5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

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c.n.
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5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Tue Dec 21, 2010 4:07 pm

My main 5150 was working fine, then I didn't play it for a week or so, and when I played it again, it sounded dull. The amp has been sitting in the exact same spot, connected the same way, in my bedroom. No funny business.

After some fidgeting, I noticed that certain things were not working very well, if working at all.

First of all, the amp is much muddier and sounds kind of bad in comparison to before. A noticeable difference, even to people who are not musicians.

Now for more specifics...

Presence knob: makes no difference if maxed out or on 0. There is a slight change in sound; however, it is so microscopic, that you could consider it no change at all.

Resonance knob: no noticeable change no matter how you twist it.

Bass knob: Bass sounds kinda boomy on a regular setting of 6-7 (sounded fine before at these settings). Turning it off completely cuts the bass a little bit, but not as dramatically as it should.

Treble: This is the only way to get treble/presence out of the amp, but makes the sound more abrasive. Previously, I had it at 4, but now I have to turn it to 6 or so.

Mid knob: Don't really know how to describe this one, but it sounds different.

The moral of the story is that the entire EQ section and master presence/resonance controls are not operating properly.

What I've tried:

Unplugging and replugging FX loop plugs over and over
DeOxing FX loop jacks.
Unplugging FX loop completely (still same problem)

Does anyone have any idea what could be causing this? Please advise.

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WashburnTabu
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by WashburnTabu » Tue Dec 21, 2010 4:32 pm

Did you treat all of the other jacks the same way? Pre-amp out and power amp in jacks can cause the same sort problems, Although normaly it is low/no volume with dirty jacks. With the eq not working properly I would start checking/de-ox'ing the eq pots, if it has old school pots. Newer processor type amps like the vypyr use digital encoder knobs and they do not "get dirty" like a real analog potentiometer. The problem seems to be at or before the treble pot, like an open or short, grounding some of the high frequencies. The presence boosts treble, if it is doing nothing, then there are no high frequencies to boost. The resonance circuit is normaly a part of the power amp section to add or cut bass frequencies specific to that cab design. The resonance control should change something, unless there is so much bass now that cutting a db or two doesn't make a noticable change.
Try cleaning all jacks and spraying all pots and turning them from 0 to 10 many times.
If that doesn't do it, then wait for Enzo and others.
My name is WT, and I approve this opinion.

clutch71
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by clutch71 » Thu Dec 23, 2010 9:27 am

Did you try replacing the tube for V6? I believe this is assigned to the power section where the resonance and presence live. Not outside the realm of possibility that your power tubes are on their way out as well.
Peavey Amps: VTM 120, VTM 60 EL34 moddified, BRAVO Peavey Cabs: (2) 5150 Straight


KTB
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by KTB » Thu Dec 23, 2010 9:37 am

All of those symptoms are pointing to power tubes nearing the end especially treble loss.

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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by Giga » Thu Dec 23, 2010 10:26 am

KTB wrote:All of those symptoms are pointing to power tubes nearing the end especially treble loss.
This

Giga

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WashburnTabu
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by WashburnTabu » Thu Dec 23, 2010 10:47 am

#1 tube rule is to change power tubes when the tone changes. Keep a spare set, the can go out at any time.
My name is WT, and I approve this opinion.

c.n.
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Fri Dec 24, 2010 5:51 pm

Will try everything mentioned right after new years. Got a couple shows to play and a family avalanche at the moment!

Mega thanks for the suggestions.

Giga
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by Giga » Sun Dec 26, 2010 3:43 pm

Another suggestion: pull V4 and plug preamp-out directly into a knwon to be good poweramp. This will effectively shut the poweramp down while the preamp still works.

If this solves the equaliser probs you know the preamp is ok.

Now put V4 back in and use the amps poweramp.

It is very unlikely all powertubes are faulty, so if you pull 2 and try all combinations (number them with a marker to keep track) you should be able to determine which one is the culprit. (Use position 1 + 4 or position 2 + 3 for the powertubes and cut the impedance on the amp in half for this)

Good luck !

Giga

c.n.
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Wed Jan 12, 2011 1:50 pm

Uh oh... Just got to it (FINALLY) and... When I turn the amp on with the volume all the way down, I get some sound that usually comes through with the volume all the way off (even with my noise gate engaged in the fx loop which kinda bugs me).

When I turn the volume up on either channel, no additional volume/sound comes out.

Switched all the tubes with my 5150II and no change.

Put all the 5150II's tubes back into the 5150II and the 5150II works normally.

:( Looks like I'm in need of serious repairs. This kinda unfortunate because this particular amp is my favorite one.

Now I've had the amp repaired before for loss of output and degradation of sound... The tech just cleaned all the jacks and pots and replaced one little resistor...

I'm just afraid to take it back in to the same place. Even though they are a Peavey authorized repair joint, not a single person in there is a musician. Also, since they didn't repair it right (I guess) the first time and they are kinda expensive, I am even more reluctant to take the amp back into the same place.

Estilo
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by Estilo » Sun Jun 04, 2023 8:59 am

Bump and hello @c.n. did you manage to get it fixed? Mine seems to be exhibiting a number of symptoms you found - Very boomy bass, sound coming through even when volume is at 0. I live in Indonesia and there are no authorised service stores, and amp techs are self-taught. I'd be more comfortable directing them on what to do than getting them to diagnose.

c.n.
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Mon Jun 05, 2023 5:33 pm

Estilo wrote:
Sun Jun 04, 2023 8:59 am
Bump and hello @c.n. did you manage to get it fixed? Mine seems to be exhibiting a number of symptoms you found - Very boomy bass, sound coming through even when volume is at 0. I live in Indonesia and there are no authorised service stores, and amp techs are self-taught. I'd be more comfortable directing them on what to do than getting them to diagnose.
Yes! I cleaned the fx loop jacks more throughly this time!
I ran out of Deoxit and got a big can of CRC contact cleaner and worked a plug in an out 20x... Then used CRC lubricant which came in a small can but you don't need to use as much.

Deoxit was too expensive and the two CRC cans essentially do the same thing. Since you are in Indonesia and probably don't have the same products as the US, you could probably just use any electronics contact cleaner spray that isn't conductive.

Cleaning the Fx loop is pretty much tech support step #1 for these amps. Unless you've done it really well and the tubes don't look obviously roasted, there's almost no point in proceeding, because this is by far the highest failing thing in the amp. Cleaning them seems to fix 95%+ of all 5150 issues, NO MATTER HOW WEIRD AND UNRELATED THEY MIGHT SEEM!"

c.n.
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Mon Jun 05, 2023 5:40 pm

Estilo wrote:
Sun Jun 04, 2023 8:59 am
Bump and hello @c.n. did you manage to get it fixed? Mine seems to be exhibiting a number of symptoms you found - Very boomy bass, sound coming through even when volume is at 0. I live in Indonesia and there are no authorised service stores, and amp techs are self-taught. I'd be more comfortable directing them on what to do than getting them to diagnose.
The issue with volume coming through at zero seems to be an issue with the fx loop. It happens to both my 5150 block letters... Although some others have said it doesn't happen to theirs.

Im using all the original style, shuguang beijing foil getter 1wax7s in there which are very high gain, so that might be causing the bleed in the fx loop due to noise or something. The preamp tubes are not shielded from each other, so that might be why, but I'm not sure. The main issue that causes is when trying to play the amp at low volumes.. If you're running a 2+ on the Master, it probably does cause an issue because the sound bleed by then is so quiet..


But weird things with the sound at good volume and the eqs's not working and a bunch of other stuff I found were caused by the fx loop Jack's needing a good cleaning.

Estilo
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by Estilo » Sun Jul 09, 2023 9:29 pm

c.n. wrote:
Mon Jun 05, 2023 5:33 pm
Estilo wrote:
Sun Jun 04, 2023 8:59 am
Bump and hello @c.n. did you manage to get it fixed? Mine seems to be exhibiting a number of symptoms you found - Very boomy bass, sound coming through even when volume is at 0. I live in Indonesia and there are no authorised service stores, and amp techs are self-taught. I'd be more comfortable directing them on what to do than getting them to diagnose.
Yes! I cleaned the fx loop jacks more throughly this time!
I ran out of Deoxit and got a big can of CRC contact cleaner and worked a plug in an out 20x... Then used CRC lubricant which came in a small can but you don't need to use as much.

Deoxit was too expensive and the two CRC cans essentially do the same thing. Since you are in Indonesia and probably don't have the same products as the US, you could probably just use any electronics contact cleaner spray that isn't conductive.

Cleaning the Fx loop is pretty much tech support step #1 for these amps. Unless you've done it really well and the tubes don't look obviously roasted, there's almost no point in proceeding, because this is by far the highest failing thing in the amp. Cleaning them seems to fix 95%+ of all 5150 issues, NO MATTER HOW WEIRD AND UNRELATED THEY MIGHT SEEM!"
That's great to hear @c.n. Do you mean just using Deoxit, spraying it onto an instrument cable tip and just plugging in and out of the FX loop jacks many times? Didn't even have to open up the amp?

I'll add that my issue applies only to the Red channel, the Green works perfectly fine. Extremely boomy bass on the red channel such that the oomph is almost like an earthquake. I've also tried plugging a guitar straight into the return of the FX loop and it seems fine, so I thought it was a preamp issue.

c.n.
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Re: 5150 /6505 Problem - Doesn't work: Presence, Resonance, Lows

Post by c.n. » Thu Jul 13, 2023 9:20 am

It could be a preamp issue still, like tubes or something else, but cleaning FX loop Jack's ficlxes ALL SORTS of voodoo with these amps.

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