How do I find out how to EQ my bass 'flat'?

[Lowtonejoe]

I was curious to know if there was a way to find out how to eq my bass so that it has a 'flat' output...meaning even response from top to bottom.

Sure, I know, use an eq...but how do you know where to eq it?

Any ideas?



Joe.

[line6man]

I'm not sure what you're asking?

Set your EQ pots to the center detent, and that's flat.
Boost-only EQs should be set to "0," and cut-only EQs should be set to "10."

If you want an even frequency response overall, you would use your ears, and possibly a spectrum analyzer.

[Lowtonejoe]

Originally Posted by line6man

I'm not sure what you're asking?

Set your EQ pots to the center detent, and that's flat.
Boost-only EQs should be set to "0," and cut-only EQs should be set to "10."

If you want an even frequency response overall, you would use your ears, and possibly a spectrum analyzer.

Right, the second part.

Basically I want to somehow see the output of my bass on some kind of graph that shows the overall tonal shape of the output.

You know how some basses are more midrangey than others or more scooped than others? I want to be able to see that and correct for it.

I guess a specrum analyzer might be the answer...I don't know. Heh heh, that's why I'm asking.

And if the answer is a piece of software, do you or anyone else know what is available to do what I want it to?

Thanks!



Joe.

[line6man]

Originally Posted by Lowtonejoe

Right, the second part.

Basically I want to somehow see the output of my bass on some kind of graph that shows the overall tonal shape of the output.

You know how some basses are more midrangey than others or more scooped than others? I want to be able to see that and correct for it.

I guess a specrum analyzer might be the answer...I don't know. Heh heh, that's why I'm asking.

And if the answer is a piece of software, do you or anyone else know what is available to do what I want it to?

Thanks!



Joe.

Use a spectrum analyzer then, I guess.

I've been meaning to buy a spectrum analyzer for years now, but they are expensive pieces of equipment, so I usually just use software.

I've started to do very quick comparisons of the frequency responses of pickups lately by playing my bass into SONAR with the Waves PAZ Analyzer plugin.

[Lowtonejoe]

Originally Posted by lbwdog

You want to set your bass flat, or your amp flat?
There's no way to set the bass "flat" since it is the sound source. Well theoretically, you would just turn your tone pot wide open on a passive bass. That means the signal from the pickups is not having the treble rolled off.

The problem with setting an amp flat is that each bass amp manufacturer builds in a distinct voicing in their amps. If you were plugged into a high quality hi-fi preamp + poweramp, you would remove all tone controls from the circuit or put them at 12:00.

Yes, I want to set my bass flat.

Sure you can. We adjust our eq's all the time.

Setting knobs at 12:00 wont be the answer and neither will bypassing a preamp or tone controls.

And I already understand the cab thing. I have some very tonally different cabs.

Hmm...



Joe.

[Lowtonejoe]

Originally Posted by line6man

Use a spectrum analyzer then, I guess.

I've been meaning to buy a spectrum analyzer for years now, but they are expensive pieces of equipment, so I usually just use software.

I've started to do very quick comparisons of the frequency responses of pickups lately by playing my bass into SONAR with the Waves PAZ Analyzer plugin.

HOLY COW MAN!

Yeah, something like that.

I have a very old copy of Sonar...it's not even installed.

I wonder what else is available on the internet...for free...hopefully.



Joe.

[M0ses]

Define "flat"???? Why do you want to "correct" a bass' voice. What are you going to correct it to?

[Lowtonejoe]

Originally Posted by M0ses

Define "flat"???? Why do you want to "correct" a bass' voice. What are you going to correct it to?

I already did.

Because I want to.

To whatever I want.

Now can you help?



Joe.

[line6man]

Originally Posted by M0ses

Define "flat"???? Why do you want to "correct" a bass' voice. What are you going to correct it to?

It isn't possible to have a flat-response output from a bass, that's not what "flat" means. It's only possible to reproduce the signal you have at the output of a preamp or some other circuit, active or passive, without any increase or decrease in amplitude at any frequency from what was present at the output from your pickups. Essentially, a flat-response means that the output is equal to the input, albeit sometimes at a different overall amplitude. A truly flat frequency response from a bass would be something like white noise, where every frequency is present at an equal amplitude.

[Pilgrim]

You have a more complex challenge than you think. For the sake of discussion, let's say you're defining "flat" as the output from your instrument with absolutely no alternation to the frequency response of the signal.

First, the bass's output won't be "flat". Pickups and electronics impose their own frequency response curve on the output....but under the definition I suggested, alternations to that output imposed by the electronics in the bass are not meaningful.

Second, the amp will have its own voicing, so "flat" (neutral settings on the EQ) do not necessarily mean that the amp is passing through sound without alternation.

Finally, there's the frequency response of the speakers you play through...certainly not "flat".

If you can get in touch with the manufacturer of your amp and talk them into telling you what the closest setting is to "flat" - defined as performing no frequency response alternation at all - that would be a place to start. Of course, it doesn't affect the other two factors in the sound reproduction process.

[M0ses]

Originally Posted by Lowtonejoe

You know how some basses are more midrangey than others or more scooped than others? I want to be able to see that and correct for it.

This is what I'm questioning, guys.

[Lowtonejoe]

Originally Posted by line6man

It isn't possible to have a flat-response output from a bass, that's not what "flat" means. It's only possible to reproduce the signal you have at the output without any increase or decrease in amplitude at any frequency. Essentially, a flat response means that the output is equal to the input, albeit sometimes at a different overall amplitude. A truly flat frequency response would be something like white noise, where every frequency is present at an equal amplitude.

I see your point, however...

Flat relative to this thread would be to somehow eq the bass so that all relavent frequencies are at the same percieved volume.



Joe.

[M0ses]

Originally Posted by Lowtonejoe

I see your point, however...

Flat relative to this thread would be to somehow eq the bass so that all relavent frequencies are at the same percieved volume.



Joe.

Ha! I knew it. He's crazy after all.

[Lowtonejoe]

Originally Posted by M0ses

Ha! I knew it. He's crazy after all.

Thanks for being such a helpful contributor.



Joe.

[Pilgrim]

Originally Posted by Lowtonejoe

I see your point, however...

Flat relative to this thread would be to somehow eq the bass so that all relavent frequencies are at the same percieved volume.



Joe.

Unfortunately that's not a realistic goal, because human hearing does not perceive low frequencies to be at the same volume as higher frequencies, even when they are in fact the same volume.

What you will perceive will ALWAYS require the lower frequencies to be louder than the higher frequencies, even though your ears won't tell you that.

It might be interesting to get a Sound Pressure Level (SPL) meter and try playing notes at radically different points on the bass, meanwhile adjusting the amplification so that you perceive those notes to be at the same volume. The actual SPL should be somewhat different, requiring the lower notes to be played louder in order for you to perceive them as being at the same volume.

I understand the intellectual exercise in what you're pursuing, but there are complicating factors.

[M0ses]

Originally Posted by Lowtonejoe

Thanks for being such a helpful contributor.



Joe.

Have you ever heard a tone with all harmonics at an equal perceived volume? I don't think it sounds like you think it does.

[Pilgrim]

Famous quotations:

http://www.youtube.com/watch?v=G2y8Sx4B2Sk

[Coolhandjjl]

You will need a PC, a calibration mic, a mic mixer with phantom power, and RTA software. Lots of RTA freeware out there, so with the special mic and mixer, probably talking less than $100, unless your PC has a sound card not up to the task. Then you may need an outboard USB sound card, again, not too expensive. To learn how to use all this stuff, drop in at the Bill Fitzmaurice forums. He designs both backline and PA speakers. Lots of sound support guys along with musicians hang there.

[Lowtonejoe]

Originally Posted by Pilgrim

Unfortunately that's not a realistic goal, because human hearing does not perceive low frequencies to be at the same volume as higher frequencies, even when they are in fact the same volume.

What you will perceive will ALWAYS require the lower frequencies to be louder than the higher frequencies, even though your ears won't tell you that.

O.k., I see what you are saying. And by that I mean I agree.

But ultimately it is about 'percieved' sound, not 'measured' sound.

Is there some kind of spectrum analyzer that you can factor in the extra required amplitude to show a representation of what would be heard as 'flat'?

If there is a baseline for hearing tests I am sure someone can come up with a baseline for 'flat'. I think.

It might be interesting to get a Sound Pressure Level (SPL) meter and try playing notes at radically different points on the bass, meanwhile adjusting the amplification so that you perceive those notes to be at the same volume. The actual SPL should be somewhat different, requiring the lower notes to be played louder in order for you to perceive them as being at the same volume.

Whew! Yeah, that would be one way. And it would probably work.



Joe.

[Staccato]

Yep, I'd like some idea about how to hear this on bass, or amp as well.

TB group think seems to be that we're all supposed to be able to adjust EQ 'flat' with no particular effort involved...

Call me EQ Challenged!