Think of it as an input switcher with a volume control :-)
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there is no active gain in a passive preamp. it's just an attenuator with switching capability. so you can select the input source and turn the volume down but not up. since there is no active circuits, many believe the sound to be of utmost transparency but there may be impedance mis-matching and lack of dynamics if cable runs are long as the signal strength will attenuate down the cable path.
A passive pre-amp doesn't amplify the signal. It only attenuates the signal from the source.
A "Passive pre-amp" can come with one or more inputs but the use of the name "passive pre-amp" is inappropriate. Your impression is correct. It is a passive 'line stage', or in the case of a single input its simply an inline volume control/attenuator.
Actually "preamplifier" Means, "an amplifier before" something else, just as "pre-driver" means a transistor or tube that drives (provides a gain stage) before an output stage. Obviously- A preamplifier would be placed BEFORE a power amplifier, and provide gain for signals too weak to drive an amplifier on their own. Having a phono stage has nothing to do with it being termed a, "preamplifier", as a phono stage is a pre-preamplifier in and of itself(providing gain and EQ to industry standards). Whether it provides gain or not has EVERYTHING to do with the term. No unit can correctly be termed, "passive" and "preamplifier" at the same time, as passive connotes, "not active," as in, "no active circuitry." That would be an oxymoron(like "jumbo shrimp", "freezer burn", "deafening silence"). Most signal sources(CD players, tuners, tape decks, etc.) can provide sufficient line-level voltage(1.5V to 2V+) to properly drive the amplifier of average gain/sensitivity to a satisfactory output level(subjectively). HOWEVER: recorded material varies widely in the level with which it's recorded. While my CD player will put out up to 2.5V balanced, some material I have(some Sheffield Labs, MFSL) was recorded at a level so low that it is not listenable without gain(thus my giving up my Placette Passive Linestage and returning to active pre-amplification). "Linestage" connotes providing the ability to switch between sources, and again- to contain circuitry that provided voltage/current gain to the signal(which necessitates a power supply) precludes it from being, "passive." Tone controls/equalizers can be passive or active, again depending on whether they contain a power supply(active circuit) to provide gain within their bandwidth, or all passive(resistors, capacitors, inductors) components. Some passives have a power supply to facilitate a remote control, but there's no connection within the signal path. I'm certain this little treatise will generate a multitude of replies by those that enjoy engaging in semantic gymnastics. Of course: The dictionary has been ammended to contain things like, "ain't" and "irregardless" to cater to those that know no better. I'll pass on that game as well.
I want to thank each one of you for their response and explanations. Very informing! Although, I did not mean to start a debate. Each one of you has made a good point, especially Unsound. Yes, Herman, I agree with you: that general term is used so often by the manuf.& Audio media, that, when one hears or reads the desc. "passive",without explanation, the uninformed is left with a vague understanding.
Herman, you are wrong. A real preamp contains a phono stage. Look at Audio Research for example. None of their linestages are called a preamps unless there is a phono stage.
From the Audio Research Data Base:
Preamplifier is the name applied to the first amplifier in the audio chain, accepting inputs from low output sources such as CD players, tape recorders, turntables, etc. The preamplifier increases the input signals from tape-level, for instance, to line-level.
line stage (ln stj)
A line stage is a preamplifier without a phono section.
C'mon, guys, this is silly . . . terminological snobbery does not endear people to our hobby. I'm personally happy with the term "passive preamp", but it's not because of any ignorance of what's going on inside the box. It's for the same reason that I don't correct somebody if, for example, I ask for a Kleenex and somebody hands me a box of Puffs.
The term "preamp" in audio, for at least 50 years, has most often meant "the thing with selector knobs and a volume control that goes between sources and power amplifiers". So thusly, a "passive preamp" is most commonly understood to be one of these things, that performs its functions with passive components only . . . the big indicator being that it has no power cable or batteries. They are for "line-level" (IHF 250mV) sources only, and generally work best in systems that have high gain power amps and/or sensitive speakers.
A "preamp" does not require a phono stage to keep its name . . . this has been true for many years. Remember that tape-playback preamps at one point migrated from the "preamp" to the tape deck? Yet nobody demands that we call a Revox A77 an "integrated deck-preamp" or whatever. Likewise, if somebody owns a "passive preamp", and they want to play records . . . they must ask for a "phono preamp" or a "phono stage" if they want the proper thing. Simply asking for a "preamp" will most likely not do.
I think that even those who scoff at the term still know exactly what one is . . .
Rwwear, if you look at their website they lump all of them in the category preamplifiers and all have preamplifier in their name.. Even if they did describe them as you say, which they don't, just because AR calls them one thing does not make it so. Calling a pig a horse does not make it a horse.
Dopogue, saying "pre means it comes before" doesn't mean it describes everything that comes before. If I say something is in the pre civil war era it is understood that is the time leading up to the war, not everything that ever happened before; AND it is not the war that came before the civil war as some here would have you believe.
Kirkus is correct. It is a silly argument. It is well understood what it means. It is the box that goes between the source(s) and the power amp. It can be as simple as some jacks for in/out and a volume control and you can add what you want from there; input selector, active buffers, active gain stages, tone controls, phono stage, balance control, loudness function, etc.
Not true Herman, only passive devices are used to attenuate. A preamp or linestage amplifies the signal. Therefore they are actually amplifiers in their own right. Which is the reason a passive device lacks dynamics in most instances. By the way, we had a good laugh at the stereo shop where I work about your comment that a preamp is called so because it comes before the amp. And yes, technically a preamp is not a preamp without a phono stage. Most people call linestages preamps including myself but they are not. You can call them bicycles or anything you want but that doesn't make it correct.
ARC(see the LS-26 page), Lamm, Levinson, Edge, Van Alstine, Herron, Joule-Electra, Conrad-Johnson, Aesthetics, Musical Fidelity, Ayre (to name a few) If you visit the sites of the manufacturers I've named: You'll note they ALL refer to their preamplifiers AS SUCH, whether the have a phono section or not. Most don't even offer one as an option. If the people that build them can call them preamps: I suppose I can as well.
Sorry Mr. Wear, you are incorrect. Here's a lesson for you and your giggling buddies at the stereo shop.. The signal coming out of a typical CD player or other line level source is enough to drive most amplifiers way past clipping. Therefore, even an active preamp in most systems outputs a signal that is less than the input signal at reasonable volume levels.. This is called attenuation. I would think someone who works in a stereo shop would know this.
Amother lesson for you. Some active preamps at maximum output do not amplify the signal. They have a gain of 0db and sometimes just a bit less. The active stage is used as a buffer between the source and the amp. To call them preamps would then be incorrect by your definition
As far as I know there is no legislative body that decides what words like preamp "technically" mean. Why are you so adamant it must contain a phono stage? Even your example of AR as a refrence fell on it's face since they call all of their's preamps whether they have a phono stage or not. If I and many others prefer the definition that it is the device before the amplifier that contains the volume control then how can you prove us wrong?
I will venture a guess that you are old enough that you remember when CDs did not exist. If not, here's another lesson for you. In that era most if not all preamps did contain a phono stage. When CDs caught on and many had only a CD player as a source manufacturers came out with preamps that did not have a phono. To distinquish them from those that do they coined the term line stage and some started calling those that did have phono a full function preamp, but if you like the definition that a preamp is the amplifier before the amplifier then line stages certainly fit right in.
I am trying to be nice Herman but obviously you are one of those people that will not admit it when they are wrong so let's stop even discussing the subject. You can be right if you say you are. But ARC as an example names all of their preamps with a phono stage with the prefix SP for stereo preamp as in SP-9, SP-10 and so forth. They use the prefix LS for their line stages which contain no phono stage as in LS-9, LS-16 and so forth. I use ARC as an example but there are many others and the ARC Data Base is not affiliated with ARC anyway.
As I stated earlier, you can call a linestage a preamp if you want. A lot of people do including myself.
0db is wide open on many preamps and receivers that have a numerical readout.
Mr wear, from their official website as I pointed out in a link in a previous post.
MP1 Multichannel Preamplifier
SP17 Class-A Full-Function Vacuum Tube Preamplifier
LS17 Class-A Vacuum Tube Stereo Line Preamplifier
LS26 Class-A Vacuum Tube Stereo Line Preamplifier
If you care to notice they call every one of these a preamplifier.
I accept your apology.
OBVIOUSLY- The manufacturers(with VERY few exceptions) consider a linestage that CAN provide gain(requires a power supply or "active" circuit) to a signal passed through it(AMPLIFY said signal), whatever the source, a "PREAMPLIFIER." A linestage with ALL passive components in the signal path (resistors, capacitors, inductors), and no connections to a power supply/active circuit, a "PASSIVE LINESTAGE." Wasn't there a song titled, 'How Long WILL This Go On?' Maybe I'm thinking of, 'How Long HAS This Been Going On?' Yeah- that must be it! LOL!!