I just today bought myself a bassman 10 4x10. At low volume levels it sounds clear and fine, but turned up to band levels the low notes elicit a crackle that lasts as long as the note rings. Based on that i thought something was loose and the vibrations from the speakers were causing the crackle. I unplugged the internal speakers and ran it through a separate cab with the same results. It doesn't really hiss anymore than any other amp I've used, and it doesn't pop unless the cable from my pedals to my amp gets moved in a rough way...which again happens with any amp I've used.
I haven't poked around in it too much because my equipment wasn't handy but it seems to be modified quite a bit. It appears to have both a tube and solid state rectifiers. I didn't notice if the diodes were still connected but they are still in the chassis, but the tube glows and is fully connected in the circuit. Not sure what else has been changed since I'm not sure what circuit it is, but based on the rectifier I'd bet other things had been changed.
It isn't the tubes as I replaced all of them (minus the rectifier because I don't have one and I have no idea what kind it is) with known working tubes. I'm leaning towards cold bias, bad soldering joints, or maybe the wires. It's quite a rats nest in there with a mix of cloth and pvc covered wires.
Just more or less wondering where to start first in this journey. Any ideas would be quite appreciated. Thanks
Bassman 10 Crackling Issues
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absolutelyfibulous
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- Location: north dakota
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Stevem
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- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Bassman 10 Crackling Issues
Well if it has a 5 volt recto in there, then the PT has been changed out, or there is aadded 5 volt filament PT.
The popping noise could be a bad solder joint from all the mod work, or the OT is arcing over when the amp is driven hard and the voltage swing across it gets to a certain level, or the recto socket could be arcing.
Be sure to check the solder connections in the filter dog house and if the filters are bleeding.
If the PT was changed out check any winding center tap grounds.
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Any of the high current drawing sections of the amp like the output stage and or the power supply are the most likly places for this issue.
The popping noise could be a bad solder joint from all the mod work, or the OT is arcing over when the amp is driven hard and the voltage swing across it gets to a certain level, or the recto socket could be arcing.
Be sure to check the solder connections in the filter dog house and if the filters are bleeding.
If the PT was changed out check any winding center tap grounds.
\
Any of the high current drawing sections of the amp like the output stage and or the power supply are the most likly places for this issue.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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absolutelyfibulous
- Posts: 2
- Joined: Tue Sep 17, 2013 2:13 pm
- Location: north dakota
Re: Bassman 10 Crackling Issues
I will definitely check that out. I appreciate it!
Re: Bassman 10 Crackling Issues
The above issue of noise is gone.
John (absolutelyfibulous) and myself have been having fun working on this Bassman 10. Had to increase the slope resister to 150k to get some treble and mid range out of this amp. Yes I changed the tone caps.
Added presence pot 5k/.1uf/47k for now. Already had a hole in the chassis so drilling that out was easy.
Removed ground switch and cap and rewired the fuse holder correctly on line side instead of neutral side.
Added bias probe jacks on back and 10k bias pot in the old ground switch hole on back.
Going to try EL34's and KT66's as well as speaker changes whatever John decides.
I can see another triode being added too.
John (absolutelyfibulous) and myself have been having fun working on this Bassman 10. Had to increase the slope resister to 150k to get some treble and mid range out of this amp. Yes I changed the tone caps.
Added presence pot 5k/.1uf/47k for now. Already had a hole in the chassis so drilling that out was easy.
Removed ground switch and cap and rewired the fuse holder correctly on line side instead of neutral side.
Added bias probe jacks on back and 10k bias pot in the old ground switch hole on back.
Going to try EL34's and KT66's as well as speaker changes whatever John decides.
I can see another triode being added too.
Last edited by M Fowler on Fri Apr 11, 2014 10:08 pm, edited 1 time in total.
Re: Bassman 10 Crackling Issues
Maybe increase the 10k mid pot to 50k might get some mids.
220pf treble cap, 150k slope, .022uf, .047uf on tone stack right now.
250kL treble pot stock, 250kL bass pot stock and 10kL mid pot stock.
I thinking bluesmaster here change over to 250kL treble pot, 250kA mid pot, and 500kA bass pot.
220pf treble cap, 150k slope, .022uf, .047uf on tone stack right now.
250kL treble pot stock, 250kL bass pot stock and 10kL mid pot stock.
I thinking bluesmaster here change over to 250kL treble pot, 250kA mid pot, and 500kA bass pot.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: Bassman 10 Crackling Issues
Your gonna rewire the output sockets for the ELs I hope?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: Bassman 10 Crackling Issues
Yes already been done and added rear panel bias meter jacks.Stevem wrote:Your gonna rewire the output sockets for the ELs I hope?