Not really. This isn't new ground, some transmitters as far back as the Seventies applied ugly modulation schemes (essentially PWM) to the sine carrier and relied on internal losses and the output network to filter out of band components and meet regulatory requirements. Audio occupies three decades of bandwidth, an FM radio station 0.001 (?) decade. It's an example to illustrate why the typical rectification junk that bad connectors could impose on audio frequencies has little mapping to their effect in the RF band. Even that's assuming analogue transmission, an increasingly dead art. They're not comparable.
Well John, some people feel they have little or nothing to learn from somebody's experience; I don't expect you to understand their all pervading knowledge, but by now, I'm pretty sure you've stopped pitying them a long time ago.
How and on what basis people choose to believe they know as much as, or even more than seasoned pros, I never did and most probably never will understand, that is clearly beyond my grasp.
The acid test for many such undiscovered giants is simple and painful: show us what you made. Don't dally over what I did, go ahead and do better. Don't keep proposing and philosophising, DO it better if you think you can. And, I believe it is a time honored American saying: if you're so smart, why aren't you rich? Or at least well known in the audio community?
I profited from your message regarding higher harmonics. It never occured to me to go beyond 7th as long as the decay was the way I like it. My own equipment will reliably do as high up as 100 kHz (the point where my tone generator No.1 hits the nominal 0.001%, obviously it will do more but quickly becomes unreliable). If I'm happy with 0.05%, I can use generator No.2 to go as high as 50 MHz.
Now that you released the bug, it gnaw at me until I try it.
I admit it, I am now very curios, I've been served thought food.
I was thinking of receivers, as I said. They are directly comparable. Transmitters have much smaller dynamic ranges, so I'm not sure why you introduced them into the discussion.rdf said:
Perhaps this would be a good time to remind everyone that the essential difference between an amateur and professional is how much they charge for their goods/services. Competence is a separate issue. I continue to be astonished at the elementary mistakes found in some commercial audio circuits. There is very little correlation between price and real quality (apart, perhaps, from the thickness of the metalwork).dvv said:
Actually, its not just in audio that people get well paid for being incompetent: banking is another industry with similar problems.
There's a nice crack between those 2 states where the gremlins can grow and multiply: define and distinguish precisely, "less than perfect" vs. "bad" ...
Since experiments appear to be key, and I recall SY is partial to phono amps, consider this. We get his latest design, and assemble 2 lots of parts necessary to make. One is constructed in the correct, normal manner, and for the second, every link between a lead of one component and another has an average quality, consumer grade RCA plug simply pushed into a socket inserted into it, forming part of the connection. Then, to make it even more interesting put the circuits aside for a year in a normal domestic environment, unused -- finally, without touching anything on the 2 assemblies, set up a listening test environment, and AB the two versions ...
Simply, the vast majority of RF systems are extremely narrow band devices compared to an audio system and receivers match transmitters. The issues related to connectors are broad band. Audio systems compared to RF systems are extremely broadband, as is our hearing. More of the potential impact of lousy connectors will fall in the band of interest in an audio system than in any RF system I know. Drawing parallels is pointless.
but the thing is, these pronounced 7th harmonic and higher, what exactly produces them? John has consistently claimed opamps do, yet opc's 'the wire' amps have what is effectively an opamp (LME49830) driving lateral semelab fets with 400ma bias and result in predominantly 2H at -110dB and falling harmonics, 3H @ ~ -117dB, 4H -130dB, 5H -132dB, 6H -130dB, 7H -132dB, 8H -135dB, 9H, -130dB, 10H -132dB so where is this buggaboo? thats when driven by a high end (regulated) switchmode power supply as well... oh the horror!
I have another amp of his, the LPUHP that is ALL opamps... 11 of them a channel with an instrumentation amp FE and 8 parallel buffers for output and it turned out 2H at -128dB, 3H @ ~ -120dB, 4H -136dB, 5H -128dB, 6H -130dB, 7H -129dB, 8H (appears completely off the bottom of the scale), 9H -137dB, 10H -138dB
both amps have balanced input, so even harmonics are lower.
there is plenty more measurements (taken with new top of the line AP) of other parameters, but this is the one under discussion, not an attempt to say THD is everything
Where are the evil distortions? nobody doubts Johns experience and knowledge (in some areas, discrete poweramps and preamps most notably), well I would hope not, but its claims like these that in reality have little substance, that tend to cast some doubt over some of his very public opinions.
this 7H thing keeps being brought up quite regularly, but when info to the contrary is posted (I have done this before) its not absorbed, or is ignored and 7H brought up again some other time. I wonder just how much testing really resulted in these generalisations and how long ago...
it seems to me that untoward distortions of higher order can be created with uncaring design of all types and reduced with care.
I have another amp of his, the LPUHP that is ALL opamps... 11 of them a channel with an instrumentation amp FE and 8 parallel buffers for output and it turned out 2H at -128dB, 3H @ ~ -120dB, 4H -136dB, 5H -128dB, 6H -130dB, 7H -129dB, 8H (appears completely off the bottom of the scale), 9H -137dB, 10H -138dB
both amps have balanced input, so even harmonics are lower.
there is plenty more measurements (taken with new top of the line AP) of other parameters, but this is the one under discussion, not an attempt to say THD is everything
Where are the evil distortions? nobody doubts Johns experience and knowledge (in some areas, discrete poweramps and preamps most notably), well I would hope not, but its claims like these that in reality have little substance, that tend to cast some doubt over some of his very public opinions.
this 7H thing keeps being brought up quite regularly, but when info to the contrary is posted (I have done this before) its not absorbed, or is ignored and 7H brought up again some other time. I wonder just how much testing really resulted in these generalisations and how long ago...
it seems to me that untoward distortions of higher order can be created with uncaring design of all types and reduced with care.
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Exactly the same here.
My curiosity was aroused by Accuphase and their Damping Factor switch as found on their 201 integrated amp from circa 1975. Admittedly, it was hardly scientific, I just tried the approximate values they used. Also, I tried it on just my speakers only, AR94, meaning it's possible it might have worked better with other speakers.
In the end, I very clearly preferred the topmost setting of nominally 66:1/8 Ohms.
I do not believe that changing the DF was the ONLY thing Bob did, perhaps a part of what he did. But I feel there must have been more, but he's not telling.
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As I said, read about third-order IM. You appear to be unaware of this.rdf said:
That might be an interesting test, but it adds rather too many complications:fas42 said:
1. lots of extra stray capacitance
2. RCAs used in situations quite unlike their normal use (feeding a voltage into a high impedance input is not sensitive to minor contact problems - feeding a current into a low impedance circuit node could be)
3. leaving the contacts untouched for a year might mimic normal domestic practice, but not known best practice
Let's assume this test showed an audible difference. It tells us almost nothing about normal RCA audio use.
Connections have a sound ?
All I will say is very often cheapest is the best . Naim used BNC for inputs . I doubt that any Audiophile connector got close to how well they work . DIN also if of the Preh type . XLR is wonderful .
I use carbon film resistors a lot . I love the cost , music to my ears . If the measurement is OK they do not get changed . I do have a small belief they are nicer ? Less than $1 / 100 ( 55 pence ) . Main reason I use them is I can keep a stock of most values very cheaply . 95% of the time they are fine . The metal films might subtly work better . However the hiss they have is not as nice . Foil types are excellent , cost is too high . I doubt if any high end amplifier would have carbon film even if it did sound better ? For MC inputs I use 2 x BC MRS 25 coupled together in inductive anti phase . Whilst I can not prove it works it seems to be almost logical . A radio amateurs book suggested it it trying to get the last bean out of a design . Dvv that seems almost your sort of thing ( capacitor groups for better HF ) . To hell what people here think where is the harm in a few pennies spent ? Complexity for once with virtue ?
All I will say is very often cheapest is the best . Naim used BNC for inputs . I doubt that any Audiophile connector got close to how well they work . DIN also if of the Preh type . XLR is wonderful .
I use carbon film resistors a lot . I love the cost , music to my ears . If the measurement is OK they do not get changed . I do have a small belief they are nicer ? Less than $1 / 100 ( 55 pence ) . Main reason I use them is I can keep a stock of most values very cheaply . 95% of the time they are fine . The metal films might subtly work better . However the hiss they have is not as nice . Foil types are excellent , cost is too high . I doubt if any high end amplifier would have carbon film even if it did sound better ? For MC inputs I use 2 x BC MRS 25 coupled together in inductive anti phase . Whilst I can not prove it works it seems to be almost logical . A radio amateurs book suggested it it trying to get the last bean out of a design . Dvv that seems almost your sort of thing ( capacitor groups for better HF ) . To hell what people here think where is the harm in a few pennies spent ? Complexity for once with virtue ?
Yes they do, I see PIM problems all the time in telecommunications. Ferrous materials in connectors cause trouble and so does the audiophile favourite silver
You can bet your Courage Light Ale on it, Nige.
I believe there are two distinct possibilities for that.
The first and most obvious is the quality of the RCA Cinch plugs. I refer to both metal contact quality, metal materials, whether it's gold plated or not, how well do can they be screwed on, etc.
Less obvious but still present is something you can try yourself at home. Once a year, do use some cotton swabs and medicinal alcohol to clean both the male and female ends - do not be surprised at what you might see. And the difference just may be audible, obviously no revelation, but just tha n-th little bit.
This obviously also depends on where you live and how clean is the air at your home, and before slamming this, do remember than not everybody lives in countries with an aggressive environmental control.
High Dvv . I as everyone use RCA . I like the very cheap Neutrik ones , the very expensive ones they make I strongly dislike . These as my friend John will tell you are needed where pro-Audio is forced to use unbalanced RCA connectors . They brake ground and hot simultaneously which is important if using 1000's of watts when someone might trip over a cable . John admits he doesn't like them .
All my test gear uses BNC . I often think I should rip out my RCA and use only BNC .
Although unlikely to be of great importance one hi fi magazine stated RCA to have a typical impedance of 230 R ( no idea if true ) . It was suggested that the cables would often be 50 or 75 R especially in early days . Like my previous idea of anti-phase induction in spiral cut resistors I can see no reason why using matched connectors and cable would be stupid .
Max Townsend sold 300 ohm ribbon cable with RCA's . These were said to work well . Maybe something was working to advantage here ? More surprisingly often shielding is not absolutely necessary . MC pick-up's don't always need screened lead out wires ! Some take the wires to a preamp close to the pick up .
There are chemical solutions which promote better connection between metals . I would prefer to use BNC .
Gold Plated Phono Plugs
Profi professional phono plug
All my test gear uses BNC . I often think I should rip out my RCA and use only BNC .
Although unlikely to be of great importance one hi fi magazine stated RCA to have a typical impedance of 230 R ( no idea if true ) . It was suggested that the cables would often be 50 or 75 R especially in early days . Like my previous idea of anti-phase induction in spiral cut resistors I can see no reason why using matched connectors and cable would be stupid .
Max Townsend sold 300 ohm ribbon cable with RCA's . These were said to work well . Maybe something was working to advantage here ? More surprisingly often shielding is not absolutely necessary . MC pick-up's don't always need screened lead out wires ! Some take the wires to a preamp close to the pick up .
There are chemical solutions which promote better connection between metals . I would prefer to use BNC .
Gold Plated Phono Plugs
Profi professional phono plug
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