More 303-like + calibration...

[rarara]

Hi,

I am trying to get my x0xb0x to sound more squelchy/acidic, and before I swap-out any components etc I thought I'd best try and get the closest sound out of the current components.

Searching some threads there seems to be a few recommendations for increasing the value of TM6. If I bump that up I need to retune the VCO correct? Without a 'scope and just by using my ears, how can I get this done?

Do I need to adjust TM3 too? Are there any voltages I need to check?

Upon originally building my machine many years ago I can't recall doing much calibration except getting the odd voltage to 5.333. Anyone have any suggestions?

[aminoacid]

tm-3 is the trim point for tuning the cutoff.

tm-6 should only be trimmed so that u have 5.333v @ j4.

try tm-3 first otherwise u want to play with transistors.

[rarara]

think TM6 was the only thing I tested during my build, since I could use my meter.

think i will try TM3, and additionally the proper method for getting TM4 and TM5 exact. does anyone know of a good android tuner app which will show me a lowC and a normalC together to allow me to set the width??

[DCY]

By the way, by tweaking the TM3 pot, does it only affect the cutoff offset of the VCF, or the cutoff range? Or is the character of the filter also slightly altered by tweaking TM3?

[aminoacid]

any tuner will prob do! i use guitar tuners, there are for sure free vst´s for your DAW.

trimming tm3 is just like tweaking the cutoff knob, same range. but perhaps if u change the cutoff pot (vr3) to a higher resistance, youll gett a higher swing.

[DCY]

Aha thanks, so for example if I turn TM3 clockwise, the lowest end is brighter and the highest end is even more bright.
And if I turn TM3 counter clockwise, the lowest end is more cut off (more low end) and the highest end doesn't reach full brightness. Correct?

(sorry for this quick question in between )

[aminoacid]

yes both ends will follow your turning motions

[Altitude]

If you want to adjust the cutoff range, just replace R47 with a 10K trim pot. This will allow you to adjust the low end of the cutoff to whatever you want (down to silence). TM3 tunes the resonance, it does not affect the range (i.e. it will shift it up and down but the "window" size does not change)

[rarara]

OK, so i fully turned TM3 clockwise and i am already liking the sound difference. it means that the resonance boost (as part of the BCBox i/o-distortion mod) which wasn't really making much difference is now more dramatic

returning to a tuning question from earlier though....

i am using a tuner for the android (gStrings) and am a little unclear on whether I am using it correctly. when comparing the C# and C#+1 it is registering about 65hz and 130hz for each (it may have been 60 and 120 as was done last night ), and D# and D#+1 about 70hz and 140hz. does that seem OK? it was never out by very much

i can't find a tuner to show/record the output peaks, gStrings has a needle so is slightly unaccurate. anyone advise?

[AstralBrainTentacles]

i looked up the notes in a table...

C#2 is 69.30 Hz
C#3 is 138.59 Hz

... sounds like it is off...

im in the drama of tuning mine now...

here is a link to my thread:
viewtopic.php?f=12&t=23947

[Altitude]

The absolute tune is not as important as the span (you can always tweak it with the tune knob), just make sure that C1 and C2 are one octave apart (twice the frequency)

[antto]

+1 Altitude
that's exactly what i'm trying to tell everyone ;P~
tweak TM5 first, till C1 and C2 are exactly 1 octave apart
only THEN tweak TM4 to set C2 according to the reference freq for C2 (or use A4 or whatever)
afterwards you'd just have to use the TUNE knob to adjust the "reference" freq if needed

[xlarge]

Best tip ever.