Did an unscientific test on my preamp..

[Jay Jay]

I need Phantom power for some new condensers so I'm waiting for a DMP3 to arrive. I currently use an old ROSS 12 channel mixer for my mic pre's, inserts out to an M-Audio 1010. I figured the pre's in this cheap old mixer were pretty bad.

So, a little test.
I generated some white noise, spectrum analyized and saved the graph.
Sent the noise out of the 1010, through the input of the mixer, out of the (insert out) of the mixer, into a different channel of the 1010 and recorded it.
Again, analyized it, overlaid the graphs, and they were within 1 db of each other everywhere except for above 21KHz.
The ross dropped everything above 21KHz

Now, if the frequency responce if so flat, what do you gain from a better pre? I couldn't hear or measure any background noise on a -90db meter scale. Even the distortion numbers are low on the new cheap stuff.

So , what makes a better Pre, a Better Pre???????

 

[tubedude]

Last time I listened to a spectrum analyzer, I didnt hear anything at all.

The point isnt if its flat or not, its the artifacts it might produce and the clarity that makes the difference. The difference can be significant, other times its impossible to tell.

 

[regebro]

Now, if the frequency responce if so flat, what do you gain from a better pre?

Non-flat response. Which in fact is often what you want.


But as mentioned by others, there are a lot more to it that frequency response.

 

[chessrock]

Last time I listened to a spectrum analyzer, I didnt hear anything at all.

Yea, and to top it off, last time I listened to White noise I wasn't impressed at all. Sounded like a bunch of freakin' noise if you ask me.

 

[Robert D]

Yea, and to top it off, last time I listened to White noise I wasn't impressed at all. Sounded like a bunch of freakin' noise if you ask me.

I heard they're teaming up with Pink and renaming the band.

 

[Robert D]

Yea, and to top it off, last time I listened to White noise I wasn't impressed at all. Sounded like a bunch of freakin' noise if you ask me.

I heard they're teaming up with Pink and renaming the band.

 

[Jay Jay]

Yeah, very funny guys....

Anyway, am I thinking correctly that a mic pre isn't just about being transparant? It's more like a mic selection, where you would pick what would make the source sound good?

In thinking that, does this seem right?

Cheap pres' would just sound sh*tty due to poor components or design which would just give a bad sound. Behringer comes to mind from reading this board.

Something transparent, but good sounding, like the DMP3. (Because of reading here, a DMP3 is on its way)

The ART pres' add coloration with tubes. Not bad, just a different sound.

Mackies and higher end, are very clean and also have a distinct coloration.

I never thought much about the mic pre until I started reading this friggin board over a year ago. It was so much cheaper and easier when I didn't know anything about recording.......

 

[TexRoadkill]

All those pre's you just mentioned are still in the cheap range they are just not bottom of the barrel.

A good pre can have a noise floor of -120db or better and distortion ratings of around .0008. The ross is probably in the .0x range. They also can provide higher gain with less noise. Since you were feeding the mic pres a line level signal in your test they didn't have to add much gain and weren't really working very hard.

 

[chessrock]

A lot of what constitutes a good pre is how it "loads" the mic you're wording with (which has to do with impedence). Another is how uniformly it responds accross the spectrum at different volumes and gain settings. How it responds to transients is another (how quickly or how slowly and what colorations it might impart -- also how uniformly it responds to high frequency transients versus low frequency transients and at different volumes, etc. etc.).

White noise at a constant volume isn't a very meanifngful test in the real world.