Fender Deluxe Reverb metallic rattle

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fenderheavy
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Fender Deluxe Reverb metallic rattle

Post by fenderheavy » Mon Apr 05, 2021 4:27 pm

I’ve had this going on in my favorite amp for years. It’s a 1974 deluxe reverb.

On certain notes and it spits out this audible metallic rattling sound. Like say an F#. It will do this in both the lower and mid registers. It presents itself for the first half of the note played, then dies out quickly as the note starts to fade out. It’s not overly loud, but just enough to be annoying at “room” volume.

I just did the caps, new rectifier and power tube sockets, new output tube resistors, new plate resistors. New power tubes, new rectifier.
The amp sounds fantastic, except for the rattle that’s still there.

Its not channel / reverb specific. I can remove all preamp tubes except v1 and the phase inverter and it will still do it on the normal channel.

I’ve swapped in all sorts of different tubes from rectifier to preamp and it will still do it.

I’ve tried different speakers. Still does it.

I’ve taken the chassis out of the cab and run it to an independent speaker cab. Still does it.

Different physical room, same story.

Any insight on where this frequency specific noise could be originating? I’ve chopsticked the bag out of the amp, and cannot sort it out. Just thought someone else might’ve been down this road before and could help me get this thing right. Thanks!

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Re: Fender Deluxe Reverb metallic rattle

Post by muffonrat » Tue Apr 06, 2021 12:57 am

I had the same problem with a combo amp , in my case was the reverb tank.
When you took the chassis out of the cab and run it to an independent speaker cab was the reverb tank still connected?

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Re: Fender Deluxe Reverb metallic rattle

Post by fenderheavy » Tue Apr 06, 2021 7:55 am

I did not. I disconnected the tank, even left it in the other room :D

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Re: Fender Deluxe Reverb metallic rattle

Post by Beebe » Tue Apr 06, 2021 8:43 am

Is it coming out of the speaker, the speaker cabinet, or the amp? Is it the same with different guitars?
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Re: Fender Deluxe Reverb metallic rattle

Post by Beebe » Tue Apr 06, 2021 8:50 am

If it's coming out of the speaker, it points to a microphonic tube. But you changed them and the sockets. Maybe there are other components known to become microphonic??
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Re: Fender Deluxe Reverb metallic rattle

Post by øøøøøøø » Tue Apr 06, 2021 12:28 pm

Can you post a recording of the sound?

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Re: Fender Deluxe Reverb metallic rattle

Post by fenderheavy » Tue Apr 06, 2021 1:36 pm

Thank you for the responses.

I have tried different guitars, same result.

The sound does come out of the speaker.

I will try to get a recording up in the near future for analysis.

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Re: Fender Deluxe Reverb metallic rattle

Post by fenderheavy » Thu Apr 08, 2021 8:14 pm

https://soundcloud.app.goo.gl/m6Q1A5MnTCU4pCdQ8

Not the best recording , but if you listen it’s there.

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Re: Fender Deluxe Reverb metallic rattle

Post by sookwinder » Thu Apr 08, 2021 9:26 pm

I have that type of sound many times over the years... coming from the internals of the power valves.
Only would occur on certain bass notes.

Have you tried different valves?
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Re: Fender Deluxe Reverb metallic rattle

Post by hexes » Thu Apr 08, 2021 10:39 pm

you've tried all new tubes, you've replaced power tube sockets, you've replaced some components... have you done these modifications yourself?

If so, i'm guessing a good ole fashioned tap/chopstick test of every lead inside the amp (specifically the pins on ALL tube sockets), and every tube and tube socket hasn't provided any insight, correct? I found a loose tube socket in a friend's preamp (v2) section just two days ago that took wiggling tube a little aggressively in the socket to diagnose, but that usually presents as static-type noises. i'd take a second look at the power section too.

are there any tube clips, retainers, or preamp tube shields installed? is the bias in spec? all voltages testing within reason to the circuit?

the noise sounds mechanical to me over a phone speaker. does the note change if you lower the guitar volume a bit to hit the preamp a little softer?

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Re: Fender Deluxe Reverb metallic rattle

Post by sookwinder » Thu Apr 08, 2021 11:07 pm

The rattle I experienced was due to components inside the valve rattling.
In fact one time it happened during recording it sounded really good as the note faded away the rattle was there with the buzz of the amp.
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Re: Fender Deluxe Reverb metallic rattle

Post by øøøøøøø » Fri Apr 09, 2021 4:12 am

It really, really sounds like tube rattle.

Note that it's entirely possible to replace a tube with a brand new tube of the same type and still have it rattle.

Many newer tubes (and some older ones!) don't have adequate mechanical support inside (from mica spacers, et al) and the bits inside actually vibrate sympathetically. It's maddening.

Do you have a friend who could play that note over and over while, with a gloved hand, you firmly grasp and give a slight squeeze to each tube one at a time?

Sometimes a little pressure on the glass envelope is just enough to calm things down, and this could help you isolate the offending tube.

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Re: Fender Deluxe Reverb metallic rattle

Post by fenderheavy » Fri Apr 09, 2021 1:06 pm

Thank you for all the responses. I'll try to sort of shotgun all your questions best I can. Firstly- I'm glad you could hear it!

I agree that it sounds like a tube. Or a component that has gone microphonic. Or something physically rattling.

I usually only use this amp in band situations. At that volume, I could 99% ignore it. This noise has been present through the last 3 pairs of power tubes (RCAs, JJs, Hytrons). Like for many years. But COVID, playing at home at low volume, I realized that it was time to at least try to fix it. Caps were getting on 15 years, so why not do the work with eliminating the noise as a secondary goal. That is the reason I replaced the rectifier and power tubes and all the sockets. I'd hoped it would tighten that end of the amp up. I thought it was the rectifier as there was some loose filiment in the original tube.

It was not.

Tubes: I have tried different tubes. Currently installed NOS RCA 5u4 Rec, NOS JAN Phillips 6v6gt, NOS JAN Phillips 12at7 for PI, and a NOS JAN Phillips 12ax7 in V1. That's it. So NO tubes at all in V2-V5. No shields or clips installed. These 2 preamp tubes have been used in other amps with no noise. Preamp Tube sockets have been cleaned and tightened. Power amp tube sockets are new and tight.

I did do all the work myself. Bias is in spec (like 2mA spread - 19-21mA). No outrageous voltages in the power section that I recall. I have not run a voltage chart because the amp sounds excellent / as good as a fender can, except for this noise.

I've chopsticked every inch of this amp up and down and cannot locate it. Even bought a mechanics / auto stethoscope to try and sort out if it was the chassis , faceplate, or circuit board , etc. Admittedly this is all a little bit challenging when I have to also produce the offending note over and over.

I did the tube grab thing to stop vibration. No dice.

I tried a signal generator (via iphone) but that would not produce the rattle oddly enough.

I would like to get a friend to assist. I have one who is experienced with building amps. He is my first call once I get vax'd. A second pair of ears and hands standing next to me is what I need at this point.

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Re: Fender Deluxe Reverb metallic rattle

Post by øøøøøøø » Sun Apr 11, 2021 6:21 am

Okay, at risk of asking the obvious: You've verified that the symptom reproduces with a different guitar, yes?

That's one thing that I didn't see you specifically say you've ruled out.

I've experienced similar frustrating buzzes/rattles occurring via mechanical coupling issues on guitars that manifest through the amp, including but not limited to:

pickup mounting springs, vibrato system springs, loose braces on a hollow/archtop guitar, weird mechanical string coupling issues at nut and/or saddle, pickguard hardware, etc.

Since you've explicitly ruled out other likely sources (and since you couldn't get the issue to reproduce with a signal generator) I suppose it bears asking. Any time I've ever chased my tail like this, it's always been something obvious I didn't happen to think of.

Last year I had to pause a remote recording gig to have a loose brace repaired on a 1940s Gibson flat-top. When I took it in, it turned out that the guitar was fine, and I was confused...

Until I realized that on a multi-stand across the room, an ES-330 was just barely touching the back of a seldom-played nylon string, rattling sympathetically on certain notes. I've got a few years in the game, but still missed that one!

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Re: Fender Deluxe Reverb metallic rattle

Post by sookwinder » Sun Apr 11, 2021 7:37 am

Did you swap out the rectifier valve, usually a GZ34 on a DR ?
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