Karaoke Forums

Scenario's one and two ultimately end up being the same thing. Remember, the knobs on your amplifier are input sensitivity, not volume controls. In other words, they adjust the level of the incoming signal, not the amount of amplification that will be applied to it. So if you cut that incoming signal by half at the amplifier but make up for it by increasing the signal coming into the amp by double, you'll ultimately get the same output from the amplifier. Now there are implications as far as noise floor but that's a completely different conversation.

As far as #3, I agree, I don't know why you would use this in your setup. Given the good match between amp and speakers you'd be better off sending 2-channel mono out of your console to the amp and leave it in normal stereo mode (unless it has a dual mono setting which some amps do). If you do run in bridge mono, you have a couple concerns to deal with. First, if you're connecting both speakers (which I assume you would because of power handling concerns) you've now reduced the load that the amplifier sees. Wiring two 8 ohm speakers in parallel will result in a 4ohm load at the amp. So now you have to check to see if your amplifier will tolerate a 4ohm bridged mono load (the equivalent of 2ohm stereo). Then you have to look at the power output of the amp at 4ohm bridged mono and make sure that it doesn't exceed the power handling of the speakers (in this case 2x500, or 1000 watts). Obviously it will because at 8ohm bridged mono it's already up to 1500W. In the case of your P5000s, it will run 4ohm bridge mono but it produces 2600W peak in that configuration. So the overall answer is if you bridge your amp, whether it's into a single 8ohm speaker load or a dual speaker config at 4ohms, you'd have to be extremely careful because you now have far more amplifier than your speakers can handle.

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DJ Tony
Let It Rip Karaoke

parallel is parallel, mono or stereo. It means one speak to each side of amp.

Establish mono at board input using two into one trs jack.

No need to bridge amp

Not quite sure what that statement is in response to so I'm having trouble making sense of what you're trying to say.

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DJ Tony
Let It Rip Karaoke

What about during oscillation? Watts to speaker can double, causing watts to exceed speaker peak handling power. Please explaln this scenario....thank you in advance.......

Sorry Johnny I don't understand.
If the amp is matched to the speaker...
A 500W amp is incapable of putting out 600W.
What will go to the speaker will be like a square wave.
That is described at the top of this page.

He had stated that he now understood parallel in mono.

I just wanted to make sure he understood it was the same in mono andboth stereo....It sounded like he wanted to bridge amp to obtain mono, so I threw that in and told him to get mono at board input and leave amp in parallel. That way he could run wide open and have mono unbridged.

Never heard the phrase or condition you described....Try to explain please

No, but you are setting yourself up to put full amp power to speaks if amp input from mixer reaches max knob setting. That's fine with matched speaks, leave the door open wide.

Keith. Stop it.
These guys want easy to understand.
You know how it works.
Do simple. Please.

Ok, OK!

Simple version:

Step 1. Place "on" / "off" switch in "on" position

When everyone gets that done, then we go to step 2.



Oh, I forgot you wanted me to explain 'how it works". Simple, it's MAGIC, yep pure magic. You see, each component contains magic smoke. If you let the magic smoke out, it no longer works and you can't capture the smoke and put it back it in...I've tried.... You gotta buy a new one that has the magic smoke from the factory... So don't fry it, or the smoke will get out.



Sorry, just kiddin....I got too much time on my hands, huh?

Hey, keep going. I understood it so far.......

Eeek. I got lost on the magic smoke.

deleted post

Willie Nelson wasn't over visiting last night when all this occurred was he?

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DJ Tony
Let It Rip Karaoke

MEDIC

We have a Yamaha P5000S amp and 2 C115V speakers. I really have no clue what you mean by noting the sensitivity ratings and then adjusting accordingly. The sensitivity rating for the speakers are 99dB SPL (1W, 1m) <----no clue what that means either.

"The decibel has no actual numerical value, but is used only to express a ratio between two voltages, currents, powers, or impedances. The decibel uses logarithms to the base 10 called LOG. This should not be confused with the natural logarithm to the base "e" called LN used in many electronic formulas. Examples of decibel calculation: To calculate for voltage, current, SPL, distance: 20 Log X1/X2. To calculate for power = 10 Log P1/P2. "

kinda like the way they rate earthquakes

MEDIC

Exactly, which is why I'm trying to simplify this for everyone. Speaker sensitivity really doesn't affect gain structure. Speaker sensitivity in simple terms just measures how efficiently your speakers will use the power from the amplifier. If you have two speakers, one rated at 104dB another at 95dB being provided the same power (for rating purposes they usually use 1W at 8ohms and measure the SPL at 1 meter) the speaker with the rating of 104 will produce a louder result than the one rated at 95.

As far as gain structure (in this conversation the discussion of matching your amplifier's input sensitivity to the signal received) here's a simple explanation of what Keith was after. In the ideal world, the situation you want is when the output meters on your console show a level of 0db that the input sensitivity on your amplifier would be set such that the level seen at the amplifier is also 0db. The reality is that this is only a theoretical description and in reality you wouldn't want this to be the case unless your console and amplifier had the same headroom. So instead the goal becomes well let's make sure that the console and the amplifier would hit clip at the same level, this way you know that as long as your meters don't show clip (again I'm over-simplifying here) the amp won't clip either. In reality this isn't even totally true, but to keep it simple that's the effective goal.

The problem is that in order to actually setup your amplifiers this way requires a lot of time and some analysis tools that most of us don't own. Even if you have the time and tools, there's the question of is it worth it? To me, know. It's much easier to run the input sensitivity on your amplifiers wide open and use your meters, indicator lights and ears (as well as common sense) to ensure you're not running things into clip. Keep your levels sensible and you'll be fine. Indeed you'll find that many (if not most or all) touring production companies do the same. Make sure your amps are well match to your cabinents and then keep your levels in the realms of the sane (which means avoid letting the output get near 0db). This is the approach I recommend, especially for a novice.

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DJ Tony
Let It Rip Karaoke

Last night I tried wide open with the amp. It just didn't sound as clear. Then I backed it off to 6db (on the knobs on the amp) and it still didn't sound as clear as before. I finally put everything back to the way I had been doing it and the sound cleared up.

I don't know if I am picking up noise when I turn it up so it doesn't sound as good or what.

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Kevin

In general, you'll get a better noise floor running the amps full and the console lower, especially with the level of equipment we're all using. However this is not a hard and fast rule and certainly depends on the mixer and amps you're using.

I'm surprised to hear of your experience, but anything is possible. Certainly you may have been picking up noise in the signal lines between the mixer and the amp if you're not using balanced connections. Also if there's any ground loop hum in your system going this route (maxing the amp input) will make it much louder.

If the problem is audio clarity and not a noise issue, my guess is that some quick work on the EQ would probably straighten it out. Frequency response across the spectrum can change significantly based on signal level, so it is conceivable that the way you're EQ'ed for your current gain structure isn't translating well under the revised gain structure.

Now I say all this with the assumption that since you cranked up the input sensitivity on the amp that you ran your console at reduced levels from what you would normally run. If not, then we're comparing apples and oranges and this whole thing is moot.

In the end, if what you've been doing is working for you, then there's no pressing reason to change your approach. You know, if it ain't broke don't fix it. You're not going to damage anything or run into any critical issues they way you've been doing it, so I don't see any reason you should change now (unless you are having a problem, then let us know what that is.)

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DJ Tony
Let It Rip Karaoke