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ADA4075-2 and SSM2167 Q's

Hi,

We are looking at using the ADA4075-2 instead of the OP275, as recommended by ADI, as a balanced line driver to the AD1974. However, the reference design uses trimpots whereas these are not shown for the OP275 reference design. As we are looking to have 12-16 inputs per PCB, it isn't feasible to tune each individual trimpot. Can these be left out or are there standard resistor values which are used which produce 'good enough' results.

Further to this, there are in some places specifications for the ADA4075-2 and SSM2167 in the datasheets as to what type of capacitors to use, however not always. I was wondering for a general idea of what types of capacitors are suitable for these devices. I have read conflicting information about how 'bad' ceramic capacitors are in audio etc and just want to get some device specific info.

Thanks

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  • Thanks for the reply.

    The design I am looking at is in the ADA4075-2 datasheet. The system will consist of either an electret microphone or a ADMP504 mems mic being preamped using the SS2167 then feeding into the ADA4075-2 and finally the AD1974. I haven't looked at the p-p etc for the different mics yet, so I can look at these details tomorrow maybe. An aside question, is it always necessary to use a preamp, like the SS2167, or is it possible to feed the mic output straight in to the ADA4075-2 amplification and increase the gains in this stage?

    Regarding the electrolytic caps, what are your thoughts on aluminium vs tantalum? Aluminum seem to be more prevalent - is this just a cost factor? Also, excuse my lack of knowledge on this, but with the metal film caps - what specific types are used in audio (maybe an example part number or something would help a bit - lots of caps out there) and what sort of difficulties arise with the SMD packages?  Are they used mainly for the coupling or filter portion of the audio path?

    Thanks for the thorough answers to both posts!

Reply
  • Thanks for the reply.

    The design I am looking at is in the ADA4075-2 datasheet. The system will consist of either an electret microphone or a ADMP504 mems mic being preamped using the SS2167 then feeding into the ADA4075-2 and finally the AD1974. I haven't looked at the p-p etc for the different mics yet, so I can look at these details tomorrow maybe. An aside question, is it always necessary to use a preamp, like the SS2167, or is it possible to feed the mic output straight in to the ADA4075-2 amplification and increase the gains in this stage?

    Regarding the electrolytic caps, what are your thoughts on aluminium vs tantalum? Aluminum seem to be more prevalent - is this just a cost factor? Also, excuse my lack of knowledge on this, but with the metal film caps - what specific types are used in audio (maybe an example part number or something would help a bit - lots of caps out there) and what sort of difficulties arise with the SMD packages?  Are they used mainly for the coupling or filter portion of the audio path?

    Thanks for the thorough answers to both posts!

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