Help me understand sound reproduction

[RedHotFuzz]

NOOB ALERT HERE. So I’m looking at PA speakers to serve as a full-range “practice/jam” solution. I have my eye on the Electro-Voice ZLX G2 series as the price is right and the onboard Bluetooth would be helpful as I stream backing instrument stems from Logic Pro on my iPad. In debating between the 12” and 15” versions of this speaker and looking at the specs, I’m wondering how frequency range comes into play. For example the 12” model shows 48 Hz as its low whereas the 15” shows 42 Hz. But if an open-E string on bass guitar is at a frequency of 41 Hz, how do either of these speakers reproduce an open-E at all??? I’ll happily don a dunce cap while someone explains.

 

[gln1955]

This thread may be helpful.

https://www.talkbass.com/threads/frequency-response.1583280/

 

[WayneP]

A bass guitar note is not a pure-tone sine wave. It is a complex tone with harmonics layered along with the fundamental. Thus, a speaker that can’t fully reproduce the fundamental will still be producing the harmonics; and as such can reproduce notes audibly. For instance, there no shortage of bass guitar cabinets with frequency response rolling out well above the lowest notes of a 4- or 5-string bass. Yet, the player (and audience) can still hear those notes just fine.

Regards,
Wayne A. Pflughaupt

Ecclesia: Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Make Your Own Cables: A How-To Guide
Administrator, Official Pedulla Club #45
Administrator, Official Heartfield Club #36
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My Rig: Stage and FOH Friendly
My Basses

 

[RedHotFuzz]

A bass guitar note is not a pure-tone sine wave. It is a complex tone with harmonics layered along with the fundamental. Thus, a speaker that can’t fully reproduce the fundamental will still be producing the harmonics; and as such can reproduce notes audibly. For instance, there no shortage of bass guitar cabinets with frequency response rolling out well above the lowest notes of a 4- or 5-string bass. Yet, the player (and audience) can still hear those notes just fine.

Regards,
Wayne A. Pflughaupt

Ecclesia: Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Make Your Own Cables: A How-To Guide
Administrator, Official Pedulla Club #45
Administrator, Official Heartfield Club #36
Administrator, Official Tobias Club #133
Administrator, Official Pre-Gibson Tobias Owners Club
Fretless Club #943
Big Cabs Club #23
My Rig: Stage and FOH Friendly
My Basses

Great clarification, thanks. Yes, I assumed there was much more at work here as I can hear the bass guitar part even on my pathetic iPhone speaker and thus naturally wondered just how much practical impact is found in a mere 6 Hz difference in range (42 Hz vs 48 Hz) between the 12” and 15” versions of this particular EV PA speaker as I try to decide between the two.

 

[Wasnex]

IME, when comparing 15s and 12s from the same series of cabs, the 15 will typically be capable of fuller lows and slightly higher SPL. The 15 won't necessarily sound better across the mids. It may and it may not. It can be a matter of choosing the compromise that best meets your needs.

The down side is 15s tend to be bigger and heavier, which makes it harder to lift them up on tripods.

I generally prefer smaller mid/high cabs and subs. Since subs do the heavy lifting down low, they may reduce some of the headroom advantage the larger cabs have with full-range program material.

 

[Wasnex]

Great clarification, thanks. Yes, I assumed there was much more at work here as I can hear the bass guitar part even on my pathetic iPhone speaker and thus naturally wondered just how much practical impact is found in a mere 6 Hz difference in range (42 Hz vs 48 Hz) between the 12” and 15” versions of this particular EV PA speaker as I try to decide between the two.

The 6 hz difference doesn't necessarily tell you the full story. In general the specs most companies publish aren't going to tell you what you need to know. Ideally you need graphs that show the max SPL each cab can produce across the low-frequency spectrum. AFAIK frequency response plots tend to show you how a cab performs well below it's max output. These plots can sometimes be pretty misleading.

 

[DirtDog]

Tech specs and physics aside, I can tell you that the 15” ZLX does a pretty decent job for handling bass guitar. I used a pair of these for a gigging country band for years. I went ampless during that period.

 

[Jogobass]

Speakers have a reduced response at those low frequencies. It doesn't mean the fundamental isn't there.

 

[mdlewis]

You don't need to have the fundamental in a harmonic series present to actually perceive it - your brain will "recreate" it. This was discovered in the 19th century by Hemholz. Additionally, Human hearing also rolls off pretty rapidly in the 20-40 Hz range depending on age and health.

So the bottom line is that an extreme low end flat response is not necessary to provide a pleasing audio experience and hear the pitch of bass guitar. It might be a reasonable starting point for some applications, but I've always considered subwoofer FOH stuff to be the realm of experts due to the numerous challenges (power handling, cross-over, room artifacts etc.). I've played with a number of musicians who really hate the extreme low end of some of the more modern PA systems with large subs who claim it sounds "unnatural" and try to convince the sound man to turn them off.

 

[A Bass And Its Boy]

Not to mention the fact that even if you have a cabinet that CAN reproduce the fundamental, it often gets muddy—lots of bassists (myself included) will use a high-pass filter (also called a low-cut filter) to roll off any frequencies below 80Hz or so. This makes the bass sound a little punchier which lets the audience hear it more clearly, which counterintuitively makes the bass sound lower and beefier.

 

[LowActionHero]

A 15 is 3 more than a 12.

Init?

MOST kidding aside, I'd always go with the 15 for fuller lows no matter how slight - you can always turn it down.

All 12 PAs I've heard sound weak, but I'm far from a professional and out of the loop with newer ones

 

[RedHotFuzz]

Not to mention the fact that even if you have a cabinet that CAN reproduce the fundamental, it often gets muddy—lots of bassists (myself included) will use a high-pass filter (also called a low-cut filter) to roll off any frequencies below 80Hz or so. This makes the bass sound a little punchier which lets the audience hear it more clearly, which counterintuitively makes the bass sound lower and beefier.

And confusingly one might assume (incorrectly) that filtering sub-80Hz frequencies would eliminate your E, A and D strings entirely.

 

[brianrost]

When the low frequency is spec’d at 42 or 48 Hz, it’s not a brick wall. It just means that the level of that frequency will be 3 dB less than the mid band and at lower frequencies, the level will continue to decrease. A speaker that can truly hit 42 Hz will give you the E fundamental just not as loud.

In the powered cab version, the ELX cabs include EQ tweaking to provide different responses. From the ELX G2 15P spec sheet, regardless of EQ the response is relatively flat from 200 to 10K. In the “music” and “club” modes, due to a bass boost at 40 Hz it’s down about 5dB which is significant but there is still some signal. Other modes provide various low and high boosts:

 

[sheesh]

And confusingly one might assume (incorrectly) that filtering sub-80Hz frequencies would eliminate your E, A and D strings entirely.

Ha ha, I am still trying to figure this one out. It's like, why does the bass in this song sound great in my headphones, but I can't get my amp to sound like that!

 

[FullumMusic]

Ha ha, I am still trying to figure this one out. It's like, why does the bass in this song sound great in my headphones, but I can't get my amp to sound like that!

Filtering below a frequency doesn't completely eliminate those frequencies.

Filters begin to roll off at the cutoff frequency, starting with no cut, and gradually cutting more as you go down. They roll off at a rate usually in the filter's name.
So a -12dB/Oct rolloff means you set the cutoff to 80Hz, and for every octave below that, you lose 12dB:
80Hz : 0dB reduction
40Hz : 12dB reduction
20Hz : 24dB reductio
and so on down the frequency spectrum.

(This is ignoring any resonant peaks that might exist at the cutoff frequency for ease of understanding.)

----

As to why your bass amp and bass in a song in your headphones sound different, it's because everything about them is different. This is why tone-chasing is a fool's errand and close enough should usually be good enough in most cases.

1 - Bass cabinets pumping out sound waves into the air and headphones injecting sound directly into your ear are always going to sound different.

2 - What you hear in the recorded bass probably isn't a bassist's rig. It's their bass played by them, into their signal chain, into a DI, maybe the cab mic'd and through a mic-pre too which both impart some tone, through some sort of channel preamp, through whatever onboard gear the studio might be running it through, through whatever plugins it might be run through as inserts (in series with the signal) or through returns (in parallel), adjusted for a mix, in a mix, then mastered, through whatever audio system you're using to play back that song.

You bass amp will sound like you playing your bass through your signal chain through your amp/cab in your room. It'll never sound exactly the same as in the mixed and mastered song, and a mixed and mastered song will never sound the same as you playing through your amp. It won't even sound exactly the same if the bassist from the recording was playing through their rig.

 

[RedHotFuzz]

Filtering below a frequency doesn't completely eliminate those frequencies.

Filters begin to roll off at the cutoff frequency, starting with no cut, and gradually cutting more as you go down. They roll off at a rate usually in the filter's name.
So a -12dB/Oct rolloff means you set the cutoff to 80Hz, and for every octave below that, you lose 12dB:
80Hz : 0dB reduction
40Hz : 12dB reduction
20Hz : 24dB reductio
and so on down the frequency spectrum.

(This is ignoring any resonant peaks that might exist at the cutoff frequency for ease of understanding.)

So…in theory this would cause a notable impact to the open E string but not to the G string (lol) played at the 22nd fret?

 

[mambo4]

how do either of these speakers reproduce an open-E at all??? I’ll happily don a dunce cap while someone explains.

In my experience accurate powerful reproduction of frequencies that low ( say 100 Hz and down ...) is generally unnecessary, unclear mud
It's for stadiums and "cars that go boom" not parse-able musical notes. LPF pedals for clarity are popular for a reason.

the frequencies that , to me, sound like a nice thick fat bass tone are closer 250-500 hz.
The upper harmonics, not the fundamental, are where humans recognize bass notes.
Linked a video that explains different frequencies well in this post

 

[FullumMusic]

So…in theory this would cause a notable impact to the open E string but not to the G string (lol) played at the 22nd fret?

Yes and no.

If we're playing pure Sine waves, yes. A pure Sine wave has no harmonic structure. It's purely the fundamental frequency. So a Sine at Low E (approx 40Hz) and a Sine at the first octave up E (approx 80Hz) played at the same level, run through a -12dB HPF, the Low E would be 12dB lower in volume than the +1 Oct E.

But, when you play a Low E, it's not just the fundamental frequency of 41.2Hz that you hear. In that one note there's also overtones aka harmonics, going up the Harmonic Series. The varying levels of those harmonics are what gives notes unique tones. It's why a bass sounds like a bass and a clarinet sounds like a clarinet.

- The First Partial of the note is the Fundamental Frequency (41.2Hz).
- The Second Partial is the second harmonic, the first overtone up at 82.4Hz.
- And it keeps going up the Harmonic Series until there's no more harmonics in the note.

So if you set the HPF to 80Hz and play a low E, you're not just reducing the entire volume of the Low E. You're only reducing the level of its fundamental frequency by -12dB, but all of its harmonics are full volume.

 

[sheesh]

Filtering below a frequency doesn't completely eliminate those frequencies.



1 - Bass cabinets pumping out sound waves into the air and headphones injecting sound directly into your ear are always going to sound different.

2 - What you hear in the recorded bass probably isn't a bassist's rig. It's their bass played by them, into their signal chain, into a DI, maybe the cab mic'd and through a mic-pre too which both impart some tone, through some sort of channel preamp, through whatever onboard gear the studio might be running it through, through whatever plugins it might be run through as inserts (in series with the signal) or through returns (in parallel), adjusted for a mix, in a mix, then mastered, through whatever audio system you're using to play back that song.

Thanks for the detailed response. I appreciate your taking the time to write. I was half serious, half joking.

The half joking part was the head phone vs amp aspect. Studio recording as you pointed out in (2) is a combination of many factors. How many bass tracks came from just plugging a bass into the board. Bass cabs and headphones are crazy different.

The half serious part was how can I get closer to that good tone in my head, (good tone as opposed to perfect tone).

I think the part that I still am learning about is the EQ / parametric / filter stuff. Modern amps with pre amps, pedal with pre amps, parametric eq pedals, roll off / shelving . . . the list goes on and on. Some amps are flat with "everything at noon", other's are not. Some amps are more hi-fi, less voiced, some are more voiced. So thanks for your writeup.

 

[FullumMusic]

Thanks for the detailed response. I appreciate your taking the time to write. I was half serious, half joking.

The half joking part was the head phone vs amp aspect. Studio recording as you pointed out in (2) is a combination of many factors. How many bass tracks came from just plugging a bass into the board. Bass cabs and headphones are crazy different.

The half serious part was how can I get closer to that good tone in my head, (good tone as opposed to perfect tone).

I think the part that I still am learning about is the EQ / parametric / filter stuff. Modern amps with pre amps, pedal with pre amps, parametric eq pedals, roll off / shelving . . . the list goes on and on. Some amps are flat with "everything at noon", other's are not. Some amps are more hi-fi, less voiced, some are more voiced. So thanks for your writeup.

Welcome

I feel like everything on TB is half serious half joking. At least for me.

But yeah, heheh... Whenever i'm around a new piece of gear, like using amps at a rehearsal studio or at a live jam or something, i'll look up the user manual on my phone and see how they designed their EQ, and where Flat is for that EQ, and then i put it there so i can hear how everything sounds without any EQ, and then adjust accordingly.

It's just the nature of the game because every EQ is different, and they're all labeled differently. Some are obvious with +/- 0 clearly labeled with an detent and i know it's a cut/boost EQ with flat at 0. Others are labeled 0 - 10 and i'm like, is this boost only with 0 flat? Is it cut/boost with 5 flat? Who knows? Guess i'll look it up. They could have made my life easier by using intuitive design but so it goes.

Another issue is, like you said, there's a half billion pieces of gear in a bass player's signal chain these days, from the onboard preamp all the way through the pedals to all the features on the amp. Half those have an EQ on them. Even if you're just going Active Bass -> Preamp Pedal -> Amp, and all 3 have an EQ, which do you use? (As with everything in music, it depends.) But on the music production/sound engineering side of things, i've seen too many bassists with all 3, and all 3 have their EQs set. It's redundant and often doing more harm than good to their tone. The worst is when they have one EQ set with a huge scoop boosting the lows and highs, and the other with a huge mid boost. And it's like, you're essentially cancelling out any EQ curve, and essentially just boosted the gain. Just turn up the gain or volume if you want it louder.

When musicians have a lot of gear with a lot of knobs, they tend to turn them all, when often one broad EQ bump or cut is all that's needed (and would sound better than surgically tweaking everything at every stage)