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View Full Version : Possible Problem with Mesa Dual Rectifier 100W Head (3 Channel)


zewsk
09-01-2009, 08:19 AM
I just bought a used Mesa Dual Rectifier 100W (3 Channel) head from Guitar Center. I've had it for about three days and I think I've got a problem with it. I'm using the head with a Marshall 1960A 4x12 cab. I'm running it stereo to the cab with 2x8 Ohm inputs.

When I turn on the head, I usually leave it in standby mode for a few minutes to let it warm up. When I take it out of standby and try to use any of the three channels, I have to crank the volume to hear any kind of sound. The amp isn't giving me any kind of high gain sound at all - just a lot of hum/hiss and regular old guitar sound. No matter how much I crank the gain or fiddle with the EQ, I can't get the sound to change.

I played the amp the day I got it and the day after with no problems. The day after I got it, I did have to cranked to about half way on the volume (I had it up pretty loud) but everything was working. No problems at all.

Any ideas of what could be causing the amp to act funny now?

RussB
09-01-2009, 04:25 PM
First off the recto isn't a stereo output amp, so you're just running 2 cables in the cab. Are you using speaker cables and not guitar cables?

Try just running the cab as a 4-12 in either 4 or 16 ohm (whatever the recto can be switched to)

Next, try a jumper cable (guitar cable) in the effects loop, send to return

make sure you have the master volume up as well ;)

SgtThump
09-01-2009, 04:58 PM
...I have to crank the volume to hear any kind of sound. The amp isn't giving me any kind of high gain sound at all - just a lot of hum/hiss and regular old guitar sound. No matter how much I crank the gain or fiddle with the EQ, I can't get the sound to change...

Anytime that happens on my own amps, I always suspect a preamp tube and am usually right. I'd say there's an 80% chance that's what it is.

The good news is that Guitar Center DOES take back used gear in their 30 day window, so you have alot of time to troubleshoot it. Try replacing the preamp tube in the first few slots and see if that fixes it. If it doesn't and you don't feel like screwing with it anymore, return the sucker!

never-enough
09-01-2009, 05:03 PM
yes, if you are plugging into two 8ohm inputs on the cab you should be using the two 4 ohm outputs on the amp.

it does sound like a preamp tube though

zewsk
09-01-2009, 07:14 PM
Thanks for the replies, guys. I ended up just taking it back to Guitar Center to have them check it out. They discovered that 4 of the 5 preamp tubes weren't glowing and offered to replace them. Interestingly enough, the 5th one failed after the first 4 were replaced. So, they ended up replacing the 5th one for me, too. So, I've got 5 new preamp tubes and the amp is working beautifully, now.

sleepingtiger
09-01-2009, 07:15 PM
Sounds like the loop setting or maybe dirty loop jacks.

Tony

Squigglefunk
09-01-2009, 07:23 PM
Thanks for the replies, guys. I ended up just taking it back to Guitar Center to have them check it out. They discovered that 4 of the 5 preamp tubes weren't glowing and offered to replace them. Interestingly enough, the 5th one failed after the first 4 were replaced. So, they ended up replacing the 5th one for me, too. So, I've got 5 new preamp tubes and the amp is working beautifully, now.

I really doubt 4/5 preamp tubes went bad all at once...

looking for glowing tubes is not always the best way to see if they're working right. Some tubes don't glow much at all. More likely only one was bad and you just got all new tubes for free. Either way good ending I suppose!

SBlue
09-01-2009, 08:10 PM
I just bought a used Mesa Dual Rectifier 100W (3 Channel) head from Guitar Center. I've had it for about three days and I think I've got a problem with it. I'm using the head with a Marshall 1960A 4x12 cab. I'm running it stereo to the cab with 2x8 Ohm inputs.

When I turn on the head, I usually leave it in standby mode for a few minutes to let it warm up. When I take it out of standby and try to use any of the three channels, I have to crank the volume to hear any kind of sound. The amp isn't giving me any kind of high gain sound at all - just a lot of hum/hiss and regular old guitar sound. No matter how much I crank the gain or fiddle with the EQ, I can't get the sound to change.

I played the amp the day I got it and the day after with no problems. The day after I got it, I did have to cranked to about half way on the volume (I had it up pretty loud) but everything was working. No problems at all.

Any ideas of what could be causing the amp to act funny now?

I know it sound stupid, but read the manual. In case you don't have it, it can be downloaded online.
The Three Channel Dual Rectifier have way too many knobs, ins & outs, volumes, masters and slaves, loop setup, etc... so you will need to read the manual to use that amp properly. There are different ways to add or remove volume insert point on the amp(in and out of the loop, and output on front panel).
I have a lot of different tube amps for a long time, and never thought I needed to use a manual 'till I got 3 channel DR.
Trust me, download the manual and enjoy the endless setup possibilities.
SBlue