Scott, I am interested in what you have to say about electronic system noise.
System noise can be unpleasant or pleasant, and completely unlike the Youtube tripe you just posted.
Makes me wonder about the mental state of the band, the audiences, and those who buy the records....just sayin'.
You have posted this kind of aural assault before, what is your attraction to this stuff, I can forgive if it's just for testing/assessment purposes.
Dan.
And on a totally different topic, one of my friends who is the chief engineer at one of the largest pro audio manufacturers wants to retire, as has many of his coworkers.
The problem is finding replacements. He has 45 years of useful experience. The folks 10-20 years younger all seem to have gone into computer based engineering. So there are a few folks around hitting forty who went into audio. But they aren't experienced enough to know the full range of stuff needed.
That ranges from the difference between the different pro audio markets such as what does a back ground music concern differ from a church sound trunk slammer to a school market group, even a boardroom installer all the way to crazy guys like me. Then there are engineering issues like rigging loudspeakers, not to mention things like truck pack all the way to meeting codes and standards.
His bosses tried to get him to sign a long term contract, when that didn't work they are now trying to get him to just retire to part time work.
Moral of the story, it is fun to jibe guys like JC about designing as if it is still days gone by, but there really is a breadth of knowledge that comes with lots of experience.
Other weird topic. I have a semi copy of a JC3 preamp in my office. The power company recently upgraded the service to my area. My shop used to be fed from a 4160 volt 3 phase line. This was upgraded to I suspect the newer standard of 13 or so KV line. They also installed "smart meters." The result was not just a hum appeared in the preamp output but also what sounds like a tone modulated by Morse code.
Well in addition to that my headphone amplifier started having a noticable buzz from the power transformer.
To confuse things all this started right as I changed the phono cartridge!
I took the preamp case apart and found that placing a mild steel shield between the power transformer and circuitry had almost no effect. Changing the mounting angle had more effect. The transformer was a flat EI style pulled from a piece of Sony gear.
While open I tried running the power supply lines through a ferrite core. That lowered the "Morse code" noise.
Being a bit slow as to why the noises appeared suddenly, I slept on it.
Next morning I measured the AC line voltage at 129.9 volts with about 5% distortion. Then I dug out my DC on AC tester. Yes there was asymmetric clipping of the power line. So combined with the headphone buzzing hint I realized the small signal transformer cores were saturating. That allowed more flux to escape the core!
I changed the power transformer to one with a higher voltage primary, permanently added the ferrite core and as a last step added filtering to the safety ground wire which it turned out was also bringing noise into the preamp.
To fix the headphone amplifier I just dug out my buck transformer box and set it for minus 6 volts.
Scott,
Sorry for the long post that has nothing to do with automobiles.
The problem is finding replacements. He has 45 years of useful experience. The folks 10-20 years younger all seem to have gone into computer based engineering. So there are a few folks around hitting forty who went into audio. But they aren't experienced enough to know the full range of stuff needed.
That ranges from the difference between the different pro audio markets such as what does a back ground music concern differ from a church sound trunk slammer to a school market group, even a boardroom installer all the way to crazy guys like me. Then there are engineering issues like rigging loudspeakers, not to mention things like truck pack all the way to meeting codes and standards.
His bosses tried to get him to sign a long term contract, when that didn't work they are now trying to get him to just retire to part time work.
Moral of the story, it is fun to jibe guys like JC about designing as if it is still days gone by, but there really is a breadth of knowledge that comes with lots of experience.
Other weird topic. I have a semi copy of a JC3 preamp in my office. The power company recently upgraded the service to my area. My shop used to be fed from a 4160 volt 3 phase line. This was upgraded to I suspect the newer standard of 13 or so KV line. They also installed "smart meters." The result was not just a hum appeared in the preamp output but also what sounds like a tone modulated by Morse code.
Well in addition to that my headphone amplifier started having a noticable buzz from the power transformer.
To confuse things all this started right as I changed the phono cartridge!
I took the preamp case apart and found that placing a mild steel shield between the power transformer and circuitry had almost no effect. Changing the mounting angle had more effect. The transformer was a flat EI style pulled from a piece of Sony gear.
While open I tried running the power supply lines through a ferrite core. That lowered the "Morse code" noise.
Being a bit slow as to why the noises appeared suddenly, I slept on it.
Next morning I measured the AC line voltage at 129.9 volts with about 5% distortion. Then I dug out my DC on AC tester. Yes there was asymmetric clipping of the power line. So combined with the headphone buzzing hint I realized the small signal transformer cores were saturating. That allowed more flux to escape the core!
I changed the power transformer to one with a higher voltage primary, permanently added the ferrite core and as a last step added filtering to the safety ground wire which it turned out was also bringing noise into the preamp.
To fix the headphone amplifier I just dug out my buck transformer box and set it for minus 6 volts.
Scott,
Sorry for the long post that has nothing to do with automobiles.
Last edited:
Hi Richard,
So you want a rat (in the old 70's sense).
Mine was normally aspirated in a '67 Cutlass. Turned mid 12's on street gas and street tires with everything still in the car. Doesn't sound like much, but back then, seeing the biggest Cutlass ever made go that fast was something. Trailing arms and coils in the rear, Monroe 500's all the way around and variable rate springs.
If it wasn't for the power plant, it was a very nice car to drive around. I had another one stock in the same colours. Shared a set of plates and confused the hell out of the neighbors.It chirped the wheels going into drive from park with the brakes full on. It was an animal.
I'd love to make that car again and still have a daily driver.
-Chris
Sounds like fun and not blah blah blah at all. Today I would use an injected crate motor but I would like it in an old 30-40's repo body. I might just buy a kit car roadster to play with when things get boring here.
What did it have for brakes?
-RM
Holy crap, I've still got that issue in the closet somewhere. (You'll have to take my word for it - there is currently a large subwoofer in front of the closet door.)
Proud Dad....
My son, winning second round of local music comp, finals in a few weeks - Comp Two - Video Clip
Prize is DKK 20,000 plus stagecraft/vocal tuition.
The second round win has already given them a performance slot at local Spot Festival - SPOT Festival - DK.
Local Radio interview and live to air performance at 3.00pm today DK time - netradio.radioskive.dk/player/.
Take a look/listen, critique/advice is welcome.
Dan.
My son, winning second round of local music comp, finals in a few weeks - Comp Two - Video Clip
Prize is DKK 20,000 plus stagecraft/vocal tuition.
The second round win has already given them a performance slot at local Spot Festival - SPOT Festival - DK.
Local Radio interview and live to air performance at 3.00pm today DK time - netradio.radioskive.dk/player/.
Take a look/listen, critique/advice is welcome.
Dan.
Fine, I'll dig up some pictures for you, but I'll mail them in a PM to you, so as not to hijack this thread again. Scott is right in remindnig us about that, its quite a subject which needs some elabration to grasp the whole idea and the scope of work which had seven of us working for almost two years. While one man can do it all himself, the result will never be as if seven men each did his best in his field.
It is much more challenging than a phono preamp, I'm afraid.
Matching a volumetric machine, i.e. a piston engine, with two turbomachines in order to reach a specific performance goal has been a challenge for the last 100 years, ever since the first turbocharging (T/C) patent was granted in 1905.
Although there may be some rules of thumb, this is not enough. What is needed is a sort of "LTspice for turbocharging" software, and a library of performance data for all components in the system. While such software exists also in public domain, e.g.
OpenWAM Manual
the component data are much harder to come by. T/C manufacturers normally do not release the turbine and compressor performance maps for competition reasons, and the engine folks do likewise. Not really different from the situation in the field of electronics simulation.
Re. turbo lag, in spite of the progress achieved in the area of turbocharging, a well-made serially-produced aspirated engine still has an edge over a T/C one when accelerating. Several methods are in existence for diminishing the turbolag, but I think that the situation will change with the introduction of small-inertia, electrically driven auxiliary compressors that would provide the shot of air needed when the accelerator is pressed, and then shut off. Such solutions do exist, but they call for a 42V power network in the car.
Hope not to have distracted too much from the main subject of the thread.
Regards,
Braca
Last edited:
Hi Richard,
Drums on all four corners ! Steel belted radials too, BFG somethings. We didn't know that those steel belted tires undid themselves at speed back then. There's another reason why I shouldn't be here to talk about it. Yes, it suffered from serious brake fade.
Noise and dynamic range trade-offs? In my world, reducing noise increases dynamic range.
-Chris
Drums on all four corners ! Steel belted radials too, BFG somethings. We didn't know that those steel belted tires undid themselves at speed back then. There's another reason why I shouldn't be here to talk about it. Yes, it suffered from serious brake fade.
Noise and dynamic range trade-offs? In my world, reducing noise increases dynamic range.
-Chris
Welcome to the modern era. The smart meters transmit RF usually to some nearby hub which goes back to the billing system. but current practice is to use power line communications for control of the switches and the tap changers in the power network. That can be anywhere from 50 KHz to 30 MHz on the power line.
Two things- First you should explore making your stuff resistant to the noise on the power network, its not going away. Second would be to trap the noise where it comes into the facility. A serious inline filter with inductors and caps should be able to stop most of that at the entrance to your distribution box. The peak currents can be several amps at the transmit frequencies so you have some energy to deal with.
The asymmetric clipping on the power is a little odd. And running the line voltage at the max allowed is also questionable. Thats hot enough to cause problems even with MOV's (which are often 130V AC rated MOV's). This is the best document I could find on what to expect: https://www.pge.com/includes/docs/p...ergystatus/powerquality/voltage_tolerance.pdf Your utility may have other ideas.
If the AC is clipped (rectified loads) and still high someone is overcompensating. it can als overhead motors and transformers. You could look at the spectrum of the harmonics and learn more. I have heard that harmonics up to 50 can be significant on power stuff.
Yes it is. Much more difficult. All those things mentioned and more were successfully combined and driven on the street for years... until stricter smog requirments side-lined it. No turbo lag, Nitrous, all of it. I combined turbo parts from different turbo's to get the high boost levels. Rods, pistons, heads all replaced/reworked as was most everything from bumper to bumper. My biggest problem was the clutch would not hold the power and slip when the nitrous was turned on -- a competition racing clutch setup. Dual/triple disc setups didn't exist at that time.
THx-RNMarsh
Last edited:
Scott, I am interested in what you have to say about electronic system noise.
System noise can be unpleasant or pleasant, and completely unlike the Youtube tripe you just posted.
I find it very hard to get any kind of a clean noise floor for any measurements these days unless almost in a clean room environment. I can't help but think this is more important audio than crazy SNR or THD. A little analogy Dan think of the "music" as an audio equivalent of the pollution from smog, etc.
Last edited:
- Status
- Not open for further replies.