Does a 'really expensive mic pre' make THAT much difference???

[chrisdee]

Re: Does a 'really expensive mic pre' make THAT much difference???

Only if it's in great condition and the performer and engineer knows how to use it.

But of course a new $5000 dollar mic is most probably going to sound much better than a $50 dollar mic in the same recording settings.

[Pinball Wizard]

Originally Posted by PTUser NYC

API mic preamps are known for high slew rates.

I believe there may be a typo here. Although modern API equipment may be good, classic API equipment is know for low slew rates.

Here is a mid-vintage spec sheet for the 2520 'brick' which was the basis for most of the classic equipment.

http://www.classicapi.com/catalog/im...ocs/2520-1.pdf

Note the 3 volt/microsecond spec.

Older 2520s were even slower, speced at 1.5 v/us

These are really poor numbers. In all fairness, they are minimum numbers that production units would exceed, but still they are very slow by even the standards of the later 1970s.

So what gives? Why does something that measures so bad sound so good? Here is one explanation that I have heard......

In typical early opamps, the slew rate was limited by the inability of the transistors to supply enough current to quickly charge & discharge the circuit capacitances at high frequencies. The transistors went into a kind of current limiting and produced distortion....some of which obnoxiously fell out at lower frequencies than the original exciting frequency. The API designers didn't have that limitation. They were using relatively large transistors with MUCH more current capability than in a small IC opamp. They did, however, fear the problem of high frequency energy affecting stability and deliberately throttled down the speed of the brick. This deliberate slowing was done not by pushing a device beyond it's limits but by more civilized bandwidth control. Hence the 2520, while slow did not suffer from the terrible SID & TIM of older IC OPAMPS.

Please understand that what I have posted here is an urban legend. I do not know if it is correct. It is just a possible explanation that I have heard to explain the lack of correlation between slew rate & quality in 2520s.

Don't think that I am negative on API. I have been a fan since the early 1970s & have purchased two of their consoles and a slew (get it ?) of their cards. I own 2520s with Huntington, Melville, Studio systems division, and blank labels. I have experience with Melcor & RCA brick amps. ...and I own one of the elusive RCI amps. I love the stuff and highly recommend it....but not for high slew rate.

further reading: http://waltjung.org/PDFs/SID_TIM_TAA77_P1.pdf
note this was published in 1977, long after the 2520 was designed

[albee1952]

Just goes to show that a spec sheet doesn't have the final word. And no mic(regardless of price) is perfect for everything, so it stands to reason that preamps "suffer" the same thing. That's why its best to try to cover a few bases so you have choices. That's why I have a pair of Five Fish API 312 clones and a pair of Vintech 1073 clones. They really are different "flavors" and offer solid options to the Focusrite ISA pre's that are mostly invisible. And don't ignore the impedance adjustments on some as that can give even more options out of 1 preamp. Having said all that(and yes, I suffer from G.A.S. as much as the rest) I still find it hard to point out any hit that became a hit because of the mic, or preamp(but that won't stop me from buying a Helios or Telefunken).