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Autophile · 10th October 2005, 19:19

Aseem,

Thats a nice essay on the output voltage.

Every headunit has a variable voltage output. Thats the only reason for controlling the loudness, your head unit is a preamp (act as a potentiometer). The stated voltage by the manufacturers is the maximum voltage the preamp stage of the headunit reaches at the full volume.

The high volatge output headunits and the line drivers for that matter are the easy way of making powerful systems using low quality amps. So the preamp stage has more gain and the final output stage of the amplifier does not have to work hard and hence manufacturer of the amplifier does not need to spend on expensive op-amps, powersupplies, caps and the heat sinking of the amplifiers.

The clarity part has nothing to do with the output volatge of the head unit its all about the components and the design which goes in designing the amplifier and the headunit.

The most expensive headunits like McIntosh, Denon etc work on 2 Volts that does not mean that they sound bad in front of Pioneers and Sony's and so on.

The noise related issues will be there in the car environment you cannot eradicate them. But you can control them by using good quality interconnects and cables. If one can afford go for the Fully Balanced System and it will take care of the noise.

A bad sounding headunit with 4V or 8V output cannot sound better than a good sounding headunit with 2V output.

The point here is that preamp out voltage should not be the only criteria for selecting or rejecting a headunit.

There are other more important things like S/N Ratio, D-A Convertor, Transport, Power Supply, Interface, Noise of DSP used etc...the list is just endless and probably at the end will come the ouput volts.

For your information one of the most expensive CD Players, Preamplifers and Amplifiers work on 2V.

Specs can never get you sound. If you buy 4v headunit and use it with cheap and poorly designed RCA cables don't even be under an impression that you are getting the best sound.

And moreover if the amplifier does not accept the 4V whats the use of 4V head unit..most of the times you are clipping the input stage of the amplifier which will pass the clipped signal to the output stage hence the whole system is driven into clipping.

By the way Aseem what is the setting you have finally done on the gain (input sensitivity adjustment) pot of your Pioneer 6100. And how have you done it? Because this is what matters more that the equipments and output voltage etc. etc.

If the preamp out of HU and input stage of amp in your system is not calibrated then there is no point of wasting breath by writing long posts.

This is from one of you links about preamp outputs :

"Op-amps:
In general, most op-amps cannot drive their outputs all the way to ground or to the regulated voltage. They may not be able to drive their output within 1.7 volts of either. This means that their output signal is limited to the regulated voltage (9 volts) minus 3.4 volts (1.7 * 2) equals 5.6 volts. Now remember that we are talking about peak-peak voltage output. The RMS voltage is only 35% of the peak to peak values. This means that the output from the op-amp will be limited to 1.96 (2) volts."

"The diagram below shows the relationship between the voltage output levels of each of the types of outputs. The white line would represent the voltage output produced by the op-amp powered by the switching power supply. The green colored waveform, the 4 volt output. The yellow, the 2 volt output.

NOTE:A piece of equipment that has a higher maximum output voltage is not necessarily going to sound better than one which is only capable of 2 volts output. The higher output will allow you to reduce the gains on your amp (or any down line signal processor) which will lower the noise floor of your system. If you are not having trouble with noise (alternator, hiss...), you may not benefit from the extra output voltage. You also need to realize that the voltage may be more than your amplifiers can handle. The extra voltage will not damage the amplifier but if the lowest sensitivity (gain setting) on your amp is 2 volts, and you drive it with anything more than 2 volts, it will cause your amp to clip*.

*This assumes that the gain setting is the voltage that will drive the amp to max power. Some amps are underrated and may have slightly more headroom and therefore will clip at a little higher power."

It is apparent you can Google well... I suggest you read the results before you post contents that contradict your statements.

10th October 2005, 19:19	#29 (permalink)
Autophile BANNED Join Date: Sep 2005 Location: New Delhi Posts: 948	Aseem, Thats a nice essay on the output voltage. Every headunit has a variable voltage output. Thats the only reason for controlling the loudness, your head unit is a preamp (act as a potentiometer). The stated voltage by the manufacturers is the maximum voltage the preamp stage of the headunit reaches at the full volume. The high volatge output headunits and the line drivers for that matter are the easy way of making powerful systems using low quality amps. So the preamp stage has more gain and the final output stage of the amplifier does not have to work hard and hence manufacturer of the amplifier does not need to spend on expensive op-amps, powersupplies, caps and the heat sinking of the amplifiers. The clarity part has nothing to do with the output volatge of the head unit its all about the components and the design which goes in designing the amplifier and the headunit. The most expensive headunits like McIntosh, Denon etc work on 2 Volts that does not mean that they sound bad in front of Pioneers and Sony's and so on. The noise related issues will be there in the car environment you cannot eradicate them. But you can control them by using good quality interconnects and cables. If one can afford go for the Fully Balanced System and it will take care of the noise. A bad sounding headunit with 4V or 8V output cannot sound better than a good sounding headunit with 2V output. The point here is that preamp out voltage should not be the only criteria for selecting or rejecting a headunit. There are other more important things like S/N Ratio, D-A Convertor, Transport, Power Supply, Interface, Noise of DSP used etc...the list is just endless and probably at the end will come the ouput volts. For your information one of the most expensive CD Players, Preamplifers and Amplifiers work on 2V. Specs can never get you sound. If you buy 4v headunit and use it with cheap and poorly designed RCA cables don't even be under an impression that you are getting the best sound. And moreover if the amplifier does not accept the 4V whats the use of 4V head unit..most of the times you are clipping the input stage of the amplifier which will pass the clipped signal to the output stage hence the whole system is driven into clipping. By the way Aseem what is the setting you have finally done on the gain (input sensitivity adjustment) pot of your Pioneer 6100. And how have you done it? Because this is what matters more that the equipments and output voltage etc. etc. If the preamp out of HU and input stage of amp in your system is not calibrated then there is no point of wasting breath by writing long posts. This is from one of you links about preamp outputs : "Op-amps: In general, most op-amps cannot drive their outputs all the way to ground or to the regulated voltage. They may not be able to drive their output within 1.7 volts of either. This means that their output signal is limited to the regulated voltage (9 volts) minus 3.4 volts (1.7 * 2) equals 5.6 volts. Now remember that we are talking about peak-peak voltage output. The RMS voltage is only 35% of the peak to peak values. This means that the output from the op-amp will be limited to 1.96 (2) volts." "The diagram below shows the relationship between the voltage output levels of each of the types of outputs. The white line would represent the voltage output produced by the op-amp powered by the switching power supply. The green colored waveform, the 4 volt output. The yellow, the 2 volt output. NOTE:A piece of equipment that has a higher maximum output voltage is not necessarily going to sound better than one which is only capable of 2 volts output. The higher output will allow you to reduce the gains on your amp (or any down line signal processor) which will lower the noise floor of your system. If you are not having trouble with noise (alternator, hiss...), you may not benefit from the extra output voltage. You also need to realize that the voltage may be more than your amplifiers can handle. The extra voltage will not damage the amplifier but if the lowest sensitivity (gain setting) on your amp is 2 volts, and you drive it with anything more than 2 volts, it will cause your amp to clip. This assumes that the gain setting is the voltage that will drive the amp to max power. Some amps are underrated and may have slightly more headroom and therefore will clip at a little higher power." It is apparent you can Google well... I suggest you read the results before you post contents that contradict your statements. Last edited by Autophile : 10th October 2005 at 19:22.