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The bike was not running... How much difference would that make. I'm trying to do everything right.
When I was setting the amp gains, I tried it with the bike OFF. The reading would drop, as the battery voltage went down. I finally got it set at the JL Audio recommended 23.7 VAC. While I didn't measure the battery voltage at that point, I'm sure it was around 12 VDC.
At the advice of the Forum Audio Brotherhood (FAB), I started my bike, let it run for 7-8 minutes, then rechecked the gains with the bike idling. The VAC was steady as a rock, but my initial settings (with the bike OFF) had put the voltage at 32 VAC, a sure way to melt something. The difference is that when the bike is running and the voltage regulator is in play, the electrical system is getting a constant voltage of 13.8 +/- VDC.
Always set your gains with the bike warmed-up and idling.
Originally Posted by hypecat
Tailwind,
So you think an 11 o'clock setting would be OK? I am pretty sure that would be about 25 volts. I know at 2 o'clock it's pushing almost 40 volts.
Do you think the 23.7 is a "safe" recommendation from JL?
I am driving Arc Moto 602's.
JL's recommended setting of 23.7 VAC is based on the formula we all use: The square root of (watts x ohms), which in the case of the MHX is the square root of (140 x 4) = 23.66 VAC.
This amp is "under-rated" and can be pushed a little harder, say 25 to 25.5 VAC without any ill affects. I think Tailwind was running his much higher when it vaporized. LOL
You have a DMM, so use it. Don't worry about the gains being set at half-passed eleven or other such "visual" settings. The pots from one amp to another can vary by one or two hours (clock reference).
I ran my 280/4 at about 26.5 volts (175ish watts) to a set of M770's without issue. I actually had a local shop set up the amp initially and they had it pushing 27 volts but I backed it down a tad just to be safe
The Moto 602's like power and I think sound better with 150+, I'm running a TM400x2 to a set of 602's right now and love the sound.
I'd start at between 25 and 25.5 to the 602's and move up WITH THE BIKE RUNNING.
If you want to play it safe, don't go past 26.1 volts (I had a clean signal a tad over 27 volts, yeah I checked ) but if you don't have a way to check if the signal is clean or not (o-scope or DD-1 etc) then probably best to stay below 25.3 just to be safe.
I checked my voltage with the bike off, turned on to ACC and plugged into a battery tender. (I'm in Minnesota, the bike is still on the jack for the winter).
So, if the bike were running, it sounds like the voltage would actually read higher at my current sensitivity settings?
I checked my voltage with the bike off, turned on to ACC and plugged into a battery tender. (I'm in Minnesota, the bike is still on the jack for the winter).
So, if the bike were running, it sounds like the voltage would actually read higher at my current sensitivity settings?
Short Answer: YES
Long Answer:
With your bike on the battery tender, check your DC voltage at the positive & negative post on your amp, with the sound system "OFF" and then with the sound system "ON.
Depending on the specific battery tender you're using and it's rated output, you may not see the 13.8 VDC that occurs when your bike is running or the VDC could be higher.
With the bike on the battery tender & sound system "ON" , setting the gains to 23.7 VAC will be too high, when the bike is running. 23.7 could go up to 28 (for example) and things would start to heat-up in the amp.
Setting the gains with the bike running assures that they set with your bike's actually charging system output.
If you want to play it safe, don't go past 26.1 volts (I had a clean signal a tad over 27 volts, yeah I checked ) but if you don't have a way to check if the signal is clean or not (o-scope or DD-1 etc) then probably best to stay below 25.3 just to be safe.
Another great point, Bunker. If you don't have a way to check the quality of the input signal, you're treading on thin ice when you push the voltage beyond specification.
It's the old "Garbage In = Loud Garbage Out = Call the Fire Department because my bike's on FIRE" scenario.
With your bike on the battery tender, check your DC voltage at the positive & negative post on your amp, with the sound system "OFF" and then with the sound system "ON.
Depending on the specific battery tender you're using and it's rated output, you may not see the 13.8 VDC that occurs when your bike is running or the VDC could be higher.
With the bike on the battery tender & sound system "ON" , setting the gains to 23.7 VAC will be too high, when the bike is running. 23.7 could go up to 28 (for example) and things would start to heat-up in the amp.
Setting the gains with the bike running assures that they set with your bike's actually charging system output.
Yes, I need to readjust with the bike running, there is no doubt. Thinking about shooting for 25 to 25.5 per your and Bunker's posts.
24.5 to 25 vac seems to be a good spot so 150 - 156 w is working well with the AWs. I did burn one amp up running quite a bit higher than that with a big load so I'm still trying to find the outside edge of the sandbox with the AW load. Ironically the DD1 shows clean power pretty damn high but the workload seems to be the only concern.
T.
Thanks for the heads up T.
Apparently the thermal overload protection didn't kick in.
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