Measuring Amplifiers - Page 18

Very impressive! Can't wait to see the bridged @ 4 ohm results.

Hmm, thats odd, other tests I have seen have shown the PLX class H designs being high frequency monsters, I have seen the 2ohm results getting over 2500wpc at 20Khz, it looks more bottom heavy here.

Will the PLX3402 accept 220V input? I currently am using one EP2500 for my four IXL-18's in sealed cabinets. I would like to add more power and have run a dedicated 220V line to my component rack. I want to use an amp or amps that are capable of 220V input.

Not bad!

Comments.

I had my PLX3402 on the test bench for a month torturing it, and even blowing it up, lol.
I even did cap mods......

With no variac, I was only able to get 2kw rms in bridged mode @ 4 ohms with 110VAC
input, 20hz tone for about 10 seconds before the amp went into protect mode. I talked
to Bob Lee about this. He said it will do over 3400w in bridged mode @ 4 ohms
with 120VAC input, not 110VAC. But this was a long time ago. Later I looked
at the datasheet for PLX series and the higher power ratings are not for any frequency
other than 1khz!!!!!

http://www.qscaudio.com/products/amps/plx/plx.htm

20hz - 20khz rating;

It's rated for 1100w/ch @ 4 ohms/ch.

It's rated for 2200w bridged @ 8 ohms.

Only the 1khz test shows more output, 1700w/ch @ 2 ohms,
3400w bridged @ 4 ohms.

It doesn't matter to me. 2kw or 3kw, who cares. I have ten of these amplifiers and
there is no need to be nitpicky ... I just find it odd that an extra 10VAC could
skew the data so much, but if you look at Binks pro amp tests, 117VAC vs. 96VAC,
21 volts can make a big difference, so I guess 10VAC can make a difference. lol



I linked a test a while back from the prosound forum. I believe someone was
doing burst tests on a few amps. I thought the PLX3402 did 5kw [total] with
a 25mS or 50mS burst. I can see this happening because the PLX has high voltage
rails and a transient like that can record big numbers. But if you do continuous
sine waves, forget it. All amplifiers will record lower numbers than easy burst tests.

Questions
1. Your PLX tested at approx 2kw/ch in stereo mode @ 2 ohms/ch. I'm assuming
this is not a 'both channels driven test' as there is no way this amp will do 4kw
total. hehe .. If you read 2800w @ 1khz, bridged mode @ 4 ohms, but blew many fuses trying to do
these bridged mode tests, then you would be blowing fuses like mad on the stereo test trying to register 4kw rms.

2. What is the AC input voltage? Your tests never show this as it's an important
variable. Low AC input can cause amplifier scores to register low numbers, or
generous 'unrealistic' higher input voltages can make the amp look like
a Wall Street darling. lol

Thanks for the tests Chuck! I wasn't expecting new tests today but its always a treat. Great results I think. And looking at completed ebay listings, the average price for a used 3402 seems to be ~$690.

re: post 13


QSC says the PLX's are tested with both channels driven [stereo mode]
http://www.qscaudio.com/products/amps/plx/plx.htm

Your test was done with one channel driven. You didn't follow your own
testing protocols, naughty naughty

The amplifier testing debate rages on, everyone debates on what is
a proper methodology. The problem is, there is too many variables.

Is the rms test method the best? This is akin to a continous test tone.
Is music a continous test tone? Usually not, perhaps on a rare piece of
music you might find a continous test tone. Maybe a 'special effect' found
on movies. Overal, the rms method is my favorite method because it will
torture the amplifier more than those easier tests that inflate the scores.

What if you do an rms test method plus a burst test to mimick music playback in general?
This is good too, I like this a lot.

Test duration? This is so important, yet overlooked by everyone. How
long was test performed for? Was the scores captured after
a 1 second test? 10 seconds? 1 minute? 1 hour? Manufacturers might follow
certain guidelines, but what is a good time period ? Perhaps a better
test is just to note how long the amplifier performed using a certain
ambient temperature as a reference. In other words, you
hook up the amp at a reasonable ambient temp, run the amp to full power,
then write down how long it operated before going into thermal protect
and/or blowing a fuse, or blowing itself up. hehehe

Test Duration Example;

* I tested my PLX at 2kw total.

* You tested the same amp at 4kw total.

* Lets throw in the the Crest 10001, I got 4kw - 5.5kw bridged depending
on if it was a 2 ohm or 4 ohm load.

A person looking at this data will assume the PLX is the same as the Crest.

But the test method and duration tell a bigger story. My PLX test is
both channels driven. Your PLX test is one channel driven, the Crest
is two channels driven. My PLX went into protect mode after 10 seconds,
your PLX had issues very quickly, but the Crest ran all day without going
into thermal protect.

PLX3402 is my favorite 'general purpose' high end amplifier. Excellent for midranges and
tweeters, works great for subwoofers, but expect less power. But if you were to use
an LMS-5400 caliber woofer [or equivalent, or beefier] and needed only one amplifier,
the PLX, PLX2 isn't good enough.

Yeah, they come and go a lot, sometimes I can't find any for under $1000 for weeks, other times it seems the site is full of buy it now's for under $750, one time I saw a lot of 10 2402's go for $3100, I wish I would have bit but I didn't have the cash at the time, tuition is killing me.

PLX3402 pricing. Before PLX2 was released, I paid an average of $765 each.
About a year later, when PLX2 and new Crown amps came out, it seemed like the
upgrade itch hit certain people and they were selling their older PLX's for about
$100 less, for a certain time period. I saw some sell for ~$550 each. I would say
that $550 - $750 is a good price. When you look at the performance numbers
and compare this to high end home audio amplifiers with much less power that cost
thousands, these used PLX's are a bargain. PLX2402, 3002, 3402 are the class H
models, get those to have class H 'high rail'.

Or would that be wasted bandwidth?

Yeah, its like that with a lot of products.

It was the same with the CEs.

This thread is fantastic. I would love it if you tested a standard home reciever to see how it measures up in these tests. That testing equipment you have is very sexy, like Dr. Frankenstein's lab. LOL.

[quote=thylantyr;12942259]
It doesn't matter to me. 2kw or 3kw, who cares. I have ten of these amplifiers and
there is no need to be nitpicky
I believe someone was doing burst tests on a few amps. I thought the PLX3402 did 5kw [total] with
a 25mS or 50mS burst. I can see this happening because the PLX has high voltage
rails and a transient like that can record big numbers. But if you do continuous
sine waves, forget it. All amplifiers will record lower numbers than easy burst tests.

Thylantyr,
You're an interesting guy but I can't quite grasp where you're headed or what your ultimate system is going to look like.
You have 10 PLX3402s and you seem to have a complaint about them but add don't be nitpicky. LOL
In a following post you say the PLX3402 is not suitable for an LMS-5400. An LMS-5400 is rated for 2500 watts but under real in-box results that amount of power is not required to reach full output in the 10-80Hz region.
Using Ilkka's testing of the LMS-5400 driven by the CE4000 as an example, the LMS-5400 exceeds the 100 db level for most of the 10-80Hz range and seems to be the best sub performance so far. My question is how loud are you wanting to go and what are you willing to acquire to get there? What amp is suitable to drive the LMS-5400 or isn't there one?

I complain about everything I can look at any amplifier
and nitpick, but in reality I really like the PLX for mids
and tweeters. People in home audio love it for subs.
1/2 the people on the pro audio forum don't think it's
as powerful for bass. It depends on what you want.


Depends on the subwoofer design. An LMS in a certain
design may reach limits with 200w, in another design
it may need a few thousand. That's why people who
build subwoofers need to look at the power requirements
of the subwoofer [driver + enclosure design].


The CE4000 amp craze on AVS was started by me,
at first in PM's, then word leaked out and now everyone
knows about that amplifier, awesome for subs for it's
price range.

CE4000 > PLX series for subs. But for mids/tweeters, I prefer the PLX.

I see the Crown website announced it is offering "Anniversary Editions" of the former Macro-Tech Amplifiers in various watt ratings and are limited in production numbers. They have a "Copper" face plate.

Also they now offer a new model in the XLS series, the XLS 5000.
5000 watts bridge-mono @ 4 ohms.

I see you ran into some "doubters" about the QSC PL380. I've read those people on other threads, they sure like to do a lot of abstract "theoretical testing" . But then I haven't run into any engineers who weren't genetically driven any other way.

The Crown K1 is on clearance at a store near me for around $690. Is that a good Amp for the money to drive passive subwoofers? How does it compare to the QSC RMX2450?

Thats not a good deal for the K1.

E.bay has K1 for 'buy it now' $495.

I would expect similar performance to RMX2450.
You might as well just get an EP2500 for $265 - $350
as all three of these amps would be in a similar boat.

If you want to spend $690, look for used amps, CE4000, PLX3402, Crown Xs was
tested well here. This will take you to the next level.

thylantyr,

Great info,as always.