Dual Pro optimal power output?

[bernardl]

Team,

I have noticed that my new 1000 pro plays louder than the D250 pro at -40.

This led me to wonder whether someone had assessed the impact of max power setting on sound quality?

Would it make sense to set it lower than 1000? Or more generally speaking not to use the dual pro at max rated power?

Thank you.

Cheers,
Bernard

[David A]

I can't comment on whether it's better to set the maximum power setting lower. My guess is probably not but that's just a guess.

Should you avoid using a dual pro at max rated power? What do you mean by "use at max rated power"? The way the DAC and the volume control work in a Devialet is that at a volume setting of 0 dB the amp will deliver its rated power for a digital input of 0 dB. How loud that is going to be in your setup is going to depend on the sensitivity of your speakers, your listening distance, and the degree of support your room provides. With speakers of 90 dB sensitivity, that's going to mean that when a peak of 0 dB comes along, you're going to have a level at your listening position of 110 dB or more, probably a bit more. Based on Australian hearing protection standards, the maximum "safe" exposure to a level of 110 dB is around about 2 minutes a day on a "set and forget" basis.. You're into levels where there's a serious risk of giving yourself noise related hearing loss if by using the amp at maximum power you mean setting the volume level to 0 dB and leaving it there. The first symptoms of that damage are actually difficulty in understanding human speech because the damage occurs first in the mid-range frequencies where the ears are most sensitive so your music listening may be less affected than your ability to simply chat with friends over a meal but the damage spreads out to the highs and lows from there. I somehow think that there's not much sense in buying a D1000 Pro if you're going to use it to wreck your hearing so I definitely recommend that you not use the amp at maximum power unless you're playing something which has been mastered with a lot of headroom, ie the peak volume on the recording is well below 0 dB in level. Such recordings do exist.

Now to your comment that the 1000 Pro plays louder than the 250 at -40 dB. Of course it will. With a Devialet a volume level of -40 dB means a level 40 dB below rated output. With the 250 that's 40 dB below 250 watts/ch and with a 1000 it's 40 dB below 1000w/ch so if you're comparing both amps at the same setting, -40 dB on each amp, then -40 dB on the 1000 is gong to be 6 dB louder than -40 dB on the 250 because each doubling of rated power increases the peak volume level you will hear by 3 dB and rated power doubles twice as you go from 250 W to 1000 W.. If you're comparing 2 Devialets of different power and you're trying to match volume levels by matching the settings, the amp with the higher output is always going to sound louder. In order to match volume levels for the comparison you're going to have to play a test signal, something like a 1 kHz sine wave or a white or pink noise source, even the brown noise source the Devialet has for speaker break in purposes,, measure the sound pressure level at your listening position with an SPL meter, and adjust the volume settings on one or both amps so that each is delivering the same SPL at your listening position. Try that with a 250 and a 1000 and the volume setting on the 1000 is going to be close to 6 dB lower than that on the 250 because of their difference in maximum output. It probably won't be exactly 6 dB lower but it will probably be within +/- 1 dB of that.

I wouldn't reduce the 1000's maximum power rating in the Configurator, I'd leave it at 1000 W. If you want to limit the volume you can play things at, then Roon has an option in the Device Setup options for setting maximum and safe volume setting levels which restrict the operation of the volume control in Roon if you're controlling volume via the Roon remote display.

[bernardl]

Hi David,

Thanks a lot.

I wasn't accurate in my description, I didn't mean maximum output power, I meant maximum power rating in the configurator.

I am well aware about the dangers of loud listening and have never playing my D250 Pro louder than -20db as far as I can recall.

Your explanation makes sense, thank you. I had not realized that -40db was referring to the 0 db of this particular amp, I somehow thought it was referring to an absolute level of sound for some reference speaker load. But yes, now that you mention it it makes total sense.

A ball park figure is good enough for me, so I'll change the default level of the amp to -46db from the default -40db. I believe that this will be much closer to a good start point for general listening.

I have already the limits set up in Roon btw.

Cheers,
Bernard

[David A]

@bernardl ,

Why have the default level at -40 dB or -46 dB? That's extremely low. I've got a 130 so if I followed your reasoning I'd set my default to -37 dB since a 250 has roughly twice the output of the 130, In practice, however, with my speakers in my room, most of my listening is done at around -20 dB, give or take a few dB so I have my default set to -20 dB. I really dislike the -40 dB default because it means I have to raise the volume around 20 dB or so every time I turn the amp on and that's annoying.

Take a look at what level you do most of your listening at and set the default somewhere closer to that unless you're listening too much during a coronavirus lockdown, you're getting a lot less exercise as a result, and expending a bit of energy raising the volume setting every time you turn the amp on makes a difference to your weight :-)

That's my view and I'm sticking to it. I view default settings as convenience settings intended to marke life easier.

[bernardl]

David,

Sure, I understand.

The thing is that -40db was fine for me as default listening level with the D250 Pro and I find -40db too loud with the D1000 Pro. My question was about trying to reproduce the same experience with the dual mono and your answer has been helpful.

My system is in our living room and there is usually somebody with me when I start to listen.

Our speakers may behave very differently, my room absorbs less or I have super sensitive ears, I don't know. The thing is that for my wife and daughter even -46db with the 1000 Pro is considered too loud.

Thanks again for your help!

Cheers,
Bernard

[David A]

Bernard,

I think our rooms probably do make a difference. My system is in a 30 sq. m.room used only for the audio system. It has 2 large archway entrances, one from a hall and another from an open plan area for the living, dining, and kitchen space which together with the hallway area totals about 56 sq. m. and that's also open to another hallway and bedrooms so there's over 60 sq. m. of adjoining space which reduces the listening volume in the room. The room is carpeted and has several acoustic panels and bass traps providing additional absorption to that provided by the carpet and soft furnishings. I'm losing quite a lot of sound pressure from my room through the 2 archways.

If I remember correctly you're in Japan so I suspect your room is smaller than mine (house sizes in Australia are amongst the largest in the world and that goes with bigger rooms). You probably have smaller onnected spaces as well which also makes a difference. I just did a quick mental calculation. In the same room with the same speakers, you would probably be setting the volume level of the 1000 Pro at a level 9 dB below the level you would set on my 140 if you wanted to match actual listening levels so -40 on the 1000 is probably close to -31 dB on my 140 if everything else is equal. If my room is bigger then you would need to set the level on the 140 higher again to compensate for the increase in room size and higher again to compensate for my losses to adjoining spaces which are also probably larger than in your situation. Then I need to increase volume level again to compensate for additional absorption in my case from the acoustic panels in my room and soft furnishings in my adjoined area. All of that is going to be pushing the volume setting I would need to use to match -40 dB with the 1000 in your romp to probably somewhere between -25 dB and -20 dB or even a little more in my situation but then I get a 2 dB gain from the slightly higher sensitivity of my speakers so we can reduce my level slightly for the difference in speaker sensitivity.

All of which means l made the common mistake in my earlier comment about default settings of assuming that all things are equal apart from amp power. All things aren't equal. When it comes to actual sound pressure level at the listening level there may very well be not all that much difference in the levels we both listen at. I may well have to listen at a volume setting of around -25 dB or louder to match the level you get at -40 dB with the 1000 in your room with your speakers.

David

[ogs]

At some point (several years ago - in D-Premier time) Marja&Henk of 6moons discovered that the amp sounded better on their highly efficient horn speakers when power in configurator was set at a low level. I tried this and found that that my D-Premier did sound better (smoother, more resolved) at reduced power. The setting changed (reduced) the voltage to the power stage and also the gain of the amp. I used this for some years. In newer versions of the amp I could not detect any improvement when lowering the power so I kept it at full level. I usually played at -15dB (which is actually -25dB. My room correction convolution took away around 10dB).
If you regularly play at -40dB you may try to reduce power so that you end up at around -10-15dB for the same SPL. The volume control is digital after all and too much attenuation in the digital domain reduces resolution. On the other hand, gobs of power will give you almost limitless dynamics so keep this in mind when experimenting.

[Elztalbiker]

The jump from 250 to 1000 / 250 watts to 1000 Watts = about +3 db more volume. I recommend max -45 db at start volume. It’s not the +3 db alone. You get more bass power and a lot more of dynamics with the result of louder audio level for your ears.




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[David A]

A doubling of amplifier power results in an increase of 3 dB in volume so a jump from 250 to 500 W gives a 3 dB increase and a jump from 250 to 1000 W gives a 6 dB increase because power doubles again from 500 to 1000 W.

There's lots of references to this available on line.

I wouldn't say that you "get more bass power". It may certainly sound like that but what's going on is a result of the sensitivity of our ears at different frequencies and sound pressure levels. The ear becomes increasingly less sensitive as frequency drops so for 2 sounds, one in the bass frequencies and one in the mid range, the sound in the bass frequencies will be perceived by us as less loud than the mid range sound. Increasing the sound pressure level produces a perception of a larger increase in volume in the bass than it does in the mid range because the sensitivity of our ears in the bass range increases a bit as sound pressure level increases we perceive the level of bass increasing more than the level of the mids when both get the same increase in sound pressure level.. Both the bass and the mids get the same increase in power as you increase volume, and it takes the same increase in power in both ranges to get the same increase in sound pressure level but we perceive a greater increase in the loudness of the bass frequencies for that increase than we do for the mid range frequencies. That also contributes to the greater sense of dynamics at higher sound pressure levels that we perceive.

[bernardl]

Hi David, Ops and Elztabiker,

Thanks a lot for your inputs!

The room I am in has a relatively large volume for Tokyo since the ceiling is very high and the room a bit longuish, but is quite narrow, so I am sitting around 3m from the speakers although the room is around 28sqm. The speakers are also fairly close to the back wall which may impact too. so yes, odds are that the actual pressure level isn't that different. I also tend to listen to higher sound levels when I am in a listening mode on my own, typically -35 or -30 on the D1000 Pro for jazz or classical music.

I'll probably try some lower power settings to see if it changes anything for the better.

Thanks again.

Cheers,
Bernard