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darren adcock

Sep 26, 2016
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Hi again.

I'm looking for some pointers please.

I'm making mini synths off of mfos. I am wanting to have them all to be portable and have an amp and speaker in them. However I know very little about amps and speakers. What kind of thing am I looking for in amp circuits? How do i know how good the sound will be in terms of not distorting? Also I will need a circuit that doesn't draw too much current. In terms of speaker i need to reach a balance between size and frequency response, when i'm looking at speakers which parts of the data do i need to pay best attention to?

I wish to keep the circuit analogue

Obviously if there's just a book i should read I shall do that.

Best and thanks

Darren
 

Audioguru

Sep 24, 2016
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Loudness is produced by how many Watts an amplifier can produce into a speaker that is near you. If the speaker is far from you then it will not be loud unless the Watts is increased. The number of output Watts must be with a rated percentage of distortion number. 0.1% distortion or less cannot be heard.The cheap Chinese amplifier does not mention distortion so its 3 Watts output is probably with extremely high distortion and might be only 1 Watt at a reasonably low distortion. Battery size also determines the loudness of an amplifier. A little 9V battery can feed a 1/2 Watt amplifier. Six AA alkaline cells can feed a 6 Watt amplifier.

How loud and how close to you do you want? A cheap clock radio produces about 1 Watt but with lots of distortion. A home hifi produces 100 watts or more at very low distortion.

A woofer is a low frequency speaker. Cheap ones sound awful. If it is 8 inches in diameter or more and is in a pretty big enclosure then it can produce good low frequencies. Some woofers are 4 inches in diameter and in an enclosure designed for it then it produces pretty good but not deep low frequencies.
A tweeter is a high frequency speaker. Cheap ones sound awful.
A crossover circuit is needed to feed low frequencies to the woofer and feed only high frequencies to the tweeter because high frequencies from a woofer sound awful and low frequencies will damage a fragile tweeter.
 

darren adcock

Sep 26, 2016
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Thanks. This is very helpful.

I would like to have the speaker in the same unit as the synth. 8 inches is doable, obviously smaller the better but I defo want the sub sounds.

I have just made a bass boost circuit (maybe this is what a low pass filter is). As was intending this to drive a bass speaker. and then make a treble booster for tweeter. Is this a good approach? or just look up crossover circuits.

I don't especially need it loud. At the minute I can hear it from 15 metres or so and that's enough. Just the amp part of the circuit doesn't fit my needs, or maybe the speaker doesn't.

That's interesting about the batteries and what they can drive, I wouldn't have thought about that at all. Thanks.

I could maybe have a separate speaker enclosure.

Darren
 

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Sep 24, 2016
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A crossover filter does not boost anything. It is a lowpass circuit for the woofer and a highpass circuit for the tweeter. At the frequency where they cutoff their levels are half power so combined they produce no boost and no loss.
 

darren adcock

Sep 26, 2016
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Is there any sound quality difference between the choke method or I.C method?
 

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Sep 24, 2016
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Is there any sound quality difference between the choke method or I.C method?
Are you talking about using discrete inductors and capacitors (choke method) for a crossover network connected to the woofer and tweeter speakers and want a comparison of using IC active filters driving separate amplifiers (IC method)?
Then active filters and separate amplifiers sound better (less distortion). But gEEtar players seem to want as much distortion as they can get to produce lots of Overdrive and Fuzzz. I think many gEEtar players are deaf to the awful high frequency distortion.
 

darren adcock

Sep 26, 2016
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hahahhahaa.... i'm one of them ex guitar as noisy as possible people.... but then always had synths as well so had the balance of hearing their richness of clarity.

That is the comparison I wanted yes. Thank you for your time here. I will get looking at circuits.
 

darren adcock

Sep 26, 2016
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haaaa, nah, disabled and unable to drive. However I did used to be in a band where we's just break metal objects whilst they were connected to piezo's, distortion pedals and amps. It was fun.But we all have bad ears now.
 
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