revvenue

Hey guys, been lurking around the forums since I purchased my Z back late last year (2003 Silverstone) but haven't had a chance to really make any useful posts yet since I've just been absorbing as much information as possible since .

Anyway I decided to do an audio install after receiving only outrageous install quotes from the mediocre shops in my area... and it's hard to let your baby be worked on by someone else anyway

I researched this online last night for at least 4-6 hours and still don't have a definitive answer about wiring this up so I figured there has to be a pro here who could help me solve this problem.

The problem I'm running in to is that I have a Rockford Fosgate T400-4 4 channel amplifier that I am wiring to a set of components in the front (4ohm) which I'd also like to use as a temporary amplifier (until I purchase a mono-- funds limited) with the 3/4 channels bridged to a 500w 10" JL 10w3v2 2ohm Single Voice Coil sub. I've been looking at wiring diagrams from Crutchfield, etc. but none have any options to run a 2ohm svc bridged... only from a mono. Everything I've read requires a DVC @ 4ohms bridges to 2ohms.

The manual for the amplifier says the amp is rated at xWatts for 2ohm and "stable" for 1ohm. If I bridge it for the subwoofer this would create a 1ohm load on the bridged channels and a 4ohm load for the front components from what I can tell (I think this is correct...) My birthsheet for the RF amp reads 700+ Watts @ 1ohm.

For your convenience here are the products I am talking about:

Amp: http://www.rockfordfosgate.com/produ...n_US&p_status=

Amp Manual: http://www.rockfordfosgate.com/scrip...%3Afaqs.faq_id (4 channel listed there)

Sub: http://www.amazon.com/JL-AUDIO-10W3V.../dp/B000TDCN2Q

My question boils down to a few things (TL/DR version):

• Can the JL sub run at 1ohm if I bridge it since it is a 2ohm SVC sub?
• If it is even possible to run @ 1 ohm will it kill my amp after a few months?
• And lastly... if it's not possible to bridge it, how would I go about running the sub from 1 channel if the signal from the channel is stereo and not mono?

And finally... I've read every thread in this forum concerning removal of door panels, etc. and it truly has been a Godsend to bring my laptop out to the car and work through problems. I've become a lot closer to me Z because of this forum! Thank you to everyone who has given their time and knowledge to this forum... it really is very much appreciated. Thanks again in advance for any helpful advice so I can finally put this job to rest!!!

Paul350Z

iTrader: (1)

"to run a 2ohm svc bridged... only from a mono. Everything I've read requires a DVC @ 4ohms bridges to 2ohms."

Simple math. You have a JL Audio 10W3 with a 2 Ohm dual voice coil. You can wire this subwoofer to be a 4 ohm or a 1 Ohm speaker - or run it as a pair of stereo 2 ohm coils. I can find nothing in the amplifier's manual stating that it's 1 ohm stable - 2 ohms is what I find. So I would recommend wiring your two coils in series with one coils (-) to the next one's (+) and then using the first coil's (+) and the second's (-) as the inputs.

The advantage of running your amplifier at or near its lowest acceptable impedance (ohms) is that you're going to increase the amount of current and therefore watts driving it. There is a downside in that lower resistance subwoofers suffer from poor dampening - that is the amplifier has a "difficulty" controlling them (in very lay terms). A somewhat higher resistance coil has higher dampening and therefore tighter more transient bass. This is the kind of base response I enjoy, and I think I've heard the people here referrer to this in lay terms as "hits hard" vice "sounds loud".

I've seen more 40 watt amplifiers burn out 100 watt speakers than 100 watt amps burn out 40 watt speakers. Likely because people who buy cheap amplifiers also lack the ability to hear 10%-20% clipping which absolutely kills speakers. Rather than dissipating the energy (watts) as kinetic motion (sound) the coil pauses at the top and bottom of each square wave (clipping) and dissipates the energy as heat. Eventually the heat builds up and burns up a coil winding or melts the glue holding the coil to the cone or basket.

An amp driving too small of a load will normally go into thermal protect or overload protect pretty quickly. I have an amp that will not even attempt to drive too small of a load choosing to protect itself rather than to entertain me. Fair enough.

In the amplifier manual on page 8 the middle diagram is how to wire your amplifier to your speakers. The front channels feed your front speakers and the rear two channels feed the subwoofer by using the (+) connection from the left and the (-) connection from the right. The text on the bottom of this page has you feed the inputs to the front channel only, have the 2/4 channel switch sent to 2 channel, use the gain front and rear to suit your needs, and the crossover front and rear set to match the speakers. I would set the front EQ to HP (high pass) and the rear to LP (low pass) with the crossover at 70 Hz and then play with them +/- about 10 Hz.

The amp should give you 60 watts to your front 4 ohm speakers and 120 watts to your rear 4 ohm (2+2) subwoofer. This isn't going to be too bad at all but I would recommend some more horse power on that subwoofer. Depending on how sensitive your front speakers are and how loud you listen this might be plenty loud enough. Understand that 3dB is a barely noticeable increase in sound and you'll have to double the size of the amplifier to do that. Going from 60 watts to 100-120 watts up front will just barely be noticeable. Back aft with the woofer you can go from 120 watts to 400-500 watts and get another 6-8 dB which is a bit more.

revvenue

Hey Paul,

Firstly thank you so much for taking the time to offer such a detailed and helpful reply.

Unfortunately the subwoofer I have is not a DVC subwoofer, which is where the issue is... It's a SVC @ 2ohm. If I run it to channel 3/4 bridged as the manual shows it should run a 1ohm load, right?

That is where my main confusion is coming from. The subwoofer is saying it's a SVC on the back as well as on the Amazon website. When I check out the JL website and get the manual they all show the 10w3v2's as DVC @ 4ohm, which would be very easy to bridge on this amp @ a 2ohm load. They don't have any information about the 10" 2ohm, which I find strange. The DVC is rated @ 300w RMS while my sub is rated @ 500w RMS, I suppose due to the difference in ohms, etc.

Anyway, my question is bridging a 2ohm SVC sub to this amp.

Thanks again to anyone who can help me out... My mind is boggled here... !!

THEDUKE

iTrader: (24)

How many terminals does it have? One set or two sets? If it only has one set use a meter to see what the Ohms are. It will not be exact, but close enough to tell you what it is. For example if it is a 4 Ohm it might show 3.8 or 4.2 on the meter. If it turns out you have a SVC 2 Ohm woofer you might end up having to get a new woofer or a new amp. Your amp cannot handle a 2 Ohm load bridged on the rear channels. It might work a a little, but get very hot and shut down or even go bad.

revvenue

Thanks Duke, that's what I was afraid of. It does have 2 terminals which I would think confirm it is definitely SVC as the magnet reads. I will check the ohms just to be positive, but if it is definitely a 2ohm SVC, is it possible to run it on 1 channel @ 2ohms temporarily until I get a mono amp next month, or should I even bother?

Thanks again guys.

revvenue

Oh, and just to let you know I'm not completely ignorant, I just got most of this equipment new from different trades and didn't really pay much attention to the ohmage on that sub... Still a mistake, ah well! I plan on adding another amp in a month or so to give that sub 500 watts or so... Just looking for a little bass temporarily.

Z1NONLY

iTrader: (2)

You could just run the amp in 4 channel mode and not use one of the channels.

Most 4 channel amps can handle 2 ohm loads when run in 4ch mode. (just double check the owners manual for your amp)

If I were in your shoes, I would simply connect the 2ohm sub to one of the channels and accept the fact that I will be down on power. (and have one of the 4 channels connected to nothing. (the other two would be for the mids+highs)

revvenue

I think this will be the best option for my particular temporary application, since my sub box is already in there and I don't need the other 2 channels...

Just to quench my curiosity... If I did bridge this to both rear channels, would it run a 1ohm load and if so would a 2ohm svc sub work on 1ohm? I will not be bridging this but if anyone knows I'd like to know just for future reference.

Thank you everyone, for your input. Seriously, thanks!!!

Z1NONLY

iTrader: (2)

Unless your amp is stable into 2 ohms bridged / 1 ohm "stereo", (un-bridged) connecting your 2 ohm sub to a bridged pair of channels will cause the amp to go into "protect" mode and/or become a "blue-smoke generator".

(It could kill your amp.)

Paul350Z

iTrader: (1)

2 ohm single voice coil - you're golden.

The amp will be stable bridged across a 2 ohm load and provide 200 watts maximum.

Speakers change impedances when coupled together, not amplifiers.

Z1NONLY

iTrader: (2)

http://www.sonicelectronix.com/item_...+Red+Box-.html

^^This link says your amp can handle 2 ohms bridged.^^

If this is accurate, your 2 ohm sub can indeed be connected to a bridged set of channels on that amp.

revvenue

Hey guys, thanks a lot for the help. This is what I had originally thought, but after looking over several wiring diagrams, etc. it somehow was ingrained in my mind that I needed a 4ohm dvc to bridge over 2 channels.

Once I read your replies, I'm just thinking "DUH!!!"

I think I need some rest from staying up this week with this install :P

Thanks again!!!

THEDUKE

iTrader: (24)

When ever you bridge an amp it sees half of what you are giving it. In this case the amp will actually be seeing a 1 Ohm load since you are giving it a 2Ohm load. This will not work.

revvenue

Now I'm confused... because I had also thought this was true for a while...

When I talk to audio guys they either tell me I can bridge channels 3+4 and get 2ohms for the sub and be ok, and other guys tell me if I bridge a 2ohm SVC from this amp it will be 1ohm, even though the subwoofer is a 2ohm?

I just didn't think it was possible to get a 1ohm draw even if the subwoofer is bridged, if it's a 2ohm subwoofer.

Z1NONLY

iTrader: (2)

The link I provided above says your amp can handle a 1 ohm load. ( same as connecting a 2 ohm load when 2 channels are bridged)

revvenue

Just as I thought originally. So the bridge will create a 1ohm load but my amp is okay per the manual it can handle a 1ohm load. Thanks for the clarification guys, it's truly a lifesaver here...

Litesung

You could always take the easy way and just try it and see if it works out... haha but I wouldn't do that.

GL

Litesung

Let's do some physics together! V=IR right?

hope that helps >.< (seriously)

revvenue

Yes, that helped immensely thanks for taking the time to stop by .

revvenue

Just an update to anyone who was curious...

So I decided to bridge the 2 ohm SVC sub on channels 3/4 of my 4 chan amp, had gain turned to minimum (was about to tune it) turned the volume up about 70-75% + my sub @ 50hz before clipping the speaker wire in.

After plugging my speaker wire up I cranked the car back up (after setting the volume @ 70% / 50hz for the sub output) I got some bass. I turned the gain up about 1/3 and sat back down to listen for a while... turned the volume to about 75% and I'm not sure if it clipped or what but my sub ripped to shreds.

Someone told me it was because the box is not ported (under strut box)
Someone told me it was because I bridged the 2ohm svc sub.

My amp had no problems powering it... I guess the sub just gave in.

My question is that since I will now be buying a replacement I have control over the sub I purchase. Any recommendations for ohms on this? Should I buy a 4ohm DVC sub to get my max (safe) wattage output, since this is being bridged? Or did I do something incorrectly with the setup? Pics just for the fun of it...