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Author Topic: amp  (Read 6939 times)

Bob Kidd

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Re: amp
« Reply #10 on: July 30, 2014, 11:10:01 AM »

The bigger issue is how much voltage GAIN each amp has.  If you match gains, the "smaller" amp will clip before the larger amp, but until that point is reached the speakers will receive the same VOLTAGE.

The 5050a has a gain of 36dB (64x) and the PL340 is a different beast, but has selectable input levels, including a 1.2v input sensitivity setting that yields a 36.4 dB voltage gain.  Use this setting on the 340.

Excellent, thanks Tim! So it comes down to making a call as to whether it makes sense spending extra to rent another 5050 or going with what I have in the 5050 and 340.
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Alex Rigodanzo

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Re: amp
« Reply #11 on: July 30, 2014, 06:31:25 PM »

The bigger issue is how much voltage GAIN each amp has.  If you match gains, the "smaller" amp will clip before the larger amp, but until that point is reached the speakers will receive the same VOLTAGE.

The 5050a has a gain of 36dB (64x) and the PL340 is a different beast, but has selectable input levels, including a 1.2v input sensitivity setting that yields a 36.4 dB voltage gain.  Use this setting on the 340.

This is true, but the op is looking for max headroom.  With the smaller amp clipping sooner, you're out of headroom.  You might as well just run all 4 off the 5050.  You'll have about the same watts/cab at clipping.  Another 5050 will provide a lot more headroom.
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Tim McCulloch

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Re: amp
« Reply #12 on: July 30, 2014, 06:44:43 PM »

This is true, but the op is looking for max headroom.  With the smaller amp clipping sooner, you're out of headroom.  You might as well just run all 4 off the 5050.  You'll have about the same watts/cab at clipping.  Another 5050 will provide a lot more headroom.

The difference in "headroom" is less than 2dB.  He can tickle the clip lights on the 340.
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Bob Kidd

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Re: amp
« Reply #13 on: July 30, 2014, 06:45:50 PM »

This is true, but the op is looking for max headroom.  With the smaller amp clipping sooner, you're out of headroom.  You might as well just run all 4 off the 5050.  You'll have about the same watts/cab at clipping.  Another 5050 will provide a lot more headroom.

Going with the two 5050s.   ;D
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Bob Kidd

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Re: amp
« Reply #14 on: July 30, 2014, 06:55:04 PM »

Going with the two 5050s.   ;D. Thanks guys! Was going to stay with 340 but got 5050 for weekend on a favor. 2 725s over 3 728s per side ready to rock.
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Alex Rigodanzo

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Re: amp
« Reply #15 on: July 30, 2014, 07:50:06 PM »

The difference in "headroom" is less than 2dB.  He can tickle the clip lights on the 340.

2db per cabinet.  Times 4 cabs even with power compression you'd probably have 6db headroom.  I would rather not have to tickle the clip lights at all.  If you're tickling the clip lights and need to punch up a big solo, where's the headroom?

Bob, I'm glad you found another 5050.  You won't regret having extra nearly as much as you'd regret not having enough.
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David Morison

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Re: amp
« Reply #16 on: July 31, 2014, 08:12:06 AM »

2db per cabinet.  Times 4 cabs even with power compression you'd probably have 6db headroom. 

That's not how deciBels sum, here's one good reference. Basically, if in the scenario Tim outlined one amp clips ~2dB earlier than the other, it's only that 2dB off the max headroom.

HTH,
David.
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Alex Rigodanzo

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Re: amp
« Reply #17 on: July 31, 2014, 10:17:07 AM »

That's not how deciBels sum, here's one good reference. Basically, if in the scenario Tim outlined one amp clips ~2dB earlier than the other, it's only that 2dB off the max headroom.

HTH,
David.

I was referring to the difference from being limited by the pl, to what would be available with another 5050.

Just skimming that article you referenced, I already disagree.  He states +6db sounds twice as loud.  I've been a subscriber of Stereo Review/Sound & Vision since the 70's.  Every single article they've ever published on psychoacoustics says +10db is perceived as twice as loud by the majority of listeners.  There's more to "loudness" than simple db math.

I shouldn't have used the "per cab" statement, since we've already doubled the cabs by adding the second amp and we aren't doubling them again by going to the bigger amp.  I was thinking of one cab with 1000w doubling to 2000w is +3db (ignoring power compression).  But if you add a second cab with 1000w to it, it's +6db (ignoring power compression).
« Last Edit: July 31, 2014, 10:34:38 AM by Alex Rigodanzo »
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Tim McCulloch

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Re: amp
« Reply #18 on: July 31, 2014, 10:30:11 AM »

<face palm>
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Alex Rigodanzo

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Re: amp
« Reply #19 on: July 31, 2014, 10:37:19 AM »

<face palm>

Are you face palming my preference to rely on Stereo Review over some guy I've never heard of?  Sorry, but in my experience over the last 35 years, they are the most reliable source of unbiased audio information I've found.

Also, scroll up and you'll see I retracted the "per cab" statement as it doesn't apply to this situation.
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ProSoundWeb Community

Re: amp
« Reply #19 on: July 31, 2014, 10:37:19 AM »


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