[BrunoB]

In 2005, the mid range LPAD of my 626 were set  between 10 and 12. Today, in 2009 , they are set at the maximum level and my speakers lack dynamic and speed.

What could explain the decrease of sensitivity?

Electric path:
I measured the resistance of the panels: 2.6 Ohms, the same value as when I first received them. OK.

Membrane:
Could the membrane become heavier?

Magnets:
Could it be possible, that over time, the neodymium magnets loose their strength?
 





Has anyone observed the same problem with their 626 or other models? I hope that I am the only one with this problem!


Thanks,

Bruno

[Pez]

I owned the 626Rs for many years and I NEVER had an issue with the dynamics getting worse or changing. Is it possible that your amp could be the culprit? Or maybe you've been to one too many rock concerts?

[Pez]

Or maybe this could be your issue.

 -home made ribbon foils for the tweeter, "Spaghetti ribbons", cleaned and silcleared contacts between ribbon and aluminium support

sounds like you've done A LOT of mods, which isn't necessarily a bad thing, but there you have it.

[opnly bafld]

Who knows with all the mods you have done to them over the years.
Are they in the same room and is your system 100% the same as it was four years ago?

FWIW I never had any problems with a pair of '02 RM40s and as far as I know the new owner has not had any problems with them. They have been in use for 7 years now.

Lin

[BrunoB]

Who knows with all the mods you have done to them over the years.
Are they in the same room and is your system 100% the same as it was four years ago?

No, not at all.

FWIW I never had any problems with a pair of '02 RM40s and as far as I know the new owner has not had any problems with them. They have been in use for 7 years now.

Lin

Thanks, that is good to know. Seems that I have to look elsewhere for the cause.

[BrunoB]

Or maybe this could be your issue.

-home made ribbon foils for the tweeter, "Spaghetti ribbons", cleaned and silcleared contacts between ribbon and aluminium support

sounds like you've done A LOT of mods, which isn't necessarily a bad thing, but there you have it.

Most of the modes were about the tweeter, not the mid panel.

[BrunoB]

This is a question for Brian:

what is the sensitivity of the mid panel?


Thanks,

Bruno

[Brian Cheney]

Nominal sensitivity is 88dB for the mid panel.

I have not experienced demagnetization of the panels over the years, and we've used them since 2001.  They exhibit a 2.5 dB rise in the 1 to 3kHz range which smoothes out over the years due to stretching of the diaphragm.  This is a good thing.  In the active version of the speaker we cut 2.16kHz by 2.9dB with a Q=1, which means the 1kHz to 3kHz range is reduced.  As the speaker ages less cut is required.

[Brax]

Who knows with all the mods you have done to them over the years.
Are they in the same room and is your system 100% the same as it was four years ago?

FWIW I never had any problems with a pair of '02 RM40s and as far as I know the new owner has not had any problems with them. They have been in use for 7 years now.

Lin

Your old 40's are sounding better then ever. I did most of the mods mentioned on this board. I really love these speakers!

[mjosef]

Nominal sensitivity is 88dB for the mid panel.

Wow...I always thought it was much higher, like 92-94dB. In my RM1s I usually have to roll back(cut) the mid panel vs the spiral tweeter by 2-3dB... Currently I have the spiral at full throttle(pot bypassed) with the mid pot at 1pm, which suits my taste. At this setting, SPL readings indicate that the tweeter is about 1.5 dB down from the mid panel (measured close range at 2"). 

[Brian Cheney]

Once again we run into differences in perceived performance vs measured.

The ear typically favors a bass boost below 80Hz in the 4 to 6 dB range and a somewhat smaller boost in trebles above 5 kHz.  The default factory control settings of 12 o'clock (-4dB from full output) for the mid panel and 1 o'clock for the treble (-3dB from full output, even though the FST is rated at 96dB and the spiral ribbon at 90dB) illustrate listener preferences noted and quantified by the research of Fletcher and Munson.