Can you find it?

[Andre LaFosse <altruist@shoko.calarts.edu>]

After typing up the following description of my infamous anomaly for Kim, 
I thought I'd post it here to see if any other users can detect it.

---------- Forwarded message ----------
Date: Thu, 30 Oct 1997 23:11:33 -0800 (PST)
From: Andre LaFosse <altruist@shoko.calarts.edu>
To: Kim Flint <kflint@annihilist.com>

> Boy Andre, I thought I had a tendancy to be too verbose! I am but an
> amateur before you....:-)

That's what I get for being an ex-English major.  Or maybe it's all the 
"intelligent" british dance music...

> In my units, I can barely discern such a noise with the mix pot in the
> middle. But that's with the plex volumes up and into a 140watt amp 
>cranked
> all the way up! The noise floor is very loud at that point, and I'm only
> just hearing any digital hash noise. It seems like you are hearing
> something much more present and noticeable than that. Would that seem 
>right?

Here's the recipe for the Andre LaFosse Noise Special (updated for its 1 
year anniversary):

-- Record a note with the guitar fading in a single note.  Start the 
recording before fading the note in, and fade the note in quite slowly.  
Let the note die down to almost silence before closing the loop.  

-- The telltale noise will correspond to a flickering on the Feedback LED
(which I mistakenly referred to as the Input LED in my cover note to
Oberheim -- mea culpa indeed).  When the LED for feedback flickers at the
beginning or end of the note, or if it sustains below a threshold loud 
enough to cause the LED to glow solidly, the noise rears its head. 

-- Pressing mute leaves the noise intact and audible at the same level as 
if there's a loop going on.  Since the feedback LED flickers even in 
MUTE, the noise may be easier to identify in this way.

-- Once the loop is overdubbed or built up to the point where the overall 
level of the loop never drops below a certain threshold, the noise 
disappears.

-- Turning the MIX control to either extreme eliminates the noise.

-- The noise exists in both record and overdub mode, and is subject to 
all of the conditions above, so it has nothing to do with the A/D 
converters at the front of the unit.

-- There was ONE occasion after I initially discovered the noise in July 
when it was not present: I had turned on the Echoplex and was testing it 
without having turned on a lamp nearby.  I did not hear the noise.  I 
then turned the lamp on and the noise was instantly there.  I brought the 
Echoplex into another room to test it immediately thereafter, and the 
noise was still there, as it has been on every occasion afterwards.  
(Needless to say, the lamp was not present during the subsequent tests).

-- This is a fairly subtle noise.  The thing that made me suspect that it
was a malfunction was a note I recall getting from you which read, "If
you're seeing a flickering light on the LED in conjunction with the sound,
there's definitely a higher-than-normal amount of noise going on" (this is
a paraphrase).  Owing to the scarcity of available Echoplexes, I wasn't
able to test another unit to determine if the anomaly was there in other 
models.

> One question, on the top piece of your chassis, if you take it off and 
>look
> at the underside, you should see a piece of foam tape along the front. 
>This
> is there to keep the flat cables from pressing against the top piece of
> metal. Is that there in your unit? If not, the noise would likely be
> coupling in throught the chassis, which is why we put the tape there. If
> you don't see any tape there, you should be able to get some at a
> stationary or hardware store or someplace. Put a strip of it along the
> front of the top piece, where it looks like the flat cables will press up
> on it. That could make a big difference.

I recall your recommending this; there is no tape on the top panel, but 
this noise is just as audible when the top is completely removed from the 
unit.  If it's there when the flat cables are sitting out in the open 
air, then I don't see how it could be attributable to contact with the 
top panel.

> seems like it should be more subtle than you seem to be experiencing.
> Without hearing it and without seeing the set up where you have it, It is
> very difficult for me to tell. I assume we're talking about a noise 
>that's
> readily obvious in a normal listening environment? And you never noticed 
>it
> in that past right? It just appeared one day?

I first started noticing this over the summer, and running the Echoplex
through a Roland VS-880 unit.  My first inclination was to suspect that it
had not always been there and that I would have noticed it had it been
there all along, but my mistaken assumption about the noise gate issue
during last year's episode (some sense of Deja Vu, huh?) proves that this
may not be the case. 

I also observed this when plugging the unit straight into a guitar amp,
and into a friend's stereo system on Tuesday night.  However, my friend
(who is a musician of an extremely high order) had to have me specifically
point out the sound before he noticed it. 

Given the fact that the only original part of my Echoplex currently
sitting next to me is the chassis, and given that the noise exists even
when the top part of that chassis is removed, I'm more and more inclined
to think that this noise is an inherent element of the instrument,
something which is subtle enough to have evaded detection until this past
summer.  Now that I've detailed the anomaly in such... detail, I think
I'll forward a copy of this to the digest to see if anyone else can detect
this. 

As always, Kim, your patience and dedication amazes me.  Thanks for 
maintaining interest.

--Andre