Huge difference in tone between post-EQ feed to PA vs amp tone.

[caballero59]

My amp is the CMD112p and when I feed a post-eq line out to the PA, the sub rumbles unacceptably. My thought is the 12" cab is simply not reproducing those frequencies so the PA feed and bass amp sound totally different. It appears the Markbass combo does not have a HPF.

 

[Jazzdogg]

Send a pre-EQ DI signal to FOH.

 

[CatOnTheBass]

The obvious solution (on your end) would be to engage the "Pre EQ" button on the Markbass (that's literally what it's there for) or to use a separate DI box.

My follow up question would be, where is the sound guy in all of this? Why isn't the sound guy EQ'ing the boomy frequencies?

 

[Passinwind]

My amp is the CMD112p and when I feed a post-eq line out to the PA, the sub rumbles unacceptably. My thought is the 12" cab is simply not reproducing those frequencies so the PA feed and bass amp sound totally different. It appears the Markbass combo does not have a HPF.

Or maybe the HPF is right in front of the power amp but comes after the post-EQ line feed. My own DIY amps are like that.

 

[Wasnex]

My amp is the CMD112p and when I feed a post-eq line out to the PA, the sub rumbles unacceptably. My thought is the 12" cab is simply not reproducing those frequencies so the PA feed and bass amp sound totally different. It appears the Markbass combo does not have a HPF.

Your theory is correct.

Ideally your sound needs to be processed separately for different locations and uses. The acoustics on stage are likely to be different than out in the house. Also, the type of sound you need to hear for effective monitoring may be a bit different than what works well in the FOH mix.

Unless your cab is full-range and flat-response (FRFR), the sound coming from a Post EQ DI is not very representative of what you hear on stage. Even if your cab is relatively FRFR, it probably will not sound exactly like the PA cabs. So using Post EQ is not really an effective way to deliver the tone profile you envision to the audience.

Most audio techs prefer a Pre EQ DI. Pre gives the audio tech a more neutral starting point, so they don't have to reverse engineer and potentially undue any of the processing you are applying. Pre EQ tends to be way easier for the audio tech to work with. It's sort of like starting with a "blank canvas." If the audio tech understands your tone goals, it's usually fairly easy to massage a Pre EQ DI into the desired ballpark. It's unreasonable to expect the audio tech to capture your tone goals perfect, but they should be able to get fairly close.

An example where Post EQ is preferred is when your amp is actually a significant source of mojo. For example if you have a tube preamp that is pushed in drive territory, it is essential that the DI be taken after the distortion is generated. I generally prefer mic'ing the cab over a Post EQ DI...but many audio techs are reluctant to use a mic on bass as well. If you have a valid reason to use Post DI or a mic, I suggest contacting the audio tech before gig day to discuss your tone concept and try and work things out.

This is not something you should generally work out during setup/sound check because the audio tech will typically be preoccupied with keeping track of and resolving a myriad of little details and emergent problems. So the audio tech may not be able to give you the personal attention you want.

 

[scott sinner]

This is why many use a DI with an amp/cab sim built in. Depends on your amp of course. Some bass amps indeed are very full range flat response. But Ive never thought of Markbass as being one.

 

[caballero59]

Your theory is correct.

Ideally your sound needs to be processed separately for different locations and uses. The acoustics on stage are likely to be different than out in the house. Also, the type of sound you need to hear for effective monitoring may be a bit different than what works well in the FOH mix.

Unless your cab is full-range and flat-response (FRFR), the sound coming from a Post EQ DI is not very representative of what you hear on stage. Even if your cab is relatively FRFR, it probably will not sound exactly like the PA cabs. So using Post EQ is not really an effective way to deliver the tone profile you envision to the audience.

Most audio techs prefer a Pre EQ DI. Pre gives the audio tech a more neutral starting point, so they don't have to reverse engineer and potentially undue any of the processing you are applying. Pre EQ tends to be way easier for the audio tech to work with. It's sort of like starting with a "blank canvas." If the audio tech understands your tone goals, it's usually fairly easy to massage a Pre EQ DI into the desired ballpark. It's unreasonable to expect the audio tech to capture your tone goals perfect, but they should be able to get fairly close.

An example where Post EQ is preferred is when your amp is actually a significant source of mojo. For example if you have a tube preamp that is pushed in drive territory, it is essential that the DI be taken after the distortion is generated. I generally prefer mic'ing the cab over a Post EQ DI...but many audio techs are reluctant to use a mic on bass as well. If you have a valid reason to use Post DI or a mic, I suggest contacting the audio tech before gig day to discuss your tone concept and try and work things out.

This is not something you should generally work out during setup/sound check because the audio tech will typically be preoccupied with keeping track of and resolving a myriad of little details and emergent problems. So the audio tech may not be able to give you the personal attention you want.

Super good info in this response. Thank you.

Furthermore, at risk of overthinking this, this anomaly has me perplexed. It is usually recommended to let the PA do the heavy lifting, but since much of the bass lives above 100Hz where many subs are crossed at, isn't there major phase cancelation in the mid bass coming from the PA tops typically separated on each side of the stage?

 

[Wasnex]

Super good info in this response. Thank you.

Furthermore, at risk of overthinking this, this anomaly has me perplexed. It is usually recommended to let the PA do the heavy lifting, but since much of the bass lives above 100Hz where many subs are crossed at, isn't there major phase cancelation in the mid bass coming from the PA tops typically separated on each side of the stage?

Running the bass through the PA is often an improvement, but it does not resolve all problems. IMHO live sound is more about trying to achieve a reasonable compromise, rather than perfection.

 

[dbsfgyd1]

Your theory is correct.

Ideally your sound needs to be processed separately for different locations and uses. The acoustics on stage are likely to be different than out in the house. Also, the type of sound you need to hear for effective monitoring may be a bit different than what works well in the FOH mix.

Unless your cab is full-range and flat-response (FRFR), the sound coming from a Post EQ DI is not very representative of what you hear on stage. Even if your cab is relatively FRFR, it probably will not sound exactly like the PA cabs. So using Post EQ is not really an effective way to deliver the tone profile you envision to the audience.

Most audio techs prefer a Pre EQ DI. Pre gives the audio tech a more neutral starting point, so they don't have to reverse engineer and potentially undue any of the processing you are applying. Pre EQ tends to be way easier for the audio tech to work with. It's sort of like starting with a "blank canvas." If the audio tech understands your tone goals, it's usually fairly easy to massage a Pre EQ DI into the desired ballpark. It's unreasonable to expect the audio tech to capture your tone goals perfect, but they should be able to get fairly close.


An example where Post EQ is preferred is when your amp is actually a significant source of mojo. For example if you have a tube preamp that is pushed in drive territory, it is essential that the DI be taken after the distortion is generated. I generally prefer mic'ing the cab over a Post EQ DI...but many audio techs are reluctant to use a mic on bass as well. If you have a valid reason to use Post DI or a mic, I suggest contacting the audio tech before gig day to discuss your tone concept and try and work things out.

This is not something you should generally work out during setup/sound check because the audio tech will typically be preoccupied with keeping track of and resolving a myriad of little details and emergent problems. So the audio tech may not be able to give you the personal attention you want.

Amen. Sound Techs are not mind readers. Communication is key. Be respectful of their time, and always treat them with respect.

 

[Drredplate]

You could close mic the cab. I think close mic sounds better imo

 

[trevcda]

You didn't mention if the PA was yours or just PA's you run into in the field, but most if not all digital mixing boards have a high pass filter on each channel. However, starting with a pre-EQ DI is the right move. From there insuring that the main EQ is not all jacked up in attempt to make the kick drum sound good is what I would look for next.

 

[JeezyMcNuggles]

My amp is the CMD112p and when I feed a post-eq line out to the PA, the sub rumbles unacceptably. My thought is the 12" cab is simply not reproducing those frequencies so the PA feed and bass amp sound totally different. It appears the Markbass combo does not have a HPF.

Yes, your single 12" speaker does not produce those frequencies at a noticeable level.

Plus, your channel in the mixer might have the bass boosted as well.

 

[JeezyMcNuggles]

Super good info in this response. Thank you.

Furthermore, at risk of overthinking this, this anomaly has me perplexed. It is usually recommended to let the PA do the heavy lifting, but since much of the bass lives above 100Hz where many subs are crossed at, isn't there major phase cancelation in the mid bass coming from the PA tops typically separated on each side of the stage?

Our PA makes my E and F notes pretty much disappear in our practice spot. Live though, I haven't noticed anything wrong. I chaulk it up to room, placement, etc.

 

[GreyBeard]

Throw a mic on it.

 

[MDBass]

Send a pre-EQ DI signal to FOH.

That will do nothing to solve this particular issue.

The DI is sending too much sub frequency info that his cab isn’t producing, and it will is pre-EQ mode as well unless he’s boosting a ton of bass on his amp.

 

[MDBass]

My amp is the CMD112p and when I feed a post-eq line out to the PA, the sub rumbles unacceptably. My thought is the 12" cab is simply not reproducing those frequencies so the PA feed and bass amp sound totally different. It appears the Markbass combo does not have a HPF.

Whoever is running your FOH needs to apply an HPF on your channel: every mixer will have them on every channel, even most ancient analog units.

If you’re boosting a lot of bass on your amp and running a post-EQ signal that may also be causing a problem, but if you aren’t an HPF on your channel will solve the problem almost instantly.

Should take less than 30 seconds even with a variable HPF on a digital board.

 

[sawzalot]

Usually the FOH engineer will engage a HPF on the bass channel. Super easy fix.

 

[GreyBeard]

It is really up to the FOH engineer to EQ your bass so that it fits in a pocket. A lot of them these days just crank it up until they feel some rumble and have a good light. If you can do it, go back to the board and play while making some suggestion to the sound tech.

 

[caballero59]

Whoever is running your FOH needs to apply an HPF on your channel: every mixer will have them on every channel, even most ancient analog units.

If you’re boosting a lot of bass on your amp and running a post-EQ signal that may also be causing a problem, but if you aren’t an HPF on your channel will solve the problem almost instantly.

Should take less than 30 seconds even with a variable HPF on a digital board.

My analog mixer has a 100hz HPF on each channel (probably 12 dB/octave) but this isn't enough. I've been taking a look at the Thumpinator. It looks like a solution. I also have some excellent filtering and compression available on the second input of a Fractal FM3.

 

[caballero59]

That will do nothing to solve this particular issue.

The DI is sending too much sub frequency info that his cab isn’t producing, and it will is pre-EQ mode as well unless he’s boosting a ton of bass on his amp.

That's it exactly.