2k Trim Pot

[MTCA]

Hi!

I'm new here... I've been reading on this forum for a while now, but this is my first post...  Consider me as a newbe..

I need a 2k Trim Pot for my Ross Comp-project, but I can't get my hands on one... I'm ordering from Banzai, and they don't have such a thing.. Is there any other methods of getting a 2k trim pot without using a normal pot, or can i use a 2,5k for example?

[frokost]

If you do a search you'll find that you problably don't need one. I did that and ended up with two 1K resistors instead. Works perfectly.

[96ecss]

Hi and welcome. 2.5K should work fine. What pedal are you building?

Dave

[markm]

The modern 3080's seem to work fine with 2 1K resistors.
Metal can 3080's perhaps not but, the others are fine like the Harris 3080E's.

[Mark Hammer]

1) What the pot says it is and what it is can be different, within the specified tolerances.  So, a 10% tolerance on a 2.5k pot means it can be anything between 2.25k and 2.75k.  You will note that 2.25k is pretty dang close to 2k plus a 10% error.

2) Most folks who have diddled with it find that a pair of 1k resistors "works".  I suppose ideally one would measure things on a scope and fine tune the trimpot for optimum performance.  But let's be honest here.  Are you going to use a scope?  Probably not.  If you're going to tune it be ear, will you be able to hear the teensy-weensy distinctions between a perfect set-up and an acceptable setup?  Nah.  If there was a wide range of possible settings, that would be one thing, but the ideal is so frequently close to the midpoint on the trimpot that a pair of 1k resistors is virtually guaranteed to be within spitting distance of an optimum setup for most folks.  I might point out that bucket-brigade chips are also supposed to use a trimpot to match their two complementary outputs for optimal clock noise rejection.  While some companies use a trimpot, the overwhelming majority just use two equal-value resistors to function like a trimpot set to the midpoint, just like in the Dynacomp/Ross situation.  I suppose it might help if the two resistors were 1% types, but then again maybe even that is going overboard.

There's a reason why the phrase "Close enough for rock and roll" exists.

[96ecss]

Hi and welcome. 2.5K should work fine. What pedal are you building?

Dave

I don't know how I missed the part about the Ross Comp in his post. 

I need to pay better attention sometimes.

Dave

[MTCA]

The modern 3080's seem to work fine with 2 1K resistors.
Metal can 3080's perhaps not but, the others are fine like the Harris 3080E's.

3080's? 

Thanks to everybody else... So, should I go for the 2,5k trim pot or two 1k resistors..? I'm kind of new to this.. 

And, No, I'm probably NOT going to be using a scope... 

Thanks again..

[markm]

3080's? 

Yeah.
The IC that the Dyna/ROSS Comp circuit uses.

[petemoore]

So, should I go for the 2,5k trim pot or two 1k resistors..?
  I think either one will work fine.
  You probably wouldn't tell any difference.
  To tell what kind of range that parameter makes I'd start with the 2k5 pot, I'm not sure what difference the extra .5k would make...
  you might be able to cobble a trimpot trim resistor across the outside lugs, perhaps just above board [with a 'u-turned' resistor] or below board.
  To arrive at a 2k pot, hook the wiper and an outside lug of a 10k pot across your 2k5, adjust until the paralleled resistors = 2k, lift and measure the resistance you adjusted the 10k to, replace the 10k with a fixed resistor of ~same value.
  More trouble than I'd go to, I'd use the 2k5, adjust a little bit, leave set.

[the recluse]

There's always futurlec (just make sure to do a search for futurlec on the forum before placing an order so that you know what to expect)

2K horizontal trimmer