watts it all about Ohm confused!

[dove]

Hi

 

I have an EA doubler and a 4ohm wizzy 12 m-line cab.  Amp rated at 550 watts (@4ohm) and cab at 200 watts. I blend a full circle and a Krivo mag p/u.

Happy with sound but need more volume. I can run the EA double with the peak lights blinking and master at full volume and the cab seems to handle this fine( which is a bit confusing - amp 550 watts, cab 200 watts?) but just need more volume for bigger gigs. If I added a second 4 Ohm cab like the Eden EX112 1x12" Compact Bass Cab, 4 Ohm that would bring it down to 2 Ohms. I have mocked this up with 2x P,JB 5" 50watts speakers wired at 4 ohms but it doesn't make alot of difference volume-wise and I see from the EA specs that the amp is still only 550 watts at 2ohms. My question, I guess, is will adding the 300w watt eden to the 200-watt wizzy give 500 watts and hence more volume? Or how do I get more volume? many thanks

[gjones]

Two 12 inch cabs will always sound significantly louder than one. It's to do with the surface area of the speakers. If the cabs are both 4 ohms, and they're attached in parallel,  then the combined impedance will be 2 ohms. Which should be fine if your Eden is designed to work with that load.

[warwickhunt]

There's no replacement for displacement... the more speakers the better, even if you are getting (in theory) exactly the same wattage/power.

[Owen]

In almost everything, less is more.

[Owen]

But when it comes to volume, as Yngwie says, more (speakers) is more.

 

 

[Downunderwonder]

Back up the bus.

 

You said the amp is rated as 550w 4 ohm. That usually means you can only hook up one 4 ohm cab or one 8 ohm cab, or two 8 ohm cabs.

 

With parallel cabs 4 ohms plus 4 ohms makes 2 ohms which is an illegal load unless the amp comes with a 2 ohm rating.

 

Less impedance with the same voltage lets more power come out of the amp. Too little impedance makes too much power and the amp cooks itself with its own enthusiasm.

 

On paper you should be toasting your 4 ohm 12" cab. I guess the amp is really not all that powerful.

 

There really is no comparison between 2x5" cab and anything else that calls itself a bass cab. Impedance is the last thing you need to consider.

 

To make significant gains in volume the easiest route would be get a more efficient 4 ohm cab/ pair of 8 ohm cabs/ loud 8 ohm cab.

 

You might need a new amp but leave that for another day.

 

 

[NickA]

How loud do you need ot be?  What are you playing and with whom?  My 400W PJB rig can be heard over a full symphony orchestra (Christmas Symphonic Rock concert !) and is fine with a drummer, electric gurarist, amplified keyboard and a couple of saxes.

 

Adding more cabs won't increae the volume as the amp wil run out of capability to deliver the current; EA don't seem to support 2Ohm loads so you might damage the amp by trying.

 

Largely I'd agree with downunderwonder, but if you really wnat to be louder, it probably does need a bigger amp - cab efficiency will yield a bit, but it's percentages not whole numbers.

 

NB: the fact that you can manage to drive a 200W 4Ohm cab with a 550W amp at full blast means that the cab manufacturer was conservative in their ratings!  Remember that cab ratings are usually based on a continuous sine wave output and the bass gives out a highly variable signal level which might cause the amp output to peak at 550W but with a much lower average power ... hence you can get away with it!

[chyc]

This doesn't sound right. The EA Doubler is a decent amp, and a 12" EA Wizzy 12M has a sensitivity of 103dB. Given you're playing an upright bass I would guess you're not playing thrash metal, so I'm going to go out on a limb and say that you probably could be loud enough without spending anything extra: I'd be blowing barn doors off with your setup.

 

A few things for you to check:

 

1. When you blend your two pickups, have you ensured they're in phase? I don't think this has ever happened to me to a significant extent but when blending two sources each one could be cancelling each other out. One way to test would be to dispense with one for a bit and seeing if that improves things. As an aside how loud does your band play? Of course if you like the blended sound of the two pickups then I can't argue with that, but if it's just to tame feedback I've never ever had problems with using just a Full Circle.
2. Are you using a HPF? You absolutely definitely want to be using this. The double bass booms so removing all the bass frequencies paradoxically is what you want to do. I don't know which EA Doubler you have but the manual I'm looking at seems to have a jumper setting for an 80Hz HPF. That's what you want, and don't let any electric bassist tell you otherwise

Again I stress I'm saying this without knowing what type of music you play, but I will say that I've played many jazz big band gigs with 350W into one 10" speaker. Sometimes in the absolute worst possible rooms I was left wanting, but not often and I know more about EQ now so perhaps that was down to my naivety. Your setup is on paper (I've never tried it) more performant than what I've used for many years.

[Downunderwonder]

3 hours ago, NickA said:

cab efficiency will yield a bit, but it's percentages not whole numbers.

Jeebers. While I broadly agree with the rest, this is way off base.

 

Pump up a genuine 4ohm  200w cab with a 500w amp and you're probably going to the whole 200w into it if you're trying.

 

Even if it's a 400w cab.

 

So the solution is not going to be more power.

 

If we're talking in general, the solution to more volume is almost always a straight line to more cab, not more power.

 

Two efficient 8ohm cabs will walk all over one inefficient 4 ohm cab every single time. 

 

It takes a DOUBLING of power, AND the ability to handle all that power, to make up for a 3dB sensitivity deficit.

 

You can pick up an extra 3dB sensitivity from adding a second cab. You get something along the way to another 3dB if the same amp makes more power into 4 ohms instead of 8 ohm. Those are whole numbers.

[NickA]

5 hours ago, Downunderwonder said:

It takes a DOUBLING of power, AND the ability to handle all that power, to make up for a 3dB sensitivity deficit.

Totally true! I didn't mean to suggest a massive increase in volume simply by adding a bigger amp, jut that a bigger amp might be needed to fully drive bigger speakers!  Though the man is right that more cabbage (to make better use of the wattage) may do the trick. 

 

When you overdrive a cab, it will distort - too much current going trhough the speaker coil will push the cone beyond it's linear operating point (ie just runs out of room to move) it won't just be quieter than expected but will sound bad too ... though it's the initial "thump" at the start of the note that will get attenuated and bass notes will suffer more than higher frequencies (bass notes move the cones more).  However rating in watts is a poor measure of transient handling ability .. so not all 200W cabs are going to be equal.

 

Two 8ohm 200W cabs in parallel will provide a lot more headroom and a better sound than 1x 4 Ohm 200W cab and two 200W 4Ohm cabs in parallel will provide nothing extra (the amp will overload).

But also totally true is that a 550W into 4ohm EA doubler and a decent 200W 12" cab really ought to be loud enough for an upright; (my 150W PJB flightcase is NOT lound enough whereas the full 400W flightcase + PB300 is as loud as I've ever needed). 

 

Something amiss in the signal path?  How ARE those pickups being blended?

[Downunderwonder]

5 minutes ago, NickA said:

Two 8ohm 200W cabs in parallel will provide a lot more headroom and a better sound than 1x 4 Ohm 200W cab and two 200W 4Ohm cabs in parallel will provide nothing extra (the amp will overload).

Generally you'd be right but you could find some little 8 ohm drivers in two little cabs and a big old 4 ohm 15 cab and you'd be wrong. It pays to be specific on generalization.

[Downunderwonder]

@dove All figured out yet? Techspeak that couldn't be substituted easily can be explained if you are still confused. 

[dove]

Many thanks for everyone's input, most helpful. It sounds like my best option is 2x efficient 8ohm cabs. Genre wise I play in a number of bands which is kind of the issue as they all have different sound requirements. Duos and trios all is fine. But I also play in a 6 piece ska/reggae band and and 9 piece Highlife band. All in venues from toilets to large 500 capacity venues. The Ea Double does go down to 2ohms but you still only get 550 watts as per 4 ohms. I blend the pickups via the doubler which has variable phase reverse and HPF and I also run the full circle through a fishman platinum pro which also has phase reverse and HPF so I think I have that covered. What I do know is that whenever I go down the rabbit hole of getting my sound only louder the best improvement I can make is to practice more!!!