e-licktronic Forum

Hello,

I finished a yocto yesterday and everything is fine, just a problem in the snare circuit.. the tone pot works in reverse, which means the pitch gets higher turning it clockwise.. I already desoldered it to check it's value and it's right with B104.. I also checked the parts for right orientation/value..

attached is a measurement done at the middle pin of vr8 with 3 settings of the pot: fully open - mid position - fully closed



any thoughts? I found a topic from 2014 where someone had a problem with snappy but he also wrote that his tone pot behaves like mine, but there wasn't a solution..

Cheers

it's not "pitch", so there's no "tuning"
the snare is a burst of noise (the snappy) mixed with the "body"
the "body" itself is made up from two resonators at different frequencies, and the TONE parameter is a "balance" between them

just to be clear, when the TONE parameter is set low - you should get only the lower-freq resonator
in the middle they should both be audible
when the TONE is set high - you should hear only the high-freq resonator

if they're swapped ... then they must be swapped
probably wrong resistors/capacitors in the the two, or in one of them, or some other issue around that area

the passive R/C components in the resonators are very sensitive usually, so it's easy to affect them (and their frequency and/or resonance will change), so watch out for some neighbour resistor touching or some imperfections around the solder joints.. see if the tuning changes when you brush the board with a brush

thanks for your explanation, but as far as I know pitch is related to frequency and the tone control changes the frequency as you wrote? so if turning the tone pot changes the frequency imho this implies that you change the pitch of the (body) snare.. nevertheless, the frequency goes higher turning the pot clockwise, so it's somehow reversed

I am going to check the components again but I already tripple checked the parts of the bridged T-networks around IC14 and couldn't find a problem.. are there different revisions of the snare drum? in the tr808 service manual c58 and c59 are both 27nF whereas the yocto uses 56nF and 27nF and the values of the resistors are the same.

i wasn't clear enough
there are two resonators at fixed frequencies, the TONE pot mixes/balances the audio outputs from them
there's no actual frequency/pitch tuning going on

but i also failed to read your first post carefully:

... the pitch gets higher turning it clockwise..

that's the correct behavior, no idea why you thought that's "reverse"

antto wrote:i wasn't clear enough
there are two resonators at fixed frequencies, the TONE pot mixes/balances the audio outputs from them
there's no actual frequency/pitch tuning going on

but i also failed to read your first post carefully:

... the pitch gets higher turning it clockwise..

that's the correct behavior, no idea why you thought that's "reverse"

I don't know why I wrote it goes higher, it went lower in my case turning the pot clockwise since I had a 562 instead 563 in one of the resonators
I understand that the tone pot acts as balance pot between the two bridged T-networks which resonate at different frequencies, but nevertheless you change the pitch turning the tone pot, I don't know why you can't agree here... How'd you explain a musician what the tone pot does? I'd say you change the pitch of the body of the snare, he'd listen and he'd agree

another question about snappy, the snare sounds a bit thin, all other instruments sound fine.. I have measured 130mV rms at R127, I calibrated the clap.. toms sound nice, maracas sound nice.. I already tried the changes suggested in the service manual..

this was how it sounded before I swapped the cap, so ignore the wrong pitch focus is on snappy:

https://www.sendspace.com/file/91jn7l

decoder303 wrote:I understand that the tone pot acts as balance pot between the two bridged T-networks which resonate at different frequencies, but nevertheless you change the pitch turning the tone pot, I don't know why you can't agree here...

my understanding of the language might be a bit broken, but as far as i know, pitch is frequency
there's no change in frequency happening
but don't trust me, trust Roland.. the parameter is labeled TONE
there is a place where actual frequency is being changed, and there the parameter is labeled TUNING

How'd you explain a musician what the tone pot does? I'd say you change the pitch of the body of the snare, he'd listen and he'd agree

see how Roland labeled the parameters on the front panel, i believe these devices were targeted at musicians
this is closer to mixing between two oscillators, or between two audio channels on a mixer than it is to changing pitch

here's your recording (from the beginning where you turn the TONE parameter):

in the middle you can see the two resonators together.. the lower one is at about 320Hz the other one is at about 550Hz in your case

another question about snappy, the snare sounds a bit thin, all other instruments sound fine.. I have measured 130mV rms at R127, I calibrated the clap.. toms sound nice, maracas sound nice.. I already tried the changes suggested in the service manual..

this was how it sounded before I swapped the cap, so ignore the wrong pitch focus is on snappy:

well, i compared it quickly to my snare from one of my first tracks.. when we ignore the "body" frequencies the snappy seems roughly comparable
i can't record a reference sample anymore because i modded my snare to increase the snappy decay time
perhaps compare yours to 808 samples from a sample library or so (if nothing else, you could get the audio from my first youtube video of the yocto, it was panned left, with no processing/fx, and no mods yet)

yeah, pitch is frequency and if my understanding is right, one resonator oscillates at lower frequency than the other and the tone pot controls the amplitudes of the signals from resonator "low frequency" and resonator "high frequency" which pass to the output.
looking at your sonogram, there obviously is a change of pitch imo, as you wrote, the frequencies are around 320 and 550 Hz. So, in this case, turning the pot fully to the right just 320 hz are at the output, and turning the pot fully left, you'll only have the 550 hz signal.. imo that's pitching around
it certainly isn't the same as a tune pot but it definitely is related to pitch, imho.

I heard some yoctos with longer decay on youtube, the demo from elicktronic is pretty much how my snare sounds, but there are other yocto demos where it's sounding nicer imo. specially also related to the decay, so maybe these yoctos also have a decay mod installed.. I am just wondering since I also noticed differences on some 808 demos, some where the snare is pretty short too and others where the snare has a longer decay.. I prefer the ones with longer decay big time, so I am gonna try to increase its decay too, maybe I like it better.
I was just a bit surprised, since I am used to the 606 snare since ages and it sounds really fat compared to the yocto snare (and maybe also compared to an tr808 snare)..