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Double Bass Arnopol 8 Cabinet - A Winner!

#121
I've had my Crazy 8 for a month now and I'm blown away by how great it sounds and how light it is. My 8 has a tweeter with an on/off switch and a pole mount. I'm using it in a quartet setting (sax/piano/double-bass/drums), playing restaurants and small clubs. Driven by an EA Doubler, it gets as loud as I could possibly imagine needing it to be. In addition, this rig disappears into whichever small space you're forced to place it. Everyone I've play with has commented about how clear, present, and natural the bass sounds. I can honestly say that I've never been happier with my amplified bass sound. Thanks, Mike. Glad I found and followed this thread.

For reference purposes, in the past I've used an Acoustic Image Contra, Iamp800 into a VL-208, Iamp800 into a Wizzy M-line 12.
 
#124
geoffbassist said:
MLysh , do you prefer the tweeter on?

Thanks Geoff
Click to expand...

There is a very subtle difference between on and off. So far, I've preferred the tweeter on. I hear just a hint more texture and presence with it on. It sounds a tad thicker and deeper with it off. That's great in my living room, but seems to get a little lost in the drums on the gigs I've played, so far. I bet it would fit right in on a drummer-less gig or in a duo situation. As always, so much depends on the room, the placement, etc., that it's really tough to generalize.
 
#125
When I got my Crazy8 I played CDs through it for a day or so to break in the driver. Needless to say, the sonic quality was fabulous - much better than the existing 8" mains. So one thing lead to another and Mike made me two more Crazy8s for new mains in the home studio. The sound is remarkable. I had these built with stackable plastic corners so the mains also can double as a "Crazy88" stack. Bought a pair of modified "L" connectors to convert the quarter inch jacks into Speakon. Takes a couple of seconds to grab the pair off their wall platforms for gig duty. They include pole mounts in case I want to use them with a PA at a small gig venue. The last photo shows stack next to a LDS 12/6 cab and my bass.

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#127
Still working on it---as of right now I'm not really hopeful. Faital is talking about having 4 and/or 16 ohms available---but they aren't right now. I'll keep y'all posted as to news. I can however put in a switch to change from 4 to 16 ohms. That way you'd have an 8 ohm load when combining two cabs. If you had a good 400 watts at 8 to drive them you'd be all set. Or a 4 ohm single cab.
 
#128
Mike Arnopol said:
... I can however put in a switch to change from 4 to 16 ohms.
Click to expand...
Do I understand correctly that, by flipping a switch, you can change the impedance of your current design from 4 to 16 ohms? Other than inserting a dummy load, how is that accomplished?
 
#132
I need help understanding the relationship between impedance and distribution of amplifier power.

I own an 8 Ohm Crazy8, and I'd like to create a three-driver mini-stack by adding a Crazy88. If identical drivers are used in both cabs, the Crazy88 would be 4 Ohms, the combined impedance of the load seen by the amp would be 2.67 Ohms, and power would be evenly distributed among all three drivers.

What would power distribution look like if I used an 8 Ohm Crazy8 and a 16 Ohm Crazy88? :confused:

My concern is that a disproportionate amount of power would go to the Crazy8, risking damage.

If one of you would be so kind as to walk me through the calculations, I'd appreciate it! :)
 
#133
Jazzdogg said:
I need help understanding the relationship between impedance and distribution of amplifier power.

I own an 8 Ohm Crazy8, and I'd like to create a three-driver mini-stack by adding a Crazy88. If identical drivers are used in both cabs, the Crazy88 would be 4 Ohms, the combined impedance of the load seen by the amp would be 2.67 Ohms, and power would be evenly distributed among all three drivers.

What would power distribution look like if I used an 8 Ohm Crazy8 and a 16 Ohm Crazy88? :confused:

My concern is that a disproportionate amount of power would go to the Crazy8, risking damage.

If one of you would be so kind as to walk me through the calculations, I'd appreciate it! :)
Click to expand...

You're correct -- the Crazy8 will be expected to handle twice the power of the 88 in that scenario, i.e. 4 times the power of each driver in the dual cabinet. The combined impedance will be 5.33 ohms, so safe for most amps, but a bit of a waste of the 88. Better to have a single 88 or a pair of 8s than the second setup you describe. For an amp stable to 2 ohms, though, the first rig sounds like a winner. :)
 
#134
As long as your load does not go under the minimum output impedance no harm to the amplifier.
As long as a single speaker is not overloaded by the amp (like in the normal one amp - one speaker) it wouldn't by adding more speakers (but the amp might, see above). The same current will flow through this speaker, just an additional current through the other.

BUT, if you use the same speaker impedance, one single speaker or two in parallel and one box with both (or more) speakers in series and wire these boxes in parallel (this is the normal case), then the higher impedance box (serial connection) produces much less volume but could be loaded with a higher wattage than the single or parallel wired box. Unfortunately the single or parallel box cannot atand the additional wattage, so you cannot make use of the additional wattage of the serially wired box if you don't want to blow the other speakers.

So it doesn't make sense to mix a 4 Ohm and a 16 Ohm box. You won't get much volume from the 16 Ohm. It might make some sense if you have a tweeter or midrange driver with a horn, since these usually produce more pressure and might be damped this way a bit. But then you also need a frequency divider. So, even this is not a good idea.

Better get 4 or 8 16 Ohms Crazy88 and a really powerful amp, connect them in series and you blow the whole band away, yeah! (Don't forget to use a security belt and earplugs yourself!)
 
#136
Hi Chris,

did you try wiggling the strings while looking at both (all) membranes? They should move together in the same direction. If not you have a phase problem and one (or more) moving in the opposite direction need a polarity change (cross change the two cables at the speaker inside the box or at the terminal).
If you have a tweeter too, you need to try a bit more to find out if the exchange at the speaker or the terminal (which chnges the phase of the tweeter too).
In general the hot phase on speakers terminal is marked red, if it was correctly marked at the factory you can use this as orientation. (But if something is strange don't take this for granted.)
 
#138
Jazzdogg said:
I need help understanding the relationship between impedance and distribution of amplifier power.

I own an 8 Ohm Crazy8, and I'd like to create a three-driver mini-stack by adding a Crazy88. If identical drivers are used in both cabs, the Crazy88 would be 4 Ohms, the combined impedance of the load seen by the amp would be 2.67 Ohms, and power would be evenly distributed among all three drivers.

What would power distribution look like if I used an 8 Ohm Crazy8 and a 16 Ohm Crazy88? :confused:

My concern is that a disproportionate amount of power would go to the Crazy8, risking damage.

If one of you would be so kind as to walk me through the calculations, I'd appreciate it! :)
Click to expand...

Here's what it would look like. You would have an 8-ohm load (Crazy 8) in parallel with a 16-ohm load (Crazy 88 with drivers wired in series). With a voltage applied to that circuit, half the current would flow through the 16-ohm Crazy 88 than would flow through the 8-ohm Crazy 8. Correspondingly, half the power would be developed across the Crazy 88 than would be developed across the Crazy 8.

So, assuming linearity and equal sensitivity of the two cabs, the acoustic output of the Crazy 88 would be 3-dB down compared to that of the Crazy 8.

Now, let's look at each driver within the Crazy 88. Because it would be wired in series and because each driver has the same impedance, then the current flowing through each driver would be the same with each driver contributing equal shares of the "half-power" through the box. That is, the power developed across each driver in the Crazy 88 would be 1/4 of that developed across the Crazy 8.

Here are the calculations. Let's assume a 1-volt input to the circuit. We'll also assume that Ohms law (V=IR) applies and we'll eschew the reactive AC components.

What is the current across the Crazy 8?
It is 1/8, or 0.125 amps (I=V/R).
What is the power developed across the Crazy 8?
It is 0.125 watts (I2​R or V2​/R).
What is the current across the Crazy 88?
It is 1/16 or 0.0625 amps.
What is the power developed across the Crazy 88?
It is 0.0625 watts.
What is the power developed across each driver in the Crazy 88?
It is 0.0625 2​*8=0.03125 watts (I2​R).
So, you see, the power developed across each driver in the Crazy 88 is 1/4 of that developed by the single driver in the Crazy 8.
 
#139
As to the 2-ohm sound question: I've run two Wizzy m-line 12's with an Iamp 800 in an eleven piece wedding band and it sounded great, but that was with an electric bass. Luckily, I haven't had to play that loud of a gig in quite a while. Will we ever be able to turn down?
 
#140
DoubleMIDI said:
As long as your load does not go under the minimum output impedance no harm to the amplifier.
Click to expand...

Keep in mind that the "nominal" impedance rating is just that. Impedance, by definition, varies with frequency. Depending on the design, the impedance may drop substantially below 2 ohms.


DoubleMIDI said:
Hi Chris,

did you try wiggling the strings while looking at both (all) membranes?
Click to expand...

If you can wiggle the strings and see the cones move, then that's a sure sign that the system is happy to pass along power-robbing, potentially driver-damaging infrasonics. This is why we have high-pass filters. :)
 

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