CX Cards
Conexant CX2388x-xx lis an 2002 era PCI-based chip line-up, today found with a PCIe bridge chip (Asmedia or ITE) in the 1x PCIe desktop card form factor.
With CXADC it becomes an powerful 28-40msps 8-bit Analogue to Digital Converter!
CX White (CX23883-39) S-Video/RCA input.
This page has overview information, for more in-depth information on the driver and cards click the links below.
- Linux Driver - Software Installation & Usage
- Wiki - Detailed Hardware Information
- Windows Driver - Windows Driver of CXADC
Note
The CXADC driver now supports up to 256 cards, so setups can be scaled as much as you need, and external timing sources allow it to do clock locked sampling of different signals in the same deck, so zero hardware audio/video drift issues.
Note
It appears, vendors that had CX23881 in there listing are now shipping the newer and better current White CX25800 type cards and have not updated there listing titles at all so assume you will get either or.
Current CX White CX25800 Card Order Links Link 1 / Link 2 / Link 3 (16~30 USD)
Why PCIe 1x Cards and not any old PCI card?
Standardised hardware makes it easier to support the software/hardware interoperability for RF Capture. A standardised PCB layout, with predictable and dependably similar performance, allows for easy modification, standardised guides, and sample comparison.
If you have a multichannel format yes upto 3 cards, if you have a signal channel format possibly no.
- For Video8/Hi8/LaserDisc PAL & NTSC (Betamax NTSC is also combined signal)
1 physically single path for Video RF & HiFi RF capture.
You will only need one card for Video/HiFi FM RF capture, but will benefit from a 40MHz crystal mod if you don't go got the clockgen mod.
- For SMPTE-A/B/C to 2" Quaduplex
You only need one card for Video RF, but you will need a clockgen mod setup which has a standard audio ADC for capturing the baseband (linear), audio or timecode tracks which are line-level.
2 physically separate paths for Video RF & HiFi RF audio capture, ideal to setup with a clockgen mod setup.
- VHS/SVHS & (Betamax PAL) - Video & HiFi.
- Betacam - These have dual video channel track capture & Linear Audio.
- Betacam SP/MI/MII/W-VHS - These have dual video channel track capture ++ HiFi Audio & also Linear Audio.
On the white card without physical modification, it's recommended to use the S-Video port (Luma or Y signal pin and ground) for FM RF signal capture if you wish to not solder your own cables or modify the card in any way, but C31 removal mod is encouraged.
The CX chips have an internal digital gain amplifier, which if used, can generate unwanted self noise.
To mitigate this, you may use an external amplifier to increase the amplitude before it gets to the card, this can also compensate for longer cabling if unavoidable.
An amplifier is an affordable way to negate the issue and is a soft mod (via SMA cables soldered internally or soldered directly to bulkheads mounted on your VCR) to the capture chain in most setups for tape formats, and can even be powered by a VCRs internal 5~18V DC power connections.
| The ADA4857 Dual Channel Amplifier |
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The ADA4857 board provides a way to better match the impedance of the test point and put less load on it, instead of the 100~200Ohm input on some off-shelf boards (which were used in some early capture setups with varied results) you can set a much more ideal range of 10~40 kOhm for the input impedance with cheap 0805 SMD resistor parts, is just a day of adjust up and adjust down test captures until the picture's SNR stops changing.
The CX Card by default is designed around capturing composite video, so is intended for use with signals with stronger 1~2vpp range with a 75 Ohm load which is not optimal and the extra load on the vcr amplifier caused by this can also potentially lead to some distortion on the output, so an amplifier limiting the signal on input then sending out a 75 Ohm 1.5vpp one is very comfortable for the CX Cards or even newer cards like the MISRC.
Tip
Do not use PCBway for less than 5 unit orders, you will pay 3 times more than KoFi for a single built amplifier.
Order Links: ADA4857 KoFi & ADA4857 PCBway
Tip
If being used externally with a Sony 8mm Camcorder for example, you may want to use a small 12v 9ah standard lead-acid battery these are fairly common & cheap but also produce pure DC power and will last over a day of capturing before requiring a recharge or swap out.
Features:
- Improved operating stability
Adding a 40x40mm heatsink is recommended, you may mount a fan or place a external fan to provide airflow, please check spacing in your PC case.
Faster sampling data output = more heat = shorter hardware life and possible loss of capture data due to overheating.
File the heat sink's mounts down, so as not to touch board components. Secure the heat sink & fan unit onto the chip. Do NOT forget to use thermal paste and/or thermal pad on the heat sink, putting tape around the metal is also a good idea but be sure not to obstruct the chip.
Tip
Silicone sealant is recommended over hot glue for affixing heatsyncs to the cards, due to the risk of melting, and ease of removal without damaging parts unlike epoxy.
Requirements:
- Soldering Iron with Bevel/Chisel Tip, Flux, 60/40 Solder
- 40x40mm heat sync & fan
- Thermal Pad / Thermal Paste
- Silicone Glue
Warning
Move C31 to pad C16 if using a cards 3rd connector pads, some cards may now have 3rd hole openings on the brackets and are suitable for this.
Features:
- Improved signal-to-noise ratio (SNR)
Note
The label on the white card picture above these cards have a bridging capacitor on pad C31 this bridges the two input pads for RCA/BNC connectors, and causes worse captures due to adding signal reflections.
It's best to always remove either with a iron tap both sides then lightly pressure from one side to knock it off the 2 pads its soldered to, or remove with a gentle twist with tweezers/pliers.
Tip
Use some low-melt solder such as ChipQuick or 70c casting solder, can be used to flow onto the RCA connector pads & crystal pads to remove it in one peice easily with pliers/twezers.
Warning
Move C31 to pad C16 if using a cards 3rd connector pads, some cards may now have 3rd hole openings on the brackets and are suitable for this.
Features:
- Improved physical connection (Secure locking BNC)
With de-soldering and a pair of flush cutters, you can replace the RCA connector and or add another input with BNC which is a lot more reliable and flexible than RCA.
Can I just use the un-populated pad? Yes! Just get a drill bit and make a new hole on the bracket.
AliExpress 1 / Amazon US / Amazon UK / Walmart Canada / OEM DOSIN-801-0073
Tip
Use some low-melt solder such as ChipQuick or 70c casting solder, can be used to flow onto the RCA connector pads & crystal pads to remove it in one peice easily with pliers/twezers.
Features:
-
Improved capture workflow (capture server)
-
Software Defined Crystal Rate 20/28/40/50MHz modes (40MHz is optimal)
-
Hardware Synchronised Multi-Card Capture (shared clock source)
-
Audio ADC for Synchronized Baseband (Linear or Decoded HiFi from device) Audio Capture
The most advanced mod available today, using an external crystal timing source we can have drift free capture with 2-4 CX Cards and audio feeds.
This allows duel channel video formats such as Betacam to be captured, or Video FM + HiFi FM + Linear for many other formats like VHS or Betamax.
External crystal timing via 2 additional PCB boards, a Jig with an SMA and mainboard has allowed for under 50USD multi card sync, using 2 or more CX Cards alongside an extra input for synchronised Linear/Reference audio capture also has a extra input for head switching timing signals.
- Raspberry Pi Pico as the interface and control board.
- Adafruit Si5351A for generating the shared clock source with 5 potential inputs.
- PCM1802 PCB ADC for L/R input baseband Linear or HiFi audio capture.
Audio inputs and head switch input is on a dedicated bracket you can 3D print or drill a metal one this example is from the kofi store.
Clock Speed rate (20/28.6/40/50 MHz modes) is controlled by alsamixer like an normal audio device would be, allowing to set each card to a range of fixed rates. (40MHz being standard, 28.6MHz being stock)
For Laserdisc capture you may want to use the LPF mod (low pass filter) and more information can be read in greater details on Tony's wiki that covers mods and amplifier modding to optimise for LaserDisc only use.
Caution
Now considered legacy due to the clockgen mod providing a more flexible workflow, for all but LaserDisc, Video8/Hi8 tapes which are all "HiFi" only being true single RF channel capture formats.
ABRACON ABLS2-40.000MHz-D4YF-T Digikey / Farnell (can be sourced from most vendors)
Features:
- Increased Sampling Speed
- Increased Signal to Noise
Note
CX Cards can go up-to 57MHz on some cards, with 48MHz being possible on most white card variants with 40MHz being the standard choice as it's the most optimal SNR (Signal to Noise) wise for the ADC.
This simple "cheep and dirty" modification is just replacing the stock crystal with a soldering iron, an instant drop-in upgrade to 40msps 8-bit capture or 20msps 16-bit capture, though the CX2388x-xx cards are made for upto 54MHz crystal support in testing 40MHz is generally achievable by any card and matches the DomesDayDuplicator, this also improves the SNR of the CX Chips.
This mod makes the cards ideal for Video8/Hi8/SVHS/ED-Beta/SMPTE 1" & LaserDisc capture on a budget.
Caution
Adding a 40mm heat sync & an direct fan or pointed at fan for extra airlfow is also recommended more data = more heat = shorter hardware life and possible loss of capture data.
Note
Not all crystals are perfect and some can be defective and dramatically out of spec, so It's recommended to order a few.
- FAQ - Frequently Asked Questions
- Diagram Breakdowns
- Visual-Comparisons
- VCR Reports / RF Tap Examples
- Download & Contribute Data
- Speed Testing
- Capture Setup Guide
- MISRC
- CX Cards & CXADC
- CX Cards - Clockgen Mod
- DdD - Domesday Duplicator
- RTL-SDR
- Hardware Installation Guide
- Finding RF Tap Locations
- Amplifier Setup Guide
- The Tap List Example VCR's
- Visual VBI Data Guide
- Closed Captioning
- Teletext
- WSS Wide - Screen Signalling
- VITC Timecode
- VITS Signals
- XDS Data (PBS)
- Video ID IEC 61880
- Auto Audio Align
- Vapoursynth TBC Median Stacking Guide
- Ruxpin-Decode & TV Teddy Tapes
- Tony's GNU Radio For Dummies Guide
- Tony's GNU Radio Scripts
- DomesDay Duplicator Utilities
- ld-decode Utilities