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Low gain still easily clipping a Markbass CMD 102P IV

Jonathan Broga

Jonathan Broga

Dec 5, 2021
66
313
Virginia
#1
Just bought this amp and I am really happy with the range of tones it provides. Thought I would find "Old School" useless and ridiculous, however I concurrently switched to flats, and am now old schooling it up all over the place.

I play two active basses through this amp, both 18v. My only issue is that there isn't any sort of Active/Passive input selection, so I have the gain at about 1 to prevent the clipping light from constantly staying lit when digging in with any level of intensity whatsoever. My gut tells me something isn't right with a modern amp requiring such an extreme setting for a modern bass, but on the other hand I keep the input gain barely cracked and I'm still happy enough with the tone, both when clean, and even when I dig in and it does break up.

Anyone have any insight on why Markbass would have such a hot input without any sort of pad?

Another question I have not attained clarity on despite reading multiple threads on the topic. When the clipping light is on I have presumed that is the preamp clipping and I'll be getting some breakup into the power amp. I have not inferred that I am not clipping the power amp and certainly not the speaker either, and that I can light that thing up solid for hours without fear of damaging anything so long as I can stand whatever sound it is making.

Any insight on Markbass gain/am I way off?
 
#2
By any chance is the trim control turned up on your bass's active electronics (if it has one)? Is the pick-up height set according to the bass manufacturer's specifications?

It is an input clip LED, not a power amp clip LED.
 
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#6
I did turn them down at first but didn't really like that since it isn't an easily repeatable action to know exactly where it should be set each time, especially given one of them has just plain black round knobs without a visual indicator of any kind. One is a a J bass and the other a Grainger 4. They both drive the preamp equally hard. They both have the option to run passive so maybe I should give that a shot.
 
#8
Jonathan Broga said:
I did turn them down at first but didn't really like that since it isn't an easily repeatable action to know exactly where it should be set each time, especially given one of them has just plain black round knobs without a visual indicator of any kind. One is a a J bass and the other a Grainger 4. They both drive the preamp equally hard. They both have the option to run passive so maybe I should give that a shot.
Click to expand...
Find the setting on each control that works for you. Then position you finger and thumb on the top and bottom of the control (to start) and turn the control off or full on. Then look at where you finger and thumb are. If that is an awkward hand position, find another finger and thumb position to use as your "off/full on" and "correct setting" index.

Full on or off will always be in the same spots on the control, just use your hand to create an easily recalled index position for where the control works best. It's not a perfect solution, but it may work.
 
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#10
Jonathan Broga said:
Just bought this amp and I am really happy with the range of tones it provides. Thought I would find "Old School" useless and ridiculous, however I concurrently switched to flats, and am now old schooling it up all over the place.

I play two active basses through this amp, both 18v. My only issue is that there isn't any sort of Active/Passive input selection, so I have the gain at about 1 to prevent the clipping light from constantly staying lit when digging in with any level of intensity whatsoever. My gut tells me something isn't right with a modern amp requiring such an extreme setting for a modern bass, but on the other hand I keep the input gain barely cracked and I'm still happy enough with the tone, both when clean, and even when I dig in and it does break up.

Anyone have any insight on why Markbass would have such a hot input without any sort of pad?

Another question I have not attained clarity on despite reading multiple threads on the topic. When the clipping light is on I have presumed that is the preamp clipping and I'll be getting some breakup into the power amp. I have not inferred that I am not clipping the power amp and certainly not the speaker either, and that I can light that thing up solid for hours without fear of damaging anything so long as I can stand whatever sound it is making.

Any insight on Markbass gain/am I way off?
Click to expand...
Have you thought of turning the output down on your basses. I never run my actives at 10, so as not to overdrive anything. Even on the passive setting I keep the output at less than 7, so that I can turn it up should I need to. That's what output knobs are for.
 
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#11
A lot of of people are impressed by a bass with an 18 volt preamp. However, the thing you really need to do in a bass preamp (everything else can be done elsewhere) is buffer the pickup's output, so the signal will survive the trip through a cable (actually, you don't really need to do even that, but I digress). To do a good buffer for a bass pickup, you don't need anywhere near 18 volts of supply, which tempts the preamp maker to give the thing more output, to impress the person buying the bass (It's so HOT!!!). Unfortunately, this often results in this situation - you have an amp, or pedalboard where everything runs off of 9 volt supplies, so you can't open the volume control on the bass without clipping the next thing in the chain.

I designed pro audio gear for over 40 years - microphones being a big part of what we made. Our Marketing folks would often get obsessed by the idea of making our products "hotter" - if you A/B two products by plugging them into the same PA, and don't adjust the gain, the hotter one sounds better, so hotter is often seen as better. But, it isn't - hotter just means the system doesn't have as much headroom, so you can't mic a loud thing without clipping. Here, the situation is the same - the person who designed the preamp in your bass didn't really care about whether or not the thing worked better in a real world use case, they just made it hotter for no good reason.

At one point in my career, I wrote a "manifesto" detailing how hot we should make our mics - setting a limit as to the sensitivity, so our users didn't end up in this situation. I set limits for speech mics, vocal (singing) mics, and instrument mics. It was a contentious thing, but it helped us get most of our products into a reasonable sensitivity range. This was prompted by a series of mics that we made that was too hot, and that had elicited a lot of negative feedback from the field. There was one product that my company put out after I published my manifesto (over my objections) that was hotter than what I suggested, and it didn't do well at all in the field.

Products that aren't designed with the real world in which they are going to be used in mind are stupid. There is no real need for an 18 volt preamp in a bass guitar, and if the preamp is designed to "take advantage" of the increased voltage space, this situation is what you're gonna get much of the time.

Ask the manufacturer of your bass if there is a gain trim control in your preamp. If there is, at least the designer had some clue that this might be necessary, so I give that person some credit, but of course, if the thing needs to be turned down to not clip the next thing in the chain, it's just more proof that the thing doesn't need 18 volts (and two batteries).
 
Last edited:
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#12
micguy said:
A lot of of people are impressed by a bass with an 18 volt preamp. However, the thing you really need to do in a bass preamp (everything else can be done elsewhere) is buffer the pickup's output, so the signal will survive the trip through a cable (actually, you don't really need to do even that, but I digress). To do a good buffer for a bass pickup, you don't need anywhere near 18 volts of supply, which tempts the preamp maker to give the thing more output, to impress the person buying the bass (It's so HOT!!!). Unfortunately, this often results in this situation - you have an amp, or pedalboard where everything runs off of 9 volt supplies, so you can't open the volume control on the bass without clipping the next thing in the chain.

I designed pro audio gear for over 40 years - microphones being a big part of what we made. Our Marketing folks would often get obsessed by the idea of making our products "hotter" - if you A/B two products by plugging them into the same PA, and don't adjust the gain, the hotter one sounds better, so hotter is often seen as better. But, it isn't - hotter just means the system doesn't have as much headroom, so you can't mic a loud thing without clipping. Here, the situation is the same - the person who designed the preamp in your bass didn't really care about whether or not the thing worked better in a real world use case, they just made it hotter for no good reason.

At one point in my career, I wrote a "manifesto" detailing how hot we should make our mics - setting a limit as to the sensitivity, so our users didn't end up in this situation. I set limits for speech mics, vocal (singing) mics, and instrument mics. It was a contentious thing, but it helped us get most of our products into a reasonable sensitivity range. This was prompted by a series of mics that we made that was too hot, and that had elicited a lot of negative feedback from the field. There was one product that my company put out after I published my manifesto (over my objections) that was hotter than what I suggested, and it didn't do well at all in the field.

Products that aren't designed with the real world in which they are going to be used in mind are stupid. There is no real need for an 18 volt preamp in a bass guitar, and if the preamp is designed to "take advantage" of the increased voltage space, this situation is what you're gonna get much of the time.

Ask the manufacturer of your bass if there is a gain trim control in your preamp. If there is, at least the designer had some clue that this might be necessary, so I give that person some credit, but of course, if the thing needs to be turned down to not clip the next thing in the chain, it's just more proof that the thing doesn't need 18 volts (and two batteries).
Click to expand...
Funny, both my basses run at 18V and neither have ever caused clipping. I have never used the padded input on any amp and my current amp I have the high gain switch on.
 
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#13
Al Kraft said:
Find the setting on each control that works for you. Then position you finger and thumb on the top and bottom of the control (to start) and turn the control off or full on. Then look at where you finger and thumb are. If that is an awkward hand position, find another finger and thumb position to use as your "off/full on" and "correct setting" index.

Full on or off will always be in the same spots on the control, just use your hand to create an easily recalled index position for where the control works best. It's not a perfect solution, but it may work.
Click to expand...

That's good, practical advice. I may start doing this myself!

And yes, to parrot previous statements...the volume knob being turned down on an active bass will not result in any tone/change loss unlike passive electronics.
 
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#14
Thumpin6string said:
Funny, both my basses run at 18V and neither have ever caused clipping. I have never used the padded input on any amp and my current amp I have the high gain switch on.
Click to expand...

That most likely means that the preamp designer resisted the urge to add more gain, which is good. Then again, the fact that they have never caused clipping most likely means they really don't need 18 volt supplies - you have headroom (and an extra battery) you don't need. It's a design which works, but it's a bit sub-optimal.
 
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#15
micguy said:
That most likely means that the preamp designer resisted the urge to add more gain, which is good. Then again, the fact that they have never caused clipping most likely means they really don't need 18 volt supplies - you have headroom (and an extra battery) you don't need. It's a design which works, but it's a bit sub-optimal.
Click to expand...
I went from 9V to 18V and it improved the tone quite a bit.
 

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