The American Audio Q-D5 has been my weapon of choice for the last year. It’s a middle-end DJ mixer with your standard mixing features, plus an optical crossfader that’s top notch for scratching. It’s a great buy for the price, and my only complaint with it is that the sound quality isn’t quite audiophile grade. I’ve never noticed it while DJing at events, but in the comfort of my own home, it’s much more noticeable.
I’ve heard in the past that replacing the op-amps in audio equipment can drastically improve the quality of the sound coming out of a device. With that in mind, I decided to peer into the innards of my mixer:
Towards the right in the above image, you can see a pair of op-amps:
The one on the left is a JRC 4556AD, with a JRC 4558D on the right. The 4556 and 4558 are common op-amps found in consumer grade audio equipment, but they’re not designed specifically for audio. It looks like the 4556 is used for the master volume control there, and the 4558 is used for the headphone volume. Only two op-amps - I could replace those no problem, right?
After lifting up the rest of the top, I saw this:
It turns out there’s actually 3 separate PCBs which do the audio routing/processing, with 9 op-amps in total. And silly me, after roughly tracing the circuit, it makes total sense: There’s 2 op-amps for the phono preamps, 2 for the channel gains, 2 for the volume faders, 1 for the headphone volume, 1 for the master volume, and 1 for the mic volume. Now, I wouldn’t necessarily have to replace all nine of these op-amps to get a boost in the sound quality, but I think I’d still have to replace seven to stop the audio from getting degraded by one of the plain-jane JRC 4558s. That quickly killed my hopes of getting a cheap mixer upgrade.
One interesting thing I spotted is that each PCB was stamped with a date, all of which seemed to be from different years. For example, here’s the bottom of my crossfader:
I bought this mixer in 2006, but the crossfader was manufactured in 2001. (It’s a damn good crossfader though.) In fact, the whole mixer looks like it may have even been hand assembled.
It’s a shame that it’ll be too much work (and too risky) to upgrade the op-amps in my mixer, but it was neat to see to see what goes on inside a DJ mixer. Enjoy the pics!