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sure sm78 levels seem low

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sure sm78 levels seem low

Postby thisismyusername » Fri Feb 28, 2020 12:33 pm

Hello everyone.
I recently replaced a AKG 3000 with a new SM78 in a radio station. However there is a massive drop in the levels. When I present with the AKG my level is set at -13, with the Sure it is +11. Obviously I can adjust the gain but that brings up too much background hiss.
I have adjusted the responses on the sure but with no effect.
Am I missing something.
Thanks
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Re: sure sm78 levels seem low

Postby Tim Gillett » Fri Feb 28, 2020 12:49 pm

Assuming you mean an SM7B, yes the level will drop greatly.

Probably nothing wrong with the SM7B. It's just a low output mic re the 3000.
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Re: sure sm78 levels seem low

Postby Hugh Robjohns » Fri Feb 28, 2020 12:53 pm

thisismyusername wrote:Hello everyone.
I recently replaced a AKG 3000 with a new SM78 in a radio station.

There is no Shure SM78... I presume you mean a Shure SM7B (B as in Bravo)?

However there is a massive drop in the levels.

Yes, of course there is!

The C3000 is a reasonably high-output capacitor mic with a specified sensitivity of 20mV/Pa. In contrast, the SM7B is a low-output dynamic mic with a specified sensitivity of 1.12mV/Pa.

That makes the SM7B about 25dB quieter than the C3000.

When I present with the AKG my level is set at -13, with the Sure it is +11.

Sounds entirely plausible! If those gain control marks are in decibels, 13+11 is 24dB which corresponds almost exactly to the different mic sensitivities. :-)

Obviously I can adjust the gain but that brings up too much background hiss.

You'll either need a better, quieter mic preamp, or an in-line gain-booster. The latter is probably the easiest solution -- something like the Cloud Microphones Cloudlifter, or the FEL Mic booster, or the Royer dBooster... there are many other similar devices around. They all require phantom power to operate, but most don't pass phantom to the output as they are intended for use with ribbon mics or dynamic mics like the SM7B etc.

You would simply need to plug the gain booster between the mic and the preamp input (so you'll need another short XLR cable), and make sure phantom power is turned on. The in-line booster will raise the output of the SM7B by about 22-25dB so it will end up at more or less the same level as you had before with the C3000, but hopefully without the preamp noise.

Am I missing something.

Yep... an appreciation of microphone specifications! :D
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Re: sure sm78 levels seem low

Postby CS70 » Fri Feb 28, 2020 12:54 pm

A cloudlifter is the usual solution.
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Re: sure sm78 levels seem low

Postby jimjazzdad » Fri Feb 28, 2020 1:57 pm

A Fethead inline booster would work well too...might be the cheaper solution in Europe (not sure where the OP is).
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Re: sure sm78 levels seem low

Postby Zukan » Fri Feb 28, 2020 2:01 pm

Cloudlifter dude. That's what I use for the SM7B here at my studio.
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Re: sure sm78 levels seem low

Postby Hugh Robjohns » Fri Feb 28, 2020 2:04 pm

The OP has contrived to stay as anonymous as possible and not given any location details in his registration... but I have reason to believe he's probably at a college radio station in Scotland.

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