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Decibel production versus Watts of the amplifier

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I want to ask following question. I am NO expert. Let this be clear, so don't shoot please.

I have a whole collection of Audio. And in that, about 30 amplifiers.

But I am going to pick 3 as to compare them in decibel production versus the Ampliers specs.

1. The Cyrus 7.  Rated at 40 Watt per channel at 8 ohm.

2. A Chinese Classic Yyshung 08 power amp with a preamp. 125 Watt in 8 ohm, 240 in 4 ohm.

3. And my worry Amp. The Thule IA150B.  125 Watt in 8 ohm, 250 in 4 ohm.


last one got overheated, replaced him. Let him cool off. Morning after he was "fine".


Fine, well to me not 100%. Even before the heating problem. 

The volume knob goes to 80 de in steps of 1 db.

I need 40 on the display to have a moderate decibel production. That is 12 o clock.


number 2 only needs the volume at about 7 o clock or less for the same decibel production.


Number 1, the Cyrus with 40 watts needs ALSO about 8 o clock. At 12 o clock you have to begin start running away. Awesome.


The Thule has 16 Transistors to attain the 125 Watts.

still he lacks in DBs .  Clearly . Radio is louder than a cd or internet.

but that is not the issue.


Do I have a problem with my gorgeous Thule, having only 2 inputs. But Creek doesn't do better.

Do I need him being serviced.

40 DBs for a 125 Watt amp and , regardless of the speakers, the DBS do not 🔥 fire.

It is disappointing in a way, Other Thule owners reported other problems .

did some of the 16 transistors die ???


Cyrus are beasts. Like NAD. With 25 watt they blow you away. English of course.


So. If anyone can give some advise or comment please do.

In fact, I have the same issue with the Rega Elicit. Software sensored volume knob.

He also needs 11 o clock for some good sound. Being not the cheapest Amp.


Marantzes, Denons, Sansuis all score much higher than the Thule.


I know volume not only depends of the Number of Watts but you expect a more than decent performer giving the performance per channel.


















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Broadly the "loudness" of an amplifier does not depend upon its maximum rated power output but by its gain i.e the increase in voltage in compared to voltage out.  Most amplifiers, irrespective of maximum power output, have broadly similar gain.  Of course if you keep turning up the volume ultimately the lower powered one will give up first. 


The reason that your amps seem to exhibit different loudness factors is because although some may have  lower or greater gain it is more likely, that their  volume pots do not follow the same law of attenuation.


If your speakers require , say, a 5 volt input to produce a sound level of 70dB it doesn't  matter if the 5 volts comes from a 50 watt or 500 watt amplifier, the 5 volts will still deliver a sound level of 70dB.

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Thanks for responding.

That is what I intend to do.

The amp just had another 3-set on top, I got about 23 systems, cannot put them all in the floor he. But this one , apart from the other,

apparently was not keen on this jail place and suddenly began to distort sound , lower the volume level, and even when cut off, the speakers still gave hard knocks... I said "Ho, this is not right".... few trials afterwards gave the same result.

I displaced him where he stood on top and let hum cool off for the night.

following morning, he was fine... I mean, no drop outs. 

But the 150 Watt engine didn't give much. A NAD 25 wpc sounded 100 times louder. OK sound is not WPC alone, but still, you don't expect a 150 wpc at 8 ohm to perform so poorly.

I let him on standby as they, on the net, a few because Thule is not hot of course on the net, advised to do.

Cause as they said, out of stand by he shoud reach his peak after half an hour, in stead of 4 hours from a cold start.

But last night, my wife shouted me out of bed cause she heard the connected speakers make again those very loud knocks.

From a Thule in stand by.

That is clear... right to the audioexpert. As she went to pick him up, as I got a chronic disablement, they , the sellers, demoed the amplifier. But she recalls the sound was already quite low. 

So, I think it was already a problem at the time of buying. I mean, volume on 1, nothing, 2,3, as of 5 you begin to hear something.

5 out of 80. Not normal.


So, this one must be reviewed.


My Rega elicit has been in for repair too. At Rega in London they even did not see the heating component being too high.

And he also, sensored volume, must raise to 6-7 out of 20 for a reasonable sound level.

Wile those powe amps blow you away at 2-3-4...


Gain, is this something that is controlled inside and what is it really. My Audiolab preamp has a Gain knob. I do not understand what it really does.














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Read this :




Thule (as in Danish amplifiers) seem to have gone out of business at least 10 years ago. It also seems that failure of their amplifiers due to heat damage was not uncommon. Although ( 10 years ago) some spares seem to have been available from other vendors who had bought Thule's stock of parts there seems not to have been any arrangement for continuing service.


I do not know the value of the piece to judge whether or not it may be economically viable to try to get it repaired by an independent service technician but I suspect that as it appears to have had a unique circuit and one that may have required custom parts ( see the remark about the difficulty in fitting replacement leaded electrolytics) it may not be appropriate. However a schematic of the circuit does appear to be available online:




A gain control would be something that changes the ratio between  the incoming and outgoing voltage of a preamp or the preamp section of an integrated amp and is unusual.  Presumably it would improve the ability to electrically match the component being amplified/attenuated via the preamp section with the input sensitivity of the power amplifier section so that overload could not occur.  This was a problem in the early days of CD when many amplifiers had not been designed for the possibility of a 2V input signal.  However some manufacturers have been known to use the term simply as an English  synonym for "volume". As current Audiolab models have only a volume control I assume that you own an earlier model but as I don't know which one I cannot comment further.





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As to the Gain control on the Audiolab the device is a recent preamplifier , the 8200Q.

This one has gain control. It activated in fact a poweramp that wouldn't take off.

I increased the gain and he was off. Don't know why ?



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Having looked at the specification of the 8200Q It works approximately as I indicated earlier by altering the gain  in 3dB increments which is similar to changing the input sensitivity.


I am rather unsure what you mean by increasing the gain so the power amplifier turned off. Do I understand you correctly? I apologise if not. I can only imagine that you increased the gain to such an extent that the power amp it was driving was overloaded and that some form of protection device operated and turned the amplifier off. What was the amplifier that the 8200Q was driving?

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It was an older poweramp from Audiolab, the 480 I think. I got lots of audio so pardon for not being exact. 

I wanted a power amp for the preamp, so I found this rather big power engine that works without preamp to, as he has 2 volume knobs and rca entry for cd or...


With the preamp he only started at gain 7 or 9. 


This is one has power enough.


the Thules SNT, signal to ratio is 112db if that says something.


But my Rega Elicit R also "suffers" from low "loudness". 

His software sensored volume knob has 14 points, 14 leds. 

I need 6 to 7 positions for a decent volume.

this 2000€ amp is not a small one, also integrated but disappoints me in volume.

I got chronically ill 12 years ago and really was not an audiophile, not even now, just a melomane who loved his analogue :):) piano. Nothing more.

Things changed dramatically and now I have an audio store everyone stands completely stunned by the amount of all kind of devices. 

But I have no background.

i even put a question on quora, "Can I study electronics in order to understand architectural designs, but not to solder devices ?" . I would like to know more about this.

SNT is a logarithmic formula. My interest in mathematics can help.

but which books to begin with.

If you can help, very appreciated. Bit like that Paul from PS Audio with all his videos on YouTube. 

I love to know in detail about DSD, MQA...

It is the only thing I still can. Although sitting long is a problem, I must find a solution to be able to read and study. Not easy as it does not get better, on the contrary. 


So Rega disappoints me a little in that volume department to. Volume set halfway for a fair "loud" enough sound.


But my Atoll, Creek, Myryad, Classic (Chinese powerhouse), even Marantz, Teac achieve these volumes under a quarter , so at 8 o clock. Atoll the PA100, astounded me always, as he was one of my first upper end sets. At 2 from 12 is far enough.

Also separately preamplified. But the integrated Myryad does the same.

all with less Watts. Under 100.


And an expensive Rega must be set like a low budget amp. 

Do you understand ? He was also in for repair, and for overheating. The Rega guys didn't tested the heating, so he was transported twice. The overheating was handled here locally, how ? Do not remember. But they knew where the problem sat and did not do anything to prevent. ??? 

I am not a Rega fan anymore. Their DAC power entry was so cheap it broke off.


I am waiting for my technician. I did notice inside, that there are those cylindrical towers marked 10000 microfarad... A capacitor? You see, I don't know anything about it. These things were brown, 2 pieces. On the net they were blue marked Philips. 

So, things must have been replaced I think .


I stop, sorry for the somewhat longer story. 

Thanks for listening, reading.




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You can't judge much from comparing the volume settings of one component against another. You might remember my talking about them using different laws of attenuation?  Different designers will choose a potentiometer ( that's the volume control) that works in a different way depending upon the amplifier that they expect a preamp to partner , the anticipated sensitivity of the likely loudspeaker, likely source components etc.


Most volume controls spend part of their rotation simply attenuating the incoming signal. Amplification only starts at a point where it is anticipated by the designer that the maximum output from the source will need to be increased to produce a sensible output from the amplifier. He may, for example,  expect the source to be a CD player using the standard 2V output for a recorded signal of 0dBfs ( that means  zero decibels full scale - the maximum recorded level on a digital source) and choose the potentiometer with that in mind. However it may be that the source in practice provides only 1 volt output for 0dBfs or, say, a larger 4 volts (or any other reasonable number). It is really the differing output levels of differing sources that make volume controls necessary in the first place.


Furthermore the way that the control increases/reduces attenuation or amplification is often not constant across all points of its travel. Some designers may choose a volume control that gives a large increase in level for each degree of rotation  at the beginning of the control's travel but with decreasing amounts the nearer it gets to maximum. Or they may choose one that gives an equal amount of change for each degree of travel across its entire rotation. 


If two amplifiers are identical in all other respects and zero output is at the bottom of the rotation range  for both i.e. at 6 o'clock  ( which is pretty common)  then you may think that the one that allows, say,  a 2v output with the volume control turned all the way round to to 3 o'clock is less powerful than  one that provides the same output at 12 o'clock or even 9 o'clock . But, in fact, in this example they are the same. Only the choice of volume potentiometer and the manner in which it applies attenuation is different.


If I knew of an book on electrical theory that serves  to help understand audio electronics then I ought to read it myself 🤔. I do quite like the Robert Harley book The Complete Guide to High Fidelity which has some good sections on the basics of audio. However I do not know when it was last updated so it may now be somewhat out of date.



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Sorry, this should have been a new post.




got a Sony DCT-790 DAT recorder.

the Damned Thing (DAThing) won’t record.

i got the dct-690 and the best 57ES. Still it hitches.

I tried analog, optical, coaxial... nothing. 

I fear the AD DA converters are dead.

Piece of crap seller. To sell junk, a dutchman of course.

all I do now is using him as a DAC, instead of DAT. 1 letter makes a lot of difference.

But I got Musical Fidelity M1 DACs, so a shame to pass the M1 for a DAC inside a Sony DAT.

i opened up the machine but really I got no technical expertise to say of see anything wrong with it. 


Ok. All suggestions are welcome.




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I think that you are right. This should be a new post or I doubt if everyone (or even anyone) who may have any advice for you will find your question.


All I recall is that DAT machines were renowned for unreliability in their day.

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3 minutes ago, PAR said:

I think that you are right. This should be a new post or I doubt if everyone (or even anyone) who may have any advice for you will find your question.


All I recall is that DAT machines were renowned for unreliability in their day.

DATs are, like Cassettedecks en DCC machines delicate. In the case of DATs znd DCCs you have of course the ADC conversion. The recording mecanism does not use heads or capstans but rather a delicate wheel , or double even, second in case of an erasure I guess, TOL. The surface is about 5 milimeters wide and The tape is teared out of its cabinet to pass the wheel were I suppose like harddisk, it magnetises bits on to the tape thereby becoming a digital tape.

Still TOL, or the surface has been demagnetised whatever the source or consequences.

Now, I might be wrong, as it says to hold AD and DA converters.

coming in optical. The DA may convert the sp/dif signal into an analogue one and record it on the tape. 

And you get an analogue tape. Not logical.

i think the ADs convert Analogue signals to digital and record it digital on the tape.

When using optical or coaxial the recording can pass directly.

The DA is then used at playback, like a DAC.

It is for any reason called a Digital Audio Tape, otherwise you can as well use a normal cassette.

So, in case nor the Analogue nor the direct optical or coaxial gives nothing,

something must go wrong in the recording phase.

well, all said. He became a DAC.


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