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Re: Reversing the Disney Sound Source

Posted on 2017-12-09, 04:01

shock__ wrote: Amplifying the noise helped ... 72Hz seems to be the frequency of the noise I'm getting (7524 based DAC) Ok, can anyone think of any common source of a similar frequency, or a harmonic of one, perhaps a fractional harmonic even?

Re: CVX-2 : covox adapter

Posted on 2017-12-04, 21:20

Yeah, but has anyone tested to see what the actual cut off for the frequency range for the R-2-R covox is? Can it actually output a 22.05 KHz frequency? The Covox has no filter at all (and the CVX4 also has a no-filter setting). So theoretically there is no cutoff. I think the easiest way to verify …

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 21:22

Yeah, but has anyone tested to see what the actual cut off for the frequency range for the R-2-R covox is? Can it actually output a 22.05 KHz frequency? I'd actually suggest maybe 15 KHz as a test. None of us here can probably hear into the 22 KHz range. If someone in their early to mid 20's can …

Re: Reversing the Disney Sound Source

Posted on 2017-12-03, 21:13

If the DSS is active, but completely silent, so set to play a string of nulls or something (What I'm thinking is that its actively processing stuff, but what its told to process produces no sound, not sure if I phrased that correctly) [I don't know if this is possible] is it perfectly quiet?

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 21:06

It has roughly double the frequency range of the discreet R-2-R ladder Covox design What makes you say that? Technically, the only limit for the frequency range of a Covox is the speed at which the CPU can bang out the samples through the printer port. I don't honestly remember the calculation, but …

Re: CVX-2 : covox adapter

Posted on 2017-12-03, 18:48

As I mentioned earlier in this thread a Covox Speech Thing clone, the "SoundJr" uses: "767163103 and 767163203, or 8A103 and 8A203 surface mount resistor array ICs" and it has the following features: "Level Control: 20 dB/ 8 Step software control Frequency range: DC to 15KHz Sample Rate: Set by …

Re: OPL2LPT

Posted on 2017-09-15, 04:47

Since the Digispeech Port*Able Sound Plus is based on an ESS chip, which, if I'm not mistaken, emulates a soundblaster in hardware, couldn't you just treat it like a soundblaster but instead of using the standard port 220, you use the port for LPT instead? I'm sure its not that simple, I just don't …

Re: OPL2LPT

Posted on 2017-09-10, 21:35

That Digispeech Portable Sound Plus looks absolutely awesome. Adlib & SB? Sign me up! It uses an ESS ES688P. It's capable of: Stereo (and Mono) playback, 16 or 8 bits per channel Sampling rates from 4 Khz to 44.1 Khz Supports DVI (IMA) ADPCM, OKI ADPCM and SoundBlaster ADPCM compression and …

Re: CVX-2 : covox adapter

Posted on 2017-09-10, 15:46

Wayne Foletta (Silicon Shack / SiliconSoft) produced a neat little LPT DAC known as the "SoundJr" back in the late 1980s. It's not as advanced as some of the designs being discussed, but has a few interesting features. Instead of discrete resistors, this device employs a pairing of either 767163103 …

Re: CVX-2 : covox adapter

Posted on 2017-09-10, 15:13

That's more than doubled the covox-speech-thing which cut's of a 7khz afaik. Yeah, from what I have read, the best guess, without anyone having opened up one of the Speech Things speakers to look for a low-pass cap, is that, by ear, its cut-off is ~7-8 kHz, so the SoundJr. has about double the …

Re: OPL2LPT

Posted on 2017-09-10, 15:07

Any idea where the noise is coming from? There should be a relatively finite number of sources, it might take a little while, but it can probably be picked apart until its located. I'm starting to wonder if a metal enclosure that is tied to ground would shield the dongles from the tremendous EMI …

Re: CVX-2 : covox adapter

Posted on 2017-09-10, 05:20

Also, any benefit to making a 9-bit DAC over the standard 8-bit DAC that the Covox had? The .1% tolerance resistors that are being used are nearly twice as tolerant as what is needed to make a 9-bit DAC (and nearly 4 times as tolerant as what is needed for an 8-bit DAC, which is why 1% and even .5% …

Re: CVX-2 : covox adapter

Posted on 2017-09-10, 02:39

Has anyone popped open a Covox Speech Thing included amplified speaker to see what is is in there? Or is that impossible without destroying it? I'm curious to know if they put a low-pass filtering cap in there, etc... so we know what their intended cut-off for it is meant to be.

Re: CVX-2 : covox adapter

Posted on 2017-09-09, 07:03

Success! The ZIP provided by the creator of the hardware appears to be essentially a file dump of what they had left file-wise for the SoundJr, but all the pieces seem to be there. I uploaded it in a post to the Vogons Driver Library thread if anyone wants to download it.

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