Seems like a simple question, but is it?
Consumer line level is specked at -10 dBv.
Is that nominal, peak, 10dB below peak???
It seems like developing full output power with -10 dBv is a bit aggressive.
Consumer line level is specked at -10 dBv.
Is that nominal, peak, 10dB below peak???
It seems like developing full output power with -10 dBv is a bit aggressive.
Not sure I understand your question. -10dBV is of course 10dB below 1V, around 300mV.
Was that the question? What type equipment are you talking about?
If this is a power amp, full power from 300mV is a bit sensitive but not totally unheard of.
Jan
Was that the question? What type equipment are you talking about?
If this is a power amp, full power from 300mV is a bit sensitive but not totally unheard of.
Jan
I clearly understand the dB units, -10 dBv is 316 mV RMS. My question centers on a tube power amp specifically, but is more general for any power amp in a consumer application. I agree that 316 mV RMS for full power is hot, and that raises the original question.
from : en.wikipedia.org/wiki/Line_level
quote:
Expressed in absolute terms, a signal at −10 dBV is equivalent to a sine wave signal with a peak amplitude (VPK) of approximately 0.447 volts, or any general signal at 0.316 volts root mean square (VRMS).
:unquote
For tubes 300mV rms is normal ... and many are more sensitive than this .
The quick reason is that you would want as little negative feedback as needed , maybe not at all . As opposite to solid state .
The quick reason is that you would want as little negative feedback as needed , maybe not at all . As opposite to solid state .
I am designing a driver board for a dynaco MK4. Doing it to learn tubes, try something a bit different and hopefully try to improve overall performance (whatever that means). Yes my question quickly encompasses forward and FB gain optimization. The original MK4 has 23 dB of closed loop gain giving a full power input sensitivity of about + 2 dBv or 1.3 VRMS. Way different from the consumer line out of -10 dBv. The VTA driver board for the ST70 is much closer to -10 dBv full power input sensitivity. So what is right? I would like to be able to use the volume control of my Kenwood amp in a practical way.
It's a mess, really.
CD players usually have a maximum sine wave level of 2 V RMS, so 2 sqrt(2) V peak. Older equipment usually has lower levels.
Moving-magnet phono amplifiers often have a gain of about 40 dB at 1 kHz, so with a typical sensitivity of 5 mV at a 5 cm/s nominal level, the nominal output level is 500 mV RMS assuming sine waves. No idea what the maximum level is, though.
CD players usually have a maximum sine wave level of 2 V RMS, so 2 sqrt(2) V peak. Older equipment usually has lower levels.
Moving-magnet phono amplifiers often have a gain of about 40 dB at 1 kHz, so with a typical sensitivity of 5 mV at a 5 cm/s nominal level, the nominal output level is 500 mV RMS assuming sine waves. No idea what the maximum level is, though.
If I ever finish designing and actually building this board I plan to share the design and test results with the community.
Potentiallyincorrect,
Where did you read that the consumer line level is -10dBV?
The answer to that might reveal the context, the vintage, etc.
Please provide a link to the document(s).
Line level used to mean the line input to a preamp or to an integrated amplifier.
It was not intended to mean a power amplifier input.
It was not intended to mean a magnetic phono level input.
Typically, over time, line level specifications were applicable for tuner output, phono preamp output, and CD player output, as they were applied to a preamp line inputs, or to an integrated amplifier inpus.
Most of those signal sources had more than -10dBV output . . . which is why preamps and integrated amplifiers had guess what, . . . A volume control.
I hope that explains it.
The above are just my opinions.
Would someone else on this thread please confirm that?
Thank you!
As I often say: "Standards are such a wonderful thing, that everybody has his own standard"
-10dBV is someones standard, but whose?
Where did you read that the consumer line level is -10dBV?
The answer to that might reveal the context, the vintage, etc.
Please provide a link to the document(s).
Line level used to mean the line input to a preamp or to an integrated amplifier.
It was not intended to mean a power amplifier input.
It was not intended to mean a magnetic phono level input.
Typically, over time, line level specifications were applicable for tuner output, phono preamp output, and CD player output, as they were applied to a preamp line inputs, or to an integrated amplifier inpus.
Most of those signal sources had more than -10dBV output . . . which is why preamps and integrated amplifiers had guess what, . . . A volume control.
I hope that explains it.
The above are just my opinions.
Would someone else on this thread please confirm that?
Thank you!
As I often say: "Standards are such a wonderful thing, that everybody has his own standard"
-10dBV is someones standard, but whose?
re: Post # 12 . . .
That is a wonderful document, as far as it goes. However, it is incorrect for most consumer CD player outputs . . .
Most CD players, and external DACs for CD playback that use Power Mains (not batteries):
They have a line output specification of about 2.0Vrms to 2.1Vrms at full scale DAC output.
2.1Vrms is about 3.0V Peak.
That is far more than -10dBV (316mVrms, 447mV Peak).
For the actual output of such CD players, and outboard CD DACs, the voltage is dependent on the actual CD recording level.
Example: Many Chesky CDs, have peak outputs that are about -10dB referenced to Full Scale of the DAC.
Just Saying
That is a wonderful document, as far as it goes. However, it is incorrect for most consumer CD player outputs . . .
Most CD players, and external DACs for CD playback that use Power Mains (not batteries):
They have a line output specification of about 2.0Vrms to 2.1Vrms at full scale DAC output.
2.1Vrms is about 3.0V Peak.
That is far more than -10dBV (316mVrms, 447mV Peak).
For the actual output of such CD players, and outboard CD DACs, the voltage is dependent on the actual CD recording level.
Example: Many Chesky CDs, have peak outputs that are about -10dB referenced to Full Scale of the DAC.
Just Saying
I think the question was about what the standards are. Whether manufacturers play by the rules or not is another topic for discussion. 🙂
Again: "Standards are such a wonderful thing that everyone has his own standard"
Standard Wheels: 12", 13", 14", 15", . . .
Get it?
Standard Wheels: 12", 13", 14", 15", . . .
Get it?
Thanks all!
I will take some measurements of my preamp ( Kenwood basic C1 ) typical or not and report back. Things like knob position with 0dB gain and gain with knob fully clockwise. I will excite the input with -10 dBv.
I will take some measurements of my preamp ( Kenwood basic C1 ) typical or not and report back. Things like knob position with 0dB gain and gain with knob fully clockwise. I will excite the input with -10 dBv.
After reading the thread subject title again (dBv in for full power out??), it seems like the real question being asked is what is a reasonable "sensitivity" figure for a power amplifier; that is, what input level is required to deliver full output power.
Most power amplifiers, whether tubed or solid state, will have a sensitivity specification in the range of 1 to 1.5 volts RMS for full output. As examples, the Dynaco ST-70 power amplifier had a sensitivity spec of 1.3 volts in for 35 watts out; and the modern NAD C298 solid state power amplifier specifies a sensitivity of 1.43 volts in for 185 watts out. Clearly, these two amps have different closed-loop gain, but neither expects a standard consumer line level input to drive it to full power. The presence of a preamp (or line amp) is implied if the source is at standard consumer line level.
So, you might want to consider these amps (one old and one new) as typical with respect to sensitivity. Anything in the 1 to 1.5 volt range would be considered normal. Expressed in dBV, this is about 0 to 3.5 dBV, but the sensitivity spec is usually just expressed as the input RMS signal voltage.
Most power amplifiers, whether tubed or solid state, will have a sensitivity specification in the range of 1 to 1.5 volts RMS for full output. As examples, the Dynaco ST-70 power amplifier had a sensitivity spec of 1.3 volts in for 35 watts out; and the modern NAD C298 solid state power amplifier specifies a sensitivity of 1.43 volts in for 185 watts out. Clearly, these two amps have different closed-loop gain, but neither expects a standard consumer line level input to drive it to full power. The presence of a preamp (or line amp) is implied if the source is at standard consumer line level.
So, you might want to consider these amps (one old and one new) as typical with respect to sensitivity. Anything in the 1 to 1.5 volt range would be considered normal. Expressed in dBV, this is about 0 to 3.5 dBV, but the sensitivity spec is usually just expressed as the input RMS signal voltage.
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Thanks for the reminder of the old days . . .
The old 600 Ohm Audio boards of recording studios, and radio stations used 0.775Vrms, and called that 0dBu.
By the way, in a 600 Ohm professional System 0dBu was 1 milliwatt rms (we are talking of a sine wave here, not special shaped test signals, and not dynamic music).
That was the Professional Standard, having absolutely nothing to do with home Hi Fi and home Stereo.
Since then, the 600 Ohm system has been changed, the end user inputs are often much higher than 600 Ohms, because there are so many parallel users of a single 0dBu signal.
The same methodology of 75 Ohm professional video equipment, used to be only one 75 Ohm user load at a time, but now many Professional systems parallel up 2 or more users from the same 75 Ohm source (that means all but one user has to be high impedance, much higher than 75 Ohms). Many of these use what is called a 'pass through' connection.
When digital video came along, reflections from multiple users became even more important.
7MHz bandwidth Analog video and 256MHz Digital Video have completely different requirements to make it work properly.
In general, 7MHz analog video is 'easy' compared to 256MHz digital video.
Just my old recollection.
Stick to:
Either Hi Fi / Stereo for the home,
Or to Professional Recording and Broadcasting Systems.
They are not the same.
Just my opinion.
The old 600 Ohm Audio boards of recording studios, and radio stations used 0.775Vrms, and called that 0dBu.
By the way, in a 600 Ohm professional System 0dBu was 1 milliwatt rms (we are talking of a sine wave here, not special shaped test signals, and not dynamic music).
That was the Professional Standard, having absolutely nothing to do with home Hi Fi and home Stereo.
Since then, the 600 Ohm system has been changed, the end user inputs are often much higher than 600 Ohms, because there are so many parallel users of a single 0dBu signal.
The same methodology of 75 Ohm professional video equipment, used to be only one 75 Ohm user load at a time, but now many Professional systems parallel up 2 or more users from the same 75 Ohm source (that means all but one user has to be high impedance, much higher than 75 Ohms). Many of these use what is called a 'pass through' connection.
When digital video came along, reflections from multiple users became even more important.
7MHz bandwidth Analog video and 256MHz Digital Video have completely different requirements to make it work properly.
In general, 7MHz analog video is 'easy' compared to 256MHz digital video.
Just my old recollection.
Stick to:
Either Hi Fi / Stereo for the home,
Or to Professional Recording and Broadcasting Systems.
They are not the same.
Just my opinion.