Weird Farting/Distortion in AMP

#41
Just a thought, does your amp have send/return or pre-amp out and power amp in jacks? If so, plug a patch cord between them and see if it helps. The jacks can get dirty and lose some or all of their internal connection. I had an amp that acted similar and it was dirty jacks. Hope this will help.
 
#42
Ian McLaughlin said:
I would always defer to @Wasnex, but it looks to me like the pickup is awful close to the strings.

Didja try lowering the pup?
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This is the most likely issue, and its common occurrence. The volume/response is non-linear when you get strings close to the pickup. For instance, if you had say 1/4" clearance, you could roughly double the volume by making it 1/8". So that gives you 1/8" as you are playing, and pressing strings, and getting aggressive before you start to spike and overload the signal to your amp. If you START at 1/8" clearance, now it only takes 1/16" depression while playing to double the volume. 1/16" is about .060", less than the guage of the D string alone...yikes!

So, unless you play with a whisper lite touch, you are very likely pushing the strings down to nearly touching the pickup, and that will create spikes in the signal to your amp. Just raise your action or lower the pickups like I do, so you can really dig in, pull the tone, and have a smooth, spike-free signal from your guitar.

PS - that cab and head are tried and true, not finnicky, and robust. Should work properly and easily with about any guitar.
 
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#45
I thought I'd add my 2 cents here. Here's the settings for my LH500 using 2 Hartke Hydrives 1x12's in a 6 piece wicked loud rock band. No distortion but lots of room filling bass. Also, I had distortion on my active bass one time and it was the battery. I replaced it with a new one and there was no change. I then borrowed another battery from my guitar player and it worked perfectly. Try changing with a fresh battery or use a passive bass to check you amps distortion. I no longer like using active basses because the battery could go out on you in the middle of a gig.
lh500.jpg
 
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#49
I wonder if a hi pass filter would solve it. I have a cab that doesn’t handle super lows well... farts out past a certain volume, unless the bass is dialed way back (which wrecks the tone) or a hi pass filter is in place (which preserves it)
 
#51
hogrt123 said:
I have the bass plugged into active. My eq is currently Bass 6.5 Mid 5 Treble 6.5. I do have my bass all the way up. And actually, I just got my battery replaced.
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My first thought was the tube.
There is (i think) one preamp tube in that amp. (12ax7 I think).

That’s where I would start (after batteries and cables). Unplug the amp, don’t touch anything else in there. Pop the old tube out, put a new one in. Shouldn’t cost much at all.

I had a Hartke amp years ago (HA 3500) and the tube preamp channel was making a distortion sound when turned up to a certain volume level and particularly on low notes. A new tube fixed it right up.
 
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#52
wave rider said:
If I’m not mistaken, the LH500 has the Fender tone stack. Bass-Mid-Treble set to 2-10-2 is “flat,” work from that. Your settings are boosting bass and treble but starving your mids, TalkBass orthodoxy is “Mids are your friend”
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True, but just because it’s a fender “style” tonestack, doesn’t mean that 2-10-2 is the right starting place or flat.

You can design a fender tonestack with different values that give different responses. Not all fender style tone stacks are the same. I had a resistor value changed in my old fender for less low bass and more mids. Without putting the amp on a scope, who knows if that amp is a flat fender 2-10-2 amp.

I think probably not.
Larry Hartke has said himself that yes, the amp has a fender tonestack, but it was engineered to sound good with all the knobs at noon.
 
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#53
Pre tubes rarely go bad and when they do it is usually a ringing or huge amount of feedback from the tube going microphonic. Some of those limiter circuits in the past have also caused exactly what you are experiencing. They cause those sounds when the limiter kicks in or out
 
#54
Thanks for all the responses. I think my issue is my setup and how close the strings are to the pickups because I only get this distortion when playing with tons of force or on notes on the E string. I did some tests. I turned up volume but did not play extra hard or try and put extra punch into my sound and everything was find. But as soon as I played with force, the string would touch the pickup and cause the distortion.
 
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#55
Again, proper troubleshooting to identify the actual cause of the symptoms leads to a lot less incorrect guessing.

Start with another bass that's properly set up, and if the problem goes away it's pretty clear that the problem is not the amp, the speakers, the tube, the cables, or especially a "bad cap". ;)
 
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#57
So many great thoughts already on this subject. I'm jumping in becuase I happen to use a LH500 with XL410 and XL210 for my rig.

Jack_RedHouse_HD Museum_2.jpg


Rig:
The whole volume thing has me a bit skeptical. While I do run the extra cab, that's mainly to get speakers closer to my head than just blasting the back of my legs. Step away from your amp and listen from where the audience will be located. The LH500 is a loud amp and I do play in a rock band with 2 guitarists and a whack-em-like-there's-no-tomorrow drummer. I tend to run my volume at...wait for it....1. Not 1 o'clock, just 1. Maybe 1.5 if both guitars are playing with a bunch of distortion for a Metallica or Megadeth tune. For practice my volume is just the amp and cabs. For playing out, the LH500 has a DI so you can send your signal to the PA and still don't need to overdrive the amp. I run my amp EQ flat, and use pre-amps for tone shaping.

Bass:
I couldn't agree more witht the other comments about getting your bass adjusted...action, neck relief and pickup height. Elimnate variables by using a second bass to see if the the issue is the bass, the amp, or the cab.

Final thoughts:
I was using a craptaclar 40-watt Crate house amp in a previous band and it would fart out when I used an active eq bass. Everything was fine if I used a passive bass. Eliminate one variable at a time and you'll find your answer.
 
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#58
Dynomuttasaurus said:
So many great thoughts already on this subject. I'm jumping in becuase I happen to use a LH500 with XL410 and XL210 for my rig.

View attachment 3452028

Rig:
The whole volume thing has me a bit skeptical. While I do run the extra cab, that's mainly to get speakers closer to my head than just blasting the back of my legs. Step away from your amp and listen from where the audience will be located. The LH500 is a loud amp and I do play in a rock band with 2 guitarists and a whack-em-like-there's-no-tomorrow drummer. I tend to run my volume at...wait for it....1. Not 1 o'clock, just 1. Maybe 1.5 if both guitars are playing with a bunch of distortion for a Metallica or Megadeth tune. For practice my volume is just the amp and cabs. For playing out, the LH500 has a DI so you can send your signal to the PA and still don't need to overdrive the amp. I run my amp EQ flat, and use pre-amps for tone shaping.

Bass:
I couldn't agree more witht the other comments about getting your bass adjusted...action, neck relief and pickup height. Elimnate variables by using a second bass to see if the the issue is the bass, the amp, or the cab.

Final thoughts:
I was using a craptaclar 40-watt Crate house amp in a previous band and it would fart out when I used an active eq bass. Everything was fine if I used a passive bass. Eliminate one variable at a time and you'll find your answer.
Click to expand...
Awesome response! My bass has an option to be either active or passive (push pull tone pot). Would you recommend using it in passive. Also whats the volume like on your bass? And what is your eq at (cause I have had many people say different things for this amp are flat)?
 
#59
hogrt123 said:
Awesome response! My bass has an option to be either active or passive (push pull tone pot). Would you recommend using it in passive. Also whats the volume like on your bass? And what is your eq at (cause I have had many people say different things for this amp are flat)?
Click to expand...

Trying the bass in passive could help with the trouble shooting. If the problem goes away when you switch to passive mode it could be the battery or the bass's electronics. However, typically the output in passive mode is a bit lower than active mode, so it may just tell you you need to turn down somewhere in your signal path.
 
#60
hogrt123 said:
Awesome response! My bass has an option to be either active or passive (push pull tone pot). Would you recommend using it in passive. Also whats the volume like on your bass? And what is your eq at (cause I have had many people say different things for this amp are flat)?
Click to expand...

I would try passive mode. What can it hurt?

When I say flat on the LH500 eq, I mean 5 out of 10 on the dials, or 12 o'clock depending on how you refer to it.

Like a lot of people on this forum, I have too many basses. My starting point for any bass is insturnent volume turned all the way up. Tone all the way up for passive instruments, eq knobs at the center point (neither adding nor cutting) for active. The more I play the more I like the intended sound of the bass and think eq is just to season the taste. If an eq needs to be cranked hard one way or the other, there's probably a bigger problem.

With the particular bass in my picture above, I run volume on full, both pickups blended 50/50, and bass eq bumped just slightly, treble eq centered.
 
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