is it me or is this full of alot of crap?

[shortedaman]

http://www.kellyindustries.com/preamps.html


i read what this guy had too say and while he was correct about alot of things, i feel as if he was also badly mistaken on others. am i right or am i wrong? thanks

 

[SouthSIDE Glen]

i read what this guy had too say and while he was correct about alot of things, i feel as if he was also badly mistaken on others. am i right or am i wrong?

Whether you're right or wrong depends upon just which things you think he was correct or mistaken about.

One thing is fir sure, that is one poorly written article. It's hard to tell at times whether what he writes is wrong because he has it wrong in his head or because he doesn't know how to write well in English.

G.

 

[mshilarious]

I'll have a go:

A microphone preamp is used to increase the gain of a microphone.

Semantically wrong, a preamp is used to increase the signal level of a microphone. "Gain" is the amount of that increase. The microphone neither knows or cares how much gain the preamp is adding, so the "gain" of the microphone is unchanged.

The mic preamp is really only the input section of mixer, usually called an ‘input channel’.

OK.

They are required when using low impedance microphones, usually condenser mics, because these mics don’t have enough voltage to connect directly in to a mixing consoles input.

Sorta, although the voltage level of a dynamic mic is generally far below that of a condenser mic.

There are some mixers, line level mixers for example, that don’t have mic inputs at all and a preamp is required to get the mics output signal to line level. Mic Preamps can be found in mixers, recorders, and other devices that use a microphone. There are also mic preamps that operate as stand alone devices while others are used in combination with Analog-To-Digital converters to create an Audio Interface or sound card as they were originally called.

OK.

The preamp circuits are the first thing the output of an audio signal sees before anything else.

Output of what audio signal? That should read "output of a microphone".

These signals are very small, tenths of a millionth of a watt.

Maximum power transfer (which nobody really cares about anymore) is achieved at matching impedance (which is a usually a bad idea), for a typical dynamic mic that might be 2mV/Pa into 250 ohms, using Ohm's law:

I = V / R
I = 2mV / (250 source + 250 load) = 4uA
P = V * I
P = 2mV * 4uA = 8nW

But a condenser mic at 20mV/Pa:

I = V / R
I = 20mV / (250 source + 250 load) = 40uA
P = V * I
P = 20mV * 40uA = 800nW

OK, so somewhere in the millionth to billionth of watt range, I'll buy that.

The preamp will boost the gain by 50 to 60 dBu or more.

Point of order: dB is a comparison between two figures. The "u" part is an absolute reference. When you subtract two signal levels, the absolute drops out, so gain is simply always dB and not dBu.

The idea is to get the mics output level to that of the other audio signals where they are then mixed together in a mixing console. The output levels are usually between -20 dBu to +4 dBu.

OK.

The design of a preamp is of importance in that this is where a large amount of noise and distortion can be generated. They should have both low distortion and self-noise specification which you can find in specs sheet of the preamp.

Sure.

The preamp should have enough gain to bring the output up to your current mixing boards’ input level without overloading the microphone or the mixer’s input.

The preamp cannot overload the microphone with gain, see above.

Lately there has been a number of mic preamp that allow you to change the input impedance (Mackie 800R for example) to match that of the microphone. Usual input impedance of condenser mics range from 50 to 200 ohms and can operate at up to 10 times this amount, 500 to 2000 ohms with no problem.

That's backwards. Condenser mics don't need or want to be loaded down with a matching impedance. So it should read that condenser mics can operate down to their source impedance (although still generally not a good idea, as distortion will increase in the microphone circuit and signal level will drop), and are happier at any higher value (which for a condenser mic is limited by the phantom supply resistors if nothing else).

NOTE: Mic preamps can also be used to amplify the signals from guitar pickups. This is somewhat of a special case for the preamp in that it operates more as an impedance converter which provides more current to the signal as the voltage from guitar pickups are already at line level used by most mixers.

Close enough. Consider that all amplifiers are exactly that, devices that add current (amps). That can be translated into voltage gain by forcing that current through a resistor (according to Ohm's Law).

We like to give amplifiers clever different names, like "impedance converter" or "mic preamp", but at the end of the day they are all just devices that can supply more current than they are fed from the signal input.

Unless the mixer or input provides a high input impedance circuit made for guitars the preamps found on most mixer will overload the output of the guitar pickups and sound very thin and weak.

Yeah, instruments do need a high input impedance because they have a high output impedance. The tone will change beyond a simple signal loss as you'd get with a heavy load on a condenser mic because the instrument pickups have a complex source impedance, so that loading has different effects at different frequencies.

The gain of the preamp can be changed using the ‘Trim’ control which lowers the gain.

Some trim controls change gain in the amplifier, some just attenuate the amplifier's output. Depends on design.

If the preamp’s input is set too hot there will be added distortion and noise to the signal.

Distortion yes, noise usually is relatively less at higher gain rather than lower gain. Common misconception. However that does you no good if you are driving the amp into distortion.

Also if the gain is too loud the circuit may start to oscillate.

A properly designed circuit should never oscillate. At high gain bandwidth should be limited to prevent that.

If the signal is already loud enough then it’s best to just bypass the preamp and go directly in to the ‘line level’ input. The line level input is what follows the mic pre amp as this is what the preamp is made to do.

OK.

Types of Connections and Phantom Power:
Most come with XLR inputs and outputs while some come with both XLR and TRS inputs and outputs. Some mics require an external electrical charge which is provided by the preamp’s Phantom Power Circuit.

Phantom should be thought of as current rather than just a charge. The microphone capsule requires a charge, but its amplifier circuit indeed needs a reasonable amount of current.

Care needs to be taken to be certain the microphone you are using requires phantom power. Condenser microphones usually require phantom power but some contain their own power in the form of a battery (electret condensers)

Overgeneralized, but otherwise OK.

Connecting an unbalanced dynamic mic to phantom power will probably destroy the mic. Dynamics that are balanced (XLR) should be ok if connected to phantom power but it’s not advisable. Theoretically the power should result in ‘zero’ DC voltage across the mic elements coil but again I wouldn’t use a dynamic mic with phantom power enable.

Overcautious; the "belt and suspenders" approach. Practically no professional dynamic mic will be damaged by phantom. Ribbon mics can be in unusual situations.

Types of Mic Preamps: Solid State and Tube
There are basically two types of mic preamps but there is also some that go around the definition. Solid State Preamps use either transistors or op amps (small integrated circuits with a number of transistors) to amplify the audio signal.

An opamp is not necessarily a transistor IC, although that is the most common implementation. An opamp is simply a circuit topology. There are discrete transistor opamps, and if you go nuts you can build an opamp out of tubes.

These are generally meant to be more transparent or clean than a tube preamp. Solid State preamps are usually more resistant to noise including their own (self-noise). Because of this transparent quality solidstate preamps can have a sterile sound to them and lack a more definitive sound that tube version.

Tube preamps on the other hand are usually more expensive especially if you are trying to get a very low noise one. Each manufacturer’s preamp has its own sound because they color the sound. The trade off here is increased noise but great tone and a more natural and musical audio compression that occurs with tubes. Many studio engineers prefer tube base preamps over solid state ones but it really a matter of apples and oranges.

Sort of opinion, I'll leave it alone.

There are some preamps that use a solid state preamp stage and then pass the signal through a tube. The tube circuit has a drive knob that allows you to add more or less of the tube sound. This technically speaking is a solid state preamp.

No, technically speaking it is a hybrid preamp. It may be a marketing gimmick, but if the signal passes through the tube, then the tube is an active element in the circuit, for better or worse.

Today there are many makers of mic preamps. This is similar to number of high end guitar amp manufacturers where each one offers something a bit different. The cost of some of these preamps is somewhat excessive for the average musician which puts them out of reach for most musicians.

I'll agree that there are plenty of excessively expensive preamps.


Overall, I'd give that a B-/C+

 

[TheChikenMaster]

John why dont you post a proper explanation for us illiterates, please.

 

[mshilarious]

John why dont you post a proper explanation for us illiterates, please.

It really doesn't need to be complicated. A mic preamp is a device that primarily provides voltage gain, which is required because microphones have an output level from around -30dBV/Pa on the high end to -60dBV/Pa on the low end, and line level is roughly 0dBV.

The most important characteristics of a mic preamp are low noise and low distortion. The maximum gain is a relatively unimportant specification compared with low noise. A mic preamp with -130dBV input noise and 40dB of gain is much more useful than a preamp with -100dBV noise and 80dB of gain--the amp with low noise can be fed into another gain stage if required, but there is no cure for the noisy amp.

The circuit topology of the preamp is not important if the designer is able to achieve their design goal. Mic preamps usually provide phantom power, which is required for most condenser mics.

As I said, that dude got it mostly right, just made a number of semantic errors.

 

[SouthSIDE Glen]

I think Jon's being a bit kind to the author; that is one horrible article in my eyes. It rambles all over the place to the point of confusing the ones who need such an article the most, i.e. the newb; it makes no point and actually explains very little. And the seemingly random collection of facts that it does present are often misleading or incomplete. Does nobody have editors anymore?

A microphone preamp is used to increase the gain of a microphone.

Wrong. It's used to increase the signal level that comes out of a microphone to nominal line level voltages.

The mic preamp is really only the input section of mixer, usually called an ‘input channel’.

Wrong. It is *part* of the input section of a mixer, but to call it the input section would be tantamount to calling the phono preamp "the input section" of an integrated receiver. Additionally, the wording makes it sound like the preamp itself is called "the input channel", or is at least ambiguous about that.

Additionally, mic preamps are not *just* part of mixers. They are also stand-alone devices or part of integrated interfaces or rack mount channel strips. He does allude to interfaces later; but that simply invalidates this statement.

They are required when using low impedance microphones, usually condenser mics, because these mics don’t have enough voltage to connect directly in to a mixing consoles input.

The relative impedance of the microphone is irrelevant, as they are almost always going to have a lower output impedance than the input impedance of the preamp anyway. And they are going to be needed with any microphone, regardless of it's impedance and regardless of it's diaphragm design. There is nothing special about condensers here; they are also needed for dynamics and ribbons. In fact your average ribbon or LDD is going to require more preamplification than your average condenser.

There are also mic preamps that operate as stand alone devices while others are used in combination with Analog-To-Digital converters to create an Audio Interface or sound card as they were originally called.

Once again, while true, this negates the whole first half of the paragraph which wrongly defines a mic preamp a the input section of a mixer.

And, while the author is far from alone in this usage, I have always been bothered by the use of the term "sound card" for an external integrated interface. Let's stick to using "sound card" to describe an internal PC circuit card, shall we?

The preamp circuits are the first thing the output of an audio signal sees before anything else.

As Jon pointed out, there is no such thing as "the output of an audio signal". This probably is meant to read,"the output of a microphone". Again, where's the editor?

These signals are very small, tenths of a millionth of a watt. The preamp will boost the gain by 50 to 60 dBu or more.

Technically correct, but who talks about microphone signal levels in terms of wattage? The gain is in dB, not dBu. And since the dB gain is typically measured in terms of voltage and not wattage, the mix of measurements here is non sequiter, even if the numbers are basically correct. An amazing example of one statement that can be technically kind of correct and still be wrong three different ways.

The idea is to get the mics output level to that of the other audio signals where they are then mixed together in a mixing console.

The end of paragraph 2, and finally the first sentence that makes sense and carries truth.

The output levels are usually between -20 dBu to +4

And then he blows it by adding this on. While those numbers are in the right ballpark, the number of tracks I have received where the signal exiting the preamp far exceeded +4dBu are (rightly) far greater than the ones haven't.

I would go on, but Jon covered much of it already, but in a much kinder way, and the fact is that I am only two paragraphs into that debacle of a an article and I am already creating a post longer than the illiterates here will bother reading.

But the fact that in two short paragraphs the website has managed to create so much red penciling, and the rate of red penciling continues the same through the rest of the article, should make the point.

Information wants to be edited for quality.

G.

 

[TheChikenMaster]

now I always acknowledged that the preamp brings the mic level to line level and that it is necessary. What does this mean technically speaking, and Why does it work this way?

 

[SouthSIDE Glen]

now I always acknowledged that the preamp brings the mic level to line level and that it is necessary. What does this mean technically speaking, and Why does it work this way?

The main purpose of a "line level" is to provide a ballpark voltage area (i.e. somewhere around line level, give or take a few volts) around which the equipment is designed to properly operate. You have to make sure you're not going to blow up your EQ or your compressor or whatever by sending it too much electricity as a signal, and that you're not going to render it ineffective by just sending it a trickle of a signal that it's not designed to handle properly. And you also want to make sure there's a signal level for which the devices are designed to work at with the least amount of noise and distortion. So, standards were set to say that a fully-modulated signal should be calibrated to a specific voltage (in this case +4dBu, or about 1.23 volts), allowing the guys who build the gear to build stuff that works at those standard levels

The catch is that while microphones turn sound waves into electricity, they can only turn them into a relative trickle of electricity. An amplifier is needed to boost the trickle signal of a microphone up to the standard line level voltages that the rest of our gear is designed to work with. This amplifier is called the microphone preamp.

BTW, it's called a preamp instead of an amp only because historically it was meant to differentiate the preamp from the main amplifier that actually drove the loudspeakers.

G.

 

[TheChikenMaster]

Thanks that was very informative.

 

[TheChikenMaster]

maybe the guy wrote dbu to sound somifsticated

 

[NYMorningstar]

The relative impedance of the microphone is irrelevant, as they are almost always going to have a lower output impedance than the input impedance of the preamp anyway. And they are going to be needed with any microphone, regardless of it's impedance and regardless of it's diaphragm design. There is nothing special about condensers here; they are also needed for dynamics and ribbons..

In trying to keep it short for us illiterates, can you tell us how you match your microphones to preamps? When selecting a mic preamp don't you want to know to what degree the preamp's noise degrades the noise of your microphone?

 

[SouthSIDE Glen]

In trying to keep it short for us illiterates, can you tell us how you match your microphones to preamps? When selecting a mic preamp don't you want to know to what degree the preamp's noise degrades the noise of your microphone?

The shortest, simplest answer is "don't worry about it" . It's not easy to find a really horrible mismatch these days, impedance-wise.

A slightly longer, and maybe a little better answer, is that the rules of thumb typically say that the input impedance of the preamp should typically be somewhere between ~5x and ~10x the output impedance of the microphone. There have been loooong Gearslutz-style debates about exact numbers that I'm not interested in, but that's the generally accepted ballpark range.

In general (with heavy caveats depending much on the quality of design and construction of the preamp) lower impedance preamps will tend to emphasize the peaks and valleys of the microphone's frequency response as well as emphasize overall high frequency response. Conversely, higher impedance preamps tend to flatten out the mic's frequency response a bit. And because the higher resistance of the higher impedance preamp causes a higher voltage pressure, less further amplification gain is needed to hit line level.

A longer yet answer is that if you're really worried about it, there are a number of preamps out there these days that offer variable input impedance; basically an extra knob that lets you change the preamp's apparent input impedance. Again, arguments abound as to just how much of a difference this actually makes to the sound. My own experience (which is admittedly a bit limited on this specific point) is that it depends upon the both the mic and the preamp as to just how little or how much the variable impedance will change the sound; there's no real predicting the result with any given combination.

The best answer of all IMHO is to worry far more about matching the microphone's sensitivity spec to the preamp's maximum gain spec. The sensitivity spec is usually measured in weird-looking decibel units called dBV/Pa. As a general rule of thumb, you'd want the maximum gain on your preamp to be *at least* as many CLEAN dB of gain as the negative dBV/Pa sensitivity spec on the microphone. For example, if you have a mic rated at a sensitivity of -50dBV/Pa, you'd ideally want a preamp capable of providing comfortably at least 50dB of clean amplification. Short of that you may (despite what some may claim) drive the preamp into extra noise in order to get your mic signal up to standard recording levels. There are workarounds, such as using two preamps in series, or simply recording at a lower level, but I'd recommend those only as last resort choices.

BTW, Jon (mshilarious) has an excellent couple of articles on reading microphone specs on the IRN website. You can find Part 1 here, and find Part 2 here. Highly recommended reading for those interested in this stuff.

HTH,

G.

 

[NYMorningstar]

. My own experience (which is admittedly a bit limited on this specific point) is that it depends upon the both the mic and the preamp as to just how little or how much the variable impedance will change the sound; there's no real predicting the result with any given combination.

I can't agree with you because there is a way and I'll try to keep it short
Here's the 2 step, the charts are below.


Step One: Evaluating Input Overload Compatibility
1.Locate the microphone Sensitivity rating on the mic data sheet.
2.Find the Maximum SPL from the mic data sheet.
3.Using Table 1, find the microphone Sensitivity rating down the left side.
4.Find the Maximum SPL rating along the top of Table 1.
5.Move right along the Sensitivity rating row and move down the Max SPL rating column until they intersect and note the number -- this is the microphone's maximum output level expressed in dBu.
6.From the microphone preamplifier's data sheet find the Maximum Input Level (in dBu).
7.Compare the mic's maximum output level obtained from Table 1 against the preamp's maximum input level obtained from its data sheet to determine compatibility.
Example Using Sample Data Sheets
1.Microphone's Sensitivity rating is 20 mV/Pa.
2.Microphone's Maximum SPL rating is 130 dB.
3.Table 1 shows the Sensitivity row marked 20 mV/Pa shaded.
4.Table 1 shows the Maximum SPL column for 130 dB shaded.
5.The intersecting point is at 4 dBu -- this is the maximum output level of the example microphone.
6.The MS 1S Mic Stage data sheet(from a Rane MS 1S Mic Stage preamplifier) lists the Maximum Input Level as +10 dBu.
7.Since this mic's max output level is +4 dBu and the preamp can handle +10 dBu, then this mic will not overload this preamp (when set for minimum gain).

Step Two: Evaluating Noise Performance
Dynamic Mics
1.Find the impedance specification on the data sheet (use "actual" instead of "rated" if given the choice).
2.Use Table 2(look at post#15) to find the Output Noise in dBu, A-weighted, by finding the closest impedance listed.
3.Find the EIN (equivalent input noise) in dBu rating on the preamplifier's data sheet.
4.Reduce the preamp's EIN by 5 dB to approximate A-weighting.
5.Compare the two to see if the proposed preamplifier degrades the mic noise appreciably.
Condenser Mics
1.Find the Noise rating on the microphone date sheet (this is stated as Equivalent Noise Level, Self-Noise, Equivalent Noise SPL, or Noise Floor), expressed in dB SPL, A-weighted.
2.Locate the microphone's Sensitivity rating on the data sheet.
3.Using Table 3, find the microphone Sensitivity rating down the left side.
4.Find the Noise rating in dB SPL, A-weighted along the top of Table 3.
5.Move along the Sensitivity rating row and move down the Noise column until they intersect and note the number -- this is the output noise converted to dBu, A-weighted.
6.Find the EIN (equivalent input noise) in dBu rating on the preamplifier's data sheet.
7.Reduce the preamp's EIN by 5 dB to approximate A-weighting.
8.Compare the two to see if the proposed preamplifier degrades the mic noise appreciably.
Condenser Microphone Example Using Sample Data Sheets
1.Microphone's Equivalent Noise Level is 14 dB SPL, A-weighted.
2.Microphone's Sensitivity rating is 20 mV/Pa.
3.Table 3 shows the Sensitivity row marked 20 mV/Pa shaded.
4.Table 3 shows the Noise column for 14 dB SPL, A-weighted shaded.
5.The intersection point is at -112 dBu, A-weighted: this is the output noise of the microphone.
6.The MS 1S Mic Stage data sheet lists the Equivalent Input Noise as -128 dBu (no weighting).
7.Reducing this by 5 dB yields a preamp EIN of -133 dBu, A-weighted.
8.The difference between the microphone’s output noise of –112 dBu A-weighted and the preamp’s EIN of –133 dBu A-weighted is –21 dB so the preamp’s noise will not degrade the performance of the mic.
TABLES 1 & 3:

 

[SouthSIDE Glen]

I'm still digesting those charts; I haven't figured out what maximum SPL is supposed to have to do with the subject yet. But it'll have to wait, it's time for me to go get the Super Bowl food before the game.

But I will say that what I was saying was there was no way to reliably predict just how a variable impedance input would affect the sound of any given microphone. While there are general electrical trends, whether it'll make any given mic sound better, worse, or indifferent is not entirely within the realm of science.

G.

 

[NYMorningstar]

Sorry, didn't realize a post can take only 2 tables. Here's Table 2

 

[mshilarious]

NYM's analysis is correct and not that difficult if expressed a bit more simply:

Maximum mic output = (max SPL - 94dB) + sensitivity

If sensitivity is listed in mV/Pa rather than dBV/Pa (an annoyance if you ask me):

Maximum mic output = (max SPL - 94dB) + 20 * log (mv/Pa)

The preamp's maximum input level should be higher than that figure. This is rarely much more than +5dBV or so, so that shouldn't be a huge problem.


Noise (condenser mic):

Preamp should ideally be 10dB below the mic's output noise:

Mic output noise = sensitivity - 94 + self-noise

Compare with the preamp's equivalent input noise specification. If there is no such specification, consider selecting a preamp from a manufacturer that lists a proper specification.

For dynamic mics, the preamp's noise is the noise floor, practically speaking, so you just want preamp input noise as low as possible.

It isn't necessary to "match" microphones in that respect; you just select a preamp that has low noise, low distortion, ideally low minimum gain and high headroom. There are plenty of such amps on the market; reject the ones that fail one of those criteria.


None of that has much to do with input impedance. For condenser mics, you really never want a low input impedance. The typical 1K or higher is fine. If you lower the input impedance you will generally just degrade the signal.

For dynamic mics a lower input impedance can have a useful effect, but if your preamp doesn't have that feature you can always solder a 600 ohm resistor into a cable connector.

 

[SouthSIDE Glen]

Ok, now that I've had a chance to re-read ad pay attention, I see what's going on. Yeah, NY, your tables and procedures do make sense. For the less literate following us, the simplified points behind them are to a) not pick a preamp with such low input voltage expectations that the mic is actually too hot for it, and b) not to pic a preamp that's actually noisier than the mic itself. Both of which make sense.

What threw me off was that they were a opposing reply to my comments about input impedance, which was really talking about a different flavor of issue altogether. The two different analytics do not conflict with each other as they are analyzing quite different aspects of "compatibility". It's like saying that an analysis of the color of a shoe is wrong because the size of the shoe is different.

I agree with Jon that in this day and age it's kind of difficult to find a preamp that is too anemic for the microphone in terms of minimum input level and self-noise as long as one pays attention to such things. Of course if one is talking about some El Cheapo $99 integrated interface or $50 preamp, all bets are off - especially if the published specs are themselves wanting for detail. But I'd assume that if one is going to dive this deep into the subject, that they're probably looking for something more esoteric than the entry level consumer stuff.

Where I do see common problems (based upon this board's traffic), however, is in potential mismatches of sensitivity vs. gain. It's not uncommon for people to recommend a nice LDD like an RE20 or or SM7b, or even a ribbon, to someone running something like a Lexicon Alpha or mAudio Fastrak for their preamp. When you have a mic that requires some 60-70dB of gain from the preamp to get the signal up to nominal line level, a preamp with 45-55dB of maximum gain is probably going to leave the user somewhat wanting in the signal level and signal dynamic range departments.

G.

 

[mshilarious]

I am not so sure that gain is always that important anymore. Traditionally, if you're running through a mixer or feeding a compressor, you will pay a noise penalty if you don't get up to line level in the preamp stage. This is because following stages might be relatively noisy, as they are assuming they're getting the line level they specified.

But going straight from preamp into modern converter, I don't think it matters too much. The rule is the same: you want to get the mic/preamp noise level at least 10dB above the converter noise level. Let's say you are running a dynamic mic into a -130dBV equivalent input noise preamp, and your converter has 110dBV (fairly modest these days) of dynamic range, and its maximum level (0dBFS) is +15dBV. Thus, its noise floor sits at -95dBV. How much gain is required?

-95 + 10 - (-130) = 45dB.

True, your operating level will be low and you won't get anywhere near 0dBFS. In fact, you might be more like -30dBFS. But that doesn't matter, you can follow conversion with a digital gain change and suffer no signal-to-noise penalty.

Now, if the integrated preamp/interface has poor input noise performance no amount of gain is going to help. But the 55dB gain spec wouldn't scare me per se.

 

[SouthSIDE Glen]

I am not so sure that gain is always that important anymore. Traditionally, if you're running through a mixer or feeding a compressor, you will pay a noise penalty if you don't get up to line level in the preamp stage. This is because following stages might be relatively noisy, as they are assuming they're getting the line level they specified.

But going straight from preamp into modern converter, I don't think it matters too much.

I don't believe that just because there's an increasing number of newbs with nothing but a cheap integrated interface that one should consider it less of an issue. There's a few of reasons I believe that:

First, there's also an increasing number of users that *do* run more real analog chains before the converter for which your first paragraph applies. But frankly, we just don't see/hear from them as much in forums like this because they just don't have the number of questions that the virgin newb with just the Pod X3 has.

Second, for those newb users with just the little interface, you KNOW that 8 times out of 10 they're going to want to, rightly or wrongly, push their levels regardless of their equipment specs. They are going to encounter more - and more obvious - problems because of anemic gain than they will with finding a microphone that actually too hot or too clean for the pre. The fact that it's their fault for feeling they have to use all their bits is a separate problem which we are addressing here all the time, but it certainly doesn't help to make it even more of a problem by advising it's OK to mismatch the sensitivity/gain equation.

Third, even if you do record the signal at lower digital levels, which in and of itself is fine, you're still recording a signal with lower total dynamic range because the signal thru the preamp is riding closer to the preamp's noise level, reducing the total dynamic range and increasing the noise level of the eventual mix.

G.

 

[mshilarious]

Third, even if you do record the signal at lower digital levels, which in and of itself is fine, you're still recording a signal with lower total dynamic range because the signal thru the preamp is riding closer to the preamp's noise level, reducing the total dynamic range and increasing the noise level of the eventual mix.

That's almost never true.

We can conceive of a preamp as two separate internal devices (whether or not it actually has one, two, or more stages doesn't matter):

preamp noise = equivalent input noise * gain + output noise

At some point, the former figure will be much larger than the latter figure. For most designs with two stages (of course with just one stage there is only the EIN), they will be equal at around 20dB of gain, and by 40dB any subsequent stage noise will be an afterthought.

Certainly a gain limit of 55dB is not troubling from the point of view of the preamp's internal noise.