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Double Bass Doubler at 2?

tyb507

tyb507

Sep 17, 2004
715
216
Burlington, Vermont
swalesong.com
#1
So I remember seeing somewhere on here that the Doubler is 2Ω compatible, and I just got a smoking deal on a new one.

The specs in the paperwork specify 8Ω and 4Ω, but not 2Ω. Gollihur's site has this in the specs:

"Power Output: 550 watts @ 4 or 2 ohms; 310 watts @ 8 ohms"

Are there different versions? Or are people just running them at 2Ω and it can handle it? Part of why i wanted it was to be able to run at 2Ω. So, what's the story? I'd love to run my 4x8 8Ω and 2x8 4Ω cabs together (2.6Ω, right?), but I don't want to trash my Doubler!
 
#4
tyb507 said:
Anybody? Little help? Arnopol? I know there are some Doubler-users out there!
Click to expand...

Tyb50,

Here's the specs from the Micro/Doubler Manual that Euphonic Audio, provides with these amps.

"Power: 550 watts RMS@4 ohms, 550 wattsRMS@2ohms,350wattsRMS@8ohms"

If you wan't to download the manual you can do it by clicking on the link below.

[Invalid or Expired Link Removed]

Since you purchased the unit second hand, you may not have received one. Using a pair of two 4 ohm cabinets would necessitate having
an amplifier that will operate at two ohms. Digital Amps that operate at two ohms is a relatively new development in bass amplifier design.
It will be interesting to see if this trend pans out.

Ric
 
#7
tornadobass said:
I've used my Micro with a pair of wizzy cabs (total 2 ohms) quite a few times with no problem. With a pair of Wizzy 12s, the master volume rarely goes past noon in outdoor gigs without pa support.
Click to expand...

Tornado Bass,
I'd be interested in knowing if the EA Micro runs puts off more heat when it's running at 2 ohms. Since I don't know how it's thermal protection is configured. I was wondering if the cooling fan cycles more often at the 2 home load, but if the fan runs continuously then, that wouldn't be a reliable way to evaluate the heat dispersion. Just curious.

Ric
 
#12
Usually, with solid-state amps, as the nominal impedance of the load (the speaker cab) drops, the power output capability of the amp increases because the impedance of the load approaches the internal impedance of the power amp (which is very low). That is, as the impedance of the load decreases, the load comes closer to matching the impedance of the amp, which would be the point of maximum power transfer.
What limits the continual increase in power as impedance is dropped is the amp's current capability. Let's say that you want to produce 100 watts into 8 ohms. Considering only the resistive (and not the reactive) component of impedance, the current required would be:

100 = I2​R, where R = 4 ohms. I (the current) would be 5.0 amps.

Drop R to 2 ohms and the current required would be 7.1 amps.

This can't go on forever because, eventually, the impedance will be dropped to a point where the current required for a given power output will be more than the amp can produce. The fact that the rated power of the Doubler is the same into 4 ohms and 2 ohms likely reflects the amp's current limitations.

As for heat, yes, you can expect the amp to run hotter when producing the exact same power across a 2-ohm, vs. a 4-ohm load. That's because more current will be flowing through the (essentially constant impedance) devices within the amp, resulting in greater heat.

Finally, keep in mind that when you include the reactive component of impedance and account for the fact that the impedance of a speaker cab is a function of frequency, a load with a 2-ohm nominal impedance may, depending on the design of the cabinet(s), dip substantially below 2 ohms and stress the power amp. Based on the experiences of those who've posted above, this is, apparently, not an issue with the typical cabs used.
 
#14
Adagio said:
Even if the amp is rated the same power at 2 and 4ohms, wouldn't you get more perceived volume with 2 cabs just because you move more air?
Click to expand...

Adagio,
I would think that to be true. When my only amp was a Walter Woods MI-100-8, I used two orphaned Ampeg B15N Cabinets with upgraded speakers, and that definitely gave me a little more power, but with the additional volume came the increased load on the power amp from dropping from 8 ohms to 4. As a result the amp produced more heat.
I tried it several other times with my Walter Woods MI-400-8 and several different parings of speakers, Bose 802's, Flite Sound 2x8's and eventually EA VL 108's. From all these experiments, I discovered that I prefer a slightly bigger cabinet, to using pairs of cabinets. It's not as portable but it tends to feedback less with my bass and pickup. I finally rested on the Audiokinesis TC 112.

Ric
 
#16
Adagio said:
Even if the amp is rated the same power at 2 and 4ohms, wouldn't you get more perceived volume with 2 cabs just because you move more air?
Click to expand...

Nope. Power is power. If you could keep adding cabs and move more and more air, all with constant power, then our energy crisis would be solved! :) Now, if you are not at the limits of the amp, then, all other things being equal, adding a cabinet will cause you to draw more power. The increased sound-pressure level that results will typically translate to greater perceived loudness. The Doubler will put out 550 watts into 4 ohms and 550 watts into 2 ohms. Assuming two identical cabinets, each of which can handle all 550 watts, you will get the same sound-pressure level from the two cabs as you will get from a single cab. Now, you may prefer two cabs because you can direct the energy differently, but that's another matter.

Ric Vice said:
Adagio,
I would think that to be true. When my only amp was a Walter Woods MI-100-8, I used two orphaned Ampeg B15N Cabinets with upgraded speakers, and that definitely gave me a little more power, but with the additional volume came the increased load on the power amp from dropping from 8 ohms to 4.
Click to expand...

When you added that extra cabinet, you developed more power.
 
#18
Mike Dimin said:
If you add a second cabinet, for example a second wizzy 10 to a doubler and Wizzy 10, you will increase your volume by 3dB. Not much but there will be a minimal increase in volume
Click to expand...

Yes, the sound-pressure level will be increased by 3 dB (assuming independence). That'll be a minimal change in loudness and "volume" which are psychological quantities. Of course, that same 3 dB can be achieved by turning up the gain with a single cabinet. Again, when you add the second cab, you are drawing (and producing) twice the power.
 
#19
drurb said:
Yes, the sound-pressure level will be increased by 3 dB (assuming independence). That'll be a minimal change in loudness and "volume" which are psychological quantities. Of course, that same 3 dB can be achieved by turning up the gain with a single cabinet. Again, when you add the second cab, you are drawing (and producing) twice the power.
Click to expand...

You do also get the psychological feeling of "pushing more air" Some players need that. It is why Hugh McDonald loves an 8x10 on stage - he wants to feel the push.
 
#20
Mike Dimin said:
You do also get the psychological feeling of "pushing more air" Some players need that. It is why Hugh McDonald loves an 8x10 on stage - he wants to feel the push.
Click to expand...

I think that phenomenon is really about dispersion. The additional cab or drivers spread the constant power over a broader area. I agree that it's a very real attribute. By the way, here's an old post of mine re loudness.
 

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