clashcityrocker Posted August 16, 2012 Share Posted August 16, 2012 So 3 songs into our set tonight my amp (hartke lh1000) started smoking and cut out,this has never happened before and I'm shitting my pants as my ashdown died on me two months ago. I was on bridge mode,full 1000w,into a 2x15 laney cab (not mine),any ideas?I have a gig tomorrow night so bit pissed off and worried! Thanks a lot in advance,Simon Quote Link to comment Share on other sites More sharing options...
charic Posted August 16, 2012 Share Posted August 16, 2012 What's the ratings of each? Particularly the ohms rating? Doesn't sound like a quick fix unfortunately... Quote Link to comment Share on other sites More sharing options...
clashcityrocker Posted August 16, 2012 Author Share Posted August 16, 2012 4 ohms head asumed the cab was 4 being a 2x15?! Even though I have played thru a 8hm cab on this 4 ohms setting many a time with no problems. Anyone know a good amp fixer in the milton keynes area?!Si Quote Link to comment Share on other sites More sharing options...
stingrayPete1977 Posted August 17, 2012 Share Posted August 17, 2012 A 1000 watts into a single Laney 1x15 then? Quote Link to comment Share on other sites More sharing options...
stingrayPete1977 Posted August 17, 2012 Share Posted August 17, 2012 Ah read it again 2x15, it's early! Quote Link to comment Share on other sites More sharing options...
BigRedX Posted August 17, 2012 Share Posted August 17, 2012 Bridge mode on most amps is double the minimum load of each channel. To run a 4Ω load in bridge mode means that the amp must be capable of running down to 2Ω each side in dual channel mode. Can your Hartke amp do this? Quote Link to comment Share on other sites More sharing options...
clashcityrocker Posted August 17, 2012 Author Share Posted August 17, 2012 (edited) I presume so as its a feature on the amp as standard and was made to go with my harkte 810 which is 4 ohms. Would putting a 4ohms load into an 8 ohm cab damage the amp? On the back of the laney cab it had like 4 inputs (but no writing) so just plugged into one of the 2 jack inputs. The cab also had a XLR input,could it of been a PA cab?! Thanks Simon Edited August 17, 2012 by clashcityrocker Quote Link to comment Share on other sites More sharing options...
charic Posted August 17, 2012 Share Posted August 17, 2012 [quote name='clashcityrocker' timestamp='1345190714' post='1774675'] 4ohms load into an 8 ohm cab damage the amp? [/quote] I believe so unfortunately. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted August 17, 2012 Share Posted August 17, 2012 Bridging should almost never be employed into a low impedance load. There's nothing to be gained except damaging the head by driving too low an impedance load or blowing the drivers with too much voltage swing, or both. Bridging should only be used into a high impedance load, say 16 ohms, which the amp would otherwise not be capable of driving to full output. The mechanics of what bridging does isn't about watts, it's about voltage swing. An instructive paragraph in the owner's manual about when to bridge, and more important when not to, should be SOP, but IME it's a topic that's seldom, if ever, addressed. Quote Link to comment Share on other sites More sharing options...
neepheid Posted August 17, 2012 Share Posted August 17, 2012 According to the manual for the LH1000, the minimum impedance for bridge mode is 4 ohms. You say you were using a jack socket on the cab - how did you hook it up - a Speakon > Jack cable? The bridge output on an LH1000 is only supposed to come out of the Speakon, I think. You "assumed" the cab was 4 ohm? So you don't know what the impedance was for definite? Quote Link to comment Share on other sites More sharing options...
clashcityrocker Posted August 17, 2012 Author Share Posted August 17, 2012 Yeah speakon from head to jack at cab. And yeah I assumed,I have played in bridge mode thru a 8ohm 410 marshal loads of times with no,obvious,problems. Looks like more than an easy fix,gutted to say the least after my abm head mother board melted last year! Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted August 17, 2012 Share Posted August 17, 2012 theres a trend here then. these amps are getting enough air? Quote Link to comment Share on other sites More sharing options...
0175westwood29 Posted August 17, 2012 Share Posted August 17, 2012 I personally wouldnt use a cab if i didnt know its rating to much of a risk for me. Andy Quote Link to comment Share on other sites More sharing options...
clashcityrocker Posted August 18, 2012 Author Share Posted August 18, 2012 [quote name='LukeFRC' timestamp='1345226302' post='1775314'] theres a trend here then. these amps are getting enough air? [/quote] Yeah both have working fans,the ashdown was sat for 3 months untouched then died on first start up. The hartke has been fine for the 6 or so months I have owned it. I think it must be running it on bridge thru an 8 ohm cab that has done it,does anyone know the damage this may cause? Thanks a lot everyone for their advice and thoughts,Si Quote Link to comment Share on other sites More sharing options...
Graham Posted August 19, 2012 Share Posted August 19, 2012 If memory serves, if you run an amp into a cab at too low an impedance then the amp can overheat (which is what it sounds like has happened) as the cab is drawing more power than the amp is designed to handle - I'm sure someone with more knowledge than me can confirm / refute this and explain why. Quote Link to comment Share on other sites More sharing options...
dincz Posted August 19, 2012 Share Posted August 19, 2012 [quote name='Graham' timestamp='1345371609' post='1776669'] If memory serves, if you run an amp into a cab at too low an impedance then the amp can overheat (which is what it sounds like has happened) as the cab is drawing more power than the amp is designed to handle - I'm sure someone with more knowledge than me can confirm / refute this and explain why. [/quote] As far as solid state amps are concerned, yes. The key is in the word "impede". A high impedance cab impedes the flow of current from the amp. A low impedance cab impedes it less. A bit like pouring water down a thin pipe compared to a fat one. Quote Link to comment Share on other sites More sharing options...
clashcityrocker Posted August 19, 2012 Author Share Posted August 19, 2012 Cheers guys,opened the head up and from what I can see nothing has melted and was on for 2 hours with no problems,wasn't playing so could still over heat when played thru but touch wood it will be ok. Si Quote Link to comment Share on other sites More sharing options...
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