0

original 303 power supply
Moderators: altitude, adafruit_support_bill, adafruit, phono, hamburgers

Please be positive and constructive with your questions and comments.

original 303 power supply

by 3phase on Tue Apr 01, 2014 6:54 pm

I made a test with getting the audio circuit voltages 12v and 5,333v reference from a real 303. And i liked it.. I consider it a worthwhile mod i will perform on my xox. But ok..worthwhile for beeing perfectionistic about it.. like buying bigger cpu´s or engraved front pannels.. A luxury mod that is not essential but expensive and nice.. more expensive than nice maybe. But really liked the litle fatter and warmer tone and smoother response i got this way out of my xox..but..the actual sound difference is really small and not really more as what the propper caps for the filter do for the sound.. But its more about the liveness of the sound than the sound quality itself. Its a modulation.. dynamic distortion of the control signas and response ..and its subtile.. but nice..

THe fx is smaller than i ve expected it, and its definitely not the only or main factor that separates the sound of a xox from a 303.. As shorter the loop or recording you make as less audible the difference gets.. its something that fluctuates more in bigger circles than one bar.
It also feels like that the machine reacts more s e xy on the knobs..smoother changes between the various stages a sound ..more liquid..With the xox powersupply it really behaves stiffer..sounds a bit harder on the accents and the patterns do more the same..

In the short loop recordings you dont get that really .. There its just a slight compression on the accented notes.. not really much.. and for this probably not worth the hassle.. but..its one of the factors.. similar strong than good component choices in other areas..but not the magical "turn the xox into a 303" fix.. in this regard a 303 style sequencer does a bigger job for the overall feel..

However. The improvement by the original 303 style power supply is bigger than the audio files tell..its really more the ballistics of the instrument that gets smoother and less edgy than a real change in the actual sound.. more a dynamical thing.

However.. interesting question whether the compression fx can be achieved aswell by modding the xox power supply. But how? The circuit of the 303 power supply looks like a pretty elastic thing that probably cant be replaced by a simple resistor. But does it really need such an rare inductor or is it enough to squeeze more out of a dc/dc converter as it likes to give? IN any case the current limit is probably defined by the inductor and not the following op amp. And therefore the reference should fluctuate under overload condition as well..That results probably in a feedback of accented note to the reference supply.. Since the accent envelope is rather short this modulations are probably hard to measure.. But giving minimal modulation on all control voltages. At least thats what the fx sounds like.
Attachments
longXoP.aif.zip
fzjQQ
(712.84 KiB) Downloaded 62 times
Last edited by 3phase on Wed Apr 02, 2014 12:00 am, edited 4 times in total.
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Tue Apr 01, 2014 6:55 pm

and the 303 power supply
Attachments
long30P.aif.zip
(710.27 KiB) Downloaded 63 times
Last edited by 3phase on Tue Apr 01, 2014 6:57 pm, edited 1 time in total.
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Tue Apr 01, 2014 6:56 pm

and one more
Attachments
HiRes30P.aif.zip
(372.01 KiB) Downloaded 61 times
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Tue Apr 01, 2014 6:58 pm

and the same with the original xox supply
Attachments
HiResXoP.aif.zip
(373.66 KiB) Downloaded 59 times
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Tue Apr 01, 2014 7:00 pm

normal power supply
Attachments
xoxpower.zip
(587.68 KiB) Downloaded 62 times
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Tue Apr 01, 2014 7:01 pm

and the same with 303 supply..you see..the difference is small.. very small.. but when you play it its a fine but tasty difference..
Attachments
303power.zip
(578.62 KiB) Downloaded 71 times
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Wed Apr 02, 2014 1:13 am

kept a bit measuring it.. but my equipment is too bad..just the current draw from this voltage rails is really small.. and the voltage looks stable. Since one can hear the compression fx i guess thats something is going on..current draw is fluctuating..but just in the 0,5 mA range.. 7,5 mA to 8 mA on the 12 V rail..

But..i dont trust that measurements more than concluding tha current draw is in the range the sumida inductor should be able to provide. Voltages vary a little between the xox and the 303 supply..but only 2 mV on the reference and 10 mv on the 12V rail.. not enough to explain the compression fx one can hear.. So i can ony conclude that a 10mA draw is a bigger problem for the 303 power supply circuit as one would suspect
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by aminoacid on Wed Apr 02, 2014 1:56 pm

With the 303 psu circuit i get a steady 5.333v but fluctuations on 12v and 5v.

My
12v line says 100mv dc differance between running and stopped pattern. And up to 50mv ac.

This is recorded with max/min hold on a fluke multimeter.
my machines kills fascists!
aminoacid
 
Posts: 352
Joined: Tue Jun 20, 2006 5:27 am
Location: acidburg

Re: original 303 power supply

by 3phase on Wed Apr 02, 2014 2:52 pm

aminoacid wrote:With the 303 psu circuit i get a steady 5.333v but fluctuations on 12v and 5v.

My
12v line says 100mv dc differance between running and stopped pattern. And up to 50mv ac.

This is recorded with max/min hold on a fluke multimeter.



makes more sense than my measurement since you hear that i fluctuates somehow. The current draw on the reference voltage is very small.around 1 mA.. maybe it is stable.. but also possible that teh fluctuations are just too small and fast to show. MY xox is back on its own power supply now for the time being. Miss the 303 version since it really had an overall smoothing fx.. but am also more satisfied with it since i know now that he difference is smaller than i feared it to be. I will see how the 606 behaves on higher voltages..when i can source a sumida this way i go for the original powersupply circuit..otherwise i probably keep it xox..
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by aminoacid on Thu Apr 03, 2014 12:30 pm

Ill make the same measure when i have a xox with the xox psu.

Im interested about the battery thing. Ive got batteries in my xox but it doesnt run for very Long before it resets.

Im trying to learn about reading/writing avr cpus to see if the reseting is due to fuse settings.

Id love to hear a different (bubbley?) Sound but also make Music in the woods with the 606 and 202.
my machines kills fascists!
aminoacid
 
Posts: 352
Joined: Tue Jun 20, 2006 5:27 am
Location: acidburg

Re: original 303 power supply

by 3phase on Thu Apr 03, 2014 1:44 pm

aminoacid wrote:Ill make the same measure when i have a xox with the xox psu.

.


There is a famous german audio engineers word. " Wer Misst misst Mist.." that suggest to stick ratehr on what you hear than what you measure.. Or..when the measurements dont match what you hear the measurement was flawed or just measuring the wrong parameter.

Since there are litlle sound differences, more fluctuations and a compression x on the accented notes, it should be possible to measure some differences.. But i dont have the equipment to do that and just a fluke is probably not enough.

Anyway.. . I really like it much more with the original 303 supply.. Will build one
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by aminoacid on Fri Apr 04, 2014 9:14 am

Swedish sound techs often talk about german techs and their ordnung in the mix :)

Your right. I just thought that if i measured the voltage lines on the 303style psu id better do it on xox style aswell just to see if thoose numbers had something to say...

I maneged to set the bodvoltage to 2.7v on my xox yesterday. Now Im running on batteries without any reset. So we will see soon what happens when they get weaker.

Bubbletime :)
my machines kills fascists!
aminoacid
 
Posts: 352
Joined: Tue Jun 20, 2006 5:27 am
Location: acidburg

Re: original 303 power supply

by 3phase on Tue Dec 16, 2014 3:37 pm

So i did it… was it worth the hazzle? hardly.. the original circuit is quite complex. And i dont kow if i got it in full fx yet since in the moment it only provides the 12v and the 5,33 refference but not the 5 and 6 volts.

In the original 303 the 6 volt seem to be only for the headphone out amp and the 5V dont need to feed as much electronics and leds as in the xox.

I wonder if that higher power consumption on the 5V might be too much for the 303 powersupply board. but it might have a slight fx to the sound aswell since the accent trigger voltage gives a dc impact on the sound engines enveloping.

shall i try it? however.. just with the 12 and 5,33 volt i ve a pleasing fx on the sound.. its still diferent to a 303.. less noisy for example.. but i need to retune for the new condition to say for sure.. since the sound got smoother now i might have gone to far with other applied smoothing measures i took, to get away from the hard xox sound on high resonances. I can state that the 303 style power supply is smoothing the edge of the envelope on high resonant settings.. i will try how it sounds with more resonance..

The xoxbox.. a permanent building site.. just like the city i live in..
Attachments
IMG_0676.jpg
IMG_0676.jpg (69.69 KiB) Viewed 1140 times
Last edited by 3phase on Wed Dec 17, 2014 3:14 am, edited 1 time in total.
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by 3phase on Wed Dec 17, 2014 3:03 am

The original power supply has no problems with a xox with cpu upgrade. draws between 110 and 120 mA. I cant really say that it makes much of a sound difference to get the 5 and 6 volts from there as well. Not a point to easy a/b.. sounds ok thou.
It definitely changed the sound of the xox. but its still has also a xox character. Its not turning the machine upside down, but you make different things on the knobs. hard to put a finger on.. closed filter sounds are somehow more pronounced. Its a little more bubbly now and less sharp on high resonant accents. Its more a thing that appeals while turning the knobs.. quite similar to the fx you have on plug in emulations versus real analogs. It opens up differently on the filter travels..a little more whisteling.
On static loops the difference seems to almost disappear..you have to listen closley to even get it, the xox pwr supply with 47uf is a bit more edgy and robotic.. the 303 pwr supplys litlle more smear in the highs and wobblyness in the lows adds nicely to the typical filter modulation of the 303. Its smoothing the edges.


To get this done was somehow too much work, cant say if its really worthwhile ( at least without prefab circuit board)
, but i would probably do it again when i have the chance.. might be an idea to make a kit for that mod..but since the sumida rebuild is so very expensive.. I wouldnt pay 50 euro just for that part really.. but sourcing it somewhere else is a hard step.
I got it from a turbo modded 606 that needs a higher voltage supply and therefore had its original supply bypassed.

It definitely changes the sound in a typical 303ísh way. One of the details. but together with the more process jittered event timing of the tb303 you have a little more fluid feel thats typical for the 303. So an expensive little detail but active part of the equation never the less.

However, after having completed the transplantation there is still a difference between my 303 and the xox that is different to the difference between one 303 and the other.. its still less mushy and noisy than the real tb303´s i worked with, what leaves the actual circuit board design of a real 303 the prime suspect for any supposed remaining sound differences. Seeing that the power supply circuit is realized in the real 303 in less than half the space i needed. and that with the highfreq switched power supply circuit not so far from the oscillator section.. Anyway.. that power supply board was my last experiment to get it closer to a real 303..from now on i just tune it to my liking based on the state i ve reached now.. and maybe upgrade the pots and switches..That might do more for a real 303..or even better than 303 feel than most circuit mods.
3phase
 
Posts: 195
Joined: Wed Apr 22, 2009 2:06 pm

Re: original 303 power supply

by aminoacid on Sat Dec 20, 2014 4:29 pm

cool!

do you you realize that you can run the xox on batteries now!?

what transistors did you use?
aminoacid
 
Posts: 352
Joined: Tue Jun 20, 2006 5:27 am
Location: acidburg

Please be positive and constructive with your questions and comments.