SSM2107 / ina217 Input impedence MIC / Line

[abechap024]

Hi
Quick question. I want to make the input impedance of the 2105 chip work for both MIC and Line sources. I believe they did this in the Scorpion console. but I can't find schematics for it. while I know it won't be absolutely perfect what is a good input resistor to accept both line and mic? It works fine with the 2.5k that are in the circuit right now - but I know line sources aren't seeing as high of impedance as they would like. Is that increasing distortion? noise floor?Should I leave in the 2.5k? or make them higher?
Thanks!
AC

 

[tv]

Not explicitely for your chip, but close enough:

http://thatcorp.com/datashts/dn140.pdf

fig.4

 

[abechap024]

That answers my questions, Thanks!
AC

 

[tv]

Pun intended?

 

[conleycd]

Not to consistently plug JLMaudio but it does prevent reinventing the wheel....

You can't go wrong for less than $25 the GoBetween http://www.jlmaudio.com/JLMDI.htm

This adds a 20db pad (for line), Phantom Power (and blocking if need be), and Reversal.

If you want to go a little more throw in another $35 for a high impedance instrument/line input too.

CC

 

[Bill Wilson]

I am fairly familiar with the Analog Devices product line. The SSM2105 was not familiar to me so I checked their site & did a search; there is no SSM2105. Perhaps you were thinking of the SSM2015, their first complete mike pre chip. It has been superceded by the SSM 2019.

However The THAT 1510 or 1512 have slightly better slew rate than all the others & better distortion figures & are available from Mouser.  Those who have used the THAT chips think they sound cleaner.

Just wanted to clear up any confusion on the subject.

 

[tv]

I seems that 2105 was a typo, because in the title theres 2107 and 217 which looks perfectly logical.

 

[abechap024]

oh duh! Sorry I meant ssm2017, I can be a butter finger sometimes. But I think I've decided to leave in the 2.5k resistor, put in a 10k pot for the gain and just use the same XLR input for the mic/line. the SSM chip should be able to handle the gain differences. It won't be perfect but it should function just fine, right?. I would add better switching options but face plate area is limited. So If anything else I'll test it ou...after I get some parts I've been waiting on...
cheers