Loud machine gun noise....
Moderators: zaphod_phil, Daviedawg, Graydon, CurtissRobin, colossal
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Loud machine gun noise....
Hello all! I haven't ever worked on this circuit, and here is what one is doing that was brought to be to fix... any idea what this is? Obviously it's the tremolo channel \ circuit, didn't know if anyone had encountered this before... Thanks!
https://youtu.be/A1GFn3OKzfs
https://youtu.be/A1GFn3OKzfs
0 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
NOTE: I already cleaned up the wiring a bit, most is neater and against the chassis now....still same issue.
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: Loud machine gun noise....
Djeez... you've got Woody Woodpecker in there!
Provide us with the schematic and some detailed pics of your build.
Did you already try tube rolling?
Provide us with the schematic and some detailed pics of your build.
Did you already try tube rolling?
1 x
"THIS should be played at high volume..preferably in a residential area"
-
- Superior Amp Tech
- Posts: 750
- Joined: Fri 01/08/10 2:00 am
- Location: Scotland
Re: Loud machine gun noise....
This and related circuits can suffer from tremolo thump. But that seems extreme. Which version is it, i.e. do you have two channels one of which has tremolo? Does it change at all when you move knobs? Is it limited to one or both channels?
As asked already we need to know more about the circuit.
Dd
As asked already we need to know more about the circuit.
Dd
1 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Yes. I have tried different tubes, actually new ones as well with same issue.
0 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Here is what it appears to be, the Mojotone kit basically.
The WD matches what I am seeing. I will have to take pictures and post them, but everything appears to match the attached diagram \ schematic.
The WD matches what I am seeing. I will have to take pictures and post them, but everything appears to match the attached diagram \ schematic.
You do not have the required permissions to view the files attached to this post.
0 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
It does not change with volume\tone. It also appears that the trem channel does not respond to input.Daviedawg wrote: ↑Mon 12/06/21 3:14 amThis and related circuits can suffer from tremolo thump. But that seems extreme. Which version is it, i.e. do you have two channels one of which has tremolo? Does it change at all when you move knobs? Is it limited to one or both channels?
As asked already we need to know more about the circuit.
Dd
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: Loud machine gun noise....
Aaaaahhh.. Mojotone docs!!! They are almost prone to get you in trouble! I really don't like the location of the footswitch jack. Like this the very sensitive wires have to cross/pass the entire output wiring. Mojotone completely ignores the rules of a good grounding scheme. Noisy trem is very often a layout or grounding problem. I wouldn't know where to begin honestly...first of all, very big mistake: the too long hot more to the footswitch jack lies parallel with the heater wiring... no no no!!!jdubzamplification wrote: ↑Mon 12/06/21 8:48 amHere is what it appears to be, the Mojotone kit basically.
The WD matches what I am seeing. I will have to take pictures and post them, but everything appears to match the attached diagram \ schematic.
Take a look in the Downloads section on this site and look for the modern classic 18W.. that's how it should be done in order to achieve a build that's bullit proof
Last edited by Bieworm on Mon 12/06/21 9:30 am, edited 1 time in total.
1 x
"THIS should be played at high volume..preferably in a residential area"
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Yes, I am starting to realize that. I figured it was a grounding issue when I realized that the trem channel is dead to input. Also, I noticed the sweet layout in the layout section. Thank you!Bieworm wrote: ↑Mon 12/06/21 9:23 amAaaaahhh.. Mojotone docs!!! They are almost prone to get you in trouble! I really don't like the location of the footswitch jack. Like this the very sensitive wires have to cross/pass the entire output wiring. Mojotone completely ignores the rules of a good grounding scheme. Noisy trem is very often a layout or grounding problem. I wouldn't know where to begin honestly...jdubzamplification wrote: ↑Mon 12/06/21 8:48 amHere is what it appears to be, the Mojotone kit basically.
The WD matches what I am seeing. I will have to take pictures and post them, but everything appears to match the attached diagram \ schematic.
Take a look in the Downloads section on this site and look for the modern classic 18W.. that's how it should be done in order to achieve a build that's bullit proof
0 x
- JMPGuitars
- Super Duper Admin
- Posts: 3967
- Joined: Tue 09/18/12 8:00 pm
- Location: South Central, MA
- Contact:
Re: Loud machine gun noise....
In the video, the lead dress looks a mess. If you're seeing the mojotone layout, then the ground scheme is probably horrific. Look at the ground scheme thread in my signature, and try to get it to match that. I'd also make sure the amp is correct based on a SCHEMATIC.jdubzamplification wrote: ↑Mon 12/06/21 9:13 amIt does not change with volume\tone. It also appears that the trem channel does not respond to input.
With the amp off, highlighter verify the build with a SCHEMATIC. Start at the input and work your way through. Compare your schematic with one of the verified schematics from our Downloads section.
If there's a footswitch connection, try killing the tremolo with a footswitch. If not, with the amp off, you can carefully ground out the tremolo the same way a footswitch would (see schematics in Downloads section). Once the trem is canceled, see if you get any signal coming through that channel.
Thanks,
Josh
2 x
'I installed a skylight in my apartment yesterday... The people who live above me are furious.' - Steven Wright
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
Modern Ground Schemes
Soldering Technique
B+ Voltage Reduction
Amplifier Tools & Parts Info
Web Design: DolceVittoria.com
Guitars / Amps / Effects: JMPGuitars.com
(anti)Social: Facebook · Instagram
Items for Sale
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: Loud machine gun noise....
.first of all, very big mistake: the too long hot wire to the footswitch jack lies parallel with the heater wiring... no no no!!!
I would move that wiring to the ext speaker jack... and the ground wire should be at the preamp ground
I would move that wiring to the ext speaker jack... and the ground wire should be at the preamp ground
2 x
"THIS should be played at high volume..preferably in a residential area"
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Thanks man! I already addressed most of the wiring, dress issues after the video was taken. I will provide info one day this week once I can look at it again!JMPGuitars wrote: ↑Mon 12/06/21 9:29 amIn the video, the lead dress looks a mess. If you're seeing the mojotone layout, then the ground scheme is probably horrific. Look at the ground scheme thread in my signature, and try to get it to match that. I'd also make sure the amp is correct based on a SCHEMATIC.jdubzamplification wrote: ↑Mon 12/06/21 9:13 amIt does not change with volume\tone. It also appears that the trem channel does not respond to input.
With the amp off, highlighter verify the build with a SCHEMATIC. Start at the input and work your way through. Compare your schematic with one of the verified schematics from our Downloads section.
If there's a footswitch connection, try killing the tremolo with a footswitch. If not, with the amp off, you can carefully ground out the tremolo the same way a footswitch would (see schematics in Downloads section). Once the trem is canceled, see if you get any signal coming through that channel.
Thanks,
Josh
1 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Ok, here is an update. I changed the grounding scheme to match the WD in the downloads section and removed the footswitch jack (for now).
Before, the TREM channel was dead, but now is responsive to input.
The problem still exists, but is now affected by the volume, tone, etc.
This is the strangest thing I have ever encountered....
Any help is appreciated.
Before, the TREM channel was dead, but now is responsive to input.
The problem still exists, but is now affected by the volume, tone, etc.
This is the strangest thing I have ever encountered....
Any help is appreciated.
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: Loud machine gun noise....
Maybe you can post new pics of the amp after the changes you've made?jdubzamplification wrote: ↑Sat 12/18/21 4:56 pmOk, here is an update. I changed the grounding scheme to match the WD in the downloads section and removed the footswitch jack (for now).
Before, the TREM channel was dead, but now is responsive to input.
The problem still exists, but is now affected by the volume, tone, etc.
This is the strangest thing I have ever encountered....
Any help is appreciated.
1 x
"THIS should be played at high volume..preferably in a residential area"
- zaphod_phil
- Builder, Admin
- Posts: 15208
- Joined: Wed 03/19/03 2:00 am
- Location: YYZ
Re: Loud machine gun noise....
A machine gun noise could be from a faulty 12AX7. Those sometimes make various pops and crackles as they get old.
0 x
Nature abhors a clean tube amp
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Swapping tubes makes no difference. I initially thought it was a tube issue honestly.zaphod_phil wrote: ↑Tue 12/21/21 8:09 pmA machine gun noise could be from a faulty 12AX7. Those sometimes make various pops and crackles as they get old.
0 x
- Bieworm
- Verbose Moderator
- Posts: 2305
- Joined: Mon 02/10/20 8:24 am
- Location: Belgium
Re: Loud machine gun noise....
you must be a very patient man... If I had an amp sitting on my bench for 3 weeks straight with a defect, you'd have to tranquilize me or I start breaking stuff!
How can we help you if you don't show us watcha got? A lot of problems were solved by us staring at detailed pics. Have you already tried isolating the problem? Pulling tubes one by one, disconnecting plate wires one by one,...we haven't the faintest idea what you tried thus far, except tube rolling, doing stuff with ground connections,...
How can we help you if you don't show us watcha got? A lot of problems were solved by us staring at detailed pics. Have you already tried isolating the problem? Pulling tubes one by one, disconnecting plate wires one by one,...we haven't the faintest idea what you tried thus far, except tube rolling, doing stuff with ground connections,...
0 x
"THIS should be played at high volume..preferably in a residential area"
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Well, my son's basketball schedule and full time job has hindered me some the past several weeks, along with Christmas shopping and decorating.... so.... lol.Bieworm wrote: ↑Wed 12/22/21 4:49 amyou must be a very patient man... If I had an amp sitting on my bench for 3 weeks straight with a defect, you'd have to tranquilize me or I start breaking stuff!
How can we help you if you don't show us watcha got? A lot of problems were solved by us staring at detailed pics. Have you already tried isolating the problem? Pulling tubes one by one, disconnecting plate wires one by one,...we haven't the faintest idea what you tried thus far, except tube rolling, doing stuff with ground connections,...
Sorry I will get you some pics soon.
Pulling the Tremelo tube (V3 in my case) stops the war (lol). Pulling V2, the noise is still there with but very very faint due to no amplification on that channel.
Thank you for replying, I will get pics as soon as I can.
1 x
-
- Unrated
- Posts: 17
- Joined: Sat 12/04/21 7:26 pm
Re: Loud machine gun noise....
Here are some pics... I started unhooking things to see when the problem stopped....
DISCLAIMER-This is not one of my builds.....
DISCLAIMER-This is not one of my builds.....
You do not have the required permissions to view the files attached to this post.
0 x