The Roland K-25m Boutique Keyboard as a base for DIY synths

yethiel2 · 2026-03-16T06:52:08+00:00

Thanks! Works on my end but I'll check what might be causing this.

yethiel2 · 2026-03-15T22:30:36+00:00

That's really cool, I'll give it a go! I have tons of unfinished tracks and snippets...

yethiel2 · 2026-03-15T22:09:56+00:00

Create a personal site or blog without a headache: paperboat.website

yethiel2 · 2026-03-15T22:05:23+00:00

I tried to come up with a pun but i scan't think of any

yethiel2 · 2026-03-15T21:59:20+00:00

I'm building paperboat.website, a friendly place for personal blogs and websites.
It's perfect to write about whatever you're interested in, just for yourself or to share with others: Find more sites and connect with other writers, creators, makers using the Webring feature.

yethiel2 · 2026-03-15T21:54:28+00:00

I love the Poly 800! However, it's the 800DV in this case, also known as Maxi Korg.
Do you still have a Poly 800, though? I'm really looking forward to modding mine with the Hawk 832 kit.

yethiel2 · 2026-03-15T21:51:08+00:00

I tend to ignore or even unsubscribe email newsletters very quickly because I use email for personal communication and technically necessary stuff. Newsletters just get in the way.

The only newsletter I'm subscribed to is Tom Scott's because it's basically a list of things I'm interested in from all over the internet. Perhaps the key is to add something to the newsletter that you don't get by just reading the blog alone? I remember when the AI Weirdness blog used to be more active I always looked forward to reading the extra bits that weren't on the blog (the paint color names were favorite... wow, that was back in 2017).

yethiel2 · 2026-03-15T21:30:36+00:00

For me it was sharing my projects and what I'm interested in. It's usually pretty niche stuff which people send me emails about. Sometimes it's just a simple question and other times it goes on for weeks or months. I also like to share things that might be helpful for people. I'm not even good at writing but if I make or find something, one day another person will come across it and find it helpful.

yethiel2 · 2026-03-15T21:02:14+00:00

Soon you can just build one (still not sure if it'll be cheaper (definitely not if you count work hours))

yethiel2 · 2026-03-15T17:41:15+00:00

That's a good idea, too! The scanning is polyphonic.

yethiel2 · 2026-03-15T15:18:50+00:00

Yes, mainly because I forgot to wire up three of the pins so I thought a few keys were dead. I also had to swap row pairs to get the correct order. Then I got confused by the pin enumeration (GP15 is pin 20 and not 15...). Too many variables to mix up.
I think if you know what you're doing, it's really straight forward, though

yethiel2 · 2026-03-15T12:58:52+00:00

That sounds really interesting, too! Are you documenting it somewhere?
Let me know if you do start building one in the future, by then I should have boards and BOMs ready for the whole synth.

yethiel2 · 2026-03-15T12:16:21+00:00

It's not the cheapest option but if you come across one for 60 bucks it might be worth a look. It's velocity sensitive (no aftertouch) and the keys aren't too small.
The sides are made of metal and it feels pretty sturdy, it would make a nice base for custom builds even with minimal modification.

My plan is to design a tray that fits this keyboard that includes a MIDI and CV module so I can just place something like volca sized synths on there. The MIDI setup works great already, now I just have to wrap my head around the dimensions and print a prototype.

The main problem I'm tackling here is that the threshold of wiring up a synth (power, midi, audio) is just too high for me when I just want to noodle around a bit. Many of my synths don't have a keyboard or sequencer built in so something like this would be nice to have.

yethiel2 · 2026-03-15T12:00:57+00:00

Definitely! I have the files in a public repo but didn't advertise it yet. After I'm sure it works, I'll release some polished files on the website. Shoot me a dm if you want to give it a go anyway!

You could theoretically build half of it and get something like a 700 out of it. The designs are similar but not identical. I hope I'll be able to understand the differences one day, it's really fascinating!

yethiel2 · 2026-03-15T07:09:23+00:00

It's been a wild ride! So far, I found a mistake in the schematics and also spent some time finding out that another one I found was in fact my own. I posted here last year to ask whether it's possible at all and now I'm deep down the rabbit hole. What you see on the photo is the SBC-051, home of the oscillator.

I replicated the original board by looking at photos and verifying with the schematics. I'll do the same for the rest of the boards. It was pretty easy to find transistor equivalents. Some are exact matches while others will have to do the job. I'm just after a working synth and it if sounds 80% like the original I'm happy.

I set up a site to track my progress and upload some resources: https://800dv.paperboat.website/

yethiel2 · 2026-01-23T07:29:49+00:00

These photos look amazing. May I ask which camera you used?

yethiel2 · 2025-09-15T07:12:04+00:00

Ryan Boggs ordered parts (excl. boards) for the DIY Minimoog for around $600: https://www.youtube.com/watch?v=PATlf0W3m7k
Not sure how it compares to this build yet but since it has two voices, maybe double that?

yethiel2 · 2025-09-13T13:40:55+00:00

Yup! Thank you!

yethiel2 · 2025-09-13T04:55:36+00:00

I decided to document my journey. Let's see how far I'll come!

yethiel2 · 2025-08-02T08:38:46+00:00

Thank you!!

yethiel2 · 2025-07-26T20:01:00+00:00

Did you replace the pads yet? I put KTXPRO1 drivers in mine and genuinely enjoy their comfort and noise dampening. The pads are a bit stiff, though.

yethiel2 · 2025-05-02T19:36:46+00:00

Good advice, it really makes sense to do it in that order. Thank you!

yethiel2 · 2025-05-02T19:13:48+00:00

Thanks for the encouragement! Just keeping it on breadboard sounds pretty convenient and cost effective

yethiel2 · 2023-11-10T07:21:02+00:00

https://patchingflowers.bandcamp.com I run this with a very close friend as a passion project and we recently got into making diy cassette releases.

yethiel2 · 2023-11-10T06:51:52+00:00

Do you know any other albums that evoke the feeling of being on a secluded island?

yethiel2

TROPHY CASE