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Author Topic: Lab Sub handling  (Read 19196 times)

Benjamin Goulart

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Re: Lab Sub handling
« Reply #60 on: December 26, 2013, 07:10:34 pm »

Since you have multiple cabinets and multiple amplifiers-why not do the experiment yourself?

There are advantages and disadvantages to both series and parallel wiring.  It depends on particular situations.

Since this is for YOUR use-then YOU need to decide.

But no, you will not do any damage to anything by putting them in series-assuming everything is run in the linear range.

Also remember that when you bridge you double the voltage-which is 4x the power (into the same impedance.

You also need aware of what "peak" may mean-especially in the amp settings.  In many amps the PEAK- is 1.414 times the RMS of the maximum voltage waveform.

Lets look at some simple math.  The lab12 is rated for 400 watts and is 4 ohms.  Inside the labhorn it is likely higher-but lets ignore that for now.

That is 40V.  So the "peak" or max voltage would be double that, or 80V.  But if you wanted to set the "peak" on an amp like a lab gruppen-Crown-Powersoft etc you would enter 800x1.414 or 113volts.

But if you measure the voltage (with a typical voltmeter) it would read 80V NOT 113 volts.  The peak on an oscope would read 113V.

So when discussing numbers-it is important to be specific what is meant by "peak".  Is it "peak" or "max".  THey can be very different.

I know it's not going to hurt anything as long as the amp's still set to 42Vp limit per Labhorn in the DSP section, but I thought I'd read somewhere that sub drivers in general will behave different tonally based on the impedance they're wired.  I assumed the amp will have an easier time, but then again since it's also lowering the available watts, maybe it wouldn't make any difference.

I sort of don't want to unseal the other amp.  I was thinking in terms of still using just the one, either rewiring each sub internally to series and using the amp in stereo, or leaving the subs internally wired to parallel and linking their cables in series with an adapter of some sort to utilize the single amp in bridge mode.  I already have adapters for the bridge pin wiring, and another adapter could be done up to link them, or get one of those little boxes.

So I guess the real question is a two part:

1) will the Labhorns sound different (tonally, dynamically, transients, etc) wired as 12ohms instead of 3ohms, assuming any given amp in question can get them the same real volume in either case?

2) will a class D amp have an easier time with 12ohms than 3ohms using the same model & quantity of drivers but in a different arrangement, or is it completely moot since the available watts is decreased anyway?

I suppose I could also make it easier on the power supplies inside by only using one amp for each sub, but I still would rather keep the extra one sealed until I either have an emergency or decide I'm definitely not selling/returning it.  The bridge adapters were made for that, but considering the Labhorns are already wired parallel, the amps are not supposed to go below 4ohms in bridge, and it's way more power than needed, I haven't bothered. 

And I think we've already determined that the conservative linear performance cap for the Labhorn was about 45V peak assuming either no EQing or using live production or a band, 85V peak with some EQing with normal mastered music or babysitting, and about 65V peak from a conservative thermal standpoint.  77Vp is the theoretical xlim mechanical damage zone for a 34-36hz crazy peak without any HPF, EQ, or limiter.  45V peak can already get plenty loud to keep up with my tops and allow EQing.  That's not even really with the subs coupled, but rather in separate corners, and my third modified reflex powered sub totally turned off rather than adding additional midbass punch. 

So I'm comfortable with just 45V peak limiting kept on per Labhorn regardless, just curious about impedance, bridging, and power supply performance as other variables affecting the reproduction of continuous dubstep style tones, since I don't need to worry about mechanically or thermally damaging anything.  I'm mostly wondering if I'm shortchanging the continuous tone capability of the amp by presenting a 2-3ohm load to it instead of 6 or 12ohms.
« Last Edit: December 26, 2013, 07:16:43 pm by Benjamin Goulart »
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Benjamin Goulart

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Re: Lab Sub handling
« Reply #61 on: December 26, 2013, 07:31:35 pm »

Is the dB a given driver produces based on the voltage or the watts?

Would a given arrangement of drivers wired as 12ohms instead of 3ohms require nearly 2X the volts to reach the same volume?
« Last Edit: December 26, 2013, 07:47:08 pm by Benjamin Goulart »
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Ivan Beaver

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Re: Lab Sub handling
« Reply #62 on: December 26, 2013, 07:55:55 pm »

I know it's not going to hurt anything as long as the amp's still set to 42Vp limit per Labhorn in the DSP section, but I thought I'd read somewhere that sub drivers in general will behave different tonally based on the impedance they're wired.  I assumed the amp will have an easier time, but then again since it's also lowering the available watts, maybe it wouldn't make any difference.

I sort of don't want to unseal the other amp.  I was thinking in terms of still using just the one, either rewiring each sub internally to series and using the amp in stereo, or leaving the subs internally wired to parallel and linking their cables in series with an adapter of some sort to utilize the single amp in bridge mode.  I already have adapters for the bridge pin wiring, and another adapter could be done up to link them, or get one of those little boxes.

So I guess the real question is a two part:

1) will the Labhorns sound different (tonally, dynamically, transients, etc) wired as 12ohms instead of 3ohms, assuming any given amp in question can get them the same real volume in either case?

2) will a class D amp have an easier time with 12ohms than 3ohms using the same model & quantity of drivers but in a different arrangement, or is it completely moot since the available watts is decreased anyway?

I suppose I could also make it easier on the power supplies inside by only using one amp for each sub, but I still would rather keep the extra one sealed until I either have an emergency or decide I'm definitely not selling/returning it.  The bridge adapters were made for that, but considering the Labhorns are already wired parallel, the amps are not supposed to go below 4ohms in bridge, and it's way more power than needed, I haven't bothered. 

And I think we've already determined that the conservative linear performance cap for the Labhorn was about 45V peak assuming either no EQing or using live production or a band, 85V peak with some EQing with normal mastered music or babysitting, and about 65V peak from a conservative thermal standpoint.  77Vp is the theoretical xlim mechanical damage zone for a 34-36hz crazy peak without any HPF, EQ, or limiter.  45V peak can already get plenty loud to keep up with my tops and allow EQing.  That's not even really with the subs coupled, but rather in separate corners, and my third modified reflex powered sub totally turned off rather than adding additional midbass punch. 

So I'm comfortable with just 45V peak limiting kept on per Labhorn regardless, just curious about impedance, bridging, and power supply performance as other variables affecting the reproduction of continuous dubstep style tones, since I don't need to worry about mechanically or thermally damaging anything.  I'm mostly wondering if I'm shortchanging the continuous tone capability of the amp by presenting a 2-3ohm load to it instead of 6 or 12ohms.
As I said there are MANY factors involved-NOT just one or two.

For example most modern amplifiers cannot produce full output for very long.  Typically it is on the order of 0.08 seconds or less.  Longer than that and the power drops-often by 6dB or 1/4 power.  Some amps are much less than 0.08 sec.  What about your amps?  Amplifiers can deliver power into higher impedances for longer periods of time.

When you put speakers in series the damping factor goes up by a factor of 4 (due to the higher impedance as oppossed to them being in parallel).

With a higher load impedance there is less loss across the cable and the damping factor again goes up.

When an amp is in bridge mode the damping factor drops in half-due to the 2 output sections being in series.

However the "control" as seen from each of the speakers is not as high as it would be with a single speaker-since the other speaker is in series-causing a  much higher impedance or less control from the amplifier.

So as you can see there are pluses and minuses.  YOU need to decide what is most important to you.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

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Re: Lab Sub handling
« Reply #62 on: December 26, 2013, 07:55:55 pm »


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