Recommendations/sources for video cables and patch cables

Oh! I know what should work better (again, assuming the MP can take a non-blank composite signal as sync):

Pretty much what you described, but move the VU001 to be after the composite-to-component adapter, and run the Y output from the c-to-c adapter through the VU001 then to the MP and the VU003’s Y input. The Y channel carries the sync, so that way, you’ll end up syncing the MP with the same signal you’re feeding into the VU003.

(Sorry if that hid the last few posts for everyone – I didn’t realize what would happen. I flagged the discussion about getting video into the MP as off-topic in hopes they’d be moved to a separate thread, since it’s not really about video cables or patch cables.)

1 Like

Good move, worthy of its own discussion and keeps this thread on topic

1 Like

Does anyone have information on which brands of 3.5 mm patch cables have the best fidelity for video? The least high frequency signal loss? Especially with HDTV formats, it makes a huge difference. I’m seeing noticeably softer video using TipTop Audio StackCables, compared to LZX RGB mini-snakes.

Shielding is nice, but I’m less concerned about noise than about signal loss. In a perfect world, someone would manufacture 3.5 mm cables optimized for video. Robust, high fidelity, well shielded.

1 Like

I really like the Control Cables

It’s been mentioned that extra shielding causes capacitance, which degrades high frequency video signals.

3 Likes

At first, I didn’t really noticed a difference between cables when using a linear power supply/SD system based around Cadets. Later, I switched to a lighter case powered by switching supplies, and the cheap no-name cables I was using were picking a lot of noise from the PSU, so I went for Polar Noise Shielded cables, which helped greatly with the noise.

Then I started building a system around HD modules, and that’s where cables shielding/length started making a difference. Both parameters effect the capacitance of the cable, which basically creates a filter between the two modules connected, hence why it helps with high frequency noise coming from a switching PSU.

Here are some tests I already posted on the Discord a while ago, with a black and white checkerboard in 720p60 as a source, with direct connection from VU003B to VU007B.

Same cable length, different shielding:

Same shielding, different cable length, Polar Noise Shielded iirc:

I’ve also tested with alligator clips (basically cables with no shielding), it does improve the bandwidth but picks up a lot of noise (from Capsule PSU iirc). Second capture is with RG179 cable and Rean jacks, RG179 is specified at 64pF/m, jack sockets also adds a bit of capacitance, so didn’t really noticed a difference with RGB minisnakes. Last one is Tendrils, which are up to par with Polar Noise Shielded from what I’ve tried:

Haven’t tried other cable types, though seems like RGB Minisnake performs the best, then keeping connection between modules short does also help, but it gets tricky with dense patches and/or passive splitting. Also, all those captures are 720p60 which is the format that requires the most bandwidth, so going for a lower resolution/framerate could also help.
Seems like it will always be a tradeoff between bandwidth vs noise immunity, though I only tested with VU003B/VU007B with a Capsule power supply, I guess Gen3 modules might be less prone to noise since they all have their own integrated power supply.

10 Likes

They should be – part of it is that the scale of any noise is much lower with +/-5V power rails than +/-12V rails. With Capsule power, we measured 1-2mV under full load. With the Gen3 integrated power, it is less than 400uV. Anything under 3-4mV is effectively ignored, once the video is digitized at 24-bit RGB.

6 Likes

Thanks Bastien, that is super helpful.

So far it looks like the best way to go is the RGB mini-snakes. When I have time, I will do some tests with the other cables I have here, TipTop, Hosa, and Ad Infinitum. Will report back with findings.

3 Likes

Sounds like Gen 4 modules are going to need twisted pair differential signals/cables!

If you think video modules are expensive now, just wait for how much they are with double or more the amount of op amps required for differential signals. :slight_smile:

1 Like

I think the real answer, for that concern, is just that modules with 75R terminated video IO (on RCA or BNC connectors) is not excluded by the 1V patchable spec at all, they are part of it. So there’s nothing preventing someone from designing a “mastering series” module with BNC I/O for the sensitive video path, for example, and still including 1V CV inputs for modulation. We just haven’t made any modules like that yet.

Differential IOs can still be a thing, too – just split across two jacks (like the IQ +/- outs/ins on Swatch.)

8 Likes

Please do not make me go back to the Busted kNuckle Connectors. Frankly the Eurorack standard is too small and flimsy for that. Even just using the RCA jacks on decoders / encoders, I live in fear that by simply making the connection I am going to crack the module front panel, or worse. There is a reason the Sandin IP is built of all stainless steel front panels.

Also not really into the idea of differential signals carried by two 3.5mm cables, except in special cases. Eurorack is very compact. That’s great. Not everyone has a huge interior space for a monster system. Doubling the number of connections would increase patch complexity and HP width.

All I really want is a 3.5mm cable that can have lengths up to 1m without high frequency signal loss and without RF interference. In the absence of this, there’s actually a limit to how large a system can physically grow without introducing high frequency signal loss. At a certain point one would need to devote HP space to some kind of custom buss modules to send signals over longer distances via BNCs or whatever. Or just have tons of buffered mults everywhere.

By the way, I took the advice of @creatorlars and rebuilt my entire system to minimize cable lengths. Everything that needs video sync in one rack. All the low frequency signal sources in a separate rack. That’s not a solution to the problem of 3.5mm cables being crappy, but it’s a workaround for my mid-sized system, which will ultimately be 672 HP non-inclusive of Chromagnon.

I think there might be some sync issues in the first two.

For the record, I was just kidding about differential signals/cables. :slight_smile:

4 Likes

I don’t think it’s totally crazy. Obviously it’s made it possible to send analog video down incredibly long cable runs, e.g. security cameras. Just difficult and expensive to implement in a modular synth.

I understand! I’m quite happy with the performance of the Gen3 modules and 3.5mm patching in the noise/power/transmission department. It’s a practical and balanced approach to offering analog video art tools at the price point we’re targeting. I’m just saying that if we ever needed to accelerate the performance in that area, for example, for a very high precision use case (like a broadcast mastering tool), that nothing prevents us in the standard from having RCA/BNC IO directly on module.

4 Likes

Reviving this after I discovered noise when I plugged “black market” brand 3.5mm patch cables into the inputs on DSG3 without the other end patched elsewhere yet. It’s making a lot of uneven noise, and none of my other brands of 3.5mm patch cable brands show this behavior. Once the cable is patched to something else, it’s hard to determine if it’s more noisy than other brands, but this unpatched behavior is suspicious. Makes me wonder if these cables are related to the issues I’ve been having with noise in Mapper patches, as even separating Mapper onto it’s own rig with it’s own power I still got noisy patches. :man_facepalming:

Anyone got recommends for 3.5mm slim patch cable brands? Looking into Control as mentioned above, but taking another survey with this forum bump

That’s weird!

Did you try a few different blackmarket cables? Try both plugs?
All tests use cables of similar length? Just trying to rule out anything that may be effecting the measurement.

Makes me think the ground ring on the plug has a connectivity issue or is worn out, but if you’re seeing the same thing on a few different cables then that’s weird.

1 Like

It was all 20 of my black market cables, 4 different lengths :man_shrugging: They all made different but similar uneven noise patterns, I’ll take a capture soon. I think they are just not shielded well, the pattern changes and intensifies if I touch the cable anywhere on the length. Other brands none of this silliness.

Any chance of seeing the 15cm / 6" RGB mini-snakes again? Or some substitute? I missed the boat on this. Never knew they existed until I saw them in Nick’s demos.

2 Likes