Alembic Guitars Club
Alembic products => Owning an Alembic => Troubleshooting => Topic started by: jjbacoomba on August 26, 2024, 05:15:50 PM
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Volume and Bass knobs/pots on my Epic (http://club.alembic.com/index.php?topic=24694.msg246600#msg246600)
« on: April 29, 2019, 05:42:19 PM »
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I am the proud owner of a 1995 Epic 5 string. Bought it brand spankin new. Has been my only bass I have used since then. I am finally getting around to doing something about a problem that I have been having with my Bass and Volume knobs/pots. Its been going on about 4 years and slowly but surely has gotten worse. I notice that when I take my hand off the neck and turn up or down the volume I get a very present scratchy/crackly noise. It doesnt happen if my hand is wrapped around the neck. I cant do volume swells as the volume will cut in and out. As for the bass, somehow it seems that the amount of bass decreases or increases as the night goes on. This does not happen alot, but enough to notice. The other is that when I tap either the bass or volume I can hear it through my cab. It does feel like the volume knob is loose or has a fast ,slippery feel to it. I have opened it up and followed instructions on how to remove the knobs. I cant see anything out of the ordinary( not a luthier, no experience in repairs). I did the turn of the knobs to "clean " them as per the instructions on the website. Still hear that noise. Anyone have this problem. Any suggestions on how to fix it? I am thinking maybe new pots? I did have an unfortunate accident with the treble knob that Mica was able to help me with. Thanks y'all, Joe
Mica, this was goin on before the treble knob incident. Thanks for your help with that. I havent played the Epic for almost a year. I can touch the volume knob and the volume turns off. Not sure what to do other than purchase new volume and bass knobs? Thanks ,Joe
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Sounds like a few issues to me. Any mechanical tapping that comes through the speaker suggests one or both of the pickups is microphonic. You can send them here for testing, but you can probably confirm yourself by tapping the pickups themselves and see if you hear a thumping sound.
I would visually inspect the electronics cavity (you can post images here as well) and make sure that the volume control board can't hit the edge of the cavity, which would cause the signal to short and drop out. The cells that are under the pressure of the nut and washer holding the pots in place will compress over time, which can allow the board inside to travel when you reach the stop.
An early Epic, like yours, would have the first generation of the bass and treble pots that do not have an internal wave washer. This makes the pots have a looser feel and also means you have to use plastic knobs like the original collet knobs you described.
It's hard for me to imagine the circumstances that would make the amount of bass decrease over time now that wouldn't have been present from the get go, I mean, maybe there's a failed or failing cap, but seems unlikely.
If the bass was every stored for a long period of time (like a year) the cleaning procedure might not be effective and the pots would need to be replaced. I know you said you haven't played it in a year, but that was after you had the issue, so while it wouldn't be the cause it may have compounded it.
If the sound you are hearing is like a high frequency sound, there is an RF upgrade chip replacement available, but that doesn't sound like the issue you are having from the description above.
Can you post an image or two of the electronics cavity? Also get back with your test results on the tapping the pickups directly.
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Thanks Mica. Ill get back as soon as I can. :)
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Hi Mica. Am sending a few photos of cavity. I also did two videos. I turned my amp on , turned up the volume, plucked a string and turned up volume on the bass. There was no sound at all. I thought I hooked up the amp wrong so I checked , all was fine. Plucked the string again, no sound then I turned volume on bass off. When I did that there was very noticeable scratching sound and then the sound of the string jumped out. I turned the volume knob repeatedly as instructed for cleaning and there was the loud scratching and volume/sound would shut off and on . I noticed that the knob was loose. When I turned volume knob off and on, back and forth the knob felt like it skipped and made a squeaky kind of noise which would start and stop as I kept turning. I did tap the top of the volume knob and did not notice the tapping come out of the speaker like I did before. I can try to send videos, hopefully you can tell whats going on. Thanks Joe
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tried to send video, but I think the file is too large :(
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I just sent three photos but I dont see them in the thread. Ill try again.
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I just sent three photos but I dont see them in the thread. Ill try again.
tried to send video, but I think the file is too large :(
There's a fairly limited file size to what you can upload here at the Club. You could try a private uplosd to YouTube for the video, and send the link via email.
Photos must be umder 1,000 kB for upload here.
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Take off the backplate while you are turning the volume knob - see if the solder side of the board collides with the cavity wall at the end of the rotation, especially since it feels loose. You don't even need to have the bass plugged in for this visual inspection.
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Joe,
File size for attachments is limited to 1000KB so you may need to "export" the pic as a jpeg and adjust the quality options until it is less than 1MB. And once you attach a file (or up to 10) you won't see it appear in the "preview", it will only appear when you "Post".
Keep trying!
Jimmy J
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You can also email me larger files.
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I clicked on the email thing underneath your picture. I dont see anything to send photo/attachment.
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Thanks Adriann and Jimmy
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My email is mica@alembic.com
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Thanks Mica
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https://youtube.com/shorts/zs-ius9c9Yw
https://youtube.com/shorts/62C2D3g3E8Q
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Hi Mica. Sent photos and links to videos i made. Hope they help. Thanks, Joe
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So it really sounds like the volume pot needs replacing. You can replace the pot or get a new 1-volume harness and just plug it in.
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email sent :)
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Thanks Mica. Whats the difference between the pot and the harness?
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Pretty sure that if you buy just the pot you will have to remove the old pot from the existing harness and solder on the new one. The 1-volume harness would allow you to simply unplug the one with the bad pot, plug in the new one and you are ready to go. Result will be the same. A lot of the Alembic electronics are modular which makes it easy for an owner to fix problems with little to no technical expertise. It also reduces the probability of owners having to ship the electronics to Alembic for repair.
Good to hear you should have your bass up and running again soon!
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Thanks Stephen. I cant seem to wrap my head around harness. Which part is the harness? Sorry, Im not techy at all.
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Found a picture of the volume harness online... the reddish brown connector plugs into your board and the 1-volume harness also has a new 1/4" jack and battery terminal. If the images post properly you will see where the harness plugs in. I have never owned an Epic or bass with the same electronics so yours may be slightly different than the ones in the picture but the concept is the same.
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Thanks Stephen. :)
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Mica, I received the part today. Thanks you so much for your help. I will be trying to install it myself with the help of your instructions. Looks pretty simple. Again, thanks alot. Joe