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Just Purchased Infinity RS2B / RSIIb owned RS 2.5

FYI Infinity Fans:
I have lusted after some RS2bs for 20 years after loveing my 2.5s. I thought the 2bs would fill in the middle and keep all of the strengths of the 2.5s. In reading the manual, I was unaware that the 2bs had a bass equilizer (not crossover) that was NOT optional. The bass equilizer has been lost. I hooked up my VTL compact 100s with several preamps & the sound was mud in the bass and boring in the emims/emits. One of the emits is even covered 50 percent, the top one in the front. These 2bs sound like monster cable . . . go figure. Monster cable was used in the speakers. Also, it turns out that ONLY the middle emim is hooked to the midrange control. The middle emim is the only one that sounds like the emims in the 2.5...they are running full out. The top and bottom emim are subdued and they are trying to mimic a good dome midrange....yes the lower vocals are better but who cares?? I have lost the magic of the emims. I have had some Infinity Sigmas in my room and one super emim did a better job than these three emims. Last night I hooked up a couple of transitor amps and the sound was MUCH improved... remember what older monster cable did to good solid state stuff? in the 80s. I guess I'm going to stay with threshold but I own several good tube amps that I love to hear the imaging etc etc. I might be nuts but the improvement I have gained with Kimber Kable 4TC and Audioquest jaguar interconects is lost in the old monster cable wire?? I am probably being to hard on these speakers, but I remember a german saying the 4.5s were the best of that vintage. How are the emims controled in the RS1bs?? are they all hooked to the crossover controls?? To be continued. Thanks for reading. Larry
apfdirtdoctor

Showing 3 responses by ait

ait
480 posts
 
Ladycharnet, the EQ box does more than boost below 100Hz. I have studied mine extensively and also modded it extensively, and here are the facts:

1) bass gain adjusts bass boost below 100Hz, especially from 50Hz down
2) contour adjusts the slope downward below 2000Hz

Without both of those adjustments the RSIIbs will not be flat in response. The non-EQed speaker has a rising response below 2kHz that peaks at 50Hz and then falls like a rock - the contour adjustment knocks down the rise and the bass gain fills in the area below 50Hz.

Here is my in-room frequency response without the EQ:

RSIIb no EQ

and here it is with the EQ:

RSIIb with EQ

Here is a plot of the frequency response of the EQ unit itself when fed a pink noise signal from 20-20kHz:

EQ Response

If you have another EQ unit that allows you to plot the in-room response you may be able to come up with settings that approximate the stock unit.
ait
480 posts
 
Well I un-watered-down my unit (I guess that would be "concentrating" it). Mine now has all metal foil and metal film resistors, high speed OPA827 opamps, and high quality PP, PS and copper foil/PIO caps. I also moved the power supply and the output circuits off the main EQ board to reduce interference, upgraded the capacitor filter to a CRC, added Bybee Music Rails DC power conditioners to both the + and - power supplies, inserted a TI-shield shield between the noisy power supply section and the rest of the unit, and built a directly DC-coupled output curcuit using very low DC-offset opamps to replace the stock MOSFETs. I also replaced a couple of the resistors with cermet pots so that I could tailor the response curves to be different for each channel to suit my room.

Here's what the inside of the unit looks like now:

Modified LF EQ Unit
ait
480 posts
 
If you really want to go crazy, check out the new EMIM ribbons offered by Apogee Acoustics. They fit in the standard EMIM shell and are a HUGE upgrade in sound quality over the originals.

Graz at Apogee makes them in batches of 90, about once or twice per year. You have to get on the list and when he has enough pre-orders he makes a batch. The build quality is stellar. Here's a link to his Infinity forum:

New EMIM Ribbons

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