Audiosciencereview.com/. legit?

[Speedskater]

There is no correlation between Amir’s tests at overloading levels and sound quality of a particular device, and other similar devices.

So?
Stereophile tests line outputs into a 600 Ohm load. Almost no hi-fi components are designed to work into a 600 Ohm load, a 10,000 Ohm load is typical in hi-fi equipment.
Stereophile and Amir are free to test equipment under conditions (and using methods) not specified by the manufacture.

 

[PENG]

You are talking about the overloading limits again. The solution is simple - for high power speakers with low sensitivity just use more powerful amps with higher sensitivity. This case is an exception though.

You are talking about the overloading limits again. The solution is simple - for high power speakers with low sensitivity just use more powerful amps with higher sensitivity. This case is an exception though.

No I wasn't talking about overloading at all, just peaks from movies and even music, with high dynamic range. The following links may help if you are interested. No guarantee of accuracy obviously, it is "unofficial" after all but I think it does get us in the ball park. Yes, I picked an extreme case just to illustrate.

https://www.stereophile.com/content/unofficial-dynamic-range-database
http://dr.loudness-war.info/album/list/dr-max/desc

 

[Irvrobinson]

You are talking about the overloading limits again. The solution is simple - for high power speakers with low sensitivity just use more powerful amps with higher sensitivity. This case is an exception though.

I don't agree with either of your statements. For one thing, just to be precise, amplifiers do not have sensitivity per se, consumer amplifiers generally have a fixed gain factor. Personally, I don't like high-gain audio amplifiers (which I'll arbitrarily define as 30-34db) for a variety of reasons, from lowering volume control settings which tends to reduce volume control granularity and performance, to lowering voltage on the line-level interconnects to the amplifier, which increases the likelihood of noise and distortion, which will then be amplified by the 6-8db higher gain factor.

The reason high gain amplifiers exist is (IMO) to cover up for weak or poorly designed line-level outputs from cheap audio equipment. One amplifier I admire, the Benchmark Media AHB2, has a choice of four gain settings. On many pro audio amplifiers there are gain controls (really just a potentiometer in a circuit that pads down voltage from high-output sources). So while there are choices one can make by amplifier gain factor, that seems like a poor way to choose an amplifier.

While I'm not typical of people who post here, I don't consider myself a rare exception, and I have a large listening room (>8000 cuft) and I like to listen to well-made recordings of acoustic instruments at realistic volumes. Considering how much heat my 28db gain ATI AT3000 amplifier radiates (quite a bit) when I'm in a realism mood, I think the Benchmark DAC3L I use to drive it is probably getting some good exercise too (especially considering that I split each XLR output channel twice). Good line-level pre-amp stages are not rocket science, so using a high-gain amplifier as a bandage for poor line-level design doesn't strike me as a good idea, especially when there are numerous good choices on the market.

 

[PENG]

If you will take a look at the datasheet of NJU72343, you will see the following: AC characteristics: Maximum output voltage min 3.6Vrms, typ 4.2Vrms, max -. Those are the limit of tolerance regarding the maximum output voltage of the referred by you component.

It is exactly what I am talking about.

I re-read your original post and didn't see anything about "limit of tolerance..." You did say "Amir tested 8805 at 4V RMS output while the manufacturer’s manual clearly stated that the max output voltage is 2.4V RMS. ", that was false and I thought you subsequently agreed but I guess I misunderstood.

thus we have a chance that some units will have these components with 3.6Vrms-3.95Vrms maximum output voltage, correct?

I highly doubt the 3.6 Vrm - 4.2 Vrms are tolerance values. If they are, the data sheet would have said so, and for IC chips, such wide/huge tolerance would be totally unacceptable imo. The difference may be from different test conditions, such as test load impedance, rail voltage etc., but I would be guessing as the datasheet is not clear about it. Regardless, it is irrelevant to our original discussion of whether the specified 1.2 V/2.4 V pre out voltage are "maximum output". I say it is not, based my understanding of the schematics and relevant datasheets, and most importantly, measurements by Gene and Amir. If you still insist those are "maximum" output, we'll just have to agree to disagree.

 

[ProFan]

Amir gets the largest fraction of his test samples from site members, not manufacturers

OK, then it explains the high amount of previously praised in other sources units with low SINAD per Amir’s measurements.
If he would receive such units from manufacturers, who know his personal “style” of testing, most probably the supplied units would be pre-tested and pass similar tests performed using the same AP555. In case of 8805 it is possible to find a unit with NJU72343 (just an example) which has a typical maximum output voltage at 4.2Vrms, this unit will obviously perform better (no clipping) being tested at 4.126/4.130 Vrms and the SINAD in final results can be improved significantly. Don’t you think so?

 

[ProFan]

I don't consider myself a rare exception, and I have a large listening room (>8000 cuft)

Hmm, how many people out of 1000 have >8000 cuft listening room? 1, may be 2? Is 0.1% or may be 0.2% a “rare exception” or not?

 

[ProFan]

I re-read your original post and didn't see anything about "limit of tolerance...

Tolerance in used by a manufacturer components can create difference in testing at the border level of clipping,

How about this?

I highly doubt the 3.6 Vrm - 4.2 Vrms are tolerance values

Unfortunately the server doesn’t allow me to post links yet. But I believe you will be able to find the datasheet (google for it). You do not need to believe me or not, just look at the datasheet, and if you can read them, you will see. It’s on the page 4 in the section “AC characteristics”.
If you can not, google “how to read the data sheets of components”.

 

[lovinthehd]

How about this?

Unfortunately the server doesn’t allow me to post links yet. But I believe you will be able to find the datasheet (google for it). You do not need to believe me or not, just look at the datasheet, and if you can read them, you will see. It’s on the page 4 in the section “AC characteristics”.
If you can not, google “how to read the data sheets of components”.

You can always just put the url in your post (and think there's a thread somewhere just to pump up your post count), then it could be copied & pasted....

 

[ProFan]

I say it is not, based my understanding of the schematics and relevant datasheets, and most importantly, measurements by Gene and Amir. If you still insist those are "maximum" output, we'll just have to agree to disagree.

True, such as there is no standard definition for the term “rated output voltage”, we can agree or disagree on somebody’s opinion about it. I agree with those engineer’s opinions (google for quora), they are responses for the question about this term. You disagree? That is fine. Use your own definition - whatever it is.
My definition of the “rated voltage output” is the same as provided by Answer WIKI:
“Rated means the maximum for which the device is intended”. Google “rated voltage output” and you will find the quora’s definition and discussions.

 

[lovinthehd]

True, such as there is no standard definition for the term “rated output voltage”, we can agree or disagree on somebody’s opinion about it. I agree with those engineer’s opinions (google for quora), they are responses for the question about this term. You disagree? That is fine. Use your own definition - whatever it is.
My definition of the “rated voltage output” is the same as provided by Answer WIKI:
“Rated means the maximum for which the device is intended”. Google “rated voltage output” and you will find the quora’s definition and discussions.

Sometimes they simply mean nominal, like a speaker's impedance rating.

 

[ProFan]

Sometimes they simply mean nominal, like a speaker's impedance rating.

True, when the maximum is defined and described, like in example with Yamaha.
If the maximum is not provided, we shall assume the “rated” as maximum.

 

[lovinthehd]

True, when the maximum is defined and described, like in example with Yamaha.
If the maximum is not provided, we shall assume the “rated” as maximum.

You can assume that, from my experience it is not max at all unless it is specified, nor anywhere near max.

 

[Irvrobinson]

I highly doubt the 3.6 Vrm - 4.2 Vrms are tolerance values. If they are, the data sheet would have said so, and for IC chips, such wide/huge tolerance would be totally unacceptable imo. The difference may be from different test conditions, such as test load impedance, rail voltage etc., but I would be guessing as the datasheet is not clear about it. Regardless, it is irrelevant to our original discussion of whether the specified 1.2 V/2.4 V pre out voltage are "maximum output". I say it is not, based my understanding of the schematics and relevant datasheets, and most importantly, measurements by Gene and Amir. If you still insist those are "maximum" output, we'll just have to agree to disagree.

PENG, it would have never occurred to me that a volume control IC would directly drive the pre-out connections, or even drive the internal amplifiers directly. I just assumed there would be op-amp buffers before the connectors or the internal amps. Based on the data sheet, this IC seems to lack the specs you see with most op-amps, like an input impedance spec. Have you seen any schematics that indicate these volume control ICs drive amps or connectors? (Obviously, analog circuit design is not my core expertise.)

 

[Irvrobinson]

If you can not, google “how to read the data sheets of components”.

Just FYI, PENG is an EE and knows how to read a data sheet. He is also, IMO, one of the most knowledgeable and helpful posters on this site, I've never seen him assert anything without knowing what he's talking about. He's also more of a gentleman than I am. So I think you should stow your sarcasm; he deserves better.

 

[ProFan]

So I think you should stow your sarcasm; he deserves better.

I apologize if anybody feels abused, I didn’t mean it.
Here is the link to the data sheet, read it by yourself https://www.njr.com/semicon/PDF/NJU72343_E.pdf

 

[Irvrobinson]

I apologize if anybody feels abused.
Here is the link to the data sheet, read it by yourself https://www.njr.com/semicon/PDF/NJU72343_E.pdf

I've already read it, which why I'm wondering if the output from this IC is meant to be input for an op-amp.

 

[ProFan]

I've already read it, which why I'm wondering if the output from this IC is meant to be input for an op-amp.

Per SM of 8805 the outputs of NJU72343 are connected to the unbalanced outputs through 10 uF cap only, no op amps.
For XLR outputs they use HDAM.

 

[ProFan]

You can assume that, from my experience it is not max at all unless it is specified, nor anywhere near max.

I believe this is the best answer to this question: “what is the rated voltage” https://answers.yahoo.com/question/index?qid=20071022211737AAV05Y0
They say it could be 5-10% gap from the rated level to the maximum ... do you really think 4.13Vrms/2.4Vrms=1.72 or +72% is a proper level of gap?

 

[PENG]

PENG, it would have never occurred to me that a volume control IC would directly drive the pre-out connections, or even drive the internal amplifiers directly. I just assumed there would be op-amp buffers before the connectors or the internal amps. Based on the data sheet, this IC seems to lack the specs you see with most op-amps, like an input impedance spec. Have you seen any schematics that indicate these volume control ICs drive amps or connectors? (Obviously, analog circuit design is not my core expertise.)

Of course, the 8805 has the HDAM buffer. The Demons and Marantz slimlines don't have HDAMs but likely have some sort of simple buffer stage, but unfortunately the schematics do not show that much details. The block diagrams do show the vol IC connected directly to the internal amps and pre outs. Again, I also think there should be a buffer stage, D&M probably hid the details for proprietary reason. Oddly, they have no trouble showing the HDAM circuitry in great details.

I am going to try and PM you something, may be a screen shot.

 

[lovinthehd]

I believe this is the best answer to this question: “what is the rated voltage” https://answers.yahoo.com/question/index?qid=20071022211737AAV05Y0
They say it could be 5-10% gap from the rated level to the maximum ... do you really think 4.13Vrms/2.4Vrms=1.72 or +72% is a proper level of gap?

I'd simply rather have specs that are useful. The pre-out voltage spec usually comes with no actual specification as to what it means. Many measure above 4V prior to clipping, tho.