Bass player looking for guidance!

Howdy, and welcome to the forum.

As a recently born-again bassist, I've been wondering similar things for the future. At present my K140 based rig does fine.

I looked up the specs of the Beta 12's, and whilst the efficiency and box size are good, the Xmax and volume displacement are poor at 0.8mm and 42cc. For bass you need to move a lot of air, esp if you are playing near the drummer, doubly so if he/she pounds them hard. With a pair of B12's you're only going to be able to move about 100cc of air, at least a 5th of what you'll probably need. The B12s also have weak motors which won't help transient ability especially when playing loud.

<b>the second question, which HF driver will fill these requierements, I was considering eminence PSD2002 compresion driver. The third question, will this system give me a good transient response?</b>

A horn loaded compression driver won't lack for transient response. I've never used the PSD2002, but it has a good reputation. I have used plenty of other 1" drivers though and my fave is the Beyma 380. My suggestion for a flare would be the JBL 2370 or the P.Audio copies which are indistinguishable from the originals at a fraction of the price.

For the xover, it's hard to tell what will sound best, but a 1.5k - 2k frequency should have you close. Slope should be a minimum 12dB/oct at 1.5kHz, and higher order if you cross lower. If you can solder, or can get someone to build it for you, an option might be for a small poweramp for the CD and an active xover. It's easier and cheaper to dial in an active xover than a passive one It'll also make it easier to match the different sensitivities. You can sometimes pick up 2nd hand Pro xovers for small prices. An active xover will allow you to roll off the top of the cone driver to get the best sound, without putting a choke in series with the drivers and messing with their transient ability. push a cone driver too high in frequency and it will break up and distort. Good thing for guitar players, but not neccessarily for bass.

<b>The third question, will this system give me a good transient response? I'm a big Slap/Pop tecnique lover so good transient response is a must .</b>

Big grunty cone drivers with a lot of volume displacement and the 1" driver above them should be good.
Victor Wooten and Stanley Clarke are two of my fave players.

<b>I selected these drivers because of the relative low box volume that they need and the good F3 predicted, but feel free to suggest me any other drivers and/or configurations especially on the HF unit.</b>

Theres a rule called Hoffman's Iron Law. It means that you can have 2 of these at any one time: efficiency, box size (small), deep bass. So if you want it to be efficient (ie loud) and have relatively deep bass (bottom E is 41Hz) then it's going to be big. Few bass rigs I've ever heard do the bottom octave clean, let alone if you detune to B.

I've attached a chart that shows the volume displacement required for different bass frequencies to get different volumes. Work out how loud you want to play, and then read the number off the chart for 40Hz. Borrowing an SPL meter is a good idea.

Not knowing how loud you need to play, the size gigs you do, what drivers are available in Venezuela (and at what prices) or budget, I don't know what other drivers to suggest. A couple of ideas are,
4 x Delta 12LF
2 x Delta 15
The Beta's have weak motor assemblies and I don't think they'll supply the <i>snap</i> you're after. The Deltas are a bit better, the Pro ranges much better again, but more expensive.

Good advice from Brett. Just one small disagreement.

It should be pointed out that the chart that Brett provided is for sealed boxes only. When you port a design, you increase it's output between 3 and 4 times over the sealed design at the tuning frequency . With smaller enclosures it's 4 times or more output; with larger enclosures like yours, it leans more towards 3 times.

So that 100 cc of air you are moving at 42 Hz becomes between 300 and 400 cc of air at 42 Hz when you port the box.

Also, PA speakers are built with smaller linear excursions but have plenty of room outside the linear range. There will be sound compression and distortion, but at least extra is there when you have to "nail it".

You have better speakers than the ones you mentioned anyway, but I thought I would bring up the general principle. The chart is very useful as long as you multiply the volume by 3 or 4 for the tuning frequency. Above the tuning frequency, the benefit gets progressively less until there is little left an octave above the tuning frequency. That's okay-the greatest need for excursion is the lowest octave-precisely where the greatest benefit of the ported system lies.

kelticwizard said:

Just one small disagreement.

It should be pointed out that the chart that Brett provided is for sealed boxes only.

Click to expand...

No the chart is for the amount of air required to be moved at a certain frequency for a given SPL. It has nothing to do with the specific implementation of a given speaker. The chart applies to sealed or ported boxes, horns or monkeys waving fans.

So that 100 cc of air you are moving at 42 Hz becomes between 300 and 400 cc of air at 42 Hz when you port the box.

Click to expand...

Again, no. See above.

Also, PA speakers are built with smaller linear excursions but have plenty of room outside the linear range. There will be sound compression and distortion, but at least extra is there when you have to "nail it".

Click to expand...

For a bass when you want to slap, you need lots of clean transient ability, which translates to lots of clean excursion and displacement (in the lower ranges), and no compression or distortion. Compression and distortion are for guitarists.

The chart is very useful as long as you multiply the volume by 3 or 4 for the tuning frequency. Above the tuning frequency, the benefit gets progressively less until there is little left an octave above the tuning frequency. That's okay-the greatest need for excursion is the lowest octave-precisely where the greatest benefit of the ported system lies.

Click to expand...

First sentence, no. See above. The chart can be extrapolated to find the volume displacement required to give a certain SPL at any frequency.

Cheers

Brett said:

For a bass when you want to slap, you need lots of clean transient ability, which translates to lots of clean excursion and displacement (in the lower ranges), and no compression or distortion. Compression and distortion are for guitarists.

Click to expand...

I can only point out that most PA and bass speaker manufactuers do give the musician considerable excursion outside the linear range, and that most users avail themselves of it. If you can come up with a cabinet where your SPL needs are met without your cone going into the nonlinear range, then that is excellent. You have chosen your equipment well.

Brett said:

No the chart is for the amount of air required to be moved at a certain frequency for a given SPL. It has nothing to do with the specific implementation of a given speaker. The chart applies to sealed or ported boxes, horns or monkeys waving fans.

Click to expand...

Technically true, but misleading. The chart does indeed show the volumes of air that must be moved to achieve certain SPLs at certain frequencies, regardless enclosure type. However, it has to be pointed out that with the ported box, at the lowest frequencies, the speaker will not be the unit moving most of the air. The port will be moving the air. Comparatively speaking, the speaker's cone will be moving very little at the lowest frequencies, therefore the cone excursion requirements are much less for a speaker in a ported box to produce the same SPL's as a speaker in a closed box.

The following illustration shows two 10 inch speakers with equal midband SPL's, (87.8 dB@1Watt/1Meter) played at 100 watts each. The blue line is the ported speaker. The red line is a sealed speaker in a much larger enclosure. However, down to 30 Hz, the 3 dB down point for both, their responses are essentially identical.

Now, however, let us examine the cone excursion for these two 10 inch speakers putting out essentially equal output throughout their passband. Remember, the light blue line is the ported speaker, the red line id the the sealed box speaker. Remarkable difference, any way you look at it.

As you can see, at 30 Hz-the 3 dB down point for both speakers-the ported speaker only has to move between 2 and 3 mm, while the sealed box speaker-with the same SPL output as the ported-has to move about 14 mm.

For what it is worth, I think this simulation program, BoxModel by Bullock and White, is slightly optimistic as regards the excursion saving for the ported. This imaginary woofer is essentially a modified Peerless CSX 10", and the Peerless CSX 10" will give similar results to this when placed in a 2 cubic foot box and tuned to 30 Hz. I think the excursion saving at Fb is usually closer to fourfold as opposed to sixfold in a 2 cubic foot box as this simulation program shows. But let us not quibble-the point is illustrated.

The larger the enclosure is, the less the excursion saving, but it is still substantial. For a 5 cu ft plus box like luisma's, he can count on at least a threefold advantage, but he might get more. All this is assuming the box is well-made and sealed.

His speaker will only have to move one third as much as a sealed speaker to produce the same SPL at the tuned frequency of the box, therefore luisma should multiply his speaker's air moving capacity by three to see how loud it plays at the box tuning frequency. If the chart says that 1,000 cc of air must be moved to produce a certain SPL, a speaker in a ported box must only move 333 cc to produce that SPL-assuming the frequency is near the tuned frequency of the box.

I've used those Peerless drivers. They are very good, but they are not for PA work-they are home speakers. In fact, I think two might go a little lower in a 120 liter enclosure than 34 Hz.

The Xmax is 9 mm, and that is linear. The Peerless CSX 10" is one fine speaker, but nowhere near the sensitivity you need for PA work.

Luisma, brett, anybody else?

Why would you need an HF driver?

I have posted a similar question about using woofers for bass amplification (my bass player has no amplification as of now and I have some spare 12" woofers laying about). I see you recommend having tweeters. You would need them because...?

sangram said:

Luisma, brett, anybody else?

Why would you need an HF driver?

I have posted a similar question about using woofers for bass amplification (my bass player has no amplification as of now and I have some spare 12" woofers laying about). I see you recommend having tweeters. You would need them because...?

Click to expand...

Hi Sangram,

There are a couple of reasons for having an HF driver IMO. Firstly there is enough harmonic content to warrant the expense, <i>especially</i> if playing with a lot of slap, but still worth it otherwise. Most large drivers struggle to reach 1kHz cleanly (I'm describing how they sound, not measured FR) and beam like a spotlight at the top of their range. When playing live, or even jamming, without a clean HF response, the bass can become indistinct in the mix. Having the extended HF response there gives the option of EQing it down, if the sound desired is very woody like a classic acoustic upright would sound, or having it bright and extended like Stanley Clarke, Marcus Miller etc, and having it able to <i>snap</i> when thats what the player is playing.

There isn't a need to spend a huge amount of money on the HF driver; a Selenium 205 would make a good addition, and I bought mine recently for about $US12 each (+ flare). However, the quality of the HF driver should match the quality of the other drivers.

HTH
Cheers

Wiz,

Thanks for putting all the effort into that series of posts explaining how porting works. I already knew.

The volume displacement chart I posted, does not differentiate between method of generation, so it does not apply directly to a sealed box as you stated in your first post. In the band around resonance, the combined total of the port and driver will be the measure of performance in a ported box, no question. However, there is a decided difference in tonality between what comes directly from the driver, and what comes from the port. They don't sound alike and the tone will change a lot in that bottom octave. I've found this in almost every domestic ported box I've ever heard, that's why I won't own one any more.

From my experience with PA systems, a pair of 12" drivers with a Vd of 84cc, irrespective of what a port may add, will not be enough to overcome a drumkit in the nearfield. You need to move a LOT of air and clean.

Cheers

luisma1972 said:

I've made a quick calculation using 2 peerless CSX 257H drivers in a 120 l enclosure. The problem with this setup is the eficiency, I will need more power to equal the spl that the DELTA 12 can achieve, and of course the HF responce begin to drop earlier in the spectrum. Which other drivers shoud I take into account?

Click to expand...

Luis,
Hi Fi drivers are as weak as ____. Stick with Pro gear, because as you pump the domestic units with power to try to get the same SPLs as the Pro drivers, you'll cook them. You want efficiency, and lots of air moving.

I'll look at the catalogues again and think some more on the subject of particular drivers.

Reply

If your a bass player,and your after deep bass,rather than just slap sounds.I suggest a 3 way consisting of;

I driver i use is the Eminence Beta 15, rated 350w rms,
frequency range 35hz-4khz, 8 0hm,average sensitivity 1w at 1m 98 db, magnet weight 38 0z,2 inch voice coil, xmax 4mm,x mech
36.45mm,VD [peak diapharm displacement volume] 327cc.

Eminence Guitar Legend 12 for slap and mid sounds rated 100w rms.
And a Eminence APT50 horn rated 85 w rms.

Use these three with a suitable crossover,such as the Eminence 3 way 18db/0ctave crossover.

For proper nice warm pure deep bass for bass guitar,i prefer The Eminence Sigma pro 18 inch,rated 650w rms,driven by several class A valves.I cost a lot,but sounds fantastic,and you have to get the cabinet volume and port size exactly right too,otherwise it sounds boomy,lacking any weight.

Thankx. Well and clearly put.

That helps a lot. I'll be looking at a single compression driver with 2 12" woofer in each cab. For close to free, that's a lot of speaker. My bassist should be happier.

However, the drivers are not very efficient, about 90 dB or so (guesstimate). They also need about 30WRMS to get going.

At about 70 watts, they start to sound good. My 100 w/ch amp cannot keep up, not even close. I may have to actually buy a head later.

Brett said:

Hi Sangram,

There are a couple of reasons for having an HF driver IMO. Firstly there is enough harmonic content to warrant the expense, <i>especially</i> if playing with a lot of slap, but still worth it otherwise. Most large drivers struggle to reach 1kHz cleanly (I'm describing how they sound, not measured FR) and beam like a spotlight at the top of their range. When playing live, or even jamming, without a clean HF response, the bass can become indistinct in the mix. Having the extended HF response there gives the option of EQing it down, if the sound desired is very woody like a classic acoustic upright would sound, or having it bright and extended like Stanley Clarke, Marcus Miller etc, and having it able to <i>snap</i> when thats what the player is playing.

There isn't a need to spend a huge amount of money on the HF driver; a Selenium 205 would make a good addition, and I bought mine recently for about $US12 each (+ flare). However, the quality of the HF driver should match the quality of the other drivers.

HTH
Cheers

Click to expand...

Hi Folks, thought I might stick my oar in here for a bit of fun...

In my experience, most bass cabs for stage use do not go that low, usually they are sealed boxes with high Q, rolling off at about 50 Hz. This gives perceived loudness, due to the natural response of the human auditory system "filling in" the missing frequencies.

The reason commercial boxes don't go low is for sound practical reasons, (pun intended ). Firstly, the power needed to get decent sound output at low frequencies is large, and would require a huge reliable amp. Bass players also in general prefer a louder amp, and this is easily achievable by cutting out low end response, and most would buy an amp that appears louder, rather than one that goes lower.

Secondly, all that low frequency energy is a menace on stage for a FOH/Monitor engineer, it is much more preferable to add the trouser flapping frequencies with the main PA via a DI out from the bass or amp.

So, even though Brett and Keltic Wizard have some good points, bass extension is not particularly relevent to this application, IMHO.

For speaker recommendations, if you can easily get Eminence, have a look at the Omega Pro 15", it is relatively cheap, is reliable, and has good power handing. Oh, and it sounds quite good as well! I will do some more research over the weekend for other drivers as I am a bit out of date

bass amplification....

Hi you guys,

I decided to throw some thoughts in, I also play bass (occasionally at least ). I run the signal through a Nobels Compressor pedal directly into the mixing desk.
My speakers are all diy , the rig consists of a crest CA6 amp (2 x 400 W RMS @ 8 Ohms), two 15" subs with Eminence Kappa 15LF (another pair is currently under construction ) and a pair of two ways with noname 12" and Motorola Piezos.
I practise together with my brother (he plays drums), and boy oh boy, I make the whole place shake.......

If you play gigs at small venues such solution would fit quite well. I can use my system either for bass exclusively or run addittional stuff through it, or just play some CD's at an annoyingly loud volume.

Also, this way you can first go for brute power, and later on e.g. buy a good preamp etc....

hope this helps you.