Crate gx-15r - A buzz together with clean sound

[Medeiros]

Hello everyone
Needing help with my Crate gx-15r. It is s making a small buzz together with the clean sound, like a small fuzz. I love the clean sound of this amp, but now it is making me crazy, I have clean all the pots and the circuit board with alcohol isopropyl and also with a cleaner spray for contacts. Could anyone help me with this. Thanks in advance, and there's maybe some mistakes on my english write, sorry about that
Luis Medeiros

[Enzo]

Is this a noise that ONLY occurs when you play notes? Or does it sit there making this hum all the time it is turned on?

If it only occurs while playing, then it suggests a speaker with a rubbing voice coil. Also possible are a cabinet buzz - something is loose and rattles.

If the buzz is more a hum - sounds like when you touch your guitar cord - then it is electrical. Could be as simple as a loose ground, or could be a problem with the power supply, like a failed filter cap.

[alexradium]

If the amp has also a distorted channel always running and just switched out,it can be radiated on top of the clean,in general it should be grounded at some point.

[Medeiros]

Is this a noise that ONLY occurs when you play notes? Or does it sit there making this hum all the time it is turned on?

If it only occurs while playing, then it suggests a speaker with a rubbing voice coil. Also possible are a cabinet buzz - something is loose and rattles.

If the buzz is more a hum - sounds like when you touch your guitar cord - then it is electrical. Could be as simple as a loose ground, or could be a problem with the power supply, like a failed filter cap.

Hi thanks for your interest and support, the buzz happens only when playing, I ve try allready connected to another speaker wlth the same bad result. The sound seems like I had together the distrocion sound connected in a very low volume. When I don't play even with the guitar connected it doesn't make any open audible noise. Guitar is an used cheap ibanez gio

[Medeiros]

Is this a noise that ONLY occurs when you play notes? Or does it sit there making this hum all the time it is turned on?

If it only occurs while playing, then it suggests a speaker with a rubbing voice coil. Also possible are a cabinet buzz - something is loose and rattles.

If the buzz is more a hum - sounds like when you touch your guitar cord - then it is electrical. Could be as simple as a loose ground, or could be a problem with the power supply, like a failed filter cap.

If the amp has also a distorted channel always running and just switched out,it can be radiated on top of the clean,in general it should be grounded at some point.

Hi thanks, it could be, do you know how I can found that source of distortion, that "shunt" and grounded properly or mute it, even I have to neutralize the distorced channel since I don't use it anyway. Hope you can help
Luis Medeiros

[J M Fahey]

If somebody posts the schematic I might find a way to add some extra muting to dirty channel when "Off".

[DrGonz78]

Courtesy of a post by nosaj.
https://music-electronics-forum.com/...7&d=1502246647

[Medeiros]

Sir I found the schematic going below thanks for your help

[Medeiros]

Schematic Crate GX-15R

Sir I found the schematic going below thanks for your help

http://music-electronics-forum.com/a...64-24701c4.pdf

posted by The Dude


http://music-electronics-forum.com/attachments/5546d1245133564-24701c4.pdf

[Medeiros]

Thanks Dr.Gonz78

[Medeiros]

Sir I found the schematic going below thanks for your help

Courtesy of a post by nosaj.
https://music-electronics-forum.com/...7&d=1502246647

[QUOTE=Medeiros;539758]http://music-electronics-forum.com/a...64-24701c4.pdf

posted by The Dude


http://music-electronics-forum.com/a...64-24701c4.pdf

[Medeiros]

Thank you sir

[J M Fahey]

Just checked the schematic.

Sadly,in this quite simplified amplifier, switching is not electronic (Fets or transistors) but the simplest mechanical, a plain push switch, thatīs why this amp does not have a footswitch.

I suggest you set P1: "Gain" to 0, do you still have the background buzz?
Because in that position IC1 pins 7 to 6 gets shorted and that Op Amp section gets fully muted.

Try it and post results.

If not enough, I can suggest a more drastic lobotomy which mutes it even more, requires desoldering a couple components and you should add a small switch at front or back panel to enable/disable it.

But letīs try the above suggestion first.

[Medeiros]

Just checked the schematic.

Sadly,in this quite simplified amplifier, switching is not electronic (Fets or transistors) but the simplest mechanical, a plain push switch, thatīs why this amp does not have a footswitch.

I suggest you set P1: "Gain" to 0, do you still have the background buzz?
Because in that position IC1 pins 7 to 6 gets shorted and that Op Amp section gets fully muted.

Try it and post results.

If not enough, I can suggest a more drastic lobotomy which mutes it even more, requires desoldering a couple components and you should add a small switch at front or back panel to enable/disable it.

But letīs try the above suggestion first.

Step one without mutilating
Results, I turn gain and level to zero.
No it sounds good, I thought I've try it before, but of course not,... So sir I really appreciate your help, and all the others advises and detailed lessons from you and the others in this forum thread . Late night I'll be practicing my very very hard Hey bi Jimi, clean loud with reverb. Wish you all the best