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Master_Scythe

Old 3 way speakers

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Thank you, brb with more....

 

Oh, yeah, thats a good one, I was thinking of another less complex, but still revealing pages from the SAE. I think they have put them behind closed doors now.

Edited by GlennsPref

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For anyone building a system from scratch, please!

 

Speakers first, at the end of the day they will have the biggest influence on the sound and what you can achieve, get the very best you can within budget and what sounds best to you with the types of music you listen to. Also pay attention to the room they will reside in, the room has maybe an equal or even bigger influence.

 

Amp second.

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It's bloody lunchtime, here's what I've got so far....

 

 

esr is "effective series resistance", but it's dependant on frequency.

And may be compensated for with resistance in parallel.

 

(note, I find it difficult to explain with out diagrams, and I'm shit at formatting ASCII art, sorry.

I've got a scanner downstairs, But I've never hooked it up to see if it works. Maybe now is a good time to start.)

 

One way you can safely test, is to get a large/full-range speaker, not a dedicated sub,

 

mount it to the outside of the box, seal up all other the holes for now, now you have easy access to the terminals.

 

Grab a hand full of filters (caps, resistors and inductors,) and carefully insert one at a time and listen for the difference.

 

WARNING, you can fry your amp if you touch/short-circuit the wires coming from the amp. always power down before making changes.

Current, like water, will always follow the path of least resistance.

 

you can get a cheap impedance meter and pink noise generator kits from electronics stores.

 

Altronics had a sign wave generator K2549, handy for burn-in tests.

ref http://www.altronics.com.au/index.asp?area=prod&grp=429

 

And my Altronics Imp meter is not listed any more (I can't find it), but it's kit number is K2550.

 

lcr meter kit....http://my.integritynet.com.au/purdic/lc-meter-project.htm (nice, but Not personally tested)

 

esr meters....http://members.ozemail.com.au/~bobpar/esrmeter.htm

 

 

A crystal radio kit is a great way to start experimenting with networks and filters.

 

back to esr and impedance matching.....

 

when you add a filter, the effective ac impedance of the (now it's a network) load the amplifier sees may/will change.

 

Thus, with a lower impedance the amp will run freer/more easily. and conversely,

if the impedance is increased the amp will have to work harder to get a comparable volume from the load/speaker.

 

So low resistance means the box will sound louder, and it is, but the amp is getting close to free-wheeling, and may burn itself out.

A short circuit will do this in a moment, no load= no resistance/impedance.

 

This is why you need to match the load to the amp (impedance matching)

 

feedback = Reflected load and resistance back to the amp. = reflected impedance

 

Now if the box has a crossover in it and it is not damaged, if you need to, just replace the speaker with another, rated equally.

 

If you up the wattage capability of the speaker it will change the sound, because the sensitivity of the speaker is changed too.

 

sensitivity=how easy the speaker moves off it's centre point, for want of a simple example.

 

Now, we also have the feedback the amplifier is seeing, that is, as said above, sensitivity and damping, and resonance all affect what the amplifier is capable of delivering, with out being muffled (or exaggerated) by any one (or a combination) of those variables.

 

It's all physics, we have electrical, mechanical and acoustic properties to take into account, A network.

 

Kirchhoff's voltage and current laws

Current: A law stating that the total current into a junction equals the total current out of the junction

Voltage: The sum of the voltage drops around a closed loop equals the source voltage. But that's not all......bored yet?

 

It's a big balancing act!

 

Phase cancellation.....The relative displacement of time-varying waveform in terms of it's occurrence with respect to a reference.

 

Here we may imagine a water tank up high, with 2 pipes of equal length and diameter, one goes to the basin tap, and the other goes to a shower head, also with a tap. Nothing unusual here, right.

 

Now, if we turn both taps to fully open, we will probably get more litres/second from the basin tap, than from the shower, because of the restriction placed on the shower tap by the shower head (rose).

 

But we should be able to adjust either tap to influence the litres/sec of the other.

 

Think of the cold/hot surge when showering when someone uses the water elsewhere in the house.

 

So, this is what happens to the electrical signal as it passes (or not) through a filter, or a range of filters.

 

We can compensate for these phase cancellations, resonances by further filtering. But it gets more complex the further you go.

 

And as stated some place above, more is not always better. It's expensive, sometimes uneconomical and nearly always adds distortions of some kind somewhere.

 

Co-efficiency and coupling, how easy the signal is transmitted to and from the source and load.

Think, internal and external coupling wires.

 

CMRR, Common Mode Rejection Ratio, or simply "phase cancellation" in a device (op-amp)

 

Ohm's law, current is directly proportional to voltage and inversely proportional to resistance.

 

Watt's Law, relationships of power to voltage, current and resistance.

 

Q (quality factor), The ratio of reactive power to true power in a coil(speaker, transformers and inductors) or resonant circuit (X-O or filter).

 

Any questions?

 

Regards Glenn

Edited by GlennsPref

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a

 

But it seems my amp is far too smart for that, as it didnt care, and the speaker certainly wasnt 'sucking' instead of 'pushing' the cone. Damn new technology, lol.\

are you really that fucking thick.

 

 

seams like it....... please dont touh anything audio related anymore.

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Dude, no need for that.

 

We all start somewhere, not everyone can be as good as you are from birth.

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a

 

But it seems my amp is far too smart for that, as it didnt care, and the speaker certainly wasnt 'sucking' instead of 'pushing' the cone. Damn new technology, lol.\

are you really that fucking thick.

 

 

seams like it....... please dont touh anything audio related anymore.

 

 

If its that important for you to get in my head, I was tired and my mind thought "whats that old trick with car speakers? oh yeah, 9v battery"; for some reason this made my mind think DC output, which as i corrected myself in my next post, is obviously not the case.

 

I understand audio to the point of being able to set up basic home theaters, install full car audio setups, and understand frequencies when it comes to actually listening to them.

 

Anything else is still a learning experience for me (such as 3 way speakers and working out impedance when crossovers are involved).

 

anything else you wanna attack me for so i can RTM or shall we just let this rest?

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