Shure SM7B/MVX2U XLR-to-USB

[posttokev]

Hi all. Wondering if anyone can offer any guidance regarding the Shure SM7B mic and Shure MVX2U XLR-to-USB adaptor.

The mic's sound quality is a bit "harsh" (for want of a better description) and, as it's gain hungry, there's hiss present in recordings. It doesn't have the smooth and hiss-free sound I hear from other users of this mic in their YouTube videos. I can address in post-production but am hoping there is a way to do so up front, and reduce the amount of post-prod necessary.

I flag up that I use a Shure MVX2U XLR-to-USB in case that might contribute to these issues in any way? Also, I note that when I listen to the mic via the MVX2U's headphones jack, the hiss is far greater live than in the resultant recorded audio. Does anyone have any idea as to why that would be?

Any thoughts regarding workarounds would be much appreciated.

[ef37a]

Assuming you are using a Windows PC you might have the gain set too high in the Windows Sound Settings menu? The Shure seems to be a "generic usb audio device" and so will be run with Windows drivers? The specc' says it has a "-117dBFS noise floor"? Pretty good that!

That might also account for the level difference twixt headphone and recorded levels.

Dave

[Wonks]

The spec sheet isn't clear about how you achieve it, but it says 16/24 bit conversion. The default may be 16 bit for easy USB connection but you want 24 bit for the lowest noise floor. Have a look in the associated app for somewhere you can set up the word length to 24 bit (if not already).

[ef37a]

You need a Cloudlifter or similar. I use a Klark Teknik C1 with my SM7B.

Do you mean in addition to the Shure converter? Their noise specc' would suggest it is suitable for the SM7b and indeed suggest so.
And Wonks, for sure OP needs 24 bits. Not going to get close to -117dBFS with 16! But I am convinced this is a gain staging problem...could be a borked unit of course.

Dave.

[Bob Bickerton]

I happen to have a Shure X2u and an SM7B, not that I've used the X2u in an age.

So the Shure SM7B is not the most sensitive of mics, but with the Mic Gain on the X2u on max it delivers a clean sound when just whispered into the mic and no audible hiss when the X2us volume control is on max and the monitor control is in mid position.

I was quite surprised at how well it performed!

This is on a Mac, but it works just as well on an independent USB power supply, so unless your computer is providing dirty power?

The SM7B is a mic that needs to be worked close for best results, like a stage mic.

Bob

[James Perrett]

The specc' says it has a "-117dBFS noise floor"? Pretty good that!

It depends where you look. The manual says -105dBFS. The specs are really very sketchy as there's no mention of EIN which is the parameter that is really needed here.

[ef37a]

The specc' says it has a "-117dBFS noise floor"? Pretty good that!

It depends where you look. The manual says -105dBFS. The specs are really very sketchy as there's no mention of EIN which is the parameter that is really needed here.

Indeed, but -105dBFS is still better than 16 bits can achieve. Have had a few 16 bit devices, USB mics, USB mixers and once Windows gain was optimised they delivered a very decent noise performance.

Dave.

[Wonks]

I happen to have a Shure X2u and an SM7B, not that I've used the X2u in an age.

The X2U and MVX2U are fairly different beasts. The (now discontinued) X2U had manual controls for gain and volume whilst the MVX2U seems to rely on its app for gain and volume settings etc. So it definitely will require some tweaking in the app to get the best performance from it.

The X2U was 16-bit only and offered 50dB of gain. The MVX2U has 24-bit capability and 60dB of gain, so should be able to get even better results. But it does need to be set up correctly to get those results.

[Bob Bickerton]

My mistake, sorry, but potentially good outcome for the op.

Bob

[Wonks]

Provided the app allows control, and the 'smart gain' function in the MVX2U actually does what it's supposed to. Hopefully there's a manual gain setting mode as well.

But as the MVX2U can provide phantom power, a Fethead or Cloudlifter between the SM7B and the MV2XU might be worthwhile if the mic is being used in a more distant position and not right next to the mouth (though a condenser mic will be more appropriate (if less 'hip') for that situation.

But if you do try a signal booster, I'd use an XLR/XLR lead to connect between the mic and the booster/MVX2U combination as two rigid connection devices in series poking out of the back of the mic is just asking for trouble. A lot of leverage on the mic connection if it gets caught or the cable pulled.

[ef37a]

"But if you do try a signal booster, I'd use an XLR/XLR lead to connect between the mic and the booster/MVX2U combination as two rigid connection devices in series poking out of the back of the mic is just asking for trouble. A lot of leverage on the mic connection if it gets caught or the cable pulled."

Good point Mr W and in fact since the absolute max length for USB 2.0 is 5m and 3m safer, it is probably advisable to have the MVX2U (+ lifter maybe) on quite a short USB cable close to the PC? Also, USB connectors are a lot more feeble than XLRs!

Dave.

[ajay_m]

You can go a lot longer on USB with an active cable - 20m cables are available for instance. There's a little chip on each end to act like a repeater does on a communications cable, so don't let cable length dictate your setup.

[ef37a]

You can go a lot longer on USB with an active cable - 20m cables are available for instance. There's a little chip on each end to act like a repeater does on a communications cable, so don't let cable length dictate your setup.

Yes but in this application I don't see the point? Keep the fragile bit close handy and extend the XLR cable as long as you like...JUST 20m? Having a giraffe!

Tell you all what ARE fragile? HDMI plugs, managed to knacker two in the last month and I am not generally a clumsy person.

Dave.

[posttokev]

Hi all,

Thanks very much for so many considered responses to this. I'll address your points in turn:

ef73a: If I go below anything in the high 90s in Windows sound settings > microphone > input volume, the mic output is pretty much inaudible. (Is this what you mean by gain in Windows sound settings?)

Wonks: I don't record using its app Motiv Mix, but into Adobe Audition. This has always been 16 bit. I have recorded at 24 bit but cannot discern any difference as regards my issues with audio quality. I'll continue to record at 24 bit though.

Bob Bickerton: I don't have an independent power supply. The mic is powered solely by my Windows laptop. Might this be the cause of the audio quality issues?

Wonks: The mic is used to record a podcast voiceover and I am always quite close to it. However, if I get too close, there is distortion. (I am a former radio presenter and could get similarly close to mics in radio studios without such distortion.)

Thanks again for your guidance, which is very much appreciated.

[ef37a]

"ef73a: If I go below anything in the high 90s in Windows sound settings > microphone > input volume, the mic output is pretty much inaudible. (Is this what you mean by gain in Windows sound settings?)"

That is odd. I don't have your rig of course so I have done a series of recording at various Windows gain levels with a USB mic, Citronic CCU3. The settings ranged from 60% down to 6% and each "rain in Spain" went down smoothly in level as averaging -20, -25, -30 and -40dBFS. All very approximate of course. Naturally, had I spoken louder, or got closer than the ~100mm I was at, the level could have been restored.

The fact that your setup does not seem to behave that way AND the distortion you mention leads me to think the Shure converter is faulty.

Dave.

[Drew Stephenson]

I think we might need to go back to basics. Can you borrow another mic and cable to check independently that they're both working correctly. Then see if you can find someone with an audio interface to check with as well.
It does sound like there's a problem in the chain somewhere but we don't know where.

[posttokev]

"ef73a: If I go below anything in the high 90s in Windows sound settings > microphone > input volume, the mic output is pretty much inaudible. (Is this what you mean by gain in Windows sound settings?)"

That is odd. I don't have your rig of course so I have done a series of recording at various Windows gain levels with a USB mic, Citronic CCU3. The settings ranged from 60% down to 6% and each "rain in Spain" went down smoothly in level as averaging -20, -25, -30 and -40dBFS. All very approximate of course. Naturally, had I spoken louder, or got closer than the ~100mm I was at, the level could have been restored.

The fact that your setup does not seem to behave that way AND the distortion you mention leads me to think the Shure converter is faulty.

Dave.

Just to clarify, when you reference Windows gain levels, do you mean the mic's input level in Windows sound settings?

A bit more detail on what I touched on previously - if I adjust the input sequentially down from 100 (hissy/bit harsh), the audio volume seems to roughly halve.

So, 99 is half as loud, 98 half as loud again and so on. (95 is barely audible.) The hiss is still evident if I boost the quieter audio.

[Bob Bickerton]

Not a windows user, but if the Shure system is used as an audio interface, why is the Windows mic level coming into play? The Shure is selected as the audio input source yes?

Bob

[ef37a]

Not a windows user, but if the Shure system is used as an audio interface, why is the Windows mic level coming into play? The Shure is selected as the audio input source yes?

Bob

I can only give my ideas here Bob. Most USB audio devices like that Shure and USB mics are "generic audio devices" that is they work straight away from a Windows driver. Thus they are under the Windows sound control menu.
"Proper" USB audio interfaces use ASIO drivers which keep Windows sticky mitts off your gear.

I am still of the opinion that the chap has a faulty device. I have had sheds of cheap USB dongley things over the years and they all returned about a 85dBFS noise floor (all were only 16 bits) I include in that list the Behringer UCA202 a handy little box for £20 or so but capable of a better dynamic range than any Dolby B cassette machine.

Dave.

[ef37a]

I have just recorded the baseline noise of the SARBRENT USB device. Two 3,5mm jacks, mic in, headphones out. It seemed to set itself to 50% in the Windows menu. That returned a noise floor in Samplitude of -75dBFS. Not a bad result for a ~10 quid device? I certainly don't recall any noise problems with it on a headset, sadly now defunct so I cannot try an input.

I did the same thing with my M4. Mic gains fully down and for 24 bits -100dBFS which I take to be mostly mic pre* noise? ASIO drivers of course.

*XLRs open circuit. I have a screened 150R termination somewhere. Will have a shufty for it and see if it makes a difference.

Dave.

[ef37a]

it didn't.

Dave.

[posttokev]

Currently enquiring with Shure about these issues as well. They say:

"this shows us that you might need more gain. You can get a TritonAudio Fethead or Cloud CL1 which give you more clean gain. i don´t think there is anything wrong with the Shure products - maybe not enough gain for your voice. Therefore, try the recommended solutions and see, if they work."

Are they saying the Fethead/CL1 are better quality preamps than the MVX2U? Also, I have used the SM7B with other voices but encounter the same issues.

[Drew Stephenson]

I think you need to beg, steal or borrow some access to alternatives so that you can check each link in the chain (mic, cable, interface). Otherwise we're grasping at straws here. Whereabouts in the world are you? There may be someone close by who can help out.

[ef37a]

Currently enquiring with Shure about these issues as well. They say:

"this shows us that you might need more gain. You can get a TritonAudio Fethead or Cloud CL1 which give you more clean gain. i don´t think there is anything wrong with the Shure products - maybe not enough gain for your voice. Therefore, try the recommended solutions and see, if they work."

Are they saying the Fethead/CL1 are better quality preamps than the MVX2U? Also, I have used the SM7B with other voices but encounter the same issues.

I would certainly expect the Fethead and similar devices to have a better noise performance than the MVX2U, just in the nature of things but since they do suggest it works with a 7b it really should unless you have an unusually quiet voice or are a long way off the mic? But then that does not explain the distortion? Got to be a duff unit IMHO.

Is this a laptop? If so, what sort of results do you get with the built in mic?

Dave.

[Wonks]

Are they saying the Fethead/CL1 are better quality preamps than the MVX2U? Also, I have used the SM7B with other voices but encounter the same issues.

No. Using a Fethead or a Cloudlifter is very common with an SM7b, due to its low output. They are low-noise in-line signal boosters, typically with around 20dB of gain. They don't replace your preamp or MXV2U, but they boost the signal going in to it, so you don't have to run your preamp at maximum gain (where most preamps start to get noisy). They need phantom power to work, which is passed on from the MX2VU.

However, I'd question why Shure pair the SM7b and the MXV2U if they don't expect reasonable results from the set. In the SM7b manual it does state:

"The SM7B has a sensitivity rating at -59 dB and requires more gain than what most entry-level or mid-tier preamplifiers can deliver. Use an inline boost amplifier or stronger preamp if your preamp does not have more than 60 dB of gain".

As the MXV2U has 60dB (and not more), then it would seem that it's not a great pairing with the mic and Shure should really have provided such a booster as part of the package.

However it could still be that it's a faulty unit or mic.

Are you able to try the mic into someone else's audio interface or into a mixer to check the mic is operating correctly?