What is up with the U87 -10dB pad?

[AlexK]

Hey guys,

Used the U87 +pad engaged on vocals for the first time today. I wondered what was going on for the first hour of the session as everything sounded murky and crunched-up at the top end. Tried disabling the -10dB pad on the mic and engaged the -26dB pad on my pre (02R96 preamps) and voila, everything sounded how I expected it.

What gives? I've done a little search around the site and couldn't find anything.

I'm just a little shocked at how big the difference is!

Cheers!

[recorder2]

Slutz please correct me if I'm wrong but I believe the pad is between the capsule and the transformer, meaning that with the -10dB engaged the signal hits the transformer in the mic less hot, meaning there will be less transformer harmonics in the signal.

It's first of all likely that your mic needs service. That description sounds bad.

But I wonder how much of the high end is from the perception of harmonics being added when the pad is disengaged? Are you recording high SPL stuff? Though this possibility is unlikely.

You didn't accidentally switch polar patterns did you? Figure 8 is duller than Omni, and Cardioid is in the middle. Or rather Figure 8 has more pronounced proximity effect, Omni has none, and Cardioid is in the middle.

[recorder2]

Also perhaps the mic pad has nothing to do with it and you were simply overloading the input stage of the preamp, which was solved by using its pad.

[vincentvangogo]

I've always felt my U67 sounds worse with the 10db pad engaged. Was never sure if it was my mic or if they all did that.

[AlexK]

Originally Posted by recorder2

Slutz please correct me if I'm wrong but I believe the pad is between the capsule and the transformer, meaning that with the -10dB engaged the signal hits the transformer in the mic less hot, meaning there will be less transformer harmonics in the signal.

Interesting idea, but this difference was greater than night and day. I really doubt transformer harmonics would cause THAT much of a difference.

Beforehand, I was adding nearly 7dB of HF shelf in PT. Afterwards, I knocked it down to something like 1.5dB. Massive difference.

Not only was the resulting sound brighter, but it was much smoother and just generally sounded less hard...

Originally Posted by recorder2

It's first of all likely that your mic needs service. That description sounds bad.

But I wonder how much of the high end is from the perception of harmonics being added when the pad is disengaged? Are you recording high SPL stuff? Though this possibility is unlikely.

You didn't accidentally switch polar patterns did you? Figure 8 is duller than Omni, and Cardioid is in the middle. Or rather Figure 8 has more pronounced proximity effect, Omni has none, and Cardioid is in the middle.

Nope, cardioid all the way, and vocals throughout the session. It's most likely the mic needs a service knowing it's history, but still, this was pretty surprising to say the least...

Originally Posted by recorder2

Also perhaps the mic pad has nothing to do with it and you were simply overloading the input stage of the preamp, which was solved by using its pad.

Unlikely, I was just recording vocals. I've heard the U87 being belted into before and this wasn't it, just like two completely different sounding mics.

Frankly, it sounded like there was a pillow wrapped around the mic with the pad engaged...

[jmikeperkins]

I have a Neumann U77 and 2 U87's and both of these mics sound a little thinner when the -10dB pad is engaged so I don't use it. The U77 does not have a transformer so more is going with the pad than just not hitting the transformer as hard. However, the difference in the sound with the pad engaged, while audible, is not drastic and the pad does not make the mic sound muddy so something else is wrong. But if everything else with your mic sounds OK, and you don't need to use the pad on the mic, then I would not worry about it.

[E.rOk.stA]

I've had a similar experience with my Phanthera. I realize it isn't a U87 but my mic has two -3db pad switches internally. Since it's a hot mic, I decided to engage them and sorta forgot about it. About a month later, I was re-tracking the final vox for my album and couldn't understand why when I A/B'd them with the original, they had less definition in the high end.

Sure enough, after going through my vocal chain, I remembered what I had done. I opened the mic, switched them back to normal and presto, everything opened up!

Same phenomonon, different mic.

[Rick Sutton]

Mic Pads- When And How To Use Them
A discussion of the U87 pad here.
I've had a pair of 87's for 35 years. I avoid using the pad as it always diminishes the sound quality IMO.

[dsl]

Posted by Klaus Heyne:

"The concept of how the pad switch on U87s, old and current, work, and therefore when to use it, is fairly simple to understand and implement:

The -10dB switch lowers the amount of voltage coming from the capsule into the input of the FET (the transistor's gate, in this case) by 10dB.
This allows you to pump 10dB more into the mic's capsule before the FET will clip/distort.

If you do not change the amount of acoustic energy that goes into the capsule and engage the -10dB switch, the output of the whole mic will simply go down by 10dB.

The first problem of using the -10dB switch:
As the mic's basic noise floor always stays the same, regardless of whether you use the pad or not (remember: the -10dB switch only reduces the amount of energy coming from the capsule, not the mic's amp gain and noise!) engaging the switch decreases the s/n of the mic by 10dB.
In other words, the mic's amp has 10dB less signal to work with, but it will still produce the same background hiss/noise.

The second problem with using the -10dB switch is the way Neumann lowers the capsule's gain: it produces ugly side effects. You are not just losing 10dB of gain, you are adding phase shift, as the pad works via negative feedback. And NFB creates time delay and audible artifacts.

The third problem with using the -10dB switch is the phenomenon that Fletcher mentioned: The K87 capsule has a tendency to mechanically distort in the high frequencies when pushed hard, just about the point when the FET starts distorting. With other words: you may engage the switch, but may not entirely get rid of distortion, because there is no way to prevent mechanical capsule distortion when too much SPLs are hitting the diaphragm, other than backing off.

All in all, I consider the pad switch on the U87 an emergency switch, to be used only in rare cases of extremely high SPL-exposure, and with the understanding that the side effects may not be worth using the pad after all, but that it may be a cleaner solution to back off the mic from the sound source, rather than padding it down.

A final word of explanation on the seemingly confusing fact that the U87A has higher output but lower head room (i.e. given the same sound source, the U87A will distort about 6dB before the old U87 will distort):

If you follow what I explained up top, namely that the limiting factor in single-FET mics, like all U87 models, is the pitifully low headroom of the FET, it will make sense that if you pump yet another 10dB more into the FET, as the U87A's capsule does (hence the higher output of the mic) the FET will poop out even sooner than on the old model. The nice gain increase of the U87A is therefore only useful in situations of moderate sound pressure level exposure.

Best regards,
Klaus Heyne"

[Ward Pike]

I have several LDC Neumanns, including a U87 and U87ai. Neither of mine exhibit this phenomenon...leading me to believe that the effect could be localized.

[Rob Ellis]

I avoid using the pad as it always diminishes the sound quality IMO

+1 on that one

[T_R_S]

I have to use the the pad only when I recording trumpet with any U87. other than that it's always off

[slaves666]

I tried the pad once. Sounded like ass.

[vincentvangogo]

I'd prefer not to use the pad, but it seems to be the only way to avoid distortion when recording a guitar amp (other than moving the mic back a few feet, or lowering the volume on the amp.) Is it standard to use the pad when close-miking an amp?

[MichaelAngelo]

Originally Posted by AlexK

Hey guys,

Used the U87 +pad engaged on vocals for the first time today. I wondered what was going on for the first hour of the session as everything sounded murky and crunched-up at the top end. Tried disabling the -10dB pad on the mic and engaged the -26dB pad on my pre (02R96 preamps) and voila, everything sounded how I expected it.

What gives? I've done a little search around the site and couldn't find anything.

I'm just a little shocked at how big the difference is!

Cheers!

All Mic pads sound worse... period.. Padding down a signals never sound as good as no pads, But if you have to pad due to overload, thats life..

[AlexK]

Originally Posted by MichaelAngelo

All Mic pads sound worse... period.. Padding down a signals never sound as good as no pads, But if you have to pad due to overload, thats life..

Agreed, but the pads on most of the mics I use seem to have a marginal effect on their performance. It's noticeable, but it's workable and can be corrected with a little EQ.

The U87 on the other hand was something different. I was really quite shocked. From such an expensive common microphone I've come to expect more.

Glad I'm not the only one finding this with the U87...

[heimaufnahme]

The second problem with using the -10dB switch is the way Neumann lowers the capsule's gain: it produces ugly side effects. You are not just losing 10dB of gain, you are adding phase shift, as the pad works via negative feedback. And NFB creates time delay and audible artifacts.


Could this noise for example be a swooshing sound (for lack of a better desription), as if somebody is breathing into it?

[vernier]

I also avoid pads for some reason, even when they're needed.
.
.

[nodatesaid]

if you own a u87 don't use the pad..simple as that.

[Bassmec]

Originally Posted by nodatesaid

if you own a u87 don't use the pad..simple as that.

If you use the old U87 as the snare lower mic, I would advise using the mic pad, the results are very nice if very slightly crunchy! but lots lots less crunchy than not using it with a hard hitting drummer.

[heshambadr]

Dear friend

Please before anything use Neumann XLR cable because it's not 3 poles like normal ones , it's 4pole one more G to the XLR chassis , please find below


******//www.neumann.com/?lang=en&id=c...sories&dbid=95

Second there s a huge difference when u use the Neumann power supply an 249 , I be tried it with many good other console +48 , it s never the same , and that's why Neumann change patern of the TLM 49-50 from the power supply,, I mean it complete then,puzzle ,,

I just think so , you can always try

******//www.neumann.com/?lang=en&id=c...sories&dbid=85

Regards