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Propeller Head Plaza: RE: Amplifier power meter? by psn Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Amplifier power meter? posted by Mike K on June 30, 2020 at 11:14:31:
Get a bare meter
Look up its reference current (the max current to present full scale deflection (FSD))
Determine its connection polarity (so it does not move the wrong way)
Use a terminal strip with screw connections
Use resistor (appropriate for your amp's power)
Use a diode oriented so it prevents the signal polarity from driving the meter backwardsExperiment with very low power while confirming that only the unblocked polarity of the signal through the diode drives the meter in the full scale deflection direction.
Experiment with resistor values or do the math with the FSD current in mind - gradually increasing power
Use smart phone SPL measure and rated speaker sensitivity to approximate amp power output against meter deflection - adjust amp volume and resistor until deflection registration on face is near FSD at very loud or rated power - if printed scale figures don't match calculated power levels, print your own meter face scale or just live with it
Make copy for other channel
*** Cautions***Start off with large value resistors and work down
The meters I used were scaled for 250W at "full 0dB" with the red zone extending to 300W, but they had a secondary scale maxing to 30W with 1W about dead center... that was the useful scale for my amp
I connected my meters to the "B" set of speaker outputs (so they were in parallel with the "A" set of main speakers), and set the speaker selection to "A+B" when I wanted to view the meterNo guarantees that you won't find a fire extinguisher to come in handy :)
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Topic - Amplifier power meter? - Mike K 11:14:31 06/30/20 ( 23)
- RE: Amplifier power meter? - ytb402 09:57:58 08/23/23 ( 0)
RE: Amplifier power meter? - ytb402 22:37:29 08/21/23 ( 0)
RE: Amplifier power meter? - gberchin 13:07:06 03/22/22 ( 0)
RE: Amplifier power meter? - psn 01/19/22 17:50:45 01/19/22 ( 0)
RE: Amplifier power meter? - andyr 00:32:15 02/20/21 ( 0)
RE: Amplifier power meter? - pictureguy 12:06:14 10/2/20 ( 3)
- RE: Amplifier power meter? - John Elison 15:10:49 10/4/20 ( 2)
- RE: Amplifier power meter? - pictureguy 16:47:02 10/4/20 ( 1)
- RE: Amplifier power meter? - John Elison 20:08:37 10/5/20 ( 0)
RE: Amplifier power meter? - LtMandella 21:21:44 09/7/20 ( 1)
- RE: Amplifier power meter? - pictureguy 21:32:27 09/8/20 ( 0)
RE: Amplifier power meter? - pictureguy 15:16:42 07/23/20 ( 0)
Might need a driver board and DIY skills as well... - Jonesy 14:57:10 07/7/20 ( 2)
- RE: Might need a driver board and DIY skills as well... - Mike K 15:01:07 07/18/20 ( 1)
- LOL! I'm getting tons of VU meter ads now in my browser... - Jonesy 15:30:49 07/18/20 ( 0)
I remember Radio Shack used to sell them... - Jonesy 13:47:21 07/7/20 ( 0)
RE: Amplifier power meter? - 13th Duke of Wymbourne 17:09:23 06/30/20 ( 6)
- RE: Amplifier power meter? - Ugly 11:27:12 02/19/21 ( 0)
Thanks for the reply - Mike K 08:03:13 07/3/20 ( 4)
- RE: Thanks for the reply - pictureguy 18:49:47 09/2/20 ( 3)
- RE: Thanks for the reply - John Elison 23:38:15 09/2/20 ( 2)
- RE: Thanks for the reply - pictureguy 00:03:24 09/3/20 ( 1)
- RE: Thanks for the reply - John Elison 10:16:43 09/3/20 ( 0)