Soundstream XTA720.4 VS. JL 300/4

**Chillboy** · 02-02-2006, 09:47 PM

Originally Posted by 3onDubs

The reason I was asking about the JL amp is because I just purchased the amp from another mp3 member and I was wondering how it compares to my current amp. I still havn't received it, but I would probably be running it in bridged 2 channel mode so that my speakers would get 150 watts each.

I had a quick question about ohm calculations. The JL amp says that it outputs 150 watts in bridged mode for 3-8 ohms. If I were to run both midranges to the same bridged channel and then run both tweeters to the other bridged channel, would both channels see an 8 ohm load? If so, would all four drivers be getting 150 watts a piece?

Get yours setup and running great and then swap it out for the JL at the same settings. Don't think that the most power wins but I think they are pretty equal quality if anything I'd give JL the edge. I'm a little outta the loop but both are good. Soundstream was the ish back in the day.
Forget about that second paragraph. The only thing you might want to do is bridge one into the midbasses in stereo and use only 2 chs off the other for tweeters. You could add rears later..I don't like them for music though.

I just bought a minipc and touch screen with the plan of not using the laptop for engine management.
Stereo now is a Nakamichi 40Z cd, Butler tubedriver750, Carver xover/processor (old skool but Holography adds a couple feet of width to the stage

), Harrison Labs 800D running 4ohm for 240W into a Dynaudio MW190 with an HLabs cap and Optima redtop in the trunk.
I picked up a Clarion dvd with dts and I'm going to stuff an Orion 6" coax in the dash, 51/4 punch fanatics in the rear and a Punch 4x25. I expect to have the extra speakers off 95% of the time.
I want to add the gps off a pda/phone. Then I'll be hooked up

**3onDubs** · 02-16-2006, 05:50 PM

I had 3 quick questions about ohmage......i know i might get flamed, but I'll ask them anyway while i move away from the monitor:

1. If I have two speakers that are 4 ohms each and I wire both speakers into the same channel on my amp....does the amp see a 2 ohm or 8 ohm load?

2. If I have 2 subwoofers that have dual 4 ohm coils, how should I wire them to get the maximum output on my amp? I'm assuming that a 1 ohm load would yield the most wattage.

3. Let's say that I managed to wire both of my subs down to one ohm (so that the amp sees one ohm) and let's say that the amp is a mono channel and can put out 1000 watts @ 1 ohm. Does each sub get 500 watts, or do they both get 1000 watts each?

**scott_fx** · 02-16-2006, 06:12 PM

check this out:
http://www.bcae1.com/spkrmlti.htm
http://www.edesignaudio.com/wiring.php
1:you'll have a 2 ohm if you wire both + terminals to the amp and likewise with the -
2: check this site: http://www.edesignaudio.com/wiring.php or each voice coil in par. and those leads in par. too.
3:they share the power, 500w a piece

also if you're getting new amps, check out the ed amps. they are pretty good amps and not that expensive.
this one: http://edesignaudio.com/product.php?cid=4&pid=6&cur=USD is stable to one ohm (1200 watts) and is only $350

**3onDubs** · 02-16-2006, 07:15 PM

Thanks scott......that was a really helpful link...answered all my questions. The reason I was asking is because I'm about to switch out my soundstream amp for the JL 300/4, and then I started thinking about ohmage.

I have two front speakers and two front tweeters. The speakers and tweeters need to be amped on seperate channels because I'm running an active crossover. The JL gives 75 watts on all four channels, but I need more power than that, so I will be running it in bridged two-channel mode.

Each channel on the JL will put out 150 watts @ 3-8 ohms. I was going to wire both of my front speakers to the same channel and then wire both of the tweeters to the other channel. I now see that if I did that, I would be placing a 2 ohm impedence on each channel, which the amp can't handle.

Are my calculations correct? The only other way that I can think of to get the 150 watts to each speaker would be to throw my crossovers back in or throw in another amp.

**scott_fx** · 02-16-2006, 07:28 PM

check the impedance on the speakers first, i think they are 4 ohms. i think the x-over has something to keep it at 4 ohms. i'm not 100% but check it with a multimeter (or ask cdt)

I'd also look into getting a phoenix gold ti500.4 (i think htats the model no) it is stable to 2 ohms bridged and is 75x4 @ 4 ohms. if you want to test it out before you purchase one feel free to stop on by, i have a spare one sitting in my room if you want to hook it up to hear it. This was my favorite amp before i got the xtant so don't worry about the quality, its a great amp and a beast.

oh yeah...
150watts is insane!!!

**3onDubs** · 02-17-2006, 11:50 AM

Ok, well I swapped out my amps yesterday with the exact same configuration. I changed nothing at all, simply moved the power, ground, and remote over to the JL and then moved all four speaker wires from the soundstream to the JL. I just wanted to compare how the two amps sound when running in 4 channel mode. The soundstream was running 90 X 4 and the JL is now running at 75 X 4.......the JL towers over the soundstream. I thought that I wouldn't notice any improvement (I actually expected a degradation of sound), but I adjusted the gains on the JL and my speakers are much clearer and louder. I don't even think I need to run the amp in bridged mode (although I am curious to see how that would sound).

Problem...After replacing the Soundstream with the JL, I now get alternator whine through my speakers...

...I thought that I had said goodbye to my engine whine when I went the optical route, but it's back! Does anybody know of a possible reason why the Soundstream wouldn't cause any engine noise, but the JL would?

Could it be because the JL's real time wattage is actually greater than the Soundstream's? There is a switch on the JL that says Lo Level Inputs / High Level Inputs....I put it on low level so that the amp could boost the signal a bit (and so that I could turn the gains down substantially...they're not even at half way). Could that be the cause?