Blew my PRS 1x12

[TRJC24PRS]

So yesterday I was playing at a friends house and we played for only about an hour, and my amp blew. So I have very limited knowledge on amplifiers and cabs so I will come to you guys. Basically it makes a loud hissing on both channels, and if i turn it up any louder it will stay at the same volume. What should I do.

 

[Tone-y]

Change the valves?

 

[TRJC24PRS]

Change the valves?

Would that be whats causing the noises? I was thinking it was the cabinet itself

 

[RickP]

There are a myriad of things that can cause issues, from your cord, to a bad solder joint, to a bad tube in the preamp or power amp, to pretty much anything between the input and speaker failing.

Best to start with what amp we're discussing, what you've checked and those results. Maybe we can help from there.

 

[TRJC24PRS]

There are a myriad of things that can cause issues, from your cord, to a bad solder joint, to a bad tube in the preamp or power amp, to pretty much anything between the input and speaker failing.

Best to start with what amp we're discussing, what you've checked and those results. Maybe we can help from there.

Its an MT15, Im not quite sure if its anything about the pre amp but i have replaced a pre amp tube in it already and my cable isnt faulty any.

 

[RickP]

Its an MT15, Im not quite sure if its anything about the pre amp but i have replaced a pre amp tube in it already and my cable isnt faulty any.

Ok, we’ll go from there.

When the amp is running, do you notice one of the power tubes glowing brighter or with hot spots the other doesn’t have? Look at them as you flip on the standby, as it is sometimes more noticeable when you first put power to them. Get something non-conductive, like a wooden pencil or chopstick, and tap each tube. If something has come loose inside of a tube, this normally finds it.

There is an easy procedure for checking preamp tubes. The easiest way is to start at V1. There is a tube chart here to tell which one that is:

https://www.prsguitars.com/documents/mt15_tube_chart.jpg

Replace V1 with a tube you know is good. If there is no difference, put back the original tube and swap out V2, and so on down the line for the preamp. You can do this with one spare 12AX7 tube. While there is a chance more than one tube would be bad, it’s such a slim chance that this is a better first salvo.

Mesa Boogie has a good tech article that covers this and more.

https://mesaboogie.zendesk.com/hc/en-us/articles/216599018-How-can-I-troubleshoot-tube-issues-