Amp Benching?

[CrazyKenKid 10+ year member]

Hey guys i am looking to get about 3 amps bench tested but I have no idea where to take them? Can anyone help me out?

The amps i want to get benched are a kicker sx650.1, zapco i600, and elcipse 7122a!

SO if anyone has done this before let me know where you went and your over all experience and of course how much it costed, and how long it took!

thanks

Kenneth

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[Pioneer~Saturn 5,000+ posts]

You can get a clamp multimeter and take readings of the speaker outputs and do the math for wattage...if that's what youre looking to find

 

[CrazyKenKid 10+ year member]

actually i guess i am looking to get a birthsheet that say this amp will due a max of XXX rms at Xohm

I guess i want to make it office that way when i got to sell those amps the sheet may catch someones eye or something...does that makes sense?

 

[Pioneer~Saturn 5,000+ posts]

If youre looking for something official like that then im not too sure..

 

[CrazyKenKid 10+ year member]

You can get a clamp multimeter and take readings of the speaker outputs and do the math for wattage...if that's what youre looking to find

quick questions how do i attach the clamp multi meter to the speaker? just put the clamp around the positive wire leading to the sub? and then how would i do the math? sorry i am noob at doing stuff like this!

 

[CrazyKenKid 10+ year member]

bump bump anyone?

i have been asking some ppl and they recommened audio repair places!

 

[CrazyKenKid 10+ year member]

Bump bump for a birthsheet on my amp(s)?

 

[gunz4me 10+ year member]

Your easiest bet would be to send them to Stephen Mantz at Zed audio! The only downside is that you are in Canada and shipping will be a killer //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

You can do a poor man's bench test with a resistive load, DMM, and oscilloscope but it will only give you a "general" idea. Determining distortion percentages on your own is probably next to impossible.

 

[CrazyKenKid 10+ year member]

Your easiest bet would be to send them to Stephen Mantz at Zed audio! The only downside is that you are in Canada and shipping will be a killer //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif
You can do a poor man's bench test with a resistive load, DMM, and oscilloscope but it will only give you a "general" idea. Determining distortion percentages on your own is probably next to impossible.

do you have a phone number for this guy so i can get a hold of him? i cross over to the states every now and then plus i have an american contact where shipping can go! lol!!

 

[bikinpunk 10+ year member]

Any electronics tech store should easily be able to do this for you. If they have a power supply to run it on, they can test it inside the shop. If not, they can test it in your car.

All you need are some good dummy loads (high wattage resistors) to put a load on your amp (if you use speakers and a test tone to find out max wattage you’ll FRY your speakers). ***you could probably get by without using a dummy load… you could get close enough for your concerns***

Dummy loads are sold at parts express; price varies.

Then use an oscilloscope to see when the signal clips with a 1000hz tone attenuated -3dB. At this point on the gain which the amp is just near clipping, use a multimeter to check the voltage output on the speaker terminals. Do the math and you’ve got your power @ (x) load.

So, all the shop needs to do is:

1. Have an oscilloscope

2. Know how to use it

3. Have a Multimeter

4. Know how ot use it

You’re set.

I purchased an oscope for this exact type of thing, and also to test headunit preout voltage.

Just to give you an idea of the setup for headunit preout voltage, here’s a pic:

http://i18.photobucket.com/albums/b138/bikinpunk/IMG_5413.jpg

You can see in that picture that the headunit is set to volume 35 out of 35 (maxed out). On the oscope you can see a solid sine wave: no clipping. Next to that you can see the DMM hooked up to the RCA preouts of the headunit and reading 4.14v.

An amp test would be really similar, except the oscope’s inputs would be attached to the amplifier speaker outputs on one channel (or 2 if you’re checking for bridged output).

Took me a while to figure it out but with some help from some dudes who know this stuff, I was set up in a few minutes.

 

[CrazyKenKid 10+ year member]

WOW i think i can do this lol! i have an o-scope at school i can borrow plus millions of resistors i alos have access to! and i couldn't view your pic it says bandwitch exceeded

thanks a lot man you rock!

PS could i get you to send me that pic?

 

[CrazyKenKid 10+ year member]

is this what you mean by a dummy load

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=019-030

if so would this work with my elcipse amp with is like 1000 rms at 2ohm on 10volts?

 

[bikinpunk 10+ year member]

that type of dummy load would work, yes. are you wanting to test at 8ohms, though?

Also, keep in mind the kind of power you expect to have. Would 200w be enough? Do you need to buy a couple and wire them in parallel/series? These are things you need to think about. Oh, and those things will get HOT! do not touch!!! Some use their own ways of cooling (oil, water, etc)... you'd have to search on this. google should help.

Now, again, some say that you don’t need to put resistance on the amp; that it’s clipping point is the same no matter the load. I’ve asked about this and was shown proof that the same gain position on an amplifier can clip with one load, and not on another.

This is something I haven’t tried to prove myself, but I have seen the evidence and I believe it.

If you do this at your school make sure the power supply is enough to handle the amp. IOW, I wouldn’t try to rock an amp full tilt on only a 5amp power supply. I use a 55amp PS to power my car, and also for my test bench. It’s probably overkill. Just make sure you don’t use too little.

You’ll probably want help setting up the scope. You should only need to use one lead on a single channel; that lead may need to go only to the positive terminal on that channel, or the negative on that channel. In the case of my PDX’s, I just put the oscope lead to the + of channel 1 and got signal. On channel 2 it had to be put on the – terminal. There’s reasons for this that were explained to me but it was much more than I can regurgitate now.

Just be careful. I’d get someone who knows wtf they’re doing to help you out initially so you don’t fry something. Or at the least, you could easily knock out a circuit in your house. It could very well happen, too. I know. Trust me!

 

[lilmaniac2 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif I usually bench about 2-3kw depending on how I feel that day //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[Haunz 10+ year member]

Determining distortion percentages on your own is probably next to impossible.

I use speaker workshop.