Increasing amplifier output

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tom_tom_go
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Increasing amplifier output

Post by tom_tom_go » Fri May 31, 2019 6:54 pm

Hi,

Is there a way to make an existing amplifier more powerful?

Reason I ask is my acoustic smoker I am working on works better when the louder horn noise from the amplifier is played. The engine running noise is not as loud as the horn so the smoke output is not as good.

This is the amp I am using:

https://www.mtroniks.net/prod/Sound-Sys ... d5mSDT.htm

Bit clueless when it comes to amps so appreciate advice.

Cheers!

Tom

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Re: Increasing amplifier output

Post by ge_rik » Sat Jun 01, 2019 7:49 am

The simplest approach is probably something like this, Tom

https://www.ebay.co.uk/itm/123677432391

Rik
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Re: Increasing amplifier output

Post by tom_tom_go » Sat Jun 01, 2019 8:46 am

Thanks Rik, I am limited by voltage though as I am running a small battery. I only need to go to about 10 watts.

I found various preamplifiers that are small and only require a low voltage. I can't seem to find a clear explanation as to whether a preamplifier boosts overall volume or just improves sound quality? The speaker I am using was not cheap so happy with the clarity of the sound.

You can see in this video how the smoke output is better with the louder start up and horn sounds compared to the running noise:


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Re: Increasing amplifier output

Post by philipy » Sat Jun 01, 2019 10:06 am

Tom, I don't know if this article will help or add further confusion?
https://musicaroo.com/preamplifier-vs-amplifier/

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Re: Increasing amplifier output

Post by Busted Bricks » Sat Jun 01, 2019 11:18 am

As I understand it the device you are using has a built in amplifier but it is not powerful enough? You can't just add another amp to the output. However if the is a line out (pre-amp signal) then you can hook it up to a more powerful amp. If you are limited on voltage then there are DC/DC boosters available. However you need to be sure the power source can keep up with the added current draw.

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Re: Increasing amplifier output

Post by gregh » Mon Jun 03, 2019 6:02 am

can you just clarify for me, what you are trying to do, so that maybe I can help.

You have a smoke producing thinggie and you are powering it from the mtroniks amplifer ? (how does it fit in a loco? looks like a big thing)
Don't these smoke things work off DC?
Are you also powering a speaker from the amp as well as the smoker? in parallel?
You are wanting a higher voltage supplied to the smoker when the sound is loudest?

If the answer to all the above is yes, then I'd be asking, why don't you use dc to power the smoker? You don't need 'hi fidelity' to run it.
As a first guess, I'd say a diode, resistor, capacitor and transistor is all you'd need.
Do you have any idea what current the smoke unit takes and what voltage?

But once you explain a bit more (and I manage to understand) maybe I can offer a circuit idea.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Increasing amplifier output

Post by tom_tom_go » Mon Jun 03, 2019 9:07 am

Hi Greg,

It all started here:

viewtopic.php?f=24&t=12275&p=144866&hil ... ic#p144866

The 'smoker' is my attempt at an accoustic smoke generator. The idea is the louder the sound the more air is forced into the smoke chamber and therefore more smoke is produced (it also is in sync with the sound because of this).

The heating element inside the smoke chamber runs directly off the battery at a constant voltage. I have yet to post my recent work, however, our Rik and Andy @ Mircon R/C (www.micronradiocontrol.co.uk) have been very helpful in getting me set up with a working Deltang Prog4 so I was able to reprogram the Rx65b to turn the heating element on/off using the Tx (this also required using a latching flip-flop IC).

The speaker is connected to the sound card speaker outputs. The soundcard is powered from the battery.

All I require (if possible) is to make the sound from the amp louder. The speaker can handle a higher wattage so this isn't an issue.

The entire loco is powered from a 7.2v battery and all the workings including the battery fit inside the loco (just).

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Re: Increasing amplifier output

Post by gregh » Mon Jun 03, 2019 10:02 am

tom_tom_go wrote:
Mon Jun 03, 2019 9:07 am
Hi Greg,
It all started here:
viewtopic.php?f=24&t=12275&p=144866&hil ... ic#p144866
The 'smoker' is my attempt at an accoustic smoke generator. The idea is the louder the sound the more air is forced into the smoke chamber and therefore more smoke is produced (it also is in sync with the sound because of this).
The heating element inside the smoke chamber runs directly off the battery at a constant voltage. I have yet to post my recent work, however, our Rik and Andy @ Mircon R/C (www.micronradiocontrol.co.uk) have been very helpful in getting me set up with a working Deltang Prog4 so I was able to reprogram the Rx65b to turn the heating element on/off using the Tx (this also required using a latching flip-flop IC).
The speaker is connected to the sound card speaker outputs. The soundcard is powered from the battery.
All I require (if possible) is to make the sound from the amp louder. The speaker can handle a higher wattage so this isn't an issue.
The entire loco is powered from a 7.2v battery and all the workings including the battery fit inside the loco (just).
I really had the wrong end of the stick - assuming you wanted to increase the smoke output. Sorry.
BUt here's some info about how much power you can get out of an amplifier - may not help you, but you can see the relationship that shows the max you can get with your battery and speaker.

for a simple amplifier - you can tell this type - they have a large capacitor ( hundreds or thousands of uF) in series with the amp output to the speaker, and the other side of the speaker connects to 0V:
Max possible power that the speaker can produce, in watts is ... square the battery voltage and divide it by 8. Then divide the result by the speaker impedance.
For the Mtronics amp you use, the specs state: max 12V battery and min impedance speaker of 4 ohms and a max power output of 4W. So the calc above gives max power = 12*12/8/4 = 4.5 watts - close enough to specs.
But if you only have a 7V battery and use an 8 ohm speaker, you can only get 7*7/8/8= 0.75watts, or 1.5W with 4 ohm speaker.
If your battery volts and speaker are fixed, you can't get any more power into the speaker with the amp you have. Different speaker configurations may make a difference to the volume you hear.

A solution is to use a bridge amplifier. on the output of your mtronics one.
A bridge amplifier - it's hard to determine from specs whether an amp is a bridge type but it is called a 'class D' - it has no capacitor in series with the output to the speaker and the speaker is NOT connected to the 0V, but to two separate outputs. It is essentially two amplifiers. It can put out 4 times the power of the simple amp. And that's the max you can ever get with your battery volts.
The amp referred to by Rik 'seems' to be a class D so could give you 4 times the power. https://www.ebay.co.uk/itm/123677432391
I can't find data on what it's gain is. You would have to put a voltage divider between the output of the mtronics amp and the input to the one above.

Or as Busted Bricks says, use a dc/dc step up converter to give more volts. Or more battery!

Anyhow, you're doing Brilliant work. I love the effect.
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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Re: Increasing amplifier output

Post by tom_tom_go » Tue Jun 04, 2019 8:27 pm

Thank you for your detailed answer Greg.

I tried running the sound card before off it's maxed allowed voltage of 12v and the loudness is no different to when running off my current battery of 7.2v - why is that?

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Re: Increasing amplifier output

Post by gregh » Wed Jun 05, 2019 8:17 am

tom_tom_go wrote:
Tue Jun 04, 2019 8:27 pm
Thank you for your detailed answer Greg.
I tried running the sound card before off it's maxed allowed voltage of 12v and the loudness is no different to when running off my current battery of 7.2v - why is that?
Interesting question. I must admit that there are a couple of unstated assumptions in all my calcs
1) is that the input voltage is enough to cause the output to get to the max voltage out.
2) there's no distortion caused by trying to 'drive' the output to voltages higher than the battery ie no clipping.

But the basis of the answer is that all my discussions above refer to the MAXIMUM power you can get from a given battery supply and speaker resistance. You can always get less power if you have a lower 'input' voltage.

If you have the volume at a set level with a 7V supply, the output to speaker doesn't change when you up the battery voltage.
But maybe you could have turned the volume up with the higher voltage battery?
Greg from downunder.
The Sandstone & Termite's website: http://www.members.optusnet.com.au/satr/satr.htm

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