Replace R1 in the power supply with 200 ohms?
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Re: Replace R1 in the power supply with 200 ohms?

by altitude on Fri Mar 15, 2013 10:07 am

i dont think it was impact on the sound itself, what i do think it does influence is the how the notes move from one to the other in the sequencer. play a 303 next to the x0x and that will be obvious in one bar

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Re: Replace R1 in the power supply with 200 ohms?

by rarara on Fri Mar 15, 2013 10:25 am

Altitude wrote:
rarara wrote:hmmm, thats the problem with reading these things - nothing is conclusive. there will be plenty folk who will tell you with certainty it is a factor, and just as many who say the opposite.....

what about another 'myth' which i'm sure i read here some time within the past few months (can't find the thread tho) - someone posted that their x0x sounded different (the implication being better) when fed from the CV output of another machine rather than the internal sequncer??


no myth. i ran that test. driving the cv and gate from a 303 vs playing the same pattern had different results. using the 303 to sequence the x0x made them sound identical


interesting - can you just clarify if you mean the sequence sounded the same or the actual tone/sound of the notes??

what i'd like to know is if you had two x0xb0x's would the same pattern be different when playing a) internally or b) via CV? would it be possible if CV somehow made a difference to route a x0x's own CV/gate from out==>in (this probably assumes you have the I/O mod?)
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Re: Replace R1 in the power supply with 200 ohms?

by altitude on Fri Mar 15, 2013 10:57 am

I dont think 2 x0xb0xes would sound different played via cv. The D to A section is pretty rigid. What would be an interesting exercise would be to sample the CV and gate coming out of a 303 and an x0xb0x and compare the two

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Re: Replace R1 in the power supply with 200 ohms?

by antto on Fri Mar 15, 2013 12:07 pm

Altitude wrote:i dont think it was impact on the sound itself, what i do think it does influence is the how the notes move from one to the other in the sequencer. play a 303 next to the x0x and that will be obvious in one bar

you know i can't try that ;]
but if this is true, it should be audiable, right?
i haven't heard such a recording yet

the internal CV(gate/slide/accent) signals are the same (even if the actual circuit has a small difference) the end result is the same
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Re: Replace R1 in the power supply with 200 ohms?

by altitude on Fri Mar 15, 2013 12:56 pm

I have'nt seen any evidence of the internal CV signals being identical and based on my tests with the 303, they are not (albeit anecdotally).

I agree that if the parts are the same it should sound the same but the 303 is different, different processor, different PSU

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Re: Replace R1 in the power supply with 200 ohms?

by antto on Fri Mar 15, 2013 1:28 pm

afaik the difference in the control voltages on the 303 is that it is just a bit more limited, compared to the x0x
the x0x has to emulate that limitation via the firmware

at the end, it matters to get the right pitch/slide/accent/gate signals and their behaviour, and that's totally doable on the x0x, doesn't matter how they are latched from the cpu
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Re: Replace R1 in the power supply with 200 ohms?

by katarakt on Fri Mar 15, 2013 1:37 pm

The oldest myth says it's the sequencer-code in the 303 what makes the 303 outstanding. Within the x0x this is, apart the psu, the most different part comparing the 303 with x0x and i don't think the psu makes much difference to the sound. I'm not an expert, just what i think.
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Re: Replace R1 in the power supply with 200 ohms?

by antto on Fri Mar 15, 2013 3:14 pm

the fact is, if you program the pattern right, the x0xb0x will reproduce the same control signal behaviour as the 303

c0nb0x has a pattern editor which follows the TB-303 notation and converts to x0x format, you can try programming a pattern on the 303 and then program the same pattern thru c0nb0x and compare
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Re: Replace R1 in the power supply with 200 ohms?

by aminoacid on Fri Mar 15, 2013 4:46 pm

Hi Altitude!

Still would like to know how your cv/gate input is wired/functioning.

About caps making differencies. Would you like some wav?
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Re: Replace R1 in the power supply with 200 ohms?

by katarakt on Sat Mar 16, 2013 12:35 pm

antto wrote:the fact is, if you program the pattern right, the x0xb0x will reproduce the same control signal behaviour as the 303

c0nb0x has a pattern editor which follows the TB-303 notation and converts to x0x format, you can try programming a pattern on the 303 and then program the same pattern thru c0nb0x and compare


That sounds interesting. But who have both a x0x and a 303? I haven't heard about c0nb0x, what is it exactly? I'm not often in the forum so i'm a bit outdated :)
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Re: Replace R1 in the power supply with 200 ohms?

by antto on Sat Mar 16, 2013 3:24 pm

katarakt wrote:I haven't heard about c0nb0x, what is it exactly? I'm not often in the forum so i'm a bit outdated :)

alternative to c0ntr0l
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Re: Replace R1 in the power supply with 200 ohms?

by katarakt on Mon Mar 18, 2013 5:03 am

Ah ok, thanks :)
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Re: Replace R1 in the power supply with 200 ohms?

by aminoacid on Sun Jun 23, 2013 3:50 pm

i just thought about the idea of making the right voltage and ampere limitations for the opamp in the psu.

it could be done with a regulator ic but if i would like to make it with a resistor, zener, transistor and perhaps a cap... would this be the right thinking?

the voltage should be about 25.5V and i want it to become 15.7V.

a network containing a 330 ohm resistor and a 0.5W 15V zener feeding the base of a power transistor (a power full one, perhaps with heat sink to prevent some heat). plus two diodes to ground under the zener to lift that zener voltage to get 15.7 after the emitter of the transistor.

voltage drops 0.6V at the emitter, giving me 15.7V just before R1.

the transistor sould be fed by the 25.5V rail.

by doing this - and perhaps change the capacitor after R1 to 47uF as the original schems says - we get the same voltage and ampere limitations for the vcc of the opamp.

this would give the same amplification limitations for the opamps driving task. and create some warble stuff when high reconance is used.


how does that sound?
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Re: Replace R1 in the power supply with 200 ohms?

by 3phase on Wed Apr 02, 2014 12:25 am

that sounds interesting.. because i am pretty sure that the current limit must happen at this point..before the op amp.. Just.. how does the current limit of such a highfrequncy dc/dc conversion looks like? The fx on the 303 sounds not really linear to me.. rather something that really has a slew to it.. Sounds more like side chaining the signal with itself. Maybe its easier to just use teh damn sumida to achieve the goal. On the other hand a ch eap circuit that does the task wold be a more realistic achievement for all xox users. Tech transplant wants 50 euro for one..and finding a good replacement for the zener in the reference voltage is probably not unsignificant too.

Also interesting that a 303 on weak batteries is about the best sound you can get out of one.. In the past we often used batteries on the 303 just because it was better on recordings..

a variable current source would be maybe nice.. maybe i try with a lab power supply if a standard current limiter gives a use full fx..
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Re: Replace R1 in the power supply with 200 ohms?

by altitude on Wed Apr 02, 2014 6:11 am

Look at guest's PSU design in the x0x heart, that should be a good guide to getting a more accurate PSU

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