Soma - LYRA-8 DIY Kit

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Re: Soma - LYRA-8 DIY Kit

Post by autodafe » Fri Feb 19, 2021 3:53 am

After checking everything possible, I think I solved my issue with PITCH opening all voices 5- to 8

I din't put plastic washers under the small "pad" screws because "hey, the panel is made of PCB material, it's not conductive".
Well, I don't know what happened, maybe the DIN Screws scratched the silskcreen paint just enough to touch the ground plane below, maybe there was some paint issue on the panel, but putting plastic washers under the pads seems to solve the bleeding issue.
Now I only have a very small bleed when turning the PITCH knob, but that happens on voices 1-4 as well...

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Re: Soma - LYRA-8 DIY Kit

Post by HenryBurlingame » Mon Feb 22, 2021 1:10 am

Hey all, what are the most recent lyra-8 board revisions for the three boards (main board, control board, and the small breakout board)?
FS (US): Nothing: viewtopic.php?f=74&t=238432

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Re: Soma - LYRA-8 DIY Kit

Post by mutronic » Mon Feb 22, 2021 9:08 pm

So after tearing the damn thing apart again I found the culprit to all my voice/pad problems - solder joints on the connectors. All pads are ago.

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Re: Soma - LYRA-8 DIY Kit

Post by mutronic » Mon Feb 22, 2021 9:12 pm

HenryBurlingame wrote:
Mon Feb 22, 2021 1:10 am
Hey all, what are the most recent lyra-8 board revisions for the three boards (main board, control board, and the small breakout board)?
The board I received that I believe was the last ones he sent out is a v2.6.

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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Tue Feb 23, 2021 10:04 am

Yes, current factory units are 3.3/3.4, but they use different board to board connections and pots are not on the backplane.
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Re: Soma - LYRA-8 DIY Kit

Post by HenryBurlingame » Tue Feb 23, 2021 1:06 pm

Flounderguts wrote:
Tue Feb 23, 2021 10:04 am
Yes, current factory units are 3.3/3.4, but they use different board to board connections and pots are not on the backplane.
Oh, interesting, so the current factory boards are different than the current DIY ones?

Do you know how long they have been using the rev. 3.3/3.4 boards?
FS (US): Nothing: viewtopic.php?f=74&t=238432

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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Tue Feb 23, 2021 8:04 pm

HenryBurlingame wrote:
Tue Feb 23, 2021 1:06 pm

Oh, interesting, so the current factory boards are different than the current DIY ones?

Do you know how long they have been using the rev. 3.3/3.4 boards?
No idea, but probably since Sound Machines has been doing the manufacturing. There are no major differences in the design, other than some alternative parts and footprints. The distortion cap is SMT, and the NXP 4093's have both DIP and SOIC footprints. The IO board has footprints for the on/off switch and a headphone jack. Also, there is a ferrite choke on the IO board that is on the V2.2 boards, but not on the DIY boards. The 47 nF caps on the opamps are film, instead of ceramic. The major difference is the board to board connectors, which are arduino-style long pin connectors which are lined up...which is the best part, because the #1 issue with DIY builds has to do with those connections. There are some minor placement tweaks for decoupling caps on the 4093 BEAT ic...but I couldn't find any actual differences in the circuit layout.

The control board is much tidier, and there are some parts that are a bit different from the Official DIY BOM, but to my knowledge they have all been documented in this thread.

A solid DIY build acts exactly like the factory instrument, although there is an intermittent appearance (in some builds) of excessive LFO click bleed. No one has been able to isolate the problem, but it is probably related to poor grounding and poor connections between control and main boards...which is why it's an "intermittent" problem that only affects some builds.

Hope that helps.
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Re: Soma - LYRA-8 DIY Kit

Post by HenryBurlingame » Tue Feb 23, 2021 8:32 pm

Thanks so much flounderguts, very helpful!
FS (US): Nothing: viewtopic.php?f=74&t=238432

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Re: Soma - LYRA-8 DIY Kit

Post by buttdispenser » Sat Mar 20, 2021 3:21 am

Quick practical question on the soldering: How should I go about soldering the IC sockets and connector pins onto the top side? For most components I have no problem with this but I find it impossible to heat the solder without melting the plastic of the IC sockets. I just have a rather cheap soldering iron for which unfortunately there are no small/flat tips available.

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Re: Soma - LYRA-8 DIY Kit

Post by t3hh » Sat Mar 20, 2021 10:41 am

what I usually do is to solder the pins on opposite corners and then solder all the pins one-by-one using a lot of flux

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Re: Soma - LYRA-8 DIY Kit

Post by buttdispenser » Sat Mar 20, 2021 11:11 am

With "a lot of flux" being essential here :hihi: I guess this way the solder finds its way to the pad itself and I don't have to get too close to the plastic that way

Edit: I have tried it, but still I can't really get to the pads without melting the plastic, especially at the IC sockets
Last edited by buttdispenser on Sat Mar 20, 2021 12:08 pm, edited 1 time in total.

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Re: Soma - LYRA-8 DIY Kit

Post by buttdispenser » Sat Mar 20, 2021 11:15 am

Flounderguts wrote:
Tue Feb 23, 2021 8:04 pm
[ The 47 nF caps on the opamps are film, instead of ceramic.
Do you know why they sometimes use film caps instead of ceramic ones?
Last edited by buttdispenser on Sat Mar 20, 2021 5:45 pm, edited 1 time in total.

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Re: Soma - LYRA-8 DIY Kit

Post by t3hh » Sat Mar 20, 2021 2:13 pm

buttdispenser wrote:
Sat Mar 20, 2021 11:11 am
Edit: I have tried it, but still I can't really get to the pads without melting the plastic, especially at the IC sockets
there is a ghetto way to do it, that is to solder the sockets while having chips in them. However, as there is chance to damage the chips, it should be used only with dummy chips that are not essential for your build.

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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Sun Mar 21, 2021 10:50 am

I eliminated the sockets on mine.

What kind of solder are you using? Cheap solder alloys tend to melt unevenly and make it harder. Also, if your iron is too cool, it's easy to sink too much heat into the sockets...counterintuitive, I know! If you're melting the sockets, make sure you let everything cool before reworking it...or you may end up lifting an overheated trace.
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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Sun Mar 21, 2021 10:53 am

buttdispenser wrote:
Sat Mar 20, 2021 11:15 am
Flounderguts wrote:
Tue Feb 23, 2021 8:04 pm
[ The 47 nF caps on the opamps are film, instead of ceramic.
Do you know why they sometimes use film caps instead of ceramic ones?
Availability? Using up inventory? Or maybe those opamps are affecting the audio path on the "sharp" knob? I know my DIY sharp knob has a different timbre from the factory...
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Re: Soma - LYRA-8 DIY Kit

Post by theburningtrestle » Sat Mar 27, 2021 5:39 am

buttdispenser wrote:
Sat Mar 20, 2021 11:15 am
Flounderguts wrote:
Tue Feb 23, 2021 8:04 pm
[ The 47 nF caps on the opamps are film, instead of ceramic.
Do you know why they sometimes use film caps instead of ceramic ones?
different types of caps have different properties - film caps IIRC have a linear decay wheres ceramic have a logarithmic decay. this means they're not always interchangeable and if a Polycap is specified you should use Poly but generally in my experience you can replace ceramic with poly .

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Re: Soma - LYRA-8 DIY Kit

Post by theburningtrestle » Sat Mar 27, 2021 6:42 pm

Anyone out there with FM issues when FM isn’t toggled. I can definitely hear FM between Voices 1 to 4. Also there’s a brief amplitude drop when lowering the Pitch knob in Group 1.

Any advice greatly appreciated!

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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Sat Mar 27, 2021 8:55 pm

theburningtrestle wrote:
Sat Mar 27, 2021 6:42 pm
Anyone out there with FM issues when FM isn’t toggled. I can definitely hear FM between Voices 1 to 4. Also there’s a brief amplitude drop when lowering the Pitch knob in Group 1.

Any advice greatly appreciated!
What do you mean by "issues?" FM bleed? Wiggle the hold knob a bit. Or maybe you have ongoing FM feedback in the delay loop? Also, the pitch knob and the tuning knobs are in the same circuit, and amplitude drops are to be expected when you change the voltage...especially dropping pitch.

Also make sure you don't have it set up so that 12 is affecting 34...or vice versa. That will also bring up some (lovely) artifacts.
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Re: Soma - LYRA-8 DIY Kit

Post by theburningtrestle » Sat Apr 03, 2021 5:39 pm

Flounderguts wrote:
Sat Mar 27, 2021 8:55 pm
theburningtrestle wrote:
Sat Mar 27, 2021 6:42 pm
Anyone out there with FM issues when FM isn’t toggled. I can definitely hear FM between Voices 1 to 4. Also there’s a brief amplitude drop when lowering the Pitch knob in Group 1.

Any advice greatly appreciated!
What do you mean by "issues?" FM bleed? Wiggle the hold knob a bit. Or maybe you have ongoing FM feedback in the delay loop? Also, the pitch knob and the tuning knobs are in the same circuit, and amplitude drops are to be expected when you change the voltage...especially dropping pitch.

Also make sure you don't have it set up so that 12 is affecting 34...or vice versa. That will also bring up some (lovely) artifacts.
Hi there,

I should clarify:
when `I'm tuning any of the 1-4 voices whilst playin simultaneously that I'm getting FM effects ie square wave beats instead of the usual sine wave beats. All the mod switches are set to "off".

Curiously I notice that only the '56" switch has continuity with ground. I thought this was odd. Hard to tell from the schematic but I would have guessed that all the the mod switches would have been set up the same way - I wondered if this was causing the FM issue.

The amplitude when i alter Voices 1-4 Pitch bounces down and then back up. This is not similar to what happens when I Pitch Voices 5-8.

I know these things are cross modulating monsters but it seems I have something awry somewhere but I'm damned if I can find it.

I added a ground strap from the TOTAL FB and VIBRATO as the wires were already in place by the guy I bought this off but I'm finding it odd that the MOD don't all show continuity to ground the same way.

Other than that the thing is fine but the FM/tuning issues is bugging me - it's making it difficult to microtune the Voices a cent or two out for thickening effects.


Any thoughts?

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Re: Soma - LYRA-8 DIY Kit

Post by theburningtrestle » Sat Apr 03, 2021 5:40 pm

odd that the MOD *switches* don't all show continuity to ground the same way.

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Re: Soma - LYRA-8 DIY Kit

Post by Flounderguts » Sun Apr 04, 2021 2:30 pm

theburningtrestle wrote:
Sat Apr 03, 2021 5:39 pm
Hi there,

I should clarify:
when `I'm tuning any of the 1-4 voices whilst playin simultaneously that I'm getting FM effects ie square wave beats instead of the usual sine wave beats. All the mod switches are set to "off".
Yes, that occurs at certain times. I'm not sure what you mean by "mod switch," unless you are referring to the cross-modulation routes ie 12>34 or the 12/off/LFO switches. All the MOD adjustments are pots.
Curiously I notice that only the '56" switch has continuity with ground. I thought this was odd. Hard to tell from the schematic but I would have guessed that all the the mod switches would have been set up the same way - I wondered if this was causing the FM issue.
I would love to know about "the schematic" you are referring to!
The amplitude when i alter Voices 1-4 Pitch bounces down and then back up. This is not similar to what happens when I Pitch Voices 5-8.
Yeah, Lyra amplitudes are a bit weird, and they are affected not only by the pitch and tuning knobs...but by the actual pitch as well. As your pitch goes up, so does the amplitude, which is a behavior well documented in the main Lyra-8 thread.
I know these things are cross modulating monsters but it seems I have something awry somewhere but I'm damned if I can find it.
Hehe...the people who can live with and work around the weirdnesses are the people who keep their Lyras :hihi:

It's sort of like the Viola de Gamba of the electronic desktop synth world!
I added a ground strap from the TOTAL FB and VIBRATO as the wires were already in place by the guy I bought this off but I'm finding it odd that the MOD don't all show continuity to ground the same way.

Other than that the thing is fine but the FM/tuning issues is bugging me - it's making it difficult to microtune the Voices a cent or two out for thickening effects.
The ground on the FB and VIB should just be from the switch body to the chassis ground. All it does is prevent hum when you touch those switches...a sleeve on the switch bat would work as well. So I'm having trouble following what this continuity to ground thing you're referring to is. For the most part, GROUND and the 0V is interconnected, and you can think of it as a floating ground...but the chassis ground is isolated from the rest via a 5.1 ohm resistor.

From a grounding standpoint, it's a complex instrument. I have been running mine off of a lab power supply in my rack, and I have been observing some odd behavior, especially when plugging or unplugging jacks. It seems like when the tip hits the ring contact, the power consumption jumps about 3 or 4 fold, which stops once the plug is all the way in or out (switched jack closing or opening, I presume)

Slight power fluctuations create interesting global pitch effects. Also, the instruments seem to have a bit of a "burn-in" time, where the exact operations changes a bit after you have had some combinations dialed in.

As for microtuning, it IS difficult to do with *adjacent* oscillators. Try spacing them out...3 and 7, 4 and 6, etc. I actually find myself using 1 and 2 as a single droney thing, 4 as a thickener, 3 solely to modulate 12 and 4. Then I run 5 and 6 as the meat, and 78 as a descant or funky stuff. As mine is an expanded version, I can dial voices in with wildly different pitch ranges, which helps keep stuff manageable, from a modulation standpoint. I also have a factory version, and it's a bit tougher to use that way because I can't dial the pitches for adjacent pairs as far apart, which is why I developed the idea of spacing pitch pairs apart.
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Re: Soma - LYRA-8 DIY Kit

Post by theburningtrestle » Mon Apr 05, 2021 1:57 pm

Thanks so much for your detailed response !

Sorry when I said "schematic" I meant the PCB layout PDF which is the build doc from SOMA.

I can live with "FM" cross-mod weirdness if I know it's er.. shall we say "not unnormal" :hihi:

The 56/off/LFO switch was the cuplrit - I took it all apart and tested it again and only intermittently got continuity from the switch body to ground. I took the nut gave it a blow and re-assembled it and the problem has gone (for now) I wonder if a crumb of solder or strand of wire was trapped there?

The weird thing about this is that now Voices 1 and 2 are more stable whereas before they tended to warble a bit!

I liked your point about tuning strategies BTW - I'll give that a go. Usually by the time I get up to VOICEs 7 and 8 I'm already making er... music and tune them on an ad hoc basis.

I had considered swap the pots out for multi turn but I've got two hopes of finding multi-turn C-log pots (and of those is Bob Hope!)
I've kludged in a Bournes 2k trimmer in series with which gives me a fine tune range of 4 or 5 notes so I'm going to put some pots in on the front of my case for fine tuning. I fully expect these to be useful if I'm using the thing like an Organ rather than the unruly beast that it is!

I'm fascinated by the "burn in" time you mentioned - I'm going to look out for that.

Lyra's a keeper for sure - I have a Synthi A - again another device which has quirks and foibles and is rarely ever the same twice! I'm looking forward to interlocking them at some point!

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