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Multi pattern LDC with high output £300?

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Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 10:55 am
by dickiefunk
Hugh Robjohns wrote:In that case a phantom-passing gain booster might well be all you need.

H

I’ve got a pair of the Triton Fethead Phantom which I’ve tried but haven’t noticed any reduction in hiss when matching the output?

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:08 pm
by ef37a
dickiefunk wrote:
Hugh Robjohns wrote:In that case a phantom-passing gain booster might well be all you need.

H

I’ve got a pair of the Triton Fethead Phantom which I’ve tried but haven’t noticed any reduction in hiss when matching the output?

You have got this old bloke confused again!

What is your MO for comparing noise levels? The Fetheads give 18dB of gain iirc? So, are you saying when the Fethead is in circuit AND you reduce the peramp gain to match the straight through gain there is no reduction in hiss?

Dave.

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:21 pm
by Zukan
Anyone here tried the matched pair (LCT 040) from Lewitt?

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:24 pm
by dickiefunk
ef37a wrote:
dickiefunk wrote:
Hugh Robjohns wrote:In that case a phantom-passing gain booster might well be all you need.

H

I’ve got a pair of the Triton Fethead Phantom which I’ve tried but haven’t noticed any reduction in hiss when matching the output?

So, are you saying when the Fethead is in circuit AND you reduce the peramp gain to match the straight through gain there is no reduction in hiss?

Dave.

Yes that's correct

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:29 pm
by ef37a
dickiefunk wrote:
ef37a wrote:
dickiefunk wrote:
Hugh Robjohns wrote:In that case a phantom-passing gain booster might well be all you need.

H

I’ve got a pair of the Triton Fethead Phantom which I’ve tried but haven’t noticed any reduction in hiss when matching the output?

So, are you saying when the Fethead is in circuit AND you reduce the peramp gain to match the straight through gain there is no reduction in hiss?

Dave.

Yes that's correct

Weird!

Dave.

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:45 pm
by Hugh Robjohns
ef37a wrote:Weird!

Not really... it just means most of the noise is coming from the mic or the ambient acoustic sound, rather than the preamp itself.

H

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:48 pm
by ef37a
Hugh Robjohns wrote:
ef37a wrote:Weird!

Not really... it just means most of the noise is coming from the mic or the ambient acoustic sound, rather than the preamp itself.

H

But that is 'pre pre'. If he reduces the pre amp gain (by ~18dB) why does that not decrease?

Dave.

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 12:56 pm
by Hugh Robjohns
There's the same gain overall from mic to speaker... more from the fethead, less from the interface pre.

H

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 2:26 pm
by ef37a
Hugh Robjohns wrote:There's the same gain overall from mic to speaker... more from the fethead, less from the interface pre.

H

Nope, head is still not round this. I see a 'chain': mic>Fethead> pre> DAW meters. If the noise (total) is coming from the mic and you 'link out' the Fethead the noise must drop by ~ 18dB. If it doesn't then the noise is in the pre amp?

In other words, if the Fethead does not improve the overall signal to noise ratio, what good is it doing there?

Dave.

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 3:34 pm
by Wonks
Let's say Mic pre on its own provides 60dB gain to get the necessary signal level. Putting the Fethead in the line adds 27dB gain, so Mic pre only need to provide 33dB gain to get the same end signal level.

End result is the same noise level, so the noise produced by the mic-pre and the Fethead are insignificant compared to the noise from the mic (plus background noise picked up by the mic).

If the mic pre was itself notably noisy at 60dB gain (compared to the mic & background noise), then the Fethead would improve matters, but in this case it doesn't.

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 8:06 pm
by Hugh Robjohns
ef37a wrote:In other words, if the Fethead does not improve the overall signal to noise ratio, what good is it doing there?

None at all in this specific situation, apparently... Other than increasing the available total overall max gain.

It would only improve the overall SNR if the main preamp was quieter at a reduced gain setting compared to its max gain setting, which might apply to some preamps, but certainly not all.

It would appear in this case that either most of the noise is from the source (the mic itself, or acoustic noise), or it's from the main preamp and remains consistently high at a wide range of gain settings. Either way, the Fethead isn't providing a solution here, sadly.

H

Re: Multi pattern LDC with high output £300?

PostPosted: Sun Dec 22, 2019 11:18 pm
by James Perrett
dickiefunk wrote:
Hugh Robjohns wrote:In that case a phantom-passing gain booster might well be all you need.

H

I’ve got a pair of the Triton Fethead Phantom which I’ve tried but haven’t noticed any reduction in hiss when matching the output?

Which is pretty much what I'd expect with A&H preamps. Even the humble Zed range of mixers manage an EIN of -127dBu which typical of a high quality preamp and only a couple of dB higher than the very quietest preamps. Unfortunately I couldn't find a noise spec for your mixer but I'd be surprised if it was worse than the Zed.

Looking at the AT4040's specs I would expect the microphone's noise to swamp the preamp noise.

Re: Multi pattern LDC with high output £300?

PostPosted: Mon Dec 23, 2019 1:45 am
by ef37a
Yes James, I have a "humble" ZED 10, an early 16 bit one but I always thought the pre amps very good, certainly in terms of noise.

I was surprised that the OP's pres were at one point considered too noisy for the application but not having the data to hand, kept shtumn,

Dave.

Re: Multi pattern LDC with high output £300?

PostPosted: Mon Dec 23, 2019 12:47 pm
by Hugh Robjohns
It all goes back to Dickie's comment:

dickiefunk wrote:To be honest the only hiss I get is when I crank the gain on the preamps of the QU-PAC.

... and his suggestion that he needed a more sensitive mic to deal with distant choirs etc.

As we have probably all experienced, some budget preamps do introduce a lot of noise at max gain. However, although I'm not familiar with the QU-PAC, as James says A&H certainly do know how to build high-quality preamps. Oddly, though, the spec sheet I found for it doesn't provide an EIN figure, just THD+N for 0 and 30dB of gain... Both of those figures are okay, but not high-end performance... And why no figure for the max 60dB gain? Odd...

The problem we have here, though, is that diagnosing these kinds of 'noise' issue remotely is very difficult.

Obviously, if extra gain is needed to compensate for distant mic placement (or low level sources) an inline gain-booster can be a very practical solution.

And if the preamp gets noisy at extreme gain settings it can help there too, by allowing a lower (and hopefully quieter) gain setting.

But if the issue is noise, and its coming from the source rather than the preamp -- either from the mic or the natural ambient acoustic -- then an in-line gain booster won't help. And we have been told it didn't help in this situation.

The only solution for a noisy mic is a quieter one... However, the AT4040 has a self-noise figure of 12dBA, and that is leaning on the noisy side for a large diaphragm capacitor mic. The best are typically around half that at 6 or 7dBA.

But it's easy to get lost in the specs... the reality is that 12dBA is very much on a par with the very best small-diaphragm capacitor mics, and probably 6dB quieter than most. The much-loved DPA 4011 has a self-noise figure of 18dBA, for example, and plenty of choirs have been recorded using that -- including by me -- without noise issues!

So, since the use of a high-quality in-line gain booster didn't improve the noise performance we can probably assume the problem is not at the preamp. And, since the mic is no noisier than many often-used alternatives we can probably assume the problem isn't really the mic either...

Which only really leaves acoustic noise as being the real problem here...

H

Re: Multi pattern LDC with high output £300?

PostPosted: Mon Dec 23, 2019 12:52 pm
by Wonks
Simply use a louder choir. Problem solved. ;)