If we follow this thread with atypical unrelenting distracting forum answers, it proves the same point: https://www.stereonet.com/forums/to...er-amp-do-i-want-more-volume/page/2/#comments Note only one forum member asks the right question which is "What is the input sensitivity of your power amp? " The owner had an equivalent input sensitivity to the Quad 306 with a Cambridge amp with 370mv, but sold it, and there the problems started because the amplifier he replaced it with,teased with more power but of course that power was never achieved because (the unstated but consumer found ) sensitivity was higher .
What is pertinent is he has a DAC device rated just over 0dBfs, but of course 0dBFs is never present, only consumer line level. You can work out how much money was wasted in moving away from an amplifier that had the correct input sensitivity
What is pertinent is he has a DAC device rated just over 0dBfs, but of course 0dBFs is never present, only consumer line level. You can work out how much money was wasted in moving away from an amplifier that had the correct input sensitivity
It's better to have an amp with a higher sensitivity and if necessary simply attenuate the output of the dac.
Even this is not needed as his 'passive' preamp also has switchable attenuators.
I suspect the reason for the OPs question boils down to his passive preamp volume control only being useable over the first 25% or so of it's travel due to the combination of the 306's high sensitivity and the dacs higher out.
Even this is not needed as his 'passive' preamp also has switchable attenuators.
I suspect the reason for the OPs question boils down to his passive preamp volume control only being useable over the first 25% or so of it's travel due to the combination of the 306's high sensitivity and the dacs higher out.
Both are correct. The digital stream has a certain level, not in the waveform amplitude but in the digital code. Has to do with amongs others how loud it has been recorded. Same as the level is 'encoded' in the groove amplitudes on an LP record.
But a 1V DAC output setting will definitely sound less loud than a 3V DAC output setting. A factor 3 less loud of course, about 8dB IIRC.
Jan
Thanks Jan.
It's reassuring to know that I'm not just imagining the volume differential between 1V, 2V and 3V output options, from my DAC. 😊
My original question from Post #34...
Whilst I was always aware of several ways in which I can reduce the overall signal in order to make full and best use of our stepped attenuator, I don't think my question is unreasonable.
It is my thinking that other QUAD 306 owners - who don't share my passive preamp and output adjustable DAC - might also find the answer to this question useful.
Whilst I was always aware of several ways in which I can reduce the overall signal in order to make full and best use of our stepped attenuator, I don't think my question is unreasonable.
It is my thinking that other QUAD 306 owners - who don't share my passive preamp and output adjustable DAC - might also find the answer to this question useful.
What is not said, is Only if playing a warned 0DbFS test track to occupy otherwise unused headroom, As 0.894V Peak to Peak or 0.316V RMS is available on a CD, It is why Quad a reputable manufacturer since 1936 provided 0.375V RMS sensitivity with the 306 , because 0.316V RMS is consumer line level, and audio is arguably far more enjoyable, not adding unnecessarily distortion with voltage amplification prior to a power amp.
No, from over 13 years of experience with the 306, and it never overloading playing any CD, all you need do is connect your CD player to your passive attenuator input, and Quad 306 from it's output and press play. Your CD outputs a maximum of 0.316v RMS as does your DAC because the maximum level is embedded in the media, you can press as many selections of your DAC as you like but it still outputs 0.316V RMS maximum ,... it may, as I alluded to earlier arrange slightly different current capability but that's not voltage ... noting though to never play any Test Disc..... , it couldn't be simpler. There is no need to attenuate because you already generally have the correct matching.
The matching can be improved further by having extremely high series resistance at lowest volume , and adjustable shunt resistance to achieve no adverse loading to the source component, but that awaits a change of attenuator.
Oh and be very thankful you chose the 306, (and your passive to make the most of your source component capability ) which demonstrates excellent compliance to known audio levels, which is what is expected from such a trusted manufacturer.
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Chris, if that is the case, then why do we see output levels (far) above 1Vrms these days? Reputable DACs often can be jumper set to 1V, 2V and even 4V output levels. I know where the 0.316V comes from, but that has been left in the dust a long time ago.
The high sensivity of these components can cause awkward volume control ranges. The problem is real with those components.
Jan
Hi Jan
We see this in advertising, but it ends up we lose relationship to actual levels originating with the media, and begin believing that equipment creates levels
when its the media via the equipment that has provided consumer line level. Awkwardly there is a trend for amplifiers not to state their sensitivity and results in consumer confusion, with on one hand apparent large power output, but actually much less output because the equipment sensitivity is never reached, see #61
The 1v 2v and 4V levels are allowing headroom, that is ordinarily never present, and not as far as I know the DAC rearranging consumer line level to jump up in voltage. The only exception is if you happen to need to experience a Test CD providing 0DbFS which comes with adequate precautions, You would certainly select your DAC to the higher level, such as if measuring using a scope, the level 0dbFS can provide.
Why 0.316V RMS is used as the output of the media, is to preserve dynamic headroom for enjoyable music replay with digital source equipment.
This results from digital not being forgiving, and when you run out of headroom hard clipping can occur. We can find reference to that level with the Audio Engineering Society https://www.aes.org/par/l/ and is typically seen expressed as -10dBV and annotated as consumer line level where RCA connections are provided. "-10 dBV Standard voltage reference level for consumer and some pro audio use (e.g. TASCAM), equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units operating at -10 dBV levels.)
We also find it with Streaming services , although not expressed as consumer line level, instead as Loudness Units Full Scale , where there are many selections available but most stick to minus -14 LUFS, noting the end user can have choice too of the level. There is some agreement that -14 LUFS is close if not the same as -10dbV
Loudness Standards for Music Streaming Platforms
Spotify: -14 LUFS (integrated)
Apple Music: -16 LUFS (integrated)
YouTube: -14 LUFS (integrated)
Tidal: -14 LUFS (integrated)
Amazon Music: -14 LUFS (integrated)
Deezer: -15 LUFS (integrated)
Of course had we adopted Murray Crosby's ideas and found as companding by Dolby and DBX we might have instead 2: 1 compression and 1:2 expansion, recordings, where the improvement would be in noise floor , particularly with 16 bit equipment. There would have been less need for preserving dynamic headroom with level , rather we would have all been entertained by what was possible.
We see this in advertising, but it ends up we lose relationship to actual levels originating with the media, and begin believing that equipment creates levels
when its the media via the equipment that has provided consumer line level. Awkwardly there is a trend for amplifiers not to state their sensitivity and results in consumer confusion, with on one hand apparent large power output, but actually much less output because the equipment sensitivity is never reached, see #61
The 1v 2v and 4V levels are allowing headroom, that is ordinarily never present, and not as far as I know the DAC rearranging consumer line level to jump up in voltage. The only exception is if you happen to need to experience a Test CD providing 0DbFS which comes with adequate precautions, You would certainly select your DAC to the higher level, such as if measuring using a scope, the level 0dbFS can provide.
Why 0.316V RMS is used as the output of the media, is to preserve dynamic headroom for enjoyable music replay with digital source equipment.
This results from digital not being forgiving, and when you run out of headroom hard clipping can occur. We can find reference to that level with the Audio Engineering Society https://www.aes.org/par/l/ and is typically seen expressed as -10dBV and annotated as consumer line level where RCA connections are provided. "-10 dBV Standard voltage reference level for consumer and some pro audio use (e.g. TASCAM), equal to 0.316 Vrms. (Tip: RCA connectors are a good indicator of units operating at -10 dBV levels.)
We also find it with Streaming services , although not expressed as consumer line level, instead as Loudness Units Full Scale , where there are many selections available but most stick to minus -14 LUFS, noting the end user can have choice too of the level. There is some agreement that -14 LUFS is close if not the same as -10dbV
Loudness Standards for Music Streaming Platforms
Spotify: -14 LUFS (integrated)
Apple Music: -16 LUFS (integrated)
YouTube: -14 LUFS (integrated)
Tidal: -14 LUFS (integrated)
Amazon Music: -14 LUFS (integrated)
Deezer: -15 LUFS (integrated)
Of course had we adopted Murray Crosby's ideas and found as companding by Dolby and DBX we might have instead 2: 1 compression and 1:2 expansion, recordings, where the improvement would be in noise floor , particularly with 16 bit equipment. There would have been less need for preserving dynamic headroom with level , rather we would have all been entertained by what was possible.
My assumption when designing a multi input source preamp is
Legacy inputs like old tuners, tape decks etc: 200mV
Modern digital sources like DACs and CD players: 1V
So the preamp line stage is set for 14 dB gain, and the modern 1V input sources are attenuated at the input connector by -14 dB. This gives 1V for all sources at the preamp output.
There is a spread in the source voltage figures I quoted above: some modern digital sources quote 1.6 to 2 V output (quite a few CD players over the years) while seen I’ve legacy sources quoted at 120mV (old tuners for example) all the way up to 350mV.
For phono preamps, I design for 35-40 dB for 5 mV input and that feeds into the 14 dB line stage.
With the gain structure mentioned, the volume control will easily cater for a 6 dB spread in input levels without requiring it to be too far off the nominal setting which on a log taper pot will usually be between say 10 o’clock and 2 o’clock on the volume dial. Amplifier rated full output for rated input levels is with the volume control at maximum.
I find it a bit strange that modern digital gear is coming out with 3 and 4 volt output levels.
Ultimately, the volume control on your preamp sets the final preamp output level and no source signal should be clipping at the preamp output level.
On legacy gear like the Quad being discussed here, c. 350mV input sensitivity was the norm, so the aforementioned gain structure would not have the +14 dB line amp - the gain would just be 0 dB.
In this specific case, I would not fiddle with the power amp gain - you could run into stability issues if you try to reduce it by a large amount which is clearly what would be required. I would suggest a circa 10:1 attenuator using a 10k and a 1k divider, the output of which feeds into the volume control. If the volume control is 10 k of better, the loading on the divider will be minimal, but you could always tweak it by reducing the upper 10k divider resistor to say 8.2k or 7.5k.
From what I’ve heard, digital attenuation always reduces resolution - resistive dividers do not.
YMMV
Legacy inputs like old tuners, tape decks etc: 200mV
Modern digital sources like DACs and CD players: 1V
So the preamp line stage is set for 14 dB gain, and the modern 1V input sources are attenuated at the input connector by -14 dB. This gives 1V for all sources at the preamp output.
There is a spread in the source voltage figures I quoted above: some modern digital sources quote 1.6 to 2 V output (quite a few CD players over the years) while seen I’ve legacy sources quoted at 120mV (old tuners for example) all the way up to 350mV.
For phono preamps, I design for 35-40 dB for 5 mV input and that feeds into the 14 dB line stage.
With the gain structure mentioned, the volume control will easily cater for a 6 dB spread in input levels without requiring it to be too far off the nominal setting which on a log taper pot will usually be between say 10 o’clock and 2 o’clock on the volume dial. Amplifier rated full output for rated input levels is with the volume control at maximum.
I find it a bit strange that modern digital gear is coming out with 3 and 4 volt output levels.
Ultimately, the volume control on your preamp sets the final preamp output level and no source signal should be clipping at the preamp output level.
On legacy gear like the Quad being discussed here, c. 350mV input sensitivity was the norm, so the aforementioned gain structure would not have the +14 dB line amp - the gain would just be 0 dB.
In this specific case, I would not fiddle with the power amp gain - you could run into stability issues if you try to reduce it by a large amount which is clearly what would be required. I would suggest a circa 10:1 attenuator using a 10k and a 1k divider, the output of which feeds into the volume control. If the volume control is 10 k of better, the loading on the divider will be minimal, but you could always tweak it by reducing the upper 10k divider resistor to say 8.2k or 7.5k.
From what I’ve heard, digital attenuation always reduces resolution - resistive dividers do not.
YMMV
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You can have 32 bit or more digital attenuators that decrease resolution less than the S/N reduction with resistive attenuators.
I don't think you can make a general statement that one is better than the other, it all depends.
Jan
I don't think you can make a general statement that one is better than the other, it all depends.
Jan
With resistive divider you lose some SNR as the preamp will have the same gain for low input signal as for high.
I use non GNFB current conveyor in my preamps with two set of gain, high and low with the same SNR.
I am not sure I explained it clearly.🙁
Something like this. Gain P1/Rg1 or lower with Rg1 parallel with Rg2.
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Fair enough Jan, on 32 bit stuff I agree but a lot of it out there isn’t that good. The noise floor on a divider feeding a 10 k pot is still very impressive. Best of all, it’s pennies to implement 😊
Are you referring to 1V as peak to peak where the standard provided is 0.894Vpp or as RMS ? https://en.wikipedia.org/wiki/Line_level
The present state of affairs is sadly one of not providing the products input sensitivity in specifications, not showing leadership with what are well known line level standards, and having distortion introduced after source components, prior to the power amp. We see motivation to introduce confusion to the consumer, by stating levels that are unrelated to standards, as only headroom. Disturbingly where stated power levels of output are provided, are then subsequently found substantially less by the purchaser, because input sensitivity ( why it is hidden in data) bears no relationship to established standards. see #61
The Quad 306 remains a beacon of correctness. I would strongly advocate all power amps now comply with sensitivity essentially the same as the AES consumer line level specification. Quad as example provided since 1967 to 1993 sensitivity of 500mv, but bless them improved that further with the 306 to 375mv.The preamp if preferred over a passive can instead be a device not increasing voltage but delivering current, so the source impedance never has adverse loading. Noting #68 where this can also be done more easily with redesign of a passive attenuator.
Abiding by consumer line level standards for all power amplifiers as the Quad 306 does, makes perfect sense. .