CD turntables how do they work?

[Audioagnostic]

For those unfamiliar with the technology.
These are very cool devices meant for djs. You can play a cd, make loops, change the pitch, scratch, play music backwards.

I recently bought a pair of Pioneer cdj 1000mk3 and use the digital out to feed my dac. Sounds excellent but it is a nice toy as well...

When you load a cd it starts playing immediately but it takes some time to display the full waveform of the whole song. So, I presume there is some digital storage. But how is all the sound manipulation done? Is this all in the digital domain and does my dac do the final conversion to analogue?

Or are there subsequent adc and dac steps inside the machine?

This is just academic interest, I am happy with it. My Pioneer sounds fine and is built like a tank. Very forgiving for scratched disks as well. Bit large but it looks very cool and anachronistic next to my tiny dac.

Any links to sites that help me understand the tech inside these players is welcome!

The pic below has one of my machines, here still hooked up through its analogue outputs.

 

[AnalogSteph]

But how is all the sound manipulation done? Is this all in the digital domain and does my dac do the final conversion to analogue?

Pretty sure that's what's happening. We're talking the early 2000s, not the digital stone age.

Any links to sites that help me understand the tech inside these players is welcome!

Technics SL-DZ1200 Direct Drive Digital Turntable Manual | HiFi Engine

www.hifiengine.com

Pioneer CDJ-1000 Compact Disc Player Manual | HiFi Engine

www.hifiengine.com

Yup... two DSPs and an FPGA in there.

LOL, Technics used the actual ICs from their direct drive turntables (AN6675/AN6680) to drive their fake one. Makes sense, but it's still hilarious.

 

[DVDdoug]

Or are there subsequent adc and dac steps inside the machine?

There's no need for any extra ADC or DAC. It's all done digitally, with a DAC at the end as usual. Modern CD drives run at more than 10X speed so it doesn't take long to "rip" enough data to start manipulating it. And once you've got the digital audio data, speed change, or reverse, is pretty easy. It gets complicated if you want to manipulate speed and pitch independently but that's not "analog-like".

 

[Audioagnostic]

@AnalogSteph , thanks! Yes I have seen this clip, it was in fact the reason I wanted to buy one. The Technics are still at least 400 each, to much for a toy I will bore of and put where my other cd players rest... The Pioneer was, as I understand, the club standard in its day.

 

[Audioagnostic]

@DVDdoug , thanks! It is a magical machine to me, there must be some computing power inside.

It is able to separate pitch from tempo if you engage the "master tempo" switch. You can change the speed while maintaining pitch.

There is also a version that takes dvds. You can scratch images with that one. I am tempted...

 

[restorer-john]

Yes I have seen this clip, it was in fact the reason I wanted to buy one. The Technics are still at least 400 each, to much for a toy I will bore of and put where my other cd players rest... The Pioneer was, as I understand, the club standard in its day.

I bought the SLDZ brand new to play with back in the day, but although it was gorgeous to look at, it was a terrible player. I also had a the Denon DNS-5000 which absolutely blew the Technics out of the water for basically everything except looks.

I sold the SLDZ after about a month and didn't really lose any money. They really aren't worth owning these days, unless you want it as an ornament.

 

[drmevo]

Has anyone owned or used the Technics DZ1200 mentioned above? I…kind of want one…just for playback, to go with my 1200GR. Who knows, maybe my kid would have fun with the DJ features.

Someone is selling a couple locally fairly cheap (compared to eBay prices anyways). But, it would have to be a good player/transport to be worth it. If it’s mechanically noisy or something like that then I’d pass.

 

[restorer-john]

Has anyone owned or used the Technics DZ1200 mentioned above? I…kind of want one…just for playback, to go with my 1200GR. Who knows, maybe my kid would have fun with the DJ features.

Someone is selling a couple locally fairly cheap (compared to eBay prices anyways). But, it would have to be a good player/transport to be worth it. If it’s mechanically noisy or something like that then I’d pass.

I owned one back in the day from brand new. It was by far the best looking and nicest finished "DJ" CD player, but was dreadful for actual DJ type use. It sounded perfectly good playing a CD, but all the effects, were just an audible mess. I also had a pair of Denon DNS-5000s. Now they were incredible, you could play two tracks at once off the same disc and do crazy stuff with it.

I ended up buying a pair of smaller Denons and a matching mixer for our 8 year old when he was taking an interest in DJing, but things moved rapidily to solid state (no CDs) and USB/Computer with the 'player' being merely a controller.

I never bothered with the SPDIF out as the converters were more than good enough for CD.

Beware the Technics LCD in the centre, it is small, hard to see and fails- it's 20+ years old now.

 

[drmevo]

I owned one back in the day from brand new. It was by far the best looking and nicest finished "DJ" CD player, but was dreadful for actual DJ type use. It sounded perfectly good playing a CD, but all the effects, were just an audible mess. I also had a pair of Denon DNS-5000s. Now they were incredible, you could play two tracks at once off the same disc and do crazy stuff with it.

I ended up buying a pair of smaller Denons and a matching mixer for our 8 year old when he was taking an interest in DJing, but things moved rapidily to solid state (no CDs) and USB/Computer with the 'player' being merely a controller.

I never bothered with the SPDIF out as the converters were more than good enough for CD.

Beware the Technics LCD in the centre, it is small, hard to see and fails- it's 20+ years old now.

Thanks, that's good to know. It would be cool if these came with a remote but makes sense that they don't, given their original use case. The LCD is the other drawback, can't see it while seated or anywhere other than looking straight down at it. Although some companies have made conversion kits in the past to make it adjustable at different angles or use your phone instead, I'd want to keep it original.

If I can talk the guy down below maybe $175USD it might be a cool piece of gear to own.