Moved to Instruments & Amps per forum policy.
Be more specific. Squeals at high volumes. Does that mean when you PLAY loud it adds this sound? or does it mean that turning the volume controls up makes it squeal? For example, will it squeal with the volumes maxed and no guitar connected? Once it starts is it a continuous sound? Or is it parasitic, occurring only on peaks.
Do ANY of the controls affect the sound of the squeal in ANY way? (Loudness, frequency, tone of it) WHich ones if any?
I don;t know how you determined it was not feedback. Ball up your fist and whack the top of the amp while it runs. That will usually reveal loose connections that may be exacerbated by the speaker vibrations. Tube squeal can often be stopped by grasping a tube firmly. Use a rag if it is too hot. Has that been done, grasp each tube? Certainly other parts than tubes can be microphonic. And newness of a tube or part is no guarantee that it is 100%.
Do ANY of the controls affect the sound of the squeal in ANY way? (Loudness, frequency, tone of it) WHich ones if any?
I don;t know how you determined it was not feedback. Ball up your fist and whack the top of the amp while it runs. That will usually reveal loose connections that may be exacerbated by the speaker vibrations. Tube squeal can often be stopped by grasping a tube firmly. Use a rag if it is too hot. Has that been done, grasp each tube? Certainly other parts than tubes can be microphonic. And newness of a tube or part is no guarantee that it is 100%.
any effects patched in inline or on the loop or is this just the amp with your guitar(which is what a Strat or...) and have you tried another signal source as in low level audio?
you should try Enzo's suggestion about the tubes.
also is this happening on both the clean and dirty channels?
you should try Enzo's suggestion about the tubes.
also is this happening on both the clean and dirty channels?
Last edited:
Did you open it up already? (mains lead unplugged, and left for a while to make sure capacitors are drained)
If so, could you post some pictures of the insides and particularly the main PCB?
Some of the newer guitar/ bass amplifiers have SMPS PSU's for the B+ voltage as these are more compact (lighter!) than conventional PSU's. There's a big Fender bass amp which has this, and probably a few others. And I believe some/ all of the blackstar amps have SMPS PSU's.
These work by (attention: extremely non-engineeringlike description) creating a alternating current, with a much higher frequency than regular mains voltage (50Hz, 60Hz). The reason for this is that transformers can be made a lot more compact and work better for these higher frequencies. The drawback is that these high frequencies can find their way to the audio path, which leads to a whining noise. Careful layout, grounds in particular, and proper filtering can keep this from happening. But if there's a not so nice ground somewhere, or caps going bad, this can cause trouble.
If so, could you post some pictures of the insides and particularly the main PCB?
Some of the newer guitar/ bass amplifiers have SMPS PSU's for the B+ voltage as these are more compact (lighter!) than conventional PSU's. There's a big Fender bass amp which has this, and probably a few others. And I believe some/ all of the blackstar amps have SMPS PSU's.
These work by (attention: extremely non-engineeringlike description) creating a alternating current, with a much higher frequency than regular mains voltage (50Hz, 60Hz). The reason for this is that transformers can be made a lot more compact and work better for these higher frequencies. The drawback is that these high frequencies can find their way to the audio path, which leads to a whining noise. Careful layout, grounds in particular, and proper filtering can keep this from happening. But if there's a not so nice ground somewhere, or caps going bad, this can cause trouble.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.