Commander X16

Hey all... Board# PR01146 has arrived in Cherry Hill, NJ.

Got it all set up. Installed the 2nd CIA, buffered, extra RAM. Put in the Midi card+wavetable, and the network card.

Started running through stuff on the SD card (after backing it all up).

So, first issue - tried playing music through Melodius on the card...

* Anything playing on the VERA PSG channel sounds pretty good. Nice and clear... (For example, Goonies.zsm or any of the Metal Gear folder)
* Playing YM2151 channel stuff sounds very distorted. I used Marble Madness Level 2 as a test because I remember what that sounds like. It's the music, but it's hard to describe the distortion. It's almost like it's being played on a blown speaker or like it's overdriven and clipping at the top end.
* Playing any MIDI file likewise sounds horrible distorted. NOTHING like the clean sound we heard in the 2023 and 2024 presentations.

First I thought maybe the MIDI and Network card might be interfering with each other. Pulled the network card - no change. Pulled the Little Dreamer off the MIDI card. No difference. Pulled the Midi card altogether. Playing midi files sounds EXACTLY the same!!! (almost like it wasn't using the midi card at all!)

I'm using Melodius dated 20240622 ...

Any ideas??? I'm totally at a loss right now. Do I have a bad Yamaha chip? How come midi wasn't being played via the MIDI card? Do I need a newer version of Melodius? Is there something wrong with my X16?? Should I not be using powered speakers? (they're little Logitech desktop small ones. Am I wrong that I should be using powered vs unpowered?)

Vera: V47.0.2
X16 ROM Ver R48

It sounds to me like the MIDI files are playing through the FM chip, and either the FM chip, the DAC, or the pre-amp for the DAC is not working.

The one thing that's easy to test is the power supply. The FM audio circuit relies on negative voltage from the power supply, so if you have a multimeter, you can test the -12V line. (You can also check the label on your power supply and see if pin 14 is even wired. Some modern PSUs leave that disconnected.)

Can you check your power supply and confirm that it puts out -12V on pin 14?

Ok, MooingLemur helped me figure out how to set things up in Melodius (and pointed me to the latest version), so I have the MIDI card working now... THAT is nice and clean...

Anything playing VERA PSG is also nice and clean sounding.

But OMG the YAMAHA is just distortion city.

Is it possible I have a bad Yamaha chip?

TomXP411 wrote: ↑Tue Apr 01, 2025 11:10 pm It sounds to me like the MIDI files are playing through the FM chip, and either the FM chip, the DAC, or the pre-amp for the DAC is not working.

The one thing that's easy to test is the power supply. The FM audio circuit relies on negative voltage from the power supply, so if you have a multimeter, you can test the -12V line. (You can also check the label on your power supply and see if pin 14 is even wired. Some modern PSUs leave that disconnected.)

Can you check your power supply and confirm that it puts out -12V on pin 14?

Using the Pico Power supply that TexElec was selling with them.. So it SHOULD be good... ???

Mkopack73 wrote: ↑Tue Apr 01, 2025 11:14 pm

TomXP411 wrote: ↑Tue Apr 01, 2025 11:10 pm It sounds to me like the MIDI files are playing through the FM chip, and either the FM chip, the DAC, or the pre-amp for the DAC is not working.

The one thing that's easy to test is the power supply. The FM audio circuit relies on negative voltage from the power supply, so if you have a multimeter, you can test the -12V line. (You can also check the label on your power supply and see if pin 14 is even wired. Some modern PSUs leave that disconnected.)

Can you check your power supply and confirm that it puts out -12V on pin 14?

Using the Pico Power supply that TexElec was selling with them.. So it SHOULD be good... ???

Yeah, that power supply should work just fine. That's what I've been using.

I'll ping @Texelec on Discord and see if he has more suggestions.

Just a follow up…

Got in touch with TexElec and send them a sample of what I was hearing. They sent me out a replacement DAC and Yamaha sound chip. Turns out it was the DAC that was bad. They said I’m like the 3rd they’ve had this issue with. To be expected when we are dealing with 30-40 yr old chips.

So I’m all good now. Sounds great! Between the Yamaha, Vera, and Midi board this thing has seriously impressive sound capabilities!