Soundstream XTA720.4 VS. JL 300/4

3onDubs · 02-01-2006, 09:26 PM

Which amp would better suit my speakers? I will be running the amp in 2 channel bridged mode because I have no rears. I am running 2 CDT EF-61 components. Here are the details for the components and amps...

CDT EF-61
6.5" 2-way
Midrange: 6.5" Cast Carbon Treated Paper Cone
Crossover: SatNet-400 Elliptic 4th/5th order 2-way
Tweeter: TW-24 1" Smooth Silk Dome
Power handling: 120 watt RMS
Frequency response: 60-20kHz
Sensitivity: 90.5 dB.
Impedance: 4 Ohm
Surface & swivel flush mount housings

Soundstream XTA720.4
90 X 4 at 4 ohms Output RMS
180 X 4 at 2 ohms RMS
360 X 2 at 4 ohms RMS
0.05% THD
10 - 30k Hz Frequency Response
96db Signal To Noise Ratio
200 Damping Factor
200mv Input Sensitvity
12db Crosover Slopes
30 - 500 HZ Crossover Frequency High-Pass
30-150 Hz Low-Pass
0 - 18db Subwoofer EQ
Bi-Linear Selectable Crossovers For Inputs And Outputs
Continuously Variable High And Low-Pass Crossovers
Variable Subwoofer Equalizer
Phase Inversion Switch (0 - 180º)
Platinum 4-Gauge Power Connectors
Tri-Mode Operation

JL Audio 300/4
Rated Power (4 Channel Mode): 75 W RMS x 4 @ 1.5 ohm-4 ohm (11V-14.5V)
Rated Power (Bridged to 2 Channel): 150 W RMS x 2 @ 3 ohm-8 ohm (11V-14.5V)
THD at Rated Power: <0.03% @ 4 ohm per ch.
S/N Ratio: >108.5 dB below rated power (A-weighted, 20 Hz - 20 kHz noise bandwidth)
Frequency Response: 5 Hz - 30 kHz (+0, -1dB)
Damping Factor: >200 @ 4 ohm per ch. / 50 Hz >100 @ 2 ohm per ch. / 50 Hz
Slew Rate: ±25 V / µS @ 4 ohm per ch.
Left to Right Channel Separation: >75 dB @ 1 kHz
Input Range: Switchable from 200mV-2V RMS to 800mV-8V RMS

keen70 · 02-01-2006, 09:59 PM

IMO id use the JL

3onDubs · 02-02-2006, 01:29 PM

I feel like an idiot...i just re-read the stats on the soundstream and I see that it puts out 360 X 2 @ 4 ohms. I have been bridging my channels and running my fronts off of this thinking that I was giving each speaker 180 watts. I reverted back to using it in 4 channel mode so that I can send 90 watts to each speaker.

Does this sound right (the fact that it jumps from 90 to 360 when bridged)?

How would I be able to get 180 watts to each speaker? The only way I can think of is to run both speakers off of one shared bridged channel. The only draw back to this would be that I would lose balance control (which I never use anyway). Is there an easier way?

Chillboy · 02-02-2006, 02:12 PM

Sure it will run 360W but the amp is really seeing a 2ohm load so distortion is above .5% and prob just under an audible 1%.

If you are using a 4ch amp and only want to run front speakers off it you should invest in an electronic xover and run 3-way active imo.
You can get one really cheap off Ebay now since amps have built in xovers. I don't think that yours has the range or bandpass capability you need to do this so you would need an external one.
IMO it will sound much better then running bridged into each side.

EDIT you can always turn the gains down to where you need them.

3onDubs · 02-02-2006, 02:24 PM

Quote: Originally Posted by Chillboy

Sure it will run 360W but the amp is really seeing a 2ohm load so distortion is above .5% and prob just under an audible 1%.

If you are using a 4ch amp and only want to run front speakers off it you should invest in an electronic xover and run 3-way active imo.
You can get one really cheap off Ebay now since amps have built in xovers. I don't think that yours has the range or bandpass capability you need to do this so you would need an external one.
IMO it will sound much better then running bridged into each side.

EDIT you can always turn the gains down to where you need them.

I am using a Digital Sound Processor that feeds my amps. It has a built in electronic crossover so it would allow me to run an active setup. I was doing this originally, but I couldn't get the tuning down, so I just went back to using my passive crossovers for now.

What do you mean by 3 way active? My components are only 2 way....Do you mean tweeters, midranges, and subs?

I have read through many active vs. passive debates, and there have been arguments for both sides....is active potentially better than passive if tuned properly?

Chillboy · 02-02-2006, 03:45 PM

Quote: Originally Posted by 3onDubs

I am using a Digital Sound Processor that feeds my amps. It has a built in electronic crossover so it would allow me to run an active setup. I was doing this originally, but I couldn't get the tuning down, so I just went back to using my passive crossovers for now.

What do you mean by 3 way active? My components are only 2 way....Do you mean tweeters, midranges, and subs?

I have read through many active vs. passive debates, and there have been arguments for both sides....is active potentially better than passive if tuned properly?

It is debatable. I've had a couple 3way active systems but run an amp that like passives better now (tube amp). But I think in your case with wanting to max the power without over powering (or 2ohm loading only to turn the gains back down) combined the control you already have in your system that you should give it another try. It gives much more control over the system and you should set xover points eq flat first then tune to your liking.
Yeah 3-way active = tweeters, mid(bass), sub. I guess you have another amp on the rears and one on the subs too.

The easiest way to explain the benefits is do you want to amplify a full range signal and cut a bunch of sound out or do you want to amplify the specific range you want to the speaker. Also tweeters are very sensitive. You'll end up setting the gain way lower on those channels and get the same output to match your mids. A friend with an o-scope and rta would make things really easy but start with a flat eq or even better your noise generator to match the output to each type of speaker.

3onDubs · 02-02-2006, 04:42 PM

I'm actually running two amps and no rear speakers. One for the fronts and one for the subs. I always figured that it would be a waste of power to only amplify a part of the signal...why not amplify the full signal (and let the passives do the work) and free up a couple channels on the amp? This would be helpful to those with a shortage of channels.

I know that this deserves a different thread, but what are the benefits of a passive crossover over an active setup. I know that the passives are designed specifically for the speaker...what exactly do they do other than cut off frequencies at a specific slope?

Chillboy · 02-02-2006, 06:44 PM

Basically electronic xovers can be tailored to your car (listening environment) better. There's something to be said for a companies matched passives but unless they are really high end and you see lots of caps and coils to get a steep slopping x-over point then the electronic will prob own it.

If you amplify the range of 0-80Hz to your sub, doesn't that make more sense that you will get more output then if you aplified 0-22kHz and chopped out part of the signal? That's a pro for electronic xover but I don't want to weigh too heavy on that unless you compete in spl.

I think I mentioned that the only reason I use passives in my car now is that it's tube amped. They like a passive (generally) and they aren't efficient amps to begin with so why bother (my stereo gets louder then I like it), great reason is $ for another tube too but you already have 4ch's to play with. But if you can put more power to the midbass then the tweeter you will get more precence (fuller sound) at lower volumes.

You have all the equip to run a nice 3 way setup. I'd give it another try but flatten your eq and run the white noise to get balanced output before you play with the settings. Set your headunit about 5 notches under the max vol 1st too since you can't oscope it to see where it clips.

I'll guess the passives are 12dB/oct and your headunit/processor has nice 24dB/oct xovers built in (check I'm guessing). That means that if your manual for the components says xover point is 5K hz then you could prob let them play down to 4K hz (just an ex.). Don't forget that each speaker may sound like crap on it's own, just listen for distortion to set the midbass then match the tweeter with white noise generator or music you know.

If it's still too much to think about there's nothing wrong with putting it in and having a local shop rta tune it for an hour to get you going. Stereo is the easy part for me it's deciding on setup for carputer that makes me scratch my head.

Give it a try. I think maybe you had the xover set wrong or something first time around. It should sound better. You should be able to tune it exactly the way you want it.

Chillboy · 02-02-2006, 06:50 PM

Last tip that I can offer is that if you have a decent home stereo, use it to help train your ear before you start to tune. After a little while you forget what you are supposed to hear sometimes.
And I am no expert just a hobbyist, that's kinda rusty with todays equip., but the tuning almost remains the same.

3onDubs · 02-02-2006, 07:11 PM

You're right...active setups can definitely be tailored to your car better. I know that if I was more patient with tuning my setup or if I had an expert to help out, then I would have definitely been able to get my speakers to sound right.

The sound processor that I am using is actually loaded with features. I think that the slope on the x-over goes down to 36db for a really sharp cut off. You've convinced me to give active a second chance....I think I'll run my amp amp in 4 channel mode and give two channels to the tweeters and ditch my passives. I'll probably set it up and take it to an audio shop to see what they can do with the tuning.

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?

Thanks for all your input Chillboy....just out of curiousity, what kind of a set up are you running in your car? Head-unit or no headunit?

Chillboy · 02-02-2006, 09:47 PM

Quote: 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!!!

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