Posts by awai@fosstodon.org
(DIR) Post #Arzo7TiMpMbiGYjnfM by awai@fosstodon.org
2025-03-12T16:37:50Z
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Amp switcher: relays array design π§΅Background story: https://fosstodon.org/@awai/114093865582292065Project overview: https://fosstodon.org/@awai/114110547162586997As I mentioned previously, I intend to design a single board for both the input and ouput switching sections.I had initially planned to have only the jacks (and associated relays/circuitry) going to/from the amp on the board; then I wanted to add the speaker out jack, and maybe also a buffer, and make it optional, and... Well, you get the idea π1/#Guitar #Amplifier #DIY
(DIR) Post #Arzo7URk6eu4XHy2OO by awai@fosstodon.org
2025-03-12T16:39:25Z
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In the end, the relays array PCB will include the following features:* choice of on-board jack connector or screw terminal block* ability to handle both guitar- and speaker-level signals* optional built-in buffer (for use in the "guitar input" section only)The first listed feature is the easiest one to implement: it only requires to ensure the board has footprints (and holes!) for both types of connectors, and decide which one should be populated at build time π2/
(DIR) Post #Arzo7VkZG9YWZxmaNE by awai@fosstodon.org
2025-03-12T16:40:22Z
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Handling both types of signal also comes with a few constraints: first, we need relatively wide PCB tracks to deal with the speaker current (nearly 5A for a 100W tube amp cranked up into an 8Ξ© speaker π±).I went for 2mm as it's likely enough for 20-30W amplifiers; however, more powerful amps will require a bigger copper section.As the available space is limited, my recommendation would be to order the board with 2oz copper weight (instead of the standard 1oz), that should do the trick! π3/
(DIR) Post #Arzo7WJJAzLSJi2KWW by awai@fosstodon.org
2025-03-12T16:42:31Z
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We also need to mute the input of unused amps and ensure a dummy load is connected to their output. This is especially important for tube amps, which NEED a speaker(ish) load.Unused amps' jacks should then be shorted when used as the input section, and 2W-rated resistors (only dissipating low-power noise) be placed across them in the other case.All this requires is adding a solder jumper: one can then either populate the resistor (output), or solder the jumper to close it (input).4/
(DIR) Post #Arzo7XV2kqKI0OXDSC by awai@fosstodon.org
2025-03-12T16:43:46Z
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Finally, the input buffer: I went for a tried-and-true design using a single OPA134 op-amp, which I have always been happy with.Using similar "tricks" (additional footprints + solder jumper) this section can easily be bypassed and left unpopulated if it's un{need,want}ed and/or the board is used for the output section.REMINDER: this buffer can only be used for the "guitar input" section, as it would be destroyed by a speaker-level signal, possibly damaging the amplifier in the process!5/
(DIR) Post #Arzo7YPPNHPepCuEJE by awai@fosstodon.org
2025-03-12T16:45:04Z
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The next feature I wanted is the ability to "resize" the board post-manufacturing: I actually plan to build 2 devices, one for each of my amplifier stacks (a 6-way switcher for the "modern" stack, and a 2-way device for the "vintage" one).As I need 2 PCBs per device (4 in total), and minimal order is 5 pcs, I could build both devices just by ordering a single board design made for 6 amplifiers, and "downsize" 2 boards so they only include the circuitry needed for 2 amps.6/
(DIR) Post #Arzo7YtBaZESJYq0iu by awai@fosstodon.org
2025-03-12T16:47:18Z
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Therefore I designed the PCB as a single block of 2 jacks/relays, repeated multiple times to reach the desired (even) quantity, and simply added the buffer/connectors block to the result.I also added oblong holes separating each block, only leaving the needed space for the PCB tracks to run to the next block: this way, I can easily cut a larger-than-needed board to the desired length without any additional tooling π7/
(DIR) Post #Arzo7ZONiaBZsJQvLc by awai@fosstodon.org
2025-03-12T16:47:55Z
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As initially announced, this project is of course 100% #OpenHardware :openhardware: and is licensed under the terms of the CERN-OHL-S v2 or later.The #KiCAD source files for the "relays array" board are already available from https://github.com/a-wai/amp-switcher , the rest will follow as soon as I implement it π8/8#OSHW
(DIR) Post #Awt3mQ4yDeJX63g4jg by awai@fosstodon.org
2025-08-06T08:14:37Z
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@tobykurien Please don't link to a prebuilt .deb without providing links to the full source code and/or patch
(DIR) Post #AwtC0PDl0Rnc7dy3kW by awai@fosstodon.org
2025-08-06T09:47:48Z
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@tobykurien Thanks! Your post is now GPL-compliant π
(DIR) Post #AxIaqFzLpeeKOmU7zE by awai@fosstodon.org
2025-08-18T15:05:30Z
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I got my new @starlabssystems StarLite 5 this morning, replacing a Surface Go 2 which is starting to show its age...Of course I've immediately installed @debian #Trixie and #Phosh, and after #rsync'ing my /home from the SG2 it's good to go, with everything working out-of-the-box! (including the cameras, yes)This definitely demonstrates how far ARM-based devices are from wider adoption, and how a Linux-first x86 #Tablet can still be very relevant to end users!#LinuxMobile #Debian
(DIR) Post #AxIaqLUjMPilTYCl5k by awai@fosstodon.org
2025-08-18T15:14:19Z
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@starlabssystems @debian Oh, and it came with the latest Coreboot (v25.06), built only 3 weeks ago! I'm amazed at how up-to-date the firmware is, right from the factory π―
(DIR) Post #AyGGqeohvkpTgneNou by awai@fosstodon.org
2025-09-16T10:11:54Z
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@micr0 "Pragmatic" solutions only work up to a certain point.Halium is the most pragmatic solution for running Linux on (many) mobile devices. But you have to accept running proprietary software and outdated, unsupported kernels. It's good for people that want something that just/mostly works, though.Mainline-based #LinuxOnMobile is an attempt at getting rid of those proprietary bits, and it matters to lots of us. So no, we won't go the pragmatic route, even if it holds us back for a while π
(DIR) Post #AzGasNH4MvLiVMNFlQ by awai@fosstodon.org
2025-10-16T07:47:41Z
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@bart @tasket @fun The drivers vs. firmware distinction isn't clear from their announcement, as they mention "firmware and binary blobs" and "proprietary binary modules". Some drivers (and corresponding userspace HAL and libraries) being binary blobs, those could technically be reverse-engineered and ported to mainline. If that happened, that could be of interest to the #LinuxMobile community.
(DIR) Post #AzTBbj7JvtfTWjG47k by awai@fosstodon.org
2025-10-22T13:58:58Z
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TIL about Easy Effects which allows to easily apply various filters (EQ, compressor...) to the audio output (or even input) using #PipeWire on #Linux: https://github.com/wwmm/easyeffects πI use a Focusrite 18i20 audio interface, with 2 sets of speakers: either the main monitors on my desk, or a Bose Soundlink Mini sitting on top of my guitar amplifier.Switching between the monitors and the Bose is as easy as pressing the "ALT" switch on the 18i20, but then I had a tiny problem...1/#LinuxAudio
(DIR) Post #AzTBbjyUkCCcBe8X0S by awai@fosstodon.org
2025-10-22T14:03:30Z
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The Bose is used mainly when playing the guitar, either for playing along a tune, or for listening to the click track without having to put headphones on.Of course, this requires that the volume is set quite high in order to hear it without being completely drowned in the guitar sound.The problem is, as this speaker has a rather prominent low-end, the sound at a high volume is excessively boomy, and I don't want my whole building to collapse, right?2/
(DIR) Post #AzTBbl3Uj5nPXRU2RE by awai@fosstodon.org
2025-10-22T14:13:03Z
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At first I considered buying a rack-mount graphic EQ (e.g. Behringer Ultragraph) so I could EQ the signal sent to the Bose without affecting the main monitors. However, do I really need a full-featured EQ just for cutting some low-end? No, not really...My next idea was building myself a DIY stereo low-cut filter with a bunch of capacitors and a rotary switch, but that would've required buying a few parts I was missing, as well as an additional cable or 2... And I'm in "lazy mode" this week3/
(DIR) Post #AzTBbldeYeifLaOunY by awai@fosstodon.org
2025-10-22T14:15:25Z
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With Easy Effects I could quickly dial in an EQ curve that would tame the low-end just the right amount so the Bose would still sound lively, without getting any of the problematic rumble...Now this also affected my main monitors, so I'd need to open Easy Effects any time I'd switch speakers and manually enable/disable the EQ. But then, I'm a nerd, that's also a problem I can solve πThe "ALT" button is reported as an ALSA control named "Speaker Switching", which will come in handy!4/
(DIR) Post #AzdGktaUuarR5Zqlw8 by awai@fosstodon.org
2025-10-27T10:56:26Z
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This! Buy from local (independent) stores instead of online giants; attend live shows, and buy merch directly from the bands; eat locally-grown (organic) food; use privacy-focused, community-built online services; buy used gear & equipment instead of brand new ones; and of course, do it all based on what you can afford and as a best-effort thing, without being hard on yourself if/when it just isn't possible.For sure, it won't change the world, but it will feel good πhttps://terminal.ahumanfuture.co/posts/2025-10-17/the-world-is-something-that-we-make/
(DIR) Post #B0dRUdcDkK0qyCEdhg by awai@fosstodon.org
2025-11-26T08:50:02Z
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@kop316 @linmob @Liberux The PhD isn't required, it's "highly valued" (although I suspect they actually meant "Master's degree" or something similar)