Amplifier input attenuators (or volume controls)

Рет қаралды 8,022

4 жыл бұрын

A look at the "volume controls" (input attenuators) that are found on many amplifiers. This is a brief overview of what they actually do and how they are sometimes misused.
Whether they are called "volume controls" or "gain controls", or etc... it's important to know what they do and how integral their use is with your sound system.
It's been awhile since we posted a non-event video. We hope to have more videos soon covering equipment and how that equipment is used.

Пікірлер: 44

@isettech Жыл бұрын

Proper use of the amplifier attenuators is as follows. 1 Set up your console for nominal levels all the way through. This is proper gain structure and is used in both a small club and in a large amphitheater. This provides some protection for the amplifier and speakers. With proper console setup, the maximum headroom is about 12 db. Most consoles provide a nominal output of +4 DBU. Most consoles clip at about +18 DBU, so there is no more after that. Now set the amplifier attenuators for the maximum loud sound for the event. This can match the speaker rating, Venue DB limits, or safe hearing level for the event. This allows the console to operate with the proper headroom, high signal level of +4 DBU to provide the maximum recommended signal for the noise level of the system. Yes this operates at the best S/N ratio for the cleanest sound with little chance of running out of headroom. How not to operate the attenuators. 1 Turn them all the way up. This amplifies the noise floor. The console operates with the output very low to manage output levels. This provides poor S/N ratio, and allows the amplifier to be driven to clipping at maximum power, which may be more than 30 DB of headroom, resulting in blown speakers in a runaway feedback conditioin when a guitar is set on a monitor, or a mic is dropped, etc. Most consoles are able to output between + and - 12 to 15 volt peaks before clipping. Your amp attenuation should never be turned up for sensitivity for a 1.2 volt signal. The console can provide up to 30 volts peak to peak. Check the specifications for your console. Industry standard is +4 DBU balanced signal. The extra gain is for when you use a home receiver, VCR, cassette deck, etc which operates on lower voltage and outputs -16 DBU as the nominal output. This includes consumer grade tablets, MP3 players, some DJ USB powered mixers, etc.The DJ's with RCA connections can use the extra gain. A pro board with the nominal +4DBU does not need the attenuator turned to the max ever.

@stageleftaudio Жыл бұрын

Great info.

@jasonhpratt 3 ай бұрын

That helped a lot !thank you so much 🙏

@stageleftaudio 3 ай бұрын

Glad it helped!

@makstaz79 3 жыл бұрын

Thanks for this information I found it very helpful, keep up the good work .

@stageleftaudio 3 жыл бұрын

Thank you for your comment.

@3dprint-tech787 4 жыл бұрын

Very usefull, thanks for sharing!

@themilkywaygalaxychannel684 4 жыл бұрын

Awesome

@LucasWasson 4 жыл бұрын

Great video I would love more info on powered speakers. Should I be treating them the same and be running them wide open as you called it? Or just turn them up to what's loud enough?

@stageleftaudio 4 жыл бұрын

Good question. The attenuators on powered speakers should be kept where the manufacture indicates -0- db is. This is usually identified by a detent location, or a marking (similar to the DSR speaker in the video). Many times, the position is at "12 o'clock".

@LucasWasson 4 жыл бұрын

@@stageleftaudio great to know thank you!

@DhanjitMr 4 жыл бұрын

Sir Show some demos. Thanks for the knowledge..

@jessecoonen7881 4 жыл бұрын

I have EV ETX boxes that are self powered. They have an input gain or attenuator and a master volume knob. I’ve been running the master wide open and keeping the input at unity. They’re 2000 watts peak power but still don’t seem very loud when they start to limit. Any thoughts?

@stageleftaudio 4 жыл бұрын

If the speaker power rating is what you indicated (2000 watts peak), the speaker is actually a 1000 watt RMS (or 500 watt continuous) powered speaker. If the "limit" you are seeing is on the input stage, this usually indicates the source signal (feeding the input of the speaker) may be too hot; the source level should be turned down. If the limit is seen on the amplifier, this means the limits of the speaker is being reached; there's not much you can do about this type of situation. However, it's possible the input attenuator may need to be increased (assuming you are getting NO limit warnings on the input stage). But, care should be taken to not increase the input attenuator too much. Depending on where you are standing for your reference to how loud the speaker is, the 90-degree by 60-degree horns are great for near and mid-field applications. Unfortunately, those horns do not do well for far-field events.

@travisgulley2652 2 жыл бұрын

If the clip led on a power amplifier comes on when the volume on the mixing console is cranked up halfway will the speakers be just fine and not blow

@stageleftaudio 2 жыл бұрын

If the speaker's power is not rated to match the amplifier power, the speaker will become damaged. The clip lights on the amplifier is what you should pay attention to... not so much the position of the fader on the console.

@travisgulley2652 2 жыл бұрын

Do the low frequencies on the equalizer need to be turned up if you are using a power amplifier to power subwoofers

@stageleftaudio 2 жыл бұрын

Low frequencies on an EQ should never be turned up unless it is to support a special effect. EQ should be used as a subtractive EQ first... before being used as an additive EQ. If one low frequency needs to be turned up, this is usually ok. However, If many of the low frequencies have to be turned up, that is usually an indication of improper mixing, incorrect gain structure, somethings wrong with the speakers, or using the wrong speakers for an event.

@travisgulley2652 2 жыл бұрын

Will the clip indicator leds on a power amplifier still be able to come on if a compressor is hooked up to a power amplifier

@stageleftaudio 2 жыл бұрын

Yes.

@valentingheorghe1693 Жыл бұрын

Know the nominal level and the maximum output level of the mixer, which may be +18 dBU, +20 dBU or +24 dBU. The clip level of the mixing console is, usually, marked at 6 dB over the last yellow/amber leds on the level meters. If the mixer has a nominal level of +4 dBU (0 dB mark on the level meters) and a maximum output level of +20 dBU (+16 dB red led on the level meters), I have 16 dB of additional dynamic range above the nominal level. I intend to use the maximum dynamic range of the mixer and to ensure the best signal to noise ratio in the system, before the signal is sent to the amplifier. Therefore, I set the channel input gain to hit the 0 dB mark on the meters, then I raise the channel fader or the master output fader fully up (+10 dB), to hit the last yellow/amber leds on the meters (+10 dB), just below the clip LEDs. This offers me 6 dB of headroom before clipping the mixer output. On the amplifier side, set the input sensitivity switch to 1.4 V RMS to match the mixer's nominal level and adjust the sensitivity controls to -10 dB attenuation for rated continous power output. At this point, the continous power output of the amplifier is about 1 dB below its maximum power output. The above procedure it is based on the assumption that the loudspeakers continous power rating are matched with the amplifier continous power rating. If a compressor/limiter is used between the mixer and the amplifier, the mixer output level can be increased to its maximum level (+20 dBU) and the limiter threshold should be set at the point where it begins to catch the signal peaks, with an additional 3 dB of attenuation, for safety. If the speakers continous power rating is lower than the amplifier continous power rating, lower the amplifier input sensitivity controls or the mixer master output level according to the power you need for the loudspeakers and allow for about 1 dB of headroom also for the speakers.

@travisgulley2652 2 жыл бұрын

Does the amperage of the fuse on the power amplifier determine how much rms power the power amplifier puts out.

@stageleftaudio 2 жыл бұрын

Any fuse or circuit breaker in an amp limits the amount of power allowed into the amp; this can sometimes coralate to the amount of power ouput (but would probably be a continuous output, but not RMS).

@travisgulley2652 2 жыл бұрын

Does turning up the volume on the mixing console cause the power amplifier to draw more current.

@stageleftaudio 2 жыл бұрын

Most of the time, yes.

@travisgulley2652 2 жыл бұрын

Do some pro audio power amplifiers have a bass boost and or a loudness feature that you can turn on or off.

@stageleftaudio 2 жыл бұрын

I'm not aware of any pro audio gear that offers that.

@Dabbyreverb Жыл бұрын

So i have issues with the whole sensitivity stuff, after setting up and having my gain structure in place from the mixer board, turning up my amps to the highest causes lots of feedback issues. Although i use a speaker management at 0db. What could be the solution. Thanks

@stageleftaudio Жыл бұрын

Feedback issues are mostly caused by improper gain staging on a microphone (at the console). The amplifiers have nothing to do with feedback, other than amplifying a feedback-issue. The speaker management system has nothing to do with feedback other than ensuring input signals are "gained" correctly for output to amplifiers (or powered speakers). 1. Make sure the input gain on the console is set for the microphone and for the instrument (or vocal) that it is being used for. 2. Make sure the mic is not facing any loud speakers. 3. You may need to apply some EQ cuts for the channel the mic is connected to, depending on what the audio frequency of the feedback. Setting gain is very dynamic and changes between different mics, different setups, different consoles... so, a solution to feedback may take a little work for your setup compared to someone else's setup. Make sure there's not too much gain being used on any of the microphones.

@Dabbyreverb Жыл бұрын

@@stageleftaudio so gaining a mic must not necessarily be at 0db on the meter for analogue mixers ?

@stageleftaudio Жыл бұрын

If you are talking about a -0- db marking on gain knob, you are correct. If you are talking about -0- db on a meter, it's a little different. Vocals should be around -0- db (maybe -3db) on a meter. Drums / percussion instruments can be around +9db. To get that point, it may require a gain knob to be adjusted more/less of what the console is showing as unity (the unity marking on the input channe). Gain and meters are not static measures... if they were, their settings would either be on or off. Gain settings are very dynamic and will require their own setting.

@travisgulley2652 2 жыл бұрын

Does hooking up a graphic equalizer to a power amplifier effect how loud the speakers get.

@stageleftaudio 2 жыл бұрын

Yes, but the "loudness" will depend on which EQ band is boosted (or cut). Also, EQs are not actually connected to an amplifier. They are sometimes placed in between the console and the amplifier. An EQ is actually considered to be "inline" with the signal path if it is placed between the console and amplifier.

@travisgulley2652 2 жыл бұрын

If a power amplifier has a 15 amp fuse on the back of the power amplifier and outputs way more than a 1000 watts rms does it have to be plugged directly into the wall outlet and not a power strip

@stageleftaudio 2 жыл бұрын

All amplifiers (especially in production work) should be plugged into receptacles, not power-strips, unless the total anticipated power from the amplifiers that are plugged into a power strip, is less than what the power-strip is rated for.

@Extremeadventuresandevents 4 жыл бұрын

hi, bob. can you please recommend for me entry level industry standards wireless microphones that are tech rider friendly. thanks

@stageleftaudio 4 жыл бұрын

Actually, "entry level" and "tech rider friendly" don't usually belong in the same sentence. Also, the term "rider friendly" is very subjective and is open to artist/provider interpretation. With that said, you may want to look at Sennheiser, MiPro, and Shure. Decent entry level mics can still be expensive. I can't make any recommendations on model numbers... there's too many! Look for units with 30mW transmitters. These usually have very good range. Be careful if you find something used. In the USA, certain radio frequencies are now outlawed (due to the FCC taking over the frequency ranges); many people are now selling their older (outlawed) wireless mics at very cheap prices.

@Extremeadventuresandevents 4 жыл бұрын

Hi, i really value your opinion and advice. thank you

@travisgulley2652 2 жыл бұрын

Why do some power amplifiers say caution high voltage on the speaker terminals on the back of a power amplifier.

@stageleftaudio 2 жыл бұрын

All amplifiers put out voltage... not actually watts. If you are not carefull at the speaker terminals of an amplifier, you will get shocked by the terminals. The more power an amp puts out, the stronger the shock.

@darrenchase886 5 ай бұрын

I have the levels maxed out i have it connected to my avr pre outs

@stageleftaudio 5 ай бұрын

For which "power"? I'm not sure what your question is. There's an emoji in the middle of your question.

@travisgulley2652 2 жыл бұрын

Is it safe to plug pro audio power amplifiers into a power strip or is it a fire hazard.

@stageleftaudio 2 жыл бұрын

It depends on much power the amplifiers are anticipated to draw. Normally, amps are not plugged into power-strips... not because of potential fire, but due to the circuit breakers (found in most power strips) that usually trip below their rated load. Power strips can be used, but the total potential load plugged into a power strip needs to be less than what the power strip is designed to handle.