Sound differences xox vs. 303

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eil
 
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Re: Sound differences xox vs. 303

Post by eil »

I know this is an older post that I'm replying to, but I think some of this applies to the thread as a whole.
but the most significant difference between xoxbox and is the power supply.. sound differences might be possible..
More than possible; we know this to be true. The german noted a long time ago that the 303 power supply was less "sturdy" than the one they designed for the x0x and this contributed to the characteristics of the 303 sound in some ways. He even offered up a couple of mods to emulate the weaker power supply.
i started to wonder if the hard sound i am fighting against might be high freq BANNED that is in the signal on the xoxbox...

the origiunal 303 runs on a much slower internal clock frequency... i think half a MHz... that is a different thing than having something running on 16 mhz inside the little box and another 8 mhz for the usb chip...

this might colour the sound and get espeacially visible on the high freq filtersweeps the 303 produces...

its not so unlikely that my personal problem with the sound is related to that..
Actually, it's quite unlikely. The human hearing range tops out at 18kHz so if the digital circuitry in the 303 operates at 512kHz, you're going to hear none of the local interference that might leak into the analog section. It's even more far-fetched to suggest that 16MHz would affect the analog signal in any audible way.

It's not that I can't appreciate wanting to get the best 303 reproduction possible out of the x0xb0x, but do remember that just as every 303 sounds slightly different, so does each x0xb0x. I personally choose to think of this as a good thing. This gives each 303 and x0x its own character. The nice thing about the x0xb0x is that you can keep hacking it (or building new ones) until you get the sound exactly how you like it, even if it doesn't precisely match a particular existing instrument with exact detail. It's still acid. It's still awesome.

Gaetano
 
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Re: Sound differences xox vs. 303

Post by Gaetano »

I think 3phase is on the right track, using the 'exact' same parts in both. If you want to test one parameter, you really need 'all' of the other variables the same to rule them out. That way it would be easy to see if varying the power supply is the key. Also on the power supply, has anyone tried using smaller reservoir caps, to see if this makes the supply less stiff (someone may have mentioned this I don't know)? This should make the power supply more reactive to loads, although you would not want to use such small caps that the VCO starves and the pitch droops, or maybe this would sound cool as another mod (I have not tried this though).

3phase
 
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Re: Sound differences xox vs. 303

Post by 3phase »

eil wrote: Actually, it's quite unlikely. The human hearing range tops out at 18kHz so if the digital circuitry in the 303 operates at 512kHz, you're going to hear none of the local interference that might leak into the analog section. It's even more far-fetched to suggest that 16MHz would affect the analog signal in any audible way.


This is not entirely true... there can be intermodulation artefacts that go beloe the border of 18k that even when beeing very low in level can colour a sound , maybe on a psychoacoustic level..

But wouldnt be the first time that HF interfearence caused a so alled harder sound...


However... after having a closer look to the 303 circuit board again with the very close by traces and all areas thatn are no traces filled with grounded areas i would assume that there is defenetly a bigger potential of stray capacitys than on the xoxbox board..

So by now i think that this is defenetly part of the phenomen..together with slight part differences as the caps or transistors..

and maybe the power supply..that would be interesting to see at one point what this really does..


One otehr thing somebody of my collegs mentioned...dirt arond FET transistors could alter theire behaviour because even a crossresitance of multiple megaohms allready could effect theire performance.. if tghis could lead to a slightly altred envelope behaviour?

However..a said in my previous mail i work a while with my xoxobox before looking again into the details..

I will post a photo of my xoxed box in the other thread ...
regards,
Sven

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lord.bix
 
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Re: Sound differences xox vs. 303

Post by lord.bix »

Hi =)

i have read the whole thread now 3 times.. now i need the recommendation (i know pretty straight question).. lol. Should i use different green caps or not? If yes,, which are the right ones to place in =)

Regards

/Marco

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mr aize
 
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Re: Sound differences xox vs. 303

Post by mr aize »

lord.bix wrote:Hi =)

i have read the whole thread now 3 times.. now i need the recommendation (i know pretty straight question).. lol. Should i use different green caps or not? If yes,, which are the right ones to place in =)

Regards

/Marco
I would like to second this. This has been a fascinating thread but i'm also a bit stumped. I plan on building a second x0xb0x soon an i'd love to know where and which capacitors people recommend changing. (also where to get them would be very handy :wink: )

toxaco
 
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Re: Sound differences xox vs. 303

Post by toxaco »

bcbox wrote:if you want to try swappign the foil caps I would change only the ones in the audio signal path. C18, C19, 20, C21, C24, C25, C26, C27.

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mr aize
 
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Re: Sound differences xox vs. 303

Post by mr aize »

toxaco wrote:
bcbox wrote:if you want to try swappign the foil caps I would change only the ones in the audio signal path. C18, C19, 20, C21, C24, C25, C26, C27.
Ah yes, but I was kinda hoping someone would have some idea where to get the clear caps from.

3phase
 
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Re: Sound differences xox vs. 303

Post by 3phase »

The clear caps sound better... i am sure of this now...


today i will change the transistors to 2sc 945 as in my real 303 and will see what this is doing..

3phase
 
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Re: Sound differences xox vs. 303

Post by 3phase »

945 !!

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phono
 
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Re: Sound differences xox vs. 303

Post by phono »

3phase wrote:945 !!
indeed, q11 seems to be key here

http://www.ladyada.net/forums/viewtopic ... 12&t=11581

also its worth investigating the tm6 tweak, if i remember correctly i set my 5.33v to 5.84v (that is if cv/gate out isnt important to you, since this will mess the scale up and wont be usable) after doing that to one of mine (complete stock) i can't tell the difference between it and the real 303 we have. It's anyones guess why this happens but it really does make a difference.

3phase
 
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Re: Sound differences xox vs. 303

Post by 3phase »

i also can confirm now that the powersupply is part of the game... and it has a deeper impact than having the original vca
i have put a little 12v lamp with 50 ohm dc resistance in the 12 v supply and it got much closer to the 303 sound..


however .. seeing all the little measures to get the xox closer to a real 303 brings me to the conclusion that nothing sounds like a real 303 except a real 303...

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mr aize
 
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Re: Sound differences xox vs. 303

Post by mr aize »

phono wrote: also its worth investigating the tm6 tweak, if i remember correctly i set my 5.33v to 5.84v (that is if cv/gate out isnt important to you, since this will mess the scale up and wont be usable).
Would it not be possible to change one of the resistors in the path of the cv/gate to get this to work again? I'm afraid I don't know enough about electronics to figure this out myself, but it seems logical. What controls the scale?

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phono
 
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Re: Sound differences xox vs. 303

Post by phono »

mr aize wrote:
phono wrote: also its worth investigating the tm6 tweak, if i remember correctly i set my 5.33v to 5.84v (that is if cv/gate out isnt important to you, since this will mess the scale up and wont be usable).
Would it not be possible to change one of the resistors in the path of the cv/gate to get this to work again? I'm afraid I don't know enough about electronics to figure this out myself, but it seems logical. What controls the scale?
its not that simple, since the cv scale is derived from the 5.33v

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phono
 
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Re: Sound differences xox vs. 303

Post by phono »

3phase wrote: however .. seeing all the little measures to get the xox closer to a real 303 brings me to the conclusion that nothing sounds like a real 303 except a real 303...
which reminds me to reitterate that no 303 sounds like (another) 303 :-P

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isak
 
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Re: Sound differences xox vs. 303

Post by isak »

hi guys

after i read what phono said i decided to replace q11 to 945.
i bought today the 945 transistor :)

my question is if i change any other of the 536 would it make any difference to the sound ?

thanks

Isak :)

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