I would like a digital panel meter attached to my bench that displays watts produced by amplifier being tested. I can't find anything where the load is programmable for 2/4/8 ohm load except this:
https://www.velleman.eu/products/view/?id=381888
Otherwise the meters I've seen use a clamp to measure current...that's not what I want.
Is this too much to ask?
https://www.velleman.eu/products/view/?id=381888
Otherwise the meters I've seen use a clamp to measure current...that's not what I want.
Is this too much to ask?
Buy PZEM-020 10A AC Digital Display Power Monitor
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The velleman.eu link says it's out of stock. Jameco has it on ebay; Velleman K8098 Audio Analyzer Kit with White LCD | eBay There's a Gen-Rad device that you wont be getting for $75; it's only good to 20 watts - GR1840A. That's more like a benchtop unit.
What you are after is a meter calibrated in watts for each of the three impedances. In an earlier era you would have made a simple rectifier/filter to make DC from the ayudio and then hand calibrate an analog meter with the appropriate numbers. a 20 dB attenuator could extend its range. There have been similar in the past and you may find something from Radio Shack or Lafayette on eBay. I would not expect anything but I did see this: REALISTIC APM-500 AUDIO POWER METER 2 OR 200 WATT RANGE LED VU METER VINTAGE | eBay . I used to have one.
I think the meter on the HP8903 is calibrated in watts as well.
I think the meter on the HP8903 is calibrated in watts as well.
Try something like this
An externally hosted image should be here but it was not working when we last tested it.
Current output is total current - quiescent current, or idle current, amplifier consumption, whatever you care to call it.
This can be connected at input, and used.
He can check at different frequencies.
This is a much simpler way to achieve his result compared to an audio analyzer, and maybe a little more versatile for different purposes.
This can be connected at input, and used.
He can check at different frequencies.
This is a much simpler way to achieve his result compared to an audio analyzer, and maybe a little more versatile for different purposes.
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Heathkit had that. I thot it was in a distortion meter but I see it was (also?) a standalone.
https://www.w6ze.org/Heathkit/Heathkit_088_AW1.pdf
Needle-meters make it easy because you "multiply" just by numbering the scale. The vacuum tube is not essential over say 1 Watt @ 8 Ohms (sub-Volt signals run into diode errors). Digital may be a LOT more work, unless you program PICs for fun/money.
IM meter: https://www.rsp-italy.it/Electronics/Kits/_contents/Heathkit/Kits/Heathkit IM-48 audio analyzer.pdf
Audio Wattmeter AW-1U Equipment Heathkit UK by Daystrom, bui
https://www.w6ze.org/Heathkit/Heathkit_088_AW1.pdf
Needle-meters make it easy because you "multiply" just by numbering the scale. The vacuum tube is not essential over say 1 Watt @ 8 Ohms (sub-Volt signals run into diode errors). Digital may be a LOT more work, unless you program PICs for fun/money.
IM meter: https://www.rsp-italy.it/Electronics/Kits/_contents/Heathkit/Kits/Heathkit IM-48 audio analyzer.pdf
Audio Wattmeter AW-1U Equipment Heathkit UK by Daystrom, bui
Actually ANY voltmeter could do that, if you cal the scale in Watts.
We used to take a voltmeter, open it up and replace the scale by a new one calibrated in Watts; there would be three scales for 2, 4, 8ohms.
There is even free software online that helps you set up a scale and print it and you can glue that to the meter dial.
Custom Meter Scales
Works like a champ. I used it to make 10kV voltmeters, but the series R is a b*** ;-)
Jan
We used to take a voltmeter, open it up and replace the scale by a new one calibrated in Watts; there would be three scales for 2, 4, 8ohms.
There is even free software online that helps you set up a scale and print it and you can glue that to the meter dial.
Custom Meter Scales
Works like a champ. I used it to make 10kV voltmeters, but the series R is a b*** ;-)
Jan
The big meter is connected to the input, the supply passes through that, and the one we have has capacity of 10A @ 220 V = 2.2 kW.
Enough I think for most work.
You see the current or power draw at idle, that means zero signal, zero volume, that is the amp only power consumption.
Crank it up to full, and full input signal, that will give you the power drawn by it at full load.
From this subtract the idle level power, that will give you the output power on all channels.
There must be a load on the unit.
Repeat with different frequencies if you feel like.
There are no kHz involved, this is telling you the system input from mains.
If you try this on output side, the multiple frequencies and relative emphasis will not be easy to calculate.
This is a quick and reasonably accurate, and repeatable system.
Enough I think for most work.
You see the current or power draw at idle, that means zero signal, zero volume, that is the amp only power consumption.
Crank it up to full, and full input signal, that will give you the power drawn by it at full load.
From this subtract the idle level power, that will give you the output power on all channels.
There must be a load on the unit.
Repeat with different frequencies if you feel like.
There are no kHz involved, this is telling you the system input from mains.
If you try this on output side, the multiple frequencies and relative emphasis will not be easy to calculate.
This is a quick and reasonably accurate, and repeatable system.
Maybe you can connect a Schottky bridge to output, and measure DC V and Amps, and get watts.
I do think a short circuit might occur...
Can even use a mains power meter, the single phase electronic kind, even those give you the same set of readings...essentially a current / voltage sensor, and a special IC...and LCD.
Maxim and Hitachi made those chips.
I would not take the trouble for $30...
I do think a short circuit might occur...
Can even use a mains power meter, the single phase electronic kind, even those give you the same set of readings...essentially a current / voltage sensor, and a special IC...and LCD.
Maxim and Hitachi made those chips.
I would not take the trouble for $30...
HTC Instrument PM-01 Power Monitor 10A : Amazon.in: Industrial & Scientific
Ir is good to 10A / 220V
Ir is good to 10A / 220V
No audio amplifier has constant internal power.
In class A the total input power should be constant, the output power deducts from that, so this technique is useless.
In class B the input power rises with signal and output. The trend is clear but in many amps not linear or monotonic.
Class D it almost works, but the load-related losses are not zero.
Anyway these meters are made for 220V. (Typical tube-amp speaker voltage is 3V to 30V.) I use one on 125V and am already losing accuracy. Also they take working power from the circuit being measured. If you do not have dozens of Volts they quit working. Get one and try it. (BTW, a large part of their demand is the LED.) Same for the "car battery meters", they quit below 7V (I had one punk-out at 11V).