Using a Pre-amp in a Guitar Tube amp as a Microphone Pre-amp

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rkaczano

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I have been researching good microphone pre-amps to feed into my interface (Steinberg UR28M) via Cubase 7. I want to warm up my voice and guitar sounds

Something just dawned on me. I have an unused Rivera 45w Chubster guitar amp. Can I use the pre-amp in this guitar tube amp as a microphone pre-amp?

SETUP:
I am recording using an SM57 on a MESA 4x12 cabinet. The microphone cable current feeds into my interface. Could I instead feed that microphone cable into the clean channel of my Rivera and then use the Line-out of the Rivera pre-amp and send the signal to a line-in on my interface. In effect I bypass the speaker of my Rivera using the line out. I think the line out is 8 ohm.

Effectively I am asking if I can use a good tube guitar amp as a replacement for a good microphone pre-amp. Or is does this create other issues?

Thanks
 
The input on your guitar amp is Guitar Instrument level, so you would have have to first change the Mic output to match.
That could cause some additional noise....but other than that, technically it could work, how it sounds is for you to find out. :)

Also, the Line out has nothing to do with your speaker Ohm rating.

Back in the day (like late '60s/early '70s) they use to take high-impedance mics and plug them into their amp channels for a cheap "PA/Guitar Amp" setup....some of those old amps even have Accordion inputs. :D
 
So to be clear, I have an XLR to 1/4 adapter for my SM57. Can I simply plug the adapter into the microphone and the then the Rivera re-amp, disconnect the Rivera pre-amp from its speakers, and run another 1/4 cable from the Rivera pre-amp into my interfaces line-in?

I am currently only using the Mic/Line/HiZ inputs on the interace (See URL below 1 & 2). For this configuration would I instead connect to the Line IN (See URL below 3 & 4).




Thanks
 
When Miroslav talks about changing the mics output, he doesn't mean the connection type.
He means the level of the signal, and probably impedance.

The signal generated by instrument pickups is significantly hotter than the signal generated by a microphone.
 
Unless you're looking for a real lofi sound, I'd give up on this idea. The tubes won't "warm up" anything.
 
Steenamaroo said:
When Miroslav talks about changing the mics output, he doesn't mean the connection type.
He means the level of the signal, and probably impedance.
Click to expand...

Right.

Track Rat said:
Unless you're looking for a real lofi sound, I'd give up on this idea. The tubes won't "warm up" anything.
Click to expand...

Agreed....how it will sound is more the issue than if it can it be done technically.
 
Ok thanks.

I was trying to save myself some money and thought I had stumbled onto a good solution.

I have been testing a rented Neumann TLM 103 against an SM 57. I don't hear a lot of difference when using the pre-amps in my interface (UR28M). Was wondering if doing so with better pre-amps might accentuate the differences. May go out and rent an UA LA-610 and see if this highlights anything.

Thanks
 
A 103 and a 57 should be a night and day experience.
I haven't used the 103 extensively, but I remember it being pretty pronounced in the highs.
Maybe renting something is a good idea, just to find out for yourself?
 
I say try it! Just use that adapter you've got and jam it in there. There shouldn't really be an impedance issue (most mic pres nowadays are higher Z than necessary for most mics to begin) and most guitar amps have plenty of gain to make up for the low input voltage of the mic. Frankly, a tube "preamp" stage is pretty much just a gain stage whether its intended for guitar or microphone.

So try it. At worst you've wasted a half hour and found out that it's too noisy or sounds like ass. It's possible, though, that it'll be perfect. You'll have a new secret weapon and when your album goes platinum, you can tell all the magazines and start a trend. Maybe they'll name the technique after you. :)

Edit - but double check to make sure it's actually a line output. If it actually says 8 Ohm, it would make me think that it's actually an auxiliary speaker output. You won't want to ply that directly into a line input, for fear of letting out the magic smoke!
 
That sort of thing has been done, but its more of an effects sound, than a sweet harmonic sound, you would get from a good mic pre.

Cubase 7 has very nice tube compressors that will warm up the sound. Have you tried those ? Also, make sure you have the latest version of Cubase, which is 7.06 right now, big improvements in the updates.

Do you have good monitors? You cant get an accurate account of those rentals on bad speakers.

For a real full lush harmonic sound cheap, try a Joemeek VC3

Joemeek VC3 Pro Channel Mic Preamp with Opto Compressor and Enhancer V2 | eBay
 
Rivera Pre-amp.webp
Picture of Pre-amp attached. Sorry it says 560 ohms. Its the output to the right of of the one with the cable going to the speakers.

Happy to explore VST options too. I want to understand this too!

Thanks
 
Yep, that's a Line Out alright! You might check the manual though. Looks like that's probably an attenuated and speaker emulated (filtered) output from after the power amp - meant to make the direct output sound more like the mic'd cab. This might work, but for a microphone which is catching a signal already filtered by a guitar speaker, it might not be ideal. There is that hole over to the right which is just straight out of the preamp which might work better for what you're trying to accomplish.

Neither of those outputs will hurt your interface, which is why I say just try it. Like I said, if it sucks it sucks. Either way, you learn something, right?
 
When my friend's PA amp blew I brought my Marshall over to see if it would work. Sure we got sound but it had distortion we could not get rid of even on the clean channel. To say nothing about the compression. They are designed for guitars not microphones and might a cool effect but not a quality preamp for vocals.
 
I still cant believe you cant hear a difference between the 57 and 103, even with your exsisting preamp! I just use the pre's on a 1641 and I can hear a huge difference between my dynamic and condenser mics.

Are you sure everything in your signal chain is ok??
 
dreib said:
I still cant believe you cant hear a difference between the 57 and 103, even with your exsisting preamp! I just use the pre's on a 1641 and I can hear a huge difference between my dynamic and condenser mics.
Click to expand...
While I can tell that there's a difference between the different mics that I have, I mean, they all sound different from each other, I can't tell the difference between a condenser and dynamic per se. The difference is in specific mics as opposed to their type. To me, anyway.
 
I suppose I can hear such a huge difference because my room is less than awesome?
 
grimtraveller said:
I can't tell the difference between a condenser and dynamic per se. The difference is in specific mics as opposed to their type. To me, anyway.
Click to expand...

Listen to the crispness and concentrate on the faster transients.

Also, to me, the mid-range of dynamics always sounds different....maybe a touch more nasally.
 
miroslav said:
Listen to the crispness and concentrate on the faster transients.

Also, to me, the mid-range of dynamics always sounds different....maybe a touch more nasally.
Click to expand...
I don't know what 'transients' sound like.
But the condensers are generally 'crisper'. I think of it as 'treble-y-er'.
 
The "attack" (initial "spike") of an audio signal. Like drum/percussive stuff or some instruments that have fast attack at the front of the signal....with condensers, becuase there is no moving coil, they pick those up better/faster than dynamic mics.
 
rkaczano




rkaczano,
I'm not sure if you were planning on unplugging your guitar combos internal speakers during this experiment or not, but if so: Don't because you can damage tube poweramp sections when they're operated without a speaker or resistive load attached :thumbs up:
 
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