New Official Kit V2+: Audio Input is here!

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:


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:


These are typical gains used for some popular dynamic mics:


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


  • 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?


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:

A strange development. I have just replaced the DAC+ in my Zynthian with a DAC+ ADC.

I checked the datasheets on the Hifiberry website to refresh my memory about configuring balanced input. That information no longer appears in the datasheet. Well, I submitted a query and received a reply from Daniel.

According to Daniel, the earlier information was a “mistake” and the DAC+ ADC does NOT support balanced input. This will apparently be a feature of the upcoming (and likely more expensive) DAC+ ADC Pro. A little disappointing if this is correct.

For microphone input, in any event, I would probably prefer to use a proper microphone preamplifier, giving complete control over the gain, and phantom power for microphones which need it. For balanced line level input, I could implement a simple passive solution using transformers (I have a pair of nice Lundahls unused in a box).

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Whoaooo! I just sent an email to Daniel to find out an explanation.
I will keep you informed …

I just answered this to a @Gadger, who was asking about the “Hifiberry DAC+ADC” and the recently modified specification:

As i told you, I wrote to Daniel and he told me that, effectively, the initial specification was wrong and they simply changed it… :astonished: (no comments).

But my mission is to improve zynthian, so …
FYI, from the last week, all zynthian kits include the “DAC+ADC Pro” that has a true balanced input. I will write about it very soon … when i’m sure that the specification doesn’t change :wink:



Regarding this: Hifiberry have changed the specifications for DAC+ADC. At first, they told that there was an onboard Balanced Input connector, but very recently they changed the DataSheet. Although, AFAIK, they have not officially communicated the problem, i know that there is a problem with this model and the supposed “Balanced Input” works like a simple “Unbalanced Input”.

Hmmm. I suspect that in several countries, this sort of conduct might be in breach of trade practice law. With applicable remedies. Basically, selling a product which does not work as advertised, or is not fit for purpose, etc.

Oh well. For the practical person, there are workarounds.

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Hi @jofemodo. The Zynthian shop shows the standard card, not the pro available as a spare part. Will you be changing the spare parts to the Pro card?

Here in the United States the Federal Trade Commission would have this under false advertising.

False advertising is advertising for products or services that misleads consumers, whether the act was deliberate or not.

Oh well, may need one of these:
Ballanced input circuit.

That company has a lot of cool DIY audio circuits.

Its just sad that I paid more than the pro for the non pro. When looking at the price on the HifiBerry site.
hopefully you can negotiate a deal with them. Perhaps a replacement, or deeply discounted pro for half price or such.

I’m really sorry for the inconveniences! Understand that this problem is completely out of my control. I’m a simple re-seller …

I completely agree with you. I don’t like the way HifiBerry managed their problems with the DAC+ADC.
I discussed with them and finally they offered to me a good discount for the next order. As we have changed to “Pro” version, i can offer the upgrade to “Pro” with the same discount (35%) to all users that bought the DAC+ADC in the zynthian shop. I would pay the shipping. It’s all i can do without breaking my pocket, guys.

Best Regards


Hopefully everyone here realizes this.

And let’s be realistic… This is not a situation like the Takata air bag.

Your offer is generous, and I’m sure that some users will gratefully accept. I suspect that others will not be at all concerned. There are plenty of DIY solutions for balanced input (and output) that won’t hurt the bank account. And the Hifiberry works very well in all other respects, it seems.

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Thanks for your understanding.
Please, those kit buyers wanting to upgrade to “DAC+ADC Pro”, simply send me a private message and i will give to them a promotion code.