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Lectrosonics and G3 Noise Floor - What Am I Doing Wrong?


Paul F
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I'm interested in buying one of the big 3 (Lectro, Wisy, Zax) wireless. But before I drop 10k, I thought I'd see what I was getting in the way of noise floor. I can't find any examples comparing the two. I rented a 411a/LMa to compare to the G3. To my surprise, the Lectrosonics noise was louder.  I figure my setup is wrong. Please have a look and comment.

 

Lectrosonics:

COS-11D plugged into an LMa.

LMa gain set to a level so that the Zoom F8 is reading -12db for the peaks

411a plugged into Zoom F8

411a gain set to 0

Zoom F8 gain set to 28db

 

Sennheiser:

COS-11D plugged into SK100

Sensitivity set to -18db so that the Zoom F8 is reading -12db for the peaks

PK 100 plugged into Zoom F8

PK 100 gain set to 0

Zoom F8 gain set to 28db

 

 

 

 

 

 

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I have lots of Lectro and lots of the cheap Sennys, from 3 generations of that model.  I never thought my Lectros were quieter than the Sennys, but I do think they sound better, both in general and certainly when you "stress" them.  By this I mean certain kinds of sounds (equivalent to the old "keys test") or sudden shouts etc.  I also felt like the range tended to be a bit better and more solid within that range.  That's what you are paying for.....  Thus the Sennys work pretty darn well for cam hops, with a line level signal that has had its dynamic range managed, but less well as the "primary" mic pre.  I do post on lots of indie content docs, on which the Sennys are very much the wireless of choice, and I hear how they fall apart under stress all the time....   But for normal level talking, they are usually fine, ok.

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4 hours ago, Paul F said:

I'm interested in buying one of the big 3 (Lectro, Wisy, Zax) wireless. But before I drop 10k, I thought I'd see what I was getting in the way of noise floor. I can't find any examples comparing the two. I rented a 411a/LMa to compare to the G3. To my surprise, the Lectrosonics noise was louder.  I figure my setup is wrong. Please have a look and comment.

 

Lectrosonics:

COS-11D plugged into an LMa.

LMa gain set to a level so that the Zoom F8 is reading -12db for the peaks

411a plugged into Zoom F8

411a gain set to 0

Zoom F8 gain set to 28db

 

First, turn off the F8 so it won't distract you!!!

 

Set the gain on the LMa according to the manual:

3) Prepare the signal source. Position a microphone the way it will be used in actual operation and have the user speak or sing at the loudest level that occur during use, or set the output level of the instrument or audio device to the maximum level that will be used.

4) Use the and arrow buttons to adjust the gain until the –10 dB glows green and the –20 dB LED starts to flicker red during the loudest peaks in the audio.

 

Set the output on the 411 to max. It won't overload.

Now turn on the F8 and set the gain for your desired output level.

 

Setting the transmitter gain should be independent of any other setting for gain or level in your system. Set the transmitter first and then raise or lower the mixer or recorder gain for your desired levels, leaving the transmitter alone.

Best Regards,

Larry Fisher 

 

 

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As always, thanks for the help Larry. While that did change the settings on the F8 (G3@33db, Lectro@10db), the noise level on the Lectrosonics is still significantly louder than the G3.

 

That is surprising. While nice, I don't need the features that these upper tier systems provide. The one thing I wanted was a better noise floor. I had a system in the Trew cart a couple of times, but I just couldn't hit the buy button without listening to at least one of these systems. Now I don't know what to do.

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I can attest to how horrible a mic with the wrong wiring can sound.  When Lectro first implemented servo bias Tx's, not a lot of us knew about the difference in wiring required for the mic's.  I actually sent back an entire SRb system and had it swapped out for a brand new one, only to have it sound just as bad.  Then my dealer, obviously not wanting to swap out another system, contacted Lectro and found out the lav's needed to be wired differently.  Problem solved.

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2 hours ago, LarryF said:

Hi Paul,

For further trouble shooting, what is the actual wiring of the mic?

Best Regards,

Larry Fisher

Larry, it was wired per the diagram labeled "COS-11 normal" at this link - https://sanken-mic.com/en/qanda/index.cfm/11.20

It was a rental package, so I assume they have it right, but I checked anyway.

 

[edit] The above is wrong - it was wired per "COS-11 red mark" and it does have a red band on the cable. There was no resistor inside the connector.

 

 

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47 minutes ago, Paul F said:

Larry, it was wired per the diagram labeled "COS-11 normal" at this link - https://sanken-mic.com/en/qanda/index.cfm/11.20

It was a rental package, so I assume they have it right, but I checked anyway.

 

[edit] The above is wrong - it was wired per "COS-11 red mark" and it does have a red band on the cable. There was no resistor inside the connector.

 

 

My COS-11's that are wired for servo bias have gold serial number bands.  I also have two "universal" wired 11's and they have silver serial number bands.

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I am experiencing almost this exact same issue. I have borrowed two sets of 411a/UM400a with COS11-D's for a shoot and have them going into a Zoom F8. I am positive I have the gain staging set properly. When I compare side by side with my Sennheiser G4 and MKE2 mic, the Sennheiser noise floor is MUCH quieter. I have tried coming into the F8 at both mic and line level (while adjusting 411a output) and there is no difference. I have also swapped the COS11-D's and that did not make any difference either. I do not have extensive experience with Lectrosonics, but have read the manuals front to back trying to get to the bottom of this. The noise floor on the Lectros is quite distracting and I have a hard time believing that such a well respected product is supposed to sound like this. I will take a look at the mic wiring tomorrow.

 

To be sure: a COS11-D going into a UM400a should be wired either SERVO or universal, correct?

 

 

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@Paul F and @Teom: any chance you can borrow or rent another recorder? You both are using F8s and having an issue, so I'd eliminate the Zoom as the problem. I'm not blaming the F8 (I use an F8n) but sometimes gear just doesn't play nicely together. When I worked in sound reinforcement we had an issue where Cadac mixing consoles refused to work with Earthworks mics; the mic was fine on another mixer and the Cadac input was fine with any other mic, but the combo just didn't work.

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Not for me. The Lectrosonics is going back to the rental house today. It was a surprising and disappointing experience. It has left me confused. I think the best next step is to get together with someone that has a working system and listen to it.  I'd really like to hear a Wisycom MCR54 system.  Is there anybody in the San Francisco Bay area that would be willing to get together that has an MCR54?

 

Regarding playing nice together, both the F8 and the 788T have the same input impedance, so I don't see that there would be an interface issue.  The 411a output is balanced while the G3 output is unbalanced going into a balanced input so if anything, the 411a  should play nicer.

 

 

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This is probably unrelated but I remember when the 664 first came out, I tried plugging G3 receivers into the mic inputs. I think when they were turned off, there would be just a crazy amount of white noise. Sound Devices went and did free upgrades on the inputs to deal with what I believe was an unbalanced connection coming in. I guess what I'm saying is, maybe it also has something to do with the Zoom's inputs.

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16 hours ago, Paul F said:

 

[edit] The above is wrong - it was wired per "COS-11 red mark" and it does have a red band on the cable. There was no resistor inside the connector

From what I've experienced, a red dot lav will appear to add significantly more noise than a regular lav (10db?) I would guess that is why it sounds like the system had more noise.

 

A red dot lav is for situations where you have a very loud sound source.

 

My expectation would be that if you used a standard cos-11, you would be impressed. I've never noticed more noise floor on any of my Lectro systems VS a G2/3

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I read up on the red dot COS-11D. From Lectrosonics back in 2012:

 

"We recommend wiring the standard level COS-11 in a 2 wire configuration with a 1k resistor in series with the white wire (source wire) to ground. This reduces the output of the standard mic by 6 dB which will prevent overload of the input buffer on the UM400. This isn't necessary for the SM series since it cannot be overloaded by the COS-11 under any circumstances. It does make the microphone compatible with both transmitter series."*

 

From a member of JW back in 2012, "When I purchased two of the red dot COS-11's a few years ago, it was at the advice of my sales contact at LSC -- I had also purchased two Lectro MM400c's, and it was explained to me that with this particular TX, the RF gain was somehow tied to the main output level of the unit -- thus a higher gain setting on the TX delivered better RF performance... the 10dB pad built into the red dot COS-11 was essentially meant to compensate for the higher gain setting on this TX."

 

I don't know how any of this applies to the LMa I was provided, but it's clear that the red dot was provided to improve performance of some Lectrosonics transmitters, not to be used in loud situations. So for all I know, I was provided the correct microphone. 

 

*The wiring diagrams at this link show the resistor to be used for the normal wiring, not the red dot wiring, which is backwards from the notes above. I'm confused. https://sanken-mic.com/en/qanda/index.cfm/11.20

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All things being equal - if you're using a red mark cos-11 (-9db) and have the 411 at 0 (-5db) then you're adding 14db of noise to your signal.

 

Correcting the gain structure will still result in 9db extra noise because of the red mark lav, unless you need the red mark lav to prevent overloading of the transmitter, which is unlikely with a typical speaking voice.

 

You could always ask the rental house if they provided a red mark on purpose.

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3 hours ago, Paul F said:

I read up on the red dot COS-11D. From Lectrosonics back in 2012:

 

"We recommend wiring the standard level COS-11 in a 2 wire configuration with a 1k resistor in series with the white wire (source wire) to ground. This reduces the output of the standard mic by 6 dB which will prevent overload of the input buffer on the UM400. This isn't necessary for the SM series since it cannot be overloaded by the COS-11 under any circumstances. It does make the microphone compatible with both transmitter series."*

 

From a member of JW back in 2012, "When I purchased two of the red dot COS-11's a few years ago, it was at the advice of my sales contact at LSC -- I had also purchased two Lectro MM400c's, and it was explained to me that with this particular TX, the RF gain was somehow tied to the main output level of the unit -- thus a higher gain setting on the TX delivered better RF performance... the 10dB pad built into the red dot COS-11 was essentially meant to compensate for the higher gain setting on this TX."

 

I don't know how any of this applies to the LMa I was provided, but it's clear that the red dot was provided to improve performance of some Lectrosonics transmitters, not to be used in loud situations. So for all I know, I was provided the correct microphone. 

 

*The wiring diagrams at this link show the resistor to be used for the normal wiring, not the red dot wiring, which is backwards from the notes above. I'm confused. https://sanken-mic.com/en/qanda/index.cfm/11.20

The UM400 was pre-servo bias(UM400a is servo bias), so if a mic was wired to work with the 400(and also not universal), that would cause issues with a servo bias transmitter(LMa is servo bias, as well).  And I could be wrong, but I do not believe the MM400C is servo bias, so any mic wiring advice applied from that would be in contradiction to what is needed/optimal for a UM400a, LMa or any other servo bias transmitter.

 

I would definitely make sure to get a lav wired specifically for servo bias and give the system another shot.

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4 hours ago, Paul F said:

I read up on the red dot COS-11D. From Lectrosonics back in 2012:

 

"We recommend wiring the standard level COS-11 in a 2 wire configuration with a 1k resistor in series with the white wire (source wire) to ground. This reduces the output of the standard mic by 6 dB which will prevent overload of the input buffer on the UM400. This isn't necessary for the SM series since it cannot be overloaded by the COS-11 under any circumstances. It does make the microphone compatible with both transmitter series."*

 

From a member of JW back in 2012, "When I purchased two of the red dot COS-11's a few years ago, it was at the advice of my sales contact at LSC -- I had also purchased two Lectro MM400c's, and it was explained to me that with this particular TX, the RF gain was somehow tied to the main output level of the unit -- thus a higher gain setting on the TX delivered better RF performance... the 10dB pad built into the red dot COS-11 was essentially meant to compensate for the higher gain setting on this TX."

 

I don't know how any of this applies to the LMa I was provided, but it's clear that the red dot was provided to improve performance of some Lectrosonics transmitters, not to be used in loud situations. So for all I know, I was provided the correct microphone. 

 

*The wiring diagrams at this link show the resistor to be used for the normal wiring, not the red dot wiring, which is backwards from the notes above. I'm confused. https://sanken-mic.com/en/qanda/index.cfm/11.20

All I know is, I use red dots on UM400s and SMQVs when people are yelling, and it definitely saves the dialogue. I can't speak to the LMa. Try your test with a non-red dot, servo bias and otherwise.

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  • 5 months later...

So I think I may have figured this out... I think it is the F8 headphone amp, which is known for not being great, that is coloring the sound. When I pulled up a side by side recording of the the 411a/UM400a vs the G4 on the computer with good monitors, the noise floor difference was gone. In fact, the Lectros were just a hair better. @Paul F

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