Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Discussion about old sound cards, MIDI devices and sound related accessories.

Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-14 @ 16:46

Hi everyone!

The FTL Sound Adapter is fully documented in the Dungeon Master Encyclopaedia. (See http://dmweb.free.fr/?q=node/1514, more photos at http://dmweb.free.fr/?q=node/622.)
And the Covox Speech Thing has been fully reverse engineered, as well. (Over in the CVX thread at https://www.vogons.org/viewtopic.php?f=62&t=51483 – awesome job, folks!)

How much interest is there in somewhat more accurate replicas of these devices?

So far, I've created the following PCB layouts, one for an FTL Sound Adapter replica:
FTL_Sound_Adapter_replica_layout.png

And one for a Speech Thing:
Speech_Thing_replica_layout.png

They would largely use the same components. The filter capacitor on the Speech Thing would be left unpopulated.

Furthermore, I've been able to identify all visible components on Cloudschatze's photo of the SoundJr (also in the CVX thread).
There's really nothing fancy on there, only a few resistors, diodes, PNP transistors and a big tantalum capacitor.
So with a bit of additional information that device is within reach, as well.

Any suggestions? What do you think?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby SirNickity » 2019-2-14 @ 18:45

I'm sure if you did a PCB group buy or something, some of the guys with older laptops would go for it. If you don't have any interest in being a distributor of products with meager margins, publish it to OSH Park's projects page and let people order them individually. Anyone with a soldering iron can build one.

On a similar note, I've kinda been thinking about creating an audio orphans card lately... ISA with OPL FM (I have a couple spare chips), CMS PWM, CST/DSS for a DAC, and a simple mixer. Just for fun. These old, hacked-together audio cards make for fun engineering experiments. :-) Probably not something I could distribute, because the BOM would be much higher than any rational person would be willing to pay -- assuming I had sources for the important ICs to begin with. But maybe when I get a little more practice with FPGAs.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-15 @ 11:44

My intention is to get PCBs and components for about 10 pieces each, just to prove that the designs are error-free and because that is the smallest somewhat economic batch size.
I'd then publish the design documents, package some DIY kits to recuperate the cost and leave it at that.

For the FTL Sound Adapter and the Covox Speech Thing that is easy because other people have already done all the hard work.
The SoundJr reverse engineering effort is still ongoing. Right now, this is all I have:
SoundJr_schematic_front_only.png
Mostly useless partial schematic of the SoundJr (PCB front, only)

It is entirely based on this information (text and picture):
Cloudschatze wrote: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 and 767163203, or 8A103 and 8A203 resistor array ICs. In addition, the SoundJr features software-controllable, 8-step volume attenuation. These (or similar) elements might be worth considering as part of a new design.

Image

I have an extra unit, if there's any interest in a reverse-engineering effort. Otherwise, there's a passthrough version of the SoundJr on eBay that could be looked at, and isn't too terribly priced. The listing even includes some oddly nice photos of its PCB.

Unfortunately, eBay does not keep product photos forever. Those "oddly nice photos of its PCB" would have been helpful.

I found another piece of information on an ancient Geocities page:
The SoundJr use the standard printer port data pins (#2-9) for digital audio data and the control pins (#1, 14, 16, 17) for volume control. All these output pins are also used to supply power to directly to the amplifier and volume control circuits. The output is a standard 1/8" stereo mini-jack with the same signal (mono) on each channel.

If that is true, the selection of possible audio jacks can be narrowed down to just the stereo versions.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby matze79 » 2019-2-15 @ 17:35

The SoundJR will not work with every System due do its design flaws.

If powered by LPT it may work or may not.
Not every system delivers enough current to drive a amplifier ;)


i also wanted a replica of the FTL but simply added the one Jumpwire to my Covox to get it detected.
Dungeon Master does not play very well with a Joystick :)
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby SirNickity » 2019-2-15 @ 18:47

Is there something specific that supports this rare DAC, or is it just for funsies and the sake of preservation? Just curious. I don't recall hearing much or anything about the Sound Jr.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Cloudschatze » 2019-2-15 @ 19:02

matze79 wrote:The SoundJR will not work with every System due do its design flaws.

If powered by LPT it may work or may not.

Have you tested and found an LPT port with which a SoundJr will not work, or is the criticism still conjectural?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-15 @ 19:09

The most interesting feature is its ability to drive headphones without sacrificing quality combined with software-controlled volume.
Also, I'd say that the 3mA it claims to consume, drawn from several pins combined, really aren't a lot.

BTW.: Cloudschatze, do you still have that device and would you mind taking a photo of the back side of the PCB?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Great Hierophant » 2019-2-16 @ 00:23

I've often wondered if the FTL joystick adapter really worked and Dungeon Master's PC port actually supported it. The adapter is really simple, one of the parallel port grounds is connected to the common ground of an Atari-style joystick. Then each of the five "buttons" on that joystick is connected to one of the five input pins on the parallel port. When one or more of the buttons is pressed, it sends ground to the input pin. That's the theory anyway.

Strangely, four of the five buttons are connected to a control port (output) pin on the parallel port. I don't know why they connected them like that.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Paralel » 2019-2-16 @ 04:20

I got ahold of the original designer of the SoundJr, and was able to get the software that was originally used with it. I believe I uploaded it here. But, if not, I can do that if anybody wants.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-16 @ 11:07

Great Hierophant wrote:Strangely, four of the five buttons are connected to a control port (output) pin on the parallel port. I don't know why they connected them like that.

That is because the joystick input lines need pull-up resistors and the control lines were originally implemented as open-collector outputs with pull-up resistors.

Now that I think about it:
If the parallel port in question uses push-pull outputs for its control lines, driving them low externally might damage the port.
So I should probably deviate from the original design there and put some series resistors in there.
Maybe that's why FTL did not advertise the joystick connector.

Paralel wrote:I got ahold of the original designer of the SoundJr, and was able to get the software that was originally used with it. I believe I uploaded it here. But, if not, I can do that if anybody wants.

You did.
Erm... Don't you have one of those devices, as well?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby matze79 » 2019-2-16 @ 12:24

are you sure it draws only 3ma ? we tried several types of amplifier and a headphone always was not loud enough for enjoying it..
Using a Escom 386 Notebook and some Desktop PCs.

But on my IBM PS/1 i can draw enough current for driving 2x FIFO, a Amplifier and a DAC AD7524 IC.
I forgot to connect the powercable and indeed it worked..

I'm very intressed on the windows driver.. maybe its a bit better then the Covox one ?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-16 @ 13:25

I'm still not convinced that there's an amplifier IC in there. It wouldn't surprise me if that slightly bigger PNP transistor in the SoundJr is the amplifier.
Also, please note that it draws power from several pins combined.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Paralel » 2019-2-16 @ 14:50

Benedikt wrote:
Great Hierophant wrote:Strangely, four of the five buttons are connected to a control port (output) pin on the parallel port. I don't know why they connected them like that.

That is because the joystick input lines need pull-up resistors and the control lines were originally implemented as open-collector outputs with pull-up resistors.

Now that I think about it:
If the parallel port in question uses push-pull outputs for its control lines, driving them low externally might damage the port.
So I should probably deviate from the original design there and put some series resistors in there.
Maybe that's why FTL did not advertise the joystick connector.

Paralel wrote:I got ahold of the original designer of the SoundJr, and was able to get the software that was originally used with it. I believe I uploaded it here. But, if not, I can do that if anybody wants.

You did.
Erm... Don't you have one of those devices, as well?

Yep.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-2-16 @ 14:57

Would you mind taking some pictures?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Paralel » 2019-2-16 @ 19:24

No prob.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby matze79 » 2019-2-16 @ 19:57

Benedikt wrote:I'm still not convinced that there's an amplifier IC in there. It wouldn't surprise me if that slightly bigger PNP transistor in the SoundJr is the amplifier.
Also, please note that it draws power from several pins combined.


yea i did draw power from status lines using shottky diodes with only 0,3v drop.

https://320volt.com/en/paralel-port-dij ... s-tda7050/
Also tried this, but it draws too much power to be useful.
And also Single Transistor Amp, but never was happy with audio quality or with output power.

So i'm really intressed how the SiliconSoft SoundJR will Sound.

But with rise of low power devices, maybe a little class d amp would be better ?
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby matze79 » 2019-3-06 @ 10:56

is there any progress ? i'm really intressed how they push a headphone with 3ma.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Paralel » 2019-3-07 @ 21:48

Sorry for how long I have taken to get this done. Life has thrown me a bunch of curve balls recently and I have essentially been just running around putting out fires. I will get this done as soon as I can, hopefully this weekend.

I can say part of the SoundJr design is that they specify a certain Ohm for the headphone. I don't remember the number right off the top of my head, but I will make sure I have that as well when I post the pictures. They make sure to really stress this, in bold, underlined, so I have to believe this has something to do with how it works.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Benedikt » 2019-3-08 @ 20:17

Well, it's a good thing then that the internet does not forget, right?
Paralel wrote:He produced a product that had 8 step software volume control, double the frequency range of the Covox Sound Thing, and could directly drive a 32 Ohm pair of headphone due to the integration of a simple amp, and even a sleep-mode so it would stop drawing power if you were running off of a laptop battery, all working off a measly 3 mA provided by the LPT.

Anyway, I have 32 Ohm headphones, so I'll be fine.
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Re: Replicas of Covox Speech Thing, FTL Sound Adapter and SiliconSoft SoundJr

Postby Paralel » 2019-3-08 @ 22:15

Agreed. :happy:

I have written so many things, on so many forums, over so many years, I doubt I remember .0001% of it.
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