Hi John,
I'm thinking more in terms of noise at very low levels. There is a belief that batteries are perfectly quiet, which they really are not. It's not uncommon to see a charger arrangement to the batteries, then straight on to the circuits.
Try the Cyclon type then John. These have to be reliable and are used everywhere in industry. Even medical devices have used these and they are reliable. I wonder what Lithium batteries are like? They are new and promise very reliable operation. I have not tested any for noise. I do see that HP uses this type for memory backup (non-rechargeable) and they last 10 years and longer.
Did you download the applications manual I linked to?
-Chris
I'm thinking more in terms of noise at very low levels. There is a belief that batteries are perfectly quiet, which they really are not. It's not uncommon to see a charger arrangement to the batteries, then straight on to the circuits.
Try the Cyclon type then John. These have to be reliable and are used everywhere in industry. Even medical devices have used these and they are reliable. I wonder what Lithium batteries are like? They are new and promise very reliable operation. I have not tested any for noise. I do see that HP uses this type for memory backup (non-rechargeable) and they last 10 years and longer.
Did you download the applications manual I linked to?
-Chris
Anatech, I make fairly sophisticated power supplies with NO center taps, hi speed diodes, Pi passive and active filtering, or 6 levels. Still, I am not sure that it is power-line proof. Maybe.
However, I KNOW that my STAX Lambda Headphone Amplifier is VERY sensitive to line cords. Did the tests, myself. Why, I don't know.
I am not currently using batteries, except in portable equipment, nor do I plan to. However I did download your battery manual. Thank you.
However, I KNOW that my STAX Lambda Headphone Amplifier is VERY sensitive to line cords. Did the tests, myself. Why, I don't know.
I am not currently using batteries, except in portable equipment, nor do I plan to. However I did download your battery manual. Thank you.
I second that!
Anatech it would be nice if you can eleborate on proper PSU design and your personal findings, so that we may all learn.
I think it is good to hear different approaches which can give birth to new and fresh ideas for reaching similar or even better results.
Thanks so far.
Franklin
Anatech it would be nice if you can eleborate on proper PSU design and your personal findings, so that we may all learn.
I think it is good to hear different approaches which can give birth to new and fresh ideas for reaching similar or even better results.
Thanks so far.
Franklin
janneman said:
I tried to use them in a cascode circuit to bias the mosfets. I had a 250uF cap in parallel with the battery, but there was still some high frequency noise at the output and it was very irritating - hurt my ears. I put a resistor between the battery and the cap but this made it less irritating but it sounded worse. So, I resistor biased it, and got beautiful sounds.
john curl said:
At least, education was sometimes better, especially when we were taught a broad range of things. Narrow minded designer would be afraid to design something that requires one extra operation on assembly line because a technologist would slap his hand. Also, yesterday after the concert sitting around the table we discussing sound quality the artist was pleased by we remembered Tomsk, a town surrounded by taiga (a deep forest): the artist was there when a theater worked on his play. Tomsk had unique set of plants, scientific, and educational institutions, so the same people participated in research, manufacturing, and teaching, sharing new discoveries and old wisdom. I did not value it then, but now I understand how unique and genuine if was organized.
However, private entrepreneurship was forbidden by law (exploitation of poor people by private business), so I was always under a fear to be caught for making pedals, amplifiers, synthesizers for local musicians...
Sometimes, Wavebourn, we have to be 'practical'. For example, most items in the Western World are not made by hand. That means that individual measurement is more difficult, and is often designed out, if possible. This is one of the the reasons that negative feedback is useful.
For most things, it is OK, but with audio, it can be problematic.
Once, Dick Sequerra, a well known designer-physicist, was contracted by the NAB (National Association of Broadcasters) to build the solid state version of the 'All American 5' (a popular tube radio made for the masses in the '40's and '50's).
This version would use Dick's FM front end, and end with my 'El Cheapo' power amp, that I am, in fact, designing with today, on another project.
Well, instead of using ceramic filters for the IF, he had a tunable transformer. Simple adjustment, I am told, but the design was rejected, because of it. Ask him about it Scott, I may not have all the facts right, it was 20 years ago. You see, we also like easy adjustments, but it sometimes is not practical.
For most things, it is OK, but with audio, it can be problematic.
Once, Dick Sequerra, a well known designer-physicist, was contracted by the NAB (National Association of Broadcasters) to build the solid state version of the 'All American 5' (a popular tube radio made for the masses in the '40's and '50's).
This version would use Dick's FM front end, and end with my 'El Cheapo' power amp, that I am, in fact, designing with today, on another project.
Well, instead of using ceramic filters for the IF, he had a tunable transformer. Simple adjustment, I am told, but the design was rejected, because of it. Ask him about it Scott, I may not have all the facts right, it was 20 years ago. You see, we also like easy adjustments, but it sometimes is not practical.
john curl said:
John, what I am talking about, is very practical. There is a big difference between what is practical for short run of precise and expensive devices, and mass production of cheap consumer products. Different technological approaches are practical for them, and if to involve design in this equation there will be different design criteria as well more practical. Like (back to your example), some radio listeners prefer sound of filters of selectivity arrays in Collins R-390/URR shortwave receivers to electro-mechanical filters in Collins R-390A/URR receivers, though both of them are very expensive military receivers, while formers were designed for audio listening, later mostly used for teletypes. In case of FM (though in something different than All American 5 that was AM only) tuned coils would be preferable to ceramic filters for high-end receivers, when for mass production ceramics would be more preferable.
scott wurcer said:
Do you know Scott that many American villages then did not have AC power?
Edit: and ceramic filters were not available yet. Instead, Motorola used tuned filters molded in epoxy resin in their military airborne receivers, they were called "Permakay". I have one, it looks nice, don't need any adjustment in service, and sounds much better than any modern ceramic filter.
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