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Amplification Issues

J

jimmeyer176

Guest
Oct 2, 2012
80
5
#1
Heya...I'm an experienced bass player but have never really gotten into the 'tech' part of gear, I never cared to understand it, probably because I didn't need to, but have not run into a small issue.

I currently play a GK MB500 (500 watts @ 4ohms) solid state amp, through a single GK NEO 2x12 (8ohm) cabinet. I use an Ibanez Soundgear with active pickups.

What I find is that the amp CLIPS when the gain is about 40-45% up, or 11:30. From there, it seems like the amp doesn't get any louder, regardless of how much the master volume is turned up. My thinking is that I need more gain, in order to get more volume.

However, if the amp is clipping, I can't achieve more gain...therefore I would need to get another cabinet in order to achieve more volume...right?

I'm thinking about pairing it with an identical NEO 2x12 on top, or the NEO 1x15, I'm leaning towards the 2x12 as I'm thinking 2x12 speakers will move more air than a single 15 - correct?

So...why is the amp clipping at what I think is a fairly moderate volume? Is the speaker receiving too much power and sending some back (needing another cab), or am I over driving the amp? If I'm overdriving the amp why does a 500 watt amp CLIP when the gain is less than 50% capacity?

Finally...does impediance have any effect on clipping? Would the gain be able to be pushed more on say a 4ohm cabinet? And would 2 cabs allow the gain to be pushed more?

Thanks!
 
#2
The gain knob controls the volume of your instrument going into the amp---not the volume of the amp going out to the speaker. The two are related of course, turn up the volume of the instrument and it will get some louder at the speaker; but as you observed, that only works up to the point where the amp starts clipping. Because that's what's clipping: the input stage of the amp.

Stacking a second 8 ohm 212 on top of the first one is the very best possible solution. It will work fantastically for getting more undistorted loudness from your amp. Other solutions may work to some extent, but you already hit the nail on the head with the second 212 idea.
 
#3
Whoa, there. First of all, I have the exact same amp head and the exact same cab as you do: MB500 and Neo 212. (I also have an MBX 410, but let's leave that for a minute.)

First of all, you should be running your Master at 3 o'clock. Then nudge your Gain knob up as needed.

You have an 8 ohm 212 cab, so your amp is pushing no more than 350w--which is plenty for that cab. It surely can't take more. If you need more volume, get a second 212. Then your amp will be unleashing up to 500w--but more importantly you'll have doubled your speakers.

Now, about clipping. You're probably talking about the clip light on the front. If it's lighting up, you might want to push the button in. You're sending too hot a signal, possibly from those active pickups. Push in the -10db button and it should go away.
 
#4
def go for a second cab. right now you basically have like a 250 watt amp. the rec's on here would be to keep it the same as the cab you've got. as far as gain goes, some stuff stops increasing the volume and just goes into overdriven tones, by design. do you use a lo-gain input, or click on a pad? this may help with the clipping, too. from me asking the same q about the clip light, it's not a huge problem unless it just stays on with all signal. blinking or even coming on often arent worrysome issues. if it is just plain lit with anything you put into it, then there is something you need to change. adding more gain (or a boost/eq pedal) before the amp will only make it worse. sounds to me like the solution here is the second cab.


^^^they type faster than i do;)
 
#5
Your active bass is overdriving your preamp. You're right about not getting any louder by turning up the output, but cabs don't "send power back", that would be like your eyes refusing to be blinded by the sun.

You are dead right about getting another identical 2x12. You will like that for sure. It will make your sound so much bigger you will have to turn down.
 
#12
scottfeldstein said:
You guys, I seriously think the problem is that his signal is too hot going into the amp. I don't think it has anything to do with how many speakers he has.

Push in the -10db button. Make sure you're not using any pedals that are radically changing your level before going into the amp.
Click to expand...

Maybe, but also consider he said this:

jimmeyer176 said:
What I find is that the amp CLIPS when the gain is about 40-45% up, or 11:30. From there, it seems like the amp doesn't get any louder, regardless of how much the master volume is turned up. My thinking is that I need more gain, in order to get more volume.
Click to expand...

If it was ONLY overloading the front end, he should still get more volume from the master. Yes, it will still sound like crap, but it should be able to be made louder crap.

Sounds to me like two problems...........

Clipping the front end (either by bass being too hot, or user error in setting gain structure).

AND.....hitting the limits of his cab. He keeps turning up. but does not get any louder.
 
#14
Agree with Scott. -10db button should be pushed in for a strong signal from bass.
A second 2x12 should push more air than the 1x15. For the OPs comfort, the 2x12 also has a thermal limit of 600 watts whereas the 1x15 would be only 400 watts. Better case to match the 2x12 with another 2x12 to increase volume if still required.
I believe the 2x12's can be sold as either 4 or 8 ohms. You'll want to ensure your original 2x12 isn't 4 ohms otherwise a second cab can't be bought to use with that amp.
 
#19
OK...so if I'm reading people correctly, I need to:
- engage the -10db button
- turn the master to 3 o'clock, and bring gain up accordingly for volume (this is what the owners manual says) until it starts clipping, then back off a hair
- if not enough volume, get another identical cabinet

Sound about right?
 
#20
So just to verify, volume comes from 3 things...
1. Power, watts - how much power you have available from your head
2. Maximizing ohms, using a 4ohm cab or two 8 ohm cabs
3. Size and number of speakers

---and---

The reason why people are suggesting getting another identical 2x12 cab is because:
- I will have four, 12 inch speakers pushing air
- I will have 2 cabinets able to push 600 watts each
- I will be able to push the entire 500 watts with two, 8 ohm cabinets
- identical cab will be the most efficient overall

Do I have it right?
 

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