Bob, I'm glad to see you measuring connectors and relays.
As you know, relays are practical, but a potential problem, especially if you are trying to achieve a new record in low distortion design.
Banana plugs are problematic and we use American made (or at least engineered) banana plugs on the outputs of the JC-1 power amp for just this reason. The factory complained that the plugs we specified were too expensive and not as attractive as their Chinese counterparts, but we knew better, just from listening experience. Your measurements tend to confirm this.
As you know, relays are practical, but a potential problem, especially if you are trying to achieve a new record in low distortion design.
Banana plugs are problematic and we use American made (or at least engineered) banana plugs on the outputs of the JC-1 power amp for just this reason. The factory complained that the plugs we specified were too expensive and not as attractive as their Chinese counterparts, but we knew better, just from listening experience. Your measurements tend to confirm this.
Bob said:
"Interestingly, the banana plugs showed more second harmonic than third, and the ordinary plug combination was slightly better than the expensive one in this regard. The third row of the data represents the readings produced by the setup itself, when the pigtails going to the plug combination are merely tightly twisted together. Both plug combinations show a connector resistance of about 13 milliohms. All working distortion spectra lie between -142 dB (0.000004%) and -135 dB (0.000016%). These are very encouraging numbers, but they are based on a very small sample. Both sets of connectors were brand new."
Really? You must have been reading an entirely different thread then.
Jan Didden
"Interestingly, the banana plugs showed more second harmonic than third, and the ordinary plug combination was slightly better than the expensive one in this regard. The third row of the data represents the readings produced by the setup itself, when the pigtails going to the plug combination are merely tightly twisted together. Both plug combinations show a connector resistance of about 13 milliohms. All working distortion spectra lie between -142 dB (0.000004%) and -135 dB (0.000016%). These are very encouraging numbers, but they are based on a very small sample. Both sets of connectors were brand new."
john curl said:
Really? You must have been reading an entirely different thread then.
Jan Didden
john curl said:
Bob says the cheap stuff was slightly BETTER than the expensive stuff.
Bob says even the worst stuff is better than -135dB.
You say that confirms your listening tests that expensive sounds better.
I resent being mislead by you in this way. I resent you treating me as a dummy that cannot read plain English and that is too stupid to think for himself.
Jan Didden
john curl said:
Well, brains may sometimes go a longer way than money. To each his own.
Regards,
Milan
Bob made a FEW measurements. I have NOT measured my dual banana connectors, but we have found from listening experience that they sound better than cheaper connecters that look prettier: (gold, bright colors, etc), but also more easily strip and usually have some steel in the connector assembly somewhere. We KNOW that the connectors that we use were originally designed for American military-industrial applications, but they are sort of 'old fashioned' looking.
About 20 years ago, Dave Wilson independently found these connectors to be superior, and my WATT 1 loudspeakers use this connector. He has changed connectors over the years, BUT that could be for cosmetic or IEC regulations. My banana connectors would not meet IEC specs as they are written today.
I did misread what Bob Cordell posted. I took the eq residual for the 'expensive' connector. However, I would agree that many expensive connectors could measure badly, but I don't think that the connector he measured is the 'expensive' connector that I use.
About 20 years ago, Dave Wilson independently found these connectors to be superior, and my WATT 1 loudspeakers use this connector. He has changed connectors over the years, BUT that could be for cosmetic or IEC regulations. My banana connectors would not meet IEC specs as they are written today.
I did misread what Bob Cordell posted. I took the eq residual for the 'expensive' connector. However, I would agree that many expensive connectors could measure badly, but I don't think that the connector he measured is the 'expensive' connector that I use.
john curl said:
John, I tend to agree with you. I did not intend my very limited sample to justify the use of cheap connectors. Let's face it, my ordnary connectors may have been quite good. Also, the connectors I used were brand new and newly seated. My results thus did not allow for effects of aging and oxidation. My results were encouraging, but certainly not license for use of cheap connectors. I have always belived that the most important aspect of high-priced cables and interconnects was the quality and reliability of the connectors. I have often wondered if, when people change cables and get an improvement in sonics, if much of it just has to do with the related re-seating process that tends to self-clean the contacts.
Bob
FM Acoustics uses banana plug that looks like for welding usage. The head is the size of index finger, and the cables are 4AWG.
Many amps just use Neutrik connectors.
Many amps just use Neutrik connectors.
john curl said:
John,
I knew that. I fully expected it. I know you were not conciously trying to actively mislead us. I made that strong statement (for which I post hoc apologize) as the best way to make you think about this, to realise how biased we ALL are, how vulnerable we ALL are. We as humans are perfectly capably to read 'black' and then state we read 'white', in all honesty, because 'white' happens to fit our bias and belief system.
That is why the only reliable and 'honest' listening tests are controlled blind testst where the influence of bias is diminished to the greatest extend possible.
Because we are, as humans, perfectly capable to hear 'black' and then, in all honesty, state we just heard 'white'.
Have a nice day,
Jan Didden
Asymmetry in the output stage
Hi all,
I was reading this interesting thread and I wanted to ask Bob and John a question regarding asymmetry in the output stage due to thermal effects.
This question came up as I was reading the website of Jim Lesurf. On this site he discusses that many musical waveforms are asymmetric
http://www.st-and.demon.co.uk/AudioMisc/asymmetry/asym.html
In another article by him he discusses the output stage of a Class AB amplifier and this goes directly to what Bob stated was for him the worst distortion...those occurring from crossover distortion.
Here he discusses a thermal model for how an output stage can be made asymmetric due to thermal effects from asymmetric waveforms heating the positive and negative halves of the complementary output stage unevenly (see page 3). He also discusses distortion measurement techniques and their relevance to what we hear (page 1) and his theory that some of the distortion that is audible is not measured by current tests and may be due to an asymmetric output stage (Page 2).
http://www.st-and.demon.co.uk/AudioMisc/distortion/page1.html
http://www.st-and.demon.co.uk/AudioMisc/distortion/page2.html
http://www.st-and.demon.co.uk/AudioMisc/distortion/page3.html
What, if any, relevance do you think Mr. Lesurf's ideas hold? If this is a relevant form of distortion it seems to fall, more or less, as a form of crossover distortion that would only show up with real music or at least a test with asymmetric waveforms should be devised to see if it has merit. As a form of crossover distortion it seems that it would be difficult to address with negative feedback. Would one type of transistor be less susceptible than another (MOSFET vs. BJT?)
Thanks for your input.
Hi all,
I was reading this interesting thread and I wanted to ask Bob and John a question regarding asymmetry in the output stage due to thermal effects.
This question came up as I was reading the website of Jim Lesurf. On this site he discusses that many musical waveforms are asymmetric
http://www.st-and.demon.co.uk/AudioMisc/asymmetry/asym.html
In another article by him he discusses the output stage of a Class AB amplifier and this goes directly to what Bob stated was for him the worst distortion...those occurring from crossover distortion.
Here he discusses a thermal model for how an output stage can be made asymmetric due to thermal effects from asymmetric waveforms heating the positive and negative halves of the complementary output stage unevenly (see page 3). He also discusses distortion measurement techniques and their relevance to what we hear (page 1) and his theory that some of the distortion that is audible is not measured by current tests and may be due to an asymmetric output stage (Page 2).
http://www.st-and.demon.co.uk/AudioMisc/distortion/page1.html
http://www.st-and.demon.co.uk/AudioMisc/distortion/page2.html
http://www.st-and.demon.co.uk/AudioMisc/distortion/page3.html
What, if any, relevance do you think Mr. Lesurf's ideas hold? If this is a relevant form of distortion it seems to fall, more or less, as a form of crossover distortion that would only show up with real music or at least a test with asymmetric waveforms should be devised to see if it has merit. As a form of crossover distortion it seems that it would be difficult to address with negative feedback. Would one type of transistor be less susceptible than another (MOSFET vs. BJT?)
Thanks for your input.
Re: Re: Re: Relay Distortion
Automotive relays usually have very strong electromagnet and massive pure copper contacts - that could be the reasons for good results.
Bob Cordell said:
Automotive relays usually have very strong electromagnet and massive pure copper contacts - that could be the reasons for good results.
Hi,
I have seen silver used in the few I have taken apart.
and probably have a strong wiping action to re-clean them due to the hostile environment they operate in.
I have seen silver used in the few I have taken apart.
A lot of cars and trucks use Bosch/Bosch-style relays, the Bosch relays have a silverplated contact.
Back in ancient times, a couple of diy amp designs were published here with PCBs that were layed out to use the familiar square block Bosch SPST car output relay.
Best automotive relay i've tried is a wallmount Bosch SPST relay for big trucks, a 2-contact type rated at 100 amps.(Bosch part serial on file somewhere, using them in my truck because of the high bias multi-channel power amps it has installed)
Jan,
i don't need a relay for the purpose of loudspeaker protection, mine have built-in protection for dc and overload, the relays are for the amp.
trivial fun and games: In 1987, Display electronics overhere quoted me DFL50.-/each for the SDS-S4 relay + minimum order of 5.
Quite anxious to hear from Mr Curl what the make is of the United Fruit Connectors he flavors.
Back in ancient times, a couple of diy amp designs were published here with PCBs that were layed out to use the familiar square block Bosch SPST car output relay.
Best automotive relay i've tried is a wallmount Bosch SPST relay for big trucks, a 2-contact type rated at 100 amps.(Bosch part serial on file somewhere, using them in my truck because of the high bias multi-channel power amps it has installed)
Jan,
i don't need a relay for the purpose of loudspeaker protection, mine have built-in protection for dc and overload, the relays are for the amp.
trivial fun and games: In 1987, Display electronics overhere quoted me DFL50.-/each for the SDS-S4 relay + minimum order of 5.
Quite anxious to hear from Mr Curl what the make is of the United Fruit Connectors he flavors.
jacco vermeulen said:
Jacco I specifically asked because I was interested in the timing requirements you mentioned, that's all.
Jan Didden