[doober]

Well i imagine at those sort of powers you could probe across the terminals of the sub and across one side of the speaker cable (between the amp and the sub ends). I think the current through the sub would be measurable from the latter and the voltage from the former. ie. Work out what the resistance of the speaker wire segment is too.
Play a nice low test tone and have the two waveforms displayed at the same time, work out where the peak power values are (perhaps the scope has some maths functions) and do root 2 to get an approximate RMS (assuming nice sin wave outputs, which is rather unlikely).

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.
Modified 1986 Series 4 RX-7 Turbo II
Soon to be:
Hertz 2x(HT25, HV100, HV200L) + HS300 (2cf, 35Hz)
Response 5ch amp (3x200W)

[Andu]

And for this i'll have to move the oscilliscope into my car? It doesn't sound like a very straight forward task http://www.caraudioaustralia.com/ubb/smiles/frown.gif

How is there a risk of electrocution from an oscilliscope? i'm not pulling it appart am I? hehe

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Car: '90 Nissan Pintara (sedan)
Headunit: JVC KD-SX750
Fronts: TotalRecoil 6" 2way splits
Frontamp: Alpine MRV-T301
Rears: Pioneer 4" 3way coaxials
Sub: DVC 4ohm 12" Alpine Type-R (ported @ 35Hz)
Subamp: Response 2x150WRMS (extra mosfets & caps, 2ohm mono)
SPL: 137.7db (hoping for 140db+ next time)
"If its not quick, may aswell make it slower"

[Butchman]

I'm interested in modding my amp, but have a couple of questions...
1)Where do i buy the mosfets from in melb??

2)Do i have to take the PCB board completely out of the amp to put the extra parts in?

and

3)Do i need a fine point soldering iron(rather than a normal larger one)??

Thanx in advance

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So Far:-
*Headunit - Panasonic CQ-DF701
*Sub - Cerwin Vega 15" SVC ...<One more nearly on itz way!>
*Splits Amp - Audioline 2x300Watt (AL-2300)...<To be upgraded!>
*Sub Amp - Jaycar 2x150RMS(AA-0434) ...<One More 2 Come Yet!>
Currently On The Hunt For:-
*VN or VP Wagon
*A 2nd Cerwin Vega 15" SVC...*A Second Jaycar 2x150RMS(AA-0434)
*Splits Yet To Be Decided

[shiny_car]

quote:

---

Originally posted by Andu:
How is there a risk of electrocution from an oscilliscope?

---

hee,hee, that's something i read on these very forums! even if it's a myth, i wouldn't take the risk of 'experimenting' unknowingly. http://www.caraudioaustralia.com/ubb/smiles/wink.gif

but i imagine problems could occur if you inappropriately ground the 'scope or something silly like that. http://www.caraudioaustralia.com/ubb/smiles/confused.gif

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

[shiny_car]

i think that's the problem...most manufacturers don't state how they tested their amps. so i'm not sure if they use a 4ohm dummy load or a reactive load like a speaker. but of course the outputs will vary depending on the frequency.

most specs are quoted for outputs at 1kHz. this of course is not representative of driving a sub which is far more difficult than driving a midwoofer/midrange speaker.

so who knows, which is why one should take the specs with a grain of salt, and as cyberpunky always says, judge with your ears and less so with your eyes and the specs. you at least need to be mindful of what the specs can mean in light of the overall design of the amp (eg: is it likely to perform well driving subs).

http://www.caraudioaustralia.com/ubb/smiles/confused.gif

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/////ALPINE audison DYNAUDIO polkaudio OPTIMA Stinger LIGHTNINGAUDIO

[wldwgn]

jeez guys i was expecting a two line answer thanx for all your help you guys rock!

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Team CAA
Team SCR
SCR - Admin

And do you know what even my missus thinks the wagon is WILD



[Edited 1 time by wldwgn on 18 July 2002 at 07:35]