Pete Academy Posted February 23, 2010 Share Posted February 23, 2010 (edited) A couple of weeks ago my LMK head stopped working during a gig. I faffed about and eventually plugged straight into the head, bypassing my Boss TU-2. I switched the amp off, then back on, and it worked perfectly for the rest of the second set. I used it at the last gig without the tuner and it worked perfectly. I think there may be a fault with the tuner or mains supply to it, causing some kind of spike. The operating manual doesn't mention anything about the amp's protection system, nor does it have a troubleshooting guide. I contacted Peter Murray from Markbass, who sent this reply: "Our amps have shutdown circuits that shut down the amp in cases of incorrect impedance (below 4 ohms), overheating, excessive input or short circuit (for example, bad wiring in a speaker cable). The amp shuts itself down to protect it from damage. That's why you're able to turn it back on. So it's possible that one of these things are issues... is the impedance of your cabinet/s below 4 ohms? Is your amp properly ventilated and is the fan working? Are you putting unreasonable input into the amp? Is your speaker cable good?" Just thought I'd mention this in case anyone else has a problem. Edited February 23, 2010 by Pete Academy Quote Link to comment Share on other sites More sharing options...
lemmywinks Posted February 23, 2010 Share Posted February 23, 2010 Happened to me a while ago, think it was a dodgy lead as one of my Planet Waves failed a couple of gigs later. Only happened the once in over a year of solid gigging, i always DI from m MXR M80 anyway so even if something did fail i'd still have bass through the PA Quote Link to comment Share on other sites More sharing options...
JTUK Posted February 23, 2010 Share Posted February 23, 2010 Sounds like a good system to me, if it saves the amp from any damage. Quote Link to comment Share on other sites More sharing options...
The Funk Posted February 23, 2010 Share Posted February 23, 2010 (edited) You could always stick your tuner elsewhere in the signal chain. Does the LMK have a tuner out / line out somewhere? That way you'd avoid excessive input if that's the problem and if it's the tuner causing it. EDIT: Just looked it up - it has a tuner out. Edited February 23, 2010 by The Funk Quote Link to comment Share on other sites More sharing options...
Musicman20 Posted February 23, 2010 Share Posted February 23, 2010 Glad they sorted it for you. Seem MB make pretty damn robust amps I like the fact it senses a problem and shuts down. Quote Link to comment Share on other sites More sharing options...
guybrush threepwood Posted February 23, 2010 Share Posted February 23, 2010 Cheers for posting this, it's really good to know. It's strange that it's not mentioned in the manual though... Quote Link to comment Share on other sites More sharing options...
dave_bass5 Posted February 26, 2010 Share Posted February 26, 2010 (edited) Could be just a coincidence about the tuner IMHO. Could have been the amp needed a certain time to re set itself and this coincided with the tuner being taken out of the equation. This happened to me a couple of years ago. I took my SA450 to a rehearsal room to use with their cab. After about 30 mins my amp died. After some messing about, changing kettle leads etc it all worked again, for another 10mins or so. It always seemed to cut out when i popped (yeah, there's an omen if i ever saw one). After the third time this happened i switched cabs and all was fine for the rest of the night. It turns out the Ampeg cab was known to be faulty and this must have been causing the head to turn off. Its never happened since. My SA450 also gets hot at some gigs and did shut down once. Its good to know it can look after itself. Edited February 26, 2010 by dave_bass5 Quote Link to comment Share on other sites More sharing options...
Pete Academy Posted February 26, 2010 Author Share Posted February 26, 2010 [quote name='The Funk' post='754958' date='Feb 23 2010, 01:15 PM']You could always stick your tuner elsewhere in the signal chain. Does the LMK have a tuner out / line out somewhere? That way you'd avoid excessive input if that's the problem and if it's the tuner causing it. EDIT: Just looked it up - it has a tuner out.[/quote] I tried the 'tuner out' socket. It doesn't respond very well, plus you can't mute the signal. Quote Link to comment Share on other sites More sharing options...
greggi g Posted July 12, 2021 Share Posted July 12, 2021 turn my Markbass on and it turns itself of after 30 seconds or so wait a while turn it on and same again, have bought another head (from a member of this site) but would be nice to see if other one could be fixed? ps fans works speakers fine all cables fine Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 13, 2021 Share Posted July 13, 2021 On 23/02/2010 at 08:47, Pete Academy said: A couple of weeks ago my LMK head stopped working during a gig. I faffed about and eventually plugged straight into the head, bypassing my Boss TU-2. I switched the amp off, then back on, and it worked perfectly for the rest of the second set. I used it at the last gig without the tuner and it worked perfectly. I think there may be a fault with the tuner or mains supply to it, causing some kind of spike. The operating manual doesn't mention anything about the amp's protection system, nor does it have a troubleshooting guide. I contacted Peter Murray from Markbass, who sent this reply: "Our amps have shutdown circuits that shut down the amp in cases of incorrect impedance (below 4 ohms), overheating, excessive input or short circuit (for example, bad wiring in a speaker cable). The amp shuts itself down to protect it from damage. That's why you're able to turn it back on. So it's possible that one of these things are issues... is the impedance of your cabinet/s below 4 ohms? Is your amp properly ventilated and is the fan working? Are you putting unreasonable input into the amp? Is your speaker cable good?" Just thought I'd mention this in case anyone else has a problem. Most modern amps have some kind of protection circuit and will cutout if over temperature or an over current is detected. It is perhaps a sign that the amp or cab has a problem. The other option is that you need a higher output amplifier. Quote Link to comment Share on other sites More sharing options...
Jus Lukin Posted July 13, 2021 Share Posted July 13, 2021 (edited) - Edited March 15, 2022 by Jus Lukin Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 13, 2021 Share Posted July 13, 2021 you mean 32 minutes ago, Jus Lukin said: Chaps, I think Pete Academy passed away some time ago. Given the context of the OP, I'm sure he'd be happy for us to continue discussing Markbass amp issues in this thread- but he is very unlikely to be responding himself. You mean you are still living? You have no right here, this is a zombie thread. 1 Quote Link to comment Share on other sites More sharing options...
Jus Lukin Posted July 13, 2021 Share Posted July 13, 2021 (edited) - Edited March 15, 2022 by Jus Lukin Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted July 13, 2021 Share Posted July 13, 2021 23 minutes ago, Jus Lukin said: Technically speaking, yes, but practically... meh, depends where you draw the line. Zemantics, they always go there when they have lost. Quote Link to comment Share on other sites More sharing options...
greggi g Posted July 13, 2021 Share Posted July 13, 2021 1 hour ago, Chienmortbb said: Most modern amps have some kind of protection circuit and will cutout if over temperature or an over current is detected. It is perhaps a sign that the amp or cab has a problem. The other option is that you need a higher output amplifier. Mine just stays on for 30 seconds then shuts down again. and continues to do that its fine if you wanna sound like less dawson on a double bass!!! Quote Link to comment Share on other sites More sharing options...
Jus Lukin Posted July 13, 2021 Share Posted July 13, 2021 (edited) - Edited March 15, 2022 by Jus Lukin Quote Link to comment Share on other sites More sharing options...
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