RF T30001bd Clamped

[donpisto 5,000+ posts]

So I decided since I got a good DMM (Fluke, used to have Walmart brand and gave very inaccurate readings) I'd get my T30001bd clamped.

First off, I have an Odyssey PC 1200 under the hood and only 2 of the big 3 done. The wire from the battery positive to the alternator came off and I haven't had the time to replace it. I have a 160A alt that was tested to put out 167A and I believe its doing about 100A or so at idle. So as you can see, it is clearly not enough for this amp. I have an Odyssey PC 2150 that I will have in the trunk, but won't be putting in until I get my new setup going.

Thus said here are the results:

- Amp pulled 184A

- Voltage was 11.4V

- Subs were wired at 1.33 ohms

- Gain set halfway

- Total output power = 2,097.6 watts

Subs I'm running are 3 10" Focal 27A in a 3 cu. ft. enclosure tuned to I believe its 33 Hz. Subs are rated at 250w rms and 500w peak and giving them quite a bit more than their peak rating and they take em fine, don't get stinky at all, and sound quite d*mn good as well.

I will have updates once I get my next setup in. I'll be running at 1 ohm and this time gain will be turned up some more.

Click to read more...

 

[xtremebassjunky 10+ year member]

hmm...

interesting results. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

now lets see it when you got the 2150 wired up as well.

 

[IgnoreMe 5,000+ posts]

So I decided since I got a good DMM (Fluke, used to have Walmart brand and gave very inaccurate readings) I'd get my T30001bd clamped.
First off, I have an Odyssey PC 1200 under the hood and only 2 of the big 3 done. The wire from the battery positive to the alternator came off and I haven't had the time to replace it. I have a 160A alt that was tested to put out 167A and I believe its doing about 100A or so at idle. So as you can see, it is clearly not enough for this amp. I have an Odyssey PC 2150 that I will have in the trunk, but won't be putting in until I get my new setup going.

Thus said here are the results:

- Amp pulled 184A

- Voltage was 11.4V

- Subs were wired at 1.33 ohms

- Gain set halfway

- Total output power = 2,097.6 watts

Subs I'm running are 3 10" Focal 27A in a 3 cu. ft. enclosure tuned to I believe its 33 Hz. Subs are rated at 250w rms and 500w peak and giving them quite a bit more than their peak rating and they take em fine, don't get stinky at all, and sound quite d*mn good as well.

I will have updates once I get my next setup in. I'll be running at 1 ohm and this time gain will be turned up some more.

you made a mistake...

and i know exactly what it is....why? because i made the same one when i was still somewhat new to car audio and got my *** chewed out by immacomputer (glad he did it though, even though i was too pissed off to admit it).

you do not measure battery voltage, and then amperage up underneath the hood. you need to do it at the amp. for example, stick 1 dmm lead into the positive speaker terminal and one on the negative speaker terminal. then place the clamp around the speaker wire going to the subs. get a voltage and an amperage reading at the same exact time.

multiply them to get wattage.

divide voltage by amperage to get impedance.

as you can see, using ohms law you are sitting at .06 ohms, even though you're wired up to 1.33 ohms.

this would mean you are getting ~2kw @ .06 ohms out of an amp thats suppose to do 3k+ @ 1 ohm. see what i mean? easy to see the problem now, i hope //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif.

BTW: even doing it the way i mentioned above will still give you "apparent power" and not real world power. however, the closer you are to the DCR, the more accurate results. what im getting at is, if you wired to a 1 ohm load, and are getting 4 ohms as your lowest impedance after box rise, your power calculation is going to be a good bit off and not very accurate. however if you're wired @ 1 ohm and rise to say 1.5 you are a good bit more accurate. remember the closer to DCR, the more accurate the results. its the same reason you see guys with 2.5kw @ 1 ohm amps, clamping and then calculating out 2kw @ 4 ohms. this is apparent power, and not what the sub is actually seeing. you can calculate it all out using some kind of math (ask immacomputer, i just saw a thread explaining out to calculate power factor and all that good stuff) and a "power triangle" (IIRC thats what he called it)

 

[audioarsonal 10+ year member]

You would need a second to DMM to clamp and take ACV correct?At least my DMM can't read both at the same time.The way he checked it was on the battery side so after effenciy those numbers would be squewed if I'm not mistaken?

 

[donpisto 5,000+ posts]

Quick response George, I didn't get to read all of your post, just a quick portion of it since I'm about to head out to work. Just wanted to point out voltage was taken at the amplifier and from under the hood. I caught a glimpse of what you're mentioning and it sounds interesting to see what I goofed up. I don't mind making mistakes, long as I learn and thanks for pointing it out. I'll probably be posting back in about an hour or so once I have the chance to fully read what you posted.

What I did was (with the help of a friend), I had 2 DMM's. One was clamped around the amps ground wire (close to the amp, maybe 6" away). It was set in amperes as well. I had a second DMM on the ground and power on the amp.

 

[audioarsonal 10+ year member]

That's the problem.You need to read the ACV from the speaker leads as well as the amp draw on the speaker wire(only one) at the same time.This will give you a more accurate reading as to watts and impeadance rise.

 

[donpisto 5,000+ posts]

I'm a tad confused still, rather just wanting to make sure I'm understanding correctly.

The DMM I have will not measure amperes and voltage at the same time, so I must use two DMM's. Doing so, is this how it would be done?

Get one DMM, put the positive leave to the positive speaker terminal, negative lead to the negative on the terminal and then put the clamp around the speaker for the subs. Now I can get amperage or voltage by doing this, say I go with amperage. So with voltage, do I get a second DMM and do the same thing? Put positive lead to positive speaker terminal, negative lead to negative speaker terminal and measure put the clamp around the speaker wire and measure voltage?

 

[xtremebassjunky 10+ year member]

good catch george...

I didn't catch that... but I was skimming through it... //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[IgnoreMe 5,000+ posts]

I'm a tad confused still, rather just wanting to make sure I'm understanding correctly.
The DMM I have will not measure amperes and voltage at the same time, so I must use two DMM's. Doing so, is this how it would be done?

Get one DMM, put the positive leave to the positive speaker terminal, negative lead to the negative on the terminal and then put the clamp around the speaker for the subs. Now I can get amperage or voltage by doing this, say I go with amperage. So with voltage, do I get a second DMM and do the same thing? Put positive lead to positive speaker terminal, negative lead to negative speaker terminal and measure put the clamp around the speaker wire and measure voltage?

//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif you got it. when i did this i made the same mistake, but at least you were in the right area...i was underneath the hood haha

 

[donpisto 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif you got it. when i did this i made the same mistake, but at least you were in the right area...i was underneath the hood haha

How fast did you have to run? lol. Does it matter what the subs are wired at, like in my situation they are wired at 1.33? or would it be better to clamp when i have a 1 ohm load?

 

[xtremebassjunky 10+ year member]

whats the load after rise?

 

[IgnoreMe 5,000+ posts]

How fast did you have to run? lol. Does it matter what the subs are wired at, like in my situation they are wired at 1.33? or would it be better to clamp when i have a 1 ohm load?

i had my buddies under the hood. he checked battery voltage and amperage right up front. this gave me the wattage i was drawing, but it was all before the amp which didnt mean anything in terms of what the amp was putting out.

it doesnt really matter what you're wired at. what does matter is how far away you are from the DCR when you test. the farther you are from DCR, the more skewed the numbers will be because of "apparent power"

for example, if you are at a 1 ohm load, try to find a freq that is as close to 1 ohm as possible. hopefully you got or can make a test tone CD, and just run a bunch of freq, gathering V and A for each freq, and then do the math to see which one is closest to your DCR (ie, which one has the least impedance rise). you should be able to do this on low or medium power to see which freq, will work best, and then when you're ready you can max out the tested freq to get the numbers for the wattage calculation.

 

[donpisto 5,000+ posts]

Don't know, didnt get that measured, or at least I don't know because i was in control of the volume while my friend was in the back doing the measuring.

 

[donpisto 5,000+ posts]

i had my buddies under the hood. he checked battery voltage and amperage right up front. this gave me the wattage i was drawing, but it was all before the amp which didnt mean anything in terms of what the amp was putting out.
it doesnt really matter what you're wired at. what does matter is how far away you are from the DCR when you test. the farther you are from DCR, the more skewed the numbers will be because of "apparent power"

for example, if you are at a 1 ohm load, try to find a freq that is as close to 1 ohm as possible. hopefully you got or can make a test tone CD, and just run a bunch of freq, gathering V and A for each freq, and then do the math to see which one is closest to your DCR (ie, which one has the least impedance rise). you should be able to do this on low or medium power to see which freq, will work best, and then when you're ready you can max out the tested freq to get the numbers for the wattage calculation.

Ah, gotcha, i was using a 60 Hz tone. My friend will be out of town for the following week and lives about an hour away. I'll just wait till i get the new setup in since I'm going to sell the subs I have now sometime text week. Might give me a reason to run 4 eD 8's //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif or possibly 6 of them //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif. I'm selling 4 of em for $60, lol.

 

[IgnoreMe 5,000+ posts]

Ah, gotcha, i was using a 60 Hz tone. My friend will be out of town for the following week and lives about an hour away. I'll just wait till i get the new setup in since I'm going to sell the subs I have now sometime text week. Might give me a reason to run 4 eD 8's //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif or possibly 6 of them //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif. I'm selling 4 of em for $60, lol.

good shit. i really want to see the next test //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif also dont forget to get us some voltage figures at the power/ground inputs on the amp (have them on the first post, but if 60hz happens to be within the impedance spike, another freq should draw a different amount of current). XXXX amount of watts is impressive, but XXXX amount of watts @ 11V is even more.

i have no doubts that amp will put out gobs of power.