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Probable a stupid question.......but what does a preamp do??


jeff spicoli
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I might have a chance to get a well regarded solid state preamp but began to think that I really dont know what they do? should I save my money for other gear? How do I know if I even need one? I googled it and came up with tons of technical answers but i'm not very technical. I'm saving my money for a pair of Dynaco Mark III's and would I need a preamp for the Dynaco's?

I'm used to just plugging the speakers into the reciever, hooking up the cd player or turntable and listening to the music. Tubes and preamps are all new to me.

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If you took your receiver and split in to two seperate sections, you'd have an amp and a pre-amp. The amp amplifies the sound to your speakers. The pre-amp does all the switching. You plug all your components into it, it receives the signal for your components ans sends it to your amp.

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Hey Jeff, no stupid questions around here, just stupid people who don't ask questions! [;)]

A Receiver is a Pre-amp/Processor and Amplifier in one unit.

If you know what an amplifier is, well a "preamp" does everything else. Some are very simple and others have many, many features.

Preamps have volume controls, bass and treble controls, balance control, input selection and so on. They need an amp to produce sound.

An integrated amp is a preamp and amp all in one, also. A processor and amp are integrated into one unit.

I hope this helps,

Dennie

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If I get the Dynacos which are obviously tube amps....do I need to get a tube preamp? or will the ss work with tubes?

SS (pre) will work with tubes. Some perfer it, some don't. But, at least you can try it out for yourself and see what you think.

Dennie

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Jeff : in addition to what others have already mentioned: preamps provide gain and impedance relationship matching for low level signals. What is often not mentioned is that they can sometimes be less of a help than more. This is what I mean by that: many modern sources, such as CD, already provide both an adequate line-level voltage and suitable output impedance to drive an amplifier directly. Some modern Dynaco modifications include provision for installing a volume control directly on the amp, such as the very well-known ST-70. This volume control replaces the fixed input resistor, and makes the need for a preamp (subjectively) not necessary in terms of the need for extra gain. In fact, most people use their preamps to attenuate the already-adequate voltage provided by their CD players. Some need a preamp for switching and for voltage gain for low level phono cartridges. Edit: to add to this, I didn't have time to finish earlier: if an amplifier's input sensitivity, which is what is required from an input signal for full output, is in the approximately 1.5V (approx) to sub 1V range, things are usually fine. Some amps have greater gain requirements, though, and benefit from the extra boost provided by a preamp. The other issue has to do with the complexity imposed by an increase in circuitry and, in the case of an active line stage (preamp), the need for a power supply with good power supply rejection, which with high sensitivity speakers like Klipsch, can be problematic in terms of undesirable residual noise.

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Erik makes a very good point. My Oppo CD/DVD player has a built in gain, so I can bypass the "pre/processor and hook it directly to an amp and control the volume that way. Less "gear" in the chain, the better the sound should be.


Dennie

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My simple approach has always been that while differing sources present a variety of output levels, amps want to see a single level. The preamp levels the playing field...in addition to providing the switching, volume, and such previously mentioned.

Dave

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Dave: if I may add to what you said: if one wants to have source signals attenuated equally so that the output is the same regardless of source, it's often necessary to pad the input into the preamp -- either by fixed or variable resistive networks - in such a way that the higher gain sources are padded down to approximate the weaker inputs. Some preamps have input level controls to achieve this, but people also use in-line attenuators on interconnects to achieve say a 6dB-12dB reduction in gain. The other way to do this, of course, is by increasing the output strength of the source, which in my case is by increasing the gain of my phono preamp to that of a stronger, line-level signal.

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Dave: if I may add to what you said: if one wants to have source signals attenuated equally so that the output is the same regardless of source, it's often necessary to pad the input into the preamp --

Not going to question your personal experience as I just don't do that, but I have never experienced this with standard equipment either professionally or in the hobby.

I'd be curious as to specifically just what type of sources you are referring to?

Dave

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