# Soundstream Stealth amps, my initial review.



## Barnaby (Aug 25, 2009)

*Soundstream Stealth STL4.320 and STL2.350 amps: * The STL4.320 is rated for 50x4 or 160x2 and STL2.350 is rated for 100x2 or 350x1 all into 4ohms. Soundstream Brochure. Sorry no pictures of my own.

*Purchase:* I picked up one of each of these amps ~ a month or so ago and have now had a chance to play with just about every part of them (from a UI standpoint).

The amps came appropriately packaged and wrapped, both were in perfect shape and NIB from the eBay seller Autosounds4less. Very quick shipping as well as a pretty cheap price on these. I think I paid ~$310 shipped for both amps.

*Appearance: * All of the connections are fairly heavy duty and certainly held the wire I am using with them (8ga power). There are no fuses at the amp though. 

They are stack-able amps and have these hideous chrome side bars that they use to both cover the gap between two stacked amps as well as extras to use as "beauty" trim. They are ugly and not necessary at all IMO. I will be relocating them in a stacked configuration and I will devise a way to NOT use them for stacking. They are actually pretty attractive amps without the side bars.

They are also fairly compact at around 6"x9" without wires attached. Power/speaker connections are one end and input and controls at the other.

*System: * They're wired into my bastard system which consists of a factory VW HU wired to a Audio Control Lc6i into these two amps. Speakers are PPI 356CS in the front doors, stock speakers in the rear panels (more on that later) and a Memphis 10" shallow mount sub in a Uber Stealth (Nik Brewer) enclosure. It's a 2008 VW GTI for reference. 

*Noise: * With the gains turned all the way down and using the output controls from the Lc6i I can not detect any noise at all. I have also had the opportunity to turn up the gains on both amps in testing and still could not detect any noise (silence between tracks was my test).

*Output/controls: * The STL2.350 is bridged for the sub and has no problems over powering the Memphis sub in that enclosure. It is a 4ohm sub, so the amp is supposed to be putting out 350 into 1 channel in that config. It has both a LPF as well as a HPF (can be used as subsonic to some degree), they are both 12db/oct. They work as advertised. It is mounted in the worst possible environment, in a factory Styrofoam cubby hole that's been cut out to fit extremely tight (one side has no clearance between the heat sinks and the Styrofoam) and then it's covered with a factory carpeted floor panel. The good news is that even mounted like this and bridged it does not get remotely warm to the touch. I have spent hours playing the system at reasonable volumes (can't talk over the music) and it's been great like this.

The STL4.320 was originally configured in 4 channel mode powering all of the factory speakers. To be honest, this amp ROCKED in that application. I was almost ready to leave well enough alone and stop with the system that way. With the crossovers doing their job and the sub doing it's job it made for a really nice sounding daily driver. The dynamics of the factory speakers were incredibly improved and the midbass was now actually felt as well as heard. This amp is mounted under the drivers seat and like the 2.350 does not get even remotely warm.

Then I got the wild hair to make changes to change out the front speakers to the PPIs and have pods built for the mids and tweets. Here's the amp started to struggle. It was still in 4 channel mode when I had the pods built. I couldn't get the sound I was looking for at all, it was thin almost hollow (think singing through a paper towel tube). I addressed the pods and the installation and got the sound a bit better, but I suspected that the amp was under powering the PPIs. I then bridged the amp, which is rated for 160WPC in 2 channel mode. This was a huge improvement in both dynamics (duh) as well as reducing the paper towel effect. I also disconnected the rear fill completely in this setup..

When bridging I did find some issues that don't exist when in 4 channel mode. They all center around the crossover and gain controls. For the gains, I needed to balance the left and right signals but they are not continuous controls. They are detented (this may be the norm anymore IDK, if so then this is just a gripe), thus making finding that perfect adjustment just out of reach. It's acceptable though. Then comes the crossover settings; in 4 channel mode there is an indipendent setting for the front and the rear channels. The front has a range from 50-4Khz and the rear has a range of 15-500hz, sounds good enough until you bridge the amp. Now you have independent crossovers for each channel, with different ranges, and only a low and high mark on the panel. So trying to set the crossovers the same for each of the bridged channels is a guessing game and since they are detented there's only so many guesses you can make. 

*Overall: * I like the amps when used in standard configurations. Some of the bells and whistles fall a bit short when bridging, although the power is very acceptable in the right application. I am planning on changing the system one more time and adding another Stealth amp (400watt mono version) and either biamping or running active for the fronts.


----------



## billg1230 (Jul 17, 2009)

The PPI's a rather inefficient speakers. They need at least 100 watts to get them going, So I'm not too surprised that the 50w in 4 channel mode wasnt cutting it.

That "paper towel roll" sound is probably an effect of your enclusures being too small.
Download winISD speaker modeling program and put the specs for the driver in. You will see a big ol' peak in the response at 200-300 HZ if the enclosure is too small.


----------



## Barnaby (Aug 25, 2009)

The pods are vented through the door panel (3" hole) so it's probably more due to speaker location or something else on the car. I appreciate the advice, I'll model the speakers and see what it spits out.


----------



## AAAAAAA (Oct 5, 2007)

Nice, I am happy that they don't get warm. Nothing can beat these guys power\size\feature\price ratio.

Just in case it was missed, the rears can be used as band pass.


----------

