silly question

M

mustardeer

New member
sorry i'm still a newbie.

i got a Samson SX1200 amp and an EV ND767A mic.
Can i plug it in without a mixer? I've tried and i get no sound.
The Amp is correctly connected to a pair of working speakers.

I also have a DMP3 preamp laying around, would it make a difference? Logic tells me no.
 
The signal level coming straight out of the mic will be too low for the amplifier's inputs. Use your DMP3 (to serve the same purpose as the preamps in a mixer) to amplify the signal up to line level (what the amplifier is looking for), then you should be fine.

I think...
 
Physically, yes you can hook it up and it won't hurt anything. But, technically speaking, you should not.

Due to the ohm load and voltage mismatch there may not be enough signal strength to drive the circuitry in the amp. It would be mostly unusable that way. In other words, if you turned up the amp volume to max, the volume would still be very low.

You see, microphones typically put out a very weak signal, almost too weak to be usable. Pre-amps like your DMP3 are designed to boost that signal up to a more healthy range. (Mixers do the same thing.) When the meters on your DMP3 are bouncing between 50% and 100%, then your power amp will become more productive.

The volume knob on your power amp should always be set at max. The volume should be controlled by the preamp or mixer.
 
oh nice, thanks, i'll try plugging in the DMP3 at the band rehearsal later today, will let you know if it works. Sounds exciting! 'Cause those Mackies are like 300-400 bucks.
 
While not ideal, you can get impedance adapters for about $20 that allow you to plug a low impedance (XLR type) mic into a high impedance 1/4" jack.
 
just got back from rehearsal.
amazing sound!! i was very surprised. thank you!
i wonder if i should bring the dmp3 to live gigs at a real venue. probably not.
 
mustardeer said:
just got back from rehearsal.
amazing sound!! i was very surprised. thank you!
i wonder if i should bring the dmp3 to live gigs at a real venue. probably not.
Click to expand...

Well Mustardeer, that's your call. But you need to understand this- Almost all mics put out a "mic level" output, which is way lower than "line" level. Most mics of the last 30 years or so are looking for a low impedence input, today's standard mic input, and use a 3 pin XLR connector. Some really old mics, and a few oddballs, such as the Green Bullet harmonica mic, are meant to plug into a high impedence instrument (AKA high-Z) input, such as a guitar amp. There is also such a thing as a "line level" mic, that has a built in preamp, and puts out a line level signal, such as Shure SM82. That is *very* unusual.

A power amp, like your Samson. is intended to take a line level signal and provide a far more powerful signal designed to drive speakers. All (normal) mics need a preamplifier to raise the mic signal to line level. A mixer is just a bunch of preamps (usually cheap ones), with a bunch of routing options, so you can send various signals, or combinations of signals (sub groups) to various locations. Some mixers are "powered"- in other words, they have a power amp built in. Some speakers are "powered" or "active", meaning that they have a power amp built in. Some active speakers also have mic inputs, meaning that they have a preamp and a power amp built in.

Any time you use a mic to make live sound, you have to have a mic, a preamp, a power amp, and a speaker, in some combination. So you can use the DMP-3 for gigs, or a mixer, a power amp and a speaker, or a powered mixer and a speaker, or an unpowered mixer and an active speaker, or a powered speaker with a mic input. It doesn't matter *where* the components are, as long as you have them all, the components match, and you don't duplicate any of the components. In other words, plugging your power amp into a powered speaker would be *very* bad.

One other thing worth noting- Not all line levels were created equal. First, there is -10dBV. Think of this as "consumer" line level. That's what most home stereos use, and is usually transmitted by RCA jacks. This is what you would get from the "tape out" jacks on a mixer. Then there is +4dBu. Think of this as "professional" line level. This is what your Samson is looking for, as well as most PA components. You could plug a -10 line level signal into your Samson, but it would be noisy, and require you to crank the Samson a good deal more. You'll notice your DMP-3 has a Hi/Lo switch. Essentially this changes the line out from -10 to +4, so it should work better to use the Hi setting, and turn the DMP3 down a bit. Should you bring the DMP-3 to gigs? It depends on what other preamps you have available. You have to have one somewhere in your signal chain. Hope this helps-Richie
 
mustardeer said:
just got back from rehearsal.
amazing sound!! i was very surprised. thank you!
i wonder if i should bring the dmp3 to live gigs at a real venue. probably not.
Click to expand...

What type of music are we talking here? That you only need one mic.
And what did you use the mic. for at rehearsal
 
Richard Monroe said:
You'll notice your DMP-3 has a Hi/Lo switch. Essentially this changes the line out from -10 to +4...
Click to expand...

Are you sure about that? It is my understanding that this is a "gain range" switch to be used to adjust gain needed to amplify the incoming signal level from a mic or instrument (as the output from these devices varies). It is not a switch that converts the nominal output level (-10dB to +4dB) signal that is being sent to another piece of equipment.
 
Thank you, TDukeX. I stand corrected. It's acyually like pre and post gain controls. YTo bad. It would be useful if the DMP-3 could put out a -10 signal. That's what O get for making asumptions.-Richie
 
You must log in or register to reply here.
Back
Top