Resistance difference on left / right channel RCA center pins, what's up?

[eric.hedman]

I'm a new crack-head and totally addicted, this is a wonderful product/project, thanks for making it available!!!

I've been enjoying my Crack for a few weeks and I'm ready for the speedball upgrade. I started with the resistance / voltage checks and I noticed/paid attention to that left and right RCA center pins measure differently by almost 10%.

Right: 94,8k
Left 86,5k

I continued to check the resistance after the potentiometer and it's always lower on the left channel (resistance check done without tubes installed).

At my normal listening volume the resistances after the potentiometer is:

Right: 9,7k
Left: 8,8k

The difference in voltage measurements are not that big between left and right.
1. 79,7
2. 187,7
4. 188,1
5. 80,6

7&9 both 112,3

Some stupid questions/statements;
1) I assume this mean that the left channel is always louder than the right, is that correct?
2) Is it the pot that's the culprit, or should I look elsewhere (bad solder joints? any ones in particular)?
3) If it's the pot, did I get a bad one, or is this within acceptable parameters of the component?
4) Is this a significant enough difference to be audible? I now recall music sounding a bit "off" when I accidentally had the RCA cables connected wrong (left -> right/right->left), but I just thought it was because of the mirrored stereo image. Now that I've seen the readings they started haunting me

Thanks for any help/suggestions!

Eric

[Paul Joppa]

The input resistance is the end-to-end resistance of the pot, which usually has a specification of +/-20%. Your measurements are within that spec. But what's important is the ratio of resistance at a setting to that across the full pot - in your case, 9.7/94.8 = 0.1023 vs. 8.8/86.5 = 0.1017, a difference of 0.55% or 0.05dB.

!) So no, the measurement at the RCA jack does not determine the loudness by itself

2) There is no culprit

3) Everything is in spec.

4) the actual difference of 0.05dB is inaudible

[eric.hedman]

Thanks for the explanation! I'm really learning to appreciate audio design and improving my understanding of electronics throughout this journey!
The perceived difference I experience must be due to my left and right ears having different sensitivities to some frequencies then I suppose. I tried switching left and right inputs again to compare, and indeed, there's an audible difference on some tracks/frequencies, but that must then all be my hearing and not the gear

On a side note, I completed the first part of the speedball upgrade yesterday and whoa, lo and behold, I experience the sound now "cleaner" and "wider" with "better detail" somehow.
I will continue with the second part today, can't wait to listen and see if it keeps improving