If I'm connecting a preamp to my tube amp, I want the preamp output impedance to be at least 10x times the input impedance of my amp? Is that correct?
Is the greater the difference the better?
Thanks.
Is the greater the difference the better?
Thanks.
It must be the load impedance (the amp) greater than the source impedance (The "pre"), in you case, the most of the output voltage from the preamp will be lost in its internal impedance. In the better case, the impedances must be equal, so the best POWER transfer between them will be true.
I think you mean 10x times less the input impedance of your amp.
And yes, the greater the better.
By the way, this holds for everything in audio systems. Loudspeakers etc...no impedance matching is used here !
And yes, the greater the better.
By the way, this holds for everything in audio systems. Loudspeakers etc...no impedance matching is used here !
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No, you definitely don't want that. The aim here is minimum signal damage, not maximum power transfer.
Not necessary. The more non-linear and frequency dependent are output and input impedances, the higher mismatch you need. But when they are linear and frequency independent in the frequency band it is the best to have them of equal impedances.
Loosing power on impedance mismatch you have to amplify it back adding more distortions. But sometimes it is easier to make more linear gain than more linear input/output resistances, especially when you don't know what kind of signal source will be used with your power amp, or what kind of load will be used with your preamp.
I agree. I have the impedances as matched as I can. Particularly, in speaker systems impedance matching IS definitively important.
No
A speaker is not a linear resistance. It even produces negative resistance due to induction voltage from the voice coil movements.
With impedance matching you get worse damping of the speaker und more distortion.
Impedance matching is only useful in RF circuits and antennas.
A speaker is not a linear resistance. It even produces negative resistance due to induction voltage from the voice coil movements.
With impedance matching you get worse damping of the speaker und more distortion.
Impedance matching is only useful in RF circuits and antennas.
There may be some confusion here about "impedance matching" and the difference between maximum efficiency and maximum power transfer. Impedance matching for a speaker means a DF of 1, and boomy bass unless the speaker was specifically designed for this unusual situation. People often loosely talk about impedance matching, when what they really mean is "using the correct impedance" - usually a significant mismatch.
Impedance matching for a line level connection would require unusually low amounts of stray capacitance or low and linear impedances at both ends. As Wavebourn says, generally easier to go for even lower impedances at source and high at load, then you don't have to worry about impedance linearity so much.
Impedance matching for a line level connection would require unusually low amounts of stray capacitance or low and linear impedances at both ends. As Wavebourn says, generally easier to go for even lower impedances at source and high at load, then you don't have to worry about impedance linearity so much.
I never saw such a thing. If I´m not wrong, the speaker is always a positive resistance, if not, a negative R any amplifier will oscillate. The impedance varies, but never go negative.
In other hand, I want high fidelity from an audio set, I don´t care if it is bassy or not. To adjust the curve response there exist tone controls.
Salu2 para to2.
You can't correct 'one note bass' from the underdamped bass resonance simply by using tone controls. The bass resonance is narrow, tone controls are wide. 'One note bass' is not high fidelity.
A loudspeaker will have positive resistance; it does not generate energy, although it may store it for a while.
Yes, you are right, but I like music "as is". Rarely I want to correct the music as it comes to me, if I could eliminate all kind of resonances mechanical, electrical or acoustical, I would do. I hate resonant bass like some equipment some people put in some cars, that appear to run bouncing. I like music with bass, middle, and treble well balanced, and in general as the author made it, and in the original format (CD, LP, MP3, etc).
What you tell is like this people that add salt to meet before start eating. Why? If the cooker believed it is well seasoned.
Why to use false bass resonances? If in some instances, you do not want to use it, how do you eliminate them?
Sorry, is my personal point of view.
When you add salt before eating it does not resonate on the plate. But when you equalize frequency response electrically you don't damp the resonance, and anyway the speaker will resonate on this frequency. Waterfall graphs are very revealing. Electrical damping works well on frequencies on which the whole oscillating system is well controlled electrically. But again, damping electrically you have to think about linearity of output resistance of the amp that damps oscillations of speaker cones, so you want as low as possible output resistance if it is non-linear.
OK, but it increments your arterial pressure unnecessarily.
The only place where I like resonances is in tuned circuits in RF or antennas (Aerials), but I dislike them in audio playback equipment.
Right.
It is easy to prove that low Q resonances are more audible because the higher is Q the less of notes excite the resonance. But low Q resonances when equalized electrically are less audible than high Q resonances equalized the same way. It is one reason why designers tend to get output resistance of power amps less, to damp mechanical resonance. Further reduction of output resistance of the amp is needed when it's output resistance is non-linear, and reducing it further designers reduce amount of distortions generated by amp loaded on speaker. So, DF of 100 and higher is not needed for the speaker per se, it is needed for the amp.
It is easy to prove that low Q resonances are more audible because the higher is Q the less of notes excite the resonance. But low Q resonances when equalized electrically are less audible than high Q resonances equalized the same way. It is one reason why designers tend to get output resistance of power amps less, to damp mechanical resonance. Further reduction of output resistance of the amp is needed when it's output resistance is non-linear, and reducing it further designers reduce amount of distortions generated by amp loaded on speaker. So, DF of 100 and higher is not needed for the speaker per se, it is needed for the amp.
Dave, please help me because I couldn´t understand some fact. Suppose your speaker in the enclosure has some resonance about (say) 430Hz. Each time that a player generates the "La" tone at 440Hz, your system will boost that note, but it will appear to the ears as a 430Hz note, because of resonance. But happens that 430Hz does not exists in any normal musical instrument (I am not musician, so I may be wrong), so it resonance will appear as a severe distortion I believe.
If I am right, so which is the advantage of maintaining such resonance?
Sorry if i am wrong, I am not a musician, and also if my english is not good !!!
If I am right, so which is the advantage of maintaining such resonance?
Sorry if i am wrong, I am not a musician, and also if my english is not good !!!
430/440Hz is much higher in frequency than a bass resonance.
A note only has a single frequency if it lasts for ever. A real (shorter) note is more complicated. If a linear system has a constant input at 440Hz only, then it can only generate a 440Hz output. A varying input will occupy a range of frequencies. Similarly, a resonance can only ring at its own resonance frequency but because the amplitude is exponentially decaying the spectrum will be wider than this. Things are not as simple as your question suggests. Fourier theory is the thing to look at.
In audio we usually want to avoid resonances, hence we avoid impedance matching.
Your English is fine!
A note only has a single frequency if it lasts for ever. A real (shorter) note is more complicated. If a linear system has a constant input at 440Hz only, then it can only generate a 440Hz output. A varying input will occupy a range of frequencies. Similarly, a resonance can only ring at its own resonance frequency but because the amplitude is exponentially decaying the spectrum will be wider than this. Things are not as simple as your question suggests. Fourier theory is the thing to look at.
In audio we usually want to avoid resonances, hence we avoid impedance matching.
Your English is fine!
Till I know, resonances happens when underdamped systems, and then generally occurs when impedances are not matched, like al LC filter.
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