Portable oscilloscopes

[captainobvious]

You might also consider getting one or two of these braking resistors to make a voltage divider for testing amplifier outputs


PS...I ordered the 4-pack that he sells, only to find out that I would have saved $20 by ordering them individually

That's WAY easier than trying to build a resistor load bank. Thanks for the heads up Al

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BTW- Why a four pack? Do you need to actually load all 4 channels at the same time to get an accurate reading on a 4 channel amp?

[Fricasseekid]

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BTW- Why a four pack? Do you need to actually load all 4 channels at the same time to get an accurate reading on a 4 channel amp?

Ooh! Good kweshun!



Sent from my Springfield XD with love!

[BigAl205]

What if you want to test it on a 1-ohm load, how would you do it? If the amp has a single power supply, loading all the channels might affect the reading. Also, if it's extremely high power, you might want to run the resistors series-parallel to dissipate the power across them.

Maybe Chad could chime in on this.

[chad]

I use bigass dales, I have them hanging over my bench.... I had another rig that was fan cooled. And the mother of all loads was modified water heater, radiator, water pump, and radiator fan.

But that was for testing some big fucking amps....

FWIW, liquid cooling resistors in ATF works great.... Heath made a RF load called the cantenna.... I use one as my RF load but have cooled big hollow ceramics equally well.

[captainobvious]

I use bigass dales, I have them hanging over my bench.... I had another rig that was fan cooled. And the mother of all loads was modified water heater, radiator, water pump, and radiator fan.

But that was for testing some big fucking amps....

FWIW, liquid cooling resistors in ATF works great.... Heath made a RF load called the cantenna.... I use one as my RF load but have cooled big hollow ceramics equally well.

Chad, can you comment on the single vs all channels question? If you have a multi-channel amp, are you required to load all channels in order to get the proper voltage output at each individual channel, or can you simply load each channel one at a time?

Thanks

[chad]

If you are measuring for max power and want to be accurate then you load them all. However, keep in mind that on say, a 4 channel amp you may have 2 channels running tweets and 2 running midbass so overall output per channel pairs could be quite different in the real world.

Also keep in mind that music is not a 100% duty cycle sine wave. Pro audio manufacturers are adopting new power ratings standards one by one that depict actual output for music uses. like EIA "33/66"

[Fricasseekid]

Can you explain the EIA ratings to me?


Sent from my Springfield XD with love!

[chad]

X amount of time at WFO, X amount of time off.... 33mS and 66mS respectively for the 33/66

But there are many different "EIA ratings"

[cajunner]

anyone likes the CEA 2010 specs for subwoofer distortion?

was reading about that a couple days ago, looks like a graphical representation of an audible distortion curve threshold, I guess some manufacturers won't like it too much...


the way I understand it, is there's a musical representation of a note, which is better than test tones.


it sounds like an advancing method, because test tones and music are so different that this new test would reveal more about a speaker's non-linearity relating to real world conditions in comparison to the old way.

I think they said it was a 6.5 cycles long, test impulse.

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okay, that's off topic for 'scopes, disregard...