Why am I struggling to make bass sound good through PA?

[mrtcat]

We have a great PA (rcf 932a x2 and rcf 905 sub x2) and a capable mixer (XR18) and yet im never happy with the bass sound through PA. 

 

I have a Darkglass Anagram which sounds amazing for recording direct into a PC and awesome on the multi track live recording we take direct from the desk at gigs. It also sounds perfect in my iem mix. My amp is a Darkglasd M900 and my cab is a greenboy F112. That setup sounds killer too.

 

Why is it then that the bass sound coming out of the PA just always seems to sound a bit woolly and soft and lacking those lovely clean piano type lows. Even if I turn all processing off on the desk it seems to sound like it lacks the clean weight of sound and crisp top end. Do I just need to be braver with the eq or is it something in the PA speakers that hates me?

[Bill Fitzmaurice]

PA subs go as much as an octave lower than bass cabs, while PA mains don't have the rising midrange typical of bass cabs. Try high passing the desk bass channel at 60 to 80Hz, if it has that capability, or cutting back on the bass EQ if it doesn't, while boosting the mids in the 2 to 2.5kHz range. 

 

If you want to be more precise get this app for your phone. https://play.google.com/store/apps/details?id=com.dom.audioanalyzer&hl=en_US&pli=1

You can use it to see the frequency response of your rig. Play an open A and take a picture of the result, C weighting, slow response. Save it and compare it to the same test through the PA. Comparing the two will show where the PA EQ needs to be adjusted. 

Edited Friday at 21:32 by Bill Fitzmaurice

[mrtcat]

8 hours ago, Bill Fitzmaurice said:

PA subs go as much as an octave lower than bass cabs, while PA mains don't have the rising midrange typical of bass cabs. Try high passing the desk bass channel at 60 to 80Hz, if it has that capability, or cutting back on the bass EQ if it doesn't, while boosting the mids in the 2 to 2.5kHz range. 

 

If you want to be more precise get this app for your phone. https://play.google.com/store/apps/details?id=com.dom.audioanalyzer&hl=en_US&pli=1

You can use it to see the frequency response of your rig. Play an open A and take a picture of the result, C weighting, slow response. Save it and compare it to the same test through the PA. Comparing the two will show where the PA EQ needs to be adjusted. 

Thanks so much Bill, that makes perfect sense. I've downloaded the app and will give it a go today. 

[dudewheresmybass]

17 hours ago, Bill Fitzmaurice said:

PA subs go as much as an octave lower than bass cabs, while PA mains don't have the rising midrange typical of bass cabs. Try high passing the desk bass channel at 60 to 80Hz, if it has that capability, or cutting back on the bass EQ if it doesn't, while boosting the mids in the 2 to 2.5kHz range. 

 

If you want to be more precise get this app for your phone. https://play.google.com/store/apps/details?id=com.dom.audioanalyzer&hl=en_US&pli=1

You can use it to see the frequency response of your rig. Play an open A and take a picture of the result, C weighting, slow response. Save it and compare it to the same test through the PA. Comparing the two will show where the PA EQ needs to be adjusted. 

Great advice!

[Al Krow]

18 hours ago, Bill Fitzmaurice said:

PA subs go as much as an octave lower than bass cabs, while PA mains don't have the rising midrange typical of bass cabs. Try high passing the desk bass channel at 60 to 80Hz, if it has that capability, or cutting back on the bass EQ if it doesn't, while boosting the mids in the 2 to 2.5kHz range. 

 

If you want to be more precise get this app for your phone. https://play.google.com/store/apps/details?id=com.dom.audioanalyzer&hl=en_US&pli=1

You can use it to see the frequency response of your rig. Play an open A and take a picture of the result, C weighting, slow response. Save it and compare it to the same test through the PA. Comparing the two will show where the PA EQ needs to be adjusted. 

 

Hi Bill, excuse my ignorance but could you elaborate on what you mean by "rising mid range" for me please?

[JPJ]

Just a thought, but before you worry about eq, are you sure you have the gain set right, and that all of your Anagram patches are putting out the same level?

[Bill Fitzmaurice]

1 hour ago, Al Krow said:

 

Hi Bill, excuse my ignorance but could you elaborate on what you mean by "rising mid range" for me please?

Look at the frequency response chart here, which is a typical high quality bass driver. Note the midrange that peaks at 2.5kHz. 

https://eminence.com/products/kappalite_3012ho#frequency-response

 

[Dan Dare]

Bill's advice is spot on, as always. I'd suggest using the HPF at 60-80hz on everything in the PA, not just the bass. You won't block all frequencies below that figure, because the roll-off will most likely be at 6, 12 or perhaps 18db per octave. It will make the overall sound a lot cleaner. People tend to over-use PA subs and put too much low frequency energy into a room, which results in mud and boom city and can excite all sorts of nasty resonances in a room that isn't acoustically treated (which applies to most gig venues).

[Bill Fitzmaurice]

Most top acts tend to over-use subs as well. I'd say three out of four FOH mixers have no idea how to mix bass. The fourth is a bass player. ☺️

[Buddster]

That's a great app, thanks Bill

[mrtcat]

So i used Bill's suggested approach to great effect.

 

Instead of playing an open A i set up a new patch in the anagram with no blocks and connected to both my amp and the mixer. I set amp eq flat and removed any eq on either the channel or main out on the mixer. I then used a pink noise generator and used the sound analyser app to listen to the pink noise through my amp and cab. I took a screenshot and then sent the pink noise through the PA. I used the global eq in the Anagram to get the PA sounding as close to my cab as possible by matching the graphic eqs as closely as I could. It was quite surprising just how much mid and treble I had to add to get them close. The greenboy cab is definitely not lacking in the mids / high mids and highs.

 

I had a gig tonight and ran the Anagram into the PA. I used a preset without a cab sim and it sounded much better. Our guitarist mixes and he noticed a considerable difference. I think it still needs a bit of fettling but its definitely much closer to what I want now.

 

 

[Bill Fitzmaurice]

The reason I said to take the RTA playing an open A is that your tone is a product of the amp EQ and the speaker. By using pink noise with the amp EQ flat you remove the amp EQ from the equation. You want the PA EQ to not only duplicate as much as possible the effect of the speaker but also the effect of the amp EQ. There's also the matter of whether the amp is actually flat when the EQ is set to flat. Most amps have built in voicing, so flat EQ may not give a flat result.   

[Downunderwonder]

The other thing to do is cut the lows from your stage monitor sound so there is no interference with the PA lows.

 

You could do that by turning well down. Otherwise you need to get fancy with the signal path, or using the main bass amp only as a monitor rather than plugging your bass into it.

[mrtcat]

3 hours ago, Bill Fitzmaurice said:

The reason I said to take the RTA playing an open A is that your tone is a product of the amp EQ and the speaker. By using pink noise with the amp EQ flat you remove the amp EQ from the equation. You want the PA EQ to not only duplicate as much as possible the effect of the speaker but also the effect of the amp EQ. There's also the matter of whether the amp is actually flat when the EQ is set to flat. Most amps have built in voicing, so flat EQ may not give a flat result.   

Understood, ill try that today and see how it goes. That may be the "fettling" I need.

[mrtcat]

3 hours ago, Downunderwonder said:

The other thing to do is cut the lows from your stage monitor sound so there is no interference with the PA lows.

 

You could do that by turning well down. Otherwise you need to get fancy with the signal path, or using the main bass amp only as a monitor rather than plugging your bass into it.

I rarely use the amp these days as we all use iems so, on most occasions, there's no stage monitor sound at all.

[mrtcat]

14 hours ago, JPJ said:

Just a thought, but before you worry about eq, are you sure you have the gain set right, and that all of your Anagram patches are putting out the same level?

I use my DAW to check and correct the levels of all of my patches so they're all very much equal in terms of output level.

[Downunderwonder]

1 hour ago, mrtcat said:

I rarely use the amp these days as we all use iems so, on most occasions, there's no stage monitor sound at all.

The OP had you using a potentially high output cab that could have been the FOH clarity difference you were missing.