play a 0db sine wave. set everything to flat. measure outputs. when you see the sine wave start to flatten is when its clipping

 

Thanks, Nick. I'm just not sure how to measure the RCA outputs with the probes.

 

no worries. and ah, i see. positive to center pin, negative to outer shield

 

Awesome. Thanks, man!

 

Another way would be to set amp gains to minimum and dial up the HU until the output from the amplifier distorts. Lower the volume until the output clears up and you now have the HUs maximum clean output level. Then you can begin setting the amp gain and you don't need to change how/where the scope is connected.

 

If it has bnc input it’s easier to use a short rca lead and a bnc/phono adaptor, it’s literally a dollar or so and makes it so much easier, they are 70p from a U.K. supplier

 

Great option but he has a Liumy which is like a multimeter but with graphing oscilloscope capability.

Easiest way is like he said - getting a pair of alligator clips and attaching one end to each probe and the other end (preferably) to an old rca plug that has been snipped and wires exposed so the alligator clips can grab onto them.

You can use just the probes too and stick the red probe inside the female RCA while touching the black probe to the outside of the RCA but it can be a bit cumbersome.

The actual test tone used has generally been intriguing to me. I've typically used -5db at 40hz and 1000hz but often see it suggested that you should use 0db or -10db so I just split the difference?

 

Agree about the BNC adapter.Much simpler to use than trying to touch two probes to an RCA plug.

 

In that case I’d make up a lead with a pair of red 4mm bullet connectors with the insulation removed, soldered to a cheaply rca plug, Ive made up many leads for various jobs with an array of ends and leads

 

In that case I’d make up a lead with a pair of red 4mm bullet connectors with the insulation removed, soldered to a cheaply rca plug, Ive made up many leads for various jobs with an array of ends and leads <img src="http://www.diymobileaudio.com/forum/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" />

Yep,I've even thought of buying an extra set of DMM probes and attaching an RCA plug to them.Wouldn't take but 15 minutes and some solder.

 

These came today. Much easier to use on the RCA than the probes! They were perfect for the job.

AST Labs Test Cable Lead High Current w/Small Alligator Clip Banana Plug Right Angle 39" / 1 m

Interesting thing about the Liumy so far is that sometimes the waveform is large, and sometimes it's extremely small.

 

Interesting thing about the Liumy so far is that sometimes the waveform is large, and sometimes it's extremely small.

The up/down arrows can change that and I believe the "select" button does an auto adjustment.