Review and Measurements of QSC DCA2422 Amp

[Willem]

The French test of the 2x350 watt Yamaha P3500s is here: https://www.homecinema-fr.com/forum...mpli-yamaha-p3500s-mise-a-jour-t30056383.html
As for trigger inputs, I faced a similar problem, because the on/off switch of my Quad 606-2 is on the back of the unit. It does not have a trigger input, nor does my ADI-2 have a trigger output. I am now successfully using a cheap master-slave power strip. It senses that I turn on the ADI-2, and then turns on (and off) a string of other units, including the power amp. The only issue was that the ADI's power consumption is too low for the master sensor, so I combined the ADI-2 with my always on Chromecast Audio because their joint power consumption is just enough for the master's sensor. It works a treat without complex modifications and for little money. A rough calculation showed me that it will earn itself back with a slightly reduced electricity bill in about a year. That is one more little step in reducing my energy footprint, even if in this case only a very little one.

 

[Verdinut]

I work in cinema and have installed hundreds if not thousands of these. The DCA line has been the industry standard amp for nearly two decades. It has a rep for reliability, excellent performance and price point. Based on the front panel with the old cursive QSC logo you have a pretty old unit which has probably served a long tour of duty. These amps work 14hrs/day, 365 days year, playing soundtracks in hot dusty projection booths that pump air filled with popcorn grease. So I’d be inclined to give channelA the benefit of the doubt.

I know this is an old thread, but I just wanted to mention that I'm operating 4 DCA series amps in my HT system, three DCA 1222 actively bi-amping my 3 front channel speakers, and one DCA 1824 to drive the left and right SURR and BACK SURR speakers.

One important quality of the DCA series amps and other QSC power amps, apart from their excellent specs, is that you can't blow them.

Here is a photo of my setup:

 

[Dialectic]

I know this an old thread, but I just wanted to mention that I'm operating 4 DCA series amps in my HT system, three DCA 1222 actively bi-amping my 3 front channel speakers, and one DCA 1824 to drive the left and right SURR and BACK SURR speakers.

One important quality of the DCA series amps and other QSC power amps, apart from their excellent specs, is that you can't blow them.

Here is a photo of my setup:View attachment 112783

Nice photo. What loudspeakers are those?

 

[Verdinut]

Nice photo. What loudspeakers are those?

Thank you!

Those loudspeakers were designed by myself. The three front speakers are actively bi-amplified and a 4 channel QSC DCA 1824 is used to drive the surround and back surround loudspeakers.

Here is a detailed description of the components in my HT:

SYSTEM: MARANTZ SR5011, 3 QSC DCA 1222 AMPS. DRIVING THE FRONT CHANNELS IN ACTIVE BI-AMP CONFIG.
QSC DCA 1824 (4 CH. AMP.) FOR SURROUND CHANNELS, OPPO BDP-95, OPPO UDP-203, SONY UBP-X800, REVOX B77, TEAC AN-80 (NR),AUDIO-TECHNICA AT-LP1240, SHURE M97XE, HITACHI HCA-8300, PANASONIC TH-50PZ80U, ROKU PREMIERE +, FURMAN PS-8R, APC H15
FRONT LEFT, CENTER & RIGHT SPEAKERS: DAYTON RSS390HF-4 SUB IN EACH CABINET CROSSING OVER TO 2 PEERLESS P830991 AND 1 AIRBORNE RT-4001, QSC XC-3 ACTIVE CINEMA CROSSOVERS (SUB-MIDRANGE)
ENCLOSURES: 7.8 CF DUCTED PORT (OWN DESIGN)
SURROUND L & R AND SURROUND BACK L & R: SB ACOUSTICS SB15MFC30-8 WITH AIRBORNE RT-4001
CABINETS: 0.38 CF DUCTED PORT (OWN DES.)

 

[proj964]

Wow. What an interesting setup. Are the electronics in their "normal" position? Do the cooling fans cause a lot of noise? And I have to ask if the QSCs meet your sound expectations?

I assume the color rectangles are acoustic baffles? Also DIY?

 

[Verdinut]

Wow. What an interesting setup. Are the electronics in their "normal" position? Do the cooling fans cause a lot of noise? And I have to ask if the QSCs meet your sound expectations?

I assume the color rectangles are acoustic baffles? Also DIY?

Thank you!

I am sitting at about 6 feet from the amplifiers, so I am not bothered by the fan noise of the 3 DCA 1222s. But the 4 channel DCA 1824 is a bit noisier because the fan has to cool four output stages in the same chassis size instead of two. However, when music is playing, I don't hear the fans as they don't have to rotate fast at the SPL I listen to.

The QSCs definitely meet my expectations. I chose them because of their excellent specs and their reliability. One of my acquaintances plays in gigs, and of all the amps he has been using in his numerous gigs, QSCs are the only ones he hasn't been able to kill.

The color rectangles are just carpet samples which I got for a very reasonable price at a carpet store. They do the job.

What do you mean by your question as to whether the electronics are in their normal position?

 

[infinitesymphony]

One important quality of the DCA series amps and other QSC power amps, apart from their excellent specs, is that you can't blow them.

Yep, whenever I sneak a peek at the racks at smaller festival gigs, 9/10 times they're loaded up with QSC power amps. They seem to have gradually replaced Crown over the last few decades.

 

[proj964]

What do you mean by your question as to whether the electronics are in their normal position?

Do the electronics sit in the position shown in the photo; between you and the speakers/tv? I assume the photo is taken from about the listening position.

Oh, and using the carpet samples--brilliant!

 

[Verdinut]

Do the electronics sit in the position shown in the photo; between you and the speakers/tv? I assume the photo is taken from about the listening position.

Yeah, my listening position is about 6 feet away from the console.

 

[da1duc]

So does anyone here have a QSC DCA amp that is setup at 240V? Looking at the schematic it looks like it should be a simple change but would love to do some confirming before I try it.

Picture of the rack (WIP):

 

[apgood]

So does anyone here have a QSC DCA amp that is setup at 240V? Looking at the schematic it looks like it should be a simple change but would love to do some confirming before I try it.

Picture of the rack (WIP):

They can be bought configured for 240V input. All mine are 240V as that's the standard voltage here in Australia. Assume you could place an order for the 240V version even in the US.

Not sure what would be involved in converting a 120V version to 240V.

 

[Verdinut]

So does anyone here have a QSC DCA amp that is setup at 240V? Looking at the schematic it looks like it should be a simple change but would love to do some confirming before I try it.

Picture of the rack (WIP):

I suggest that you contact QSC, but I doubt that you will be able to use them on a 240V line. They use a switching power supply but it is clearly specified on their back that they are to be used on a 120V line.

 

[da1duc]

Contacted them and got the "Don't touch it" response buy new. @apgood would you be willing to crack one of your open and post some high res images. I think I figure out how to do it but would love some examples before I do it. Reviewed the schematics, they double the 120V before the switch mode. My goal is to feed them all with 240V as it simplifies my setup.

So can confirm that you can gang pin 2 and pin 6 for multiple amplifiers to have them turn off. You will need a relay that has a NC connection, turn that relay on with the trigger from your pre-amp. Nice thing is it looks

 

[apgood]

Contacted them and got the "Don't touch it" response buy new. @apgood would you be willing to crack one of your open and post some high res images. I think I figure out how to do it but would love some examples before I do it. Reviewed the schematics, they double the 120V before the switch mode. My goal is to feed them all with 240V as it simplifies my setup.

So can confirm that you can gang pin 2 and pin 6 for multiple amplifiers to have them turn off. You will need a relay that has a NC connection, turn that relay on with the trigger from your pre-amp. Nice thing is it looks

Might be able to do it over the long weekend. Just depends on how much kids free time I get

 

[da1duc]

So here is what I am looking for. This is a 120V version of a 1644.

 

[apgood]

So here is what I am looking for. This is a 120V version of a 1644.

Ok. Might get time later this week.

 

[apgood]

So here is what I am looking for. This is a 120V version of a 1644.

This is a 240V version of a 1222. It is a fairly old one as it has the old style QSC badge on the front.
The board layout looks a bit different to your photo. In particular that bridge for 240V vs 120V seems to be missing is yours. If you know how to convert a 120V to 240V then I'd be interested too.
Do you know if your 1644 is an old version or more recent (i.e. has the blockier QSC DCA logo)?

 

[Peter The Greek]

A quick update. I want to thank Amir for testing this amp (yes it's mine). It is a used unit bought sight unseen on eBay and shipped directly to ASR. I replaced the fan with a Noctua NF-A8 fan connected through a 220 ohm, 2 watt series resistor; it is very quiet now. I also built a 12vdc relay box to control the DCA2422 power from the pre-amp 12v trigger out signal through the power amp DataPort. BTW, the inside of the box had a lot of dirty, large dust-bunnies that needed to be given a new home. I didn't use the speakON connectors but the available screw terminal for the speaker wire connection. The unit is functioning very well.

Hey, I'm in the process of doing this mod now. I'm measuring around 8.7v on the raw fan output. Do you know if it's variable voltage? Ie does it increase as the load/temp increases?

 

[Verdinut]

What I understand about the variable speed cooling fan:
When I turn on a DCA series QSC amp, the variable speed fan rotates fast and slows down within less than 2 seconds. It is a fan that is designed to operate at various voltages, and its rpm is voltage dependent. This rpm speed will vary according to the internal and ambient temperatures and the power output demand.

 

[Bubu]

So does anyone here have a QSC DCA amp that is setup at 240V? Looking at the schematic it looks like it should be a simple change but would love to do some confirming before I try it.

Picture of the rack (WIP):

So does anyone here have a QSC DCA amp that is setup at 240V? Looking at the schematic it looks like it should be a simple change but would love to do some confirming before I try it.

Picture of the rack (WIP):

Hi, I have some 240V dca too,can I help?