Quick answer: DVI-A is analogue only: it carries the same red, green and blue signals as VGA, with separate sync. HDMI is digital, so no passive adapter can connect them, no matter what the plug looks like. The conversion needs an active box that samples the analogue signal with an ADC, then generates an HDMI timing. Expect 1080p60 at best, no audio, about 20 to 40 ms of added latency, and a picture limited by the analogue source rather than by the converter.
DVI-A exists because early graphics cards kept analogue output for compatibility while adding a digital link, and the DVI-I connector carried both. A DVI-A plug fits a DVI-I socket and uses only the four analogue pins plus ground, which is why a passive HDMI adapter produces nothing at all.
What DVI-A actually carries
Three analogue channels and sync
The analogue section provides red, green and blue at 0.7 V peak into 75 ohm, plus horizontal and vertical sync. Bandwidth depends on the source’s RAMDAC, typically 300 to 400 MHz, which supports 1920×1200 at 60 Hz with a pixel clock around 154 MHz. Above that the edges soften.
No digital pins
A DVI-A cable has no TMDS pairs connected, so an HDMI adapter receives nothing on the pins it uses. Some adapters are sold as DVI to HDMI and work only on DVI-D; the listing rarely distinguishes the two, which is why buyers conclude the adapter is faulty.
The conversion chain
| Stage | Function | Limit it imposes |
|---|
| ADC | Samples each channel at the pixel clock | 8 bit per channel, sampling phase |
| Sync separation | Recovers H and V timing | Unusual timings may not lock |
| Scaling | Converts to a standard HDMI timing | Adds latency and softness |
| HDMI output | Generates TMDS with audio if supplied | HDMI 1.3 or 1.4 stage in most units |
What to expect from the picture
Analogue video through a converter looks like VGA: crisp enough for text at 1080p if the sampling phase is right, but softer than a digital source and prone to slight colour shifts. The converter’s automatic phase adjustment is usually adequate; if text looks smeared, look for a manual phase or clock control in its menu and adjust it against a test pattern.
Audio does not travel on DVI-A. If the device has a 3.5 mm output, run it to the display or the amplifier; some converters include an audio input and embed it into the HDMI stream, which is worth paying for when only one cable can reach the screen.
Alternatives worth considering
If the source has VGA rather than DVI-A, a VGA to HDMI converter is the same product with a different input connector, and the DisplayPort to VGA cables page covers the reverse direction for modern hardware. If the source is a computer with DisplayPort, converting from there avoids the analogue stage entirely, and the VGA to DisplayPort adapter guide covers the opposite case where only VGA is available.
Match the HDMI cable to the output: a converter producing 1080p60 needs only a High Speed cable, and the HDMI cable rating categories guide explains why paying for 48 Gbit/s buys nothing here.
Practical scenarios
- Legacy KVM with DVI-A output: an active converter with 1080p60 output is the only route; a passive adapter will show nothing.
- Industrial panel with VGA output: set the converter to the panel’s native timing rather than 1080p, which avoids double scaling.
- Old presentation PC into a modern TV: accept 1080p60 and route audio from the PC’s jack; the converter cannot create audio from video.
- Point of sale terminal: lock the resolution in the converter’s menu, because the terminal may output a non-standard timing at boot.
FAQ
Will a DVI to HDMI adapter work on a DVI-A port?
No. A passive adapter maps the digital TMDS pairs, and DVI-A has none. Use an active converter with an analogue input, which contains an ADC and a scaler. The plug may fit, but no signal reaches the HDMI side.
Does it support 4K?
No. The analogue source is limited to about 1920×1200 at 60 Hz, and the converter outputs a standard HDMI timing derived from it. Any 4K claim refers to the HDMI output stage, not to the information available from the source.
Why is the image shifted or cropped?
The converter guessed the active area of the analogue signal incorrectly, which is common with non-standard timings. Adjust the horizontal and vertical position in the converter’s menu, or set the source to a standard timing such as 1920×1080 at 60 Hz.
