Further Volume has narrow range of effect

[paulman]

Good morning fellow Alembicster's  
 
I have had my Further for a couple of years now, and have recently noticed that the volume control on the guitar is not very expressive.  
 
For example:  if the volume control on the Further is turned down slowly while playing, the volume output does not reduce until the control is almost at the end of it's counter-clockwise travel.  The last few degrees of turn are the only position the volume control has any effect.  This response (or lack thereof) is the same with the effect loop engaged or disengaged.  The Further is running directly into the amp with nothing in the chain between them.  
 
Is there a way to make it more expressive over a greater range?  I have tried the same experiment with my Skylark, and with a PRS SE as a control and both of those guitars have an even response as the volume control is turned down on the guitar.  
 
Let me know of any ideas.  I searched the forum and couldn't find anything on this particular issue.  Thanks a ton and have a Grate and Ful day.  
 
Rog

[grateful]

Hi Rog,
 
The volume pot is basically a variable resistor so there is something wrong if it's behaving like that.  (My Further's volume pot behaves impeccably.)
 
Is the pot itself possibly turning?  If not, I think you need a new one.
 
Mark

[David Houck]

How does the output compare to the Skylark?

[paulman]

Woah...speedy responses guys.  Thanks!
 
The volume control full output is the same on both Further and Skylark, Dave.  And conversely (humor?) the output from the volume control all the way down also is the same on both guitars.
 
Rog

[mica]

That does sound like a problem with the volume pot. Take a peek inside and tell me if you can read a part number 475-XXX on the volume pot. Tell me what you find on the XXX.

[paulman]

A reply from the head Honcha...TY!
 
Mica, the part reads 475-020.  Good to hear from you.  
 
Roger

[dfung60]

Mica will tell you whether that's the right part number or not, but the description of your problem makes me think that your volume pot is linear taper instead of audio taper.  It would not be unheard of for a pot to be mismarked.
 
The perception of volume is not numerically linear.  Doubling the resistance turns out to cause only a small change in volume.  To create a perceptual change to 1/2 volume, you need to increase the resistance by a factor of 10.  This is the difference between linear and audio taper pots.  A linear taper pot linearly scales from no resistance to it's maximum.  An audio taper pot is set up so that turning the knob to halfway gives you the resistance you need to make the instrument sound half as loud.
 
David Fung

[paulman]

Thanks for that Dave.  Thats exactly what I thought was happening, but hadn't cracked the case to see that the pot is Alembic specific.  Now I realize it cannot be replaced with just any old pot off the shelf, which is ok 'cos I didn't pay for any ole off the shelf guitar anyway.  The control is still usable, just not as expressive as I'd like.  
 
But, I am totally sure we'll get it working correctly.  It's amazing to me that it would actually take me this long to realize it was a problem, as I remember it being that way back when I was testing it at the store (Ed Roman's), same volume pot action with the other Further that was there.  So natch I just assumed...
 
Thanks again for da help.  Just had a great gig and again, they always comment on the stellar sounding guitar hoorah!

[paulman]

Hiya.  Just checking to see if there's any further thoughts on the volume pot-a-rino.  
 
Thanks a ton.

[mica]

The 475-020 is a custom made audio taper pot. As David suggested, your observation is of a linear taper pot. Check to make sure the center terminal of the pot isn't shorted out. That could cause a similar result.
 
You could send me your electronics, and I can have them tested and repaired. It beats sending in the whole guitar, but even removing and then reinstalling the electronics is not a small amount of work. Keep an afternoon clear and take your time!

[paulman]

Okey dokey, did some testing after I used my new chisle to get the pot out for testing.  BTW how do I glue the wood back in?
 
Seriously...here is what I found.  
 
The following is referencing the position of looking down on the pot from the top of the control, with pin positions 1 2 3 going from left to right with the pins facing in (or towards the belly).  Used an analog multitester for basic troubleshooting.  And the control was not isolated from the rest of the electronics during testing, I could not see an easy way to take it out of the circuit.  
 
Turned fully counter-clockwise
1+2=OPEN
1+3=10k ohm
2+3=10k ohm
 
Turned fully clockwise
1+2=10k ohm
1+3=10k ohm
2+3=OPEN
 
Please let me know if that pattern is consistent with a properly working Alembic 475-020 Custom Designed Audio Taper control. (sounds official  )  
 
Thanks a ton thus far, very interesting!

[mica]

So official! Do exactly the same thing, but with the volume control at half rotation to find out interesting things. If it's linear taper, it will be 5K between 1-2 and 2-3. 1-3 should always be 10k. If it's audio taper, 1-2 should be 1-2K and 2-3 should be 8-9K.
 
When you say OPEN do you mean close to zero Ohms?

[paulman]

Ok Mica...the pot measurements at 50% read 1.5k between 1 & 2 and 9k between 2 & 3 so it's an Audio Taper pot.  Yay.  
 
Yes, I did mean close to zero ohms.  To be laughingly redundant I should have put 0k ohms  
 
Would you have another suggestion that I could try before (as #5 would put it) disassemble life form?.  
 
Thanks for the knowledge, that was kinda fun in a way.

[paulman]

Bumpity-bump.  Just wondering if there's any other suggestions before I start to dismantle my baby.  Thanks and hope everyone had a nice labor day, 'twas gorgeous in Chicago!

[paulman]

Hi, just checking to see if there are any last items I can check into before dismantling the electronics.  
 
I will have some free time this weekend, and would like to perform this operation only as a last resort.  
 
Thanks a ton for all the help so far Mica!  Luckily I have a spare Alembic so I won't be out of the game if/when the Further is down for service.  Yay