Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Greetings all. Hoping someone might be able to point me in the right direction. I own a Crate BX 160 amp, it is a beast. Recently, when it is powered on, regardless of a bass guitar being plugged in, there is a consistent for lack of a better term 'raspberry' sound coming through the speaker and a minimal / intermittent crackling effect think listening to a record / turntable. All the input and master volume could be turned all the way down and it is still present. When I plug my bass in, all noises remain. If I turn the main volume master and input up, the noise is there but it doesn't get louder. More often than not, the bass can drown it out. I thought I had confined the source to the cable that connects the speaker itself to the main input Jack on the electrical board. After getting a new cable, nothing changed. I've even tried the line out into my preamp interface for recording and luckily it is clean, no raspberry sound or crackling so it would seem that the issue is the connection on the circuit board from where the input Jack is to the main electrical component. Hoping someone might know of a fix for this. Thanks in advance.

sorry I cant help

but welcome to the site

hopefully someone will come along and know how to fix this

If the amp has an Effects Loop, try plugging a short patch cord between Send and Return.

All I have is the power amp schematic, I have never seen the pre-amp schematic.
It shows there is a send and return jack so that might be good news.

If the noise disappears when you plug a patch cable from the line out to the line in jacks as Loudthud suggested it means the line in jack is dirty.

The line in jack has a switch in it that disconnects it from the line out jack when a plug is inserted into it, no plug and it is connected to the line in jack.

A quick spray with Deoxit and then insert a plug several times might dislodge the dirt and restore the amp to normal.

crate - BX 160.pdf

If the volume doesn't change with position of the knobs or anything, I'd be questioning the power supply caps and maybe output transistors.

Quote from: Untilitkills83 on May 08, 2023, 12:58:21 PMGreetings all. Hoping someone might be able to point me in the right direction. I own a Crate BX 160 amp, it is a beast. Recently, when it is powered on, regardless of a bass guitar being plugged in, there is a consistent for lack of a better term 'raspberry' sound coming through the speaker and a minimal / intermittent crackling effect think listening to a record / turntable. All the input and master volume could be turned all the way down and it is still present. When I plug my bass in, all noises remain. If I turn the main volume master and input up, the noise is there but it doesn't get louder. More often than not, the bass can drown it out. I thought I had confined the source to the cable that connects the speaker itself to the main input Jack on the electrical board. After getting a new cable, nothing changed. I've even tried the line out into my preamp interface for recording and luckily it is clean, no raspberry sound or crackling so it would seem that the issue is the connection on the circuit board from where the input Jack is to the main electrical component. Hoping someone might know of a fix for this. Thanks in advance.

I'm re-reading this now and realize that you said the line out is clean.  If this is the case, then it couldn't be related to input whatsoever as this would be evident in lineout.  I'm thinking something is up with the output transistors.