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> Peavey 6505+ Problem
wannabeaguitargo...
post Jul 11 2009, 02:17 PM
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Hey guys,

Question - So I was playing my amp yesterday and all of the sudden the volume decreased and wont turn up anymore. Both amp channels are working but at a significantly reduced volume. I tried changing out guitar cables. I checked it this morning too and still the same issue. Do you guys know what the problem might be? I bought the preamp brand new and only have had it for a month. Any clues? Is this related to the tubes?

Robert---
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Skalde
post Jul 11 2009, 02:25 PM
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I am not expert, but sounds like a tube problem.
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bladzerok
post Jul 11 2009, 02:28 PM
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it must be your power tubes that are going dead if you change them you should be good to go. although, you may need re biasing your amp(not sure if the 6505 plus need bias adjustement. to verify, just check if there is any bias adjustement switch on the amp). if it does need adjustement, i would recommend you to bring it to a guitar tech

hope it helps, and welcome to GMC smile.gif

Edit: does any one know if the Peavey valveking needs bias adjustement? thank you

This post has been edited by bladzerok: Jul 11 2009, 02:32 PM


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wannabeaguitargo...
post Jul 11 2009, 02:34 PM
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It does have a bias adjustment. I wasnt aware you needed to have it adjusted for changing out the power tubes though. hmmm.
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bladzerok
post Jul 11 2009, 02:38 PM
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QUOTE (wannabeaguitargod @ Jul 11 2009, 09:34 AM) *
It does have a bias adjustment. I wasnt aware you needed to have it adjusted for changing out the power tubes though. hmmm.


yea, as far as i know, the bias adjustement serve to have both tube operate on the same voltage, every tuboe is different, so it needs adjusting every time you change them


--------------------
My gears are:
guitars:
-simon and patrick accoustic guitar
-ovation accoustic guitar
-Ibanez S320 electric guitar
-Ibanez RG7321 electric guitar
amp:
-Peavey valveking 112
effects:
-Boss SD-1
-Dunlop crybaby from hell
-Boss GE-7 7-Band Equaliser
-Boss NS-2 Noise Supressor
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MickeM
post Jul 11 2009, 02:44 PM
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QUOTE (wannabeaguitargod @ Jul 11 2009, 03:17 PM) *
I bought the preamp brand new and only have had it for a month.

You mean you bought the amp new?
You still have warranty then so easiest would be to bring it to the shop, right?

The thing with new electrical items is that they will confess to their reliablility with a short period of time. If it runs the first few months it can keep going for 20 years. Issues will often show them selves early.

Peak inside to try and see if all valves are lit and none is too bright or too dim.
Try with another guitar, or try your guitar in another source just to rule it out as the cause of problem.
Try the cab (if it's not the combo) with another head to rule the cab out.

Then there's a possibilty to find out if it's the preamp or poweramp that's failing, but the also requires another amp with effects loop. Take the send signal (fx send/out in the loop consists of the preamp signal) and lead the cord into the other amp's fx return/in. Play through the 6506+ and if it sounds, the preamp work.
Then try the other way around, the second amps sent into the 6505+'s return and play through the other amp.


Otherwise, since it's new. Don't mess around too much opening it. It's the stores problem until the warranty runs out.

QUOTE (wannabeaguitargod @ Jul 11 2009, 03:34 PM) *
It does have a bias adjustment. I wasnt aware you needed to have it adjusted for changing out the power tubes though. hmmm.

Yes tubes come in different "voltages" (huh). It's wise to buy matching tubes, these are gathers since they all match eachothers voltages.
If you buy the exact same tubes (classed between 0-9 but now always branded) in the same class no bias would be needed. But most often you get what you get and need to bias.


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Ivan Milenkovic
post Jul 11 2009, 03:02 PM
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It's a tube issue probably. Factory tubes are often of low quality and they are there just to get amp working for the shop. In the future always swap the tubes as soon as you get the amp. Bad news is you will have to get new power tubes and bias them, good news is that you will probably experience better sound when cranked.
Changing tubes is piece of cake, pull old ones out and put new in, like game cartridges. Make sure the pins are in right positions, and that the amps was turned off for some time before you do it. Do not touch the tubes with bare hands, use gloves cause of the hand dirt and grease.
If you want to bias you will need three things checked:

1. Multimeter
2. Bias trim pot/pots (it's on the amp somewhere)
3. Bias test connections (on the amp, for connection with multimeter needles)

There will probably be 2 connections, that bias either one tube (if you have 2 power tubes) or 2 pair of tubes (if you have 4 of them)

Whole procedure goes like this:

- refer to peavey manual/customer support for 6505+ bias voltage values
- turn on the amp
- connect the multimeter cables to test connectors on the amp
- read the current
- take a screwdriver/coin and adjust trim the pots until you get the right amount of current
- connect to second test connectot
- get to same voltage values
- go back and forth again several times until you nail the equal value on both of them

This post has been edited by Ivan Milenkovic: Jul 11 2009, 03:04 PM


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wannabeaguitargo...
post Jul 11 2009, 07:56 PM
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Thanks for all the help guys!


Robert---
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Ivan Milenkovic
post Jul 11 2009, 11:59 PM
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Yes JJ's si what I can recommend as well. There is some useful info on www.eurotubes.com


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