[sdiy] Buzzing reverb

[Roy J. Tellason]

On Saturday 16 April 2005 10:06 pm, Steve Begin wrote:
> It seems like if i move the tank somewhere else or even turn it around
> inside the enclosure the buzzing is reduced drastically.
> I got it really cheap but it's been buzzy right from the start, and it
> would seem kind of crazy if it was just built this way.
> Is there anything that could cause a spring reverb to become more sensitive
> to noise from the power transformer?  (it looks like it's probably over 20
> years old)

A busted ground connection,  sound like.

> If I can't find any other solution I'll probably just mount the tank
> externally, but I'm curious as to how it got this way.

Early reverb tanks had no strain relief on the wires going from the in/out 
jacks to the coils.  Bounce them around enough and you get a broken wire. 
Later tanks had a dab of glue or a small metal bit or something to take the 
stress off those soldered connections...

> steve
>
> ----- Original Message -----
> From: "Bob Weigel" <sounddoctorin at imt.net>
> To: "Steve Begin" <trypannon at hotmail.com>
> Sent: Saturday, April 16, 2005 7:52 PM
> Subject: Re: [sdiy] Buzzing reverb
>
> > sure.  That means the tank is probably ok..barring any broken springs
> > inside. Possibly then the problem is in the amp that picks up the signal
> > from it. -Bob
> >
> > Steve Begin wrote:
> >> Forgive me for asking, but how would you measure these impedances?  if i
> >> have the spring tank unplugged and i measure across the rca connector i
> >> get 200 ohms on both input and output.  Does this mean anything?
> >> -steve
> >>
> >>
> >> ----- Original Message ----- From: "Bob Weigel" <sounddoctorin at imt.net>
> >> To: <synth-diy at dropmix.xs4all.nl>
> >> Sent: Friday, April 15, 2005 9:59 PM
> >> Subject: Re: [sdiy] Buzzing reverb
> >>
> >>> Yeah that's what I tried to say..not sure if my mail got through.
> >>> Reverb cans OFTEN have problems with coil connections to leads (they
> >>> fail in mexico to use strip-x or equiv to pull the enamel off the wires
> >>> it appears..and they just solder and say a prayer.)  check again the
> >>> impedences to the can. Input depending on can should be between almost
> >>> nothing and a couple hundred ohms.  Output 20 to maybe 800. Most common
> >>> ones I see in that kind of thing measure a DC impedence of 57 ohms on
> >>> the in and 200 or thereabouts on the out.  If no connect on output
> >>> you'll be amplifying an antenna. -Bob
> >>>
> >>> harrybissell wrote:
> >>>> oooh... my bad
> >>>>
> >>>> I missed a clue.  If the Parametric EQ works without hum, but he
> >>>> reverb DOES hum... its is very likely NOT a cap in the power supply
> >>>> !!! Broken
> >>>> wire, or EMI.  Or it could be a bad connection at, or insdie the
> >>>> reverb tank itself. They usually use RCA connectors, famous for having
> >>>> corrosion
> >>>> etc...
> >>>>
> >>>> H^) harry
> >>>>
> >>>> jays at aracnet.com wrote:
> >>>>> You haven't moved it next to something that has a lot of EMI have
> >>>>> you?
> >>>>>
> >>>>> Reverbs are great for picking up AC hum from computer monitors and
> >>>>> other units power supplies.
> >>>>>
> >>>>> Like Harry said, either bad caps or bad ground would be my guess
> >>>>> after EMI. Usually linear power supplies aren't that bad to deal
> >>>>> with.
> >>>>>
> >>>>> Jay S.
> >>>>>
> >>>>> Steve Begin wrote:
> >>>>>> I have an Intersound PRV-1 Spring Reverb / Parametric EQ, and when
> >>>>>> the reve=
> >>>>>> rb section is switched on, there's a really loud buzzing sound added
> >>>>>> to the=
> >>>>>> output.
> >>>>>> It does this regardless of whether or not there's an input present,
> >>>>>> and the=
> >>>>>> buzz would appear to be 60Hz.
> >>>>>>
> >>>>>> Would this mean it's likely one of the filter caps somewhere is
> >>>>>> dead? If s=
> >>>>>> o is there anything anybody can tell me about how I should go about
> >>>>>> locatin=
> >>>>>> g the offending capacitor?
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Steve=