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Posted

Dear fellas, last night at rehearsal, playing with may little mark tube 800 and a MB new york 212 I noticed some weird noises coming of the speakers and the they kept moving even with no sound being fed. It sounded like wind or some fire burning.. Fortunately there wasn't any smoke involved. I disconnected the bass, changed speaker cable, power cable, restarted the amp.. Nothing worked. As I have another amp and set of speakers at the studio, I found out that the issue was the amp, as this issue was still happening with the other speakers. My description might be a little vague, but, does anyone have any idea what might be causing this. 

I forgot to mention that this noises still happen wen amp is muted. 

I'll try to post some video later. 

Thanks in advance. 

Posted

I’m not overly familiar with these amps but I believe they have a tube and a solid state side, have you tried cutting out the tube side and just running on solid state, then the other, is it just one side causing the problem? 
if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 
Does the sound have a hollow echo, if so the tube has gone microphonic. 

Posted
1 minute ago, Bunion said:

I’m not overly familiar with these amps but I believe they have a tube and a solid state side, have you tried cutting out the tube side and just running on solid state, then the other, is it just one side causing the problem? 
if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 
Does the sound have a hollow echo, if so the tube has gone microphonic. 

Yes, I tried that too. Both the solid state and the valve side sound the same. 

 

 

Posted

Bad luck. I'm afraid MarkBass amps aren't really repairable at component level and MB don't supply any technical data to repairers making things doubly difficult. Their service, such as it is, is done by Real Electronics https://www.realelectronics.co.uk/repairs.html who essentially just do full board replacements at upwards of £200. To be fair their fees are stated up-front and you will end up with everything inside replaced so effectively a new amp

  • Thanks 1
Posted
10 hours ago, Bunion said:

if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 

I believe the tube is permanently soldered to the pre-amp board so removing/replacement is not possible.

@Phil Starr is correct in his summary as we've both been through trying to get MarkBass kit repaired.

These are the costs from Real from a few years back. I suspect they will have increased now.

£35 to diagnose the problem, which you get back if you go ahead. £69 fixed labour to repair, £18 courier fee to send it back + parts.

The "parts" will be whatever boards need changing.

  • Thanks 1
Posted
2 minutes ago, BassBunny said:

I believe the tube is permanently soldered to the pre-amp board so removing/replacement is not possible.

That’s a bit naughty!! 

Posted (edited)

I can confirm the tube is soldered. I took a look to see if there was any identifiable problem. 

 Update: I dont think the issue is the tube. At least  it`s not going microphonic as i gave it some  light touches with no influence on the noise.

 

IMG_20220301_122752.jpg

IMG_20220301_122739.jpg

Edited by A.G.E.N.T.E.
Test update
  • 2 years later...
Posted (edited)

I have a similar problem with my Tube 500. I bought it second hand about 3 years ago and it did have an intermittent noise which didn't bother me too much until it started being more noticeable and frequent and eventually cutting out. I sent it to real electronics and they did a complete pot change as they bench tested it and couldn't find a valve fault. £200 odd spent. But it was still happening and every time I turned it on it'd go through a few minutes of being ok and then a few crackles and grumbles but usually settled down. But now it has no volume on the Tube side of the pot, still works ok on SS side. So to be honest I'm just using it as it is and it's ok, its been a great amp and was handy having 2 inputs. I've had my use out of it and will see how long it lasts. I've seen the newer LM IV for less than £500 so I might have a look at some point. 

 

That valve of yours look a bit worse for wear though? I've attached a pic from my 2016 model.

 

 

 IMG_0314.thumb.jpg.015b38ddd15d41f032e1487381c00bdf.jpg

Edited by paddybass

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