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#41
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Crosstalk in snake cable that include speaker cables and miccables
On 6/7/2018 11:45 PM, geoff wrote:
iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. I had a chat with the Studio Six guys at Infocomm yesterday and asked if they were doing anything on Android yet. Nope, they said (as everyone said years ago) that Androids are different enough so that they can't be sure their software will run on the version that the user has. Same with AudioControl, who made a really good SPL meter that works on my ZTE Android 4.0 phone, but when I got a new phone last year because all of my apps were telling me to upgrade - to versions that wouldn't run on Version 4 - it wouldn't work. They've abandoned it, similarly, because it's too difficult to reliably program for Android. So I use my antique Radio Shack analog SPL meter and avoid buying a $700 iPhone. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#42
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Crosstalk in snake cable that include speaker cables and miccables
On 9/06/2018 12:22 AM, Mike Rivers wrote:
On 6/7/2018 11:45 PM, geoff wrote: iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. I had a chat with the Studio Six guys at Infocomm yesterday and asked if they were doing anything on Android yet. Nope, they said (as everyone said years ago) that Androids are different enough so that they can't be sure their software will run on the version that the user has. Same with AudioControl, who made a really good SPL meter that works on my ZTE Android 4.0 phone, but when I got a new phone last year because all of my apps were telling me to upgrade - to versions that wouldn't run on Version 4 - it wouldn't work. They've abandoned it, similarly, because it's too difficult to reliably program for Android. So I use my antique Radio Shack analog SPL meter and avoid buying a $700 iPhone. Well I have found that there is an Android equivalent (or better) of anything on iPhone now. And luckily have not have had the update probs you've encountered. geoff |
#43
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Crosstalk in snake cable that include speaker cables and mic cables
On Fri, 8 Jun 2018 00:24:16 -0000 (UTC), david gourley
wrote: (Scott Dorsey) said...news david gourley wrote: Trevor said...news On 7/06/2018 1:05 AM, Scott Dorsey wrote: In article , Tim Sprout wrote: On 6/5/2018 6:24 AM, wrote: I can confirm that this type snake CAN create an ultrasonic oscillation that can quickly damage a power amp. How does one detect ultrasonic oscillations? Usually by the smoke. I once saw a Phase Linear amp shoot fire three feet in the air due to stability issues. It was very impressive but cut the band's act somewhat short. They weren't nick-named "Flame Linear's" for nothing. :-) The SAEs didn't seem to be far behind, either. Agreed, and SWTPC also was famous for instability. The Phase Linear, though, was famous because it just had such an enormous amount of power and such poor stability margins. The combination was bad. --scott Yessir, those Tigers could roar ! david --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus Those darn things would break into spurious oscillation driving a resistive load. I came up with a mod that made them stable enough that a local rock band used them as their main amps. |
#44
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Crosstalk in snake cable that include speaker cables and miccables
On 8/06/2018 12:12 PM, Mike Rivers wrote:
On 6/7/2018 9:47 PM, geoff wrote: My multimeter collection, HF responses starting to drop at: Fluke 114Â*Â*Â* 4.5kHz Fluke 17B+Â*Â*Â* 2.5kHz Dick Smith (OEM ?)Â*Â*Â* 10kHz That's pretty good. My Fluke 77 goes up to about 2 kHz if I recall correctly. I'm not near it at the moment. Fluke 8050A benchtopÂ*Â*Â* 20kHz(+?), which is as high as my iPod Touch with SignalSuite goes ... The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. But any decent computer-audio adapter that does 24/192 makes a great device for measuring audio signals, oscilloscope, spectrum analyser etc. to well above the audio band. Far better at low frequencies than nearly all CRO's and spectrum analysers that do HF. Trevor. |
#45
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Crosstalk in snake cable that include speaker cables and miccables
On 8/06/2018 4:45 PM, geoff wrote:
On 8/06/2018 2:12 PM, Mike Rivers wrote: The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. How do you run those on an iPod? Trevor. |
#46
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Crosstalk in snake cable that include speaker cables and miccables
On 8/06/2018 10:22 PM, Mike Rivers wrote:
On 6/7/2018 11:45 PM, geoff wrote: iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. I had a chat with the Studio Six guys at Infocomm yesterday and asked if they were doing anything on Android yet. Nope, they said (as everyone said years ago) that Androids are different enough so that they can't be sure their software will run on the version that the user has. Same with AudioControl, who made a really good SPL meter that works on my ZTE Android 4.0 phone, but when I got a new phone last year because all of my apps were telling me to upgrade - to versions that wouldn't run on Version 4 - it wouldn't work. They've abandoned it, similarly, because it's too difficult to reliably program for Android. So I use my antique Radio Shack analog SPL meter and avoid buying a $700 iPhone. Since it is difficult/expensive to calibrate either, you are probably just as well off using your ears and making a guess. Trevor. |
#47
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Crosstalk in snake cable that include speaker cables and miccables
On 9/06/2018 4:21 PM, Trevor wrote:
On 8/06/2018 4:45 PM, geoff wrote: On 8/06/2018 2:12 PM, Mike Rivers wrote: The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. How do you run those on an iPod? Trevor. SignalSuite and Guitar Toolbox were IOS apps, not Android, which was barely around (in the smartphone 'app' department at least) in those days anyway. Now there are Android equivalents. geoff |
#48
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Crosstalk in snake cable that include speaker cables and miccables
On 9/06/2018 3:08 PM, geoff wrote:
On 9/06/2018 4:21 PM, Trevor wrote: On 8/06/2018 4:45 PM, geoff wrote: On 8/06/2018 2:12 PM, Mike Rivers wrote: The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. How do you run those on an iPod? SignalSuite and Guitar Toolbox were IOS apps, not Android, which was barely around (in the smartphone 'app' department at least) in those days anyway. Didn't know iPods ran IOS apps? Don't you need an iPad or iPhone? Trevor. |
#49
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Crosstalk in snake cable that include speaker cables and miccables
On 9/06/2018 6:35 PM, Trevor wrote:
On 9/06/2018 3:08 PM, geoff wrote: On 9/06/2018 4:21 PM, Trevor wrote: On 8/06/2018 4:45 PM, geoff wrote: On 8/06/2018 2:12 PM, Mike Rivers wrote: The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. iPOD.Â* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.Â* Android didn't do that back then. How do you run those on an iPod? SignalSuite and Guitar Toolbox were IOS apps, not Android, which was barely around (in the smartphone 'app' department at least) in those days anyway. Didn't know iPods ran IOS apps? Don't you need an iPad or iPhone? Trevor. Whatever..... Whatever it was, it was proprietary. geoff |
#50
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Crosstalk in snake cable that include speaker cables and miccables
On 6/8/2018 9:25 PM, Trevor wrote:
Since it is difficult/expensive to calibrate either, you are probably just as well off using your ears and making a guess. It's difficult to calibrate to the standards required by the Music Police for writing tickets, but with a loudspeaker, pink noise source, and a hardware SPL meter (all of which I have) you can make a rough calibration that will be good enough to let you know, after listening all day and your ears are getting dull, if things are getting too loud. The AudioControl app (that doesn't work on my present phone) tracked my calibrated SPL meter quite well. I can calibrate any of the other SPL phone apps at a single point and they're repeatable at that SPL, but because the AGC isn't disabled, lower levels are boosted and higher levels are sat on before they get to the meter app, so everything comes out at about the same reading. The Kewelsoft SPL meter app allows you to calibrate it at three points and it creates a calibration curve, but that doesn't help in this situation. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#51
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Android Audio Test Apps (Was: Crosstalk in snake cable that includespeaker cables and mic cables)
On 6/8/2018 11:35 PM, Trevor wrote:
SignalSuite and Guitar Toolbox were IOS apps, not Android, which was barely around (in the smartphone 'app' department at least) in those days anyway. Didn't know iPods ran IOS apps? Don't you need an iPad or iPhone? Signal Suite is an audio signal generator. For Android (and maybe iOS) the Keuwlsoft Dual Channel Function Generator app is very flexible and works on all of my Android devices. It's a little tricky to get the hang of how the signals are assigned to the left and right outputs, but no worse than a digital mixing console. Of course the problem with using your phone as a signal generator is that all you have for an output is a phone jack (or virtual one) and you can't drive an input to +24 dBu with that if you want to find out how much headroom the equipment or system you're testing has. Most line level inputs have enough sensitivity so that you can run a frequency response check or put noise into a room to look for problem spots, so it, with the proper test leads, can be a handy tool for field work. The input side, though, is a different story. If you want to measure actual signal level, you need to disable the AGC (and also you need to calibrate it). -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#52
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Crosstalk in snake cable that include speaker cables andmic cables
geoff wrote:
On 9/06/2018 6:35 PM, Trevor wrote: On 9/06/2018 3:08 PM, geoff wrote: On 9/06/2018 4:21 PM, Trevor wrote: On 8/06/2018 4:45 PM, geoff wrote: On 8/06/2018 2:12 PM, Mike Rivers wrote: The iPad is limited to 20 kHz or so due to the fact that it's going through an A/D converter running at a sample rate of 44.1 or maybe 48 kHz. iPOD.* Yeah. Only Apple product I own - got it especially for SignalSuite and Guitar Toolbax.* Android didn't do that back then. How do you run those on an iPod? SignalSuite and Guitar Toolbox were IOS apps, not Android, which was barely around (in the smartphone 'app' department at least) in those days anyway. Didn't know iPods ran IOS apps? Don't you need an iPad or iPhone? Trevor. Whatever..... Whatever it was, it was proprietary. geoff The iPod touch is an iPhone without the phone bits. It runs iOS. |
#53
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Crosstalk in snake cable that include speaker cables and mic cables
Mike Rivers wrote:
geoff wrote: My multimeter collection, HF responses starting to drop at: Fluke 114Â*Â*Â* 4.5kHz Fluke 17B+Â*Â*Â* 2.5kHz Dick Smith (OEM ?)Â*Â*Â* 10kHz That's pretty good. My Fluke 77 goes up to about 2 kHz if I recall correctly. I'm not near it at the moment. ** To me it seems strange that instruments intended for engineers and service techs to use for all kinds of electronic work have such poor AC response.. Most analogue multimeters cover at least the audio band and beyond, so if you can hear a sound coming from a loudspeaker, the meter will measure the signal level for you. It can substitute for a VU meter if need be and test line voltage PA installations. In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html Typical specs we 11Mohms input impedance on DC volts. 1.5 V to 1500V AC or DC in 7 ranges. 3 to 5 MHz bandwidth on AC readings. 100 ohms to 1000 Mohms FSD in 7 ranges. 10 ohms at centre on lowest ohms range with 100mA of SC current. (enough to make a loud click in a speaker and/or see which way the cone moves). BTW: Ever try to test the resistance of a speaker in a noisy room with a DMM ?? ..... Phil |
#54
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Crosstalk in snake cable that include speaker cables and miccables
On 6/9/2018 6:29 PM, Phil Allison wrote:
** To me it seems strange that instruments intended for engineers and service techs to use for all kinds of electronic work have such poor AC response. I'm sure that there are still laboratory-grade digital multimeters that cover the audio band, but for service applications, mostly of your AC measurement requirements aren't for loudspeaker power, but for line power, and maybe to check out a (line frequency) transformer. I have an H-P 400D and 4300 analog voltmeters for audio measurements. Their scales are logarithmic, in dB, cover from millivolts to shocking volts. I paid less than $25 for each of those and have had them for years. I also have an NTI Minilyzer that's digital but I think its maximum input level is +18 dBu, so if I want to check out a devices with a specified maximum output level of more than that, I have to go the analog route. And the Digilizer cost a few hundred bucks. Most analogue multimeters cover at least the audio band and beyond, so if you can hear a sound coming from a loudspeaker, the meter will measure the signal True, but a decent one is more expensive than a digital multimeter, and a cheap one may not make as accurate measurements. Depends on what you need and why you're making the measurement. I wrote an article in Recording magazine about multimeters and making audio level measurements, and the bottom line was that you could use a budget priced meter to calibrate the audio interface for your computer (that you probably already have) at a frequency that you can rely on the meter to measure accurately, then use your interface as a "meter" to measure over the full audio range. In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. For my article, I was reluctant to suggest buying a 50 year old analog meter that could handle the full audio range, for fear that I'd soon have to write an article about repairing antique test equipment. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#55
Posted to rec.audio.pro
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Crosstalk in snake cable that include speaker cables and miccables
On 10/06/2018 12:48 PM, Mike Rivers wrote:
On 6/9/2018 6:29 PM, Phil Allison wrote: In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. The AVO meters were the most common in places I worked. Still have my AVO model 8. If you don't fry them, no reason they won't outlast the user. Trevor. |
#56
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Crosstalk in snake cable that include speaker cables and mic cables
Mike Rivers wrote:
Phil Allison wrote: ** To me it seems strange that instruments intended for engineers and service techs to use for all kinds of electronic work have such poor AC response. I'm sure that there are still laboratory-grade digital multimeters that cover the audio band, ** It's a basic requirement that analogue multimeters can all do. Most analogue multimeters cover at least the audio band and beyond, so if you can hear a sound coming from a loudspeaker, the meter will measure the signal True, but a decent one is more expensive than a digital multimeter, ** No, they can all do it. Makers decided to "penny pinch" early DMMs, simply not mention the limited AC bandwidth and got away with it. So called True RMS models are usually no better for the same reason. In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. ** Excellent. For my article, I was reluctant to suggest buying a 50 year old analog meter that could handle the full audio range, for fear that I'd soon have to write an article about repairing antique test equipment. ** The only hard to get / repair item is the moving coil meter itself. 12AU7s and 6AL5s are cheap & readily available, the 10uF PSU electro and selenium rectifier might need replacing. BTW: Ever try to test the resistance of a speaker in a noisy room with a DMM ?? Do you know what happens? ..... Phil |
#57
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Crosstalk in snake cable that include speaker cables and miccables
On 10/06/2018 12:11 AM, Mike Rivers wrote:
On 6/8/2018 9:25 PM, Trevor wrote: Since it is difficult/expensive to calibrate either, you are probably just as well off using your ears and making a guess. It's difficult to calibrate to the standards required by the Music Police for writing tickets, but with a loudspeaker, pink noise source, and a hardware SPL meter (all of which I have) you can make a rough calibration that will be good enough to let you know, after listening all day and your ears are getting dull, if things are getting too loud. The AudioControl app (that doesn't work on my present phone) tracked my calibrated SPL meter quite well. Is it really currently calibrated to any national standard? Or just a sheet that came with the instrument and completely useless for any legal purpose? I can calibrate any of the other SPL phone apps at a single point and they're repeatable at that SPL, but because the AGC isn't disabled, lower levels are boosted and higher levels are sat on before they get to the meter app, so everything comes out at about the same reading. :-) Exactly, and the vast majority of users don't even have a way to check them at ANY level, yet still think they have a useful measurement. :-( Trevor. |
#58
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Crosstalk in snake cable that include speaker cables and miccables
On 10/06/2018 2:36 AM, Ralph Barone wrote:
The iPod touch is an iPhone without the phone bits. It runs iOS. Oh, obviously I haven't been keeping up with Apple products. (never bought anything they make, I doubt I ever will) I wonder how big a market there is for a crippled iPhone though? Sort of an iPad with too small a screen to be useful by the looks. But too big and expensive for the people that usually buy music players. Everybody that wants to use a phone size player already has a phone that does that I would think. And in the Android world you can just plug a huge micro SD card into most phones for unlimited storage. (swapping cards if really necessary, not something Apple allows because they make so much money on selling memory at hugely inflated prices.) Trevor. |
#59
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Crosstalk in snake cable that include speaker cables and miccables
In article , Trevor wrote:
On 10/06/2018 12:48 PM, Mike Rivers wrote: On 6/9/2018 6:29 PM, Phil Allison wrote: In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. The AVO meters were the most common in places I worked. Still have my AVO model 8. If you don't fry them, no reason they won't outlast the user. I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier. I do keep a Simpson 260 on my bench and I use it often. It lets you see trends, count capacitor discharge curves, and so forth. The comparatively low impedance means it won't get false measurements through leakage. But it's just a coil of wire inside a magnet, there's no active electronics in there. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#60
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Crosstalk in snake cable that include speaker cables and mic cables
Scott Dorsey wrote:
Phil Allison wrote: In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. The AVO meters were the most common in places I worked. Still have my AVO model 8. If you don't fry them, no reason they won't outlast the user. I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. ** Once the tubes in the meter have warmed up, DC balance should be steady. Zeroing the ohms ranges is needed with VOMs too. Modern high-impedance DMMs make my life so much easier. ** The single biggest time saver is the auto-ranging feature. However, most are poor at in-circuit testing resistors and semi junctions. I do keep a Simpson 260 on my bench and I use it often. ** I have a similar Japanese made multimeter that I use occasionally. Taut band, 20kohms/V, 100kHz response plus dBm scale. The ohms x 1 range will reliably forward bias semiconductor junctions while in circuit. ..... Phil |
#61
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Crosstalk in snake cable that include speaker cables and mic cables
On Sun, 10 Jun 2018 17:03:41 -0700 (PDT), Phil Allison
wrote: I do keep a Simpson 260 on my bench and I use it often. ** I have a similar Japanese made multimeter that I use occasionally. Taut band, 20kohms/V, 100kHz response plus dBm scale. The ohms x 1 range will reliably forward bias semiconductor junctions while in circuit. For in-circuit testing I find it useful to have an ohms range that is of low enough voltage that it can't forward bias a junction. I have a separate range that does provide forward bias, and reads out a voltage rather than a resistance. d --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#62
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Crosstalk in snake cable that include speaker cables and mic cables
Don Pearce wrote:
Phil Allison I do keep a Simpson 260 on my bench and I use it often. ** I have a similar Japanese made multimeter that I use occasionally. Taut band, 20kohms/V, 100kHz response plus dBm scale. The ohms x 1 range will reliably forward bias semiconductor junctions while in circuit. For in-circuit testing I find it useful to have an ohms range that is of low enough voltage that it can't forward bias a junction. I have a separate range that does provide forward bias, and reads out a voltage rather than a resistance. ** The diode check range ? Limited current ( typ under 1mA) makes them near useless for in circuit and other work. ** FYI: If you connect say a 100 ohm pot wired as a rheostat to the ohms x 1 range of an analogue multimeter, plus monitor the voltage across the probes with another meter ( say a DMM) you can arrive at DC voltages corresponding to various ohm readings. Then you can carefully mark another scale just above the ohms one- in my case up to about 2.2 volts. Checks Ge and Si diodes, BJTS & Darlingtons and LEDs except with blue or white ones. ---------------------- When repairing an amplifier suspected of having blown BJT outputs & drivers, plus various small signal types and diodes in the SOA limiter - I found a meter that reliably forward biases junctions is needed to find the bad ones. BJTs can fail with junctions shorted or open, plus C-E shorts - an analogue meter gives unambiguous readings with these conditions while a DMM gives mostly ambiguous ones, when testing in circuit. Even if the DMM has a "diode check" range, the current is limited to under 1mA. Either this is insufficient to bias the junction/s or a low value resistor in parallel the draws all the current. Darlington power transistors read like single BJTs devices with "diode check" due to inbuilt resistors bridging B-E junctions. High voltage BJTS ( eg horizontal defection ) have 30 to 100ohm resistors across the B-E junction internally. Early Phase Linear models had output BJTS with inbuilt 70 ohm B-E resistors as well as 10 ohms across parallel sets on the PCB. ..... Phil |
#63
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Crosstalk in snake cable that include speaker cables and miccables
On 10/06/2018 10:06 PM, Scott Dorsey wrote:
In article , Trevor wrote: On 10/06/2018 12:48 PM, Mike Rivers wrote: On 6/9/2018 6:29 PM, Phil Allison wrote: In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. The AVO meters were the most common in places I worked. Still have my AVO model 8. If you don't fry them, no reason they won't outlast the user. I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier You could say that about digital CRO's Vs analog ones too. Spent a lot of time adjusting CRO's before you'd even attempt to use it. I do keep a Simpson 260 on my bench and I use it often. It lets you see trends, count capacitor discharge curves, and so forth. The comparatively low impedance means it won't get false measurements through leakage. But it's just a coil of wire inside a magnet, there's no active electronics in there. To be fair the AVO's were not VTVM's, just a meter, multipliers and shunts. But you did need a VTVM/SSVOM or CRO when loading was a problem. Not something people often worry about these days with modern digital multi-meters, even when they should. 10Mohm is a lot better than 20kohm/volt in most cases, but if you are working with Megohm plus impedances, you still need to know about loading. Amazing how many people get caught out still. Trevor. |
#64
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Crosstalk in snake cable that include speaker cables and mic cables
Trevor wrote:
I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier You could say that about digital CRO's Vs analog ones too. Spent a lot of time adjusting CRO's before you'd even attempt to use it. ** The exact opposite is true. Analoge scopes ( CROs to some) are easy and quick to use, no ambiguous stuff on the screen to worry about. With a DSO, one fiddles about with the controls and menus for ever. To be fair the AVO's were not VTVM's, ** VTVMs waayy outperform AVOs when it comes to electronics, especially with high impedance or valve circuitry. However, they shine with electrical gear like motors, relays, transformers lighting etc. Old school. But you did need a VTVM/SSVOM or CRO when loading was a problem. Not something people often worry about these days with modern digital multi-meters, even when they should. 10Mohm is a lot better than 20kohm/volt in most cases, but if you are working with Megohm plus impedances, you still need to know about loading. Amazing how many people get caught out still. ** Say you have an audio triode valve with 250V on the anode fed from a 470kohm resistor. Both a VTVM and a modern DMM will show 5% or more low on the actual anode voltage. So will a 20kohm/VOM set to its 500V range. ..... Phil |
#65
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Crosstalk in snake cable that include speaker cables and mic cables
Those darn things would break into spurious oscillation driving a resistive load. I came up with a mod that made them stable enough that a local rock band used them as their main amps. so what was the mod? m |
#66
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Crosstalk in snake cable that include speaker cables and mic cables
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#67
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Crosstalk in snake cable that include speaker cables and mic cables
so what was the mod? m I did these mods back in the 1970s and then I had a near photographic memory so I didn't document it. It consisted of installing pico value caps in various locations. I can't remeber the locations or values of the caps. there is some interesting info in this book file:///C:/USER/DOWNLOADS%20go%20here/elebda3.net-gh-238.pdf especially Chap 17, the section on electronic overload protection. If done correctly it looks like a modern design should be immune to damage, even if it does go into osc. m |
#68
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Crosstalk in snake cable that include speaker cables and miccables
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#69
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Crosstalk in snake cable that include speaker cables andmic cables
Trevor wrote:
On 12/06/2018 5:37 AM, wrote: there is some interesting info in this book file:///C:/USER/DOWNLOADS%20go%20here/elebda3.net-gh-238.pdf Do you actually expect everybody to have access to your hard drive? Trevor. Just the NSA... |
#70
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Crosstalk in snake cable that include speaker cables and miccables
In article ,
Scott Dorsey wrote: In article , Trevor wrote: On 10/06/2018 12:48 PM, Mike Rivers wrote: On 6/9/2018 6:29 PM, Phil Allison wrote: In the 1950s and 60s, the standard bench instrument for professional techs and engineers was a VTVM like this one: https://www.radiomuseum.org/r/rca_se...st_wv_98c.html I have one of those on my workbench, and it still works. The AVO meters were the most common in places I worked. Still have my AVO model 8. If you don't fry them, no reason they won't outlast the user. I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier. I do keep a Simpson 260 on my bench and I use it often. It lets you see trends, count capacitor discharge curves, and so forth. The comparatively low impedance means it won't get false measurements through leakage. But it's just a coil of wire inside a magnet, there's no active electronics in there. --scott -- Scott, I'm surprised at your comments about VTVM's. I have several RCA WV-97A's and one WV-98C; and all have been plug-n-play bulletproof since I got them up to snuff about 25 years ago. The VTVM's that gave grief (of those I've dealt with) were the H-P 400 series AC RMS meters. Those were built with vitamin noise, and while I chased down and cured several, I never was satisfied. Big problem was ground lugs rivetted to aluminum. I may sound prejudiced because I worked for Tektronix in the 1960's, but a lot of H-P stuff was rather poorly made. A 200CD audio oscillator was very nice---after you replaced all the postage stamp capacitors and carbon resistors. I added either terminal strips or Tek ceramic strips (pirated from junk K plug ins) for mounting the central electronics. One exception is the h-P 412A DC VTVM. Once working, those are rock-solid. But for AC RMS, a Ballantine 300 beats the H-P 400 all day, even if they look archaic. For passive VOM's, my treasures are a Triplett 630-NA (the model with the double sensitivity switch) and Simpson 260-8. I bought the 260-8 new because it has a 25 volt range suitable for automotive use. Had to wait for the Ojibwas, who make them now, to come back from pow-wow and refill the pipeline, but it was well worth the wait. Both reside in padded cases, also well worth the cost. I have a couple of cheap analog "beater meters" as well, but the 630-NA and 260 are crown jewels around here. DMMs? I just plain don't like them. If I'm chasing intermittents, a DMM doses me with spinning numbers, while an analog meter pointer movement doubles as a poor man's low-frequency oscilloscope. And I don't like being foxed by autoranging. I have to wonder, what were the VTVM's that gave you so much grief. One reason I have for so many RCA's is that when I am bringing up a Tek 530-540 series scope for the first time, I have a meter on every power supply ready to read the moment the time delay closes. Hank |
#71
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Crosstalk in snake cable that include speaker cables and miccables
On 12/06/2018 1:50 PM, Ralph Barone wrote:
Trevor wrote: On 12/06/2018 5:37 AM, wrote: there is some interesting info in this book file:///C:/USER/DOWNLOADS%20go%20here/elebda3.net-gh-238.pdf Do you actually expect everybody to have access to your hard drive? Just the NSA... :-) I doubt they bother to read this group though. You'd need to use the words they auto flag. Oh wait, maybe your use of "NSA" did that already. :-) Trevor. |
#72
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Crosstalk in snake cable that include speaker cables and mic cables
On Tuesday, June 12, 2018 at 2:45:24 AM UTC-4, Trevor wrote:
On 12/06/2018 1:50 PM, Ralph Barone wrote: Trevor wrote: On 12/06/2018 5:37 AM, wrote: there is some interesting info in this book file:///C:/USER/DOWNLOADS%20go%20here/elebda3.net-gh-238.pdf Do you actually expect everybody to have access to your hard drive? Just the NSA... :-) I doubt they bother to read this group though. You'd need to use the words they auto flag. Oh wait, maybe your use of "NSA" did that already. :-) Trevor. whoops sorry about that try this http://www.kelm.ftn.uns.ac.rs/litera...gnHandbook.pdf or google power amplifier design handbook, there is a newer edition out there. m |
#73
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Crosstalk in snake cable that include speaker cables and mic cables
wrote:
there is some interesting info in this book ** You did a Google word search to find that - right ? file:///C:/USER/DOWNLOADS%20go%20here/elebda3.net-gh-238.pdf especially Chap 17, the section on electronic overload protection. ** That is all in Chap 13. If done correctly it looks like a modern design should be immune to damage, even if it does go into osc. ** ********. The Chap does not even mention the topic of positive feedback amplifier oscillation. Google can't know things that and neither do you. ..... Phil |
#75
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Crosstalk in snake cable that include speaker cables and miccables
In article , Trevor wrote:
On 10/06/2018 10:06 PM, Scott Dorsey wrote: I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier You could say that about digital CRO's Vs analog ones too. Spent a lot of time adjusting CRO's before you'd even attempt to use it. I disagree. I spend forever fiddling with the damn menus on the DSO. I like the DSO for a lot of things, especially for very low frequency stuff and the ability to get power spectra, but I'll take an analogue scope any time for making quick qualitative measurements. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#76
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Crosstalk in snake cable that include speaker cables and mic cables
In article ,
Chuck wrote: On Mon, 11 Jun 2018 06:56:43 -0700 (PDT), wrote: Those darn things would break into spurious oscillation driving a resistive load. I came up with a mod that made them stable enough that a local rock band used them as their main amps. so what was the mod? I did these mods back in the 1970s and then I had a near photographic memory so I didn't document it. It consisted of installing pico value caps in various locations. I can't remeber the locations or values of the caps. I think there's only one global feedback loop and then local feedback on the finals, so there are a limited number of poles in the system for you to move around. Should not be too hard to figure out how to make it stable especially with modern test equipment. BUT.... you'll never fix the horrible crossover distortion on those things. Well, maybe you could by redesigning the output stage, but then you might as well just get a good amp. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#77
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Crosstalk in snake cable that include speaker cables and miccables
In article , Trevor wrote:
On 13/06/2018 12:19 AM, wrote: http://www.kelm.ftn.uns.ac.rs/litera...gnHandbook.pdf or google power amplifier design handbook, there is a newer edition out there. Yes, thanks for that. Have an old printed edition myself, never bothered to look for a newer edition on-line before. Are we talking Doug Self's book here? If so, you should buy the printed edition instead of bootlegging it, because Self is a good fellow and deserves your support. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#78
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Crosstalk in snake cable that include speaker cables and mic cables
On 13 Jun 2018 09:31:56 -0400, (Scott Dorsey) wrote:
In article , Trevor wrote: On 10/06/2018 10:06 PM, Scott Dorsey wrote: I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier You could say that about digital CRO's Vs analog ones too. Spent a lot of time adjusting CRO's before you'd even attempt to use it. I disagree. I spend forever fiddling with the damn menus on the DSO. I like the DSO for a lot of things, especially for very low frequency stuff and the ability to get power spectra, but I'll take an analogue scope any time for making quick qualitative measurements. --scott The auto scale button on my Rigol takes me right where I need to be 99% of the time. d --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#79
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Crosstalk in snake cable that include speaker cables and miccables
On 13/06/2018 11:31 PM, Scott Dorsey wrote:
In article , Trevor wrote: On 10/06/2018 10:06 PM, Scott Dorsey wrote: I hope I never, ever have to use a VTVM ever again. I spent more time balancing and zeroing than taking measurements, it seemed. Modern high-impedance DMMs make my life so much easier You could say that about digital CRO's Vs analog ones too. Spent a lot of time adjusting CRO's before you'd even attempt to use it. I disagree. I spend forever fiddling with the damn menus on the DSO. I like the DSO for a lot of things, especially for very low frequency stuff and the ability to get power spectra, but I'll take an analogue scope any time for making quick qualitative measurements. Fair point, adjusting settings via menu's can be a pain. I was thinking of the fact you no longer have to adjust beam focus, vertical position etc. But you still have to adjust probe compensation I guess. So you're probably right. Trevor. |
#80
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Crosstalk in snake cable that include speaker cables and miccables
On 13/06/2018 11:35 PM, Scott Dorsey wrote:
In article , Trevor wrote: On 13/06/2018 12:19 AM, wrote: http://www.kelm.ftn.uns.ac.rs/litera...gnHandbook.pdf or google power amplifier design handbook, there is a newer edition out there. Yes, thanks for that. Have an old printed edition myself, never bothered to look for a newer edition on-line before. Are we talking Doug Self's book here? If so, you should buy the printed edition instead of bootlegging it, because Self is a good fellow and deserves your support. As I said, I already have a printed copy. Just wanted to see what may have been added in a newer edition. Certainly no real need for me to buy a new printed copy these days, not doing that design work any more. I have far too many copies of the same books in various editions as it is. :-( Trevor. |
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