Mark_Bass Posted March 21, 2013 Share Posted March 21, 2013 Hiya, Forgive me if this question has been asked before. I own a Mesa Boogie Big Block 750, and i really like the amp but the one thing that I'm not too keen on is the gain section. I play active basses and i only need to set the gain at 9 o'clock before the valves start to get driven. Id prefer more control from my gain control so when i dig in the valves don't get driven so much. The Mesa OD form the valves is great sometimes gets a little to compressed that end up getting lost in the mix form time to time. So the question is would you recommend maybe attenuating the input? My older mesa had an active\passive inputs and i assume thats for this very reason. Or could this be the case of exploring different makes of pre-amp valves? How much does the pre-amp valve affect the tone of signal? Is there brand of valves that offer a brighter tone? The thought im having is that maybe i should return to playing M-pulse head which enabled me to have a slightly more modern sound cleaner sound whilst still being able to cool up a more valve tone when needed. I only changed the amp becuase i found this forum and wanted to try new amps and explore the option of having a simpler set-up. Or do i stick with the amp and explore a new choice of cab - i've changed my head several times last year but my cab has remained the same. Its an ampeg SVT 410hlf - and whilst this wont help my gain problem might help me with the Eq unhappiness. Thoughts? advise? Quote Link to comment Share on other sites More sharing options...
franzbassist Posted March 21, 2013 Share Posted March 21, 2013 (edited) Well the manual says: [font=sans-serif][size=4]INPUT: This jack feeds the first tube in the all-tube preamp of the BIG BLOCK. It is set up with enough headroom to handle both passive and active style instruments. For active instruments you may find yourself running the GAIN control somewhere between 10:00 and 2:00 for optimum headroom. If you do hear a softclip creeping in at higher settings, don’t worry, this is the beauty of a tube front end.[/size][/font] [font=sans-serif][size=4]So it sounds like your amp is doing what it's meant to.[/size][/font] [font=sans-serif][size=4]If you don't like it then try a lower gain valve in V1. If you look at the page [url="http://www.thetubestore.com/Gain-Factor"]here[/url] it will give you an idea of the other valves out there.[/size][/font] [font=sans-serif][size=4]Enjoy![/size][/font] [font=sans-serif][size=4]Gareth[/size][/font] Edited March 21, 2013 by walbassist Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted March 21, 2013 Share Posted March 21, 2013 That page seems to miss an important bit about the different impedance of the different valves having an effect on the circuit, which shifts tone around in various possible watys depending on what the valve does, the two halves might do different things. Quote Link to comment Share on other sites More sharing options...
franzbassist Posted March 21, 2013 Share Posted March 21, 2013 [quote name='Mr. Foxen' timestamp='1363872237' post='2018680'] That page seems to miss an important bit about the different impedance of the different valves having an effect on the circuit, which shifts tone around in various possible watys depending on what the valve does, the two halves might do different things. [/quote] That's true Oli, but they do say this: Before you discover the new possibilities in your amp, let us give a [b]disclaimer[/b]. Your amp was originally designed for a certain type, and although tube amps are often forgiving, it may not have a tone that you like with a different tube type. For instance, changing the tube type doesn't only change the gain factor; there are other variables as well and your amp may have a circuit that is more particular than others. As a general rule, the substitutions we describe here should work well but there are exceptions and [b]we don't warranty[/b] any problems that result from trying mismatched tube types. Quote Link to comment Share on other sites More sharing options...
Mark_Bass Posted March 21, 2013 Author Share Posted March 21, 2013 (edited) [quote name='walbassist' timestamp='1363872374' post='2018685'] That's true Oli, but they do say this: As a general rule, the substitutions we describe here should work well but there are exceptions and [b]we don't warranty[/b] any problems that result from trying mismatched tube types. [/quote] So in otherwords it "should" be ok to try different valves just don't coming crying to us if your amp goes bang IS this something that you guys would recommend doing? Not that im going to blindly follow your every words but id be interested to hear of any experiences users have had when trying this out. Edited March 21, 2013 by Mark_Bass Quote Link to comment Share on other sites More sharing options...
franzbassist Posted March 21, 2013 Share Posted March 21, 2013 [quote name='Mark_Bass' timestamp='1363874839' post='2018734'] So in otherwords it "should" be ok to try different valves just don't coming crying to us if your amp goes bang IS this something that you guys would recommend doing? Not that im going to blindly follow your every words but id be interested to hear of any experiences users have had when trying this out. [/quote] Why not drop Mesa an email and ask them whether there are any issues trying different valves? Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted March 21, 2013 Share Posted March 21, 2013 It will probably cause no harm, but it will be a tone change as well as a gain drop. But if there is anyone I'd expect to do something in an amp that will make it blow up unexpectedly for a really minor thing, it is Mesa. Awesome 'design features' like going into oscillation if the output is unloaded, rather than most amps that only eat themselves if you try playing through them unloaded. Also live shielding, as in the shielding you will generally assume is grounded is carrying voltage. Quote Link to comment Share on other sites More sharing options...
victor5string Posted March 21, 2013 Share Posted March 21, 2013 Does your bass have a gain trim pot in the electronics? Dropping this right down could help a lot. Quote Link to comment Share on other sites More sharing options...
Mark_Bass Posted March 21, 2013 Author Share Posted March 21, 2013 [quote name='victor5string' timestamp='1363877977' post='2018795'] Does your bass have a gain trim pot in the electronics? Dropping this right down could help a lot. [/quote] Theres no gain pots just the eq, which i generally run flat or pretty much flat -just just a bit of extra treble boost more than anything else. I've emailed Mesa, i brought the amp used so theres probably no reason for them to worry about voiding any warranty. Quote Link to comment Share on other sites More sharing options...
franzbassist Posted March 21, 2013 Share Posted March 21, 2013 [quote name='Mark_Bass' timestamp='1363882147' post='2018884'] Theres no gain pots just the eq, which i generally run flat or pretty much flat -just just a bit of extra treble boost more than anything else. I've emailed Mesa, i brought the amp used so theres probably no reason for them to worry about voiding any warranty. [/quote] I think Vic means pop the lid off and see if there's a trim pot inside which can be adjusted, rather than what's on the front panel. Quote Link to comment Share on other sites More sharing options...
Mark_Bass Posted March 21, 2013 Author Share Posted March 21, 2013 [quote name='walbassist' timestamp='1363882245' post='2018887'] I think Vic means pop the lid off and see if there's a trim pot inside which can be adjusted, rather than what's on the front panel. [/quote] Ohhhhh i get ya! Great idea....thanks! :-0) Quote Link to comment Share on other sites More sharing options...
krispn Posted March 21, 2013 Share Posted March 21, 2013 I recently tried some new valves in my valve pre amp. The 12AX7's were just too hot and didn't give a pleasing tone but the 12AU7 was rhe perfect fit. I run my 'gain' at 3 o'clock and its just the right amount of 'fullness' to the signal without clipping. I'm not playing a Mesa head but you will get a difference if you try a less hot tube....just keep a fire extinguisher handy Quote Link to comment Share on other sites More sharing options...
franzbassist Posted March 21, 2013 Share Posted March 21, 2013 When I had an Ashdown LB30 I checked with them that it was okay to try lower gain valves in the preamp. They said it was, but it would change the character of the amp. My current amp, a Markbass TTE500, has four valves in it (one each for gain, compressor, eq and colour) and when I asked them they said that I should only use the valves the amp was designed around. So, check with the maker, as they should know best! Quote Link to comment Share on other sites More sharing options...
Mark_Bass Posted March 22, 2013 Author Share Posted March 22, 2013 Mesa got back to me saying they wouldn't recommend using different valves, partly for the change in possible change in tone. Now the newer version of the Big Block as a Passive\Active input switch on the front and i've spoken to Greg at Guitar Aid who said that he should be able to do something similar. Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted March 22, 2013 Share Posted March 22, 2013 Just occurred that MEsa also reccomend only using their own brand of valves, kind of tells you how useful their advice may be. Quote Link to comment Share on other sites More sharing options...
Mark_Bass Posted March 22, 2013 Author Share Posted March 22, 2013 [quote name='Mr. Foxen' timestamp='1363973886' post='2020433'] Just occurred that MEsa also reccomend only using their own brand of valves, kind of tells you how useful their advice may be. [/quote] Lol yeah thats pretty much what they said Quote Link to comment Share on other sites More sharing options...
xgsjx Posted March 23, 2013 Share Posted March 23, 2013 What about putting an EQ or Boost pedal between your bass & amp & turning it down so the output from it isn't so hot? That would mean you have more control over the input gain (obviously you need to increase the output gain accordingly). Would this not have the desired effect? There is a cheaper but harder option. Try backing off some of the bass's volume. I know its hard not to have it as far as it goes. Quote Link to comment Share on other sites More sharing options...
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