Jump to content

impedence matching question


Recommended Posts

I now have a Focusrite Scarlett 2i2 audio interface that I'm using between my Simaudio MOON 310LP phono stage and my computer to enable me to have access to DRC with my LP playing.

 

I have the choice of two inputs into the Scarlett—one with an input impedance of 3K and one with 60K. The output impedance of the phono stage is 50 ohms. I'd really like to use the 3K input due to its better specifications and the fact that I can use the XLR input plug directly without the XLR to balanced TRS converter needed for the 60K input. The less than ideal TRS connection may also be a factor.

 

Would there be any issue using the 3K input with respect to the low impedance? Would I be able to hear any difference? (So far it sounds OK but a real comparison is difficult because I have to get behind the unit and spend some time changing things to swap inputs.)

 

Thanks for any help with this.😀

 

Edited by GregWormald
Link to comment
Share on other sites



@GregWormald

3kohm load impedance should be fine with 50ohm output impedance, 1 to 60 impedance ratio is fine, they "say" 1 to 10 is barley discernable, so long as that output impedance stays 50ohm from 20hz to 20khz, it "could change if it's capacitor coupled output"

"If" the capacitor is not large enough, it can get higher impedance in bass if too small in capacitance, and therefore start to effect the low bass.

 

Cheers George

Edited by georgehifi
  • Thanks 1
Link to comment
Share on other sites

Outcome—

 

I bit the bullet and I went ahead and did a comparison despite the hassle of doing so. After two back and forth listens there was no doubt in my mind (and ears🙂) that the conversion and using the 60K input gave superior, smoother, and less fatiguing sound. It was obvious.

 

So despite the very high quality XLR plugs and the definitely standard quality converters the conversion to the TRS input is the way to go. <shrug>

Link to comment
Share on other sites

46 minutes ago, GregWormald said:

Outcome—

 

I bit the bullet and I went ahead and did a comparison despite the hassle of doing so. After two back and forth listens there was no doubt in my mind (and ears🙂) that the conversion and using the 60K input gave superior, smoother, and less fatiguing sound. It was obvious.

 

So despite the very high quality XLR plugs and the definitely standard quality converters the conversion to the TRS input is the way to go. <shrug>


My manual says that only microphones should be connected via xlr and instruments and line level sources must connect via TRS. 
 

connecting a line level source via xlr will overload the preamp and result in distortion. 

Link to comment
Share on other sites

7 minutes ago, davewantsmoore said:


My manual says that only microphones should be connected via xlr and instruments and line level sources must connect via TRS. 
 

connecting a line level source via xlr will overload the preamp and result in distortion. 

Yes, I read that, but I phoned their help line (twice!) and they assured me that if no overload was present then either input would work. I had to reduce the output of the phono stage to avoid overload even on the TRS input and the input levels appeared fine on the app but the two inputs sure sounded different. There must  be something else going on.

Edited by GregWormald
Link to comment
Share on other sites



7 hours ago, GregWormald said:

There must  be something else going on.

 

"If" there were no gain difference, or cap coupling problem as I outlined.

Then there should not be any difference. As a 1-60 vs 1-1200 impedance ratio would have no differing effect to the ear, there must be different active input circuitry on the Focusrite Scarlett 2i2 audio interface inputs creating the difference you hear. (or maybe one is a cap coupled input?)

 

Cheers George

Edited by georgehifi
Link to comment
Share on other sites

  • Recently Browsing   0 members

    • No registered users viewing this page.




×
×
  • Create New...
To Top