Question LUKE III preamp: what are the internal trimpots used for?

[Iperfungus]

<div class="bbWrapper">Hi guys!<br /> <br /> Since owning the LIII, I didn&#039;t mess with internal trimpots and I used the preamp/booster with factory settings.<br /> I&#039;ve to say I ignored trimpots until I joined the EBMM family here...ahahah!!! <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /><br /> <br /> Then I started reading here and there...and now I fucking know that those trimpots lie in control cavity and I cannot ignore them anymore.<br /> <br /> Now someone MUST tell me the function of every single trimpot.<br /> There are 5 inside...so I assume they are volume, gain, high, middle, bass controls? <br /> Or something like that...<br /> Or am I totally wrong??<br /> <br /> I didn&#039;t find much information about this around...</div>

 

[ruger9]

<div class="bbWrapper">I think they are in 2 groups? 2 and 3?<br /> <br /> the group of 2 is COMP (compensate) and BOOST (volume boost when depressing volume knob). Compensate adjusts the volume of the in-between positions (2 &amp; 4) so they are the same volume as the standard positions (1,3,5).<br /> <br /> Not sure what the other 3 are, I think I read the same board is used on different guitars, and in the Luke III those 3 pots are not used? I&#039;m sure someone will correct me if I&#039;m wrong. FWIW, my Luke III (2015) only has the 2 pots, not 5.</div>

 

[Iperfungus]

<div class="bbWrapper"><blockquote data-attributes="member: 67752" data-quote="ruger9" data-source="post: 1087059" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087059" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087059">ruger9 said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I think they are in 2 groups? 2 and 3?<br /> <br /> the group of 2 is COMP (compensate) and BOOST (volume boost when depressing volume knob). Compensate adjusts the volume of the in-between positions (2 &amp; 4) so they are the same volume as the standard positions (1,3,5).<br /> <br /> Not sure what the other 3 are, I think I read the same board is used on different guitars, and in the Luke III those 3 pots are not used? I&#039;m sure someone will correct me if I&#039;m wrong. FWIW, my Luke III (2015) only has the 2 pots, not 5. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>Yes, they are in 2 groups...2 and 3.<br /> My Luke III is from 2019.<br /> <br /> I was wondering about the functions of the group of 3, indeed.<br /> I&#039;ve read around that they do change nothing in the Luke III and in MM specs no eq function is mentioned.<br /> Maybe you&#039;re right about same board usage in different guitars/basses.<br /> <br /> The COMP function sounds useful and something to mess not with, then (factory settings should be the best already).<br /> Is that always ON or it&#039;s activated together with booster, with the push-push pot?<br /> So, the only trimpot one could attempt to adjust is booster&#039;s volume. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /></div>

 

[beej]

<div class="bbWrapper">As noted, two of the trimpots are for pickup compensation and boost. Don&#039;t be scared to touch them- you can adjust to taste. (For example, on my HSS Luke I have the comp one turned all the way off.)<br /> <br /> There should two other ones, for the Silent Circuit adjustments (which aren&#039;t relevant if you have an HH). Are you sure you have a 5th? Do you have a pic?</div>

 

[Iperfungus]

<div class="bbWrapper"><blockquote data-attributes="member: 1787" data-quote="beej" data-source="post: 1087061" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087061" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087061">beej said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> As noted, two of the trimpots are for pickup compensation and boost. Don&#039;t be scared to touch them- you can adjust to taste. (For example, on my HSS Luke I have the comp one turned all the way off.)<br /> <br /> There should two other ones, for the Silent Circuit adjustments (which aren&#039;t relevant if you have an HH). Are you sure you have a 5th? Do you have a pic? </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>Yep.<br /> Here we go with some pics: there are 5 trimpots inside! <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /><br /> Mine is HH.<br /> <br /> This could be some Rev. X of the wiring and circuit.<br /> In 2020, when MM swapped pickups from Transitions to MM ones, they also added a PCB and other stuff, if I&#039;m not wrong here.<br /> Wiring should be the same but differently realized.<br /> My LIII is from 2019, maybe they did with some different boards in previous years?<br /> <br /> <a href="https://forums.ernieball.com/attachments/whatsapp-image-2023-11-07-at-00-34-59-jpeg.42760/" target="_blank"><img src="https://forums.ernieball.com/data/attachments/17/17253-995bfe82e32564bb0de1d73e3739da97.jpg?hash=mVv-guMlZL" srcset="" class="bbImage " style="" alt="WhatsApp Image 2023-11-07 at 00.34.59.jpeg" title="WhatsApp Image 2023-11-07 at 00.34.59.jpeg" width="150" height="267" loading="lazy" /></a><br /> <br /> <a href="https://forums.ernieball.com/attachments/whatsapp-image-2023-11-07-at-00-34-45-jpeg.42761/" target="_blank"><img src="https://forums.ernieball.com/data/attachments/17/17254-0a27131158234bc10733501ec513eb46.jpg?hash=CicTEVgjS8" srcset="" class="bbImage " style="" alt="WhatsApp Image 2023-11-07 at 00.34.45.jpeg" title="WhatsApp Image 2023-11-07 at 00.34.45.jpeg" width="150" height="267" loading="lazy" /></a></div>

 

[GoKart Mozart]

<div class="bbWrapper">This has been brought up a few times before; they did switch to a common board at some point but I can&#039;t recall exactly which other model(s) shared that same board. I&#039;ve got a 2013 LIII with the original 2-trimpot board and a 2015 BFR LIII with the 5-trimpot one.</div>

 

[beej]

<div class="bbWrapper">Right- ok it&#039;s that one. The other three are bass/treble/piezo mix.</div>

 

[Iperfungus]

<div class="bbWrapper"><blockquote data-attributes="member: 13951" data-quote="GoKart Mozart" data-source="post: 1087070" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087070" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087070">GoKart Mozart said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> This has been brought up a few times before; they did switch to a common board at some point but I can&#039;t recall exactly which other model(s) shared that same board. I&#039;ve got a 2013 LIII with the original 2-trimpot board and a 2015 BFR LIII with the 5-trimpot one. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>I assume other models would be JP6/7, Luke or Axis Super Sport with piezo, then.<br /> The usage of a common board makes sense, but it&#039;s not that clear how/when trimpots are used and for what they&#039;re used for, since it seems to be not documented.<br /> I found a couple of old threads here with the same questions/doubts.<br /> About the COMP trimpot: is it active on the Luke III HH model as well, to compensate volume in 2 and 4 switch positions with splitted pickups?</div>

 

[Iperfungus]

<div class="bbWrapper"><blockquote data-attributes="member: 1787" data-quote="beej" data-source="post: 1087072" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087072" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087072">beej said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> The other three are bass/treble/piezo mix. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>Not used, then....if there&#039;s no piezo installed.</div>

 

[GoKart Mozart]

<div class="bbWrapper"><blockquote data-attributes="member: 72813" data-quote="Iperfungus" data-source="post: 1087085" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087085" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087085">Iperfungus said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I assume other models would be JP6/7, Luke or Axis Super Sport with piezo, then.<br /> The usage of a common board makes sense, but it&#039;s not that clear how/when trimpots are used and for what they&#039;re used for, since it seems to be not documented.<br /> I found a couple of old threads here with the same questions/doubts.<br /> About the COMP trimpot: is it active on the Luke III HH model as well, to compensate volume in 2 and 4 switch positions with splitted pickups? </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> It must be just the JP6/7/Majesty (piezo + boost) &amp; Valentine (boost) that shares the common board with the LIII; by the time of the PCB switch Music Man had eliminated the piezo option on most models like the ASS, Albert Lee, Luke II; that was also around the time that they pared down the color offerings as well.<br /> <br /> Yes, the compensation pot is active on the HH as well; like you said, it allows you to adjust the volume of the split positions.</div>

 

[Iperfungus]

<div class="bbWrapper"><blockquote data-attributes="member: 13951" data-quote="GoKart Mozart" data-source="post: 1087090" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/goto/post?id=1087090" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-1087090">GoKart Mozart said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> It must be just the JP6/7/Majesty (piezo + boost) &amp; Valentine (boost) that shares the common board with the LIII; by the time of the PCB switch Music Man had eliminated the piezo option on most models like the ASS, Albert Lee, Luke II; that was also around the time that they pared down the color offerings as well.<br /> <br /> Yes, the compensation pot is active on the HH as well; like you said, it allows you to adjust the volume of the split positions. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>This helps to better clarify many things! <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile :)" data-smilie="1"data-shortname=":)" /></div>