USB microphone with low recording level

I am in the process of building a system with a remote controlled tranceiver. Therefore it is more portable with a USB-mic connected directly to the laptop. I have used Audacity to test different USB-mics to find one with low noise level. I have tested a number of cheaper USB-mics but the noise level are too high for all of them. So the frequency responce is not important but the noise level are of importance. The reason for the setting of 24 bit / 96 kHz is a lower noise level than for 16 bit / 44 kHz. I found the sE X1 USB at a good price but perhaps I have to spend more money on the mic? The Rode NT USB has good Reviews, low noise level and a mic level Control but at a 70% higher price.

OK, so their is no way to increase the mic recording level in Audacity? (I have only found the function normalize to increase the level after the recording is already done)

I am in the process of building a system with a remote controlled tranceiver.

Surveillance system? Trying to dig voices out of the mud?

You have competing requirements. I built several conference and group recording systems but I did it with a small mixer and conventional microphones. The low noise level and the ability to control volume wherever I wanted it were very valuable. They would never have worked with simple USB microphones.

Audacity can’t apply effects, filters, adjustments or corrections during recording.

A note. Most volume control systems go down. When you adjust a computer slider, you are almost always starting with natural and reducing. There were only two systems I know of that applied boost. There was a Windows “Microphone Boost” you could select in earlier versions, and this volume problem is so bad some Windows machines have a USB microphone boost. I don’t know if it’s on a switch or not. I’m not a Windows elf. Everybody else features Volume Reduction Controls any time you see a slider.


OK, so there is probably the same low recording level with the Rode mic level Control set at maximum. So perhaps the best aproach Is to look for a small interface instead and test some more analogue microphones to find a solution with low noise level.

probably the same low recording level with the Rode mic level Control set at maximum.

That’s not a hard rule, but the phrase “USB Microphone” is generally associated with your mum recording an audiobook, not someone making a difficult, unusual, or error prone recording. And all those microphone types have the same new user problem of trying to give some satisfaction without overloading.

Maybe if we knew more about the goal. There are tricks and techniques with regular microphones that can make them better for one job over another, but we need to know what the job is.

And it’s usually not the microphone making the noise. Some of the fancier condenser microphones do make a little noise on their own, but most microphones such as ribbon or dynamic make no noise. All the noise is made by the microphone preamplifier. Microphone sound level is atomic-level small and it’s up to the microphone preamplifier to boost it so it can be recorded, transmitted or combined with other microphones. That’s where the noise is.

That’s why when you buy a mixer, many of them brag about the type of preamplifier they have, and how well behaved and quiet they are.

This is from a Yamaha ad.

The MG10XU’s crystal clear D-PRE preamps will squeeze every drop of tone from your mics…

The rest of the electronics isn’t mentioned, just the preamplifiers.

There is a preamplifier inside USB adapters and a preamplfier and digitizer jammed inside USB microphones.

Oh, and they should not only make USB microphones convenient and easy to use, also make them inexpensive.

Most audio people have a chest of different microphones, cables, preamps and mixers and they change around depending on the job.

So what’s the job?


I have found these two small adapters. I suppose they have the same story?

The microphone will modulate a remote Communication transmitter (tranceiver) over the Internet. Clear voice articulation and low noise are the main goals. The microphone will also be used mobile/portable and connected to a laptop or an Ipad.

If low noise floor is your aim, stay away from these…

USB only proides 2,5 W power. That is not enough for a good mic preamp, if you also have to power a headphone amp and an AD/DA. Shure has alleviated that problem a bit by only providing 40 dB of gain. Maybe that’s enough if you use a top quality very high output condenser mic. But it’s not enough if you need to record reasonably quite sources with an average mic. I’ve never tried the Heil, but I suspect it will be equally weak.

There’s a reason why any decent audio interface has it’s own power supply. Apart from the wattage, USB power from a computer is very dirty. It requires a lot of filtering AND it also requires a voltage converter to go from 5V to 48V phantom power. That’s why some phantom powered mics simply don’t work with USB powered interfaces. Not enough juice.

If you intend to use an ipad, you have another problem. The interface needs to be USB audio class compliant. Some are, but not all. And most USB stuff dedicated to recording on ipads and iphones isn’t low noise, but depends on software running on the iOS device to filter noise. Unless you’re willing to spend a lot of money. Like the professional interfaces from Sound Devices. These are quiet, even at 100% gain.

“Standard” interfaces are more or less universal. USB mics are not. The can do one average job and fail miserably at most others, like very loud or very quiet sources.

And we still don’t know what you intend to record and how…

The microphone will be used for radio Communication and connected to a laptop. It will not be used for singing or Music. At present I am in the process of choosing a suitable microphone/interface for this purpose. I am recording different microphones in order to compare them and for future reference. The main priorities are clarity and low noise level. The voice must go through to the receiver end also during bad and weak radio conditions. (The sE X1 USB has the lowest noise level so far but not with the 16 bit / 44.1 kHz setting. With this setting there is some sort of noise in the background.)

Your worst problem is going to be operating a sensitive microphone in close proximity to a radio transmitter. That combination is usually deadly and the reason higher-end surveillance systems are shielded.

Husband/wife cheating on you?


The DIN EN 61938 standard specifies a maximum of 10 mA may be drawn by a phantom microphone. Typically the current drain for a true condenser mic is around 2 to 5 mA or less, with just a few exceptions getting close to the specification limit. Unless you are using a mic that requires exceptionally high current, or a computer with sub-standard USB, a USB powered pre-amp should be able to easily power a single microphone. The Shure X2u provides up to 50 dB of gain (not 40 dB) and 78 dB FS SNR (A-weighted) at maximum gain. The amount of gain may not be enough for low output microphones or for recording low level audio.

Regarding portability, the X2u is compact but built like a tank and could double as a bludgeon. I think koz has, or had one, so can probably give more information.

I think koz has, or had one, so can probably give more information.

I do have an X2U. I don’t think I’ve ever used it for serious recording because of low volume. All the tests were with the volume controls all the way up and it still wasn’t enough. I complained to Shure and they effectively said, “That’s the way it is.”

It’s terrific for bludgeoning, though.


And that was OK back when phantom power came from the backup lights, powered by enormous lead-acid battery banks in the basement.

Some phantom power systems these days, only provide 24V, or even 15 or 12V. And that is definitely not enough for some mics.

Don’t forget that a lot of interfaces have two mic inputs. And two times 10 mA @ 48V, is almost one Watt. That leaves only 1,5 W for the ADDA and the mic & headphone amp, providing the charge pump has a near to 100% efficiency. And most decent mic preamps don’t run on 5V, but need 12-32V, so you need a second charge pump…

Besides, if you draw more than 10 mA, the voltage will cave in because of the 6,81 kOhm resistors in each leg of the mic connection in the preamp, followed by another pair of 2k2 resistors in the mic. Totaling around 18 kOhms in series with your 48V power supply. Can you do the math, Steve?

That’s why you’ll never see a USB powered interface with preamps, phantom power and more than two channels. And a USB “dongle” like the XR2U is basically the same problem, only for one channel. With a preamp running on 5V. No headroom, lots of noise, hence low gain.

When it comes to extremely low noise mics, there’s two that spring up: the Rode NT1 and the CAD S100. Both exist in a USB version. Have you considered those?

I have a SEX. It’s a nice mic, but not the one with the lowest noise in my drawer. And I would certainly not use it for voice. Too bright.

The best USB adapter for a single mic is probably the Centrance Pro, but it’s like 200$. And for that amount, you can get better interfaces…

What about a Behringer UMC202? It’s around 40€. Or is that too big? Quality wise, it should be as low in noise as the Centrance.

And you can use it with any mic.

If you want far better, there’s always Sound Devices. But those are around 2.000$. Or RME, from 750$. Certainly a little less noise, a lot more gain. But I don’t think you need these for a voice/radio job that’s limited to what, 5 kHz? 15 kHz?

And you’ve made me curious. Why does it need to be very low-noise? Is that because it is FM radio broadcast, or is it HAM and you are doin’ some kind of processing?

I can’t imagine needing better than -60 dB noise floor for CB radio :smiley:

Does that even still exist? :laughing:

Sorry cyrano, did I hit a nerve?

No need for an apology, man!

But it is a nerve you hit. It makes me nervous that a lot of people are buying mediocre gear that isn’t even cheaper than good gear. It is smaller. But that is usually not very important.

And sorry if it came across as a rant. I sometimes do rants :blush:

I get nervous about false statement like: “USB only proides 2,5 W power. That is not enough for a good mic preamp”.
If you’ve seen a review of the X2u that says that it does not provide adequate phantom power, it would be more useful to give a link than make an unsupported sweeping statement.

It’s an explanation of the problem in general. And I’ve come across the problem enough times myself to know what I’m talking about…

I own several mics that don’t perform to well with most USB powered interfaces, for reasons stated. A lot of AKG mics are known for pulling enough current to be a pita with a USB powered interface, especially as they get older and caps start leaking a bit more. Yet, all of these work with classic mixers, preamps and interfaces that aren’t USB powered. And most computers will even supply more than 500 mA. An old Apple Cube G4, fi, can supply 2,2 A on both of it’s USB ports. But my MB Pro craps out at almost 600 mA. When you go to tablets, some can’t even provide 500 mA.

OK, but your post read like it was specifically addressing Remote’s question, in which he specified two products: Shure x2U and Heil Sound USBQ.

Taking the first of these as an example, the Shure x2U specifications state:
Phantom Power Supply 48 V, 10 mA
Power Requirements USB-powered, 500 mA, maximum

You mention AKG mics as being known to pull a lot of power, so let’s take one of the most power hungry AKG studio mics as an example, the C414 XLII. AKG’s specification state:
Powering Interface:
Voltage 44 to 52 V
Current 4.5 mA

Do you see how your statement that “USB only proides 2,5 W power. That is not enough for a good mic preamp” might give an inexperienced user a false impression about the ability of a Shure x2U to provide adequate phantom power? I’m sure that you agree that we need take care not to mislead inexperienced users that are asking for guidance.

It’s fair comment that a full 500 mA may not be available from all USB sockets. The USB specification (prior to USB 3) states “5 units” at 100 mA per unit, but it’s not uncommon for budget laptops to share USB ports between multiple USB sockets (in effect, a passive USB hub inside the computer) for the sake or reduced cost.

What are the real world symptoms of a power mismatch?

I know of no modern system less than 48 volts. The other voltages are from way back when there were no common power management chips. That was sorted and suddenly, all those oddball values, 5v 12v, etc. etc, vanished. Many microphones are clear they won’t work right with the lower values.

Some will work from floor sweepings. You have to pay attention.

There was one preamp device I busted a long time ago which claimed in Very Large, Bold, Helvetica Type that it had Phantom Power!!!

Only if you dredged down to the bottom of the last page of the manual that they admitted, in very small type, that it was the older 12 volts.



The symptoms are not always the same. The AKG C451 works, or doesn’t work mostly. But on my Sound Devices USB Pre, it would “motorboat” if you know that sound from a runaway amp. The Behringer takes one to two minutes to stabilize. Until thap happens, it seems to work, but it immediately craps out with a lot of hiss on loud sounds. And I have an NT1 (one of the very first) that stutters, a C414 that whistles (the mic membrane, not the output), so I’m careful not to use that one on unknown interfaces. I fear it might damage the capsule.

All of these work fine on a mixer, or an interface with its own power supply. But they show different behaviour on various USB powered interfaces.

48V was chosen by accident by the Scandinavian radio station that pioneered phantom power, because their emergency lighting ran on 48V. Coming from large battery banks, it was clean and plenty. The standard came around some 20 years later.

24V was also added much later. Because of cheapness and the fact that the large majority of condenser mics is fine with it. 15 or 18V phantom shouldn’t exist. The only reason you’ll see 18V is because two 9V blocks in series can provide it. 15 is a crime. I estimate that around half of the condenser mics on the market are not fine with it, showing limited headroom, and/or a higher noise floor, if they work at all.

12V was T-power. Entirely different beast, much older. Mostly Sennheiser. Abandoned today, not balanced. Less CMIR. And if you plug in a T12 powered mic into 48V phantom power, something will likely blow. Adapters exist. You’ll find it in the first and second generation MKH mics from Sennheiser, so you’ll find it on older Hollywood gear. The only mixer I have that sports 12V T-power, is a Sennheiser MK101, an old broadcast portable 4 channel mono mixer. It has 80 dB gain from input to output, but you can also use it as a line-input, because gain starts with a tapped transformer.

1,5 to 10V is usually pip (power in plug, I think) power. Only for electret mics on portable recorders, PC’s, video camera’s. Yet another topology, not suited for “real” condensers, e.g. condensers that need high polarisation voltage.

I’m pretty sure not many would confuse the 1/8" soundcard socket microphones with anything on an XLR. I know quite a few people that would like to confuse them. I did make two adapters so I could plug my unbalanced lavaliers into my XLR mixer. The lavaliers have local battery, so I never ran into the power cross problems.

The Shure FP-33 field mixer will switch between 12 old style and 48 with little switches on the motherboard. Amaze your friends.

This mixer model is hard to kill. I believe this is the one that went on a sound shoot inside a speeding cigarette boat in Florida’s Biscayne Bay (I have the button layout stuck to the bottom). That wasn’t me. Wrong coast. I believe the shotgun microphone was never reliable after that.

It satisfies the old joke of being a successful product. Most of the paint is gone and you can’t read the knobs and dials any more. You can’t see it right now because it’s out on a job.


Hey Remote,
I have exactly the same microphone. It’s not the expected behaviour that the microphone is recording at such a low level. If you connect your headphone to the monitor jack you realize the microphone itself is able to record the birds from the next street. The microphone uses a board from XMOS ( and the XMOS USB Audio 2.0 Stereo Driver version 3.34.0 is the latest driver you can get from sE Electronics. The driver is developed by Thesycon ( and the product is called “TUSBAudio” (Thesycon USB Audio). They state the driver is compatible with Windows 10 and yes, it works but even if you drag the level slider to 100% it’s still too quiet. There is no boost functionality available.

I just recorded directly in front of my speakers where I played a song at normal loudness (something you can hear :stuck_out_tongue:); have a look at the attachment. When I amplify that so I can hear something it sounds horrible. With voice it’s not too bad because, well, my voice is horrible anyway, but this is clearly not ok.

The SE-X1 USB is now a legacy product. My advise is to create a support ticket at

I have several other USB microphones and none have this problem. My first USB microphone was the Auna MIC-900B which I still have as of today. If I turn the level slider to 100% I can record the birds from outside. I always set the slider to 90% or even lower with that one.

So please open a support ticket at sE Electronics. Your microphone is broken and not working as expected. ← have a look; he’s not “eating” the microphone and still getting decent loudness. If you follow the video you can even see that he’s setting the level to 60% :slight_smile:. And he can even record his guitar with it. This is clearly not possible with my SE-X1 USB. The best you can hope is they are replacing it with the SE-X1 (the one with the xlr connection). I followed the SE-X1 and SE-X1 USB for some time. When the USB variant was released, it was more expensive than the one with the XLR connection. That quickly changed and the XLR variant was more expensive than the USB one. The USB one quickly dropped to 100 USD (sE Electronics nearly asked 300 USD when they released it).

I suspect it’s a driver problem. The russian guy in this youtube video uses Windows 7. For me this was my last USB microphone :slight_smile:.