Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 9th August 2008, 08:27 AM   #1
diyAudio Member
 
east electronics's Avatar
 
Join Date: Jan 2006
Location: Athens GREECE
Default linear pot

i was reading somewhere that the use of linear pot for volume controls is better than the log .... but there is some resistor that you connect to it to give logarithmic behaviour ......

the think is that i have a bunch of log pots cheap meterial from radioohm or piher and like most of them have audible diference between left and right ....

any ideas ????
__________________
SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
  Reply With Quote
Old 9th August 2008, 08:58 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
stereo log pots (dual gang) have a reputation for poor matching between channels. Dual gang lin pots sometimes/often have better matching particularly at high attenuation rates.

That is the only advantage that lin has over log, but for balance of a stereo signal it is quite important.

A log faking resistor is usually added to the wiper and ground to simulate the log law over part of the travel. Unfortunately you end up with an S shape law rather than the Log law but it works.

A lin pot is usually chosen that is 5 to 10 times higher resistance than the ideal log pot and then a resistor is added that is between 8% and 15% of the lin pot value. It's worth experimenting with resistor value to hear how different values affect the turning of the volume pot.

10k log to 20k log ~= 100k lin + 8k1 to 15k resistor.

The output impedance of the lin + faking resistor is higher than the log pot. Take care.
__________________
regards Andrew T.
  Reply With Quote
Old 9th August 2008, 09:09 AM   #3
diyAudio Member
 
east electronics's Avatar
 
Join Date: Jan 2006
Location: Athens GREECE
Default thanks andrew

i will give it a try and let you know ....

yet what you said its true ......i took out something like 5 pots out of my stock ....ok they are cheap ...its not the good staff but really and especially in low levels there is audible diference and in all 5 of them

thanks andrew
__________________
SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
  Reply With Quote
Old 9th August 2008, 01:23 PM   #4
Mooly is online now Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
There is nothing worse than the stereo image shifting as you alter the volume.
How about connecting a dual gang pot to a low voltage DC supply and putting a DVM across the two wipers.
  Reply With Quote
Old 9th August 2008, 01:34 PM   #5
diyAudio Member
 
east electronics's Avatar
 
Join Date: Jan 2006
Location: Athens GREECE
Default not needed

there is no point to search in all my shop for a cheap but good stetreo log pot.....there must be almost 200 of those in my shop .....

BUT !!!! the first linear alps stero ( cheapest available) lin pot of 100k i found in the shop with a couple of metalfilm 18k sounds a lot better ....there is just a tinny diference in very very low volumes .....

Andrew T is right once more .....

though the log curve is kind of strange not what i am used to from log pots but still is very nice i think

also idont know why i thing this pot sounds better than the log any way ( may be its just my idea )

thanks
__________________
SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
807 E-Linear Fuling Tubes / Valves 51 5th April 2011 01:27 AM
Linear PS help ashley_kitty Power Supplies 2 16th May 2007 12:00 AM
Need help with linear PS tonyptony Power Supplies 33 14th April 2006 09:37 AM
Help with Linear PSU meta Parts 26 19th March 2003 03:56 PM


New To Site? Need Help?

All times are GMT. The time now is 01:33 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2