static

This is the inside of my JBL px300.4. I have narrowed down the noise in my system (HISS) to the amplifier itself by 1) Using muting plugs 2) Removeing the amp from the vehicle and using a "test bench" if you will and a test speaker to find the same noise. It's a low hiss with the vehicle OFF and ear right up close to speakers. By "test bench" I mean I connected the amp right by my battery with the ground going straight to the battery and used a test speaker and adjusted every setting on the amp with no change - gains at zero - no rca's connected. So I took off the cover not the entire sink case and looked around. Here are the two things odd I found. I'm no expert and if this won't cause noise, I'll just have to live with some minor hiss till I get it repaired or get a new amp.

I sent an email to JBL about this noise/hiss issue and here is the response. I spoke with our engineers regarding this. The hiss that you hear is actually considered normal for this amplifier model.

You have a PM sir.

Well what I mean is the engine is not running, just the key turned to acc. Sorry for the confusion.

Yes it is turning off. Nothing wrong with that. Why do you ask?

I have no idea, that's why I posted the pic. Maybe someone has an idea what could have caused that or if it even matters.

Or maybe someone has some ideas of what to look for inside the amp to help me out. Or maybe, well it has to be the amp only thing that is the same from the test is the vehicle battery. I used different wires, speakers, grounded to the battery, different turn on lead, different head unit. Maybe it's the h/u wire harness? Some wire in there? I did find out after I reinstalled the amp that the noise (HISS) does increase with the gain, but with the gain at minimum there is still noise <-- no rca's connected. I should say when I set my gain with my oscope the hiss does not increase, only when gain is moved to 3/4 to full does the noise increase. But from let's say about 1/2 or 5/8 gain to zero gain the noise is the same level. The Hiss ONLY goes away when I set the filter(s) to low pass on the amp. The Hiss is there in high pass and in flat

How many you got

This is my thinking also. I have an email into a enclosure designer for a underseat build for either a Q10 or 12, ported or sealed. We'll see what he comes up with. I can build enclosures - quite well I might add and fiberglass as well, I'm just not good at the designing part as far as complicated designs go. If anyone has any ideas or designs for a 2002 ford f-150 supercrew for under the seat, let me know. Stupid dumb truck, no room for a subwoofer, now if I could find some bucket seats for the front passanger or rear buckets I'd be in business. Uh inexpensive ones

Ok, I have owned quite a few subs in my quest to find the right one for me. I searched long and hard for a '05 XXX 12 and I finally got one powered by a tantrum 1200.1 in a 1.1 'ish cubic foot enclosure. I think it's suffocating though. It sounds good, I just think this sub was more suited for a larger sealed or ported only enclosure. For my vehicle I can only fit a small sealed enclosure, so I was thinking of going back to a Q12. I have a SSD12 with copper coils/BP but it's in my home theatre setup right now. Should I keep the XXX, because it is an awesome sub or go with a equally awesome sub the Q12 because it's better suited for my application? The vehicle is a 2002 supercrew - limited space without something creative or extreme measures like taking out a seat Thoughts, Comments?

Hmmm... Sell the SSD, buy the Q for vehicle and put XXX in the 2.2 ported enclosure in the house? Not a bad idea, except the XXX is dual 4 and my plate amp will only do 4 or 8 ohms and it's not much power at 8 ohm either. But not much power is needed in the home theatre dept. as opposed to car audio.

ugh, why can't I access the new site Internet Explorer cannot display the webpage

But other than the ass the rest of it is great

I keep all original packaging just for that reason. The Mag I currently have was sent to me in a less than perfect shipping container. This was purchased from someone on another forum, this is how it came. I honestly don't know how it survived. It was a miracle. I literally reached my hand into the hole and pulled out a subwoofer. Sorry to jack your thread with this packing nightmare

That Mag's ass looks a lot like the current one I have that also got damaged in shipping

Yea, where are you located?

Please don't mess with the gain settings, if you didn't and the installer set it up this way shame on him/them and you should go back there and get an explination. The install is jacked!!!!

1) subs are in wrong enclosure alignment - should be ported 2) subs are probably wired correctly for amp being used. - which is 4 ohms 3) at 4 ohms that memphis amp puts out 250 watts total - 125 watts to each sub 4) if you disconnect one sub the other will recieve 500 watts at 2 ohms if wire up correctly - I don't suggest you do this because of the lack of experience I sense here. Plus if enclosure is shared chamber that single sub will see 500 watts in 1.7'ish cubes. Not good if you don't know what you are doing.

And I thought you told them to build you a ported box? Sounds like a great installer, I'm sure you paid for a ported box. Assassins, as stated by the sub designer and manufacture says that these subs work in small ported enclosures.

Of course the installer says no way it's his fault. Wiring = ? To me that wiring of the subs does not sound right at all. The subs are dual 4, so two of them = wired to 1 ohm or 4 ohms. Memphis 500/1 = not 1 ohm stable. So I'm sure the shop that sold you the amp knew that so they wouldn't wire it to 1 ohm anyway. The subs cannot be wired to 2 ohms each then bridged to 1 ohm at the amp. Doesn't make sense to me. Now you could wire each sub to 2 ohms and have a sub hooked up to two speaker inputs on the amp that is internally bridged, but the amp will still see a final load of 4 ohms. Someone help me out here!!!

Just out of curiousity what head unit do you have? What other components do you have installed? Another amp? Upgraded or stock speakers?

Come on man, I'm trying to help! Screw the shop!! Is the box ported or sealed? What vehicle? Where are the subs? How are the subs wired?

If you have 2 dual 4 assassins the only configuration you could wire them in is 1 or 4 ohm. That memphis amp is not 1 ohm stable so, maybe they are wired to 4 ohm load and a 4 ohm load on that amp is 250 watts, so 125 to each sub.

Well, maybe go and look at the box real quick to see if it is in fact ported or sealed. What vehicle are we talking about and were are the subs located in said vehicle. Are the subs wired correctly for that amp?

Is the box ported or sealed?