Douk G7 Amplifier Review

[beagleman]

Relative to −10 dB, 0 dB corresponds to about 3.16× higher signal amplitude and 10× more power. However, human hearing is logarithmic as well, so this 10 dB increase is typically perceived as roughly twice as loud. So physically it’s ten times the power, about 3.16 times the amplitude, and subjectively about double the loudness.

I know all of this..........

Im not sure if you are arguing, trying to explain something I am very well versed on or being obtuse...??

Its just a meter show the volume level of a signal going THROUGH the unit. Just like a cassette deck on playback, it shows the Level of the music on a tape, well this shows the level of music relative to ITSELF, on a meter.

 

[Cbdb2]

I know all of this..........

Im not sure if you are arguing, trying to explain something I am very well versed on or being obtuse...??

Its just a meter show the volume level of a signal going THROUGH the unit. Just like a cassette deck on playback, it shows the Level of the music on a tape, well this shows the level of music relative to ITSELF, on a meter.

A meter on a tape machine is necessary. It shows the level your putting to tape so you can maximize signal to noise without overloading the tape. This G7 meter is a toy that dosnt tell you much. Dbs are a ratio so what does relative to itself mean (and it auto ranges)? Ild rather have an amp clipping indicator.

 

[Lambda]

What? You do not own or have access to a DB meter?

Sure my router can show the WiFi strength in dB

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.26) or root-power ratio of 101/20 (approximately 1.12).<a href="https://en.wikipedia.org/wiki/Decibel#cite_note-auto-1"><span>[</span>1<span>]</span></a><a href="https://en.wikipedia.org/wiki/Decibel#cite_note-auto1-2"><span>[</span>2<span>]</span></a>

It is Relative to what?
And what kind of signal is actually measured?
How is this meter on the amp in any way related to dB SPL in my room waht are you trying to say?

Lets say i listen to 1khz sine wave a -20dB FS on my DAC and its 80dB(A)SPL in my room. What would the Amp showing in on the VU "meter"
You can't tell because its not related

 

[amirm]

Lets say i listen to 1khz sine wave a -20dB FS on my DAC and its 80dB(A)SPL in my room. What would the Amp showing in on the VU "meter"
You can't tell because its not related

I think he is saying that if you did run that experiment, whatever is then shown on that VU meter is 80 dBSPL. Turn the volume up and down and the relative values will tell you the new dB, assuming the VU meter is accurate that way.

 

[EJ3]

Sure my router can show the WiFi strength in dB

It is Relative to what?
And what kind of signal is actually measured?
How is this meter on the amp in any way related to dB SPL in my room waht are you trying to say?

Lets say i listen to 1khz sine wave a -20dB FS on my DAC and its 80dB(A)SPL in my room. What would the Amp showing in on the VU "meter"
You can't tell because its not related

No, one to measure your room with.
Are you being intentionally obtuse?
Or are you just not well versed in the basics?

 

[Lambda]

Or are you just not well versed in the basics?

You don't seam to understand what dB is.
I can give you a cooking recipe in dB

Ingredients (dB re 1 kg)​

• Flour: −6.0 dB
• Sugar: −8.2 dB
• Butter: −10.0 dB
• Chocolate chips: −7.0 dB

---

Baking Parameters​

• Oven temperature: +2.2 dB
• Baking time: 28.6 dB

---

Instructions​

1. Preheat oven to +2.2 dB
2. Mix all ingredients until uniform
3. Place dough on baking tray
4. Bake for 28.6 dB of time
5. Remove, cool, and consume when signal-to-cookie ratio is optimal

but this is meaningless if you don't define what it is relative to
dB temperature is relative to 0 degree c on a Kelvin scale
dB time is relative to 1 second
dB Wright is relative to 1 Kg

Without defining if is all meaningless dB temperature means nothing if wen don't define a if we talk Celsius, Kelvin, Fahrenheit and what the Reference is.

Turn the volume up and down and the relative values will tell you the new dB,

But it is not because of the auto scale function

 

[amirm]

But it is not because of the auto scale function

Auto scale has an indicator. So maybe you get all masochistic and take that into account as well!

 

[EJ3]

You don't seam to understand what dB is.
I can give you a cooking recipe in dB

Interesting recipe, it looks like it will work well in the field of cooking.
Maybe I can get around to trying it when my wife is away (she does not like Non-Asian cooking & that is fine, I am not good at Asian cooking.
But I am OK at many of the Central/Western European and American styles of cooking (but I do where an apron that has a skull & crossbones on it with the blurb "Death from Within" below them, just in case.

The meters on the Douk G7 Amplifier: which do not state anything about what they are actually reading (although they can apparently read more than 100% of it).
This means that it is up to YOU to obtain a SOUND PRESSURE measuring device (commonly known as a Sound Level Meter, a DECIBLE meter or DB meter) and corelate it with whatever the Douk G7 Amplifier meters read.
As to DB and how it is being used here, it is the sound pressure in your room (and it's relation ship with the unknown readings of the meters on the

Douk G7 Amplifier​

I realize that this could be an arduous task but the rewards will be immense for yourself, should you chose to take on this learning curve.
So I'll give you this information that I obtained from Wikipedia (who, while getting many things wrong, usually gets this type of thing correct) and puts it in a better and more concise way than I can (I hope that this helps clear up your confusion), enjoy and good luck!:

​

Sound Pressure Article​

From Wikipedia, the free encyclopedia (EJ3 says there is a lot more information in this article if you need more. But, this may be 'good 'nuff' for the purpose at hand.
Not to be confused with Sound energy density.

​

Symbols

p, SPL, LPA

v, SVL

δ

I, SIL

P, SWL, LWA

W

w

E, SEL

Z

AF

TL

Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa).[1]​

Mathematical definition​

​

Sound pressure diagram:

​

1. Silence
2. Audible sound
3. Atmospheric pressure
4. Sound pressure

A sound wave in a transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure.
Sound pressure, denoted p, is defined by

where

• ptotal is the total pressure,
• pstat is the static pressure.

Sound measurements​

Sound pressure level (SPL) or acoustic pressure level (APL) is a logarithmic measure of the effective pressure of a sound relative to a reference value.

• p0 is a reference sound pressure,
• 1 Np is the neper,
• 1 B = (⁠
  
  1/2​
  ⁠ ln 10) Np is the bel,
• 1 dB = (⁠
  
  1/20​
  ⁠ ln 10) Np is the decibel.

The commonly used reference sound pressure in air is[7]
p0 = 20 μPa,
which is often considered as the threshold of human hearing (roughly the sound of a mosquito flying 3 m away). The proper notations for sound pressure level using this reference are Lp/(20 μPa) or Lp (re 20 μPa), but the suffix notations dB SPL, dB(SPL), dBSPL, and dBSPL are very common, even if they are not accepted by the SI.[8]
Most sound-level measurements will be made relative to this reference, meaning 1 Pa will equal an SPL of

.
The main instrument for measuring sound levels in the environment is the sound level meter. Most sound level meters provide readings in A, C, and Z-weighted decibels and must meet international standards such as IEC 61672-2013.

​

The lower limit of audibility is defined as SPL of 0 dB, but the upper limit is not as clearly defined. While 1 atm (194 dB peak or 191 dB SPL)[11][12] is the largest pressure variation an undistorted sound wave can have in Earth's atmosphere (i. e., if the thermodynamic properties of the air are disregarded; in reality, the sound waves become progressively non-linear starting over 150 dB), larger sound waves can be present in other atmospheres or other media, such as underwater or through the Earth.[13]

​

Equal-loudness contour, showing sound-pressure-vs-frequency at different perceived loudness levels​

Ears detect changes in sound pressure. Human hearing does not have a flat spectral sensitivity (frequency response) relative to frequency versus amplitude. Humans do not perceive low- and high-frequency sounds as well as they perceive sounds between 3,000 and 4,000 Hz, as shown in the equal-loudness contour. Because the frequency response of human hearing changes with amplitude, three weightings have been established for measuring sound pressure: A, B and C.
In order to distinguish the different sound measures, a suffix is used: A-weighted sound pressure level is written either as dBA or LA, B-weighted sound pressure level is written either as dBB or LB, and C-weighted sound pressure level is written either as dBC or LC. Unweighted sound pressure level is called "linear sound pressure level" and is often written as dBL or just L. Some sound measuring instruments use the letter "Z" as an indication of linear SPL.[13]

Distance​

The distance of the measuring microphone from a sound source is often omitted when SPL measurements are quoted, making the data useless, due to the inherent effect of the inverse proportional law. In the case of ambient environmental measurements of "background" noise, distance need not be quoted, as no single source is present, but when measuring the noise level of a specific piece of equipment, the distance should always be stated. A distance of one metre (1 m) from the source is a frequently used standard distance. Because of the effects of reflected noise within a closed room, the use of an anechoic chamber allows sound to be comparable to measurements made in a free field environment.[13]

 

[SoySalsaPicante]

Interesting recipe, it looks like it will work well in the field of cooking.
Maybe I can get around to trying it when my wife is away (she does not like Non-Asian cooking & that is fine, I am not good at Asian cooking.
But I am OK at many of the Central/Western European and American styles of cooking (but I do where an apron that has a skull & crossbones on it with the blurb "Death from Within" below them, just in case.

The meters on the Douk G7 Amplifier: which do not state anything about what they are actually reading (although they can apparently read more than 100% of it).
This means that it is up to YOU to obtain a SOUND PRESSURE measuring device (commonly known as a Sound Level Meter, a DECIBLE meter or DB meter) and corelate it with whatever the Douk G7 Amplifier meters read.
As to DB and how it is being used here, it is the sound pressure in your room (and it's relation ship with the unknown readings of the meters on the

Douk G7 Amplifier​

I realize that this could be an arduous task but the rewards will be immense for yourself, should you chose to take on this learning curve.
So I'll give you this information that I obtained from Wikipedia (who, while getting many things wrong, usually gets this type of thing correct) and puts it in a better and more concise way than I can (I hope that this helps clear up your confusion), enjoy and good luck!:

​

Sound Pressure Article​

From Wikipedia, the free encyclopedia (EJ3 says there is a lot more information in this article if you need more. But, this may be 'good 'nuff' for the purpose at hand.
Not to be confused with Sound energy density.

​

Symbols

p, SPL, LPA

v, SVL

δ

I, SIL

P, SWL, LWA

W

w

E, SEL

Z

AF

TL

Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average or equilibrium) atmospheric pressure, caused by a sound wave. In air, sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit of sound pressure is the pascal (Pa).[1]​

Mathematical definition​

​

Sound pressure diagram:

​

1. Silence
2. Audible sound
3. Atmospheric pressure
4. Sound pressure

A sound wave in a transmission medium causes a deviation (sound pressure, a dynamic pressure) in the local ambient pressure, a static pressure.
Sound pressure, denoted p, is defined by

where

• ptotal is the total pressure,
• pstat is the static pressure.

Sound measurements​

Sound pressure level (SPL) or acoustic pressure level (APL) is a logarithmic measure of the effective pressure of a sound relative to a reference value.

• p0 is a reference sound pressure,
• 1 Np is the neper,
• 1 B = (⁠
  
  1/2​
  ⁠ ln 10) Np is the bel,
• 1 dB = (⁠
  
  1/20​
  ⁠ ln 10) Np is the decibel.

The commonly used reference sound pressure in air is[7]
p0 = 20 μPa,
which is often considered as the threshold of human hearing (roughly the sound of a mosquito flying 3 m away). The proper notations for sound pressure level using this reference are Lp/(20 μPa) or Lp (re 20 μPa), but the suffix notations dB SPL, dB(SPL), dBSPL, and dBSPL are very common, even if they are not accepted by the SI.[8]
Most sound-level measurements will be made relative to this reference, meaning 1 Pa will equal an SPL of

.
The main instrument for measuring sound levels in the environment is the sound level meter. Most sound level meters provide readings in A, C, and Z-weighted decibels and must meet international standards such as IEC 61672-2013.

​

The lower limit of audibility is defined as SPL of 0 dB, but the upper limit is not as clearly defined. While 1 atm (194 dB peak or 191 dB SPL)[11][12] is the largest pressure variation an undistorted sound wave can have in Earth's atmosphere (i. e., if the thermodynamic properties of the air are disregarded; in reality, the sound waves become progressively non-linear starting over 150 dB), larger sound waves can be present in other atmospheres or other media, such as underwater or through the Earth.[13]

​

Equal-loudness contour, showing sound-pressure-vs-frequency at different perceived loudness levels​

Ears detect changes in sound pressure. Human hearing does not have a flat spectral sensitivity (frequency response) relative to frequency versus amplitude. Humans do not perceive low- and high-frequency sounds as well as they perceive sounds between 3,000 and 4,000 Hz, as shown in the equal-loudness contour. Because the frequency response of human hearing changes with amplitude, three weightings have been established for measuring sound pressure: A, B and C.
In order to distinguish the different sound measures, a suffix is used: A-weighted sound pressure level is written either as dBA or LA, B-weighted sound pressure level is written either as dBB or LB, and C-weighted sound pressure level is written either as dBC or LC. Unweighted sound pressure level is called "linear sound pressure level" and is often written as dBL or just L. Some sound measuring instruments use the letter "Z" as an indication of linear SPL.[13]

Distance​

The distance of the measuring microphone from a sound source is often omitted when SPL measurements are quoted, making the data useless, due to the inherent effect of the inverse proportional law. In the case of ambient environmental measurements of "background" noise, distance need not be quoted, as no single source is present, but when measuring the noise level of a specific piece of equipment, the distance should always be stated. A distance of one metre (1 m) from the source is a frequently used standard distance. Because of the effects of reflected noise within a closed room, the use of an anechoic chamber allows sound to be comparable to measurements made in a free field environment.[13]

You’re going 13 miles on an 11-mile stretch of road over dancey needles on a $300 amp.

 

[EJ3]

You’re going 13 miles on an 11-mile stretch of road over dancey needles on a $300 amp.

You are correct!
I'm not buying it, I'm good with what I have. I suspect that he's not going to buy it either.
Just havin' fun.
But, because the dancey needles are fictitious, if he wants to corelate it with something...
He has a method. It won't be accurate or precise. But better than the meters by themselves.
On my amp that runs my pair of subs, I know the accuracy of my meters:
Colored LED’s on the front panel accurately signal the onset of DPD circuit action and flash at peaks of 3 and 6 dB above rated power. The dimly lit (EJ3: not any more: incandescent has been replaced with LED) meters cannot be read at any distance from the amplifier, and their indications were consistently about 40 percent low. They responded to burst signals so rapidly, however, that with our 20-millisecond test signal they read only 3 dB lower than the amp’s steady-state value. (at 8 ohms).
I typically run at 4 ohms (dual mono) for my subs.
As to how much power can I put into my subs (the raw speaker are automotive competition speakers and can handle more than I can give to them), here is an amp dyno test (not of my personal one but of the same make and model [except that mine is a bridgeable model]):

As to why meters mostly disappeared: m. Zillch (at AVS forums) had this to say:
VU meters are awesome! They aren't super accurate but that doesn't matter because they still convey a great, rough explanation to a layperson of roughly what's going on, at least relatively. I'm convinced they disappeared from consumer gear because, despite being fairly inexpensive to include for the manufacturers, they realized they didn't provide data which helped sales but instead hurt (future) sales. Keeping consumers in the dark and suffering from "watt fever" is to their advantage.

Many people got them (power level meters) and quickly realized:

"Hey, I actually only consume under 10 watts most of the time for nearly every typical use I have, and on those rare occasions when I want to blast it I can see that I definitely would not be satisfied with an amp that's only double the watts/ch (+3dB higher output), heck, even quadruple the power (+6dB) of my current unit, for that matter: I'd want one that's more like, at the very least, 10X the power, i.e. plays 10dB higher (example: owning a 40 w/ch amp and wishing you had 400 w/ch) but I'm stuck because my speakers aren't even rated to take that much!"

 

[Lambda]

You’re going 13 miles on an 11-mile stretch of road over dancey needles on a $300 amp.

And nothing more it is. Its just the Ascetic cargo cult of a meter.

@EJ3 ​

"Measuring" with this amp about a good of measurement as measuring Lumens of a light source in a YouTube video with a color picker.

As long a you don't know the ISO,Shutter speed, aperture, Gama curve, etc. you can tell nothing about the actually brightness and especially not about Lumens

 

[EJ3]

And nothing more it is. Its just the Ascetic cargo cult of a meter.

I find them useful for manually setting the relative (yes, I know, a "squishy" term) volume levels on my Tri-Amped System.
An amp for the left speaker, for the right speaker and an dual mono amp for the pair of DIY subs.
YMMV.

 

[Lambda]

Imagine dB as just a fancy logarithmic way of saying percentage.
You can express many things as a percentage: temperature, weight, volume, speed, time, etc.
But in order to make sense of 50%, you need to define two things: what you are measuring, and what 100% correlates to.

“I drive at 90%” has no meaning, but “I drive at 90% of the legal speed limit of 120 kilometers per hour” does.
It defines 120 km/h as 100% and defines a measurement of speed.

These two things always need to be defined when talking about % or dB.

If we talk about km/h, it is implicitly clear that we are talking about speed, in the same way it is implicitly clear that if we talk about dB SPL, we usually assume 20 µPascal as 0 dB.

But the amp displays the level of an electrical signal with no fixed relationship to pressure.

For electrical signals, therefore, we need to define these two things again.
Are we looking at power, voltage, or current?
And what is 100% voltage or power?

Therefore, we say things like dBu, dBV, dBm, and so on.

I find them useful for manually setting the relative (yes, I know, a "squishy" term) volume levels on my Tri-Amped System.

And this is the catch. You can’t do this because of the auto gain.

Let’s drop the fancy units and measurements and say you want to set all amps to “50% volume” or “50% loudness” or “50% power.” Whatever.
The reasoning is, they all display the same thing, and that thing is correlated to how loud it is so they are alt at the same volume no matter waht the thing actually is

If it displays the same number, it should be the same no matter waht the number on the display is

Or thermometers: no matter if they are in Fahrenheit, Celsius, or Kelvin, if they show the same number, it’s the same. "hot" or "cold"

But with these amps, this is not the case because of auto gain.
The scale is not the same but constantly adapting.

This is like taking a picture with your phone in automatic mode.
You can’t tell if a shot was lit by a 50 W light bulb or by the sun just from looking at the pixel values.

 

[EJ3]

Imagine dB as just a fancy logarithmic way of saying percentage.
You can express many things as a percentage: temperature, weight, volume, speed, time, etc.
But in order to make sense of 50%, you need to define two things: what you are measuring, and what 100% correlates to.

“I drive at 90%” has no meaning, but “I drive at 90% of the legal speed limit of 120 kilometers per hour” does.
It defines 120 km/h as 100% and defines a measurement of speed.

These two things always need to be defined when talking about % or dB.

If we talk about km/h, it is implicitly clear that we are talking about speed, in the same way it is implicitly clear that if we talk about dB SPL, we usually assume 20 µPascal as 0 dB.

But the amp displays the level of an electrical signal with no fixed relationship to pressure.

For electrical signals, therefore, we need to define these two things again.
Are we looking at power, voltage, or current?
And what is 100% voltage or power?

Therefore, we say things like dBu, dBV, dBm, and so on.




And this is the catch. You can’t do this because of the auto gain.

Let’s drop the fancy units and measurements and say you want to set all amps to “50% volume” or “50% loudness” or “50% power.” Whatever.
The reasoning is, they all display the same thing, and that thing is correlated to how loud it is so they are alt at the same volume no matter waht the thing actually is

If it displays the same number, it should be the same no matter waht the number on the display is

Or thermometers: no matter if they are in Fahrenheit, Celsius, or Kelvin, if they show the same number, it’s the same. "hot" or "cold"

But with these amps, this is not the case because of auto gain.
The scale is not the same but constantly adapting.

This is like taking a picture with your phone in automatic mode.
You can’t tell if a shot was lit by a 50 W light bulb or by the sun just from looking at the pixel values.

I got all my film (home movies) from 1931 (grandparents snow skiing wedding in the Austrian Alps on 9.5mm film) through now digitized.
If I can muddle my way through that, you can get to where you are going with gear, too
I'm sorry that you seem to have a problem for every suggestion.
I have no solutions for you, I guess.
I'm set, happy with what I am doing with my gear and the direction that I'm taking it in.
Good luck with your issues and solutions.

 

[SoySalsaPicante]

 

[EJ3]

View attachment 513197

VERY GOOD TO KNOW WHAT THE METERS ACTUALLY ARE! BRAVO!
AS PEOPLE HAVE BEEN CONFUSING (and maybe CONFLATING) what the meters really are since the thread began.