We've Got A New "King Of The Low End" LDC...

  • Thread starter Thread starter kidvybes
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PhilGood said:
It works on repeatable observations that then have to be told to the masses, who must then take on trust.;)
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Nah my friend, anyone with a converter, a DAW, a multimeter, and a 150 ohm resistor can measure EIN for herself . . . I will detail the procedure:

- Send a 1kHz sine wave out from your converter. Adjust the converter output until you measure 1VAC RMS on your multimeter.

- Loop that signal to your converter input. Note the according dBFS level.

- Adjust the sine wave to -60dBV, send to the device under test set at maximum gain. Measure its output. Calculate the resulting gain using your meter.

- Remove the test signal and connect the 150 ohm resistor. With the unit still at maximum gain, connect to your converter input.

- Using whatever analysis tool you have (there are many freebies), note the dBFS RMS level of the incoming noise signal across a 20kHz bandwidth. Subtract the measured amount of gain from the device under test, and adjust for the converter calibration you did earlier.

Note that the noise level should be well above the converter's noise due to maximum gain at the preamp, thus it should not be necessary to adjust for converter noise. Also, contrary to popular belief, amplifiers are usually quietest at maximum gain and not at lower gain settings. There is a perceptual belief that the highest gain setting suddenly adds a lot of noise, but I suspect this is actually due to rather coarse gain controls adding a large amount of gain with the final travel of the knob.

That result is unweighted EIN in dBV. If you want A-weighted, you will need to apply the weighting factors. I imagine somebody has written a freeware VST so I would look for one of those if your DAW does not have that function.

That said, the vast majority of preamps have almost pure white noise across the audible spectrum, except below 100Hz where there could be some flicker noise. In many amps, the flicker noise is confined to even lower frequencies, say 10Hz. You can see a noise density spectrum chart in many opamp datasheets, that will amply demonstrate this principle. As a result, you can be fairly confident that A-weighted will be ~3dB less than unweighted for a mic preamp that demonstrates a white noise spectrum.

This is not true for microphones, since a major source of noise for microphones is Brownian motion. Depending on the diaphragm size and sensitivity of the capsule, eventually thermal noise (white) will catch up with the 1/f noise at some frequency. That can cause a variation in the noise spectrum between two different microphones, but this is far less common in amplifiers.
 
Well thanks! But really the 2003a has, as they say in real estate, "good bones". I just applied some TLC.
 
mshilarious said:
Nah my friend, anyone with a converter, a DAW, a multimeter, and a 150 ohm resistor can measure EIN for herself . . . I will detail the procedure:
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Completely missing the point that anyone without those things, or knowledge of how to use them (which I do) has to take what you say on FAITH.

Sort of like how folks who are not cosmologists have to take Stephen Hawking on faith.

Its a lie that science doesn't require faith. For all laymen (i.e. anyone who has not tested or witnessed the results or observations of any experiment or condition personally) it DOES.
 
PhilGood said:
Its a lie that science doesn't require faith. For all laymen (i.e. anyone who has not tested or witnessed the results or observations of any experiment or condition personally) it DOES.
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Agree 100000%
 
I've been on and off this site for a few years under a cpl different names...(usually because my ex used to cancel my screen names ) I'm not an expert on mics,but I did work in a cpl studios back in the day ( 70's) and I don't ever remember anyone coming in and asking to see the specs on a mic before recording.....they usually asked for the best sounding mic for the job.......specs are great,but your ears are the final judge......I don't care if it's a $5 mic or a $5000 mic....if it sounds right for the job at hand we used it......I'm not saying don't buy the best mics you can afford,but don't be impressed by the price...I've had some really nice mics that sounded like poop,and some crappy mics that when you play it back you go..WTF.....I don't see a reason for all the fuss....if you want to buy a mic and mod it...good for you....If you want to spend the budget of some small country....good for you.....everybody has different tastes.....thats what makes things interesting......nobody should bash anybody for their choices....There are some kids down the block that have a little band......I was walking by one day and the vocals sounded great......they were using a cpl mics they put together from thrift shop parts......the cartrige was in an asprin bottle glued to a 3/4 inch dowel and wrapped in electrical tape.........lol .....pretty impressive.......anyway.......different strokes for different folks.........Can't we all just get along?............Dave
 
OK, from whom do you accept blanket statements of faith? Obviously not everyone has the same level of experience. Do you accept this formula on faith?

fc = 1 / (2 * pi * R * C)

Although that's pretty easy to verify experimentally too . . .

Because in the instant case, there are contradictory indications from users, yet none of them have actually taken a measurement. Do you disbelieve AEA's spec? Because it's pretty quiet, and not very far from the theoretical ideal:

dBV unw. = 20 * log ((4 * 1.38 * 10^-23 * 300K * 150R * 20000Hz)^.5) = -133

Which is -131dBu, or say -134dBu-A. That is the room temperature thermal noise of a 150 ohm resistor, and the AEA is a mere 4dB above that. BLA is quieter? Prove it to me. Simple test: two SM57s next to each other, spoken word, matched gain. Switch mics and repeat to control for variation in mic sensitivity.

(BLA has published no spec I can find and thus made no such claim, so I neither fault them nor believe them, since they have given me nothing to accept or disprove)

Take this on faith: in my experience in designing and building preamps, I find that most people's threshold of noise pain for use with dynamic mics is around -120dBV unweighted. Quieter than that, most people will not notice noise, louder than that, most people will. Making a couple of adjustments from V-unw. to u-A, that would mean a preamp would have to be about 9dB noisier or worse than the AEA for most users to find it to be noisy, or stated another way, AEA's spec would have to be 9dB off. Why not accept AEA on faith?

When I say "most", I presume a normal distribution. A few people are hypersensitive to noise, a few people don't care. Somebody who only ever uses dynamics on loud sources probably doesn't care that much regardless of whether they can tell that a preamp is noisy on a quiet source.
 
And that is on-point to the topic "We've got a a new 'king of the low end LDC'?
 
My initial report about the 2003A pcb was wrong - the 100uF caps are in series with the XLR pins 2&3, not shunting to ground. I corrected this in my gearsluts post but not before Marik quoted me.

So who wants to talk about the sound of the 2003A?
 
I would like to talk about the sound of the 2003A, but I have to confess I'm a little bit jealous for HR. I mean, why comments like this?

70's U 87 vs 2003A shootout coming tomorrow. But you'll have to go to Gearslutz to hear it.
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I have flat out stated that I don't really care what you post (from a moderator perspective) so long as you don't start threads to pump your own products. I'm a bit fuzzy on whether this is a modded MXL or not, mainly because I'm not really paying attention, but it doesn't matter, you didn't start this thread, so that shootout would be on topic. So post away.

That said, in my capacity as a member I'm going to discuss what I feel like discussing with respect to what is posted here. When you incorporate by reference a GS thread here, I will treat it as if your posts in that thread were made here. Therefore your comments on the AEA I treat as if they were made in this thread.

Don't feel like you get my special attention either, I'm an ass to anybody who posts along similar lines, even if they have nothing to sell. For example:

https://homerecording.com/bbs/showthread.php?t=309087

Now, when you tell me you want me to trust you with respect to shootouts, etc., then I feel that trust must be established. But you've now made three basic errors of physics in one thread:

- the preamp noise issue
- misattribution of the effect of A-weighting on measurement of preamp noise
- the 100uF thing. I mean, c'mon, sure you mistraced the circuit, but that doesn't even pass the smell test.

Have I done dumbass stuff? Of course. But I don't want anybody to trust me, I want them to question me. Trust leads to complacency, complacency leads to hunger. I like to eat, so I want to discover my errors as quickly as possible.

Now, in spite of those matters, you still apparently make pretty good sounding products. But so does AEA, so I don't think they deserve the abuse.

Anyway, that's all I have. Carry on with your mic comparisons, I don't doubt they can best some ancient German mics. And probably some modern ones too.
 
MichaelJoly said:
My initial report about the 2003A pcb was wrong - the 100uF caps are in series with the XLR pins 2&3, not shunting to ground. I corrected this in my gearsluts post but not before Marik quoted me.

So who wants to talk about the sound of the 2003A?
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Is it a Schoeps circuit?

Best, M
 
mshilarious said:
I would think not if it has output capacitors . . .
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The reason I am asking is I am completely lost--there are quite a few open ends here:

1) The original 2003 was a Schoeps circuit. I'd think, if MXL desided to re-design it, they'd give different model designation (esp. knowing they practice of doing it even for the same mic).
2) PhilGood says he does not see there any 100uF.
3) Here is the quote from already corrected Michael Joly description from that thread:

A big contributor to corrected HF sound of the 2003A are the huge R-C filters at the output which roll-off the top end.

If those capacitors are in series with output then according to physics law they rather would roll-off the low end... depending on the cap values. Indeed, there is a nice and elegant way of rolling the top in a Schoeps circuit, but nothing like described.

Something is in real odds here... just would like to understand what it is.

I'd like to see a clear picture of both sides of PCB. Anybody?

Best, M
 
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