(SOLVED) HELP! pops, clicks and fainted distorted audio

Hiya from Montreal, first post here. Glad meeting you all
First off, this synth and this board is amazing. Thanks to Olivier and the bunch.

Got the controler board to work, but the lcd trim is acting funny (i’ll keep this for another post), but everything seems fine.
Im a total newb to this DIY stuff so please be patient :wink:

Like some other builders, i have pops and a faint distorted sound in the backgroud.
I went thru the other posts first to try and fix my probs, but i have some questions first.

Would too much solder influence the value of a resistance or cap?
Is it normal that none of the the trim pots affect the sound?
Could a 7.5v 1000ma AC be too low to power the board? Should i go with 9v?
I unwound the reso trim pot quite a bit (way more than 22 turns for sure) without feeling any resistance, is it possible i broke it?

On the bright side, i can hear different content in the different presets, i can hear the lfo in the one called “tremolo” and can make sense of sampled bass in others, so i might be close to my goal. in the meantime, if you have any ideas or suggestions, let me know!

Im not home right now, but will review my soldering and orientations tommorow. Thanks a bunch!

hi!
are you really using an AC supply? it should definitely be DC.

If you are really using AC we can for now stop thinking about anything… while the ATMega might work there will be so much Humm in the Circuit that its nearly MODS. To rule out this issue try running the Shruthi from a 9V Block. Please report the results.

Hugh! Waldorf and Statler have spoken.

It seems to be a great way to have a 50hz-60hz tremolo :slight_smile:

Saves you a LFO…

But you have to move to the power station everytime you want to change the rate :confused:

You may also manipulate the Sun to produce a Geomagnetic Storm that switches out some Nets hence changing the net Frequency… you have to look at the big picture :wink:

Hi, thanks for the help.

the adaptor is a universal AC to DC, so it outputs in DC 3v to 12v

does it need to be dc to dc? total newb here…remember? :wink:

No, AC - DC is what you want, and appear to have. So your problem might still be elsewhere. That said, it could still be worth checking with another power supply. Some of them are terrible quality, which can cause all kinds of problems.
Also, make sure your soundcard/mixer has a low gain on it for testing, as the Shruthi has a hot output on it which can often cause distortion. I added a volume pot to mine, but I believe Olivier changed a resistor in the specs now to tame it (?)

A quick test you can do, which should help narrow down which board is the problem… With the 2 boards hooked up via the test wires, unhook the osc wire, from the analogue board, and probe the jack tip while it is in the output socket. Its a quick and dirty way of bypassing the analogue board. You should hear a nice clean sound? If not, the problem is on the analogue board, or your mixer/soundcard is still distorting from the high output levels.

Are you using a soundcard to amplify the output of the Shruti? If so, try to get through a mixer. I tried to plug my Shruthi into my EMU soundcard and I get a completely distorted sound, if I get through the mixer it’s fine…

Ok, ill try different things tonight…

i went thru monitors direct, guitar amp and thru a sampler input…same thing.

Is it a good idea to go thru the audio in? see if i get normal gain out? does that help?

I will try to hook a 9v battery tonight.

I went thru the french instructions, and wasnt sure about fixing the 10k pots for in and out gain… where am i suppose to hook it up?

the pads for the pots are next to the in and out jacks on the board.

Ill jump the 4pole jumper with wire and go thru all my soldering, test all the parts… i feel i might have missed something so obvious that i cant see it :wink:

Can i assume though that there is nothing wrong with the control board?

ill keep you posted

If the Display displays the buttons button and the leds shine and you see the mutable instruments screen and the buttons chnge the leds - then its fine.

Ok, back home now… I played with the pole jumper, solder a volume knob, hooked it to 9v, reviewed all the part placements…

still the same…

i passed audio thru it…omg that is horrible! i used the audio to modulate the vca… just nasty distortion (perfect for that Broadcast sound ;).

it seem that even no signal from an empty sampler key creates that same distortion as if really low voltage overload the audio in. but damn, i hear the difference going thru the presets… still searchin’…

is it simply that i have a hard time adjusting the trim pots?

i just noticed that the 6th green LED flickers at a high rate when i play a key and comes back at a different intensity, sometimes even off.

Is this normal? Ill review the control board, but i have a hunch that something is shorted or dead, thus draining the voltage… but then again, i dont know much about electronics.

thank you. running into problems building my first kit was expected and even welcomed in a weird way… it forces me learn about electronics. i chose a project that would challenge me a bit (maybe a bit too much ;).

i fell in love with this synth and will make it work eventually.

have you checked that you have the correct voltages at the test points?
maybe it’s just some bad solder joints, loose connections. if there is a short you should read wrong voltages somewhere.