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Studio Hums 'cause it doesn't know the words...
was a studio in Coraopolis, PA that I was sort of involved in. A local
band sort of rented it from a local business guy and he ended up with a
partner - Bill. Long story short, a lot of political upheaval and
But I was doing some tech work there They had an old
Amek 2500 console and a vintage A80 Studer. I recall Blues Travelers
and Hootie & the Blowfish being there two different times when I was doing some
repairs. Hootie was cool, But I recall Blues Travelers kicking
everyone out for their rehearsal.
"You too hippie - gotta go!"
as I had the master module out trying to figure out why the
logic rail went dead. "Ok cool...." I stated as I was
putting my tools and test gear away. While pulling my tool cart out of
the control room I mentioned, "Good luck - BTW - the console's dead..."
A quick aside with the head Blues dude and his manager - "OK you can stay..." "Really?" I thought. "Gee, thanks..."
as you can see in the pic's the equipment was long in the tooth,
even back in the early 90's. That's my first born when he was about a
year old at the Studer and old Amek...
recall that with the old gear, any guitar or bass brought into either
the main studio or the upstairs MIDI-room was affected by an atrocious
In fact, the old A80 MKii Studer 24tk would hum on repro during
mixdown unless you moved it to a certain angle and adjusted the head
shield to a 45 degree angle. I didn't know at the time what caused it,
we guessed it was something to do with the large power lines located
along the building.
I also had recently proto-typed a bass
guitar preamp and installed it in one of my basses, an old BC Rich
Warlock that used to pick up everything from hum to radio stations near
my house. After installing my prototype, I took it to the studio, which
we were refitting with a new Studer A827 and AMEK Rembrandt console. To
the amazement of the entire staff, I was able to turn the amp to max
with no hum or buzz. The amp was turned up so far that just touching my
A string with my left hand caused the amp to go into
clipping/protection. I was able to walk around the entire main room
with no change in the noise floor.
This is the New Stuff ...
So they suffer a lightning hit and I get called in. The partner of the
owner wants to just replace the gear. They get hold of a new Amek
Rembrandt with Neve EQ; he was working for Harmon/Amek at the time -
got invited to meet him at AES - but that's another story. They also
bought a new Studer A827 - the last of the multitrack analog decks that
Studer would ever make.
Here's some pic of the new design I did. Made it into Mix magazine I'm told...
installing the bulk of the wiring audio , and having the local
electrical contractor finish the new service entrance (3PH 208
wye), and overseeing the room refit I had to leave Pittsburgh due
to my day job ( I was the founder a communication electronics
firm - my lab: http://www.ajawamnet.com ).
got a call a few weeks later. Seems that when Studer/Revox finally came
to the studio to commission the new 24-track, they encountered more hum
and buzz than the old A80 had. After repeated attempts to get Studer to
help they told the owner, Bill, that he should have done an EMF survey
before building the studio there. He reminded them that it was an
existing facility but their only offer was to mu-metal the head stack
cover and repro head wiring.
When Bill called me ( I had since
moved) , it was so bad I heard the hum over the phone. He had the guys
there from Duquesne Light (the local utility) and AMEK. I asked him if
it was only in repro and he confirmed my theory; there was a serious
EMF field being impressed across the room and the new 24-tracks repro
head stack. I told him to try and isolate the old building power from
the new studio power service we'd just installed.
Well, Duq Lite
brought in a mobile generator along with the VP of Engineering. Even
with all the power to the building cut at the utility pole and just the
console, monitor amps and Studer on, there was still an atrocious
hum - just in repro mode. The guys from Duq Light were stumped. Their
milligauss meter showed that the field seemed to emanate from the floor
in front of the console. They couldn't understand how, since all of the
power for the building was off. They gave up.
Later that day
Bill calls to tell me what happened. I told him to check and see if
there was a ground wire in the basement, tying the old service to the
cold water pipes which came in from the other side of the
building. Poor Bill was so distraught he was ready to do
anything. In fact he'd just bought $3k worth of mu-metal sheets in a
desperate attempt to line the ceiling in the basement.
went downstairs, told me that yes indeed there was a bare copper wire
going between the old service and the pipe near the water meter. It was
traveling across the beam, right about where the Duq Light guys
So I’m on the phone, can easily hear the hum in
the background. I told him to cut it at the cold water bond point; when
he did, I could hear that the hum had changed harmonic content
but was still there. When he got back on the phone he
mentioned there was a definite difference in the hum, and that when he
cut it, it melted the dikes.
I hung up. Within the hour, Bill called me all excited. No more hum.
said he went down after talking with me about 8:30PM, shut off the
water before the meter, and with rubber gloves, grabbed a hacksaw and
cut the pipe right after the meter and inserted a plastic section of
pipe. He stated that when he finished the first cut, the hack saw
blade melted to the pipe coming out of the water meter. I asked him to
grab a DVM from the shop and see what the voltage was across the
plastic pipe. About 60-80VAC... I told him he’d better call the power
When the VP of Duquesne Light came back he
again measured the floor in front of the console – no more EMF. As they
were inside one of the DL techs came in with a stick mounted version of
the milligauss meter and mentioned that the sidewalk outside was now
showing an increase in EMI. He also mentioned that as he was outside, a
man approached from the VFW across the street and mentioned, " I saw
your Duquesne Light trucks and have a question - last night about 9PM
all my lights in the hall during bingo got real dim..."
the building across the street had an open neutral, caused by a
lightning hit, and their neutral current was actually going down
the bonded ground in their box, across the street to his studio via
the bonded pipe and finding its way to his grounding system via
the building metal. These buildings were older and it was typical to
bond the neutral and safety in the
mains panels. The VP confirmed this by talking the gauss meter out on to the
sidewalk where the water service came in.
Some of the strangest shit I've ever had to troubleshoot...
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