Review and Measurements of QSC DCA2422 Amp

[Bubu]

Four of them are driven in bridge mode to power my subs; in upper region volumes you can hear like a vibration that sync with the musicbeats that come from inside the amp, I presume it had to do with the power supply or so like you can see in the video below. Can anyone tell what that can be?

 

[Bubu]

it didn’t work to attach the video, don’t know why

 

[Peter The Greek]

Odd, i've never had issued with mine. Maybe they're vibrating at a certain frequency? or the fans revving up?

 

[Bubu]

Odd, i've never had issued with mine. Maybe they're vibrating at a certain frequency? or the fans revving up?

Can you tell how can I attach the short video?

 

[da1duc]

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)?

I'm sorry for not getting back to you sooner; lots of life happened.

So my original picture is of a newer DCA1222 version.

I tried these mods yesterday and got a mixed bag of results. The amp did power up and could work, but after shutting it down via the switch, it dumped DC on the speaker output (pop). Stupidly, I never tested the unit on 120V. Now the theory I have is that since I am running 240 split phase vs. 240 single, the AC-LO and chassis GND are not bonded, which is causing the issue. So I have some more tests to run, but I have an idea of how to fix it.

I have never seen an option for US 240V DCA, anyone else?

 

[da1duc]

I tried a quick test to shut off both phases externally, but it still popped. I might roll it back (with a faster way to mod it back) to see if the issue persists.

 

[apgood]

I'm sorry for not getting back to you sooner; lots of life happened.

So my original picture is of a newer DCA1222 version.

I tried these mods yesterday and got a mixed bag of results. The amp did power up and could work, but after shutting it down via the switch, it dumped DC on the speaker output (pop). Stupidly, I never tested the unit on 120V. Now the theory I have is that since I am running 240 split phase vs. 240 single, the AC-LO and chassis GND are not bonded, which is causing the issue. So I have some more tests to run, but I have an idea of how to fix it.

I have never seen an option for US 240V DCA, anyone else?

Yeah here in Australia 240V is single phase. I don't recall getting any pops on power on or off, but I have them connected to a Q-SYS core not directly to a preamp/processor

 

[Bubu]

Hi there,
want to bring my dca1622 to the electronic technician to modify it for bass duty in bridge mode ( populate the two missing 200v caps and replace the ten 470uf with 1000uf caps to increase power); problem is,I can‘t find anywhere the 1000uf 100v caps in 16mm diameter to replace the 470uf; on the qsc/parts website I just find a 1000uf 90v, don’t know if thr diameter is the same with the 470cap.
Can anyone help with this?
Thanks!

 

[Bubu]

Anyone?

 

[Jonas_h]

@amirm, did you ever do a "THD vs frequency" graph on this one? I would suspect it performs better than equally priced Class D "pro" amps.

 

[peng]

@amirm, did you ever do a "THD vs frequency" graph on this one? I would suspect it performs better than equally priced Class D "pro" amps.

Going by the specs., I think they will have lower THD vs frequency than say, some of the Crown audio class D pro amps such as the XLS series, but that doesn't mean it will perform better than equally priced class D pro amps as such as there are just too many such class D pro amps in the price range. I do not recall ASR measured any DCA series amps except the DCA2422, but you can do a search to find out.

The DCA2422 did not do too well, but it was dragged down by channel 1, it might have been just that particular sample, or something was wrong in that measurement. It is unusual to have one channel measured with THD+N so much higher than the other. As Amir commented:

As noted, channel 2 was fine but channel 1 was all over the place. Its SINAD (signal over noise and distortion) hit a low of 49 dB and a high of 83 dB (later in testing). There is some kind of instability there. I noticed that jiggling the speaker cable in that channel caused some variations too so maybe it is mostly the connector.