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Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.


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As those interested collectively in audio, we are capable of on many an occasion buying equipment, that we think might provide either something different, ...or better planned to indeed leap ahead &put us firmly on the road to a better audio experience.  If in the latter group,  we need to know a bit more, than just our bank balance. 

 

The first amazing part ( of the topics gamut ) is the  jfet , it is a small signal device comprised of a source pin, a drain pin and a gate. a study of it finds that it has very good properties for audio.   It is a device that allows current equally well in either direction, as it has a structure which contains an n type channel, embedded in a p type silicon substrate, meaning the drain may be positive or negative with respect to the source..  Simply put it does not invert or change the phase of a incoming or later audio signal, so what is audio signal, is left intact, but just amplified. 

 

You will find the jfet in many circuits, like microphones, tuners,  in phono preamps, and in good amplifiers.   You can research hifi equipment schematics to find how many here: https://www.hifiengine.com/

 

 

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You started a thread entitled "Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.".   My comment was directed to that.      My advice remains - seek proper i

Very well said. This very thing is very often used in marketing, for product differentiation in the market place. Some new buzz-word is introduced and is backed by a very valid technical arg

The internet is an amazing source of information.  Unfortunately not all of it is true.    There's one hell of a lot of misinformation being thrown around with zero accountability for poten

7 hours ago, stereo coffee said:

It is a device that allows current equally well in either direction

Are you sure about this? I was always under impression that only some JFETs are like that and most do not have that capability.

 

7 hours ago, stereo coffee said:

as it has a structure which contains an n type channel, embedded in a p type silicon substrate,

or the other way round

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Jfet...............the long lasting valve.

Although, I blow the jfet preamp in my guitar amp more often than the valve preamp.

(I'm sure it's the heat from the valves)

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56 minutes ago, rockeater said:

Are you sure about this? I was always under impression that only some JFETs are like that and most do not have that capability.

 

or the other way round

,Refer to Siliconix  Designing with field effect transistors McGraw Hill  page 10. The p channel jfet however does have differences, being a change in the polarities, and less channel conductance, making the n channel, usually the preferred device. 

 

 

 

 

Screenshot from 2021-02-01 22-43-20.png

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  • 2 weeks later...

Our next look at parts is the rectifier and variations, that arguably can benefit audio . Some readers will be familiar with the circuit the bridge rectifier, as it is an extremely common circuit, but perhaps unaware there are variations worthwhile exploring too.

 

This article reveals one method of achieving a controlled bridge rectifier   https://simple-circuit.com/arduino-controlled-bridge-rectifier/

 

Another device the LT4320 similarly improves upon the standard bridge rectifier by providing less heat and greater efficiency, when paired with N channel mosfets;   https://www.analog.com/en/products/lt4320.html

 

These devices certainly improve the efficiency and unwanted ripple of rectification, and will greatly improve audio of circuits they attach to 

 

Where however, instead the known actual load as a current sink or drive, rather than as a source of voltage   from the supply is used,  opens many new chapters of how implementing such circuits can benefit audio. As example the  current driving of loudspeakers https://www.current-drive.info

An early example of a manufacturer thinking about the load in a power supply is the AR amplifier  https://www.hifiengine.com/manual_library/acoustic-research/amplifier.shtml

 

 

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Assisting good audio reproduction, is concept to have strategy not to add reactance unnecessarily.  Reactance is defined as:

https://en.wikipedia.org/wiki/Electrical_reactance

 

"In electric and electronic systems, reactance is the opposition of a circuit element to the flow of current due to that element's inductance or capacitance. Greater reactance leads to smaller currents for the same voltage applied. Reactance is similar to electric resistance in this respect, but differs in that reactance does not lead to dissipation of electrical energy as heat. Instead, energy is stored in the reactance, and later returned to the circuit whereas a resistance continuously loses energy "

 

It would be interesting to define or discuss the correlation of reactance to distortion. Noting resistance itself is not ultimately perfect either, but is for audio purpose ( if we wish to explore what recordings actually contain) ,  arguably far more agreeable than adding any reactance.    Its ironic we search for cables that have minimum capacitance and inductance, but sometimes ignore these same properties in between our source and power amplifier.

 

To avoid adding reactance such as can occur where the input sensitivity differs at a power amplifier input, different to the level  from the source  ,  it is useful to know about actual levels that source equipment has on their outputs, this is not levels that equipment itself can attain, rather the levels that media mediums played on equipment actually contain. A important distinction that realizes normal operation that we can expect in every day use.      Nominal line level is 0.315v RMS  and is compared to other ways of expressing the same value below:

https://en.wikipedia.org/wiki/Line_level

 

You can test your own media mediums using Audacity for their compliance to consumer line level, image shows a Flac file with Sonar the ever inventive Swiss band playing flat out, we can see the RMS voltage level is nominally, pretty well exactly as the standard advises.  

https://www.audacityteam.org/

 

We should IMO see all power amplifiers with for consumer use with sensitivity no greater than 500mv RMS , study as much as we can about resistance and attenuation , including impedance bridging principles. Our objective IMO should be to match the media source level,  and at all cost, ( usually much less financial cost)   avoiding unneeded, and unwanted reactance in between.

 

 

 

 

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7 hours ago, stereo coffee said:

It would be interesting to define or discuss the correlation of reactance to distortion. Noting resistance itself is not ultimately perfect either, but is for audio purpose ( if we wish to explore what recordings actually contain) ,  arguably far more agreeable than adding any reactance.    Its ironic we search for cables that have minimum capacitance and inductance, but sometimes ignore these same properties in between our source and power amplifier.

I say who needs this tech-speak and electronic mumbo-jumbo when the new $1000 set of cables with fat bulge in the middle make treble smooth and they have a great review in Stereophile?

I strongly disagree with your assertion that we should avoid reactance (both capacitive or inductive).

Adjusting frequency response with reactive cables is a great way of achieving our preferred sound ever since the 90s, when the last graphic equaliser disappeared.

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Thanks for your input,  there are a handful of forum members, who have dedicated considerable time and skill to the study of cables, as example @Southerly ,  may wish to address your comments.

 

 

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Further to our topic about matching sensitivity, a good power amplifier manufacturer, will publish detail about how input sensitivity relates to output power and load resistance. We can see if input sensitivity is too high- lets say 2 volts RMS we are never going to achieve the full output,

of the amplifier as the media we play is at RMS v,  consumer line level, which needs to be similarly matched to the power amplifiers RMS v sensitivity

 

This arises as power amplifiers are simply servants to their input signal. We can see in the example below that 50 watts output is achieved into a 8 ohm load, when the input sensitivity is 0.375v RMS. If however sensitivity was 2v RMS,  we can anticipate that 5.3 times less power would be available which infers our 50 watt amplifier is miserably, as a result of not paying attention to input sensitivity figures actually only capable of 9.38 watts !!! . This is why input sensitivity IS one of the most important figures to observe when choosing power amplifiers.      Below is such a graph:

 

Screenshot from 2021-02-19 12-50-30.png

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Chris,

this sensitivity issue is something new to me and very, very interesting. Please correct me if I'm wrong - the normal output for a CDP is 2 volts the actual output voltage for my Marantz CD6007 is 2.4V. I plan to bi-amp in the near future but for now I will be using a Hypex UCD 180 HG. Input voltage up to 60V but looking through the paperwork I cannot find an input sensitivity rating. I will look to see what the output sensitivity is for my Talk Electronics  MC3  phono stage is.

 

All audio forums should have a checklist for essential info like this but none do. It is either presumed that forum members have this technical info or is just ignored. 

 

Re. cables - flame wars and arrogant klootzaken that know everything can carry on their negative barrage because no one has ever to my knowledge actually presented cast iron proof of anything regarding signal flow and integrity, all of which will be dependant on conductor type,  gauge and quality, dialectric type or the effect of connector design and function and type of solder or clamping used.

 

To my knowledge the only branch of science that can give definitive answers has to be able to measure extremely small amounts of electrical energy and the only one I know of is particle physics since they deal with the world of micro energy.  Being able to measure effectively levels of micro energy, can the integrity of the electrical signal be measured to confirm what percentage of the signal has maintained integrity and how much has been corrupted.

 

If such tests could be carried out by experienced personnel then this would finally end all the negative and time wasting  flame wars  on cables. It would also wipe out a lot of companies spouting complete b/s and techno babble.

 

I'm thinking about shielding - good or bad / conductor type, gauge and quantity / dialectric and connector design. Only equipment that can measure extremely small variations would be of use and AFAIK that will be those working in particle physics. So,, anyone with good connections to physics departments in Unis or tech colleges please use your connections to see if a dept. will bite. When I think of the money wasted having to do experiments myself when  cast iron knowledge from actual trials carried out and reviewed not 'received wisdom' / sclerotic thinking or we've always done it this way mentality holds sway. 

 

Is a  box really the best way to hold equipment, why no attempt to create convection currents and or computer type fans to lower internal temps. when since the 50s' white papers have been written about the benefit of seriously lowering temps of resistors,caps etc.

 

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13 hours ago, Southerly said:

Chris,

this sensitivity issue is something new to me and very, very interesting. Please correct me if I'm wrong - the normal output for a CDP is 2 volts the actual output voltage for my Marantz CD6007 is 2.4V. I plan to bi-amp in the near future but for now I will be using a Hypex UCD 180 HG. Input voltage up to 60V but looking through the paperwork I cannot find an input sensitivity rating. I will look to see what the output sensitivity is for my Talk Electronics  MC3  phono stage is.

 

All audio forums should have a checklist for essential info like this but none do. It is either presumed that forum members have this technical info or is just ignored. 

 

Re. cables - flame wars and arrogant klootzaken that know everything can carry on their negative barrage because no one has ever to my knowledge actually presented cast iron proof of anything regarding signal flow and integrity, all of which will be dependant on conductor type,  gauge and quality, dialectric type or the effect of connector design and function and type of solder or clamping used.

 

To my knowledge the only branch of science that can give definitive answers has to be able to measure extremely small amounts of electrical energy and the only one I know of is particle physics since they deal with the world of micro energy.  Being able to measure effectively levels of micro energy, can the integrity of the electrical signal be measured to confirm what percentage of the signal has maintained integrity and how much has been corrupted.

 

If such tests could be carried out by experienced personnel then this would finally end all the negative and time wasting  flame wars  on cables. It would also wipe out a lot of companies spouting complete b/s and techno babble.

 

I'm thinking about shielding - good or bad / conductor type, gauge and quantity / dialectric and connector design. Only equipment that can measure extremely small variations would be of use and AFAIK that will be those working in particle physics. So,, anyone with good connections to physics departments in Unis or tech colleges please use your connections to see if a dept. will bite. When I think of the money wasted having to do experiments myself when  cast iron knowledge from actual trials carried out and reviewed not 'received wisdom' / sclerotic thinking or we've always done it this way mentality holds sway. 

 

Is a  box really the best way to hold equipment, why no attempt to create convection currents and or computer type fans to lower internal temps. when since the 50s' white papers have been written about the benefit of seriously lowering temps of resistors,caps etc.

 

Hi Stuart

Whilst indeed the equipment has 2v capability, the actual media we enjoy has nominal RMS voltage output no greater than +/- 0.315V RMS,  so that is all any player outputs,  when playing a CD, ...it does not go any higher.  Whilst  the peak level is greater ,  all we need to do is pay attention to matching RMS level of media, to be close to amplifier input sensitivity also quoted in RMS , ... to enjoy full output, rather than only partial output from power amplifiers. 

 

There will many on the forum who won't believe this, so let's show an example.  Here is King Crimson's Red, the RMS level is in light blue, the peak is in darker blue, we can see at the end of the piece the RMS level is highest, but does not exceed 0.315v RMS 

 

Another example is Quad the UK amplifier manufacturer, who since 1967 have manufactured power amplifiers with generally sensitivity of

no greater than 0.5v RMS, the exceptions being the 306 with 0.375mv, and 909 with as I recall 0.775v RMS  , as they stringently followed the line level nominal guidelines.  Owners of the 306 will find it never overloads on signal input.

 

As always a fascinating, and passionate insight into the physics of cables. 

 

 

 

 

 

 

 

 

 

 

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I would suggest anyone really wanting to know about these things, should find some proper references and textbooks to study, maybe even do a structured course, and not rely on opinions and half-understood concepts that can be found around a lot of the Internet.

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25 minutes ago, aussievintage said:

I would suggest anyone really wanting to know about these things, should find some proper references and textbooks to study, maybe even do a structured course, and not rely on opinions and half-understood concepts that can be found around a lot of the Internet.

Much easier, just have a look for yourself, you can measure actual RMS output of your media,  using audacity    https://www.audacityteam.org/

which is free. If you find anything different publish it here please.

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17 minutes ago, stereo coffee said:

Much easier, just have a look for yourself, you can measure actual RMS output of your media,  using audacity    https://www.audacityteam.org/

which is free. If you find anything different publish it here please.

 

 

Clearly you misunderstand. I didn't respond to, nor quote from,  that post of yours about line levels, but to the whole thread.   You won't learn basic electronics from Audacity.

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7 minutes ago, aussievintage said:

 

 

Clearly you misunderstand. I didn't respond to, nor quote from,  that post of yours about line levels, but to the whole thread.   You won't learn basic electronics from Audacity.

Maybe tackle the actual topics post's contributed content instead,   @Marc may wish to remind us of the forums ethos, enabling us to get along well with forum members, at all time.

 

If you have differing opinion about one topic or another then say so.  I am sure many, including myself, would be interested  and welcome your viewpoints. Indeed create discussion as well, as there is plenty of scope in the topics description. 

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9 minutes ago, stereo coffee said:

 

Maybe tackle the actual topics post's contributed content instead,   @Marc may wish to remind us of the forums ethos, enabling us to get along well with forum members, at all time.

 

If you have differing opinion about one topic or another then say so.  I am sure many, including myself, would be interested  and welcome your viewpoints. Indeed create discussion as well, as there is plenty of scope in the topics description. 

 

 

You started a thread entitled "Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.".   My comment was directed to that.   

 

My advice remains - seek proper information from reliable sources.   Lots of the problems this hobby experiences are from people believing misinformation found on the Internet.

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7 minutes ago, aussievintage said:

 

 

You started a thread entitled "Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.".   My comment was directed to that.   

 

My advice remains - seek proper information from reliable sources.   Lots of the problems this hobby experiences are from people believing misinformation found on the Internet.

 

 

We have thus far looked at  The jfet , alternatives to the bridge rectifier,  avoiding reactance in signal paths, how sensitivity relates to power amp output and resistive load, we also looked at media content actual output. &  Stuart contributed fascinating discussion of cables

 

The topics raised have each received considerable care to present to you, drawing from proper sources:

 

Second Edition Designing with Field Effect Transistors Siliconix Inc McGraw hill publications

Analog. com

Wikipedia

Quad Electrocoustics ( graph of power amp response )

Current driving of Loudspeakers Esa Meriläinen

 

 

 

 

 

 

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aussie vintage,

why don't you supply factual test proven info. You say 'seek proper information from reliable sources' - what is proper information - what are reliable sources. I call that waffle with not a single fact stated. 

 

Proper information - supply dates or is it from the past. Just what are reliable sources - what experiments, why are'nt you supplying data. It seems to me that you are hiding behind waffle and b/s. 

 

If you have actual repeatable data let's have it. One of the first things I learned when I bought a well written book for the layman on particle physics was that - all systems tend toward self perpetuation. Since particle physics deals with the very basis of life, everything follows on from  that right up to the monkey that fell out of a baobob tree x number of years ago in the Rif valley.

 

No organisation can escape this fact be it religious, political, scientific or cultural. In the UK we have the farce in our parliament of referring to MPs as 'my right honourable gentleman/woman FFS this is from the 18th century. Why do lawyers go on wearing ludicrous wigs from the 17th century - do you have this insanity in Oz as well. Priests wear frocks from the 14th century. Listen to scientists tearing each other to pieces for or against theories.

 

Why is so much audio equipment put into rectangular boxes that do nothing or little to lower temperatures inside these silly irrational boxes and this has been happening for decades - the inertia theory. I with a Dutch friend some 12 years ago bought into a Chinese made hybrid h/amp  using Toshiba mosfets, they and power resistors created a lot of heat - not good, so we bought computer fans to use below the h/amps with the base plate removed and with slot ventilation on the top plate meant it was easy for the heat generated to escape. 

 

Putting this info on a well known audio forum got the response that mosfets perform  better when hot - I asked for proof - no response. There is far too much of this in the audio world.

 

Putting passive x/overs inside speaker cabinets - insane, totally insane. It is obvious to an idiot that the x/overs whether passive or active should be external to all the pressure waves and vibration inside a speaker cabinet. This stupidity has been going on for decades why - the inertia affect that has sod all to do with sound science, in fact the complete opposite.

 

 

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The internet is an amazing source of information.  Unfortunately not all of it is true.  :(

 

There's one hell of a lot of misinformation being thrown around with zero accountability for potential consequences.  Like some of the electronics channels where the vloggers / presenters have a very distorted and erroneous view on basic established electronics concepts.  However no matter how often you bring the errors to their attention the BS continues. Dare to challenge their assertions and risk incurring their wrath.  Hey but 100k+ subscribers can't be wrong - or can they?  🙄

 

My advice for what it is worth, is to stick to text books for the basics so you can build an understanding of the concepts underpinning the subject, then armed with a good background on the subject it becomes significantly easier to sort the gurus from the BS artists. 👍

 

Cheers,

Alan R.

Edited by Monkeyboi
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2 hours ago, Monkeyboi said:

My advice for what it is worth, is to stick to text books for the basics so you can build an understanding of the concepts underpinning the subject, then armed with a good background on the subject it becomes significantly easier to sort the gurus from the BS artists

Absolutely

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5 hours ago, Monkeyboi said:

The internet is an amazing source of information.  Unfortunately not all of it is true.  :(

 

There's one hell of a lot of misinformation being thrown around with zero accountability for potential consequences.  Like some of the electronics channels where the vloggers / presenters have a very distorted and erroneous view on basic established electronics concepts.  However no matter how often you bring the errors to their attention the BS continues. Dare to challenge their assertions and risk incurring their wrath.  Hey but 100k+ subscribers can't be wrong - or can they?  🙄

 

My advice for what it is worth, is to stick to text books for the basics so you can build an understanding of the concepts underpinning the subject, then armed with a good background on the subject it becomes significantly easier to sort the gurus from the BS artists. 👍

 

Cheers,

Alan R.

Hi Alan

Can you be specific, as the wet blanket approach,  is the only misinformation I am seeing here.

 

What actual errors have you found implementing a LT4320 ?  , or are you saying the manufacturers data sheet contains misinformation ?

Have you tried a LT4320 ? If not you will find the manufacturers data sheet extremely reliable. You will need though the DIP package device,the datasheet reveals essential information about careful choice of N channel mosfet devices.  https://www.analog.com/en/products/lt4320.html

 

Have you ever tried a jfet in a circuit ? What do you find erroneous or misinformation about

(noting it falls into your category of being a textbook )  Designing with Field effect transistor Siliconix Inc

 

Many forum members, are gaining insight into devices and ideas from the thread. Each topic has been achieved,  from personal experience and reliable data.  But its not only me - the thread is open to everyone to contribute.   Why not find a topic you are confident meets your criteria of information assisting audio reproduction, that you have personally tried,   and discuss it, ... as that is the idea.

 

If you have not yet found any devices that assist audio reproduction, then there is always opportunity to do so. 

 

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When amplifier manufacturers publish data about power amplifier or for that matter integrated amplifier power output, they in almost every case do so, by measuring the amplifier into a number of resistance loads, ie 4 ohm, 8 ohm 16 ohm as example, or provide a graph tabling each resistance. However we know few of us gain any pleasure from viewing  a resistor under load,  rather a loudspeaker is where we enjoy audio.

 

We would expect amplifiers to have graduated from the driving of resistance which most do extremely well, to the next classroom so to speak where they come face to face with the real requirements of a loudspeaker, we could say amplifiers are presently  at the kindergarten level 

 

A resistance load as we know from our earlier topic contains no reactance. If we examine actual loudspeaker reactance, we find a complex load, quite different.  Leading to asking what happens when a loudspeaker is attached to a amplifier, and is there any way of making the amplifier know about the loudspeaker,

 

This textbook is a valuable reference to explore some of these ideas,  should you wish to.    https://www.current-drive.info/9  

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On 22/02/2021 at 2:00 AM, stereo coffee said:

Hi Alan

Can you be specific, as the wet blanket approach,  is the only misinformation I am seeing here.

 

What actual errors have you found implementing a LT4320 ?  , or are you saying the manufacturers data sheet contains misinformation ?

Have you tried a LT4320 ? If not you will find the manufacturers data sheet extremely reliable. You will need though the DIP package device,the datasheet reveals essential information about careful choice of N channel mosfet devices.  https://www.analog.com/en/products/lt4320.html

 

Have you ever tried a jfet in a circuit ? What do you find erroneous or misinformation about

(noting it falls into your category of being a textbook )  Designing with Field effect transistor Siliconix Inc

 

Many forum members, are gaining insight into devices and ideas from the thread. Each topic has been achieved,  from personal experience and reliable data.  But its not only me - the thread is open to everyone to contribute.   Why not find a topic you are confident meets your criteria of information assisting audio reproduction, that you have personally tried,   and discuss it, ... as that is the idea.

 

If you have not yet found any devices that assist audio reproduction, then there is always opportunity to do so. 

 

 

My comment was a generic observation of the internet and not specifically aimed at anyone (I've yet to name) or about jfets.

 

Indeed I have used jfets in pre-amps and the front end of power amps as well as RF gear dating back to the 1970s so they are devices that I would like to think that I have some degree of familiarity with. :)

 

In many decades working in the industry I'm yet to find a datasheet or reference book from a semiconductor manufacturer with blatantly obvious technical data errors beyond the odd spelling or grammatical errors that somehow slipped through the proof reading process. 

 

However there are a few electronics YouTube channels that portray fiction as fact.  Like the one that is emphatic that no current flows through a zener diode once the zener or avalanche voltage has been reached or exceeded.  Same person can't explain Ohm's Law and doesn't know the difference between A, B and C taper potentiometers.  Just the other day he reviewed a digital multimeter and proclaimed that a 20% error in the reading was totally acceptable.  He went on to say "I like this meter so much I think I might stock it on my Amazon store......"  An opinion obviously, but even the novice hack weekend electronics hobbyist knows that a 20% error in the reading is way off the mark, especially when the product claims to be at least an order of magnitude better accuracy.

 

Unfortunately, pointing out the errors generally results in a blatant dismissal by him of the facts when quoting directly from the manufacturer's own specifications about his review results.  Either he's testing technique is wrong, the test bench standards of his reference units are faulty, the DMM he's reviewing is faulty or its performance specifications are highly over rated.  🙄   

 

Why my comments about the BS that surfaces on the internet?   Well consider the newbie electronics hobbyist with no prior training or study on the subject other than an interest to explore (let's say) the DIY electronics route.  Some don't ever question the BS until they let the magic smoke out or worse still they or someone else receives an electric shock, cause a fire or has a building burn down because of fundamental lack of understanding of the subject.

 

So just to make sure there are no misconceptions.  My comments are definitely not aimed at you. They are, as I stated previously on more than one occasion, applicable to some information available on the internet, therefore not everything you read, hear or see is always going to be 100% true.

 

As much as I would like to name the offenders, doing so in a world of litigation leaves anyone daring to do so open to financial ruin even if they are proven to be 100% true.  :(

 

Cheers,

Alan R.

 

 

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Hi Alan

There are indeed some obvious irregularities with information on you tube. The purpose of the thread is to narrow down idea's that benefit audio reproduction. George Ohm as you example either did not know,  or could explain negative resistance... yet it is there, and has staggering possibility. 

 

https://en.wikipedia.org/wiki/Negative_resistance

In electronics, negative resistance (NR) is a property of some electrical circuits and devices in which an increase in voltage across the device's terminals results in a decrease in electric current through it.[4][5]

This is in contrast to an ordinary resistor in which an increase of applied voltage causes a proportional increase in current due to Ohm's law, resulting in a positive resistance.[6] While a positive resistance consumes power from current passing through it, a negative resistance produces power.[7][8] Under certain conditions it can increase the power of an electrical signal, amplifying it.[

 

 

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On 19/02/2021 at 11:03 AM, stereo coffee said:

We can see if input sensitivity is too high- lets say 2 volts RMS we are never going to achieve the full output,

 

That depends on the output of the source.

 

My DAC outputs 0dBFS from a digital media as 2V RMS .... then it will achieve full amplifier swing.

 

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7 minutes ago, davewantsmoore said:

 

That depends on the output of the source.

 

My DAC outputs 0dBFS from a digital media as 2V RMS .... then it will achieve full amplifier swing.

 

Agreed ... but all that is there from the source,  for consumer equipment is only ...  316mv RMS line level. 

 

If you have CD with fairly steady output level,   then a multimeter can be used to very vaguely sense the millivolt output. If your meter can read RMS all the better. Measure  unloaded by any fixed resistance. The measurement should reconcile with the earlier audacity image, confirming the output as not 2V , but just consumer line level as 316mv RMS,  If lacking RMS ability your meter will jump to higher peaks, which similarly should follow the darker blue content of the earlier image.  Let us know what you find. 

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59 minutes ago, davewantsmoore said:

 

That depends on the output of the source.

 

My DAC outputs 0dBFS from a digital media as 2V RMS .... then it will achieve full amplifier swing.

 

 

So if my preamp, can output ~7v RMS and my amp requires 2.2V for full power, I'll have no problem driving the amp to its full output. Correct? 

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14 minutes ago, sir sanders zingmore said:

 

So if my preamp, can output ~7v RMS and my amp requires 2.2V for full power, I'll have no problem driving the amp to its full output. Correct? 

You would need to review schematics of your equipment,  to see if it is, or is not,   applying voltage gain to its line level input of x 22.15 , and assess if you wish to , what reactance, it is adding to achieve that increase in voltage.  If it is indeed increasing voltage x 22.15, then likely you will need attenuation to reduce level,  to correctly match to your amp.  If so, you should consult with your amplifier manufacturer.

 

 

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12 minutes ago, stereo coffee said:

You would need to review schematics of your equipment,  to see if it is, or is not,   applying voltage gain to its line level input of x 22.15 , and assess if you wish to , what reactance, it is adding to achieve that increase in voltage.  If it is indeed increasing voltage x 22.15, then likely you will need attenuation to reduce level,  to correctly match to your amp.  If so, you should consult with your amplifier manufacturer.

 

 

 

it has variable gain. Up to 18dB

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10 minutes ago, sir sanders zingmore said:

 

it has variable gain. Up to 18dB

In theory to match to 2.2V RMS sensitivity you will need to set the gain to 6.85db , a calculator here converts between all the values of db, dbM, V

https://www.analog.com/en/design-center/interactive-design-tools/dbconvert.html

 

To help,  the example shows  I have input line level as nominal  0.316v, with peak of 0.447v, to arrive at 6.85db. We can also see in the second image that the same values agree at 18db fairly closely as the manufacturers data of 7V,  being  7.943 V/V   

Screenshot from 2021-02-25 14-27-45.png

Screenshot from 2021-02-25 14-35-46.png

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1 hour ago, stereo coffee said:

In theory to match to 2.2V RMS sensitivity you will need to set the gain to 6.85db , a calculator here converts between all the values of db, dbM, V

https://www.analog.com/en/design-center/interactive-design-tools/dbconvert.html

 

To help,  the example shows  I have input line level as nominal  0.316v, with peak of 0.447v, to arrive at 6.85db. We can also see in the second image that the same values agree at 18db fairly closely as the manufacturers data of 7V,  being  7.943 V/V   

Screenshot from 2021-02-25 14-27-45.png

Screenshot from 2021-02-25 14-35-46.png

 

The default is 8dB so probably close enough

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7 hours ago, sir sanders zingmore said:

So if my preamp, can output ~7v RMS and my amp requires 2.2V for full power, I'll have no problem driving the amp to its full output. Correct? 

 

Yes, you could drive the amp to well beyond full power.

 

That being said, your preamp is perhaps an example of the "reactance" being placed in between the music and the power amplifier.

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1 hour ago, davewantsmoore said:

 

Yes, you could drive the amp to well beyond full power.

 

That being said, your preamp is perhaps an example of the "reactance" being placed in between the music and the power amplifier.

I’m not sure what “reactance” is and whether it is bad or good. 
I do know that my preamp sounds very good to me (a lot better than a many others I’ve heard - including the one that shall not be mentioned 😀)

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18 minutes ago, sir sanders zingmore said:

I’m not sure what “reactance” is and whether it is bad or good. 

 

I know what it should be, but this thread...

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16 hours ago, sir sanders zingmore said:

I’m not sure what “reactance” is and whether it is bad or good. 
I do know that my preamp sounds very good to me (a lot better than a many others I’ve heard - including the one that shall not be mentioned 😀)

It's neither bad nor good, it just is. You can't build any AC or signal equipment that doesn't have it..

 

https://whatis.techtarget.com/definition/reactance

 

Put simply, it's just the non resistive components of impedance in an AC circuit.

impedance.gif.d710c592f569a5ed191d8b7f61764b71.gif

Z - Impedance

R - Resistance

XL - Inductive Reactance

Xc - Capacative Reactance

Edited by bob_m_54
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1 minute ago, bob_m_54 said:

It's neither bad nor good, it just is. You can't build any AC or signal equipment that doesn't have it..

 

https://whatis.techtarget.com/definition/reactance

 

Your phono cartridge has it, so do your crossovers and speakers, and everything else in between.  I have been watching this term being bandied about, and I really thought they were talking about some other new thing that happened to have the same name.   Either that or I had stumbled into some parallel universe :) 

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11 minutes ago, aussievintage said:

 

Your phono cartridge has it, so do your crossovers and speakers, and everything else in between.  I have been watching this term being bandied about, and I really thought they were talking about some other new thing that happened to have the same name.   Either that or I had stumbled into some parallel universe :) 

Yeah, I don't understand how people take up a term, then sort of convolute it to mean something it just isn't. Unless someone has invented a new "Reactance" since I learned about it over 48 years ago.

 

Edit: you can eliminate reactance completely... just leave your gear switched off :)

Edited by bob_m_54
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8 minutes ago, bob_m_54 said:

It's neither bad nor good, it just is. You can't build any AC or signal equipment that doesn't have it..

 

https://whatis.techtarget.com/definition/reactance

 

Put simply, it's just the non resistive components of impedance in an AC circuit.

impedance.gif.d710c592f569a5ed191d8b7f61764b71.gif

 

Therefore if we want nothing that adds to create reactance, in- between our source and power amp,  resistance we know is free of reactance, suggests as being ideal.   The form this takes is known as impedance bridging:   https://en.wikipedia.org/wiki/Impedance_bridging

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4 minutes ago, stereo coffee said:

Therefore if we want nothing that adds to create reactance,

 

Things don't create reactance, they HAVE reactance.  

 

5 minutes ago, stereo coffee said:

resistance we know is free of reactance, suggests as being ideal.  

 

 

Suggests?

 

6 minutes ago, stereo coffee said:

The form this takes is known as impedance bridging:   https://en.wikipedia.org/wiki/Impedance_bridging

 

Is this where you got this idea - where it says  "assuming all impedances are purely real"    ?  You know that's just a simplification for illustrative purposes?

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