John Curl's Blowtorch preamplifier part II - Page 3519 - diyAudio
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Old 16th February 2013, 05:57 PM   #35181
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AND: Using the engineering equation: dV/dt = I/C Let's see how long it can maintain its voltage: Let's say, dV is a change of 1V. Let's say, C=58F, then 1X58 =IXT(in seconds) Then you will droop 1V after 58 seconds with a 1A draw. Not too long. See the problem Let's say instead that we use a battery with 1A-hour capacity. Then it will be equivalent to about 3600F. or about 22 times better.
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Old 16th February 2013, 05:57 PM   #35182
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Jan, I have played around with a couple of different EDL caps and have some left which you may have after returning from your trip to the sun. ESR at DC is pretty low and ESL I don't expect to be much different from Elco's, looking at their construction. I decided not to use them because they self discharge quite quickly.

On batteries in general: regulators like the Jung/Didden or the Sjostrom are already pretty noise free, and if noise were a problem, there is a trick to get it even further down. Also, output impedance of this kind of regulator is pretty good in the whole audio band. The limiting factor here is the wiring between the PS and the current consumers. The impedance of this wiring pushes up the ripple on the supply rails under fluctuating load. There is no way an even better PS or batteries could help out here. The only solution is to put the regulation as close to the current consumers as possible, or, of course, use decoupling caps with small leads near the point of consumption.
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Old 16th February 2013, 06:01 PM   #35183
qusp is offline qusp  Australia
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going by the datasheet 1000000 cycles.
17.8Wh at fully charged
10years life at rated voltage at room temp (25C)
max peak current 2000A for 1sec
max continuous current at 15C 100A
max cont. current at 40C 160A
ESR ~2.1mΩ

^^ for the 500F/16V

given that I dont think in audio applications we would expect much less than the 10 year life as long as the chassis was built with that in mind.

you would never use batteries on noise alone, floating is a bonus for some circuits and again, why does everyone automatically compare a battery, completely by itself with no filtering to a super regulator? wouldnt a fairer comparison be a battery to a rectifier or at best a raw DC supply?

Last edited by qusp; 16th February 2013 at 06:13 PM.
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Old 16th February 2013, 06:05 PM   #35184
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Phased array speaker Patent US7130430 - Phased array sound system - Google Patents
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Old 16th February 2013, 06:15 PM   #35185
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Quote:
Originally Posted by jan.didden View Post
Does anyone know the ESR and ESL of typical supercaps?

jan
Study i did before the invention of super caps was that for fast transients, standard batteries (carbon, mercury, NiCad etc) didnt do well. Must be cap bypassed for speed (and to maintain low Z after discharge time). DC esr was great fully charged.

Last edited by RNMarsh; 16th February 2013 at 06:19 PM.
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Old 16th February 2013, 06:19 PM   #35186
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i'm guessing this was some time ago? before lithium polymer as well?
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Old 16th February 2013, 06:20 PM   #35187
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Quote:
Originally Posted by RNMarsh View Post
Power amplifiers present a unique challenge when using Current-Mode amp circuit with low PSR.
Reason why care have to be kept inside the amp itself with good fast current sources and good voltage filtering near the low power stages, where it is easy and more sensible, specially in current feedback topologies. That is often done in OPAs, where good CFA devices are not so bad rated, regarding PSRR. After that, and with some precautions, it is not so difficult to provide BIG rails with good enough noises. That, for the numbers.
But little changes of signatures are still audible depending of various power supplies topologies, mostly concerning dynamic behaviors during transients. I tend to prefer simple emitter follower stabilization VS feedback regulations. May-be some conflicts between the power supply servo delays and the amps feedback ones. Anyway, care had to be taken, at any steps, to get high speed regulations/filtrations.
For preamp, no real issues, you can find integrated circuits able to provide <15µv rms of noise, like TPS7A30/ TPS7A49. (~ -120dB)
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Last edited by Esperado; 16th February 2013 at 06:38 PM.
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Old 16th February 2013, 06:48 PM   #35188
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Phased array loud speakers have been around for decades.
See the text "Sound system engineering by Don & Carolyn Davis"
( 4th edition soon to be released) http://www.amazon.com/Sound-System-E...em+engineering
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Old 16th February 2013, 07:31 PM   #35189
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Quote:
Originally Posted by vacuphile View Post
regulators like the Jung/Didden or the Sjostrom are already pretty noise free, and if noise were a problem, there is a trick to get it even further down. Also, output impedance of this kind of regulator is pretty good in the whole audio band. The limiting factor here is the wiring between the PS and the current consumers. The impedance of this wiring pushes up the ripple on the supply rails under fluctuating load. There is no way an even better PS or batteries could help out here. The only solution is to put the regulation as close to the current consumers as possible, or, of course, use decoupling caps with small leads near the point of consumption.
Exactly! The only way to make those regs 'better' for the load is either using separate regs at the load point, or remote sensing at the sensitive load point.
The Zout of these babies was about the equivalent of an inch of wiring.
Remote sensing was used in the regs we worked on in 1994, see Home.

jan
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Old 16th February 2013, 07:53 PM   #35190
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or just use sufficiently thick wire and decoupling for the load current in the first place...

nothing wrong with regs, I use mostly regulated supplies, but I just find most of the performance stuff mentioned with regs vs batteries is kinda irrelevant for most cases and if it isnt, regulate the battery. why does AC get a free super regulator for the purpose of comparison?

Last edited by qusp; 16th February 2013 at 07:59 PM.
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