DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

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Chipnetics
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DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by Chipnetics »

Hi all, Chipnetics here - creator/seller of the SyncBaby + PlayBaby, DSUB dongles for Nintendo/PlayStation.

A couple weeks ago I released another DSUB dongle, this time for the Dreamcast (called the PlayBaby). I thought I'd share some details with the shmups community.

DreamBaby is a compact and efficient Sega Dreamcast AV Multi-out to DSUB (with 3.5mm audio-output) adapter to output 15Khz (240p) and 31Khz (480p) video. It is unique in that it can output both RGBHV, and RGBs, by using a sync combiner circuit. The Hsync and Vsync are taken directly off the Dreamcast GPU with Csync generated from these signals. This results in being able to use 15Khz or 31Khz in both RGBHV mode and RGBs mode; which is not otherwise possible on the Dreamcast!

Purists will note that Dreamcast does output Csync on the AV Multi-out on pin 10; however, this specific CSync signal is generated from an encoder (and not via the GPU) resulting in a poorer image, compared to that from a sync combiner. Also this specific Csync signal is actually disabled in 31Khz mode!

Some features of this product:
  • No external power required
  • Change between 15Khz and 31Khz output via jumpers
  • Change between RGBHV and RGBs via jumpers
  • Female D-Sub (15-pin) video output
  • 3.5mm audio jack output
  • Premium Kemet 220uF caps and passive components
  • Premium sync-combiner transistor (300Mhz)
  • High quality PCB, ENIG plated; in matte black finish
The DreamBaby can be purchased off Tindie here . I'm also offering a discount on the SyncBaby and PlayBaby that you can bundle with purchase. Thanks all! :D

Feel free to share some ideas for other systems you may want to see, as I've done the core systems I'm personally interested in.

Obligatory photos....
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NoAffinity
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by NoAffinity »

This is awesome! Definitely scratches an itch, being able to put out 240p or 480p as rgbs or rgbhv. Great work!

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Ryeno
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by Ryeno »

Did you measure the output with a scope? From what I understand all Dreamcasts output .8vpp instead of .7vpp and require an inline 10 ohm resistor to fix the issue.

Are those aluminium polymer caps? If so I would replace them with aluminium electrolytic caps because they have lower leakage current and that's better for decoupling.
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Unseen
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by Unseen »

Chipnetics wrote:Purists will note that Dreamcast does output Csync on the AV Multi-out on pin 10; however, this specific CSync signal is generated from an encoder (and not via the GPU) resulting in a poorer image, compared to that from a sync combiner. Also this specific Csync signal is actually disabled in 31Khz mode!
Are there serration/equalization pulses in your generated CSync signal in 15kHz mode?
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NoAffinity
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by NoAffinity »

Got mine yesterday. Been playing around with it this morning. It definitely puts out a clean signal, via rgbhv or rgbs. Replacing my retro-bit cable with this adapter + a proper vga cable w/ ferrites and a separate 3.5mm audio cable eliminated a small bit of noise I was getting in the image, with the retro-bit cable.

The claims of outputting 240p 15khz are a bit mis-leading, though. I've been playing Capcom vs. SNK2, and with jumpers configured for 15khz RGBHV and RGBS, it is still a 480i game.

I've been playing with output simultaneously going to a CRT TV and OSSC->flat panel.

I think it's safe to defer to the 240p game list (https://www.retrorgb.com/dreamcast.html), and not expect that this adapter magically overrides the game's native resolution options. If I'm doing something wrong, I'd love to hear about it.
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by NoAffinity »

I will say that the 31khz RGBs signal output from DreamBaby works nicely with GBS Control's downscaling feature via HD15 input. That was one of the main reasons for getting this adapter, for me.
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:edit: a bit more testing, with Street Fighter Alpha 3. This game will not boot with jumpers configured for either 240p option. The DC startup screen will come up, and once it starts to transition to loading the game, the DC reboots. I find this to be particularly intersting because SFA3 will run in 240p via composite output.

The 480p RGBs option for Street Fighter Alpha 3 works swimmingly, even driving a Sun Microsystems VGA CRT that I previously believed wouldn't support RGBs. It looks simply fantastic! I confirmed this against OSSC also, which sees the signal as RGBs and does not recognize a RGBHV signal from the same output.
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RebeL9
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by RebeL9 »

Hi i have a few questions.

1. The design looks like it would inflict stress on the contact (and maybe?) in the long time cause cracks on the PCB inside the DC?

2. It says that you need to connect it to an upscaler. I’m using a Sony BVM D24 which I’ve hooked up all my consoles using an Extron Crosspoint switch. Couldn’t I use a VGA to BNC cable to connect it to my Crosspoint?

3. how does the image quality differ to other 480p solutions for DC. Such as the cables from RGC, Retro-Access and the Behar Bros Toro?

Thanks!
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by NoAffinity »

I can answer 1 and 2 from my newfound experience with the product.

1) a stand off is provided. You can see it in the pictures in the op. It is a few mm too short, however, and doesn't fully brace the adapter. Not sure if theres a height difference between va0 and va1 at that location. I have a va1.

2) I tested with outputting to a consumer crt TV, PC VGA CRT, OSSC and GBS control. I am also routing the signal through up to 2 extron mvx4 vga matrices. All worked well, with the behaviors I noted above. Basically if your destination device (and routing devices) can accept whatever the DC via DreamBaby is outputting, you should expect that it will work.

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Dochartaigh
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by Dochartaigh »

Does this have the circuit to prevent the top of the image from skewing/flagging on monitors like BVM's?

^^ that is a super common issue I've come across myself on multiple monitors (and multiple DC's), and from TONS of people online too (just the other day had to council 2x people that they need to add an extra device to their setup to fix the flagging - an Extron RGB box with SERR dipswitch turned on... truly a pain for people that just want to play DC!). The RetroAccess Dreamcast cables have this circuit inside their cables fyi...
Last edited by Dochartaigh on Tue Jul 05, 2022 12:41 am, edited 1 time in total.
RebeL9
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by RebeL9 »

Dochartaigh wrote:Does this have the circuit to prevent the top of the image from skewing/flagging on monitors like BVM's?

^^ that is a super common issue I've come across myself on multiple monitors (and multiple DC's), and from TONS of people online too (just the other day had to council 2x people that they need to add an extra device to their setup - an Extron RGB box with SERR dipswitch turned on... truly a pain for people that just want to play DC!). The RetroAccess Dreamcast cables have this circuit inside their cables fyi...
THIS!

Its a major issue when using the cables from RGC and outputting 480p.
Can anyone please report back on this issue from this DreamBaby adapter?
Fed
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Re: DreamBaby - Dreamcast DSUB (15khz | 31Khz) Adapter

Post by Fed »

Dochartaigh wrote:Does this have the circuit to prevent the top of the image from skewing/flagging on monitors like BVM's?

^^ that is a super common issue I've come across myself on multiple monitors (and multiple DC's), and from TONS of people online too (just the other day had to council 2x people that they need to add an extra device to their setup to fix the flagging - an Extron RGB box with SERR dipswitch turned on... truly a pain for people that just want to play DC!). The RetroAccess Dreamcast cables have this circuit inside their cables fyi...
I would love to know also, has anybody found out ? I need this for my 1990r.
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