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Double 10" Sealed Enclosure Advice please

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Peter Jan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 10:42am
An iPhone/iPad doesn't put out very high levels, so that's why you probbaly won't have distortion even with the levels on the amp turned up full.... well, given you turned the iPhone all the way up.
In general, you best have the source turned up as much as possible ( not to the point of distortion of course ), so you can set the levels on the amp as low as possible to give you the desired speaker level. Two reasons to do it like that : 1) have the best signal to noise ratio and 2) avoid ( to some extend ) nasty cracks/plops when accidental or on purpose unplugging or iPhone/other source plugged in, that has the volume wide open, when the amp is still on or already on.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 1:03pm
Originally posted by Jack1991 Jack1991 wrote:




I would like to know if its ok to have it up higher (even i no distortion) or if anyone has any tips for setting it correctly or any advice on it in general? πŸ™‚πŸ‘πŸΌ
Bear in mind, the labeling on that "gain" adjustment tells you which input signal voltage is needed to drive the amplifier to full power. Fully open, it is only 0,2V, suitable for battery powered consumer stuff like ipods etc.
"Normal" would probably be standard 0,775V consumer line level. The leftmost position with 6,5V would be appropriate e.g. when driving the amp with a PA processor such as behringer dcx2496. 

Remember to turn the amp input down if you change/plug any input connection while the unit is on. Better yet,turn it off. Otherwise you mught expect sudden loud noises while plugging Ouch
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 1:47pm
Thank you Peter Jan again for the answers! πŸ˜€πŸ‘πŸΌ


Also thanks bob4 too! Thats really helpful as i didnt understand the numbers on the gain knobs but that makes sense now. So i assume obviously the higher the gain the harder the amp is working which in turn reduces the battery quicker. Realistically though do you think it would be much difference in battery drain? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 2:23pm
The amp will only work as hard as you make it work. 

As Peter says the numbers refer to the voltage needed at the input, to get the output up to maximum power. It's more correct to refer to them as "sensitivity" rather than "gain".

The gain of the amp is a fixed quantity. Usually 26,30 or 32dB. Car amps rarely give this spec though.

What that pot does, is put a voltage divider between the input sockets and the actual power amp input. So when it's all the way clockwise, every bit of voltage you put into the input makes it to the power amp and you only need 0.2v RMS to get full output power. When it's all the way anticlockwise, it's bleeding off a lot of the voltage you put in, such that 6.5v RMS before the pot, becomes 0.2v RMS at the power amp input.

So you could have it set to 6.5v, but only be putting in say 3v of signal. You'd get just less than half power out of the amp. The pot itself, doesn't change the gain of the amp. It just changes the amount of input you need to get full power out. 

If you want to be able to measure the signal you're putting in or getting out, you can use a multimeter with a 20v AC range. If it's a cheap non-RMS type, use a 50Hz test tone as they're made to measure the mains power at that frequency.
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 2:53pm
Thanks studio45 thats a good analogy to explain it too and makes sense. The more i read it which is good. 

So theres no harm having it set too low. Just going too high could create distortion or clipping depending on input voltage. Correct?

And obviously the higher its set the harder the amp has to work. So a higher input could then have the gain set lower reducing how hard the amp has to work. Correct?


Edited by Jack1991 - 22 May 2020 at 2:54pm
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Peter Jan View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 2:58pm
Originally posted by Jack1991 Jack1991 wrote:

....So i assume obviously the higher the gain the harder the amp is working which in turn reduces the battery quicker. Realistically though do you think it would be much difference in battery drain? 

The battery drain will be proportional to the effective power put out by the amp, not the position of the gain/sensitivity/level pot. You can have the gain on the amp all the way down and have a source putting out say 5V or so, than the amp will drain the battery substantially, because it it close to maximum power.
With the gain on the amp all the way up, but a source barely touching 0,1V output, you’re not even at half power. It’s all relative πŸ˜‰.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 3:01pm
Originally posted by Jack1991 Jack1991 wrote:

So theres no harm having it set too low. Just going too high could create distortion or clipping depending on input voltage. Correct?
Correct
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 3:03pm
Oh right i see, i thought the gain would effect the power drain.

Right im starting to get it now then. Thanks again!

So for the battery to last longer then, i would be best off using a low voltage input like a phone. Instead of say decks or something more powerful.


Edited by Jack1991 - 22 May 2020 at 3:04pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 3:08pm
Originally posted by Jack1991 Jack1991 wrote:

And obviously the higher its set the harder the amp has to work. So a higher input could then have the gain set lower reducing how hard the amp has to work. Correct?
No not exactly... as he said it’s just a (passive) voltage divider, not a real gain and even if it was, at that point were talking low voltages with relative high impedances or a very low power difference in whatever the position of the β€œGain” would be. Even if it was a true gain (which it is not), it would still be very, very, very marginal in terms of power consumption or battery drain.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 22 May 2020 at 3:17pm
Cool okay thanks very much again for all your help!

I will be getting it all out soon for a first test in the garden. Its only been tested in my garage so far but it really exceeded my expectations indoors. The true test is outdoors i think though. Thought id best wait for a friday to test it in the garden as neighbours probably wouldnt be too pleased midweek haha πŸ˜‚

Also last question, i have a 'Equaliser FX Pro' app on my phone which i have to use when i plug my phone in via aux as for some reason the volume goes really low when on aux. Anyway, it has a volume booster which i turn on and then also i adjust all the EQ through there, which seems to work really well. I assume this also wont have any significant effect on the power draw as now it seems like its also kind of similar to the amps gain knob. Or am i very wrong?


Edited by Jack1991 - 22 May 2020 at 3:26pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 23 May 2020 at 1:30pm
The only thing that really affects battery life is how loud you have it playing.

All of the other adjustments you are talking about are just ways of getting to that final output.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 23 May 2020 at 1:38pm
Perfect thanks mate! πŸ˜€πŸ‘πŸΌ
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