Re: Re: Re: Battery sound?
A 12V/7Ah will typically have ca 100mOhms, not well below. And remember you'll usually have to put several in series to get your desired voltage, so this will add up. How important this is depends of course on the application, but I'd say for a class B or AB amp drawing substantial current peaks, this is more than you'd probably want. IMHO, YMMV, etc...Steve Eddy said:
Re: Re: Re: Re: Battery sound?
Anyone know how linear their ESR are over a wider frequency range...say 10hz>100,00kHz?
I found I needed to add both electrolyts and film caps.
Verbal said:
A 12V/7Ah will typically have ca 100mOhms, not well below. And remember you'll usually have to put several in series to get your desired voltage, so this will add up. How important this is depends of course on the application, but I'd say for a class B or AB amp drawing substantial current peaks, this is more than you'd probably want. IMHO, YMMV, etc...
Anyone know how linear their ESR are over a wider frequency range...say 10hz>100,00kHz?
I found I needed to add both electrolyts and film caps.
I've always been skeptical of battery power.
Also, batteries are expensive - a single 12V 7AH SLA costs almost as much as a nice 255VA 25-0-25V transformer. Thsoe who follow my regular ranting will figure out quickly enough that I don't have access to toroids, well, I do, if I need a thousand of them.
I've been testing some new STK4191 amps using a discman. All of yesterday the tests have been through the mains adapter. Just so I could drain some Nicd AA batteries which were laying about, I powered the discman through them.
Suffice it to say that I am now looking for batteries for another amp of mine...
Also, batteries are expensive - a single 12V 7AH SLA costs almost as much as a nice 255VA 25-0-25V transformer. Thsoe who follow my regular ranting will figure out quickly enough that I don't have access to toroids, well, I do, if I need a thousand of them.
I've been testing some new STK4191 amps using a discman. All of yesterday the tests have been through the mains adapter. Just so I could drain some Nicd AA batteries which were laying about, I powered the discman through them.
Suffice it to say that I am now looking for batteries for another amp of mine...
I don't have firsthand experience with batteries, but it seems to me that they would make excellent power supply filters.
I've been wondering about using constantly charged battery power--IOW, inserting batteries in series with the + and - of an otherwise noisy dc power supply.
Since batteries function by the relatively slow process of ion diffusion, wouldn't series batteries remove all but extremely low-frequency ripple?
If this is so, why not use a battery supply that is constantly being supplied by a simple float charging circuit? You could skip the concerns of charging cycles.
Would the batteries pass noise? Anyone ever scope the output of a battery in series with noisy DC?
I've been wondering about using constantly charged battery power--IOW, inserting batteries in series with the + and - of an otherwise noisy dc power supply.
Since batteries function by the relatively slow process of ion diffusion, wouldn't series batteries remove all but extremely low-frequency ripple?
If this is so, why not use a battery supply that is constantly being supplied by a simple float charging circuit? You could skip the concerns of charging cycles.
Would the batteries pass noise? Anyone ever scope the output of a battery in series with noisy DC?
Interesting idea but how would you implement that? If the charger is hooked up to the batteries wouldn't you get the output of your charger across the terminals and thus as your power supply.
Ion diffusion is actually extremely fast. It is charge diffusion that actually occurs, not the movement of individual ions.
Vic
Ion diffusion is actually extremely fast. It is charge diffusion that actually occurs, not the movement of individual ions.
Vic
Re: Re: Re: Re: Battery sound?
Well, the Panasonic LC-R127P has an internal resistance of 26 milliohms. I don't know about you, but I'd consider 26 to be well below 100. And the higher the Ah rating, the lower the internal resistance. Their 28Ah LC-XC1228AP has an internal resistance of 6 millioms.
Ok, with 3 in series, that's 78 milliohms. Still nothing to lose sleep over in my opinion.
What's the class of operation have to do with anything?
se
Verbal said:
Well, the Panasonic LC-R127P has an internal resistance of 26 milliohms. I don't know about you, but I'd consider 26 to be well below 100. And the higher the Ah rating, the lower the internal resistance. Their 28Ah LC-XC1228AP has an internal resistance of 6 millioms.
Ok, with 3 in series, that's 78 milliohms. Still nothing to lose sleep over in my opinion.
How important this is depends of course on the application, but I'd say for a class B or AB amp drawing substantial current peaks, this is more than you'd probably want. IMHO, YMMV, etc...
What's the class of operation have to do with anything?
se
Bill F. said:
In <b>SERIES</b> with the + and -? Or do you mean across them same as you'd use regular filter capacitance?
Well, batteries don't draw current until the voltage across them his greater than their internal voltage so if your "noisy DC power supply" were across them, you'd still end up with ripple voltage.
See above.
se
Re: Re: Re: Re: Re: Re: Battery sound?
My experiance comes from 2*250W power amp.
Have you actually tried with and without caps?
The reason for asking was to compare to capacitors, I have not been able to obtain any spec showing ESR at different frequencies for sla batteries.
It is a common and very important metrics on caps.....
Steve Eddy said:
My experiance comes from 2*250W power amp.
Have you actually tried with and without caps?
The reason for asking was to compare to capacitors, I have not been able to obtain any spec showing ESR at different frequencies for sla batteries.
It is a common and very important metrics on caps.....
One thing to think of, if any of you has read the thread on protection power fuses, is how to protect the speakers in case of some problem with the batteries. In AC power you can use a single fuse on the primary and protect it all.
With batteries you would need two fuses, one for each rail.
If a fuse fails, the danger of sending DC to the output, and the speakers, sounds as very real and present. Isn't that so?
Perhaps some relay protected output should be in order, shutting the output off if any DC is present, for battery power.
Carlos
With batteries you would need two fuses, one for each rail.
If a fuse fails, the danger of sending DC to the output, and the speakers, sounds as very real and present. Isn't that so?
Perhaps some relay protected output should be in order, shutting the output off if any DC is present, for battery power.
Carlos
Re: Re: Re: Re: Re: Battery sound?
Also this is at 1kHz. A8 rises a good point, they may get worse at higher frequencies...(honestly no idea, though...)
A lot, actually. Class A draws a fairly constant current, while you'll find half a cycle of your output waveform on your supply voltage with a class B amp and high power supply impedance.
Yes, because Panasonic measures fully charged, while other mfgs seem to use the IEC norm. Below is a chart for a similar battery from the Yuasa VRLA manualSteve Eddy said:
Also this is at 1kHz. A8 rises a good point, they may get worse at higher frequencies...(honestly no idea, though...)
A lot, actually. Class A draws a fairly constant current, while you'll find half a cycle of your output waveform on your supply voltage with a class B amp and high power supply impedance.
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Re: Re: Re: Re: Re: Re: Re: Battery sound?
Ok.
Why? If it's not reproducing anything up to 100kHz and above, why would you care what the ESR is up there?
Also, by the time you get up to 100kHz, ESL begins to swamp out ESR anyway.
That was reproducing 100kHz and above?
I've never tried it with a gob of capacitance. Only with and without about 22uF. Didn't seem to make any difference but I kept it in so I don't have to worry about lead inductance if I ever need to lengthen the power feed lines.
It's an important metric on caps largely because it determines how much heating you'll get and ultimately sets the maximum ripple current the capacitor can handle safely.
se
A 8 said:
Ok.
Why? If it's not reproducing anything up to 100kHz and above, why would you care what the ESR is up there?
Also, by the time you get up to 100kHz, ESL begins to swamp out ESR anyway.
That was reproducing 100kHz and above?
I've never tried it with a gob of capacitance. Only with and without about 22uF. Didn't seem to make any difference but I kept it in so I don't have to worry about lead inductance if I ever need to lengthen the power feed lines.
It's an important metric on caps largely because it determines how much heating you'll get and ultimately sets the maximum ripple current the capacitor can handle safely.
se
Re: Re: Re: Re: Re: Re: Battery sound?
Ok. But by the time you start getting around 100 milliohms, your voltage has already dropped considerably.
Or it may not.
I just go by my own experience and so far, I haven't had any anomalies crop up at high frequencies using batteries.
It may be interesting to see what resistance is at higher frequencies, but I only care about the end result. I listen for my own pleasure, not the pleasure of some piece of test gear.
And the ultimate consequence of this is what exactly?
se
Verbal said:
Ok. But by the time you start getting around 100 milliohms, your voltage has already dropped considerably.
Or it may not.
I just go by my own experience and so far, I haven't had any anomalies crop up at high frequencies using batteries.
It may be interesting to see what resistance is at higher frequencies, but I only care about the end result. I listen for my own pleasure, not the pleasure of some piece of test gear.
And the ultimate consequence of this is what exactly?
se
???
I think of a battery psu for a class a amp.
since i wish to hear musik for more than half an hour without reloading the battery, i need to buy batteries with 100 AH or more.
Does anyone can tell me, if for a test i can connect a car battery directly to my amps? (without using capacitors).
An why does one need big capacitance with car batteries?
thanks
Ralf
vic said:Battery supplies should not cost more than a PSU with a decent quality transformer. Batteries run around $20 each for 12V 7.2Ah. A three phase charger runs about $50.
SE would probably have more informative thngs to say about this than I do. He has much more experience. Maybe he could give his
Vic
I think of a battery psu for a class a amp.
since i wish to hear musik for more than half an hour without reloading the battery, i need to buy batteries with 100 AH or more.
Does anyone can tell me, if for a test i can connect a car battery directly to my amps? (without using capacitors).
An why does one need big capacitance with car batteries?
thanks
Ralf
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