If you take a typical LP playback system, and look at its signal voltages, its apparent signal levels should come out very close to the CD standard described in the last post.
1. Phono cartridge has specified output of 3mV rms at 1kHz, 5cm/s.
2. Phono preamp has gain of +34dB at 1kHz. (That's 50x gain.)
3. 0.003V * 50 = 0.15V rms, or 150mV rms, 210mV peak.
4. LPs have peak signal levels of about 10dB above that (20x). Therefore, 0.21V peak * 20 = over 4V peak, or about 3V rms! That's in the same ballpark as the CD standard of max signal out = 2.828V peak.
In practice, I've found that I prefer my phono preamp to have about 40dB gain, which makes the subjective level coming from LPs sound about the same as the level coming from my digital sources. If I use a phono preamp with 35dB gain, I notice the level from LPs is noticeably quieter than the level from the DAC playing PCM files.
I looked up the input sensitivity specs for the JBL LSR305 active speaker. It says
Maximum Peak Input Level (-10dBV 'consumer level' setting) = +6dBV
According to https://www.extron.com/calculators/db-to-volts/?tab=tools that means the maximum signal voltage is 1.995V (peak? rms?).
In other words, the sensitivity of the amplifier in that powered speaker is 1.995V (when set to 'consumer level').
I use a pair of those speakers with a Topping D50 DAC and an Intact Audio passive attenuator (no preamp with gain in the system). The output from the DAC drives the powered speakers' inputs directly, with no preamp in the system. There is enough gain for me to clip the amplifiers if I turn the volume up all the way. I'm fine with turning the volume up to 11 or 12 o'clock for my normal listening.
1. Phono cartridge has specified output of 3mV rms at 1kHz, 5cm/s.
2. Phono preamp has gain of +34dB at 1kHz. (That's 50x gain.)
3. 0.003V * 50 = 0.15V rms, or 150mV rms, 210mV peak.
4. LPs have peak signal levels of about 10dB above that (20x). Therefore, 0.21V peak * 20 = over 4V peak, or about 3V rms! That's in the same ballpark as the CD standard of max signal out = 2.828V peak.
In practice, I've found that I prefer my phono preamp to have about 40dB gain, which makes the subjective level coming from LPs sound about the same as the level coming from my digital sources. If I use a phono preamp with 35dB gain, I notice the level from LPs is noticeably quieter than the level from the DAC playing PCM files.
I looked up the input sensitivity specs for the JBL LSR305 active speaker. It says
Maximum Peak Input Level (-10dBV 'consumer level' setting) = +6dBV
According to https://www.extron.com/calculators/db-to-volts/?tab=tools that means the maximum signal voltage is 1.995V (peak? rms?).
In other words, the sensitivity of the amplifier in that powered speaker is 1.995V (when set to 'consumer level').
I use a pair of those speakers with a Topping D50 DAC and an Intact Audio passive attenuator (no preamp with gain in the system). The output from the DAC drives the powered speakers' inputs directly, with no preamp in the system. There is enough gain for me to clip the amplifiers if I turn the volume up all the way. I'm fine with turning the volume up to 11 or 12 o'clock for my normal listening.
Each player reliably every time you insert a CD, plays content on the CD itself that complies with consumer line level which restricts output to 0.31V RMS , You are not the only person misunderstanding that the level is within the media being played, and not the players capability. It's the same for streaming services too where a different standard called Loudness units full scale (LUFS ) is used. most streaming services similarly limit the media being played to -14 LUFS LUFS and RMS are quite different in the way they originate level to be measured, but remarkably are very similar in terms of general tabulation. Most Streaming services media at - 14 LUFS is therefore lower than CD media in level.
Amplifier sensitivity is presently measured in volts RMS, enabling a marvelous opportunity to align the output of media being played to amplifier sensitivity.in so doing having opportunity of little or no loss when used with passive attenuation
Amplifier sensitivity is presently measured in volts RMS, enabling a marvelous opportunity to align the output of media being played to amplifier sensitivity.in so doing having opportunity of little or no loss when used with passive attenuation
I believe there is no confusion.
Those who like to put just signal selector and volume pot before the amp, and call it passive preamp, are free to do so.
Those who like to experiment with tube buffers, jfet buffers, bjt preamps, jfet preamps, tube preamps, and all sorts of hybrid circuits including korg nutube and so on...are free to do so.
I have said it before, and will say it again, passive preamp must feed high impedance input of the first stage of an amplifier, being it jfet or tube, in order to sound good. Passive circuit must not drive low impedance, otherwise it will sound flat and boring.
Active preamp will always be needed if you use F4 or any other buffer to drive speakers. I am experimenting with stepup transformer (like the one used in M2 or VFET) followed by tube buffer. There will be swith to zero gain, 3x and 6x voltage gain, so it can be used for all sorts of amps from Wolverine to F4.
Cheers!
Those who like to put just signal selector and volume pot before the amp, and call it passive preamp, are free to do so.
Those who like to experiment with tube buffers, jfet buffers, bjt preamps, jfet preamps, tube preamps, and all sorts of hybrid circuits including korg nutube and so on...are free to do so.
I have said it before, and will say it again, passive preamp must feed high impedance input of the first stage of an amplifier, being it jfet or tube, in order to sound good. Passive circuit must not drive low impedance, otherwise it will sound flat and boring.
Active preamp will always be needed if you use F4 or any other buffer to drive speakers. I am experimenting with stepup transformer (like the one used in M2 or VFET) followed by tube buffer. There will be swith to zero gain, 3x and 6x voltage gain, so it can be used for all sorts of amps from Wolverine to F4.
Cheers!
You can also have freedom to avoid voltage gain between source and power amp , have no additional buffer and enjoy consumer line level media replay, with ability to have no adverse loading on the source impedance, and make the latter adjustable, as well if you wish, just in case that was not included.
Very interesting for me, it kind of explains a lot but I'm still not sure about what a Consumer Line level of 0.316V rms actually means. Is it the maximum level or some kind of
average ?
hi Zeta4
RMS is a average level ,https://en.wikipedia.org/wiki/Root_mean_square , https://en.wikipedia.org/wiki/Line_level Most sensitivity specifications of power amps are expressed in the same way, so is nicely tangible. As example input sensitivity / consumer line level can tell you how close or far away you are from efficiency .
RMS is a average level ,https://en.wikipedia.org/wiki/Root_mean_square , https://en.wikipedia.org/wiki/Line_level Most sensitivity specifications of power amps are expressed in the same way, so is nicely tangible. As example input sensitivity / consumer line level can tell you how close or far away you are from efficiency .
Thanks Chris. However the Wiki on Line Level suggests that CD levels are an exception being 2V rms "to avoid the need for a preamp" it said. That's what was confusing me as
I'm seeing much higher levels that 0.316V rms from my CD players. This is important for me as I'm designing output transformers for a Dac and peak o/p levels matter.
Sorry if Ive still got it wrong somehow.
I'm seeing much higher levels that 0.316V rms from my CD players. This is important for me as I'm designing output transformers for a Dac and peak o/p levels matter.
Sorry if Ive still got it wrong somehow.
Commercial CD's you play at home always confine the level to 0,31VRMS The level is in the media being played, not the Players capability ,The exception is a Test CD that will warn when 0dbFS is approached. Peak levels in the article are stated as Voltage Peak, and Voltage Peak to Peak, different to average level RMS , see:
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The difficulty I'm having is that I'm seeing peak voltages of over 1V on some CD's so the rms value will be well over 0.316V . I checked the 0dbfs level at 2Vrms using a test disk.
I dont want to hijack this thread so I will recheck for specific track's and levels to be sure of my findings before responding again. Anyway thanks for this I didnt know about
the Consumer Line level.
I dont want to hijack this thread so I will recheck for specific track's and levels to be sure of my findings before responding again. Anyway thanks for this I didnt know about
the Consumer Line level.
Check your output is from your CD player, rather than your DAC, as the latter may or may not then be representative of consumer line level, Possibly additional gain is being selected as part of its available features. RMS in the attached image is light blue, and peak is dark blue.
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an interesting design for passive preamp (mainly for active loudspeakers resp studio monitors - but also for power amps): Level Pilot X
https://www.tcelectronic.com/product.html?modelCode=P0C32
https://de.ifixit.com/Anleitung/How+to+fix+TC+Electronic+Level+Pilot+static+noise/28905
P.S.: I would like to make some updates in post #26 (overview). Maybe one of the moderator can replace post #26 by post #1 - then I can do this.
https://www.tcelectronic.com/product.html?modelCode=P0C32
P.S.: I would like to make some updates in post #26 (overview). Maybe one of the moderator can replace post #26 by post #1 - then I can do this.
Nope, just post what you want to say now. We aren't going to edit people's posts without very good reason.
Passive preamp? There isn't any such thing. It's a pot and maybe a switch. A losser element only that cannot hope to drive cable capacitance or variable input impedance of some amps.
Why can't people understand the most simple concept? Just call it a "pot on a string", because that is really all it is.
Passive preamp? There isn't any such thing. It's a pot and maybe a switch. A losser element only that cannot hope to drive cable capacitance or variable input impedance of some amps.
Why can't people understand the most simple concept? Just call it a "pot on a string", because that is really all it is.
Excellent summary, but here is another one: The Intact Audio series of Autoformers. I use the Blore-Edwards switch equipped on and it is very good.
https://intactaudio.com/atten.html
There are also the Sowter TVCs, also excellent, but I think the Autoformer Volume Control from Intact is more transparent.
https://www.sowter.co.uk/transformer-attenuators.php
Both of the options present a appropriate load to most situations and actually reduce the source impedance as volume is lowered.
My 2 cents, YMMV
They do not add power. The frequency response isn't as wide, and therefore transient response isn't as good as a good preamp.
Here's a stock Nakamichi CA-5 for example ...
This is real measured performance without special care taken. Hint: It's better than most sources. If I look, I could probably find something better. The real kicker is that this is a mass market, commercial product. Not a one-off, hand tuned thing. Very affordable.
I have to ask. Why wouldn't you buy one of these used instead of buying a more expensive transformer based thing? You get RIAA MM and MC inputs as well. On top of that, performance is much better. It also drives real world amplifiers and cables.
Here's a stock Nakamichi CA-5 for example ...
This is real measured performance without special care taken. Hint: It's better than most sources. If I look, I could probably find something better. The real kicker is that this is a mass market, commercial product. Not a one-off, hand tuned thing. Very affordable.
I have to ask. Why wouldn't you buy one of these used instead of buying a more expensive transformer based thing? You get RIAA MM and MC inputs as well. On top of that, performance is much better. It also drives real world amplifiers and cables.
