible, loudness control would be nice, etc.

Overall I am looking for attractive, synergistic, optionable, serviceable, affordable match up for the RSbs.

Thanks for any comments!
 
"Receivers that seem to fit the bill include: Pioneer SX-750 and up, Marantz 2270 and up, Yamaha CR-1020 and up, I am sure there are Sansuis that will fit."

That is a good starting list and there are some vintage Sansuis that would work well too.
JMO--I wouldn't go much smaller than the Pioneer SX-750.
It wouldn't hurt to get a receiver that is rated for 4 ohm usage but that's just me.
Depends on music genre and loudness levels.
I used several receivers with my RSM's (one step up the Infinity ladder from the RSb), all rated between 80 to 125 watts per channel.
 
Thanks for the input goodolpg, sounds like I am on the right track. The intent is not to be killing it all of the time, but there do come those occasions, and I do like hard rock... I think my biggest concern is the 4 ohms and the drive requirements, and reports of blowing out equipment with 'mismatched' gear. The goal is to safely get the most out of both pieces of equipment with the proper marriage, that balanced 'synergy'.
 
RSb speakers don't need crazy powerful amps. I have a Denon PMA-860 and the thing has a ton of spare power for these speakers. It will cleanly drive them far louder than I would ever desire, and it's only rated at 80W @ 8 ohms and 135W @4 ohms. I would guess that any receiver that is rated for 4 ohms and 75W would be plenty to drive these speakers, so you should be perfectly fine. It's really the higher up Infinity speakers that are amp killers. The RSbs really aren't that hard to drive.
 
I had some RSBs that really rocked with a Carver "the receiver" which is something like 120w. They didnt sound as good with a Sansui AU 317 which was probably a little under powered. I love how fast and punchy sounding the RSBs were!
 
1. Many vintage receivers could not double their output into 4 ohm speakers. Infinity knew what they were doing when they recommended 25 to 150 watts.

2. It's partly the ratings differences between the older stereos and modern AVRs, but many speakers perform better with more power, some say it controls woofer movement better.

3. 150 watts (or more if you're careful...)

4. No Idea! Infinity has a reputation for making "amp killer" speakers but really only a few models were QLS-1, RS 4.5, and Kappa 9 come to mind. These Infinity RSb aren't considered amp killers. Maybe the receivers were old...

5."Pioneer SX-750 and up, Marantz 2270 and up, Yamaha CR-1020 and up, I am sure there are Sansuis that will fit (and others), but I have not done as much research on those, yet."
You are on the right track, consider some other "off" brands too, like Technics, MCS, Kenwood, Realistic, Onkyo, Tandburg, and Harman/Kardon, many were very well built, attractive, and sound great, the bonus is that they are cheaper because they are less "collectable".

Let us know what you decide!
 
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I ran my RSM's with a Lafayette LR-9090 (90 wpc) for several years until the woofer foams rotted in 1993.
After bringing the RSM's back to life in 2011 I ran them with a Lafayette LR-120DB (120 wpc) and MCS 3125 (125 wpc).
I also tried them with a Denon DRA-635R (80 wpc), while I didn't hear any bad things with that combo, I decided not to continue on with the Denon because the Denon was rated for 6 ohm usage. That may have been me just being a little cautious.
I agree with the others, the RSb's aren't considered amp killers.
 
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All, thanks for the put so far, feeling a bit more at ease with your comments on the RSbs. I really love the look and feel of the silver faced gear but much of it seems a bit low wattage, so after playing with some numbers on the Crown amplifier calculator (http://www.crownaudio.com/en/tools/calculators), I think I will look for something 50W minimum and maybe add an amp to the mix if needed.
 
I bought a set of Rsb speakers in the early 80s and kept them for over 30 years. I first used a 70 WPC Sansui receiver and it would heat up and blow tweeter fuses. In 1984 I bought Carver M400t power amp and it ran cool and I never blew another tweeter fuse. The Carver amp is till going strong. I sold the Rsb speakers in 2014 for what I paid for them more than 30 years ago. I guess inflation took most of the value but they served me well. You will need a high current receiver if you play loud. A friend's 150 WPC Yamaha receiver shut down in 1984 playing these. However if you change the woofer you may have no problems, but the crossover may need changes depending on the woofer you choose.
 
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Any of the Nakamichi receivers with the Stasis circuit licensed from Threshold would drive RSB's easily and sound great doing it.
 
I biamped mine that I built from scratch using the RSb drivers and modified crossovers. I have a 130 watt Yamaha natural sound receiver driving the emits and mids and using the preamp out into a sonance high current 240 watt driving the bass woofers which can go down to 2 ohms. This allows the Yamaha to stay in class A and the sonance to independently drive the woofers. You can search this forum for “RSb Reincarnated”. I also added a rear firing emit with its own separate crossover. You could get a nice Luxman R-1070 and pick up a sonance and be off to the races and never look back.
 
Separates are the way to go here. I used to have these and receivers that are rated for 8ohm only wont do well with these speakers. I know some vintage receivers have a switch on the back for 4ohm but...
 
To keep things simple I run my 8ohm speakers on my vintage 8ohm receivers. And run 4-6 ohm using my separates that are rated @4OHM and no less than 250WPC. This also brings the best out of those 4-6ohm speakers. Short story: When I started collecting I hooked up a pair of my Cerwin Vega DX9 using my beloved unrestored Pioneer SX 1010. Cerwin Vegas are rated @ 4ohm. After a few songs turned up about half on the dial I checked the 1010 and it was hotter than a frying pan so I shut it off right away before that blue smoke appeared-sounded fantastic. So I learned some lessons along the way and got educated here on AK. Since then my DX9s are restored being powered by a Soundcraftsman A5002A and wow is all I can say. The 1010 is also restored and in my main system powering a set of Pioneer HPM 100 modified and its a conversation piece when folks come over for a listen. Hopes this helps? Vintage gear is addicting especially if from that time.
 
Hi Vintage71,

high power amp ?

this could be 2 things,
high watts or high current,
not all amps have both.

to get that you would typically need to go for separate pre and power amp.
cost would probably go up, but sound quality definitely will.
 
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