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LMIII Problem/Cab recommendation?

shrigg

shrigg

Joy Decision Bassist/BL, AudioKinesis Beta Tester
Supporting Member
Sep 7, 2007
2,966
1,398
Traverse City, MI
#1
My new Little Mark III sounds GREAT but when I play hard (specifically popping) the amp kills all output, like it's kicking into protection mode. It will do it every time I play hard, even if the gain is set quite low. Once it does this I have to power the amp down and back up to get any sound again.

To check the LMIII power section specifically, I dragged out a power amp and ran the line out into it. Voila, problem solved. Now it plays at all attack volumes. However I noticed on hard attacks the clip lights of the power amp would come on and the output would distort, sounding quite nasty. My basses are hot but not THAT hot... Just a Music Man SUB 5 (active) and a G&L L-1000 (passive)

I know my 4 ohm Acme B2 is a power hungry cab but this amp is unusable if I can't slap and pop hard without it shutting down. Or is my playing style out of line?

Should I send the Little Mark back? I'll try A/Bing it against an Eden WTX500 into my B2 to see how the Eden compares headroomwise. Also I'll try the LMIII into an Eden 210 and see if it still shuts down.

I have a feeling I may be exercising the Musician's Friend return policy.... Too bad because I love the LMIII, guess I could just get a replacement that WORKS

Here is the test scene:
DSC_0087.jpg
 
#4
Sounds like something wrong with it. My LMII never does stuff like that, even when I crank the gain really hot and make it clip. I would take advantage of the return period and return it and get another one.
 
#6
One observation: The LMIII sounds MUCH better with its own power amp than the Line Out into my Crown XTi-1000. Warmer and more organic. The Crown power amp managed to make the LMIII sound almost harsh and sterile, or at least more than I'd ever heard a Markbass sound. A big part of the Markbass magic is in that power section!
 
#8
shrigg said:
One observation: The LMIII sounds MUCH better with its own power amp than the Line Out into my Crown XTi-1000. Warmer and more organic. The Crown power amp managed to make the LMIII sound almost harsh and sterile, or at least more than I'd ever heard a Markbass sound. A big part of the Markbass magic is in that power section!
Click to expand...
Try using the DI out... post eq.
 
#10
::::BASSIST:::: said:
Try using the DI out... post eq.
Click to expand...

Check. That's what I was doing.

::::BASSIST:::: said:
Something sounds wrong here. If your having problems with your poweramp like this (I assume its around 1000w?) than it might be the combination of your playing style and your bass.
Click to expand...

The power amp is a Crown XTi1000, bridged for 1400w into 4 ohms.

I have a few questions in my mind, maybe my B2 cab has an issue internally in the crossover that makes the amp shut down when hit with lots of power.

Also I think my playing style needs to be more level. I can't expect to pop as HARD as I can in a live setting and expect consistent sound. But I am very surprised to see the amp shutting down consistently, seems wrong. It even does it when I use a Keeley compressor into it. My basses aren't that hot!
 
#12
I would check my speaker cable with a meter or try another. I do not think that is your problem though.

The Acme Cab has an increased amount of low end available unlike most cabs on the market. I think the cab is capable of lower ohms at lower registers (than most) and this is causing the LMIII protection circuitry to kick in seeing a resistance that is lower than it can perform at. Others can perhaps elaborate on this with more knowledge than I have.

This is further complicated with your aggressive playing style. The input on the LMIII is extremely sensitive and can be pushed into clipping (causing further trouble on down the line) quite easily. The distortion you hear is causing the power amp to push hard into a cab that will take it and be starving for more.

The input sensitivity combined with the Acme cab is a recipe for a Protection Circuit engaging.


But perhaps you'll find that it is entirely something else.
 
#15
shrigg said:
Here is my cable... brand new. Maybe the B2 is just too much for the LM?
Next I'll try a Speakon...

DSC_0090.jpg
Click to expand...

It's worth a try. I did get a brand new speaker cable once that was bad.

Like I said for an aggressive player the input sensitivity on the LMIII is too hot.

I am an aggressive player as well and I have to set the input volume on my LMIII at the first dot and still clip it occasionally with all my Passive Basses. I also have a MarkBass TA-501 which is a similar amp but the input sensitivity is waaaay different. On the TA-501 I set the input level at 12:00 and have no problem with clipping, with my LMIII I barely have the input level on and still clip it. Strange.:eyebrow:

I do not have the amp shutting down problem you are having though I'm using different cabs.


Nighttrain1127 said:
Could be your pickups are too close to the strings try lowering them a bit and see if that helps. It may not be the amp at all.
Click to expand...

As far as string height it may help with the input level a small amount but if my string height were shutting an amp down I would think the world was coming to an end.
 
#17
Red Planet said:
...the input sensitivity on the LMIII is too hot.

I am an aggressive player as well and I have to set the input volume on my LMIII at the first dot and still clip it occasionally with all my Passive Basses. I also have a MarkBass TA-501 which is a similar amp but the input sensitivity is waaaay different. On the TA-501 I set the input level at 12:00 and have no problem with clipping, with my LMIII I barely have the input level on and still clip it. Strange.:eyebrow:
Click to expand...

Ah ha! Well I feel pretty dumb right now because I was using "blink the clip light when playing my hardest" method of setting the gain which put it at around 12:00 or close to it. I have backed way off to 9:00 or so and now the amp doesn't shut down when beaten the same way. Edit: With gain at first dot, I can get it to shut off OCCASIONALLY popping brutally hard up the neck on the active SUB5. Really shouldn't play that way anyhow.....

I'm a little nervous about the Master being past 12:00 with still not a tremendous amount of volume. Guess that is my B2 doing its innefficiency thing.... Hearing your setting of the first dot makes me wonder if you get much output from your LMIII?

DSC_0091.jpg
 
#18
I turn it any louder and start clipping so you tell me. It's pretty darn loud though. Not as close to running a QSC PLX2 1804. That is loud.

I would say the TA-501 is a bit louder than the LMIII but I attribute that to having a compressor which allows the signal to be smoothed out somewhat.

The TA-501 AT 12:00 and the LMIII at the first dot seem to be at the same amount of dbs in Gain. So I do not think there is a problem. Perhaps you need a compressor?

If I remotely thought there might be a problem with the head I'd at least send it back to get another. I suspect the Acme is not well suited to the Micro Heads, given that dip in impedence possible way down causing an amp to have to work hard. Plus the acme is hardly lightweight so why use a Micro head with a heavy weight cab?
 
#19
Also I accidently plugged my LMIII into 2.67 ohm load once when I first got it by mistake and the amp shut off after about 3 notes. So I guess this is normal when it sees to low a resistence.
 
#20
I agree on the need for a compressor. I am waiting patiently for a LM compressore. MF doesn't have em till 12-31 :( Till then I'm making do with my Keeley but it's not great for bass (rolls off the low end)

As far as speaker choice, I was considering a Wizzy 10 but I'm not sure how it would handle my playing style. Opinions?
 

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