Start up chirp and possible warble

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lis0r
 
Posts: 2
Joined: Wed Jul 09, 2014 8:11 am

Start up chirp and possible warble

Post by lis0r »

Hi all,

I gathered my own boards and parts to build a x0xb0x. I'm powering it from the second output from a giant linear PSU I built for my MB-6582, so there should be no supply problems. I've added mods for bass boost, a flexi-clip circuit for distortion diodes, and a custom board between the microcontroller and cutoff CV in mod to provide MIDI CC cutoff. The bass boost has been set to "default", and the remaining mods disconnected while diagnosing, though.

The first time round, I had the dreaded filter wobble, and the AN6562 got pretty toasty. I isolated this to the 4066 being bad, swapped it out, and things seem *better*, but I'm not sure they're right.

On power up, there's a little chirp sound, and I've not managed to work out if this is expected?

The AN6562 no longer gets hot, but under sustained use becomes what I'd consider lukewarm - it's discernable from the baseline temperature. I can't tell if it sounds quite right when all the filter related knobs are cranked high, or if it's still a little too liquidy. It might just be me being paranoid!

Does anyone have any suggestions of how I can verify it's correct?

Thanks!

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antto
 
Posts: 1636
Joined: Thu Apr 15, 2010 3:21 pm

Re: Start up chirp and possible warble

Post by antto »

well, the x0xb0x power supply section is designed to take 9V AC, just saying so you know
if you got all the voltages from the IO board in sane ranges (12V, 5.33V, 6V, and 5V) without anything melting or excessively hot - i guess it's "okay" then

as for the startup sound - could you record it?
it's normal to get some sort of pop sound on power on, since all the caps charge up and so on.. but after a second or two - everything should settle
in some rare cases the synth might produce a note (the voltages happen to trigger the envelope) but that would decay down and dissapear in about 5 seconds, after which everything is normal

lis0r
 
Posts: 2
Joined: Wed Jul 09, 2014 8:11 am

Re: Start up chirp and possible warble

Post by lis0r »

Hi antto, all,

Sorry for the thread resurrection - after my previous post, there were some fairly major changes in my personal life, and I've not really had time to play with the x0xb0x until now.

The MB-6582 also takes 9VAC, so it should be OK. Powering it up again, it no longer seems to make the chirp, just a soft pop - I don't know if that's good or bad! If it comes back, I'll try and record it.

I have made a recording of the waveforms: http://www.bismuth83.co.uk/~lisa/x0x.m4a http://www.bismuth83.co.uk/~lisa/x0x2.m4a

The sequence is as follows: (tune centre, env mod max, decay min, accent max, volume 1PM)

1) Saw, cutoff min, resonance min, C
2) Saw, cutoff min, resonance min, C accent
3) Saw, cutoff max, resonance min, C
4) Saw, cutoff max, resonance min, C accent
5) Saw, cutoff max, resonance max, C
6) Saw, cutoff max, resonance max, C accent
7) Sqr, cutoff min, resonance min, C
8) Sqr, cutoff min, resonance min, C accent
9) Sqr, cutoff max, resonance min, C
10) Sqr, cutoff max, resonance min, C accent
11) Sqr, cutoff max, resonance max, C
12) Sqr, cutoff max, resonance max, C accent

2nd file
1) Saw, cutoff min, resonance max, C
1) Saw, cutoff min, resonance max, C accent
1) Sqr, cutoff min, resonance max, C
1) Sqr, cutoff min, resonance max, C accent

Do these sound right, or are they too bubbly with the resonance turned up? I've noticed in my DAW that the saw wave seems to be asymmetrical, i.e. it goes higher above 0 than it goes below it - I checked the signal generators with an oscilloscope when I built it, and they tested out OK. Does this seem right?

Thanks! :)

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