markstuk Posted November 28, 2011 Share Posted November 28, 2011 (edited) Hi, Just picked up a lovely F500 but am having some interesting issues with regard to my BareFaced S12T... I suspect it's unstable into the load the S12 (nominally 4 ohms) offers, the initial master gain structure is much steeper compared to my RH450 (athough absolutely they're both about the same volume as I would expect), and if I turn the master up quickly (or induce feedback) the F500 cuts out.... When I plug the F500 into my 4 Ohm EBS 410 the self switching off stops although the gain structure is also pretty aggressive (ie it's really loud at 3, ear bashingly loud at 5, and into output stage distortion at 6..) My suspicion is that the F500 is on the knife edge of stability at around 4 ohms... Any thoughts folks? Edited November 28, 2011 by markstuk Quote Link to comment Share on other sites More sharing options...
dave_bass5 Posted November 28, 2011 Share Posted November 28, 2011 I dont know much about these things but i dont think something is working right. Ive been using MB heads (currently a F1) for about 6 years, always in to a 4 ohm cab (Schroeders) and never had any issue, done well over 500 gigs with this set up. I have had my SA450 cut out on me a few times in one evening when i was using a rehearsal studios cab. Every time i hit a loud note or slapped (i know, i really shouldn't) the head would shut down. It turns out the cab was faulty and the head was just protecting itself. Ive never had any other issues with my heads in to 4ohms cabs. I know this doesn't help much, Ijust thought I would share my MB experiences with 4 ohms cabs. Quote Link to comment Share on other sites More sharing options...
markstuk Posted November 28, 2011 Author Share Posted November 28, 2011 Thanks for posting.. I'm reasonably confident that the S12T is ok, simply because I use it all the time with my RH450. although I will get my meter out later and check that the impedence is not drifting somehow downwards.... [quote name='dave_bass5' timestamp='1322497265' post='1451564'] I dont know much about these things but i dont think something is working right. Ive been using MB heads (currently a F1) for about 6 years, always in to a 4 ohm cab (Schroeders) and never had any issue, done well over 500 gigs with this set up. I have had my SA450 cut out on me a few times in one evening when i was using a rehearsal studios cab. Every time i hit a loud note or slapped (i know, i really shouldn't) the head would shut down. It turns out the cab was faulty and the head was just protecting itself. Ive never had any other issues with my heads in to 4ohms cabs. I know this doesn't help much, Ijust thought I would share my MB experiences with 4 ohms cabs. [/quote] Quote Link to comment Share on other sites More sharing options...
Musicman20 Posted November 28, 2011 Share Posted November 28, 2011 The RH450 is safe lower than 4 ohms, (2.66) so it MIGHT be something to do with the cab, although I would think Alex would be able to sort it or diagnose this very quickly. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted November 28, 2011 Share Posted November 28, 2011 Does it work ok at lower volumes? Have you had problems with any other heads into the S12T? Is the F500 brand new? Quote Link to comment Share on other sites More sharing options...
markstuk Posted November 28, 2011 Author Share Posted November 28, 2011 Basically the S12T is fine with every other head I have/have had (RH450, Bassbase 600, QSC PLX) and the F500 is fine with other 4 Ohm nominal cabs.. The F500 is a few months old, but new to me, but has been playing happily with an AE212 with it's previous owner. Of course the three amps I've tried with the S12T are happy down to near 2 Ohms anyway.. Quote Link to comment Share on other sites More sharing options...
alexclaber Posted November 28, 2011 Share Posted November 28, 2011 Hard to say what's wrong then without doing an impedance sweep and/or opening the cab up! Not heard of any problems with a Markbass head and Barefaced cab before, though most are using the 500W Class AB or the 800W & 1200W Class D heads. Quote Link to comment Share on other sites More sharing options...
markstuk Posted November 29, 2011 Author Share Posted November 29, 2011 Run a meter over the cabs last night... I know this is only a nominal number but the S12T was showing about 3.6 ohms and the EBS 4.1 ... Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted December 3, 2011 Share Posted December 3, 2011 I remember that when I switched the jumpers in an F1 from US version to UK, there was some discussion about whether I should go for 240 or 230 V settings, and this led on to how variable the mains supply voltage can be. Is it possible that this problem could relate to, or be exacerbated by, mains supply issues? Quote Link to comment Share on other sites More sharing options...
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