BluefoxIcy Posted March 12, 2008 Share Posted March 12, 2008 I'm glancing through microphone and instrument preamps and a few are coming to my attention, particularly... http://www.musiciansfriend.com/product/ART-Tube-MP-Project-Series-Tube-MicrophoneInstrument-Preamp?sku=180643 And http://www.musiciansfriend.com/product/ART-Tube-MP-Studio-Mic-Preamp?sku=180581 Anyone use either of these? Right now I don't need one but I'm curious; really I'm going for a fresh Epiphone Valve Junior half-stack and the BitMo Trio mod (has a sweet blues setting I really like), no pedals needed. The only thing that'd draw me to a tube preamp might be the potential to push my attack a little. Play light and you get clean, play harder and you get dirty, play really hard and you get real overdrive. I'd love to make light playing clean but make it really overdrive just a little faster, or maybe start screaming about halfway where it is now. Of course I'm talking about guitar. I'm so tempted to jack a mic into the fucker and overdrive the tube to see what I get; but I'm going to put in some serious voice training before I subject my empty room to my singing. Quote Link to comment Share on other sites More sharing options...
BluefoxIcy Posted March 13, 2008 Author Share Posted March 13, 2008 Did some digging. 12AX7 tubes run with 300V plate voltage; these things use 50V plate voltage (i.e. the tube doesn't work, but it glows a bit) and have a parallel circuit where the signal goes, using a silicon op-amp (blah!). http://www.cockos.com/forum/showthread.php?t=17220 http://www.gearslutz.com/board/geekslutz-forum/116542-tube-art-tube-mp-upgrade.html Another company was using a dirty trick, lighting the tube up with LEDs but the tube was completely non-functional (designed out). ~_~ You know what? A 12AX7 preamp circuit is a 115V in, 300V/6.3V out main transformer with 300V powering the plate and 6.3V powering the 12AX7 filament, 5 simple ground points, 6 resistors, 1 cap, and 1 volume pot (logarithmic trapezoidal). It doesn't even need an OT. Why is this a multi hundred dollar endeavor when using a $3 op-amp is a $70 endeavor? $10 tube, like $6 of parts versus a $3 4558.... Blahe. Music gear is such a shit market. Quote Link to comment Share on other sites More sharing options...
Dyne Posted March 13, 2008 Share Posted March 13, 2008 Listen, do you want a good amp? Something cheap, but playable with good tone and onboard effects? Go get yourself a Line6 Spider 15 watt amp for $99. You can find it at Sam Ash, Guitar Center I'm sure carries it, as does Musician's Friend or whatever. Seriously. I have one, and it's awesome, I paid $99 for it. You're not breaking the bank, and you're getting effects too in one package. Also...if you want to play louder than that, there's a Spider III available as well in a 4x12 package, but that's closer to $400 or $500 (I don't know what the price is exactly, that's either a little high or a little low). Quote Link to comment Share on other sites More sharing options...
BluefoxIcy Posted March 13, 2008 Author Share Posted March 13, 2008 Listen, do you want a good amp? Something cheap, but playable with good tone and onboard effects? Go get yourself a Line6 Spider 15 watt amp for $99. These are pre-amps I'm looking at, the first half of the amp stage (my amp uses a 12AX7 into an EL84, but 12AX7 into 12AX7 into EL84 can be done). That or the Roland Cube, both of which I was eyeing up before and might actually pick up still (after a few more things... sloooow spending schedule). I'm using a Valve Junior (love it, awesome overdrive, and I've got it to break up into a bluesy sound quite nice) but I'm going after replacing it with the Valve Junior Half Stack since the combo pounds on the tubes and makes an irritating rattle (and damages them!). I'll throw the BitMo TRIO mod on to get a bright/wide switch, which'll give me a setting that lets me pick up some screaming blues (I've heard it, it fucking rocks). http://demos.dovetailsystems.com/bruce/Bruce%20Hutcheon%20-%20Night%20of%20the%20Dogmen%2006.mp3 No pedals, no effects loops. Pure signal characteristic manipulation and overdrive. Quote Link to comment Share on other sites More sharing options...
Fray Posted March 14, 2008 Share Posted March 14, 2008 So is there anything fundamentally different between a guitar amp and a mic preamp? Or are they pretty much the same circuit? Quote Link to comment Share on other sites More sharing options...
1makes2 Posted March 15, 2008 Share Posted March 15, 2008 So is there anything fundamentally different between a guitar amp and a mic preamp? Or are they pretty much the same circuit? a guitar should go through a DI (direct input box) before hitting the mic preamp because the guitar is anywhere betwen 10 to 40 dB louder than a microphone signal. you can get a DI anywhere from 50$ to 660+ dollars so whatever you want. my friend got a pod6 guitar processer and its sick! he orderd one and they shipped him 12! he only paid for 1 so he shipped 11 of them back! i was pissed that he didnt give me one first. Quote Link to comment Share on other sites More sharing options...
BluefoxIcy Posted March 15, 2008 Author Share Posted March 15, 2008 a guitar should go through a DI (direct input box) before hitting the mic preamp because the guitar is anywhere betwen 10 to 40 dB louder than a microphone signal. Nice thanks for that. That preamp is actually a stupid op-amp on a starved plate tube (the tube has 50V instead of 300V on the plate, it does nothing) so yeah this is probably significant. A pure tube preamp won't really card, except that a guitar preamp might have a bigger input line resistor and/or smaller ground resistor (the signal in my VJ for example goes across 68k to the tubes, and 1M to ground, letting a few percents of the signal ground out; originally that 1M was 100k so uh yeah like 1/3 the signal was discarded, I threw in a 1M for better gain). Of course, the tubes overdrive FASTER with bigger signal in.... With a solid state device, you might just blow it or set it on fire (blow, pop, sparks, ignite if you're not lucky). Didn't know about the signal difference. Makes much more sense where the electronics would change from that. Quote Link to comment Share on other sites More sharing options...
SnappleMan Posted March 15, 2008 Share Posted March 15, 2008 These days all mic preamps are built to support both, guitars and mics. I used a tube preamp for some time, and I really liked it. Going 12AX7->12AX7->EL84 will not sound like you're hoping it would. They're not part of the same circuit, and so they work independently, what you want is to mod the amp for another 12AX7 tube, then they work in series or parallel and they thicken up the sound. Adding the preamp will only give you a gain boost. Quote Link to comment Share on other sites More sharing options...
BluefoxIcy Posted March 17, 2008 Author Share Posted March 17, 2008 Going 12AX7->12AX7->EL84 will not sound like you're hoping it would. They're not part of the same circuit, and so they work independently, what you want is to mod the amp for another 12AX7 tube, then they work in series or parallel and they thicken up the sound. Adding the preamp will only give you a gain boost. You're right. And that mod isn't actually any difficult to do.. it's also easy to switch in/out of the circuit and make it parallel or series (I had a rather gross and deranged idea on parallel tubes in this respect, involving a pot wired as a voltage divider to give disproportionate levels of signal to each tube; and each tube with its own vol pot). Quote Link to comment Share on other sites More sharing options...
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