I very recently purchased a Sanders Magtech amplifier to
feed my Magnepan 3.7i speakers. I have a
30 day trial period so I have been diligent in my efforts to “exercise” the
Magtech to see if it fits my needs.
I have lamented the lack of useful dB meters or even dB LEDs
on the front of the Magtech. This may
seem childish until one has a problem. Twice
in two days it seems as if one (right hand side) speaker cut out.
My hand held dBa meter tells me I was always under 90 dBa and my Rotel RC-1590
pre-amp tells me it was set at 70% of full power; so I will argue that I was not
hammering on it.
I’ll turn the pre-amp down to 40%, take a short break, return
and when I do both speakers are working perfectly.
It could be a source problem, a pre-amp problem, a power amp problem or a
speaker problem.
Tuesday morning I called Josh at Sanders and his idea was
that sometimes the power amplifier fuses do not travel well. "So remove and replace and the problem may go
away." Maybe circuit breakers reset, in my experience AGC glass fuses don’t heal
on their own.
When I mentioned that some indicators might be helpful he
mentioned that Sanders internally uses “American Audio LED dB Level Displays ”
($80 on Amazon) which, I am advised) are sonically transparent, I could place
one before and another after the Magtech. So I purchased two.
I could also put an ohm meter across every RCA cable, search
for an intermittent open cable? No one
was anywhere the cables when this happened twice. I've purchased "audiophile" RCA cables that were bad out of the box.
My Rotel pre amp lacks the ability to swap L&R channel
output. In general making an equipment configuration
more complex, or adding 3rd rate auxiliary junk, is not how one best
diagnoses complex problems. I have mixed
feelings about this approach.
I own a Samsung Galaxy S9+ phone. I found a RTA app for my phone named “Audizr
Pro” which cost me 99 cents and so far I think it was money well spent. When my furnace fan kicks on I get a 260 Hz
noise that is -70 dBa; it can detect it with the room other wise silent. I also have a very large Levoit air Purifier in
an adjacent room that the Audizr can detect in an otherwise silent room. There may be other RTA apps for android devices
if you have some experience I would like to benefit from your experience.
I own an inexpensive “American Recorder Technologies Sound
Pressure Level Meter” which cost me $50 five years ago and is still on the
original batteries. I would argue that
it is not OSHA calibrated but it is better than nothing, or better than
guessing. Without it I would not know
that I seldom have 90 dBa listening levels, I would have guessed I was above
100 dBa.
Other than educated ears, what instruments do you use in
your listening room? I had some very inexpensive
thermometers I used to position on the shelf beside or on top of my power amplifier.
