[AudioI] People Digest, Vol 25, Issue 5

Thu Feb 10 15:46:04 UTC 2022

Hi Matt,

A microphone pre-amp would indeed be very interesting for one of my projects:
- phantom power 48V integrated, but controllable via GPIO 
- a gain potentiometer is also necessary, also preferably controllable via GPIO
- It would be nice to have the print directly soldered on an XLR-port so that it is easy to install into a chassis like this: https://www.electronics-lab.com/project/tiny-proffesional-microphone-preamplifier/

Kind regards, 

David

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Today's Topics:

   1. Re: Microphone preamplifier (Matt Flax)
   2. Re: Microphone preamplifier (Ivan)

----------------------------------------------------------------------

Message: 1
Date: Wed, 9 Feb 2022 22:10:21 +0000
From: Matt Flax <matt at audioinjector.net>
To: Ivan <probecomp2 at googlemail.com>, people at lists.audioinjector.net
	<people at lists.audioinjector.net>
Subject: Re: [AudioI] Microphone preamplifier
Message-ID:
	<0100017ee0899c3f-e3054610-af75-4f45-bb82-f22f6558c27c-000000 at email.amazonses.com>

Content-Type: text/plain; charset="utf-8"

Good to hear. The microphone preamplifier has been started - however there are a couple of other preamplifiers in line as well.

I am keen to get ideas on different use cases for this card. For example, I would imagine that people would want the phantom feature. But what about dynamic microphones ?

Matt

On 9/2/22 21:21, Ivan via People wrote:

Hi Matt,? 

I would be very interested in the mic preamp if you were to design one, as I don't have the expertise...?

Is such a product on your roadmap? If so, how long do you expect it would take you to be able to offer it??

Regards,

Ivan

On Tue, Feb 8, 2022 at 9:46 PM Matt Flax <matt at audioinjector.net <mailto:matt at audioinjector.net> > wrote:

 Hi there,

 The XLR preamplifier is setup to carry up to around 20.4 V (about 19.4  dBu). The output preamplifier has a gain of 13 dB. The input  preamplifier has a gain of -12.8 dB.

 A good microphone preamplifier would require both phantom power (the 

 power rail is available on the Pro and Isolated soundcards) and also a  significant input gain of around 30 dB.

 It would be great if enough people were interested in this to either 

 design their own together, or given more time I can design one up.

 Matt

 On 4/2/22 21:24, Ivan via People wrote:
 > Hello,
 >
 > I have a need to connect professional (condenser) microphones to the  > Raspberry Pi and I was wondering if I can use the XLR preamplifier 

 > with the Pro sound card, to do that?
 >
 > I've noticed that the sound card has the phantom power available, but  > I'm not sure if the XLR preamplifier has access to that and whether  > the gain is sufficient?
 >
 >
 > Thanks,
 > Ivan
 >
 --
 Checkout the community email list :
 https://lists.audioinjector.net/mailman/listinfo/people

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Message: 2
Date: Thu, 10 Feb 2022 12:27:49 +0100
From: Ivan <probecomp2 at googlemail.com>
To: Matt Flax <matt at audioinjector.net>
Cc: "people at lists.audioinjector.net" <people at lists.audioinjector.net>
Subject: Re: [AudioI] Microphone preamplifier
Message-ID:
	<CAAOPoqRi1JhQno1tVYm=B8-W2Ow_tppbmS27=OpG9cEoTBwtbA at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

The microphone pre-amplifier would need to accept both dynamic and condenser studio microphones.

Ideally, the phantom power (+48V) could be turned on or off via the software driver. This would be ideal. If this is too complicated to develop, than a physical jumper on the board would do a job, preferably available independently for each (left/right) channel, so that the different types of microphones can be used at the same time.

Gain should also be sufficient, to raise the low microphone level.

This is just a suggestion (considering you've already started the
development) but potentially, the XLR board could be modified so that it can be used as both a line input, or a microphone input (with switchable phantom power). This would make it simpler to manufacture (one board, instead of two) and the product itself more versatile for various applications.

Regards,
Ivan

On Wed, Feb 9, 2022 at 11:10 PM Matt Flax <matt at audioinjector.net> wrote:

> Good to hear. The microphone preamplifier has been started - however 
> there are a couple of other preamplifiers in line as well.
>
> I am keen to get ideas on different use cases for this card. For 
> example, I would imagine that people would want the phantom feature. 
> But what about dynamic microphones ?
>
> Matt
> On 9/2/22 21:21, Ivan via People wrote:
>
> Hi Matt,
>
> I would be very interested in the mic preamp if you were to design 
> one, as I don't have the expertise...
>
> Is such a product on your roadmap? If so, how long do you expect it 
> would take you to be able to offer it?
>
> Regards,
> Ivan
>
> On Tue, Feb 8, 2022 at 9:46 PM Matt Flax <matt at audioinjector.net> wrote:
>
>> Hi there,
>>
>> The XLR preamplifier is setup to carry up to around 20.4 V (about 
>> 19.4 dBu). The output preamplifier has a gain of 13 dB. The input 
>> preamplifier has a gain of -12.8 dB.
>>
>> A good microphone preamplifier would require both phantom power (the 
>> power rail is available on the Pro and Isolated soundcards) and also 
>> a significant input gain of around 30 dB.
>>
>> It would be great if enough people were interested in this to either 
>> design their own together, or given more time I can design one up.
>>
>> Matt
>>
>> On 4/2/22 21:24, Ivan via People wrote:
>> > Hello,
>> >
>> > I have a need to connect professional (condenser) microphones to 
>> > the Raspberry Pi and I was wondering if I can use the XLR 
>> > preamplifier with the Pro sound card, to do that?
>> >
>> > I've noticed that the sound card has the phantom power available, 
>> > but I'm not sure if the XLR preamplifier has access to that and 
>> > whether the gain is sufficient?
>> >
>> >
>> > Thanks,
>> > Ivan
>> >
>> --
>> Checkout the community email list :
>> https://lists.audioinjector.net/mailman/listinfo/people
>>
>>
> --
> Checkout the community email list 
> :https://lists.audioinjector.net/mailman/listinfo/people
>
>
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