Marshall JCM 800, Series 2000, Cross Channel Interaction

[Helmholtz]

Ok... so we have a voltage divider and my assumption is the 5K pot will allow for a greater signal to pass through - correct? So why not have that value is the previous revisions (unless an oversight)? Just curious.

I also assuming too much signal will overdrive the next stage. I just need to answer the question... do we leave the 1K in the amp or change it out (because there is something to gain by doing so).
Thanks.

I think I answered your previous question.
You decide if you want/need more or less available gain.
Of course turning down the pot will always lower the signal and the gain.

[Helmholtz]

It's probably not going to be a radical difference.

Difference with pot fully up is at least a factor of 4.
But as the source impedance of the preceding circuit adds to the 22k, it might be close to 5 or 14dB.

[TomCarlos]

Thanks Dude and Helmholtz.

[The Dude]

Difference with pot fully up is at least a factor of 4.
But as the source impedance of the preceding circuit adds to the 22k, it might be close to 5 or 14dB.

What I meant, and admittedly poorly stated, was that it would just mean the volume pot would be in a different spot in it's rotation for a similar output. But, of course you are right that if the pot is fully up, there would be a pretty good difference in level. Since Tom earlier said there was a difference in the "sweet spot", I assumed we weren't talking about maxing the pot.

Edit: In other words if you can get to the customer's "sweet spot" with the 1K pot, I wouldn't bother changing the pot. On the other hand, if the pot is maxed and you still can't get to the sweet spot, consider changing the pot. Otherwise, it's just a number on a dial.

[Helmholtz]

Since Tom earlier said there was a difference in the "sweet spot", I assumed we weren't talking about maxing the pot.

Ok, I understand.
Funny thing is we don't have a translation for "sweet spot" over here.
In fact I never really got the idea behind as the term seems to assume that there must be one well discernable optimum setting - which as a general concept I refuse to believe.
If the sweet spot was well defined it could be measured.

One more remark:
As the pot value kind of limits the max. send level, it might make sense to use a lower value to avoid overdrivng the effects unit (for users who like to turn pots fully up)
OTOH, if the send level is too low, the effects return level might be low as well..
But that's something to be tested.

[The Dude]

I think "sweet spot" is user defined- a different spot for different players depending on what they like. A jazz player would have a different "sweet spot" than a metal player. At any rate, I apologize for my vague post. When I said there would be "no radical difference", I meant that the sound would likely be the same, but the dial reading would be different. Of course, if the user is maxing the pot, that's another story.

[Helmholtz]

Needless (maybe) to say, you could always use the 5k pot and wire a parallel resistor across its outer lugs to limit the range.

[g1]

So why not have that value is the previous revisions (unless an oversight)? Just curious.

Often, changes like this are due to user feedback. Another consideration is it is right before the FX loop. Perhaps there was not enough drive available into some FX units?
Or maybe with lower gain settings, people were having to turn the volume way up?