The Audio Path In Consumer-Grade Products

[Pogre]

To be clear, this is a straw man position of your own making.

If an amp is operating within its proper operating range (that is, if it is operating safely below it's rated power) said amplifier can still sound different to another amplifier operating within it's proper operating range.

The reasons why are well known and established, so I'll point them out to you again so that there is no further confusion :

1) Mismatched volume levels
2) Sighted bias
3) High output impedance leading to irregular frequency response shaping

Proper operating range does *nothing* to prevent the above 3 qualifiers from messing up the amplifiers performance to such an extent that the sound becomes audible to ears.

Really, you only need to screw up 1) and you'll have audible differences all day long. 2) speaks for itself and 3) an amplifier ideally should have a low output impedance or be otherwise load intolerant, therefore a high output impedance destroys any case of the amplifier behaving like an "amplifier" as opposed to a non-defeatable EQ box whose effects vary depending on the speakers connected to it.

So back to this business of amplifiers sounding different even if they fit all the criteria above. Where is the evidence that two amplifiers connected to a particular load sound different if both have low output impedance, are voltage-matched and are both safely operating below their maximum output powers in double blind conditions?

Because that's your contention. So, where is the meat and potatoes to go along with that claim?

Every time I read a post of his it comes across as desperately trying to prove a case, but continually lacks any evidence. All of it is untested hypothesis.

 

[<eargiant]

From your post. Read this again. To state something is factually incorrect and then back that with a citation from a manual of the producer who is trying to sell (and possibly overcharge) a unit, is not something you're suppose to be pleased with.

Some conclusions may be drawn from this, but I'm afraid you'd enjoy very few of them. One might say you're gullible when it comes to marketing content and you couldn't say he is wrong about that.

To even suggest that a manual makes for a sound argument would have to imply that whenever there is a weakness in a unit, the manual clearly states it and, thus, since your manual says this is something great, it has to be great.

All the while, we live in a world where no manual ever directly stated that there's something wrong with the product it refers to. And even when there is, it is extremely carefully disguised as an advice to not use a unit in this way or that way because it wasn't meant for that.

No, no, no. I think you misunderstood my post. You quoted the end of one thought and the start of another. Those were two separate thoughts. I was not using the statement from the user guide as proof of anything. For goodness' sake give me more credit than that.

I only quoted it to show how the manufacturer described the function of the Jump switch which some seemed curious about. I almost left that part out because I knew someone was bound to jump all over it and sure enough I was right. I've offered the schematic for anyone to dissect but so far no takers, here's the block diagram.





The "Flat Amp" itself is a large board with over 100 components on it. Again, the "Jump" switch allows you to bypass it completely. Here is a longer description of the "Flat Amp" section in this Integrated Amp :

"The DC Flat Amp is a differential input formed of Dual-FET and a current source and cascode bootstrapping circuit; a secondary stage of current differential push-pull drive; and an SEPP true complimentary output. A total of 11 FETs and transistors form this ICL/DC flat amp with 14dB gain. It may be switched out if necessary.

The Dual-FET used in the input is actually made of two FETs mounted on a chip...make them an ideal device for the input that also features high input impedance, low noise and high gain. Voltage potentials are never changed by ambient temperature. The second stage push-pull drive forms a circuit of high current supply capability, low TIM distortion and high slew rate."


The "Flat Amp" board.

So think about it, why would the engineers waste all this time and energy to include this entire board inside this Integrated amplifier and allow me to bypass it if I could accomplish the same thing by raising or lowering the volume control (which BTW this Integrated has a master volume as well as two independent L&R power amp level controls and plenty of power).

Does anyone really think that raising or lowering the volume will give the same audible effect as including or removing this entire board from the signal path?

The "factually incorrect" part was referring to PENGs comment about DISTORTION being the reason for the difference in sound. The proof I can offer that there is no meaningful distortion is my integrated on a bench. That 60kHz square wave is just a taste.

 

[killdozzer]

No, no, no. I think you misunderstood my post. You quoted the end of one thought and the start of another.

In this case I do most sincerely apologize. Even if I don't fully agree with you, I don't believe in punching below the belt.

I do give you credit. Perhaps more than you'll know. I mean, I read all of the posts here (not successfully it would seem), even though you appeared to be just another "true believer of marketing".

There's one thing I learned about people on this forum; they're calling "sound improving cables" BS only, and I mean ONLY as long as someone doesn't come up with sound improving cables.

The same goes for the rest of it. And this is where you fall short. You're able to demonstrate the lack and only the lack of bad test results. As for the rest of your claims, you only manage to fight the notion that test results are necessary.

Again, you might consider this as me not giving you enough credit, but I would be careful about calling something science before the possibility of test results. Science in the end has it's method and the method is measuring. One way or the other.

You might say; well this is new or pioneering or the test results will come in. But this is exactly what troubles me. In this type of audio world everything can be hazy but the price. The price is very real. It may not be measurable, and test results may have not yet come in, but the price came on a horse with loud Wagner in the background. And the price is saying; more, more, we want -n thousands of dollars for all these not provable and not measurable attributes of this product. And this is something you accept. As long as you (and others) accept it, you're in no position to ask all those questions like; why would they put it inside and what could motivate them.

I don't even contest the fact that you hear the difference and I most certainly don't contest the fact that you like that difference.

This is what I mind about this approach to audio; you operate and make your decisions under the conditions where you can't prove, test, measure or in any other way be reassured that the difference you hear and like is worth the money asked and the ones asking the money put zero effort in trying to provide way of proving, testing, measuring etc. This is what makes it a hoax even if you like what you hear.

 

[<eargiant]

In this case I do most sincerely apologize. Even if I don't fully agree with you, I don't believe in punching below the belt.

I do give you credit. Perhaps more than you'll know. I mean, I read all of the posts here (not successfully it would seem), even though you appeared to be just another "true believer of marketing".

There's one thing I learned about people on this forum; they're calling "sound improving cables" BS only, and I mean ONLY as long as someone doesn't come up with sound improving cables.

The same goes for the rest of it. And this is where you fall short. You're able to demonstrate the lack and only the lack of bad test results. As for the rest of your claims, you only manage to fight the notion that test results are necessary.

Again, you might consider this as me not giving you enough credit, but I would be careful about calling something science before the possibility of test results. Science in the end has it's method and the method is measuring. One way or the other.

You might say; well this is new or pioneering or the test results will come in. But this is exactly what troubles me. In this type of audio world everything can be hazy but the price. The price is very real. It may not be measurable, and test results may have not yet come in, but the price came on a horse with loud Wagner in the background. And the price is saying; more, more, we want -n thousands of dollars for all these not provable and not measurable attributes of this product. And this is something you accept. As long as you (and others) accept it, you're in no position to ask all those questions like; why would they put it inside and what could motivate them.

I don't even contest the fact that you hear the difference and I most certainly don't contest the fact that you like that difference.

This is what I mind about this approach to audio; you operate and make your decisions under the conditions where you can't prove, test, measure or in any other way be reassured that the difference you hear and like is worth the money asked and the ones asking the money put zero effort in trying to provide way of proving, testing, measuring etc. This is what makes it a hoax even if you like what you hear.

No worries, I have thick skin . Apology accepted.

Your logic is faulty in the line I bolded. If the manufacturer really wanted to increase their profit they would have left the "flat amp" and Jump switch OUT of the design and just extolled the virtues of a short low gain signal path.

One of the things that makes this Integrated amp special is that it allows you to circumvent the "flat amp" pictured above, NOT the fact that it's in there in the first place. The choice that the engineers made to add a simple switch allowing the end user to bypass the entire board did not add much cost to the unit, it's just a switch. What it did add was more flexibility. It wasn't even a big marketing point.

I don't know why you think I'm avoiding measurements. This is an all-in-one Integrated amp so it is easy to measure with the Jump switch ON and with the Jump switch OFF. So in essence, nothing changes except the removal of the "flat amp" and its affect on the signal being amplified. Those two paths WILL measure differently but under a battery of tests (like Gene does) on paper both would look fantastic with or without the "flat amp" to any member of this site.

If this manufacturer had decided to make two separate units instead of one (say model A and Model B) one with the "flat amp" (and it's additional gain) and one without the "flat amp" in the signal path nothing would change post-flat amp (refer to block diagram), the amplification section would be identical. What would change is the signal the amplification section is amplifying. So, because they were designed differently - you would have two Integrated amps that are not feeding the same signal to the speakers (assuming you have the same identical source) no matter how hard you try to adjust the volume knob.

 

[killdozzer]

Your logic is faulty in the line I bolded. If the manufacturer really wanted to increase their profit they would have left the "flat amp" and Jump switch OUT of the design and just extolled the virtues of a short low gain signal path.

It would seem to me this time you were a bit hasty to find flaws in one's logic.

What I'm talking about in my previous post are results, not the chosen method. Manufacturer did what needed to be done.

Let's look at the other end of that transaction. Do you think it's worth it? Yes. Do you even own this amp? Possible. Would you join a forum and defend what they did through 15 pages? Most definitely yes and you did. Did they, through their chosen actions, make you even hard to suspect them of fraud? Again, a firm yes. Would you become a crusader for their cause? You have become. (I still suspect you're directly or indirectly involved in marketing of this product)

So, did they choose the right method? You tell me.

It's all here: As long as you (and others) accept it (the price), you're in no position to ask all those questions like; why would they put it inside and what could motivate them.

It is plainly obvious why would they put it inside.

Just for the sake of not loosing the thread; you did mention several amps, so which one has this 14dB gain? Do you own any of them? Are they more expensive than a Yamaha a-s701?

I don't know why you think I'm avoiding measurements.

This is, again, not exactly what I said. You provide all the negative tests (the ones proving no detectable distortion, at least so far), what you don't provide are the tests that clearly pinpoint audible features that would prove this amp does a better job than a consumer product. So, I said lack of bad test results. But I don't see test results that would in a positive way distinguish this amp from aforementioned "amp that measures good and is within its comfort zone" This is where you start saying "not everything can be measured".

 

[<eargiant]

The amp I've been referring to with the Jump switch is not the Benchmark amp discussed in the article at the start of this thread.

The block diagram, flat amp, Jump switch, and square wave pictures that I posted are all from a Sansui AU-X1 Integrated amp (also in my avatar). Yes, I own one that has been fully restored. It is a consumer unit manufactured in 1980, yes 1980 .

The only reason I brought it up was to specifically mention that an engineers choice of gain that is going into the same amp section of an Integrated unit is enough to produce a different output that cannot be equaled with the volume control. It's the perfect amp to show that making a change within the signal path that is going into an same amp section of an integrated unit will affect the signal that is coming out of the amplifier section to the transducers. These things can be measured. I'm sure that based on the measurements of either path there is no member here that would hesitate recommending the unit based on reading the graph. It will measure well no matter how you slice it.

Point being, this is why I always wonder how people can be so sure that one integrated amp (or receiver, AVR, all-in-one, call then what you want) will offer no appreciable sound benefit over another if they both measure well.

Let me ask it this way. Which Jump switch setting will make my Sansui AU-X1 sound like my Yamaha A-S801? Is it the ON or OFF setting?


Background info: The AU-X1 amps are not common but they are out there. They have been restored and and tested by highly skilled individuals far more knowledgeable than myself and many on this forum. These are individuals that can read, understand, design & modify audio circuits as well as test audio equipment. I have seen them work on and display their technical mastery on these rare integrateds in countries like Germany, Japan, Croatia, Netherlands, Australia, Chile, England and the United States to name a few. So many talented individuals out there and the consensus when they are done with it is unanimous - amazement at how this amplifier measures and performs.

 

[Swerd]

The only reason I brought it up was to specifically mention that an engineers choice of gain that is going into the same amp section of an Integrated unit is enough to produce a different output that cannot be equaled with the volume control. It's the perfect amp to show that making a change within the signal path that is going into an same amp section of an integrated unit will affect the signal that is coming out of the amplifier section to the transducers. These things can be measured.

Then it would also be the amp to use in a demonstration of whether or not it can be heard. This would have to be a controlled listening test using human listeners. No electronic bench measurement, alone, can provide that evidence.

EDIT: I omitted an essential phrase, under blind conditions. "This would have to be a controlled listening test, using human listeners, under blind conditions.

 

[lovinthehd]

Just what is a "flat amp" and its "jump switch", though?

 

[Pogre]

I can't believe this thread is still going...

 

[<eargiant]

Then it would also be the amp to use in a demonstration of whether or not it can be heard. This would have to be a controlled listening test using human listeners. No electronic bench measurement, alone, can provide that evidence.

Agreed. I'm confident all of you will hear the difference. 100% confident.

EDIT for Swerd: Yes, I'm 100% confident you'd all hear the difference even under blind conditions. "Blind" should be easy because there's only 1 integrated amp involved. The only give away would be if the listener has good enough vision to see if the switch is in the in or out position. The switch is small and should be easy to cover in case someone tries to peek .

 

[M Code]

Just what is a "flat amp" and its "jump switch", though?

Inside an integrated amplifier or preamplifier is a circuit board usually known as 10X that also included the tone controls & loudness feature. The jump switch simply switches this in/out of the signal path. End result is the overall gain is thus decreased significantly requiring the volume control to be increased to bring the average listening level up. This feature was common in a series of Sansui integrated amplifiers sold in the 80s', if the source input was high level like from a CD player or tape deck typically quite hot switching in/out the jump circuit the end source was still listenable even though its level was lower. However if the source was a low level like from an MM phono typically the end gain was too low resulting in an unusable listening level...

Just my $0.02...

 

[<eargiant]

Inside an integrated amplifier or preamplifier is a circuit board usually known as 10X that also included the tone controls & loudness feature. The jump switch simply switches this in/out of the signal path. End result is the overall gain is thus decreased significantly requiring the volume control to be increased to bring the average listening level up. This feature was common in a series of Sansui integrated amplifiers sold in the 80s', if the source input was high level like from a CD player or tape deck typically quite hot switching in/out the jump circuit the end source was still listenable even though its level was lower. However if the source was a low level like from an MM phono typically the end gain was too low resulting in an unusable listening level...

Just my $0.02...

That's right. The only difference is that unlike the AU-919 on the AU-X1 there are no tone controls or loudness contours so the flat amp is solely about gain not coloration.

 

[lovinthehd]

Inside an integrated amplifier or preamplifier is a circuit board usually known as 10X that also included the tone controls & loudness feature. The jump switch simply switches this in/out of the signal path. End result is the overall gain is thus decreased significantly requiring the volume control to be increased to bring the average listening level up. This feature was common in a series of Sansui integrated amplifiers sold in the 80s', if the source input was high level like from a CD player or tape deck typically quite hot switching in/out the jump circuit the end source was still listenable even though its level was lower. However if the source was a low level like from an MM phono typically the end gain was too low resulting in an unusable listening level...

Just my $0.02...

Is it analogous to a typical gain adjustment electronically (e.g. dial type like in Killdozzer's example in post 265, or even a digital input level adjustment in a modern pre/pro-avr), or a different beast? I'd never heard the term flat amp and wondering just how relevant this type of gain "adjustment" is in regards to typical use in current offerings.

 

[PENG]

Inside an integrated amplifier or preamplifier is a circuit board usually known as 10X that also included the tone controls & loudness feature. The jump switch simply switches this in/out of the signal path. End result is the overall gain is thus decreased significantly requiring the volume control to be increased to bring the average listening level up. This feature was common in a series of Sansui integrated amplifiers sold in the 80s', if the source input was high level like from a CD player or tape deck typically quite hot switching in/out the jump circuit the end source was still listenable even though its level was lower. However if the source was a low level like from an MM phono typically the end gain was too low resulting in an unusable listening level...

Just my $0.02...

My Marantz SC-7 preamp, also from the late 70's early 80's, has that kind of" flat amp switch" that can be switched in and out. As you said, that kind of flat amp is more about tone control and loudness. It functions a tiny bit like the modern AVP/AVR's "pure direct" feature. Same name different purpose.

 

[M Code]

My Marantz SC-7 preamp, also from the late 70's early 80's, has that kind of" flat amp switch" that can be switched in and out. As you said, that kind of flat amp is more about tone control and loudness. It functions a tiny bit like the modern AVP/AVR's "pure direct" feature. Same name different purpose.

The SC7 preamp was based on the 3650...
The Marantz series 7 components were based on a select marketing distribution plan to audio specialists. The standout feature on the SC7 is its phono MM circuit it will can swing an output voltage up to 9V RMS, also the same basic phono MM circuit was used in their monster receiver 2500 & 2600.. However unlike the Japanese competitors the series 7 components were mainly designed in the USA (Chatsworth, CA) by a USA team made up of key engineers from JBL/Harman Kardon.

Just my $0.02...

 

[<eargiant]

A "Tone Defeat" switch should not be confused with a "Jump" switch. The critical difference is -Gain.

If it's the Marantz SC7 I'm thinking about, it has a "Tone Defeat" switch. This is NOT the same as a "Jump" switch. The only similarity is that it allows you to bypass something. I have owned several amps with the "Tone Defeat" switch.

The "Tone Defeat" switch bypasses the tone control board (as stated-like "Pure Direct"), this is a very common feature. If the tone controls are set to "Off" ("flat" or "0") and you engage and disengage the "Tone Defeat" switch you would normally not hear any appreciable or dramatic change in sound unless the tone board or circuit is defective. The "Tone Defeat" switch does not alter the gain of an amplifier in any way.

• On a unit like the Marantz SC-7 which has tone controls, the "Tone Defeat" switch serves only one function:

1) It bypasses the tone controls.​

• On a unit like the Sansui AU-919 which has tone controls, the "Jump" switch serves two functions:

1) It bypasses the tone controls (like a "Tone Defeat" switch).​

2) It bypasses the gain of the Flat Amp.​

• On a unit like the Sansui AU-X1 which does not have tone controls (there is no need to bypass what is already not there) the "Jump" switch serves only one function:

1) It bypasses the gain of the Flat Amp.​

 

[PENG]

A "Tone Defeat" switch should not be confused with a "Jump" switch. The critical difference is -Gain.

I don't see anyone confusing a tone defeat switch with your Sansui's jump switch. Mr. Code clearly described how the SC-7's flat amp switch works, and that is different than the one you have on your amp.

If it's the Marantz SC7 I'm thinking about, it has a "Tone Defeat" switch. This is NOT the same as a "Jump" switch. The only similarity is that it allows you to bypass something. I have owned several amps with the "Tone Defeat" switch.

MCode and I are talking about the flat amp switch that the SC-7 also has. In fact the SC-7 has quite a few switches including a tone defeat switch. We know what the SC-7's is for, as I said, same name different function, and yes MCodes's right, it does affect the gain too.

 

[<eargiant]

I don't see anyone confusing a tone defeat switch with your Sansui's jump switch. Mr. Code clearly described how the SC-7's flat amp switch works, and that is different than the one you have on your amp.



MCode and I are talking about the flat amp switch that the SC-7 also has. In fact the SC-7 has quite a few switches including a tone defeat switch. We know what the SC-7's is for, as I said, same name different function, and yes MCodes's right, it does affect the gain too.

Because you said what is underlined below which can confuse some. A flat amp alone is usually about gain, not tone or loudness contours. I'll take a look at Block Diagram of your SC-7 but my guess is that the tone boards are separate. My guess is that your "bypass" operates like the Jump on the AU-919 in my example. The point being that some might think bypassing the flat amp is about tone control based on what you said below .

"My Marantz SC-7 preamp, also from the late 70's early 80's, has that kind of" flat amp switch" that can be switched in and out. As you said, that kind of flat amp is more about tone control and loudness. It functions a tiny bit like the modern AVP/AVR's "pure direct" feature. Same name different purpose."

I'm not sure but I think your flat amp bypass switch drops the gain by -10 db. Not quite the -14 dB drop that mine has but have you ever carefully experimented with it while hooked-up to the same amp?

Marantz recommended keeping it on the normal setting otherwise "For high-fidelity playback or for checking the equipment, switch it to the bypass position." It sounds like the boys from JBL/Harmon Kardon agree with me that there is a real difference when a change like this is made to the signal path .

 

[ski2xblack]

I can see the rationale, if the added gain was used to drive studio gear, for example. That's assuming this extra gain is applied in the pre- section and available on pre-outs.

It's still just a gain thing, though. It won't cause tonal shifts or anything of the sort.

 

[M Code]

To fully understand the situation about jump switch, tone defeat, direct switchable functions one has to go back thirty years to the early-mid 80s..
As the digital CD & DAT formats were introduced and related specifications such as THD, headroom, dynamic range and SNR became popular surpassing those of the typical analog source specifications there was an increasing awareness and brand marketing emphasis for a more purist, perfectionist design approach with improved specifications..

The big brand marketing push was for lower THD, higher SNR specifications by having defeat switch capability when a component was under a magazine lab test these could be switched out and better specifications could be disclosed. Whether or not there was any sonic improvement is another discussion topic..

Just my $0.02...