dB Don
Well the finals is over and I felt it was a very good finals despite the lower than average turnout. The show was a success for all formats involved and manufactures.

This finals marked another first in history, the clamping of power every run in the stock and trunk classes. It also marks the first time a single rms watt measurement device has been used in any org. The clamp was put on very quickly and saved a lot of time.

I want to hear the thoughts from competitors who had the pleasure of the clamps in their cars to witness their accuracy compared to the flukes which are known to measure spike power at the beginning of burps, the extech did not measure that spike, making it much more of a true power measurement for us to monitor power.

They worked amazing I just wanted to hear what you guys in the classes thought as well.
Also thanks to Terry for being our first volunteer to play with these in the pit area.
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AudioRoach
Don

What was the model of the clamp you used for the tests?
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audioarsonal
Extech is a division of Greenlee so they make decent equipment. I believe Fluke is still the best meter available. But I also own an Extech which seems to give very close if not identical readings. I just don't use "in-rush" or "max hold".
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Mr.Sears one 15 sub from hell
dB Don wrote:
Well the finals is over and I felt it was a very good finals despite the lower than average turnout. The show was a success for all formats involved and manufactures.

This finals marked another first in history, the clamping of power every run in the stock and trunk classes. It also marks the first time a single rms watt measurement device has been used in any org. The clamp was put on very quickly and saved a lot of time.

I want to hear the thoughts from competitors who had the pleasure of the clamps in their cars to witness their accuracy compared to the flukes which are known to measure spike power at the beginning of burps, the extech did not measure that spike, making it much more of a true power measurement for us to monitor power.

They worked amazing I just wanted to hear what you guys in the classes thought as well.
Also thanks to Terry for being our first volunteer to play with these in the pit area.
Don..this is the only way to do it,good job for stepping up and doing this,also for the people that use the "peak hold" function,if you didn't know,once you get your acv,and aca peak hold values,you divide them by the square root of 2(1.414),them multiply those values to get your true rms wattage. Once again Don,great job man...
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augustijnen Peter
great to see its done the right way
The one and only , back for more !!!!
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murilo
Ok, we have to clarify a few things commented here:

We are measuring VA (apparent power) as we don't consider the phase difference between current and voltage (after resonance the voltage is delayed so a woofer becomes capacitive). That is not a problem, but is important to know that the real power will be lower (affected by the power factor).

By using MAX hold with separate meters, Mr. Sears, you DO NOT need to convert it to RMS values if the meters are already true RMS. The difference here is the the time window the meter takes to acquire data, the power meter being much slower it will measure a "kind of average" power figure because the battery power will quickly drop throughout the burp (voltage drop).

And then I had this idea, if you use a power factor correcting circuit the meter will read real power, and it can be quite lower than the apparent power.
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rbdbdrag
never liked the clamp meter.dont want people knowing what my amp can put out,the people with the money will just go and buy 10 amps like mine and pick the highest one that works for them then sell the rest,.had it happen in all the hobbys thay we have done in the last 40 yrs,used to have a person in rc racing buy electric motors and dyno them pick the best ones and sell the rest,that way u couldnt beat him in a race,
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Mr.Sears one 15 sub from hell
Murilo..yes you are correct,and very knowledgable...I sir,am very knowledgable also...but even a true RMS meter isn't accurate,because you have to factor in frequency response,and crest factor.If you get a true rms acv,and aca meter...they will still read higher than the clamp method Don,is using.
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murilo
Mr.Sears one 15 sub from hell wrote:
Murilo..yes you are correct,and very knowledgable...I sir,am very knowledgable also...but even a true RMS meter isn't accurate,because you have to factor in frequency response,and crest factor.If you get a true rms acv,and aca meter...they will still read higher than the clamp method Don,is using.


Well the frequency isn't a problem on a good true RMS meter, they read well in the audio range and even higher, crest factor is fixed for a since wave, 1.414 while a square wave is 1 and a music varies.

It would read higher if you hit MAX hold, for the reasons I stated on my other comment, because the power meter is very slow and takes a while to acquire data.
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murilo
rbdbdrag wrote:
never liked the clamp meter.dont want people knowing what my amp can put out,the people with the money will just go and buy 10 amps like mine and pick the highest one that works for them then sell the rest,.had it happen in all the hobbys thay we have done in the last 40 yrs,used to have a person in rc racing buy electric motors and dyno them pick the best ones and sell the rest,that way u couldnt beat him in a race,


The easier way then would be buying one and working it's power supply so it's louder. Clamping is the way to go, all we need now is some standards.
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dtbrown
dB Don wrote:
Well the finals is over and I felt it was a very good finals despite the lower than average turnout. The show was a success for all formats involved and manufactures.

This finals marked another first in history, the clamping of power every run in the stock and trunk classes. It also marks the first time a single rms watt measurement device has been used in any org. The clamp was put on very quickly and saved a lot of time.

I want to hear the thoughts from competitors who had the pleasure of the clamps in their cars to witness their accuracy compared to the flukes which are known to measure spike power at the beginning of burps, the extech did not measure that spike, making it much more of a true power measurement for us to monitor power.

They worked amazing I just wanted to hear what you guys in the classes thought as well.
Also thanks to Terry for being our first volunteer to play with these in the pit area.


All the back and forurth about how to read true rms aside I think it was a much welcome part to finals. I have not to expensive Ideal meters and they were with in 50w or so of the finals clamp meters. And that is all that is needed for a competitor to get a good idea where he should be testing at. And once they get to a show ask the judge to clamp them to do a little adjustment and they'll be fine.

To all the people saying that this isn't true rms due to frequency or what not that's not the idea. It a great way to even out the playing field and resolve the issue of what 2000w amps should be allowed in Street Stock. It was great knowing that my power was about the same as the person next to me and I was beat by better design not that the person found an amp rated at 2000w but he was able to squeeze 3000w out of it.

Finals was well run and with the new rules made Street stock a lot of fun and I look forward to competing in it again next year. Great job
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Mr.Sears one 15 sub from hell
murilo@soundigital.com.br wrote:
Clamping is the way to go, all we need now is some standards.
Murilo...I agree 100% with this statement..key word..."standards",and I think Don is on the right path,with that...
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THE-SCRAPER
dB Don wrote:
Well the finals is over and I felt it was a very good finals despite the lower than average turnout. The show was a success for all formats involved and manufactures.

This finals marked another first in history, the clamping of power every run in the stock and trunk classes. It also marks the first time a single rms watt measurement device has been used in any org. The clamp was put on very quickly and saved a lot of time.

I want to hear the thoughts from competitors who had the pleasure of the clamps in their cars to witness their accuracy compared to the flukes which are known to measure spike power at the beginning of burps, the extech did not measure that spike, making it much more of a true power measurement for us to monitor power.

They worked amazing I just wanted to hear what you guys in the classes thought as well.
Also thanks to Terry Brocks for being our first volunteer to play with these in the pit area.


I forgot what type of meter Don used ..... but I have my credit card # ready I'm definitely buying one!!
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HawaiianBassHead
so does he also check impedance or something other than just clamping ac amps on the amplifier outputs? curious his method or does it read voltage as well as amperage? I suppose that would make sense but I think an adjustable regulator on amps OUTPUTS would with built in monitoring in the knob would be killer huh murilo? something worth doing on the newest gen SD amps maybe *raises eyebrows at the SD man* or I suppose guys can just use their bought meters and the volume knob to control output LOL.. sounded like a fun idea
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dB Don
The meter is an Extech 380940 I posted pictures in another thread.
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