Tico's question seems to imply that my associates or I might deliberately design in products to fail after a certain time. I have never seen this at any time in my 50 year old career as a design professional, and from an consumer audio point-of-view I don't even know how it could be done deliberately. Yes, sometimes components fail, and sometimes they fail sooner rather than later, because they are abused, usually by over-temperature, but sometimes the PARTS MANUFACTURERS have a series of parts that fail, because of some mistake they made in manufacturing.
It so happens that something like this happened with the original Levinson JC-2 preamp. In those early days, 1973-1976 we had design secrets that were difficult, or impossible to patent. So, we ecapsulated our parts and the circuit board in thermal epoxy to keep out prying eyes. This worked fine for a year or so, but then we started getting module failures, after some months of continuous operation. It was traced to a defective jfet epoxy formulation that contained an active agent. It was like a time bomb. Siliconix told me that they lost 1/2 million parts until they fixed the problem, but that did not help us in regard to module failure. These were maybe 50 cent parts, but the modules were worth $50 or more. This completely freaked out Mark Levinson who decided to avoid plastic fets altogether in future, but to use the metal can equivalents that were available at the time at a much higher price. Then, apparently he decided NOT to ecapsulate the components, but to just put them directly on the board. I think that he over-reacted, but I can't really blame him.
However, to have a product run continuously for 30 years, without the caps failing at least, is pretty good reliability.
For the record, the SCP-1 was a pre-preamp, NOT an equalized phono preamp like the SCP-2 which is better known, but it was made from the same input circuit boards as the SCP-2. Our improvements over the SCP-1 product life was different board material and covering (tin to gold), and improved power supplies with bigger transformers and caps.
All the SCP-2 products started out from the best SCP-1's, but they were also improved over the next 5 years until discontinued with different upgrades and we found them to be useful. Still failures sometimes occur, but, thank goodness, not as many as the original Levinson JC-2 modules.
It so happens that something like this happened with the original Levinson JC-2 preamp. In those early days, 1973-1976 we had design secrets that were difficult, or impossible to patent. So, we ecapsulated our parts and the circuit board in thermal epoxy to keep out prying eyes. This worked fine for a year or so, but then we started getting module failures, after some months of continuous operation. It was traced to a defective jfet epoxy formulation that contained an active agent. It was like a time bomb. Siliconix told me that they lost 1/2 million parts until they fixed the problem, but that did not help us in regard to module failure. These were maybe 50 cent parts, but the modules were worth $50 or more. This completely freaked out Mark Levinson who decided to avoid plastic fets altogether in future, but to use the metal can equivalents that were available at the time at a much higher price. Then, apparently he decided NOT to ecapsulate the components, but to just put them directly on the board. I think that he over-reacted, but I can't really blame him.
However, to have a product run continuously for 30 years, without the caps failing at least, is pretty good reliability.
For the record, the SCP-1 was a pre-preamp, NOT an equalized phono preamp like the SCP-2 which is better known, but it was made from the same input circuit boards as the SCP-2. Our improvements over the SCP-1 product life was different board material and covering (tin to gold), and improved power supplies with bigger transformers and caps.
All the SCP-2 products started out from the best SCP-1's, but they were also improved over the next 5 years until discontinued with different upgrades and we found them to be useful. Still failures sometimes occur, but, thank goodness, not as many as the original Levinson JC-2 modules.
The evil as **** Behringer company certainly designs in failure into who knows how many products (that they stole the design of any way).
As far as others doing it? I've never seen purposely poorly made transformers and stuff like that... caps go bad nothing you can do about that. Sometimes you see a manufacturing defect, but that's no big deal.
I'm glad DP270 is time tested at this point...
As far as others doing it? I've never seen purposely poorly made transformers and stuff like that... caps go bad nothing you can do about that. Sometimes you see a manufacturing defect, but that's no big deal.
I'm glad DP270 is time tested at this point...
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No, but I have been interested to get one since a long time.
Decades ago I built a milligauss meter (uncalibrated) for investigating household audio frequency EMR.
I used a stripped down car ignition coil as the pickup and this proved to be usefully sensitive and directional.
Street wires were perfectly audible from 30m away and the local electric railway wires were also perfectly audible from 100m away....trains could be heard leaving stations along the whole line - the intensity and spectrum/tone changed according to the load on the HV aerial lines.
Loudspeakers kick out audio modulated magnetic field quite some distance...is sitting at the intersecting magnetic fields focal point (toed in speakers) part of the audio experience ?.
Dan.
made me wonder about such speaker cables near(?) low level signal wires could have consequences.
-RM
Recently I used a cassette head connected to my N&D test set (as preamp) and took a listen on the monitor output when placed near to wires etc.
Quite illuminating and an experiment I will further visit in the near future.
I'm also going to experiment with ACS712 isolated current transducer.
Right now I'm having fun remastering some recordings via SRC2496 with differing cables in send/return loop and capturing to HD.
Dan.
Quite illuminating and an experiment I will further visit in the near future.
I'm also going to experiment with ACS712 isolated current transducer.
Right now I'm having fun remastering some recordings via SRC2496 with differing cables in send/return loop and capturing to HD.
Dan.
I doubt it are the Fets as I found metal can Fets in defective modules I did open. I can understand Mark Levinson freaked out as he was proud being a high-end company. It got got even worse as a customer of me had to wait a year(!) for a new line module. It seems the later line modules were designed by Tom Colangelo. I did not hear these later modules fail in the field.
I also have a power supply module from the JC2 that has deep cracks. Swelling electrolytic capacitors??
Well Tico, you might have found something different, but the modules that I just inspected (from that time and unencapsulated) both phono and line, have only plastic jfets or bipolar transistors in them. I did use some metal can output devices in the Grateful Dead (+/- 24V) modules that Mark made for us in 1973. It seemed impractical to use metal can devices at the time, because they cost so much more for the same device performance, until the modules started to fail and Mark panicked.
As far as the power supply is concerned, we did not make these modules. Mark for several years used an outside vendor for these, so that we potentially would not have to worry about any legal problems if something went wrong. Did you open one of these modules? Later modules were designed by Tom Colangelo, and they probably used metal can devices.
As far as the power supply is concerned, we did not make these modules. Mark for several years used an outside vendor for these, so that we potentially would not have to worry about any legal problems if something went wrong. Did you open one of these modules? Later modules were designed by Tom Colangelo, and they probably used metal can devices.
Tico, on second thought, are you referring to the internal phono power supply buffer module as the power supply module? That would make sense, since it contained 2 rather large electrolytic caps (of dubious design quality as they were purchased before Japan took over the field). They were practically 'babied' in the circuit with a regulated supply never exceeding 15V and a large series resistor, but who knows how the caps would behave over time?
OS, I don't have any specific mod to sweeten up a component when it comes across as sterile. My biggest mods are Bybee based, and I do recommend them, but maybe a different cap or resistor in an important position might be useful. Always use hi speed soft recovery rectifiers when possible.
Have you found that some people just straight up like very fatiguing sound because to the it simply sounds like there is high frequency information to them?
I believe for a somewhat significant amount of people that is essentially the case in that everytime you try and make it better they think it's worse. For example throw in a power conditioner to reduce all the exaggeration of high frequencies that are coming across as harsh, and they say it sounds like a loss of dynamics and compression... where as for many of us it simply makes it tolerable to even listen to.
A lot of horn lovers may fit in this camp. One of the worst experiences I've ever had with music was with a bunch of field coil horns. Frankly I think they often sound even more dry than many things.
Another example might be movie theaters. Generally they sound ok, sometimes good, with some material. But I often think they need power conditioning because it's a bit harsh. The people that are the other way think when they sound easier to listen to, that they're compressed or something.
I don't believe one is "right" or "wrong" it's just interesting that, well, what do you do? You basically need two product lines.
I believe for a somewhat significant amount of people that is essentially the case in that everytime you try and make it better they think it's worse. For example throw in a power conditioner to reduce all the exaggeration of high frequencies that are coming across as harsh, and they say it sounds like a loss of dynamics and compression... where as for many of us it simply makes it tolerable to even listen to.
A lot of horn lovers may fit in this camp. One of the worst experiences I've ever had with music was with a bunch of field coil horns. Frankly I think they often sound even more dry than many things.
Another example might be movie theaters. Generally they sound ok, sometimes good, with some material. But I often think they need power conditioning because it's a bit harsh. The people that are the other way think when they sound easier to listen to, that they're compressed or something.
I don't believe one is "right" or "wrong" it's just interesting that, well, what do you do? You basically need two product lines.
The usual criticism of an analytically accurate component, add some euphonic distortion to sweeten the pot.
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