On my search for amplification

[Grllle]

This is my first post but I already became an avid Talkbass Reader on my search for the appropriate amplification solution for my musical endeavors.
I would be more than happy if I could gather some advices and opinions with this.

My setup
I’m using a Moog Subsequent 37, my voice through several pedals and miced percussions as well as low tuned drums. Incorporating a looper I try to create massive walls of sound with heavy emphasis on the low end. I want the room shaking but higher frequencies are in the mix as well. After doing this at home (through headphones) for some time I moved into a rehearsal space and realized that what I’m doing is quite demanding regarding amplifier and cabinets. Going through a mixer, the existing PA (Yamaha P5000S, 2 Mackie 802 VLZ 4 and a Dynacord LM 15 sub) is hopelessly overburdened. And this is with me having a Dod Meatbox that I want to use through the Aux Send/Return to achieve 30Hz/60Hz madness.
In short: I need more of everything.

My application
I want to be able to create these massive and low sounds at loud volumes. In the rehearsal space as well as for diy gigs without house PA. If I’m really playing at one of our local venues with FOH at one time I will start another thread

Possible solutions from what I know so far
Using a commercial PA: This seemed to be the most obvious path to take at first glance. Buying some passive or active tops and subs (QSC k series for example).

Diy 1: While searching for suitable brands I stumbled upon diy solutions: Greenboy’s and BFM’s in particular. I went first for the more PA-style Bill Fitzmaurice designs, got really helpful insides on his forum and almost decided to build me 2 tops and 2 subs. A rule of thumb over there is to have a HPF at 30Hz only with 4+ Subs. It gives me serious headaches how to correctly place 4 folded horns at some of the places I could imagine playing.

Diy 2: On my search for a space-saving solution I came back to the Fearful’s: The Fearful 1515/66/1 in particular. From what I read on Talkbass this monster could fulfil my need for volume easily, maybe my requirements for LF as well with appropriate full range coverage. All in one ‘compact’ cabinet.

My questions:

• Are there other possible solutions I’m not aware of?
  
• Am I correct that a 1515/66/1 could be sufficient for my needs? @BurningSkies explained somewhere having a HPF at 35Hz with two 15s, using the shelf extension. Is there a way to lower this even down to 30Hz?
• Many threads discussing the Greenboy and Fearful cabinets are ~8 Years old but they still seem to be state of the art. Are there new driver generations out there by now that are more compact, lighter or else then the ones used in those plans?
• With the Bfm’s it seems mandatory to use a EQ as well as a limiter, using a LMS. For the Fearful’s I don’t see people talking about limiters. Why is this?
• I guess I would propel either diy solution with a class-d amp and a Dbx driverack pa2. I love bands using old, big & loud tube amps but am I right that those are not really fitting for me?

 

[Redbrangus]

My thoughts in no particular order:

You don't need any big, loud (heavy) tube amps. Class D amplification is fine.

For your purposes, I'd consider doing two 15/6/1's rather than one cab twice as big. There's a lot more versatility that way. And I'd consider supplementing them with some sort of subs if you really do want to go to 30 Hz. The drivers haven't changed much, if any, in the last 8 years. How much lighter do you imagine a bass loudspeaker could be?

If you don't have room for a bunch of big folded horns, the venue isn't big enough to need them. Folded or otherwise, getting 30 Hz response out of a bass horn requires a big ol' box. (Yes, I know about Danley, blah, blah, blah...) Amplifier power is cheap these days; while it theoretically possible to do some amazing things with folded horns, I don't much feel the need. Bass-reflex is fine and much easier to engineer and execute.

I'll hope you find these thoughts worth what they cost.

 

[Grllle]

I'll hope you find these thoughts worth what they cost.

Very much indeed, thank you!

Distributing the load on two cabs sounds reasonable. I thought of the big monolithic one because i'm unfamiliar how those 15s would interfere with each other when not setup correctly (comparable to the folded horns where placement seems to be crucial). I witnessed bands like Sleep or Sunn O))) that have several cabinets placed side by side, so i suppose this should work?

Combined with additional subs (e.g. fearful 15sub) this would be 2-4x15'', 2x6'' and 2 tweeters. I wonder if i would need some bi- or even three-amping solution for leveling this driver combination. And therefore one, maybe (god forbid) two 1515/1616/1's would be easier to control because of the defined ratio between different sized drivers.

Thanks again!

 

[Redbrangus]

Don't worry about problems arraying two cabs. Side-by-side, one on top the other, split into a stereo array -- it's all good, unless you do something seriously dumb, like displacing them fore-to-aft in relationship to the listeners. If you're obsessive about it, get a mirror-image pair and stack them on their sides with the mids together...that would pretty much be the equivalent to the 1515/66 box as far as phase relationships go. If one bigger box appeals to you, there's no reason not to go that route.

As I've reread your OP, I'm struck by two things. One is that what you're looking for is closer to being a playback system for EDM than a bass rig. The other is that you've come to the realization that getting that wonderfully rocking low end you've been grooving to in your headphones is indeed quite a demanding task to achieve in an actual acoustic space. What you're talking about is basically a high performance sound reinforcement system with an enhanced low-end -- that's not a particularly hard thing to do if you've got the frog-skins. I'm an ancient old sound guy -- if I was starting from scratch with a goal of building what you're looking for, I might start with a pair of high-performance 2-way or 3-way boxes like the 15/6/1s and supplement that with a pair of 15 subs, with the idea that I may I need to get a second pair of subs at a later date. Bi-amped at 80-100 Hz, or better yet, tri-amped with a 350-ish Hz mid crossover point. I'm too lazy to do the arithmetic for you, but I would think you could do something like that for $5K, complete with a couple of 1000-watt/ch amps with on-board DSP and a little mixer. If that's too rich for your taste, maybe look around for a pair of good used PA cabs with 2-15's and a large-format horn. I paid $1350 for a pair of JBL SRX-725s a couple of years back...they could still be still cheaper now. The older JBL SR-series cabs should be cheaper yet -- I see them in pairs on CL for $600-800 fairly regularly. Those are heavy boxes, and they don't have modern neo-dym drivers in them, but will still rock the house when driven with sufficient power. And older class-AB PA amps are also as cheap as carrots if you're even a little diligent in looking.

BTW, forget about using K-series boxes or something similar; none of that stuff would have the performance to do what you want, IMO/IME.

 

[Grllle]

This is really valuable information for me, thanks a lot!

I'm aware of stretching the thematic boundaries of the forum with my use case. As an excuse i would state that the extensive discussions about Fearful's & Co on TB were my first and biggest source of information until now. And maybe that i sometimes throw my bass played with a bow into the mix

My first estimate was spending something up to $3K for a first solution. Being able to upgrade the system successively afterwards would bring me quite close to your number.
In your opinion do amps with on-board DSP have certain advantages over using simpler amps and a separate LMS?
How to bi/tri-amping a cab and finding crossover points is something i still have to understand better. I really like the rough route you're proposing (several modular cabinets and how to amplify them)!

 

[DigitalMan]

TLDR the responses. I’m sure they’re good. I’d just say that this use case is very much in the pro audio wheelhouse and not necessarily the bass player wheelhouse. Fortunately we have many folks here who live in both worlds.

 

[Wasnex]

With EDM or similar music, you probably do need real response down to 30hz if not lower. Additionally due to the Fletcher-Munson equal loudness curves, you need more SPL at low frequencies to produce what is perceived as equal loudness. In other words, you need subs that are capable of producing substantially more SPL at their lowest range than your mid/high boxes.

Here's a chart from [Invalid or Expired Link Removed] that shows the response of the various fEARful cabs.

As you can see the cabs equipped with 15s roll of fairly steeply below about 70hz. The cabs equipped with 12s are flat to a lower frequency range, but a dual 15 will have more output than a dual 12. fEARfuls are great bass, but I don't think they are well suited for EDM. The reason fEARfuls work well with bass guitar is because bass guitar does not put out a very strong fundamental. Here's a related thread. Bass frequency/waterfall plots: what they mean to rigs

Here an image of the Fletcher Munson curve from Equal-loudness contour - Wikipedia

I suggest reading the Wiki, so you have a better understanding of what this graph is telling you.

In order to get truly impressive bass down below 30hz you will need to spend a fortune. AFAIK, most large pro sound systems do not have what is considered strong response in this range.

The JBL SRX828SP is a dual 18 sub that cost about $2,000. Specs say -3dB at 35hz and -10dbB at 29hz.

Here's a frequency response plot from the spec sheet. Max SPL is listed at 141dB.

The SRX828SP would be pretty decent with many types of music, but IMHO the low end starts to roll off a bit too high for EDM or other forms of music the require low end extension below 30hz.

 

[Grllle]

With EDM or similar music, you probably do need real response down to 30hz if not lower. Additionally due to the Fletcher-Munson equal loudness curves, you need more SPL at low frequencies to produce what is perceived as equal loudness. In other words, you need subs that are capable of producing substantially more SPL at their lowest range than your mid/high boxes.

Thanks Wasnex for your thoughts!
Even if i would classify what i do as drone (definitely not danceable ) it seems to have similar requirements for the sound system.

I came up with the 30Hz mark because of the DOD Meatbox, i would like to utilize at high volumes without blowing up my drivers. The pedal generates a sub harmonic to the input note, boosting it at 30Hz & 60Hz. I used it very carefully at low volumes with my current PA and it sounded super massive already.
Regarding the fearful's, those two frquency ranges are interestingly the first two spikes in Greenboy's graph in the 'Bass frequency/waterfall plots'-Thread.

Regarding the Equal-loudness contours you mentioned i have some questions:
If i understand it correctly the perception depends on the volume. Within a normal, quiet environment (40 phons) the blue line of the graph you've shown applies as well as an A-weighting. For concert type volumes it's more like a C-weighting that is much more flat. Doesn't that mean that if I'm hypothetically playing at 120db the sub-bass tones should be much more recognisable even with the steep roll-of of the 15s you mention?

And if i interpret the chart correctly the 1515/66 is doing 117db at 30Hz at 1600W. I read somewhere that doubling means +6db gain. That would be 30Hz at 120db+. Isn't this enough to shake my guts?

 

[Wasnex]

Thanks Wasnex for your thoughts!
Even if i would classify what i do as drone (definitely not danceable ) it seems to have similar requirements for the sound system.

I came up with the 30Hz mark because of the DOD Meatbox, i would like to utilize at high volumes without blowing up my drivers. The pedal generates a sub harmonic to the input note, boosting it at 30Hz & 60Hz. I used it very carefully at low volumes with my current PA and it sounded super massive already.
Regarding the fearful's, those two frquency ranges are interestingly the first two spikes in Greenboy's graph in the 'Bass frequency/waterfall plots'-Thread.

Regarding the Equal-loudness contours you mentioned i have some questions:
If i understand it correctly the curve changes depending on the volume. Within a normal, quiet environment (40 phons) the blue line of the graph you've shown applies as well as an A-weighting. For concert type volumes i think of it's more like a C-weighting is much more flat. Doesn't that mean that if I'm hypothetically playing at 120db the sub-bass tones should be much more recognisable even with the steep roll-of of the 15s you mention?

And if i interpret the chart correctly the 1515/66 is doing 117db at 30Hz. I read somewhere that doubling means +6db gain. That would be 30Hz at 120db+. Isn't this enough to shake my guts?

You may not necessarily need sub 30hz response. If you are creating music with fairly pure tones with little to no overtones, you may require the super low response. If your sounds have lot's of overtones, like a distorted bass guitar, the super low response is less critical.

Yes you are correct the shape of the equal loudness contour changes with SPL, but even at high SPL the bass still must be louder to be perceived as equal volume to the mids. The difference is just not as severe.

120dB at 30hz is probably not as impressive as you think it is. Per the chart I posted: To produce 100 phon you need 100dB at 1000hz and about 120dB at 30hz. Keep in mind the inverse square low: SPL drops at a rate of 6dB for each doubling of distance. So at 2 meters the SPL will 104dB, at 4 meters 108dB, at 8 meters 102dB, etc. My point is you're not going to fill up a very big space with a 120dB a 30hz.

Here's another article you may find relevant: Bass: the Physical Sensation of Sound

The other factor is we normally consider F10, which is the frequency where the output has dropped by 10dB, to be the limit of a cabs usable low frequency response. Sounds that are 10dB below the nominal level are pretty much masked; so the are not very perceptible. It looks like F10 for the dual 15 fEARful cabs is at about 37hz.

If you are curious about how the ported tunings work, Parts Express has cab tuning docs for must of the pro eminence woofers, and Greenboy designs use the 3015LF. I'll attach the cab tuning doc for the 3015LF.

I suggest paying attention to the 3015LF's excursions limits (Xmax =0.378" or 9.6mm). Another term you will want to pay attention to is Fb, which is the tuning frequency of the port. If you use the same model of driver, Fb varies with volume of the cab and dimensions of the port.

Each ported design will have a "cone displacement" chart that relates directly to Xmax, Fb, and the mechanical power handling of the cab when an appropriate high pass filter is applied.

Notice cone displacement picks up as the frequency decreases below 600hz. Below 100hz you will note there is a point where cone displacement decreases. This is where the port is starting to become resonant. The excursion will decrease towards Fb. As the frequency goes below Fb, cone excursion increases exponentially. The port is no longer resonating and the cab is no longer acting like it is sealed. Because of this, you really don't won't to force a ported design to operate very far below it's passband or you risk destroying the driver.

Each design in the attached document has a recommendation for where to set a steep high pass filter to protect the driver.

Another bit of info about how ported cabs work. At higher frequencies the cab works sort of like a sealed cab. As the frequency decreases, at some point the output of the driver will start to roll off. The port is tuned to start resonating so it fills in and smoothly extends the frequency response as the driver's response starts to roll off.

 

[crazyBassClown]

Isn't this enough to shake my guts?

You may find the "gut shaking" frequencies are a lot higher than you think. 30 Hz is more room shaking than gut shaking.
I find bass cabs rolling off quite steeply in the 70 hz area are quite good for pants flapping and gut shaking. I'd guess around the 100Hz area is where the chest thump gut shaking is.

 

[bbh]

You might want to investigate RCF FOH systems. They are used at Jones beach concerts and they can really kick while remaining very clear.

 

[Redbrangus]

My apologies for not realizing you're in Deutschland, so maybe your options are a lot different from here in the US. But I hope you're coming to grips with the potential size of a system capable of doing what you're describing. Do you have transportation for a couple of 218 boxes, along with the mid/high boxes and possibly an amp rack? Just asking.

In response to an earlier question, there's no particular audible advantage to using on-board DSP versus a separate dedicated speaker processor. I only mentioned them because they are almost ubiquitous in modern amps -- they don't add much to the cost when you're buying new class-D amps. The biggest advantage is it results in a smaller package (one less piece of rack gear) and fewer connections. Typically you just plug a full-range signal into the input and a speaker into the output -- the patching and processing is internal to the amp.

My feeling is your path is along the lines of buying a pair of fairly beefy full-range PA speakers with sufficient power to drive them to appropriate levels and then using them for a while to see how close they come to meeting your expectations. Then add additional LF components to taste. And self-powered 112+small horn boxes won't get you close enough.

 

[Foz]

build a 66 - I dare you

 

[And I]

The fEARful cabs will do what you need, for sure. I wouldn't worry about going lower than 35hz... Don't let graphs and math dictate things here. Use your ears. Even with an HPF at 50hz, with enough volume you will shake the earth. A 15/6/1 and a 15 sub seem like they would be ideal. I have two 12/6s and even they will go as low and as loud as needed for virtually any application. If you have the time and inclination to build yourself and you can get the parts where you live, you'll be very pleased...

 

[Grllle]

You may not necessarily need sub 30hz response. If you are creating music with fairly pure tones with little to no overtones, you may require the super low response. If your sounds have lot's of overtones, like a distorted bass guitar, the super low response is less critical.

I repeatedly was baffled (do cabinet builders like to say this?!) by the informative answers on TB. Having this aimed at my own project is another thing. I don't want to start every reply with a thank you but the amount of useful knowledge and cross references you, @Redbrangus and the rest is giving is crazy and super helpful. There you have it: Thanks a lot.

I probably shouldn't be so focused on the Meatbox and the 30Hz as it seems more and more that this mark is indeed not the crucial one. But i just love stuff like this:


I'm even not sure if the sub harmonics of the pedal would be cut off completely with a HPF at 35Hz or if it's more like a range boost from 30Hz to 60Hz.

I have to digest the given information in time (i found this at TB as well and grinding through it atm Welcome Secrets of Home Theater and High Fidelity).

Over at the BFM forum i was told that for example two tuba 30's must be cut off at 35Hz, with four the HPF could be lowered to 30Hz. This makes totally sense but i don't understand the math/physics behind it yet. So i just try to recapitulate including questions and probably misconceptions:
In the cab tuning doc there is the Subwoofer design with Vb 38Hz that has a HPF at 30Hz and having this F3 peak somewhere over 123db. The higher tuned version with Vb 44Hz is louder at F3. If i want to lower the HPF, i have to lower the Wattage and consequently SPL for not damaging the driver. And i compensate this loss with more drivers.
Theoretically i can do this with every cab tuning and it's just inefficient to have a driver running further away from its resonance point? So if BurningSkies has a HPF at 35Hz with two 15s i could lower it by reducing the voltage and increasing the amount of drivers for compensation?
Can i calculate the possible drop of the HPF depending on the amount of drivers and voltage limit?
@Foz probably likes the idea of running two 1515/66/1s even more.

 

[Grllle]

My apologies for not realizing you're in Deutschland, so maybe your options are a lot different from here in the US. But I hope you're coming to grips with the potential size of a system capable of doing what you're describing. Do you have transportation for a couple of 218 boxes, along with the mid/high boxes and possibly an amp rack? Just asking.

No problem at all. Most of the components i looked up are available at Thomann or other stores.
The moving is not that much of a problem for me as how to squeeze all this stuff onto a tiny stage. One or two fridges for small gigs or in conjunction with a house PA for slightly bigger venues seems to be way more easy to manage.

My feeling is your path is along the lines of buying a pair of fairly beefy full-range PA speakers with sufficient power to drive them to appropriate levels and then using them for a while to see how close they come to meeting your expectations. Then add additional LF components to taste. And self-powered 112+small horn boxes won't get you close enough.

Starting with something and then being able to expand seems to be the way to go for me as well. I just want to be sure to bet on the right horse for the start (folded horn, ported, sealed, diy, commercial) for not having to start again from scratch at some point. Your insides help a lot in this process!

 

[Wasnex]

Can i calculate the possible drop of the HPF depending on the amount of drivers and voltage limit?

Yes, but this is beyond my knowledge level.

 

[Downunderwonder]

The BFM horn subs get a lot of useable bass from a single sub driver but you need a big van to haul them.

Horns grouped with mouths together turn into one big horn which has a lower frequency response. Regular speakers in boxes don't do that.