Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: embotone on November 09, 2011, 12:35:32 pm
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I have a friend who has asked me to build him an amp. He would like an amp to play acoustic guitar through and be able to plug in a mic for vocals in a coffee house type venue. To complicate matters, he would at times like to use this for electric guitar. His tastes in electric guitar tones tend toward heavy, and to me, crappy sounding distortion. I don't think he is terribly discerning when it comes to electric tones. So, perhaps an amp where he could use pedals for his dirt. Or, a switchable gain stage on one channel of a two channel amp, one voiced for guitar and one for vocals.
My first thoughts are an AB763 type amp, with 2 channels. He doesn't want a heavy amp, so maybe a combo with a 15" Neodymium speaker, 40-50 watt range.
Any ideas out there? Not really sure how to voice an amp for vocals. Any suggestions or comments regarding speaker selection? I've never used, or knowingly listened to, any neo speakers.
Thanks for any help.
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design this thing around a vintage hi-fi circuit and consider using a crossover and tweeter. have him bring his favorite od pedal for rockin out.
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acoustic guitar players can be unrealistic in their want for amplifiers and preamp's, IMHO. They want their guitar to sound like Kottke's "6- and 12-String", Dylan's Its alright Ma, and Steve Miller's Take the Money and Run with the turn of the knob, but they have transducers or piezos, a general purpose PA, and outdoor patio instead of a ribbon mic and killer mic pre's behind it in a studio.
add voice to it? good luck.
a single amp that can do all of those well? maybe have him buy a purpose built solid state amp for accoustic/voice, and you can build him a 6watt champ that he can mic when he wants to Joe Walsh it.
If he has a sound hole pole piece magnetic pickup, you might be ok with an electric guitar amp (depends on his desired sound)
If all he'll ever want out of it is a solo act in a coffee house, maybe a 2x6v6 10W Princeton with 2 channels?
If you have a amp you've built, have him play accoustic through one channel and a mic through the other.... see if he is still interested...
Also, should you move forward with this, you'll probably want to design the voice channel with a specific microphone type in mind (the kind he uses). mic output levels vary (2mV to 1V!), an SM58 has an XLR balanced output @ 150ohm and a level of -51.5 dBV (0.002v rms), depending on the mic... think about a input transformer, and a dedicated channel that you can amplify the vocals up to loud level without all kinds noise and preamp-distortion. and hope it doesn't squeal like a banshee with the slightest feedback.
If he still isn't dissuaded and you aren't either... then lets do this..!
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I think my first chore is to convince him to forgo the vocal/mic channel. It would be an fun project, though, building a mic preamp into an amp. Have not done that before.
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My leanings are exactly the same as yours: An AB763 Deluxe, maybe with 2-channels reverbable. Little cleaner, more oomph? Change to Vibrolux power.
Though I am favorably disposed to (won't use the term "biased" ha ha) towards blackface Fenders, I think that makes sense for the wants you described.
By the way, have you considered a Fender Acoustisonic? Yeah, I know, solid state. Also $400 or so. This is an important consideration and if I'm off base, I apologize: Are you supposed to hand-build an amp that would normally sells for over a grand in custom, hand-built mode >>AND SELL IT TO HIM and become infinitely responsible for servicing and "tweaking" it to his liking FOR $400<<< when a $400 amp might be the correct answer?
Just asking.