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A description of IRS 4.5s

Let me throw in one more thing about these:

Amplifier selection. You do get much different sounds on these w/ amplifiers. Much more finicky speaker than the norm. I love them w/ tubes. Audio research/conrad johnson for the Mid's. I switched to SS for the bass because I never did like the tubes there. Use a krell now.

The one thing I didn't do was to go monoblocks. I've heard CJ monoblocks drive these and it's better than the Bi=amping I do. There just aren't a whole lot of tube monoblocks to choose from.

You also need a big room for these speakers. Lots of open space. My previous house had 9 foot ceilings and the old plaster walls and not drywall. There was a noticable difference to what I have now.
 
robertk, you raise an interesting poiint. My ceilings are over 9 feet high and the walls are plastered (not drywall), with the plaster over either a realtively soft reinforced cement or brick-and mortar substrate (depending on the wall), which insulate sounds extremely well between inside and outside, and even between one room and the next. I think my RS IIs sound wonderful in this space, although a little more width to the room would help (it is relatively long and narrow). I wonder how different they would sound with different wall surfaces, should I move later. Could you comment more specifically on the sonic changes you observed when you moved from one type of wall surface to the other? Thanks.
 
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I had an 1840 gothic revival house w/ lots of space and superior construction compared to present day stuff. The house now is a 30 year old brick colonial w/ typical drywall and hardwood floors, etc.

House #1; 9 foot ceilings dropped down from original 13 foot. Had one of those drop ceilings put in. Room was 16x25 unobstructed. Hardwood floors w/ the 15" wide planks of hardwood--not pine.

House #2; 8 foot ceilings unobstructed 12x18.5 Drywall ceiling of course & those pine floors they love anymore.

Sonically, I would say the difference you get is equal to a major upgrade in cables. Specifically, the order of magnitude or refinement you get from switching from 1980's straightwire cables to 2000 Mit mh750 and Mit 330 interconnects. Fairly significant.
That said, it was something I really didn't think enough about when I bought this particular house. I had to have a place big enough for a seperate stereo room in the house---no chairs, just a few lamps and lots of vinyl.

But when it comes to stereo, you never want to take a step backwards and it is a step in that direction for sure. I've recently started buying my 11 year old son some older stuff for his own somewhat high end and one thing I got him was a pretty decent cd player--top of the line denon.

Hooking that up and playing it thru those infinity speakers just plays into that midrange glare I have in this house and pretty much makes it unbearable. I really don't think these speakers handle digital as well as analog & my particular setup is 100% vinyl though.

I did hear my speakers driven by the conrad johnson premeir 5 monoblocks once. It was terrific, but I also heard those cj's drive some accoustat model 8's (8 foot tall jobs) and that was better than the sound I get.

Hope this helps.
 
Here's an interesting variant on a 4.5 currently up for sale. Note how the EMIMs and EMITs are positioned straight down the middle of the upper panel, rather than being offset to one side like the regular ones.

For such a limited production speaker, Infinity sure managed to produce a lot of different variants.

David
 

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David,
Good job spying this. Hmmm, I am becoming amazed myself. It is almost as if they had a stock cabinet with crossover network and an on demand speaker array. I can not imagine the sonic difference between this array and the offset array, but there must be a reason for the varient. If I lived in California I would be a poor man with lots of Infinities.
Vito
 
robertk said:
I had an 1840 gothic revival house ....<snip>...I really don't think these speakers handle digital as well as analog & my particular setup is 100% vinyl though... <snip>
Click to expand...

I have to agree about not handling digital well. I like to blame it on the speakers being so revealing that you hear all the compression and such that detracts from all but the best-made digital recordings. A few of my CDs sound fabulous through these, but 1/3 to 1/2 of them become unlistenable. Vinyl sounds wonderful. Cassettes sound good if done properly with high-end gear and Dolby; otherwise you can hear the hiss!
 
Vitopanch said:
If I lived in California I would be a poor man with lots of Infinities.
Vito
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Hi Vito,

What do you mean, you DO own lots of Infinities!

All these variants have me intrigued. It would be fascinating to listen to some of them side by side and see how the design differences altered the sound. I wonder if the Infinity folks even knew how their modifications would affect the speakers, or if they just did whatever the customer ordered.

David
 
Vitopanch said:
Nakdoc,
Whoa, 6'5's. I have never heard of those. Were those the only two that were made to your knowledge? By any remote chance do you have pictures? Also too, I have been seeking knowledge about a design difference in the RS 4'5's.
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Sorry I missed this post. You are right, the 6.5s don't "exist", but there is at least 1 pair somewhere, in Indianapolis most likely. John Nork was a senior Absolute Sound writer, and Infinity sent him the 6.5s. John takes forever to review equipment, and he happened to be my boss at Hi Fi Buys (that he was part owner of a store never quite made it into TAS) John told Nudell he loved the speaker, except the woofers were slow. The first pair of 6.5s had 4 woofers, more height and more EMIMS. It used an electronic crossover (which we tried with 4.5s , too) . Nudell had the 6.5 woofer modules shipped back, and Nudell revised them with 24 6" woofers all in one face of the cabinet. We got to play with them 4 or 5 months in Nashville, using ARC, Threshold, Carver (a joke) , and finally a Nikko! The Nikko was the best amp, go figure. I do know we were trying to sell the speakers, so I have always assumed they were production models. Sorry I have no pictures.
We had strong debates about the 2.5,4.5, and 6.5 lineup (all in one room!) The 4.5s were just plain difficult to place in the room. 2.5s were easy, and the 6.5s .... well they just dominated.
 
Vitopanch said:
A very bad thing just happened. a 'parter out' just bought them. Man o Man this is a shame.
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Vito,

Man, that's a pity. I hate to see speakers this unique get broken up. Being for sale in SoCal, you know they would have found a home. Very sad.

David
 
phaedrus said:
Here's an interesting variant on a 4.5 currently up for sale. Note how the EMIMs and EMITs are positioned straight down the middle of the upper panel, rather than being offset to one side like the regular ones.

For such a limited production speaker, Infinity sure managed to produce a lot of different variants.

David
Click to expand...


Well I have good news here. I spoke to the person that bought these and as it turns out he is not going to part these out. Man, what a relief. He told me that the reason that he snagged them is that they ARE unusual. Get a load of this. He says that they are a tri-amp variation that have no crossovers and all of the Emims are in parallel for 1 ohm load and same with the Emits. The 2 voice coils on the woofers are in series and then paralleled with the other woofer for a 3.5 ohm load.

This is one wild variant. He says the center arrangement theroritcally will provide more precise imaging in certain environments.

Vito
 
Vitopanch said:
Well I have good news here. I spoke to the person that bought these and as it turns out he is not going to part these out. Get a load of this. He says that they are a tri-amp variation that have no crossovers and all of the Emims are in parallel for 1 ohm load and same with the Emits. The 2 voice coils on the woofers are in series and then paralleled with the other woofer for a 3.5 ohm load.

This is one wild variant. He says the center arrangement theroritcally will provide more precise imaging in certain environments.

Vito
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Vito,

Wow, that is a wild arrangement. Got to be interesting to try and drive that load. Glad to hear he's not going to part it out.

Wonder why they designed it that way? I can see the rationale behind eliminating the passive crossover, but paralleling the EMITs and EMIMs? Any thoughts on what they were trying to achieve?

Well, at least they're going to survive, hurrah!

David
 
Vito-

Great news on the non-parting out! Please invite the owner to join AK, and let everyone here know how they sound, what he's driving them with, etc.

The more 4.5, 1b and Beta owners we have here, the better, and the more likely we'll finally get to chat with a real live IRS owner!
 
Didn't Audio Research design that one tube crossover of theirs--don't recall model number--about 25 years ago with infinity dipoles in mind? Seems to me it was a high end design and there are some out there, but are rare to find. I wonder if this sort of crossover network could tackle this type of issue?
 
robertk said:
Didn't Audio Research design that one tube crossover of theirs--don't recall model number--about 25 years ago with infinity dipoles in mind? Seems to me it was a high end design and there are some out there, but are rare to find. I wonder if this sort of crossover network could tackle this type of issue?
Click to expand...

Not sure if this is what you were thinking of, but I got an AR EC-4 3 way tube crossover when I got my ServoStatiks. It had originally been set up by the ARC folks for triamping the Servos. The owner had been using it in place of the stock Infinity crossover.

Kind of kludgy compared to more "modern" crossovers but he seemed to love it.

David
 
EC-4 isn't the right model number. Just cannot recall what it is, but I think it was for the infinities and maggies. I'm thinking 81-84 or so, & lots of folks had went with that dahlquist dq 10 x-over network & liked that one better than infinity.

I couldn't afford that audio research tube unit at the time, but they sure did put some nice tubes in their units back then. You'd probably go half broke re-tubing that Audio Research unit today--especially if they have those telefunkens in there.
 
I have the RS4.5 and just uncrated them today. Haven't heard them but will set up tomorrow. I have seen two slight variations with the cabinets. The earlier (stereophile review of 1979) have plain sides. My speakers' sides have little wooden round domed caps at the top and bottom of the woofer section. My serial #s are 7307738 & 9. Anyone know a year? I am hoping they are later as I read they got better as the line progressed.

Also, I need to clean what appears to be 25 years of dust and cigarette tar residue off the EMIM foil. Any tips on a good outcome? The foil is all intact and not peeling off anywhere so I want to be sure and do the cleaning right.
 
mywifespissed said:
I have the RS4.5 and just uncrated them today. ....My speakers' sides have little wooden round domed caps at the top and bottom of the woofer section. My serial #s are 7307738 & 9. Anyone know a year? I am hoping they are later as I read they got better as the line progressed.
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Heh, took you awhile to get them uncrated! Hope you like them.

I'm trying to visualize what you're talking about with the "wood round domed caps". Can you post a picture of it? Neither of mine have anything that sounds like it matches that.

I'm pretty sure yours are late in the production run; those serial numbers are later than either of my pairs.

David
 
Yeah. I was building a room solo while working 50 hrs. a week plus kids. Pathetically small space for the 4.5s. I think anyone coming to visit would get a laugh out of these beasts packed in a 7' 9" width. WAF sent me and the speakers to the doghouse. I was happy to see the delicate thick black foam is perfect except for one marble sized ding where a finger must have landed. I will send a picture as soon as I load the image software onto my new computer.
 
Here is the pic phaedrus. I thought the domes were wood until I touched them. Brass maybe?
 

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