Comments on modification of Klipsch RP-600m speakers
Aug 16, 2021 8:16:34 GMT -5
cheapthryl, dsonyay, and 1 more like this
Post by Boomzilla on Aug 16, 2021 8:16:34 GMT -5
I got a kit from GR-Research for the modification of the Klipsch RP-600M speakers. The kit consists of three components:
1. proprietary "No-Res" self-stick foam for lining the inside of the speaker cabinet
2. copper tube connectors for one pair of speaker wires
3. replacement crossover components
Of these options, the only one I used was the "No-Res" foam. This had significant impact on the speakers' sound as follows:
1. The speaker box sounds significantly less live when rapped with your knuckles
2. The speakers' treble sounds significantly higher in amplitude than without the No-Res (I attribute this to less box vibration in the lower frequencies)
3. The midrange sounds sucked out (probably due to the treble emphasis)
Note that the speakers had a "lively" treble presentation even before modification, and that characteristic is exacerbated significantly by the addition of the No-Res material.
Options: I had initially thought to add a series resistor to the tweeter terminals to reduce the treble output. I alternately considered adding an L-pad to be able to adjust the treble. But in the end, I used digital signal processing (DSP) in my Roon music server program instead. I implemented a -1.5 decibel shelf filter at 2,000 Hz. This reduced all frequencies above 2,000 Hz. by 1.5 decibels. The result: WOW! The speakers immediately sounded far more open, more balanced, and more articulate in the midrange. They still sounded slightly bright, though, so I went back and increased the shelf filter reduction to 1.7 decibels and changed the shelving frequency to 2,250 Hz. Now these bookshelf speakers sound like MUCH larger speakers, and their "speed" is amazing without any treble emphasis.
The modified speakers (with DSP correction) are the very best bookshelf speakers I've heard in my room. I'd recommend the No-Res material to anyone wanting to do away with speaker box resonances. It works.
Boomzilla
1. proprietary "No-Res" self-stick foam for lining the inside of the speaker cabinet
2. copper tube connectors for one pair of speaker wires
3. replacement crossover components
Of these options, the only one I used was the "No-Res" foam. This had significant impact on the speakers' sound as follows:
1. The speaker box sounds significantly less live when rapped with your knuckles
2. The speakers' treble sounds significantly higher in amplitude than without the No-Res (I attribute this to less box vibration in the lower frequencies)
3. The midrange sounds sucked out (probably due to the treble emphasis)
Note that the speakers had a "lively" treble presentation even before modification, and that characteristic is exacerbated significantly by the addition of the No-Res material.
Options: I had initially thought to add a series resistor to the tweeter terminals to reduce the treble output. I alternately considered adding an L-pad to be able to adjust the treble. But in the end, I used digital signal processing (DSP) in my Roon music server program instead. I implemented a -1.5 decibel shelf filter at 2,000 Hz. This reduced all frequencies above 2,000 Hz. by 1.5 decibels. The result: WOW! The speakers immediately sounded far more open, more balanced, and more articulate in the midrange. They still sounded slightly bright, though, so I went back and increased the shelf filter reduction to 1.7 decibels and changed the shelving frequency to 2,250 Hz. Now these bookshelf speakers sound like MUCH larger speakers, and their "speed" is amazing without any treble emphasis.
The modified speakers (with DSP correction) are the very best bookshelf speakers I've heard in my room. I'd recommend the No-Res material to anyone wanting to do away with speaker box resonances. It works.
Boomzilla
