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Asking about mixer

Started by trialabc, January 11, 2011, 10:26:36 PM

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trialabc

I wanna make a mixer, but not sure how....
What I want is just to combine all inputs (likely to be 4 inputs) and output to two speakers.

Should I consider it as a power amplifier?
Or is it too difficult to a beginner like me?

Thanks in advance!

bry melvin

well a mixer Looks more complicated than it is...because it has sections that are repetitive for each channel.

It would be simpler to build it as a mixer PREAMP only than just use a power amp.  Here's an example schematic of a mixer amp I've been using for about 15 or 20 years...to see what you would be getting into

trialabc

Thanks for the schematic first.

I see there is a effect out and effect return. In case I don't need any effect, I can just connect the two?

phatt

It will depend what you want to amplifiy and do you mean two speaker as in stereo?
Do you want guitar inputs or balanced mic inputs?

You do need to be a little more specific. 8|

Meantime heres a fairly simple circuit,, I own this Amp and I use it for keyboards and guitar.
Obviously simple to add more channels.
Phil.

trialabc

At this point, I think it will be required to support 2 mic, and 2 guitar inputs.

Well, if I can have the equalizer like the first schematic you posted would be good, but that's less important.

What I am concern about is the power and possibility of achieving it. I am concerning about the power because it would be powered by 12V battery.

Maybe I should try using a summing up circuit for it?


trialabc

For the outputs : at least 2 speakers like in stereo or maybe 4 speakers.

2 speakers for stage (so that we can listen what we are playing) and 2 speakers for audience

phatt

Yes and I want a 1,000 Watt Amp that runs on a 9Volt battery. :)

Hi trialabc,

Arrh mate I think you need to do a reality check. ;)

I guess if you don't have much experience with gear then it's understandable that you might think these things are simple to achieve.
I think if it was that simple then it would have been done long ago.
Sorry chum, What you are asking is possible but not practical. :loco
Big power Amps suck up a lot of power and you would go broke buying the truck batteries needed to run it all.

For that system to work you need to look at portable power generators that output mains power then you can use normal mains powered equipment.
That would be the only sane way to approach that situation.
Cheers Phil.

trialabc

Thanks for your reply first.

But first, perhaps we can forget about the battery problem first.
Previously I successfully use an inverter to power a line 6 spider III amp (max 75W ) using a battery(12V 17Ah). But due to this kind of configuration, I think there is about 50% power loss due to 2 transformers. Well, at least I can play for 3 hours loudly. It has already achieved what I wanted to do.

As a result, this time I try to power a mixer. However, if I use the same configuration like above, I will still have 50% power loss.
Therefore, I want to make my own mixer for that. As a result, I only required for one transformer, say 30% power loss. Perhaps we can reduce to 2 speakers? Does this sound possible?




joecool85

I don't think you're losing anywhere near 50% of your power by using an inverter on an AC powered amp.  As far as power at the speaker, you will get 100% what you would get while plugged into the wall (assuming you inverter can keep up).  Efficiency wise, you will lose some by using the inverter, I'd imagine on the order of maybe 10% or less.  You can't really count any efficiency lost in the power transformer inside the amp because you would have lost that while plugged into a wall outlet anyway.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

trialabc

So when it is marked as max 75W, it already counts the lost of transformer?

joecool85

Quote from: trialabc on January 14, 2011, 10:34:42 AM
So when it is marked as max 75W, it already counts the lost of transformer?

If it says 75w on the back near the power chord, that is the maximum the amp will draw.  It probably puts 60w or so to the speaker max.
Life is what you make it.
Still rockin' the Dean Markley K-20X
thatraymond.com

trialabc

Quote from: trialabc on January 14, 2011, 12:18:36 AM
For the outputs : at least 2 speakers like in stereo or maybe 4 speakers.

2 speakers for stage (so that we can listen what we are playing) and 2 speakers for audience

Sorry Phatt, I think the word "stage" may confuse you a little bit. I don't need very large power for the speakers in fact. I think two 100W speakers will do. Hopefully this way sounds more practical.

phatt

Hi trialabc,
             Scratching my head.
Your comment of 12V 17Ah lead acid battery (which i assume, is about the size of a motorbike battery) would NOT have the stamina to run a 70 Watt Amplifier for 3 hours. (hey I could be wrong) but if it was a small 10 to 20 Watt SS amplifier then yes 4 hours is feasable.

I helped setup a small rig like this for a chap who plays at a market and he used a DC converter into a small little amp.

Joe Cool has probably nailed your confusion of Wattage Power.
Your 75 watts is likely what the Amplifier Draws from the mains.

Actual Amplifier Wattage is going to be far less than that.
I checked the make and model and unless I've got the wrong model your amp is 15 Watts. so yes 3 to 4 hours is what you would get.

BTW, A preamp mixer circuit draws little current and could be run on it's own seperate dry cell batteries. probably get 20 hours easy.

It's the powerAmps that chew up the current demands.
Phil.

J M Fahey

Short solution: buy a 12V powered car audio amp (it already has its own internal inverter), and make a simple 12V powered mixer.
Read carefully the small print in its user manual; "1200 Car Watts" usually mean 2x45W RMS
Remember that a 12V 17AH can provide 100W continuous (meaning 60W RMS audio) for 2 hours.
That means a 3 hour show if you don't play *continuously* ,  if you stop between songs to talk a little, say a couple jokes, tune your guitar, etc. , which you should do anyway to avoid boring the audience.
Based on this, calculate your needs.

trialabc

Thanks a lot guys! Anyway, I think I will give it a try to see what I can do. In case the 12V 17Ah is not ok, I will buy a bigger one :p :duh

The reason that I don't wanna use portable power generator is because it is smelly and noisy. Moreover, I have to buy fuel for it. It's kind of troublesome.

First, let me find some time to make the mixer. Probably need to wait till Chinese Lunar New Year.