why are the lower jl audio amps so cheap?

Most of them do not, in fact most new ones are class D on subs and a whole separate amp. Reason most can't is because the sub has to run higher voltage for more RMS, and you can make a huge dual out transformer but most don't want a huge thing like that in there if they don't have to....and yes it could screw with the highs....so I've never seen one that had one trans in a 5ch. Try to get a look at the guts, check out some 5ch on ampguts and you can see.

Don't know what model this is, but is typical:
http://ampguts.realmofexcursion.com/JL_500_5/inside1.jpg
Here you can see two transformers in the upper right. See the white ceramic emitter resistors in the upper left in a row, two for each of the four class AB channels. The green wire wound inductors in the center are likely on the outputs for the class D sub channel. On the lower right you can see a bank of caps for a PS, then to the left of the transformers another bank of smaller caps for the other PS. Could be the class D PS is actually smaller than the 4ch, would likely take less power at 250w/80%+ efficiency than 250w/60% efficiency for the 4ch part.

Reasonably good brand should work fine far as PS, with 5ch the bad part is you can't upgrade anything. Newer amps the PS is a little different and they can make the same power and be smaller than old amps. It really depends on the amp itself, you can make one or two PS work in a 2ch amp....I have an insignia 2ch with two but that does not make it a fantastic amp. Have an ultra linear the same way each ch is its own amp except for the inputs. A lot of great old school amps have one transformer.

gentlejax2 said:

reliable? I worry about any amp that runs mids/tweets on other channels while trying to push a sub off one power supply...its a lot of stress...
thats why I wonder if there is some difference in the JL...

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AristoPra said:

darn it and i just bought a used one too! ! ! i was going to power a pair of ed 6500 and ed 6000v2's and a pair of ed7kv.2 subs. . . any suggestions for a nooB? ? ? :blush:

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Guys, multi-channel amps powering a full system is not a new thing, this has been done for years. The sole reason a company like JL Audio would offer a 6 channel amp in their lower line product is to offer an all-in-one solution to the consumer on a budget. The 6450 amps were designed as a single amp solution to power the most common system config, FRONT, REAR and SUB configs. The amp is rated as such:

6 x 45W @ 4 ohms (12.5V - <0.08% THD)
6 x 70W @ 4 ohms (14.5V - <1% THD)
6 x 75W @ 2 ohms (12.5V)
6 x 110W @ 2 ohms (14.5V)
3 x 150W @ 4 ohms bridged (12.5V)
3 x 220W @ 4 ohms bridged (14.5V)
Fuse: External 60A

So,
At 12.5 volts, the amp will produce 450 watts of total power
At, 14.4 volts the amp will produce 660 watts of total power

That is not a ton of power but it is enough to stress out a too small power supply running 6 channels. The solution is to use a power supply that can deliver, and that is what JL did and what many modern car audio amplifier designers do. The power supply is unregulated so you get more power with a higher input voltage. I remember this amp was tested by a mag and it did the rated power in all channels at 12.5 volts. So, feel free to run the amp with a sub on channels 5&6 that is what it was designed for and I am sure the amp will deliver the goods.I don't know anything about the reliability of the A and e series amps but not every amp is going to fail...and chances are if these amps were used they would have failed by now. At under $200 one really can't go wrong with these...however, running two amps is always what we try to do but space savings does not always allow us to do that.

As far as the Slash amps, I did a couple of systems for a friend and he had the 500/5 powering a Front,Rear, Sub system. The amp was actually in a storage compartment in a Ford Explorer for a couple of years and it never shut down or had any noise issues. He still has the amp and plan to put it in a third system running full.

I remember my old 5 channel MTX Thunder5400x (ten years ago) was good for over 800 watts at full tilt. That amp was only 15"x9"x2" and used to get as hot as a griddle but it used to thump a full system.

Some people have very misguided ideas about amplifiers... a single power supply on a multi-channel amp is neither uncommon (if the channels are symmetrical), or unreliable. Quite the contrary, the power supply is LESS likely to be stressed than on a mono amplifier.

Here are the guts of an e6450, which is essentially very similar to the A6450 or the G6600:



The E/A/G-series JL Audio amplifiers are very reliable and built to a higher standard than most other amps in their price class. They have the same amp circuits as the more expensive Slash amps, but with a simpler (unregulated) power supply. They all feature differential-balanced inputs, the A and G-series feature rollback protection and a few other benefits very rarely found even at double the price.