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full Volume on power Amp?

#66
MVPBASS said:
So for me, running sound from stage while playing and singing, I can't go turn the poweramps up during the course of the night. I'd rather just push the master faders up. Nbd
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That's the idea in a nutshell. Once you learn each piece of equipment in the signal chain...mixer, processors, limiters, xovers, amps, etc....the power amps pretty much become the constant. Set it and forget it.

Riis
 
#68
Serious?
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Ya I wondered about that... would make me suspicious there was something wrong when a 1600 watt PA amp pops any breaker less than 20 amps. Got dusty heat sinks - skinny speaker wires? Or maybe you got hold of a skinny power cable - read the printed spec.s on the power cable, sometimes small gauge power cables will fool ya - they look full size because of the thick insulation but they aint.
 
#69
amos said:
When I dime the poweramp on my bridged QSC PLX1602 (1600 watt @ 4 ohm), I trip the breaker on anything less than 20 amps. So for the sake of keeping the power on during my set, I dial it back to 12 o'clock or so.
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...which is probably where it should be adjusted to start with but that, in and of itself, doesn't explain why you're popping breakers. JOOC and maybe having no bearing, what speaker enclosures are you running with 1600 watts bridged / attenuators dimed?

Edit: One more thing...the wheels are turnin': Is this a dedicated 20 amp breaker or may something else possibly be sharing the line? I've popped breakers in venues only to have some gal come out of the ladies' room saying "hey, the hand dryer isn't working!". You have thermal protection kicking in at the breaker and not the power amp itself so I'm curious.

Riis
 
#72
but y'all touched on it with the "breaker" reply.

I'll prolly start a new thread or just search more but I may use my preamp w/Crown Coredrive XLS1500 in a parade in May. We'll be using a gas generator to power the band. Any issue with consitent power to my/our rigs with a generator?

I think I recall a few posted issues with their Markbass amps shutting down when powered with generators? And I'd prefer to use either my LMII or F1 for this gig, just to lighten my load. If this is too OT, I'll do more searchin and new thread-it. Peace, ernie.

AND to stay OT, I been keeping my Crown amp @ 10:00-12:00 w/pre gain/volume knobs @ noon or little less, into a single UL-410, bridged @ 8 ohms. Expect about 1050 watts, works nice for my needs.
 
#73
Stupid question...

Preamplifier knob = ??

Power amp knob = gain??






bongomania said:
...With the caveat that only sending too much power into the speakers can blow them. ;)

Here's one way of looking at the preamp/power amp knob deal: The gain/volume on a preamp can be thought of as addition and subtraction. You add or subtract volume. The level knobs on a power amp, however, are like multiplication--it takes your preamp signal and multiplies it by the amount set by those power amp knobs.

Because of that, I tend to think of them like "coarse" and "fine" tuning controls, with the power amp being coarse and the preamp being fine.

Now, these are just convenient illustrations, they are not really a technically-accurate description. But it may help.
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#74
Thejamesjordan said:
I've heard varying opinions. Should I Dime out my power amp and control volume/ settings 100% through the pre?

Thanks,

Andy
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Worst way to do it, that maximizes the noise.

You start at the beginning of the signal chain and get as much gain as you can without clipping, then move to the next gain stage and do the same.

You want everything running as hot as possible early to minimize noise. Finally when you get to the power amp, set it so you can get as loud as you need to. Then you can control the volume at the preamp, or the power amp if its easier to get to.

Randy
 
#75
kawika5150 said:
Stupid question...

Preamplifier knob = ??

Power amp knob = gain??
Click to expand...

Not a stupid question!

Preamp knob(s): Gain - input trim, Master - volume

Power amp attenuators: output gain. Adjusts amp's output to respond smoothly & efficiently to the signal fed from the preamp's master. No two pairings interact in exactly the same fashion, that's why all parameters are adjustable.

Riis
 
#76
Or more technically:

The input level/volume/gain knob on a preamp usually controls an active gain circuit, a device that boosts your signal amplitude. More gain = more active boost.

The output level/volume/master knob on a preamp is usually a passive cut-only knob, like the volume knob on a passive bass. It just takes the preamp's full/maximum output and turns it down.

The gain/level/volume knobs on a power amp are harder to explain. Your signal from the preamp goes to an active buffer at the input of the power amp--this provides isolation and impedance correction to make a more ideal transfer of your signal into the rest of the power amp circuit. THEN the signal hits the gain knobs, which are usually passive volume knobs, cut-only. But then the signal goes on to a powerful gain stage that boosts your signal by a set amount. So the gain/level/volume knobs on a power amp are controlling how strong your signal is before it gets boosted by the gain stage.

In essence there is no difference in function between the output (master) knob on a preamp, and the gain/level knob on a power amp, except that they are separated by a buffer. This buffer can get clipped (distorted) by too high of an input signal, so really you can look at the main purpose of the master preamp output knob as something to turn down a bit if the power amp is getting clipped.

If you want maximum clean signal-to-noise, set the preamp output as strong as it can go without clipping the input buffer of the power amp--and then turn up the knobs on the power amp up/down for volume control. But as others have pointed out, the knobs of the preamp may be more convenient to reach than the ones on the power amp, and that's fine--in a club gig setting, signal-to-noise ratio is not an issue.

For maximum volume, set the preamp master as high as it can go without clipping the power amp input, then turn up the power amp as high as you can go without distorting the speakers.
 
#77
bongomania said:
Or more technically:

The input level/volume/gain knob on a preamp usually controls an active gain circuit, a device that boosts your signal amplitude. More gain = more active boost.

The output level/volume/master knob on a preamp is usually a passive cut-only knob, like the volume knob on a passive bass. It just takes the preamp's full/maximum output and turns it down.

The gain/level/volume knobs on a power amp are harder to explain. Your signal from the preamp goes to an active buffer at the input of the power amp--this provides isolation and impedance correction to make a more ideal transfer of your signal into the rest of the power amp circuit. THEN the signal hits the gain knobs, which are usually passive volume knobs, cut-only. But then the signal goes on to a powerful gain stage that boosts your signal by a set amount. So the gain/level/volume knobs on a power amp are controlling how strong your signal is before it gets boosted by the gain stage.

In essence there is no difference in function between the output (master) knob on a preamp, and the gain/level knob on a power amp, except that they are separated by a buffer. This buffer can get clipped (distorted) by too high of an input signal, so really you can look at the main purpose of the master preamp output knob as something to turn down a bit if the power amp is getting clipped.

If you want maximum clean signal-to-noise, set the preamp output as strong as it can go without clipping the input buffer of the power amp--and then turn up the knobs on the power amp up/down for volume control. But as others have pointed out, the knobs of the preamp may be more convenient to reach than the ones on the power amp, and that's fine--in a club gig setting, signal-to-noise ratio is not an issue.

For maximum volume, set the preamp master as high as it can go without clipping the power amp input, then turn up the power amp as high as you can go without distorting the speakers.
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How do you know if you're clipping the input buffer of the poweramp? By listening I presume?
 
#78
I must be the dumbest person in this forum, but I'm reading up on things and trying to learn this. I'm not savvy in this area like everyone else in here, so I undertand if some of you are irritated by my posts.:(

Currently, I have my master volume on my 4 PRO around 4 o'clock, and the Gain knob at approx. 9.5 o'clock. I do notice that the Gain gives me a "crunchier" and aggressive sound. Even at these settings, the peak light doesn't come on. Not even a blip. I'm just concerned on how much I can push the drivers from my GB NeoX 210T and 4x10 (4 ohm per cab).

I like the sound better using the EQ function on the front.

Don't mean to hijack the thread, but it has some connection with the OP on how far I can turn up these knobs without worry.

Ok, dumb question done.
 
#79
thudfromafar said:
How do you know if you're clipping the input buffer of the poweramp? By listening I presume?
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Yep, by ear. It's that nasty harsh solid-state buzz clipping sound. Now, of course there are some power amps that sound great when clipping--so the take-away point is not that clipping should be avoided like the plague, but that if the clipping sounds bad, there is something you can do about it. :)
 

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