Background noise reports - mic / gain setup?

[VK3ICM]

I've been getting reports of 'background' noise in QSOs for a long while. My operating position used to be in a room with nearly all hard surfaces so I attributed it to that, but have now moved to a different spot which should be better and it persists, so I think something in my setup must be off.

Setup:

7000DLE mk2 using VAC. I have a Samson CL7a mic that goes into a Motu M2 audio interface and I'm using the Asio drivers in Thetis 2.9.0.8.

I've been through W1AEX CFC tools setup numerous times. In order to hit close to 0dB on the Thetis TX MIC meter and LEVELER (for reliable PS operation?), I have Setup > Audio > Gain (dB) TX = 7, my TX EQ preamp just below mid scale, and the Motu gain for the mic pretty close to max.

With headphones plugged into the Motu M2, with drive to 0, if I hit TX and use MON, I can hear the MIC is picking up every minute sound through the house. The MIC meter reports an ambient level of around ~-50dB.

Does this behavior seem way off? I'm using a basic desk stand for the mic, so I'm probably typically a foot away from it when TXing. I also wonder if it is preferable to add gain at the Motu audio interface vs. in Thetis or vise versa. Appreciate any thoughts!

[K4IBC]

I would try reducing the Motu gain first. Try being closer to -3 in the whole audio chain rather than 0. Also with the Motu maxed you are overdriving the interface. You didn't mention what microphone you are using.

[w-u-2-o]

I'm using a Behringer B1 large diameter condenser into a Presonus Studio 192 interface. It is twice as sensitive as the CL7a, 20mv/Pa vs 10mv/Pa, and I don't have any objectionable room noise.

Your gain settings seem insanely high across the board. The Motu gain should not be anywhere close to max. I'm only using 50% gain on the Presonus with the B1.

First order of business: unless you are in a very quiet, dead room (aka recording booth) you cannot use your condenser "studio style", i.e. sit back a foot or two from it. You've got to be right on top of it, within an inch or three.

Second: mic gain should be set by the first gain stage and every stage after that should be set to 0dB until you get to processing stages (the first would be the leveler). Put your VAC TX gain at 0dB. Or if you are using cmASIO, put the MIC gain at 0dB with mic boost OFF. Then adjust the Motu gain until you see around -3dB peaks on the Thetis mic meter.

Dumb question: you do have 48V phantom enabled for this mic on the Motu, right?

Finally, there is nothing wrong with a -50dB background in a live room. That's what my background level is (mostly computer fan noise). If you run the mic close (inches), have gain set appropriately, and use the downward expander (aka noise gate) appropriately, then any background noise should be all but unnoticeable.

[VK3ICM]

Thanks Scott - yes phantom power is on. Clearly a boom arm is now on my shopping list.

If I shoot for ~ -3dB peaks on the MIC meter via the gain on the Motu (VAC TX gain at 0dB, TX eq off), I do see some minor clipping on the Motu display on the pops and whistles. Maybe thats ok?

[K1LSB]

Thanks Scott - yes phantom power is on. Clearly a boom arm is now on my shopping list.

If I shoot for ~ -3dB peaks on the MIC meter via the gain on the Motu (VAC TX gain at 0dB, TX eq off), I do see some minor clipping on the Motu display on the pops and whistles. Maybe thats ok?

I'm not Scott but I have an Motu M4 and I can attest that anytime I see a red square appear at the top of the Motu meter then there is clipping going on, which is NOT desirable. Properly set up, you should be able to drive sufficient mic audio level into Thetis to trigger PS Feedback without the Motu meter ever going into clipping.

Mark

[VK3ICM]

Properly set up, you should be able to drive sufficient mic audio level into Thetis to trigger PS Feedback without the Motu meter ever going into clipping.

Thanks Mark - out of interest what mic are you running? I think I'm in a much better place now - most of my trouble appears to have been my poor mic placement.

[K1LSB]

Thanks Mark - out of interest what mic are you running? I think I'm in a much better place now - most of my trouble appears to have been my poor mic placement.

Audio-Technica AT2035.

Mark

[w-u-2-o]

Thanks Scott - yes phantom power is on. Clearly a boom arm is now on my shopping list.

If I shoot for ~ -3dB peaks on the MIC meter via the gain on the Motu (VAC TX gain at 0dB, TX eq off), I do see some minor clipping on the Motu display on the pops and whistles. Maybe thats ok?

I'm not Scott but I have an Motu M4 and I can attest that anytime I see a red square appear at the top of the Motu meter then there is clipping going on, which is NOT desirable. Properly set up, you should be able to drive sufficient mic audio level into Thetis to trigger PS Feedback without the Motu meter ever going into clipping.

Mark

As Mark says, clipping at any point in the chain is not desirable. This is not to say the occasional clipping is anything to worry about, but you certainly don't want it to happen very often.

Now that you are closer to the mic, some sort of foam cover or windscreen type pop filter is pretty much mandatory with any large diameter condenser microphone. If you don't already have one then getting one will substantially reduce clicks/pops/breath sounds and will allow you to keep the Motu gain higher. That said, it seems like you've got things better under control now. If you want to drop the Motu gain a little and add 2 or 3 dB of VAC TX gain that will be fine, but with the right windscreen that should not be necessary.

You don't need boom arm per se, although they do look cool. I just use a desktop mic stand. Either way, you definitely do want a shock isolator to put between the mic and boom or stand.

You are really going to start enjoying your audio now that you've got the big things sorted out.