Tag Archives: SWX09

Want vs. need: Yamaha Seqtrak

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It doesn’t cost anything to window shop!

With the holiday selling season in full swing, I took another look at Yamaha Seqtrak. Ya never know when a bargain might present itself, so it’s good to be ready. 🙂

Seqtrak is Yamaha’s low cost alternative to the all-in-one Teenage Engineering OP-1 — a battery-powered synthesizer, sampler and sequencer. The price is much sweeter, $399 USD (MAP/street), than Teenage Engineering.

I’ve been hesitant to chomp on Seqtrak because I don’t really need a groove box. Yeah, it might provide fun occasionally, but it doesn’t really fulfill a need for what I play live (mainly keyboard emulation of acoustic instruments).

A few postings on Yamaha Musicians Forum motivated me to investigate further, however. Seqtrak implements two forms of synthesis: AWM2 and FM. At first, the AWM2 support sounds like a yawner. Guess what? The AWM2 sound set is pretty much the Motif XF (MOXF) factory sounds! That ain’t chopped liver.

The Seqtrak DX FM implementation is the same as the Reface DX. Even though it’s a four-OP implementation, feedback is supported on any OP, yielding a harmonically richer sound than four-OP of yesteryear. Both DX FM and AWM2 synths can be routed into a robust collection of DSP effects, including rotary speaker, VCM effects and HD reverb.

I wish the Seqtrak DX FM editor supported the Reface DX. It is one nice editor.

Thus, $399 buys a three channel (two synth, one DX FM) battery-powered MIDI module supporting DX FM and Motif XF synthesis. That’s quite a bargain when Reface DX alone costs $400 or so on a typical day.

As an expander, my main quibble is usage model. Seqtrak does not have a display showing the currently selected voice. I can’t tolerate that level of uncertainty during a live performance. The Seqtrak app controls all, but it means schlepping another piece (iPad) to the gig and making everything work live.

Still, it’s enticing. A case of want over need.

Seqtrak inside

What’s inside that tiny box? Thanks to a brave soul on LoopyPro, we get the picture.

Seqtrak consists of three printed circuit boards (PCB): a front panel board which runs most of the length of the chassis, a large digital electronics board mounted in parallel with the front panel board, and a small analog electronics board near the battery and speaker. The analog electronics board has connectors for USB-C, PHONES, AUDIO IN and MIDI.

SeqTrak printed circuit boards

The main event is the digital electronics board, usually called “DM” in Yamaha-speak. In this picture, we are looking at the bottom of the board. The top of the board — sometimes called the “component side” — is obviously out of view. The three large rectangular integrated circuits (IC) are SDRAM (e.g., Winbond W9825G6KH-6 256Mbit Parallel 166 MHz, typically organized as 32MBytes). The specially labelled IC is (likely) a Winbond 256Mbit (32MByte) NOR flash ROM containing the Seqtrak code.

The memory ICs surround the foil pattern for a Yamaha proprietary SWX processor. I’m guessing SWX09 or SWX10. SWX combines an ARM core with AWM2 tone generation and DSP effect processors. Seqtrak implements DX FM because only SWP70 implements FM-X. Low cost devices like Seqtrak usually employ a single, highly integrated SWX and do not include a separate SWP70 tone generator.

There may be additional memory devices on the component side of the DM board. The battery is a 3.6V 2100mAh Li-ion battery.

Copyright © 2024 Paul J. Drongowski

Digital piano: Tear the roof off

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Long-term readers know that my mind will eventually turn to tear-downs and electronics. So it goes with digital pianos.

Thanks to the Piano World Forum, I found two links of interest to deep divers.

Inside Yamaha P-515

First up is a long-ish Yamaha P-515 repair video. I’ve got to say, tearing down a P-515 is not for the faint-hearted. We owe Late Night DIY much gratitude for taking the challenge.

I’d loved to include some screensnaps here, but Late Night’s camera work is a little shaky. (Dude shot the video after a late night gig.) Here is a list of things to watch for:

  • 5:14: Particle board base.
  • 6:57: The AJACK board with external connectors.
  • 7:51: The keybed.
  • 8:17: Rubber contact strips.
  • 9:47: Contact PCB traces.
  • 11:10: Key removal.
  • 24:11: Speaker box.
  • 25:16: AJACK, again. DM board is underneath.
  • 27:07: Top of speaker box.

These camera shots should give you a pretty good tour of the insides without going through the whole disassembly and repair narrative.

Disassembly tips: Take pictures while ripping things apart. Mark holes on printed circuit boards. Do not put screws and other hardware in speaker cones!

A few observations. First, look at the size of the particle board base! The wood base provides strength and rigidity for the NWX keybed. The base must weight at least ten pounds. Think about that when hefting your P-515 around.

The AJACK printed circuit board (PCB) has all of the MIDI and audio connectors. The main PCB — the digital logic (DM) mainboard — is underneath the AJACK. I dearly wish we had pictures (top and bottom) of the DM mainboard.

The rubber contact strips beneath the keys have three nubby buttons for each key. The nubby buttons make contact with the PCB contact traces (those squiggly squares). This is the so-called “triple sensor.” Other than three contacts instead of two, the basic hardware tech ain’t different from digital synths. The hardware “sensor” isn’t that sophisticated as all of the smarts are in the scanning software.

The speaker box is cool. I wouldn’t be surprised to see it inside of P-S500, too. Yamaha reuses components to cut costs and spare parts inventory.

The speaker box and NWX key designs are probably patented. I am surprised that the Piano World folks haven’t exploited the U.S. PTO patent database…

Inside Yamaha CLP-685

Several posts on Piano World Forum cite this look into the Yamaha CLP-685.

More than a look, this is one of the most gutsy tear-downs that I’ve seen. Guy buys an expensive CLP-685 and literally takes it apart out of curiosity. I usually play with my toys before taking them apart and I rarely take apart anything over $100 USD retail. That’s some Chinese chutzpah!

This article has a lot of terrific pictures (some a little blurry, unfortunately). There are good close-up pictures of the tan power supply boards and the DMH main digital electronics board.

Yamaha CLP-685 digital piano main board (DMH)

I wish the DMH board legends were legible and I wish that we had a picture of the other side, too. Plain as day is a Yamaha SWX09 (YH621A0) integrated circuit. The SWX09 integrates the main CPU, tone generation and digital effects onto a single chip. I’ll be thinking about this more in days to come, especially the “empty” board real estate. The SWX09 has nearby companions. The Winbond W9864G6KH-6 4M by 16-bit 166MHz SDRAM is DSP working memory for the SWX09. The two labeled ICs are wave ROM. The rest of the components are mounted on the bottom of the board. We see only the components mounted on the top side of the board.

A Yamaha GrandTouch key

The Piano World Forum folk are positively obsessed with key design and action. Yamaha describe the CLP-685 keybed thus:

GrandTouch keyboard: Wooden keys (white only), synthetic ebony and ivory key tops, escapement

I see a lot of plastic, a metal weight, and a little decorative wood. I’m not hung up on wood vs. plastic as even Einstein would say “Dead mass is dead mass.” If it plays good, why worry? The only concern I have about anything is long-term durability (e.g., those rubber contact strips and dirt).

Hope other musical electronics nerds have found this exposition interesting. 🙂

Copyright © 2023 Paul J. Drongowski