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Discussion Starter #1
I am about to install a PG Tantrum 1200.1 (Class D amp) and want to set the gains using oscillocope/DMM. From what I have read most everyone sets the gains with the speakers unhooked. The 1200.1 manual says that it should never be powered on without speakers connected. None of the other Tantrum (400.4, 600.4, 500.2) manuals say this. So I am wondering is this specific to the 1200.1 and what could possibly happen if I do set the gains without the speakers hooked up?
If I had to I could buy some sort of cheap dummy load to connect the amp to while I set the gains. And to that end, I have some stock 6x9's that I took out and will never be used and are 4 ohm. What would happen if I connected these as my load while setting the gains besides they would never work again?
 

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Discussion Starter #2
Ok so found out this is most likely due to the fact that the 1200.1 model used the tripath chip and the others didn't. The company who made these chips for PG is no longer around and apparently these chips are fairly hard to find. That being said, looks like I will be needing to put a load on this amp to ensure the chips safety. So any suggestions on how big a dummy load I would need to use? The amp does 1200 RMS @ 4ohm so would 1- 8 ohm 300 watt be sufficient since I won't will only have power to it for a short time? And by sufficient I mean not get scalding hot or anything like that in the short amount of time I would need to set the gains.
 

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i would just set the gains by ear...
 

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I also think that setting the gains by ear is the way to go.
 

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Yeah, I know most people are proponents of the ear method but I have two reasons I am trying to use the o-scope/DMM;
1. Just bought one and want to play with it.
2. My two subs are rated to handle 900 RMS combined. So my plan was to use voltage readings to set gain so that the typical max the speakers would see is roughly 900 RMS and still have some headroom.

I am upgrading from a 500 watt amp to 1200 and just trying to make sure I am giving them their rated and not giving too much juice.
 

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I think o-scopes are one of the absolute least important tools in the car audio toolbox. I think setting gains with them is silly, and I think setting subwoofer gains with one is just a complete waste. This of course is my opinion, and since you already bought one you might as well play with it to learn, but I can say with confidence that it won't make your system sound any better than if you set the gain by ear (assuming you don't severly clip the signal, or leave the gains too low to use the power).
 

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Discussion Starter #7
Just in case anyone is curious, I decided to buy one of these to use as my dummy load.
1000W 2 4 8 16 Ohm Aluminium Shell Braking Resistor Resistance Dummy Load Audio | eBay

It's the easiest and cheapest solution I found. Could have bought these tube resistors but those would have cost more and required mounting and wiring but probably are better quality.
4 Ohm 120W Power Resistor | MPJA.COM

I am hoping that since I am not going to be sending this thing continuous power very long that it will suffice.
 

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It was recommended to me when using a scope to set gains on sub amp to use a -10db test tone.

If you set it with a 0db tone you will find yourself very low on the gain and will probably then want it set by ear, which for me is into some distortion, not absolutely free of it.
 

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It was recommended to me when using a scope to set gains on sub amp to use a -10db test tone.

If you set it with a 0db tone you will find yourself very low on the gain and will probably then want it set by ear, which for me is into some distortion, not absolutely free of it.
I used to use -6 dB then adjust by ear after that.
 

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Well at least your not spending 40-60 bucks on wire wound resistors...lol. You went straight to CHINA's supply, there's no data sheets for those resistors your purchasing or consider purchasing which just leads me to believe they are not built to ANY SPEC or have any QC what so ever. So be careful and check the dummy load to make sure its the correct resistance..also check it after testing to see the if the value changed (it will a bit).
 

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Well at least your not spending 40-60 bucks on wire wound resistors...lol. You went straight to CHINA's supply, there's no data sheets for those resistors your purchasing or consider purchasing which just leads me to believe they are not built to ANY SPEC or have any QC what so ever. So be careful and check the dummy load to make sure its the correct resistance..also check it after testing to see the if the value changed (it will a bit).
The amazon listing has some specs and testing details listed below once you are in the actual listing. I am a little leery of them just because they are a good bit cheaper than what I can find elsewhere and are "rated" for 1000 watts. I'll be sure to measure resistance when I get them.
 
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