and please, if anyone is reading this and if he will attempt to do comparisons, don't use those silly words (warm, cold, phat, thin, dirty, clean, gritty, oily, pink, smooth, yellow, edgy.. etc. etc..) to describe stuff
the question "how to make my x0x sound like a 303" cannot be answered untill you answer the question "how does a 303 sound like"
IMO you first need to get a 303 as a reference, then compare the differences, understand what these differences are and what causes them
blaming the component brands, shapes, colors, age, and swapping them blindly simply won't get you far
antto wrote:as i already did some tests about Q8 - it makes no difference, not just the hFE value but even the the transistor itself (i found 9 different types of PNP transistors from my old VCR which all worked and sounded the same)
TM4 and TM5 won't make your x0x more 303-ish since these are for tuning your VCO, however, if you slightly detune the "width" (TM5) you can make certain patterns sound a bit more interesting
i think probably in quite a number of acid tracks, the 303s that have been used were "off" more or less
TM3 is a more interesting adjustment, it shifts the frequency range of the filter (so it's equivalent to adding offset to the CUTOFF knob)
many people immediately say that "these two 303s/x0xes don't sound the same AT ALL" if only this setting isn't equal on both units, so it makes a huge difference altho it's a very simple thing
C29, as was discovered not long ago, on all TB-303s this capacitor is soldered "backwards"
it doesn't make a huge difference tho, i suggest you socket it...
now.. for making the x0x sound more like a 303, you need a reference, do you have a TB-303 there?
i have been doing this thing since i got my x0x, and while i don't have a TB-303, i have audio recordings from darffader's 303, which i use as reference
so i did some adjustments according to that
1) my envelope minimum decay time was slightly longer (this is the decay time on accented notes or when DECAY pot is at minimum)
this decay has an impact on the shape of the "wow" on accented notes
i desoldered R138 and used a pot to be able to temporary change it's value while looking on spectrogram to compare the decay time vs the reference, when i nailed it - i measured the resistance of the pot and used 2 resistors in series that gave the same value
2) resonance adjustment - i really recommend this to everyone
in my case i simply wired up a 10K pot in R97 because i need to be able to bring the feedback up to crazy levels for scientifical purposes
but for normal usage i would say you probably only wanna adjust the R97 value between 10K and 8K (below 8K it becomes really insane)
so maybe use a 2K trimpot with 8K resistor or something
i also socketed some other components
C13 - this acts as a LPF and creates the "wow" on accents
Q8 - square waveshaper transistor, tho it makes no difference what i put in there
C11 - square waveshaper this DOES have an effect, it is responsible for the PW characteristics of the square
R36 - square waveshaper this DOES have an effect, it can offset the PW of the square
Q28 - sawtooth buffer, i have placed a J201 tho it didn't change anything
IC11 - ehm, this doesn't have much to do with the sound
Q9, Q10, Q11 - these do some voodoo and are responsible for the VCF cutoff frequency and the parameter "coupling" between the cutoff/envmod/accent, haven't tested them much but basically the act as amplifiers for the signals i think.. Note: i haven't socketed Q11 actually
antto wrote:well if you read what i said, you first have to figure what's "wrong" with the sound of your x0x
if you can't tell by yourself, then just do an A/B test and upload it, we can then all have a listen and figure out where the difference is, and how to "fix" it
antto wrote:TM6 - this adjusts the 5.333 voltage which is used all around the circuit, specifically in the filter and oscillator
if you tweak it and make the 5.333 voltage more - a few things will start to change
does a 303 get 5.33v exactly, with the exception where there is some power supply variation?
Users browsing this forum: No registered users and 5 guests