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Big drums in small spaces article SOS_2019_01

PostPosted: Fri Jan 11, 2019 9:14 pm
by forumuser910150
Hello, big thanks for the very useful Session Notes about achieving a great drum sound in small spaces. I copied the complete mic setup from this article and the recordings I made in my isolation booth sounded wonderful !

I have one question. I do not own the exact brands or types of mics as used by Mike Senior in the article, but one of them we have in common - the Neumann TLM 103. And it is this mic which I couldn't use as my "kicksnare" mic. The TLM 103 couldn't handle the amount of dB's produced by the drummer. Even with zero gain this mic produced a distorted signal. Didn't Mike had this problem with his "kicksnare" condensor in this session? Or in other sessions ?

With kind regards,
André Hage

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 1:57 pm
by Martin Walker
Hi André, and welcome to the SOS Forums! 8-)

Since yours is a rather specific mic recording query, I suspect you'll get more answers if I transfer it to our dedicated Recording: Gear & Techniques forum.

I'll leave this shadow copy here though, so you can follow it to its new destination easily.


Martin

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 2:12 pm
by Watchmaker
wow, that mic's supposed to be able to take 138db so I'd start thinking about testing it to see if it's damaged. If not, maybe there's a bad connection somewhere. I can't image your drummer is reaching that volume unless he's a deaf Samoan with a rare and fearsome snare!

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 2:14 pm
by Wonks
Or else the phantom power used isn't a full 48v supply. The lower the phantom power voltage, the less headroom you'll have (though it reads as if the 103 only works on 48v).

But was this the mic overloading, or the mic pre-amp? It's quite easy to overload a mic pre-amp with a loud source and a condenser, even set to no gain. Which is just what pads were invented for. Has your AI got pads, and if so, did you use them?

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 2:17 pm
by Watchmaker
oooh, you are wise. Been there I gather?

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 11:21 pm
by James Perrett
forumuser910150 wrote:Even with zero gain this mic produced a distorted signal.

I often have similar problems with the preamps on my Focusrite interface - but if I plug into the A&H desk or the Audient preamps everything is fine.

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sat Jan 12, 2019 11:39 pm
by Hugh Robjohns
forumuser910150 wrote:The TLM 103 couldn't handle the amount of dB's produced by the drummer. Even with zero gain this mic produced a distorted signal.

Drums produced very big transients, and close miking drums is a challenge for a lot of mics.

However, as has been pointed out, the TLM103 is rated for just 0.5% distortion at 138dB SPL which is pretty darn impressive, so while it is possible that the mic is the source of distortion, I think it unlikely.

What's probably more likely is that your mic preamp is overloading. The TLM103 is a pretty sensitive mic at 21mV/Pa. In a close-mic situation on a loud kit that means That it's going to putting out a signal level pretty close to 0dBu -- line level -- and not all mic preamps can cope with that!

In situations like this, the ideal solution is to switch in the pad in the mic... Except the TLM103 doesn't have one. The next best option is to engage the pad on the mic preamp... But I'm guessing you would have already done that if your preamp had one.

So the final option is to invest in an in-line XLR mic attenuator, and connect that between the preamp and mic. They come in a variety of attenuation values, but 20 or 30dB is normally enough. Shure make with with three switchable attenuation amounts which is very versatile.

If, with such an attenuator in place, the distortion goes away then you know the preamp was overloading.

If the distortion continues (even though the level into the preamp is now lower) then the mic is overloading...

Now that might be because the transient peak SPL is over 140dB... Or it might be that the mic is poorly. I suspect you'd know if the drums were that loud because your ears would be sore, and if the mic was poorly you'd probably hear it on quieter musical sources anyway.

But there is one other possibility to consider, which was mentioned earlier, which is that your preamp has a dodgy phantom power supply that is not able to provide sufficient current/volts to the mic. Again, its not very likely because the TLM103 has a very modest phantom current requirement, so I'd be surprised if it stressed the preamp's supply too much. Howeve, if you're running a lot of thirsty mics off the same preamp (or you have one or more faulty mic cables) then the phantom could be pulled down far enough to cause problems.

To check, substituting the preamp or using an external phantom supply will indicate which! You could also measure the voltages between pins 1-3 and 1-2 on the mic XLR if you have a multimeter. It should be about 27V and definitely not less than 9.5V!

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sun Jan 13, 2019 12:17 am
by Sam Spoons
Hugh Robjohns wrote:You could also measure the voltages between pins 1-3 and 1-2 on the mic XLR if you have a multimeter. It should be about 27V and definitely not less than 9.5V!

:headbang: Sorry Hugh, I've always assumed Spook Power is supposed to be 48V, on pro kit at least?

I do know that some cheaper/battery kit only supplies 12V or so and I know some mics are happy with that but.......

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sun Jan 13, 2019 12:29 am
by Hugh Robjohns
Sam Spoons wrote:Sorry Hugh, I've always assumed Spook Power is supposed to be 48V, on pro kit at least?

Yes, the voltage from a standard-compliant phantom supply is supposed to be 48V +/-4V, and that's what you'd expect to see if you put a multimeter across the terminals of the mic input XLR on the preamp itself. This is the 'unloaded' condition.

However, the phantom power specification says it must be supplied through 6800 Ohm (current limiting) resistors in each side of the balanced line (they also serve to prevent the power supply from loading down the mic output!) . Consequently, the current drawn by the microphone will inevitably produce a voltage drop across those resistors, reducing the actual voltage at the microphone. (The 'loaded' condition)

The TLM103 apparently draws 3mA of phantom current and, by using Ohms Law (V=IR), we therefore have 0.003x6800 = 20.4V. So that's 48V at the top of the 6800 resistor, and about 27V (48-20.7) at the bottom which connects to the input XLR socket. So it's that 27V which the mic's gets to use at its XLR pins.

If a mic draws the maximum allowed current of 10mA, the voltage available to the mic would be just 9.5V.

When I review preamps and interfaces I always check that this minimum voltage is maintained when fully loaded. Most preamps manage without issue, of course, but I reviewed one last week that didn't... And I'm pleased to say that the manufacturer has gone away to tweak the design to fix this (minor) problem.

Hope that makes sense.

H

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sun Jan 13, 2019 12:31 am
by Sam Spoons
Thanks Hugh, yes it does :thumbup:

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sun Jan 13, 2019 1:40 am
by Watchmaker
Thank you Hugh, that was gigantically informative.

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Tue Jan 15, 2019 3:06 pm
by Mike Senior
Hi André, and thanks for the kind words about that article! It was an unusual session, but it turned out well, and I'm glad it helped you improve your own recordings. :)

forumuser910150 wrote:Didn't Mike had this problem with his "kicksnare" condensor in this session? Or in other sessions ?

Well, I won't attempt to rehash any of the great information that Hugh's already provided. He's basically said everything I'd have said, only better, as usual! The only thing I'll add is to confirm that I did indeed encounter no problems at all with distortion on the kicksnare mic on this specific session, and we were recording through an Audient ASP880, I seem to remember.

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Tue Jan 15, 2019 4:03 pm
by Hugh Robjohns
Mike Senior wrote:...I did indeed encounter no problems at all with distortion on the kicksnare mic on this specific session, and we were recording through an Audient ASP880, I seem to remember.

Ah! The ASP880 has masses of headroom! As I said in my review:

SOS Review wrote:Moving to the opposite extreme, the preamp's massive headroom is revealed when I tell you that the mic and instrument inputs can accept +28dBu with the pad engaged before overloading the converter, and the line input can accept 10dB more.
https://www.soundonsound.com/reviews/audient-asp880
So that would be +18dBu without the pad engaged -- still easily more than enough to cope with the output of a TLM103 in a very noisy place!

I love it when the engineering in 'audio engineering' stacks up! :lol:

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Thu Jan 17, 2019 7:10 pm
by forumuser910150
I would like to thank everybody for the information above ! Highly appreciated !
The pre-amp I used has no pad-switch on it (RME UFX+). With the microphone itself everything is O.K, I made clean recordings with it later on. My problem with the distorted signal was overloading of the pre-amps
I will certainly go for an in-line XLR mic attenuator. I am sure that it will come in handy!

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Fri Jan 18, 2019 12:47 pm
by Hugh Robjohns
That's interesting. Specs for the RME UFX+ state that with the gain at zero the maximum mic input level is +18 dBu, which should be more than enough.

Intriguing!

H

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Sun Jan 20, 2019 10:58 pm
by Studio Support Gnome
random aside , not helpful but...


I recorded/broadcast the very same drum kit, in a MUCH larger space..... (Church sized live / broadcast venue )

Not once but twice..... Once in the hands of the same act...

once in the hands of a certain more noteworthy artiste the night he infamously got thrown off stage by the promoter ,..,..


those in the know can go find the you tube video and see the kit in situ....


I had a jolly good chuckle when I saw the article..... and messaged Mike directly.... ;)

Kit sounded alright in the hands of the youths Mike also worked with, but the drummer needed to come to physical maturity and gain better consistency in his playing / power/ control

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Tue Jan 22, 2019 7:08 am
by Mike Senior
Studio Support Gnome wrote:the drummer needed to come to physical maturity and gain better consistency in his playing / power/ control

Although, I have to say, I wish I'd been anything like that mature at that age! :) I mean, those kids have a work ethic like you wouldn't believe...

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Tue Jan 22, 2019 10:35 am
by Sam Spoons
Average age 13 and a bit, didn't he say 3rd CD? Just had another listen and I see where Max is coming from but he's damn good for 13. It's decent by any standard and a bit exceptional for their age.

Re: Big drums in small spaces article SOS_2019_01

PostPosted: Thu Jan 24, 2019 11:23 pm
by Studio Support Gnome
Mike Senior wrote:
Studio Support Gnome wrote:the drummer needed to come to physical maturity and gain better consistency in his playing / power/ control

Although, I have to say, I wish I'd been anything like that mature at that age! :) I mean, those kids have a work ethic like you wouldn't believe...


I suspect neither you or I had a Magician Uncle

;)