Speaker issue with tube amp

[Erik Aa]

I have a Traynor yba-1a bass amp that I recently switched all large electrolytic caps in, except the small ones for bias, etc. i plan to switch those too but they are difficult to find in the right values.

Here is my question. When I play the bass loud on a 600w 410 cab, I get a slight scratching sound from the speakers in certain frequencies at high volume. It is not tube overdrive distortion.  Can this issue be a result of the remaining old electrolytic caps? Or is it perhaps a preamp tube issue? Or simply blown speaker?

Any and all suggestions/help is much appreciated.

Thanks!

[Platefire]

First thing I would do is try another known good speaker cab that you could crank up to the same level and see if it does the same thing. If it does it's probable in the amp. If it doesn't with the different speaker, it was the speaker cab. So if you find it's wasn't the speaker cab, then it's time to check the amp out

[Jennings]

Definitely check the cab furniture out…sometimes screws, handles, loose speaker fixings, hanging wires, or even washers that have ended up lodging in/around the speakers, all can give rise to odd noises which sound like they might be the amp or speaker.

[Erik Aa]

Thanks guys. I will perform some more tests.

[mresistor]

Also make sure the power tube sockets and preamp tube sockets pins are clean and tight. Sometimes the physical vibration of the bass signal at the cabinet can cause strange sounds from loose or dirty contacts.