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Post by rockman85 on Nov 19, 2019 13:10:28 GMT -5
What I have come to understand with amplifiers and their output wattage is that for a given voltage output on the preamp, the amplfier will channel x amount of wattage depending on its gain. Most Emotiva amps seems to be 29db gain amps. So an amp with a capability of 100 watts, and an amp with the capability of 1000 watts will output the same power if the gain of the two amps is the same, also assuming the smaller amp is not in clipping range (aka above 100 watts).
So my question is this: How do we know the amount of voltage needed to reach the maximum power output of an amplifier, and what spec do you look for on the preamp?
In other words, if I want to to buy a preamp that has the potential to take my amp to its maximum, what number should I look for, and how do I know what I need that number to be?
I know that with 1000 watts you would deafen yourself with most speakers, I am merely curious about how all this stuff works....
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DYohn
Emo VIPs 
Posts: 18,491
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Post by DYohn on Nov 19, 2019 13:24:50 GMT -5
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Post by rockman85 on Nov 19, 2019 14:44:01 GMT -5
I spent the last hour doing all the math, very helpful and informative. And I can also see now that this spec is called "input sensitivity" on Emos amps. So 2.1v is what they need, to get the most power output. Thanks! |
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Post by rockman85 on Nov 19, 2019 14:49:31 GMT -5
So how does that translate to the XSP-1, the only thing I can find in the manual is the gain structure.
Gain structure:
Nominal output level: 0 dBV (1 V).
Nominal gain (with Volume set to “0”): 1.
Maximum gain: +12 dB.
So its 1 volt at 0db, so how many more volts is +12db?
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Post by rockman85 on Nov 19, 2019 14:54:59 GMT -5
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Post by AudioHTIT on Nov 20, 2019 0:41:34 GMT -5
... and still 6 dB of gain on the preamp, though it can clip too, seems like a good place to be. Generally things should be getting pretty loud by 0, and you’ve now applied 4 times more power beyond that. |
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Post by pedrocols on Nov 20, 2019 10:51:23 GMT -5
Sometimes the use of a preamp is unnecessary unless you want to add coloration to the sound.
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KeithL
Administrator 
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Post by KeithL on Nov 20, 2019 11:49:40 GMT -5
You are quite correct... Two power amps with the same gain will deliver the same output level with the same input voltage...
But the more powerful one will be able to be turned up higher, and deliver more output power, before it starts to distort. (Note, though, that power is related to the square of the voltage... so, to get a 1000 watt output, compared to a 100 watt output, you only need a little over 3x as much signal voltage going in.)
I've already seen several great answers... so I'll just offer a very general one. While there is no actual standard for this sort of thing - most consumer audio gear is designed to work with most other audio gear.
So most preamps or processors are designed to work with most power amps and vice versa.
So, in general, with a few rare exceptions.... - most power amps have an input sensitivity (the amount of signal voltage they need to reach full power) of somewhere between 1V and 4V - most preamps are capable of delivering at least that much voltage (and often quite a bit more if asked to)
- most preamps will have no problem driving most power amps to full output level
(and, even though the "preamp outputs" on some AVRs may have a lower "rated output voltage" most of them have a higher "maximum output voltage" and will still be OK)
The same holds true for the line level inputs on powered monitors (which are just an amplifier in a speaker).
The most common exceptions to this are.... - portable sources like smart phones and tablets (many of these don't deliver enough output voltage from their analog outputs to drive a power amp or powered monitor directly to full output level)
- some tube gear; especially vintage models
(some tube preamps have a limited ability to deliver enough voltage into the impedance offered by the inputs on some modern equipment) - so called "passive preamps"
(since most of these reduce rather than boost the level of the signal coming from the source, what's left may not be enough to drive a power amp or powered monitor directly)
What I have come to understand with amplifiers and their output wattage is that for a given voltage output on the preamp, the amplfier will channel x amount of wattage depending on its gain. Most Emotiva amps seems to be 29db gain amps. So an amp with a capability of 100 watts, and an amp with the capability of 1000 watts will output the same power if the gain of the two amps is the same, also assuming the smaller amp is not in clipping range (aka above 100 watts). So my question is this: How do we know the amount of voltage needed to reach the maximum power output of an amplifier, and what spec do you look for on the preamp? In other words, if I want to to buy a preamp that has the potential to take my amp to its maximum, what number should I look for, and how do I know what I need that number to be? I know that with 1000 watts you would deafen yourself with most speakers, I am merely curious about how all this stuff works.... |
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Post by rockman85 on Nov 20, 2019 12:40:15 GMT -5
... and still 6 dB of gain on the preamp, though it can clip too, seems like a good place to be. Generally things should be getting pretty loud by 0, and you’ve now applied 4 times more power beyond that. Of course, just trying to get a handle on the math and engineering side. I don't even turn my Stealth DC-1 past -15 usually. |
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Post by rockman85 on Nov 20, 2019 12:44:03 GMT -5
The most common exceptions to this are.... - portable sources like smart phones and tablets (many of these don't deliver enough output voltage from their analog outputs to drive a power amp or powered monitor directly to full output level)
Incidentally, this problem right here is what started my audio journey. Knowing absolutely nothing at the time, I was trying to feed an old 80's Sony integrated amp with my smart phone with a 3.5mm jack to RCA adapter. I initially thought that the amp was too old or something because it would not get loud enough. |
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