SEGV echo chan ❤️

[SEGV]

On-board microcontroller streams JAMMA joystick and button inputs in real time over USB for viewing on your PC.

High quality op-amps buffer video with exceptionally low distortion allowing video to be streamed to your PC capture card without affecting the video signal being sent to your arcade machine. Works great with the OSSC and XRGB-mini FRAMEMEISTER.

Hammond broadcast-quality audio transformer provides pro audio grade sound ouput over the nickel-plated steel 3.5mm jack.

$189 + $10 Shipping anywhere in North America via FedEx

FAQ

C-can I see echo chan in a-action?

Sure.

What is video buffering, and why do I need it?

Typical methods of splitting video from a JAMMA PCB usually involve wiring the RGBS lines directly to a DSUB or SCART connector. Since you are essentially telling your PCB to drive two displays instead of one, it will result in a dim image on your display, these PCBs were never designed for such a purpose. Using a video rated op amp allows the signal to be sent to secondary display without affecting the signal that is sent to your primary display (your arcade machine). This is called "buffering" the signal.

My supergun doesn't have any bulky transformer on it, and it still outputs line level audio, whats up with that?

Superguns usually take JAMMA pin 10 (speaker +) and reference it to GND to produce audio out. This has a couple of issues: firstly, there is no guarantee that your PCB audio is GND referenced. There is a common misconception in the arcade community that JAMMA pin L (speaker -) is equivalent to GND. While this may be true for some boards, it is not true in general. JAMMA audio is balanced audio where pin L is the inverted audio signal. Connecting pin L to GND on a board that uses balanced audio will certainly fry the audio amp. Typical 3.5mm jacks are convenient, but are unbalanced. Secondly, by referencing pin 10 to GND you are also introducing noise from ground loops. By using a transformer, you solve both of these issues. Because a transformer is galvanically isolated, you break up these ground loops while also connecting a balanced output to an unbalanced output the right way. As for why we chose this particular transformer, see the next question.

Why the Hammond 560G?

Transformers provide many benefits for us in this case, but choosing the correct transformer is crucial. Most cheaply available PCB mount transformers will provide very poor frequency response, typically 300Hz - 5kHz. Compare this to the average human hearing range (20Hz - 20kHz), and you're cutting out much of the bottom and top end. For reference, here is a 300Hz tone. Since pretty much any arcade game audio will extend well beyond this range, the result with these cheap transformers is accentuated distorted bass frequencies, and overall unbalanced frequency response. A well designed audio transformer will have a core that made of a very specific mix of compounds, but composition is not enough, it must be sufficiently large, but not too large as to still fit on a PCB. The Hammond 560G provides exceptional frequency response (30Hz - 30kHz @ 0dB), and is also electrostatically shielded against external sources of interference while still maintaining a reasonable size. The only downside is that it is an expensive component, retailing for over $50 USD.

SEG-what?

SEGV is a privately funded group of electrical engineers, computer programmers, artists and musicians who love arcade games. We have many exciting projects in the works, so stay tuned ~

 

[Aurich]

I've never had a single problem with any PCBs outputting audio on my HAS supergun, nor have I had any issues with the sound quality. Picking a $50+ transformer feels like crazy overkill, and jacks the price up to the point where my impulse buy instincts got tempered. Just a point of reference.

Looks very nice though.

 

[Derick2k]

What is the intended purpose of this device? audio video splitter? Is it aimed at capture cards. Does it alter any of the signals in any way? Can you please provide more specs/technical details and use scenarios??

 

[opt2not]

What is the intended purpose of this device? audio video splitter? Is it aimed at capture cards. Does it alter any of the signals in any way? Can you please provide more specs/technical details and use scenarios??

I'm trying to wrap my head around this as well.

What is this device for?

 

[SEGV]

What is the intended purpose of this device? audio video splitter? Is it aimed at capture cards. Does it alter any of the signals in any way? Can you please provide more specs/technical details and use scenarios??

It's an audio video splitter aimed at streamers and people who wish to record their gameplay. It also sends your inputs over USB to a PC for viewing inputs alongside gameplay. Check out the link in the first FAQ for a video. Video coming out of DSUB has been attenuated down to safe VGA levels (~0.7V peak-peak). It works when directly connected to a capture card, or with a digitizer like an OSSC.

Sorry if the OP was unclear ><

 

[Derick2k]

What is the intended purpose of this device? audio video splitter? Is it aimed at capture cards. Does it alter any of the signals in any way? Can you please provide more specs/technical details and use scenarios??

It's an audio video splitter aimed at streamers and people who wish to record their gameplay. It also sends your inputs over USB to a PC for viewing inputs alongside gameplay. Check out the link in the first FAQ for a video. Video coming out of DSUB has been attenuated down to safe VGA levels (~0.7V peak-peak). It works when directly connected to a capture card, or with a digitizer like an OSSC.
Sorry if the OP was unclear ><

Ok, now I undestand what it does, very cool for video game streaming or when you want to display content to another display.

Does it display both video and inputs at the same time? How do you generate the video with the inputs displayed?

How does it handle stereo sound input form the pcb? Some pcbs output stereo sound via different connector, meaning not via the jamma edge.

Still deciding if I should get one of these.

 

[SEGV]

What is the intended purpose of this device? audio video splitter? Is it aimed at capture cards. Does it alter any of the signals in any way? Can you please provide more specs/technical details and use scenarios??

It's an audio video splitter aimed at streamers and people who wish to record their gameplay. It also sends your inputs over USB to a PC for viewing inputs alongside gameplay. Check out the link in the first FAQ for a video. Video coming out of DSUB has been attenuated down to safe VGA levels (~0.7V peak-peak). It works when directly connected to a capture card, or with a digitizer like an OSSC.Sorry if the OP was unclear ><

Ok, now I undestand what it does, very cool for video game streaming or when you want to display content to another display.
Does it display both video and inputs at the same time? How do you generate the video with the inputs displayed?

Thanks for the kind words

The input display is handled by our software, entirely plug and play. The software will be available for download from our website (http://segv.moe) when the first units start shipping this week. The protocol for communicating with the board is open source (also to be posted shortly) allowing for 3rd party devs to write their own software with their own skins for the input display. You can even reprogram the microcontroller yourself over USB if you desire.

Displaying both at the same time is easy using recording software such as OBS. That's what we use in our streams.

 

[twistedsymphony]

Pretty cool device, I find the lack of a key slot on the JAMMA edge to be a frustrating omission though.

would also be nice if there were some through holes behind the JAMMA edge for the addition of PCB feet or some other support so that the weight of this device isn't putting a torque on your game PCB.

 

[SEGV]

Pretty cool device, I find the lack of a key slot on the JAMMA edge to be a frustrating omission though.

would also be nice if there were some through holes behind the JAMMA edge for the addition of PCB feet or some other support so that the weight of this device isn't putting a torque on your game PCB.

Appreciate the feedback, we'll include a keyslot in the next batch

We were originally a bit concerned about the weight of the pcb, but during out tests it seemed to support itself quite well. FR4 is surprisingly sturdy:

 

[Sabin]

Hows the integration go? Is it just a separate windows program you’re screen capping into obs/xsplit or is it something else ?

 

[SEGV]

Hows the integration go? Is it just a separate windows program you’re screen capping into obs/xsplit or is it something else ?

Essentially. It's a separate windows program that you can capture using OBS.

 

[rewrite]

Oh man, these are neat. I agree with TS. PCB feet holes, and a keyslot and I'm in.

"Make one of the cabs stream-able" has been on my to-do list for nearing two years now, but lazy. Ha.

 

[AlxUnderBase]

I like your tweet last night and i've read this post too ! Your release is a very nice device ! I'm thinking about one

 

[SEGV]

Oh man, these are neat.

I like your tweet last night and i've read this post too ! Your release is a very nice device ! I'm thinking about one

We really appreciate the positive feedback, guys!

I've received a lot of questions about the choice of the Hammond transformer, so I thought I'd address our design process a bit:

During our design we had a couple of options when handling line out:

1. Use speaker (+) referenced to GND.
As mentioned in the FAQ, this is not the way to handle balanced audio.

2. Use a cheaper transformer.
The next runner up we had was a telecom grade transformer which cost around 10USD. While testing, the sound was just okay.

We're not going to lie and say that you need an audio grade transformer to have a good experience, but hey, you don't need a BMW to get from point A to point B. Using a cheaper transformer would have ended up saving the consumer around 40 USD, and relative to the price of many of the games we were using for testing (some of which go for over $1000 USD unfortunately...), we didn't want to cut any corners. This is our first product, and we wanted it to make it the best we could.

Competing products that use the Tamura series transformers are telecom grade transformers. These are not intended for audio applications and have a frequency response in the range of 300Hz - 4kHz at 0dB, compared to 30Hz - 30kHz from the Hammond. Here is a clip from the datasheet:

 

[sammargh]

So why all this talk about balanced audio and then slapping a 3.5mm connector for output? Seems rather silly to throw such a big transformer on to balance the audio signal and then terminate it with an unbalanced connector unless you're only doing 1 channel TRS output which won't work well for a majority of people this is targeting.

 

[SEGV]

So why all this talk about balanced audio and then slapping a 3.5mm connector for output? Seems rather silly to throw such a big transformer on to balance the audio signal and then terminate it with an unbalanced connector unless you're only doing 1 channel TRS output which won't work well for a majority of people this is targeting.

The majority of people this is targeting are going to use 3.5mm for recording audio. Yes, it is a large transformer, but as mentioned in the FAQ the frequency response of an audio transformer is directly proportional to the size of the core. Yes, TRS would not work well for the majority of people this is targeting, that is why we did not use it.

 

[Frank_fjs]

I know what a cheap transformer does to audio so am glad you're using an expensive one.

Could you explain something to me, re the Tamura, how is that being used as a speaker to line level converter when it has a turn ratio of 1:1?

 

[TechnicalMonkey]

I would have liked balance outputs, I know you would too, @Sabin @beast1x5 @cruzlink2 @Hatsune Mike @mugen_ketsueki and others. I am sure that the other adapter coupled with an inexpensive ground loop isolator would do the job well for most casual streamers.

If you are intending this to be for the arcade connoisseur/pro streamer, why not just go all out? I know I would like to see like:

1. controls for RGB gain and offset with multiple turns (I like 8, but 4 or 5 might be a better middle ground. Perhaps this can be a separate breakout box for the hdb15 port. Personally I can imagine something even crazier.)
2. Why only one two video outputs are considered? Why not 3 outputs like in head to head candy cabinets?
3. Pin 7 keyed out for those that may need that and don't want to ruin their new $200 adapter.
4. Will you be selling separate adapters for different pinout variations (JAMMA, Neo Geo, etc.)

I'm sure I'm forgetting something here, but I'll leave in at this point for now.

 

[Hatsune Mike]

I would have liked balance outputs, I know you would too, @Sabin @beast1x5 @cruzlink2 @Hatsune Mike @mugen_ketsueki and others. I am sure that the other adapter coupled with an inexpensive ground loop isolator would do the job well for most casual streamers.

If you are intending this to be for the arcade connoisseur/pro streamer, why not just go all out? I know I would like to see like:

1. controls for RGB gain and offset with multiple turns (I like 8, but 4 or 5 might be a better middle ground. Perhaps this can be a separate breakout box for the hdb15 port. Personally I can imagine something even crazier.)
2. Why only one two video outputs are considered? Why not 3 outputs like in head to head candy cabinets?
3. Pin 7 keyed out for those that may need that and don't want to ruin their new $200 adapter.
4. Will you be selling separate adapters for different pinout variations (JAMMA, Neo Geo, etc.)

I'm sure I'm forgetting something here, but I'll leave in at this point for now.

As for balanced outputs, that would not make a lot of sense. The entire point of the transformer for either of our boards is to properly isolate from the JAMMA board's balanced output to a usable line signal with reference to ground.

As for RGB gain, and offset, I think a unified gain is useful (to control total output level, so Vpp is within the expected range) but I think individual channel bias and gain controls should be disallowed on such a board. The overall reason is that I'm frustrated seeing cabinets and capture setups with out of wack black levels and sickly white points. I do not want to introduce yet another point of frustration for this - and for two reasons, I want to emphasize that these controls should not be necessary on a card like this.

First, if you need to adjust the bias for your capture setup, something is wrong with your board or your setup. The constant DC offset exists on nearly every JAMMA board that represents a black level is supposed to be clamped in the horizontal front porch. Your monitor and capture setup should be doing this.

Second, the same point remains for gain for each channel. Unless you have a problematic board, the white point should not need to be adjusted. It should be calibrated on the capture setup, as well as on the monitor, not through an interstitial board.

 

[SEGV]

I know what a cheap transformer does to audio so am glad you're using an expensive one.

Could you explain something to me, re the Tamura, how is that being used as a speaker to line level converter when it has a turn ratio of 1:1?

I can only speak about my design, but for what it's worth even with the Hammond there's a turn ratio of 1:1. We don't use a step-down transformer to attenuate the audio, we use a voltage divider.

I would have liked balance outputs, I know you would too, @Sabin @beast1x5 @cruzlink2 @Hatsune Mike @mugen_ketsueki and others. I am sure that the other adapter coupled with an inexpensive ground loop isolator would do the job well for most casual streamers.

If you are intending this to be for the arcade connoisseur/pro streamer, why not just go all out? I know I would like to see like:

1. controls for RGB gain and offset with multiple turns (I like 8, but 4 or 5 might be a better middle ground. Perhaps this can be a separate breakout box for the hdb15 port. Personally I can imagine something even crazier.)
2. Why only one two video outputs are considered? Why not 3 outputs like in head to head candy cabinets?
3. Pin 7 keyed out for those that may need that and don't want to ruin their new $200 adapter.
4. Will you be selling separate adapters for different pinout variations (JAMMA, Neo Geo, etc.)

I'm sure I'm forgetting something here, but I'll leave in at this point for now.

Good questions. You'll probably see a theme, our design philosophy was not just aiming for high quality but also convenience for the end user.

1. RGB gain requires some explanation. We certainly spent a lot of time considering our options.

Many solutions will use ganged potentiometers (3 pots one for each color channel, but 1 dial controlling all 3 pots). The problem is that the tolerances on the pots are pretty lax. Cumulatively their difference can yield variances between color channels as high as 20%. You basically roll the dice, some units will be more or less fine and others will have really messed up color balance. There's no way to tell without a lot of testing of each individual part, so it's very labor intensive, you end up throwing parts away, and the final product still has slightly misaligned color balance.

The next option would be to use 3 separate pots. I don't know about you, but we hate fiddling with tiny pots trying to get the right balance of red green and blue. It's a pain.

The vast majority of arcade boards will be outputting roughly the same voltage on RGB, so we stepped it down using precision resistors (tolerance of 0.1%) to ensure the color balance comes out PERFECT. We tested on ~50 JAMMA games covering all popular hardware platforms and a good spread of years. Everything from the oldest of JAMMA games to the jankiest of Korean games to the late Cave SH3 games... Without exception no adjustment to gain was required. Considering that all decent capture equipment also lets you adjust gain, we went with this approach to preserve color balance (and leave further micro adjustments to the capture hardware itself).

2. Do you think others would be interested in having multiple splits? We may have to consider that. But it sounds like a different product.

For this product, we were going for the capture / streaming market and didn't want to inflate the cost more than we already did with features that would go unused by most of those users. The premium features we have (Hammond audio transformer, input streaming) should be value adds for everyone, whereas additional video splitting would probably go unused most of the time.

3. Yeah, we regret this unintentional design choice. For decades we have automatically distinguished parts side from solder side on our PCBs so we didn't even think of the fact that it's not effortless for others.

4. Sure we'd build a Neo Geo variant if there was demand, it would not even take much modification. As-is, the device works perfectly with a 1 slot MVS and should be compatible with multi slot MVS while using JAMMA adapters. For those people crazy enough to human centipede their setup.