Jeid Posted June 14, 2006 Report Share Posted June 14, 2006 I was at band practise last night and when I'd stopped playing, I noticed that some dude was faintly talking through my amp. So, time for new tubes.I have a Mesa Boogie .50 Caliber+ Head. Its a beast.It has Groove tubes in the power section just now, but it looks like the original stock pre amp tubes.Any recommendations for this beast? I've been looking at Svetlana's and JJ's.I need 2x 6L6's, 4x 12AX7's and 1x 12AT7. Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 15, 2006 Report Share Posted June 15, 2006 how does the amp sound when you play?You sure its not just signal interference?Picked up everything from taxis to police radio through various pieces of gear over the years but its never meant that my tubes on the amps were gone Quote Link to comment Share on other sites More sharing options...
Jeid Posted June 15, 2006 Author Report Share Posted June 15, 2006 I'm pretty sure its the tubes. Its starting to fizz on the overdrive channel, even at lower gain settings. And the clean channel just sounds a bit flabbier than it used to. Quote Link to comment Share on other sites More sharing options...
Frosty Jack Posted June 15, 2006 Report Share Posted June 15, 2006 Your tubes may be on the way out, but I don't think that has anything to do with picking up strange voices, does it?We once recorded a practice, and listening back discovered a note perfect trumpet solo from some European radio station. It fitted absolutely perfectly, so we kept it. Quote Link to comment Share on other sites More sharing options...
Guest Gasss Posted June 15, 2006 Report Share Posted June 15, 2006 I was at band practise last night and when I'd stopped playing' date=' I noticed that some dude was faintly talking through my amp. So, time for new tubes.I have a Mesa Boogie .50 Caliber+ Head. Its a beast.It has Groove tubes in the power section just now, but it looks like the original stock pre amp tubes.Any recommendations for this beast? I've been looking at Svetlana's and JJ's.I need 2x 6L6's, 4x 12AX7's and 1x 12AT7.[/quote']Preamp tubes don't tend to wear out. You'd only have to replace them if one or more have gone microphonic - a lot of vintage amps are still on the original preamp tubes. You can test microphony by tapping them VERY lightly using a chopstick with the amp on. As Frosty and Lame said, this wouldn't account for picking up radio interference. Ever seen Spinal Tap? If the amp is losing headroom and starting to crap out, the power valves may flagging. Replacing them wouldn't affect the interference though. Groove Tubes are pretty overpriced but the bonus is that once you have your amp biased for them, you can just plug in new ones of the same power rating (they have their own scale). Watford Valves' Harma line seem to be highly regarded and are used by Radiohead and some other folk. Derek Rocco selects the best of current production valves, tests them rigorously then rebrands them. Make sure you get your amp rebiased. Quote Link to comment Share on other sites More sharing options...
Guest lime ruined my life Posted June 15, 2006 Report Share Posted June 15, 2006 mine has no headroom, and craps out almost imediately. Do you think if i replaced my power valves with the same type i'd need to get it rebiased? Quote Link to comment Share on other sites More sharing options...
Bass Cadet Posted June 15, 2006 Report Share Posted June 15, 2006 Do you think if i replaced my power valves with the same type i'd need to get it rebiased?Yes you probably will - I've got a WEM in the same state. I got new valves but they just run a bit too hot. It's like playing plugged into a farrier's forge! Mmmmmm...... I must get round to sorting that out........ Quote Link to comment Share on other sites More sharing options...
Guest lime ruined my life Posted June 15, 2006 Report Share Posted June 15, 2006 bah! it's such a hassle! it doesnt even have a trim pot, i guess its proabbly the perfect excuse to stick one in. Quote Link to comment Share on other sites More sharing options...
Jeid Posted June 15, 2006 Author Report Share Posted June 15, 2006 Mesa's don't need re-biasing do they? Quote Link to comment Share on other sites More sharing options...
Guest lime ruined my life Posted June 15, 2006 Report Share Posted June 15, 2006 i know some brands have auto biasing technology, but i dont know if that includes mesas, you'd have to check the model hand book or website. Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 15, 2006 Report Share Posted June 15, 2006 Mesa's don't need re-biasing do they?Think your right there but dont quote me on that one!!i have a couple of boogie amps that dont need biased, but am unsure if all their models are like that.I have 2 marshall dsl 50's that were a bugger on power amp valves.Re-Biased them myself every change but the valves wouldnt really last more than 6 months and that wasnt with excessive playing!Maybe to do with temperature changes and the amp not able to cool down properly after use. Quote Link to comment Share on other sites More sharing options...
Jeid Posted June 15, 2006 Author Report Share Posted June 15, 2006 I'm pretty sure they don't. I did read it somewhere in a Boogie booklet. I'll need to do some investigation into that one!My amp is actually pretty close in design to a Mark I. I'll see what I can dig up though... Quote Link to comment Share on other sites More sharing options...
Jeid Posted June 15, 2006 Author Report Share Posted June 15, 2006 Question answeredMesa Boogie claim their amps don't need biasing.Only true if you use Mesa screened tubes or tubes that have been selected to match the Boogie biasing specification or if your tube supplier has tested and selected the tubes for you. The way Boogie get away with not fitting bias adjustments to their amps is they recommend you fit only Mesa tubes. These tubes are screened and tested to within a narrow specification so that the biasing adjustment is not necessary. Most good tube suppliers can offer you any tube screened to the Boogie spec if you mention you have a Boogie amp. The tubes used and badged by Mesa are manufactured from one of the 3 main plants remaining today. The only difference is that they are tested and screened to match their amplifiers and they also have a Boogie logo printed on them. Otherwise the tubes are the same as any other produced by Russia, Europe or China Quote Link to comment Share on other sites More sharing options...
Guest texjamm Posted June 15, 2006 Report Share Posted June 15, 2006 This might be slightly off topic but a couple of questions re-valves:Er...what is re-biasing and why?Does this only apply to power valves or pre-amp valves as well??( Quote Link to comment Share on other sites More sharing options...
Lame Guitarist Posted June 16, 2006 Report Share Posted June 16, 2006 This might be slightly off topic but a couple of questions re-valves:Er...what is re-biasing and why?Does this only apply to power valves or pre-amp valves as well??(Bias is the negative voltage applied to the grid of a tube (valve) in order to control electron flow.Just Power amp valves Tex, They have to be set to have the correct current through them cos if not the amp will either run too hot or too cold.Results in usually burning out the tubes too quick or giving a crap sound and can damage the components of the amp as well. Quote Link to comment Share on other sites More sharing options...
Guest texjamm Posted June 16, 2006 Report Share Posted June 16, 2006 Bias is the negative voltage applied to the grid of a tube (valve) in order to control electron flow.Just Power amp valves Tex' date=' They have to be set to have the correct current through them cos if not the amp will either run too hot or too cold.Results in usually burning out the tubes too quick or giving a crap sound and can damage the components of the amp as well.[/quote']Aaaah......the fog clears........cheers for explaining Quote Link to comment Share on other sites More sharing options...
Rob Karloff Posted July 2, 2006 Report Share Posted July 2, 2006 Valves are never my problem, it's the cheap shit quality transformers they seem to be using in Marshalls these days. My EL34 50/50 has one Drake OPT and one Dagnall OPT, and the Dagnall is now toast (It crapped on me playing through one of the Laney 4x10 cabs at Toms last practise). The OPT in my JCM2000 head is also crispy fried, I haven't looked to see what brand OPT it has as I'm still pissed off that it's eaten OPT number 3. My action plan is to fit Drake units to all my amps, either the same unit as in the B channel of my 50/50 or the spec of OPT used in the 100/100 so that all my amps run over-sized OPTs.In terms of valves, unless you're spending money on old valve stock units such as the Siemens in my JCM800, one brand is as good as another. As someone pointed out, only 3 or so valve plants exist in the world now, and I'm pretty sure at least 2 are in Russia. Groove Tubes and many other "brands" are the same damn valve with a different logo on them, despite what the marketing garb tells you. The only thing you need worry about is installing 2 or 4 power valves with as close a match to each other as you can get. Even most matched sets from Marshall or whoever still have a significant variation from one valve to the next, so the only way to really do this is to have a good stock yourself, or trust that a supplier such as Watford Valves will send you a pair or quad as close as they can get! The closer (and therefore better) the valves are matched, the more you pay. But the service life will be MUCH better, and general sound quality should be more even. In a Marshall, one half is a push, one half a pull (so 1 push 1 pull in a 50W, 2 push 2 pull in a 100W). Ideally you want the combined values for the push to be as close to the combined values for the pull as you can get. If you shell out for pricey matched sets, then make sure you get the spec sheets for those sets, partly for this purpose and partly so you know your valve supplier has actually spec'd them!To be honest, as long as you're putting the same type of valve in as you're taking out, you do not run a huge risk of causing damage to the amp. You'd be VERY unlucky to have a valve of the same type be far enough away in performance compared to the old one to cause damage. So, if you're in a bind and have the valves to do it, whack them in and play. Swap the entire set if possible to further minimise. If it's from a push-pull design amp, swap them over and keep them in the same grouping as they were in the amp you swipe them from. Mis-matched speaker cab and head impedance settings are the real amp killers, not some un-biased valves. Modern amps like the JCM2000 series are simple to bias if you have a good quality multimeter. Don't bother if your meter cost less than 100 or hasn't been calibrated in donkeys, any measurements you might take would not be accurate. You can't even cheat by taking the existing bias measurements and setting the new valves to the same, as the valves wear the bias reading will change.Marshall have a service department down at the factory. Phone the main number and ask for it, they will organise the pickup of your amp from a business address by courier, and an engineer will call to advise what work is needed and the cost. We recently had Sid Karloff's early Mk II JCM800 2204 serviced by them as well as the Mant's very old/worn and abused JMP bass series head (which sounded like death when they got it). The cost was reasonable, and both sound very crisp and punchy now. Quote Link to comment Share on other sites More sharing options...
Jeid Posted July 2, 2006 Author Report Share Posted July 2, 2006 I use a Boogie, but great advice for any Marshall amp owner(the tech bit at the end)I think to save myself hassle, I'm gonna put Groove Tubes in again. Quote Link to comment Share on other sites More sharing options...
stuartmaxwell Posted October 15, 2006 Report Share Posted October 15, 2006 speak to dennis marshall from this company about how to make your mesa sound even better.http://www.emersonwilliams.com/html/home.htmive got my 400+ in with him just now and cant wait to hear how it sounds on return. boom! Quote Link to comment Share on other sites More sharing options...
threeornothing Posted October 15, 2006 Report Share Posted October 15, 2006 I had a valve actually melt in my amp the other day, playing at fucking bedroom levels.DON'T BUY VALVES FROM R&B! Quote Link to comment Share on other sites More sharing options...
Jeid Posted October 16, 2006 Author Report Share Posted October 16, 2006 I bought mine from Hotrox. fantastic service. Got me some JJ tubes. all sorted now Quote Link to comment Share on other sites More sharing options...
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