Digital input & output on outboard

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tommia

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I use those cheap spdif to analog convertors (look at the link) connected to my lynx convertors (AES/EBU) to insert old effectprocessors and reverbs in my daw. This works great, but the adc and dac in those 30+ old processors are noisy, so I was wondering if I could modify those outboard gear and omit their ADC & DAC convertors and make a direct digital input and output. I guess syncing will be the problem.


 

living sounds

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IMO the converters in old high end gear are very likely to be of higher quality (according to ears, not necessarily for some psychoacoustically irrelevant measures) than cheap modern stuff. I actually prefer some old high end converters to rather pricy modern ones...

It should be possible to add digital IO and skip the converters altogether, but it won't be easy. Depending on the device in question you might even run into issues like non-standard sample rates that will force real time SRC (never transparent). The older the device the harder it will get, and there is the added issue of damaging old valueable gear (for which documentation might also not be availible).

Also, in some devices the converters may be part of the "sound".

Which processors would you like to upgrade specifically?
 

tommia

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I was thinking of Yamaha spx 90, Roland Dep 5, and stuf like that. More the cheap ones. I love those, but sometimes esp. the SPX is really to noisy for today's standards.
 

Newmarket

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You'll need sight of the relevant schematics and converter ic data sheets to progress on this.
If they illustrate how to implement an SPDIF or AES3 Input / Output then it might be practicable.
If they use their own proprietary chipsets (I'm thinking Yamaha particularly here) then the data might not be readily available now but worth a look.
 

living sounds

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I was thinking of Yamaha spx 90, Roland Dep 5, and stuf like that. More the cheap ones. I love those, but sometimes esp. the SPX is really to noisy for today's standards.

Me, I really wouldn't bother. Internal sample rates are 31.25 khz and 32khz respectively. So SRC would be mandatory.

The BB PCM54HP in the Roland unit is actually a very good monolytic 16 bit R2R DAC. Properly implemented I wouldn't mind listening to music through it.

Also, there are noise gates. ;-)
 

Newmarket

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What does SRC mean?

The SPX uses the same DAC as the DEP 5. No Fancy Yamaha chips there.
Thanks for posting that.
I'm confused by the schematic / parts detail on the ADC / DAC there.
It seems to list the same PCM54HP for both (IC114 / IC115) but the device is a DAC only ?
 

Tubetec

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The SPX 1000 might be worth a look if you can find one going cheap , it has everthing the SPX90 has but better , more parameters to adjust ,more different kinds of effects , better convertors and quieter 44.1k/16bit internal processing .
Its my guess most of the noise you hear in the SPX90 will still be there no matter what convertor you use .What it spits out is badly distorted in any case , thats not distortion inherent in the conversion but the internal processing itself.

Gating the output of the SPX in the DAW , like previousloy suggested , is the best way to go , all the noise and distortion is an inherent part of the sound , but it needent be droning away in the backround all the time either .

Going back to the days of 12 bit samplers like the Akai S950 , the processing created artifacts in the sound ,sometimes that simply sounded bad , on ocassion though it could add a sparkle to something otherwise a bit lifeless . Pitchchanging down in particular brings up a grainy texture that sometimes works , same on the SPX's .

SPX2000 does sport USB/Digital audio i/o , Im not sure how well it recreates the dirt of the original low bit units though.
 

tommia

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From the sound samples I could find on the net, the spx 1000 is to transparant to me, but I could be wrong. If so please give me your opinion.
It seems that sample rate conversion is becomming not so difficult these days: CS8421 | Cirrus Logic
I have little to no experiance in the Dac and Adc domain designing wise. Any ideas how to start are welcome. From what I find so far Cirrus has the simplest solutions also for Dac's: CS8416 | Cirrus Logic
 

tommia

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Ok. I followed more or less the advice from Tubetec and bought an SPX 990. It will not replace my spx90, but boy there are some great sounds in that box!
 

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