Andrew, thanks for the feedback. The spec sheet did show that at full load the output would be 9.97 VAC.
I agree that there will be a lot of power that would need to be dissipated. I've been looking through the Allied catalog for TO-220 heatsinks that would support this. Unfortunately I wanted to use an R-Core, but could not get one quickly at anything lower than 10 VAC.
I'm using the LT1085 regulator, which is supposed to have a very low dropout voltage, on the order of 1.3 volts. I guess that means I will have to dissipate even more power through the regulator!
I agree that there will be a lot of power that would need to be dissipated. I've been looking through the Allied catalog for TO-220 heatsinks that would support this. Unfortunately I wanted to use an R-Core, but could not get one quickly at anything lower than 10 VAC.
I'm using the LT1085 regulator, which is supposed to have a very low dropout voltage, on the order of 1.3 volts. I guess that means I will have to dissipate even more power through the regulator!
Hi Tonyptony,
no, the low min drop figure simply ALLOWS less transformer voltage.
It does not increase your dissipation.
The dissipation = current times (volts in minus volts out).
The low drop out regulators are (nearly) always based on Sziklai pass devices with the result that the datasheet stipulates much stricter output conditions for the load. Take care. Ordinary regulators are much more tolerant of the load.
My advice, if you don't need the efficiency of low dropout regs then don't use them.
no, the low min drop figure simply ALLOWS less transformer voltage.
It does not increase your dissipation.
The dissipation = current times (volts in minus volts out).
The low drop out regulators are (nearly) always based on Sziklai pass devices with the result that the datasheet stipulates much stricter output conditions for the load. Take care. Ordinary regulators are much more tolerant of the load.
My advice, if you don't need the efficiency of low dropout regs then don't use them.
Hi flyboi
Consider that any class B or AB amplifier tends waste into heat more than 75% of the power drawn from the transformer when playing music signals.
Also, consider that any direct radiating speaker only transfers to the air less than 1% of the power drawn from the amplifier, and the remaining 99% is wasted both as mechanical and electrical heat.
In practice, transformer efficiency tends to be well above 90% so who cares?
If you want a power efficient system, go for class-D amplification with 95% efficiency, and horn-loaded speakers with 10% to 60% efficiency figures.
You can't imagine how loud a bare dozen of watts being drawn from the power supply can sound with such a system. For example, the midrange horn shown in that picture is capable of transferring to the air almost 40% of amplifier power within its frequency range, and the tweeter transfers almost 20% : http://eva.eslamejor.com/mid_hi0.jpg
In comparison, the typical 88dB/W bookself speaker only transfers 0.4% of amplifier power to the air.
Consider that any class B or AB amplifier tends waste into heat more than 75% of the power drawn from the transformer when playing music signals.
Also, consider that any direct radiating speaker only transfers to the air less than 1% of the power drawn from the amplifier, and the remaining 99% is wasted both as mechanical and electrical heat.
In practice, transformer efficiency tends to be well above 90% so who cares?
If you want a power efficient system, go for class-D amplification with 95% efficiency, and horn-loaded speakers with 10% to 60% efficiency figures.
You can't imagine how loud a bare dozen of watts being drawn from the power supply can sound with such a system. For example, the midrange horn shown in that picture is capable of transferring to the air almost 40% of amplifier power within its frequency range, and the tweeter transfers almost 20% : http://eva.eslamejor.com/mid_hi0.jpg
In comparison, the typical 88dB/W bookself speaker only transfers 0.4% of amplifier power to the air.
Andrew, in this application the LT1085 will work fine. The linear PS is not driving an analog audio circuit, but will be powering a Squeezebox which will be feeding only its digital out into my D/A converter. The power draw characteristics of the SB are very stable, and the load is not especially reactive. The 1085 has (so far) proven itself well suited for this purpose. A lot of diy'ing to date is suggesting that getting a really good linear PS feeding the SB makes a significant improvement to its sound. I figured I'd give it a shot.
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