What the!? - Infinity RS 1b's

Hey guys, I just came across an interesting piece of info from the great MagicMarksy! According to him in regards to the RS 1b's, ONLY the 3rd EMIM down produces most of the sound. The other 6 EMIMS act as lower mid-range drivers. I currently own the RS IIb's and these speakers do the same thing, but there are only 3 EMIMS (1 playing the higher frequencies and 2 playing the lower). As much as I love this for the IIb's because it adds separation, I don't think it would sound good to have 6 EMIM's only playing the lower frequencies. Current owners or people who have heard/owned RS 1b's, is this actually true and how does it sound? According to MagicMarksy, because 85% of the sound comes from the third EMIM down, he has seen many 1b owners blow the EMIM or even catch it on fire!!!

This is directly from him:

"The RS-1 and RS-1b are actually 6 way point sources, with the point source centered at the 3rd EMIM down ( and this single EMIM actually does 85 % of all the work of the whole speaker system - yes out of the great big RS-1 and RS-1b system you are almost exclusively listening to one 3 in x 5 in EMIM, all the rest of the speakers just supplement this one driver). Let me explain further.

The RS-1 and RS-1b's have crossovers at 150 Hz, 700 Hz, 3000 Hz and 8000 Hz.

The two woofer columns, each made up of 6 standard 8 inch woofers function below 150 Hz.

The top two, and bottom 4 EMIM's operate from 150 Hz to 700 Hz.

The 3rd EMIM down from the top operates from 700 Hz to 3000 Hz.

The top and bottom from tweeters operate from 3000 Hz to 8000 Hz.

The center front tweeter ( with the small CAP on the front ) actually acts as a Super Tweeter and only functions above 8000 Hz.

The rear tweeter operates from 3000 Hz on up."



WHAT DO YOU GUYS THINK??

Well if that applies to the RS1B's then it would also apply to the RS2b's. Truth is there are 10 octaves in music. This one driver covers only 2 of those octaves. By comparison the RS2.5's cover 5 octaves with 2 EMIM's . To say 85% of the music lies within the range of 2 octaves ( 700HZ- 3000 HZ) could cause some head scratching. If someone blew their EMIM and it caught fire I would say there was something else wrong. As in very underpowered for the volume level or bypassing the fuse going to that driver. I play at high volumes on my 1B's and have never had a failure. With that said I have seen all 8 drivers fail on a set of 4.5's. How I still don't know. The RS1B's had a purpose design and it was not to be a line source.As the frequency gets higher the sound source gets smaller. They have tremendous imaging and off centre response.If you push them hard you can make that one EMIM sound a little aggressive. This was improved with the GRAZ mid I installed. I have a system upstairs with the 1B's and RS4.5's downstairs with a backup pair of RS2.5's that I rotate in every now and again. My wife flat out prefers the RS1B's whereas depending on the music I happily going between the 2.

Yes, Dr Marks is correct. Technically, there is only the one 'true' midrange EMIM, in the RS-1A/B. From the Infinity Tech Manual:

"• Crossover Frequencies: 140Hz, 700 Hz, 3,000 Hz, and 8,000 Hz"

http://infinity-classics.de/technik/manuals/RS_I_technical_sheet.pdf

So, that 3rd EMIM covers 700 Hz to 3K Hz. The other 6 EMIMs play between 140 Hz to 700 Hz. As stated, mid-bass, lower midrange. Kind of a collapsing line source, as frequency response rises.

Now, whether Dr. Marks is correct in his beliefs, concerning the drawbacks of this design, is open to debate. The RS-1s operate as designed. However, they are not Mini-IRS speakers.

Hm, interesting, i always assumed the RS1b is a line source like the IRS V, apparently i was wrong.

It still makes me want a RS1b though, the seem interesting. Sadly i had the chance to get some, but missed it...

I wonder why Arnie would have done this, since the EMIM's on the IRS V do the entire mid-range and mid-bass. I would love to read a comparison between the RS1b and the IRS V (and yes i know it would be unfair)

Well said. +1. This applies to the Betas as well. Only one Emim for the mids. This is why Dr Marks has experimented with some of his own designs.

StimpyWan said:

Yes, Dr Marks is correct. Technically, there is only the one 'true' midrange EMIM, in the RS-1A/B. From the Infinity Tech Manual:

"• Crossover Frequencies: 140Hz, 700 Hz, 3,000 Hz, and 8,000 Hz"

http://infinity-classics.de/technik/manuals/RS_I_technical_sheet.pdf

So, that 3rd EMIM covers 700 Hz to 3K Hz. The other 6 EMIMs play between 140 Hz to 700 Hz. As stated, mid-bass, lower midrange. Kind of a collapsing line source, as frequency response rises.

Now, whether Dr. Marks is correct in his beliefs, concerning the drawbacks of this design, is open to debate. The RS-1s operate as designed. However, they are not Mini-IRS speakers.

Click to expand...

Infinity! said:

...

The RS-1 and RS-1b's have crossovers at 150 Hz, 700 Hz, 3000 Hz and 8000 Hz.

The two woofer columns, each made up of 6 standard 8 inch woofers function below 150 Hz.

The top two, and bottom 4 EMIM's operate from 150 Hz to 700 Hz.

The 3rd EMIM down from the top operates from 700 Hz to 3000 Hz.

The top and bottom from tweeters operate from 3000 Hz to 8000 Hz.

The center front tweeter ( with the small CAP on the front ) actually acts as a Super Tweeter and only functions above 8000 Hz.

The rear tweeter operates from 3000 Hz on up."

WHAT DO YOU GUYS THINK??

Click to expand...

In comparison, in RS-II all three mids operate on 125-1500 Hz region and then the mid in the middle (next to the EMIT) fades out around 3 kHz, while the top and bottom mids crossover at around 1.5 kHz. So the whole geometry is designed to resemble a point-source as a function increasing frequency. And in comparison to RS-1b, the cross-over to single mid happens higher, at 1.5 kHz and not at 700 Hz.

line sources and point sources each have their own strengths and weaknesses. in a medium-sized or smaller room, the pseudo-point source of the RS1b should be technically superior to a full line source.