Testing the PA Speaker as Backline Hypothesis

[TrevorOfDoom]

Well, we can always ask @agedhorse who i believe designed the cabs.
But i wasn’t trying to start a fight. My point was just that the QSC & Mesa cabs are made to do two different things. The Mesas definitely don’t have the same high end extension as the QSCs. The Mesas only go up to 12kHz, but the QSCs go to 20kHz. And yes, the QSCs have good low end, but they’re not made specifically for throwing low end like the Mesas are. And the Mesa specs are on the website and well documented, if you’re curious.

Show me the measurements that back this up? The QSC specs are well defined and recorded, but the bass cabs certainly are not.
The PA cabs have a much stronger HF response, especially off axis relative to a bass cab, and because of this may sound more bass shy when they're not.

 

[bass.slinger]

I found the opposite to be true. My Yamaha DSR15 with an Origin Effects BassRig Super Vintage sounds a little better to me than my Mesa WD-800 with a Subway 210. Frequency response on the two speakers is pretty similar - the Subway has a lower F10 but the F3 between the two is less than 2dB. With the bass output being similar, the main reason for preferring the PA speaker rig is the quality of the overdrive with the Origin SV. This is using the DI out which has an 810 speaker emulation which is critical to the sound. Using the 1/4” out (without the cab sim) sounds worse and the Mesa rig beats it. You really need a cab sim if you want a PA rig to sound like a dedicated bass amp.

That said, I use IEMs and don’t have a monitor / amp on stage anymore. The front of house sound difference between using a dedicated bass amp without PA support versus using the Origin SV DI with the PA is night and day - the PA (which is only two Yamaha DSR15s - no subs, yet) wins by a mile (cleaner, better projection, etc.).

 

[crazycloud]

And the Mesa specs are on the website

I've been designing speakers for decades, which is why I want to see the measurements before I comment further, especially polars not just an F3 and F10 on axis.

And my point was that because someone believes something sounds a certain way, doesn't mean that's what they're actually hearing, ie, X sounds bassier becase a midbass hump with less LF response can give that impression, as can a different HF response.

And for the record, I'm not knocking any particular set of speakers here, or anyone's preference, just commenting on the psychoacoustics.

 

[Passinwind]

Here are the settings, which I have found most useful for using the .2 cabs as monitors. My recollection when testing different settings was that the “Bass Amp” setting was kind of lame. IIRC, the intent for that input setting was for use plugging the instrument directly into the input. I used a Sushi Box PMLE in front of the .2’s for this test. But, I would need to revisit. I’ll check the next few days, and post up the result.

View attachment 7429577
View attachment 7429576

Cool, thanks. I have a fair amount of experience plugging straight into the board, often with no DI, with various friends’ K2 based FOH sytems at open mics. That generally means 50-100 audience members and fairly often no drums though. For me it works just as well as many of the typical backline rigs I see, but not quite as well as the better ones.

 

[Wasnex]

I've been designing speakers for decades, which is why I want to see the measurements before I comment further, especially polars not just an F3 and F10 on axis.

I posted this image earlier.

Pretty sure the red trace is not the natural response of the cab. The frequency response specs appear to be based on this curve.

AFAIK, it's achieved by applying a lot of EQ. IME using this sort of curve may help the low end sound fuller, but it doesn't necessarily result in high-quality bass.

 

[dbsfgyd1]

The short answer for TL;DR challenged is that PA speakers don’t quite get what backline cabs deliver for me. Yet.

For the past year, I’ve been gigging fairly large outdoor stages and animal club stages using a QSC K10.2 for both bass monitor and vocal monitor. I have finally accepted the idea that the PA is now my amplifier. So, I have been evolving my pedal board preamps to produce both a sound I prefer in the PA mains, and a close facsimile in the monitor. That way I hear pretty much what the audience hears.

Last summer, I had a road trip reunion gig, and acquired a QSC K12.2 with the concept that I could put the same sound on a backline. The sound system when I left home was a bit of an unknown; and I was trying to create options. The pair of .2’s was stacked on the backline as things went, and seemed to perform well enough. Except the sound person who eventually turned up asked me to reduce the level to monitor level (as usual these days); so, it wasn’t much of a test.

Back on the home front, my primary backline capability has been a pair of Mesa 112/115 stacks. They don’t leave home much any more; I dislike the 2 hand carry down the basement stairs; and I’ve been toying with the idea of a second K10.2/K12.2 stack as a direct substitute.

So, I put the two stacks side by side this morning while the wife factor was at breakfast with a friend.

View attachment 7429502

The comparison was interesting. Volume differences were almost negligible. But, the main thing was that the Mesa stack sounded like the massive sound was coming from deep within the cabs, while the .2 stack sounds more like the sound is coming directly off the front. So, kind of 3D vs 2D. From a bedroom, or living room in this case, cork sniffing perspective, the Mesa stack sounds altogether more bass.

Now, I will admit that I am still learning how to use the .2 speakers. A year ago, I still hadn’t figured out the volume aspect. Is it possible to recreate the voicing aspect to give the projection more depth? Quite possibly. But, that is not in my kit of tools ATM. So, for the moment, the unchecked box for the PA speakers as backline is depth of sound, not volume.

I’ll keep trying. One thing for those who like to condemn people for age related afflictions, is that while the weight of Mesa cabs on the schlep is NOT my problem; carrying those cabs with a two hand carry down basement stairs, where I can’t see the stair treads challenges my balance. This is not a small factor at 2AM coming home from a gig. The .2 cabs are both one handers going down the stairs. FWIW.

In this day of FOH support, I just worry about have what I need to function, be it an amp/cab rig, a wedge or IEM earbuds, or whatever it is, it’s my monitor. I don’t need a high fidelity experience to be effective.

Now, I don’t use effects and can understand artists that use them have a vested interest in having them heard in the house. But if I did use effects, I’d be having a conversation with a sound sample with the sound tech before the gig.

 

[crazycloud]

I posted this image earlier.

Just so people understand, this is showing the response curves with a high pass filter on to allow it to be crossed over to a subwoofer.

Pretty sure the red trace is not the natural response of the cab.

It's likely the one the designed intended as it says 'full range' ie without the HPF for the xover. It has a DSP in it, so what does 'natural response' mean? To me it's the one without any further EQ added, as the designer intended it to be used 'flat'. But I don't have time to read the manual right now to confirm.

 

[T748]

If the problem is the two handed carry down the stairs, try a "stair climbing hand truck". Amazon sells them for cheap.

 

[bucephylus]

Just to clarify…

I have been doing 100% of my recent gigs using the K10.2 with various high quality board mounted preamp/DI’s. I am happy with this for my stage mix; since it pretty much replicates the character of the FoH projection heard by the audience.

At the same time, I have retained my backline capability, because…well, you never know.

The purpose of my test was to determine whether I could be satisfied with the monitor speakers acting as backline. This is a personal preference thing. So far, my answer is “no.”

As to my test being “flawed” or whatever; I was merely testing my prefs. Someone else may reach different conclusions based on their prefs.

I am perfectly happy with the K.2 boxes as monitors. I am perfectly happy with the Mesa boxes as backline cabs. Although none of my current gigs require a backline capability, I am neither ready to give up my backline cabs nor to substitute the monitors on the backline. But, I will also admit that I haven’t fully explored the DSP capability in the monitors.

Theory is great. But we used to have a saying in R&D that I still find useful; “Theory guides, Data decides.”

Carry on.

 

[bucephylus]

If the problem is the two handed carry down the stairs, try a "stair climbing hand truck". Amazon sells them for cheap.

A good suggestion; thanks.

Though we have a finished basement; and the spreaders are nicely finished oak. So, I’d be hesitant to use one of those trucks due to wear and tear.

 

[agedhorse]

I posted this image earlier.
View attachment 7430275
Pretty sure the red trace is not the natural response of the cab. The frequency response specs appear to be based on this curve.

AFAIK, it's achieved by applying a lot of EQ. IME using this sort of curve may help the low end sound fuller, but it doesn't necessarily result in high-quality bass.

Correct, there is no way the red trace can be flat, IME it does have substantial internal eq applied within its DSP which can't be done with just a passive speaker. There is also a penalty to be paid with regard to a reduced a maximum SPL.

 

[agedhorse]

Just so people understand, this is showing the response curves with a high pass filter on to allow it to be crossed over to a subwoofer.

It's likely the one the designed intended as it says 'full range' ie without the HPF for the xover. It has a DSP in it, so what does 'natural response' mean? To me it's the one without any further EQ added, as the designer intended it to be used 'flat'. But I don't have time to read the manual right now to confirm.

If you understand the science and math, you would immediately recognize that it's impossible for the red curve to be without enhancement eq added w/ in the DSP.

 

[Wasnex]

Just so people understand, this is showing the response curves with a high pass filter on to allow it to be crossed over to a subwoofer.

AFAIK this does not apply to the red curve. I assume it does apply to blue (80hz) maroon (100hz), and green(125hz). I also assume the natural (unprocessed) response of the cab most resembles the blue curve...or possibly even the maroon curve.

EQ can be used to flatten out response or even boost the lows, but it can't be used to increase the peak SPL the cab can produce at a given frequency. Applying the boost required to get the default response curve will likely result in the K12.2 having limited headroom with bass guitar. I also think it may result in marginal sound quality, as I suspect much of the boost is applied over the active range of the port.

It's likely the one the designed intended as it says 'full range' ie without the HPF for the xover.

Yes the graphic, which is from the K.2 Spec Sheet, says it's the default setting. IME, most speakers I have seen with that sort of preset response curve label it as Deep, Bass Boost, Dance, etc. IME default curves usually tend closer flat response.

This is the list of K.2 presets:

I am not aware of published curves for these presets, which IMHO could be very helpful.

 

[crazycloud]

If you understand the science and math, you would immediately recognize that it's impossible for the red curve to be without enhancement eq added w/ in the DSP.

I already said it had a DSP onboard and by implication that is the response curve the designer wanted for the speaker.

 

[agedhorse]

I already said it had a DSP onboard and by implication that is the response curve the designer wanted for the speaker.

Sorry, that wasn't clear in your post.

 

[Wasnex]

that is the response curve the designer wanted for the speaker.

The first time I saw the response curve it was sort of a *** moment. I perceive the K series is being high quality for the market segment. To me that particular response curve seems like they are catering to the DJ market, rather than the pro sound market.

I believe the default setting for the original K series was fairly flat, but they had a Deep setting with hyped lows. So apparently they have changed their philosophy a bit.

 

[agedhorse]

The first time I saw the response curve it was sort of a *** moment. I perceive the K series is being high quality for the market segment. To me that particular response curve seems like they are catering to the DJ market, rather than the pro sound market.

I believe the default setting for the original K series was fairly flat, but they had a Deep setting with hyped lows. So apparently they have changed their philosophy a bit.

It's the classic consumeriztion of a technology to an evolving market...

 

[crazycloud]

Sorry, that wasn't clear in your post.

Poor writing on my part as I dashed the post off quickly as I was on my way somewhere.

 

[Omega Monkey]

I have a super easy solution for you. Use the Mesa cabs, and simply don't take them into the basement at 2 am. Leave them by the front door or whatever and take them down in the morning.

Problem solved.

 

[coreyfyfe]

I found the opposite to be true. My Yamaha DSR15 with an Origin Effects BassRig Super Vintage sounds a little better to me than my Mesa WD-800 with a Subway 210. Frequency response on the two speakers is pretty similar - the Subway has a lower F10 but the F3 between the two is less than 2dB. With the bass output being similar, the main reason for preferring the PA speaker rig is the quality of the overdrive with the Origin SV. This is using the DI out which has an 810 speaker emulation which is critical to the sound. Using the 1/4” out (without the cab sim) sounds worse and the Mesa rig beats it. You really need a cab sim if you want a PA rig to sound like a dedicated bass amp.

That said, I use IEMs and don’t have a monitor / amp on stage anymore. The front of house sound difference between using a dedicated bass amp without PA support versus using the Origin SV DI with the PA is night and day - the PA (which is only two Yamaha DSR15s - no subs, yet) wins by a mile (cleaner, better projection, etc.).

I think you hit on an issue with these types of comparisons here - you're talking about the F10 and F3 of the PA speaker but also say you prefer the sound of the PA speaker when you've applied a cab sim to the DI signal. Wouldn't a more appropriate comparison be the F10 and F3 of the 810 cab sim to the mesa in this case? I would absolutely take a cab sim - especially when your point of emphasis is the quality of the overdrive - over direct into the PA speaker. The difference, in my reading of your post, is then how the OE cab sim treats the overdrive versus how that overdrive sounds through your 1/4" out into the WD800 and cab. I would think the top end roll off of the 810 is going to be very different from the subway 210. Personally I don't like an overdriven sound without a speaker sim added to the end, I run all of my anagram presets with a cab sim on the back end one of the selling points on the mesa amps for me was the mild cab sim on the DI out to smooth out the signal.