New Official Kit V2+: Audio Input is here!

https://www.hifiberry.com/shop/boards/hifiberry-dac-adc/

The adc had texted wrapped . . . . . D’Oh.

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This is a formidable news !
Congratulation to you and the team that made this possible.
What would be required to upgrade from the V2 kit ?
Is it just about the case and HiFiBerry or is there more to it ?

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Exactly. It’s just the case and the Hifiberry, but you can make a simple hole to your current aluminum case and it should be enough for the HB’s audio-in mini-jack. I could give you a technical plot :wink:

Of course, if you prefer a new case, with holes for the stereo audio-in mini-jack and a balanced audio-in jack (mono), you are very welcome to buy it in the zynthian shop :relaxed:

The HB DAC+ADC is also available in the zynthian shop, with the extra 40-pin connector soldered on it.

Regards,

So both 40 pin sockets are populated with connectors?

A female connector for plugin on top of the RBPi and a male connector for connecting the zynthian’s ribbon-bus-cable. You don’t need to solder anything :wink:

Does it support balanced dynamic microphone? Could add an XLR to front / top of Zynthian and use a gooseneck microphone as input. (Great to see audio input promoted - has many use cases.)

Yes, it support it, but the pre-amp gain is only 12db, fixed for balanced input.
When using not-balanced inputs you can choose between 0, 12 & 32 db.
Take a look to specs:

https://www.hifiberry.com/build/documentation/datasheet-dac-adc/

Regards,

That is what I thought. Not ideal but a good off-the-shelf solution even with that limitation. (It seems strange that they don’t support balanced mic input! Maybe feedback to them might improve this.)

But it’s supported!! did you read the specs?

https://www.hifiberry.com/build/documentation/using-dynamic-microphones-with-the-dac-adc/

Regards,

I did indeed read the spec which is why I feel they missed a trick. They recommend using the unbalanced input and high gain setting in the preamp. This will work for many use cases (and may be sufficient for a zynthian with short interconnect, e.g. physically attached, vocoder-style microphone) but it would be great if one could plug a balanced microphone directly into a zyncoder to process vocals. Of course there are lots of solutions and maybe most users would prefer to run their microphones to a mixer and put the zynthian in an insert point or effects send loop. I am just wishing for perfection. The JACK Audio Connection website has a lovely statement, “Of course, a lot of people don’t live in an ideal world, and believe that software should make up for this.” I am going to be quoting that a lot in the future…

But there is the possibility of using a lower gain (12db) with balanced input. Anyway, i will test in the next days and will give feedback about it … :wink:

Regards,

I have the issue that I need phantom power. That’s why I take a mixer anyways right now. The Audioinjector Ultra has balanced input as well

Response from Daniel at Hifiberry to my query:

balanced input with 32db gain isn’t supported

so yes, it will work with a high output microphone but not with most dynamic mics which require ~40dB gain nor with condenser mics that require phantom. I am still really glad that the new kit supports audio input and look forward to hearing of peoples experience with it. Well done @jofemodo for enhancing the product. It’s getting better all the time…

Yes, this is pretty clear in the specs … so for using a low output mic with the balanced input, an external pre-amp is needed. Same for phantom devices.

You are very welcome, my friend! I hope to improve it yet more in the future … :wink:

Regards,

These are typical gains used for some popular dynamic mics:

shure

  • sm58 - 24dB (default setting)
  • sm57 - 22db
  • v300 - 21db
  • pg58 - 22db
  • pg48 - 21db

sennhesier

  • E935 22db
  • E835 23db

Of course, if you sing with the mic very close to your mouth, 12db could be enough :wink:

Is the ADC actually handling a balanced input, or is it just using an adapter to convert balanced to unbalanced?

The Hifiberry DAC+ ADC uses a PCM1861 for analogue input. This supports differential (balanced) input at 0dB or 12dB gain, i.e. it is the ADC chip which is handling the differential input, not an external preamp. These gains are for different physical inputs selected by jumpers. It seems that Hifiberry have only wired the 12dB balanced inputs to the header hence 0dB balanced input is unavailable. That seems a little odd as it is neither line level nor mic level, the former is available on the chipset, the latter is not. I am sure this must meet the majority of use case they are trying to serve.

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Hi @riban (or whoever knows about this subject :wink: )

Do you think a decent" active DI" unit could be a good (enough) complement for connecting HB’s 12dB balanced input to standard dynamic mics and electric guitars?

Thanks,

Grrrr! I wrote a long, full response and that response was lost. I must remember to stay away from Zynthian Discourse in the morning when it is still waking up, stretching its arms and before its first coffee. (I believe Discourse is sluggish because its host server is busy building nightlies.)

Anyway, the gist of what I wrote is: We should consider use cases. Balanced (differential) inputs help to reject common mode interference on long cable runs, electrically noisy environments or low signal levels. The signal is soon converted back to single reference so there is limited use of using a DI + balanced inputs if the unbalanced inputs are available. Impedance matching is an important element in reducing hum, buzz, noise, etc. Balanced inputs are traditionally lower impedance than unbalanced inputs. Guitars expect a high impedance input whilst microphones often expect a low impedance input. I don’t really understand the design principals used for the HB input. It does not align with traditional levels / impedance / differential input / etc. so I find it difficult to advice how best to interface with it.

A DI can provide impedance and level matching but this may alreadty be available with the inputs of the HB. If the HB accepted balanced inputs with varying gain / attenuation then a DI would make sense although a switch might be as good, changing the input configuration. Tricky to say without playing with one. It is a little too much for me to justify buying. I really like the idea of audio input to the Zynth but want to implement the most flexible solution without spending too much.

(I feel frustrated that this response may be missing elements from my lost response but I do need to work so here it is!)

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Thanks a lot for your answer … i hope to do some deep testing very soon with different microphones and electric guitars to determine the best way of using the HB DAC+ADC input. Then, probably i will come back to you with more questions :wink: