wedanced
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San Francisco

I have been using ableton to make music largely now. One of the things I miss from my hardware days is the raw sounds I used to get from my recordings. I have been doing some research on older sound options that were available during the earlier days of playback on computers from the 80's through the 90's and I have been trying to emulate some of coloring from those devices.

Anyways long story short I was looking at the old Covox speech thing DAC clones. They are easy to build with very few parts but are designed to be plugged into the old printer ports. I was wondering if it might be possible to adapt that design for USB so i can plug it into my modern computer.

I dont really know too much about usb and parallel printer ports and all that so I just searching for info.

The Covox speech thing could apparently support higher sample rates but were limited by the software of the time. I just want to see what is possible with something like this.

any ideas guys?

nitro2k01
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Sweeeeeeden

Answer, not really. USB is very different from a USB port, and it's not really suitable for simple interfaces like that, compared to the LPT port. You might get similar results from using a bit crusher, though. Try experimenting with Decimort, which is one of the probably few high quality bit crushers which are not focused on just destroying the sound completely. Try something like 8 bits, frequency around the 11k-22k range, filter pre, LP, filter frequency to your liking, somewhere around half the sample frequency.

http://www.d16.pl/index.php?menu=203

Another option might be to get an Arduino (if you don't have one) and try building a similar circuit to the covox and attach it to one of the digital ports. Obviously, then you would have to synthesis code on your own. That's not what you were asking for, but might be  an interesting adventure.

yogi
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Jelly Stone park, MD USA

As you may know the Convox is a simple R2R DAC with parallel inputs.
What this means is there is a string of resisters with tap points along the  series. Each bit from a parallel bus connects to one of the taps, so if the bus is driven with a Byte/Word value the resisters sum the "1"s for a output voltage, somewhere between 0 & 5V . More "1"s, the higher the sum voltage will be.
To use this DAC on USB (serial) you would need something like one of FDTI's chips and a latch to hold the current sample. In addition you need the driver softs to handle sending the samples out at a constant rate to reproduce the wave sound. not easy with USB (USB transfer rates depend on the mode) or use a uC to receive the samples in a FIFO and latch them on to the DAC.
All do-able but quickly becomes very complicated.
Yogi

wedanced
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San Francisco

thats about what i thought. blaaaah!!!
too bad. I think building all of that then coding the driver is waaaaay more work then i am willing to do.

Arduino would be interesting as i have seen some people already do similar projects.

I think what i will do is probably just build a speech thing download the drivers and hook it up to my old compaq laptop. I can sample sounds on that thing and record from the speech thing using fasttracker hooked up to my modern computer.

the compaq has an older ESS Audiodriver. the ess apparently records and plays back in 16-bit stereo but from my experience it always colors the sound and even has that nice crunchy fade out while volume of a sample is approaching zero. I will just make do with that until i can build a covox.

herr_prof
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Isnt that what basically the audio output on a raspberry pi is?

wedanced
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San Francisco

I am not sure. I dont have any knowledge about the pi other than the basic idea that it is a cheap programmable computer that runs off a SD for a hardisc. I dont know anything about what kind audio it can output. I was thinking about getting one just to fool around with tho smile

my next thoughts on the matter is that maybe i could use an older sound card via usb like soundblaster 16 or something.
There are usb to isa adaptors.
http://www.arstech.com/item-USB-2-0-to- … 2isar.html

At this point i am thinking i am just hitting on mental masturbation rather than anything useful tho.

herr_prof
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From what I undestand the pis audio output is just using the gpio pins ala arduino to make sound.

ant1
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uhajdafdfdfa

dunno how likely you are to find drivers for an ISA sb16 for win7 etc, not sure if a soundcard will even work on that usb adapter

and the sb16 doesn't sound that "gritty" anyway


one thing you can do is run FT2 / digistudio / st3 in PC speaker mode (edit: or now that i think of it, COVOX/DSS mode) in dosbox, load stuff up in there and play it back, and sample the output (or learn to track in dos LAMER!!), if you aren't worried about HARDWARE PURISM this can make some gritty sounds and each of the trackers sounds totally different due to the way they coded pc speaker output

Last edited by ant1 (Nov 19, 2012 6:06 am)

AuburnKitsune
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California

guys wtf am i is yous talkings abputsss lsdjss foreversss fuks

sorry im delirious

Last edited by AuburnKitsune (Nov 20, 2012 3:24 am)

boomlinde
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Sweden

Maybe you can get a USB sound card, rip the DAC off and replace it with a serial->parallel chip going to a series of 8 dirty old resistors. But I guess the DAC is part of a single multipurpose IC... Easiest way to go is probably getting an ADC of some sort and then build your resistor series DAC on the other end, and then just route audio through it.

egr
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Abandoned on Fire

Oh, not the Covox I was thinking of. nvm

wedanced
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San Francisco

hmmmmmm.... Well i wanted an external soundcard option for when i play live. It would be nice to just plug and play and to get some dirty oldschoolish sounds while i bump my ableton jams but it really sounds easier to just record some lower sample rate files and use those at this point sad

Herr_prof: well it would probably be easier to just do it with Arduino wouldn't it? i mean i couldn't really output from ableton in the the PI and out of its gpio pins could i? I mean i dont know nothing about nothing tho so correct me if i am wrong.

ant1: I am using ableton, i seem pretty not purist at this point. I can learn to deal and just sample everything. I am already cheating aren't i wink
lol i actually create a lot of my patches using simpler and samples i take from mods i have worked on with older computers. I am actually pretty heavy in to sample synthesis due to all my time with LGPT tracker and nitrotracker. I am a total control freak tho. I always have to make my own samples otherwise it really ends up getting on my nerves and i feel like i am cheating myself.

boomlinde: That sounds like a good idea if i understand what was said. The first idea is replacing the DAC circuit of an already built USB soundcard with the covox circuit. The issue is that they integrate the circuit of the usb translator/blah blah blah chip and the DAC into one chip rather then having a separate DAC chip handle it? would it be a possibility too that even if you found a soundcard with a separate DAC chip it might not have the 8 points required for the covox circuit to work anyways? i can look around tho and see what soundcards are doing these days hardware wise.

I did find some DIY ADC projects online but after the DAC we would run into the whole USB requirements again putting us at square one again i think.

egr must be thinking of the gameboy master covox tongue

wedanced
Offline
San Francisco

holly shit guys. i think i just found what i have been looking for hardware wise. It can use the same r2r circuit that the speech thing uses. it would just need some programing to output samples and act as a soundcard otherwise it is all there.

http://blog.makezine.com/2011/02/15/dac/

It would be waaaaay easy to build then all the other options as far as i can tell.

and if I am thinking about this correctly you could get stereo sound via making another 8 point r2r and hooking those up to the extra points. BAM BITCHES. dual 8-bit resolution play back outputs. 

Any of you into this idea and are good with the programing tongue
my programing skills are piss poor.

It would mean authentic covox speech thing sounds for your modern computer with the added bonus of stereo! *nudge nudge wink wink*

looks like arduino is the way to go!

the covox r2r circuit!

pretty much everything nitro said tongue

Last edited by wedanced (Nov 21, 2012 4:20 am)

wedanced
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San Francisco

and of course little-scale already had been messing around with this stuff.

http://little-scale.blogspot.com/2011/1 … g-for.html

ant1
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uhajdafdfdfa

i think what boomlinde is saying earlier is that you take a and ADC and a DAC, wire them together , and then it will have analogue on both sides, input and output, and you just put it in a loop on your soundcard, audio comes: out of pc -> ADC -> DAC -> in to pc

no usb required smile


(the DAC coudl be one you built from resistors, and just use a stock ADC, i think)

Last edited by ant1 (Nov 21, 2012 6:46 pm)

yogi
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Jelly Stone park, MD USA

Good Vid! Take a look at this Polish site http://atariki.krap.pl/index.php/Covox Instead of connecting to an Atari, just use an Arduino. You'd have USB with 4 channels of 8bit sound using 14 pins. I think there are that many digiPins on an UNO or use the new larger Arduino. Lotharek had PCBs at one time but not on the site now, could try contacting him direct. Very compact SMT design, would work well as an Arduino shield.
Course there is the software to deal with. Talk to Little Scale, he may have already done something exactly like this! He's a MaxLive guru so he would have the answers on how to do this in Alberton I think.