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QSC PLX Recommended by Klippel

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Pjetrof

Pjetrof

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Really noone has objective experience with this amplifier?
Klippel is know to the enigeers here?
How far is there (klippel) recommendation list, recommended?
 

pjug

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tomtoo

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Klippel is known, they recommend a pro amp for there system. Thats why @Amir uses a pro amp. That says just this amp performs as good as what is needed for the system.

Edit says:
You know pro?
Reliabel,symmetric inputs, linear FR, good sinad, enough power. No schnickschnack.
 
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pjug

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Klippel is known, they recommend a pro amp for there system. Thats why @Amir uses a pro amp. That says just this amp performs as good as what is needed for the system.

Edit says:
You know pro?
Reliabel,symmetric inputs, linear FR, good sinad, enough power. No schnickschnack.
To each his own. Personally I don't want a fan in my amplifier.
 

tomtoo

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To each his own. Personally I don't want a fan in my amplifier.

Shure they recommend a amp for there system and usualy thats not in your living room. They not recomend a amp for the most pleasure in your home, they recomend a amp for a profesional measurement system.

Edit says: Dont get me wrong, i dont like fans. But thats for the usage maybe just not importend.
 
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Pjetrof

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Thx for the replies so far. Just from the Harbeth site where the designer closed the discussion about amps.
If those amplifiers are good enough for dr. Klippel ...
Just wondering someone used them at home and could tell something about the fan noise?
thx
 

DonH56

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There are a bunch of threads on AVS about using pro amps including QSC. By and large people who push them put them into a closet away from the listener area or modify the fans to reduce their noise.

Pro amps in general tend to provide high power per dollar (cost), and readily handle complex and low loads, but also tend to have higher noise and distortion than consumer amps.
 
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Pjetrof

Pjetrof

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There are a bunch of threads on AVS about using pro amps including QSC. By and large people who push them put them into a closet away from the listener area or modify the fans to reduce their noise.

Pro amps in general tend to provide high power per dollar (cost), and readily handle complex and low loads, but also tend to have higher noise and distortion than consumer amps.

thx Don, are those noise and distortion audible and are those important measurements to use klippel components to measure speakers.
I m not an EE technical i m not good can t change a lightbulb

My question is cause a speaker designer referred to the Klippel recommendations list.
To use a speaker on that list, even so that the amplifier question is closed.
But is there not a diffrence between an amplifier using for home use and listen to music vs an amplifier used to amplify signals for listening to measure speakers?
 

DonH56

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I cannot speak for Klippel. Your question seems simple but the answer can get very complicated because there are so many factors and variables beneath it.

Measurements often require multiple sweeps to obtain a reasonable average result and that will reduce noise. AFAIK, Klippel is focused on measuring loudspeakers, so they are probably pretty insensitive to noise but want enough power (and low enough output impedance, which tends to go with higher-power amplifiers) to drive "any" speaker without having to worry about how much the amplifier is contributing to the measurements. I'd also want an amplifier in a test system to be very robust to test errors like accidentally shorting the output when moving a speaker or pulling a wire off (open the output) when testing. Since speaker distortion is typically orders of magnitude (factors of ten) larger than amplifier distortion, having super-low amplifier distortion is probably not a big deal. That is also true in the home, of course, but chances are you are listening at lower levels than when testing a speaker. You want the test tones to be high enough to be well above any background noise; ideally you'd test in an anechoic (very quiet) chamber, but the Kipple system is designed to not require an anechoic chamber, and that means more noise in the room. Which means more power from the amplifier to rise above the noise.

Back to your question, there does not have to be a difference, and there is often a lot of overlap since a good amp is a good amp. Good performance matters for both applications, but which parts of the performance matter to you may be different than what matters in a test system. But you may weigh things (parameters) differently for a home system. If the amplifier is in the same room you might not want fans. You are probably driving a single set of speakers and can select the amp for those speakers instead of an amp to drive all speakers. If you have highly sensitive speakers like horns you may want less power and higher SNR (lower noise floor). If your speakers are not very sensitive, you sit fairly far away, and the speakers have low impedance and high phase angles (they are hard to drive), then you may want a higher-powered amplifier that can handle low-impedance loads. There are also aesthetics (looks); a home amplifier is often exposed in a console or on a shelf and you want it to look nice, or at least fit in with the rest of the components, while a test system amplifier is often in a rack with other test equipment and looks do not matter. You probably want basic circuit and speaker protection in a home amp, but hopefully do not need the more sophisticated and tolerant protection a measurement (or pro) amp needs to survive repeated test failures (or mistakes), and may not need the cooling (thermal management and protection) of an amp designed to be used on stage or in a test system running at high power all the time.

Many other factors, but those are some quick thoughts.

So, many words to say "maybe, it depends"... - Don
 
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Pjetrof

Pjetrof

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I cannot speak for Klippel. Your question seems simple but the answer can get very complicated because there are so many factors and variables beneath it.

Measurements often require multiple sweeps to obtain a reasonable average result and that will reduce noise. AFAIK, Klippel is focused on measuring loudspeakers, so they are probably pretty insensitive to noise but want enough power (and low enough output impedance, which tends to go with higher-power amplifiers) to drive "any" speaker without having to worry about how much the amplifier is contributing to the measurements. I'd also want an amplifier in a test system to be very robust to test errors like accidentally shorting the output when moving a speaker or pulling a wire off (open the output) when testing. Since speaker distortion is typically orders of magnitude (factors of ten) larger than amplifier distortion, having super-low amplifier distortion is probably not a big deal. That is also true in the home, of course, but chances are you are listening at lower levels than when testing a speaker. You want the test tones to be high enough to be well above any background noise; ideally you'd test in an anechoic (very quiet) chamber, but the Kipple system is designed to not require an anechoic chamber, and that means more noise in the room. Which means more power from the amplifier to rise above the noise.

Back to your question, there does not have to be a difference, and there is often a lot of overlap since a good amp is a good amp. Good performance matter for both applications, but which parts of the performance matter to you may be different than what matters in a test system. But you may weigh things (parameters) differently for a home system. If the amplifier is in the same room you might not want fans. You are probably driving a single set of speakers and can select the amp for those speakers instead of an amp to drive all speakers. If you have highly sensitive speakers like horns you may want less power and higher SNR (lower noise floor). If your speakers are not very sensitive, you sit fairly far away, and the speakers have low impedance and high phase angles (they are hard to drive), then you may want a higher-powered amplifier that can handle low-impedance loads. There are also aesthetics (looks); a home amplifier is often exposed in a console or on a shelf and you want it to look nice, or at least fit in with the rest of the components, while a test system amplifier is often in a rack with other test equipment and looks do not matter. You probably want basic circuit and speaker protection in a home amp, but hopefully do not need the more sophisticated and tolerant protection a measurement (or pro) amp needs to survive repeated test failures (or mistakes), and may not need the cooling (thermal management and protection) of an amp designed to be used on stage or in a test system running at high power all the time.

Many other factors, but those are some quick thoughts.

So, many words to say "maybe, it depends"... - Don

Thx Don
 

pjug

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Some people like to use pro amps for home audio because you can get a lot of power for low cost, and the sound is good enough. But the QSC PLX amps are not so inexpensive. The PLX1802 is about $1K from what I can find. For that money you can get March Audio's P502, for example. Similar power, similar price, cool running, and made for home hifi.
 

dezza

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I have a PLX3102.
Have owned it for about 10 years.
I used it for a bout 5 years as my computer audio system, where I sit writing this. Plenty of power which seemed to help with the lower frequencies.
I like drum and bass music. I believe it did a better job than the low power denon receiver that it replaced.
I particularly liked the separate gain controls for each channel. This made a quick volume balance possible with a sound meter.
Now it sits waiting for me to install it in my shed with am SMSL-M500 dac and some dali speakers.

The fan was too loud for me to bear, so I replaced it with a much quieter model, recommended somewhere on the net.
It is fine now.
 

Panelhead

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Seems like application related. For PA, or touring use the fans are fine. For home use their are Smart Force Air Cooling options. I used two models of the Crown Drive Core series and never heard the fans.
Currently use amps that have aluminum cooling tunnels with temperature regulated fans. Only hear the fans after turning the amps off. They run for about 10 seconds after power down. Must be a default setting.
Think smart cooling will replace big heavy heat sinks. Less weight, maybe better performance.
Classe is using an Intelligent Cooling Tunnel to cool the Delta Mono’s. Extruded aluminum honeycomb with temperature controlled fan. High surface area and low mass to heat up and coil down faster. The marketing from Classe said the amps work better under real operating conditions.
 
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Mudjock

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I have a PLX3102.
Have owned it for about 10 years.
I used it for a bout 5 years as my computer audio system, where I sit writing this. Plenty of power which seemed to help with the lower frequencies.
I like drum and bass music. I believe it did a better job than the low power denon receiver that it replaced.
I particularly liked the separate gain controls for each channel. This made a quick volume balance possible with a sound meter.
Now it sits waiting for me to install it in my shed with am SMSL-M500 dac and some dali speakers.

The fan was too loud for me to bear, so I replaced it with a much quieter model, recommended somewhere on the net.
It is fine now.
I have a CX902, which is the commercial install version of the PLX3102 and have been running it with the M500. I think you will be happy with the combo.

I agree with you about the QSC having a little more low frequency kick. I swapped out a large Rotel RB-991 and found the CX902 to be similarly resolving, but a little more dynamic. When I decided to try the QSC as a full range amp, a primary consideration was Amir's measurements on the DCA2422, which correlates to the CX702 and PLX2502 if I recall correctly. I chose to believe that the "good" channel is representative of their performance in good working condition and I don't hear anything to lead me to question that.

I've considered switching over to Hypex/Purifi for a while, but have a little suspicion that the extra power that something like the QSC amps can provide might be as important or more important than low distortion below a certain threshold.

I've been running a Samson SX2400 (rated 550 WPC into 8 ohms, 750 WPC into 4 amps) as the house amp for a DIY speaker event for about the last 4 years and recall last year when I arrived people were running to swap out the 200 WPC Adcom amp for the Samson. I just like pro amps for this purpose because they have to run 30-50 pairs of DIY speakers over the weekend, some of which may have extremely low efficiency, low impedance, or actual wiring errors and the worst thing that will happen in that event is a protection relay will trip, we can reset and get back to listening. A funny thing is that our group has found we're not really missing anything for critical listening vs. the audiophile approved amps we used to use (modified Adcom and Parasound units, Theta Dreadnaught, etc...) Maybe I'll bring the QSC or a recently acquired Ashly PE 1800 (same amplifier section as the Camco Tecton) to compare the next time the pandemic allows us to hold an event.
 

dezza

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A funny thing is that our group has found we're not really missing anything for critical listening vs. the audiophile approved amps we used to use (modified Adcom and Parasound units, Theta Dreadnaught, etc...)


I have the same opinion from my experiences.
 

alanca3

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I have used all of the variants of the QSC PLX. We use them for theatrical live sound reinforcement. I use the 1602 for very small format fills, 2402 for small format fills, and 3402 for dual 18" JBL subs. Main reinforcement is an array of up to 8 Meyer Sound UPA-1P / 2 USW-1P, depending on the space.

In terms of sound quality, they are fine. We have never observed them introducing distortion or artifacts. For comparison, in a quiet theater you can just hear the hiss of the active Meyer boxes. Not so with the PLX driven boxes. That show had 6 Meyer boxes and 12 PLX driven channels strewn about the space. I cannot tell a difference between the class H and class AB variants.

The amps are extremely reliable. We have around 15-20 in inventory, and they've been working fine for 10+ years. That's 10 years of student technicians moving them around, dropping them, etc.

With that said, they are not suitable for typical residential applications. The fan is quiet but audible at close range. The noise floor is low but just audible if you're sitting 5-10 feet from a speaker. I would use them for subwoofers though.
 
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