Silverface Deluxe Reverb Hum
Moderators: pompeiisneaks, Colossal
Silverface Deluxe Reverb Hum
I've got another Silverface Deluxe Reverb on my bench. This one has a 240Hz hum when you turn the reverb knob up. Reverb works, everything sounds normal other than the annoying hum. Rolling tubes hasn't done anything, changing the reverb tank doesn't do anything, even having the reverb tank removed still produces the hum. Any suggestions? Thanks in advance.
Re: Silverface Deluxe Reverb Hum
I always recommend using a refrigerant spray first,..to see if any components or contacts react thermally. This is a quick way to find minor problems.
You might check the 22uf /25V cap on the return tube (V4A)
You might check the 22uf /25V cap on the return tube (V4A)
Re: Silverface Deluxe Reverb Hum
[quote="ampdoc1"]I always recommend using a refrigerant spray first,..to see if any components or contacts react thermally. This is a quick way to find minor problems.
Not trying to derail the thread, but this sounds interesting. Would appreciate more details.
Thanks
Mike
Not trying to derail the thread, but this sounds interesting. Would appreciate more details.
Thanks
Mike
Sunnydaze
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Stevem
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Re: Silverface Deluxe Reverb Hum
I have no idea what the hell he is posting about with checking the 25uf bypass cap, no less the freeze spray,man on man!
Anyway that being said we need to pin down where the hum is starting at, if you pull the 12at7 reverb transformer driver tube ( V3)does the hum quit, or do you have to pull V4 to get it to stop?
Anyway that being said we need to pin down where the hum is starting at, if you pull the 12at7 reverb transformer driver tube ( V3)does the hum quit, or do you have to pull V4 to get it to stop?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Leo_Gnardo
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Re: Silverface Deluxe Reverb Hum
Is it possible the tank's been reverse mounted with pickup (output) end under the power transformer?
Tank removed - leaves you with an open input to the return triode. Yes that would hum.
How far up on the reverb knob before hum gets objectionable? Usually you dial up 3 on a Fender, beyond that there's way too much reverb for anything. Past there, you don't need to go.
Keep in mind, wires to the reverb control are usually close to the wire bundle coming out of the hi voltage filter cap compartment (doghouse, bathtub), and that proximity can lead to hum pickup for reverb as well as vibrato channel controls. When a customer needs a super quiet amp I put a grounded copper foil shield between that hi voltage wire bundle and the row of pots & their connecting wires. Just did that on a 67 Bassman head, worked great, cut hum on the Normal channel to nothing.
I seriously doubt hosing down anything with freeze spray will reveal a problem. I use that stuff so rarely, and mostly on transistor gear, using the same can for 10 years.
Tank removed - leaves you with an open input to the return triode. Yes that would hum.
How far up on the reverb knob before hum gets objectionable? Usually you dial up 3 on a Fender, beyond that there's way too much reverb for anything. Past there, you don't need to go.
Keep in mind, wires to the reverb control are usually close to the wire bundle coming out of the hi voltage filter cap compartment (doghouse, bathtub), and that proximity can lead to hum pickup for reverb as well as vibrato channel controls. When a customer needs a super quiet amp I put a grounded copper foil shield between that hi voltage wire bundle and the row of pots & their connecting wires. Just did that on a 67 Bassman head, worked great, cut hum on the Normal channel to nothing.
I seriously doubt hosing down anything with freeze spray will reveal a problem. I use that stuff so rarely, and mostly on transistor gear, using the same can for 10 years.
down technical blind alleys . . .
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Stevem
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Re: Silverface Deluxe Reverb Hum
X2 on the sheilding!
Maybe like the Chours from that old Broadway song from the play Ok "the wind has been sweeping down the Plains"for too long!
Maybe like the Chours from that old Broadway song from the play Ok "the wind has been sweeping down the Plains"for too long!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Silverface Deluxe Reverb Hum
As V4 has its section in cascade with shared cathodes, a failing bypass cap can result in positive feedback, to the point of free running oscillation.I have no idea what the hell he is posting about with checking the 25uf bypass cap
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Re: Silverface Deluxe Reverb Hum
Just for sh*ts and giggles, change the cables. Then look at the lead dress around the tubes. Take out the 'send' tube. Hum? Look at the lead dress around the Reverb control. You'll get it. Move wiring around and listen if the hum gets better/worse.
You can lead a horticulture, but you can't make her think.
SORRY
My reply
1) I pulled up a fender DR schematic and referenced a connection adjoining the area mentioned that MIGHT be a problem and
2) suggested a freeze spray (computer cleaner sprays work well,..just up-end the can and spray each component) to eliminate or perhaps quickly find the problem. I've been using this "trick" to find thermal problems with resistors and capacitors for 35-40 years.
It appears my suggestions brought out the ass hole in a couple of the folks who responded to my suggestions. While the 1000+ guitar amps I've repaired do not make me the best on this forum,..... simple courtesy ought to be used if others are trying to help.
And to Stephen, us old Okies know you NYers don't have much in the way of manners, but If you'd like to come down, I'll give you a fast course for free, and also teach ya something about amps.
I don't care who you are, you don't know
everything.
adoc
1) I pulled up a fender DR schematic and referenced a connection adjoining the area mentioned that MIGHT be a problem and
2) suggested a freeze spray (computer cleaner sprays work well,..just up-end the can and spray each component) to eliminate or perhaps quickly find the problem. I've been using this "trick" to find thermal problems with resistors and capacitors for 35-40 years.
It appears my suggestions brought out the ass hole in a couple of the folks who responded to my suggestions. While the 1000+ guitar amps I've repaired do not make me the best on this forum,..... simple courtesy ought to be used if others are trying to help.
And to Stephen, us old Okies know you NYers don't have much in the way of manners, but If you'd like to come down, I'll give you a fast course for free, and also teach ya something about amps.
I don't care who you are, you don't know
everything.
adoc
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gui_tarzan
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Re: Silverface Deluxe Reverb Hum
Threats of attitude adjustments don't help, let's get back to solving the problem and actually help the guy like you guys have helped me so many times.
I recently worked on a Bandmaster Reverb that made some odd noises (squeals and such) and it ended up being a bad reverb cable. I swapped in a new cable and it eliminated the problem. Same with a Blues Deluxe, the end on the input cable at the reverb tank was loose when I tried it with a new tank. I bent the outside contacts on the cable connector in so it was tight on the RCA connector of the original tank and that also eliminated that issue.
Try that Bungle and report back please. I'm interested to know what is causing this.
I recently worked on a Bandmaster Reverb that made some odd noises (squeals and such) and it ended up being a bad reverb cable. I swapped in a new cable and it eliminated the problem. Same with a Blues Deluxe, the end on the input cable at the reverb tank was loose when I tried it with a new tank. I bent the outside contacts on the cable connector in so it was tight on the RCA connector of the original tank and that also eliminated that issue.
Try that Bungle and report back please. I'm interested to know what is causing this.
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."
Re: Silverface Deluxe Reverb Hum
I apologize to most of the viewers here, but one poster had not one, but two snide remarks about the advice I had given. I do not pretend to know it all, but I do have a lot of experience with amps, and there was nothing about my original suggestions that were out of the box.
a'doc
a'doc
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Stevem
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Re: Silverface Deluxe Reverb Hum
Sorry, I need to apologize to ampdoc as I was in a truly foul mod that day, one of those where things would have gone better had you not even got out of bed!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Silverface Deluxe Reverb Hum
Just another tool in the box, just don't spray hot tubes with it because they will explode. 
Tom
Don't let that smoke out!
Don't let that smoke out!
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JazzGuitarGimp
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Re: SORRY
I had to go back to see what I missed. I've stopoed reading his posts because of his insistant use of the exclamation mark, rather than the period to close every friggin sentence. Shouting everything you say smacks of a superiority complex, in my estimation.ampdoc1 wrote:My reply
And to Stephen, us old Okies know you NYers don't have much in the way of manners, but If you'd like to come down, I'll give you a fast course for free, and also teach ya something about amps.
I don't care who you are, you don't know
everything.
adoc
And Jim, i disagree: Sometimes a public 'spanking' is exactly what is needed to GZ34 a situation.
Oh crap, did I say all that outoud? I'm sorry, I thought I was just thinking it...
Lou Rossi Designs
Printed Circuit Design & Layout,
and Schematic Capture
Printed Circuit Design & Layout,
and Schematic Capture
Re: Silverface Deluxe Reverb Hum
Alright, sorry it's taken so long between my posts. Here is what I've tried...
1. Correction to my original post: Removing the reverb DOES make the problem go away, so obviously it's related to the reverb tank being connected.
2. Removing V3 (12AT7) does not make the problem go away.
3. Replacing the 25uF cap on the V4 cathode did nothing. Replacing the microphonic 3nF cap before the REVERB pot did nothing. Replacing the microphonic 2nF cap (not pictured in schematic) on the REVERB OUT jack did nothing.
4. I checked the power caps and one had a broken lead. Replaced that and the problem persisted.
The one thing I have not tried is replacing the reverb cable because I did not have one at the time. I will, however, try it the next time I am at my bench. It sounds like that's what a lot of people think is the issue. Also, the amp and reverb tank are out on my bench, so there shouldn't be any interference from the transformers.
As for the freeze spray, ampdoc1, I know exactly what you're talking about and I've also used this method effectively plenty of times. Not sure why you got so much flak for it but it seems like cooler heads have prevailed. For anyone still wondering, using a freeze spray will make components and solder contract, so if there is a broken solder joint that is causing intermittent or noise issues, freezing the suspected component/solder joint can reveal the issue.
1. Correction to my original post: Removing the reverb DOES make the problem go away, so obviously it's related to the reverb tank being connected.
2. Removing V3 (12AT7) does not make the problem go away.
3. Replacing the 25uF cap on the V4 cathode did nothing. Replacing the microphonic 3nF cap before the REVERB pot did nothing. Replacing the microphonic 2nF cap (not pictured in schematic) on the REVERB OUT jack did nothing.
4. I checked the power caps and one had a broken lead. Replaced that and the problem persisted.
The one thing I have not tried is replacing the reverb cable because I did not have one at the time. I will, however, try it the next time I am at my bench. It sounds like that's what a lot of people think is the issue. Also, the amp and reverb tank are out on my bench, so there shouldn't be any interference from the transformers.
As for the freeze spray, ampdoc1, I know exactly what you're talking about and I've also used this method effectively plenty of times. Not sure why you got so much flak for it but it seems like cooler heads have prevailed. For anyone still wondering, using a freeze spray will make components and solder contract, so if there is a broken solder joint that is causing intermittent or noise issues, freezing the suspected component/solder joint can reveal the issue.