Issue with Ashdown ABM500

[Heatmonger]

My ABM500 just recently started making a pretty audible buzzing sound when powered on, and square wave, ****** sounding distortion when the pre is pushed.

I changed the tube out, so it doesn't seem to be a tube issue.

The DI does not exhibit these symptoms. Maybe a little more noise, but no square wave nasty sounding distortion.

It's not the speakers, I tried another head and it sounds fine.

Any ideas?

 

[B-string]

Take it to a tech, sounds like you have an issue only a tech can help with. Buzzing is either a ground problem or power supply, either one could cause the unpleasant distortion.

 

[Heatmonger]

It's not a very loud buzz. Kind of like the buzz you hear when you have high gain or fuzz kicked in. The bass signal is much more audible than the buzz, but distorted.

 

[floydman]

Does it happen if you are fully in solid state pre-mode ("clean") and fully in tube pre-mode ("grind")?

 

[Heatmonger]

Yes, it seems to happen regardless of which way the clean/grind knob is turned.

 

[BassmanPaul]

Sorry Bro but it's Tech Time. I'd get it in ASAP before anything else develops from this problem.

 

[RickenBoogie]

+1 take it in now, before it gets worse.

 

[Heatmonger]

Thanks for the input guys. I guess am going to have to take it into a tech when I have the moo-la.

 

[floydman]

cheap potential fix and general good practice- buy a can of tuner cleaner/lubricant from radioshack (my tech uses DeOxit) and hit all of the pots and sliders. I had a noise happening that was cleared up by this simple cheap fix.

 

[mroekalea]

Didn't you accidentally pushed the sub harmonics button, as you desribe it it looks to my the issue!

 

[Heatmonger]

Didn't you accidentally pushed the sub harmonics button, as you desribe it it looks to my the issue!

Why would hitting the subharmonics button cause the issue I have? Shouldn't it just cause an audible sub-octave? I've used the subharmonic before and I really doubt it is causing the issue.

Ashdown tech is suspecting the large capacitors on the power amp PCB have a cracked solder joint, or a lost earth track on the Preamp PCB.

 

[mroekalea]

When the sub harmonics level is to much it doesn't sound like a octaver anymore. Just a possibility which could be easily overlooked, but your sharp so not the issue. Just trying to help

 

[Heatmonger]

thanks for your help

 

[boristhespider7]

Wouldn't hurt to ask the Ashdown Tech support (via their website) whether there's any easy fix you can do yourself. I've always found them really really helpful (best customer service i've found so far). Usually get back to you within day or 2.

Once described a problem via email to them and they diagnosed a failed transformer. Without asking they popped one in the post the same day (for free!). Switched it out..problem sorted! I do live in the UK though so not sure if service will be the same in the US, but def worth contacting them

 

[BruceBass3901]

Just backing up what boristhespider7 said about the customer service from Ashdown... It is truly brilliant. Every time I have contacted them, I have recieved a reply within 2 days. Whether it be asking about how to fix something, order replacement parts or just to ask about different gear, they have always been helpful.

Between the amazing sound and amazing service, I can safely say that Ashdown are my favourite amp manufacturers

If only I could afford the stuff I really wanted from them

 

[Heatmonger]

Ashdown was actually quite helpful. They narrowed it down to the large capacitors on the power amp PCB having a cracked solder joint, or a lost earth track on the Preamp PCB. I am going to say it is a lost earth track, since the excess noise still occurs when i turn master volume down to zero. Unfortunately I am not an amp tech and I am not sure there is an easy fix.

Thanks for everyone's input!