Sound differences xox vs. 303

[e:pp:ik]

You guys are gonna start making me socket my caps too!

Interesting read.

[3phase]

I actually really dont have the time for this in the moment... i actually sghould have bought a ready made xoxbox... or just use my real 303 again for live sets...


however... this is quite a lot of feedback regarding the transparent Xicons...

From all what i learned regarding caps during years of refurbishing and moding vintage audio equipment i assume that the dark green Xicons are not the wright type than...

And usually better foil caps give a smoother sound..
The styroflexes in C25 and C27 on my machine imedeatly gave the filter a more singing quality and removed some harshness on the high resonant states... that allready pointed in the direction that the dark green xicons are maybe not good enough to get the fine details of the 303 scream most people love so much about the original machine... My machine sounds much smoother now...but its still not as screaming and bruzzing as my original 303...

however..good enough...maybe one day i try to rebuil the original power supply 1:1...


However.. estimating that the transparent xicons are better than the dark green ones and booth are difficult or impossible to get, it would be necessary to find a propper replacement.
i dont have the time wright now to look into that..

But when i find the time i wouldnt check with wimas.. i maybe would try some vintage style foils from roederstein ( not manufactored anymore) that look very similar to the transparent green xicons...

Or maybe the vintage style foils from tubeamp doctor might be worth testing..they sound smoother than wimas..
maybe not as sparkeling as the vintage roedersteins... but they are availible...

defenetly a point to investgate...

But i realy have to get back to music now... my xoxbox is still in pieces...

I will post a photo when i finaly put it back in the housing... in the winter i can do some more modding

[3phase]

@guest

are you shure somebody mentioned the word polystyrene regarding the transparent Xicons?

I just found that, what would maybe explain that theese things appear only in highend hifi equipment...

Polystyrene Film: The Holy Grail of Film Capacitors, polystyrene has the most desirable electrical characteristics. With temperature coefficients as low as 30-40ppm (special) and typically less than 120ppm (standard), they have excellent linearity of temperature coefficient over the entire temperature range most equipment ever sees on this planet. Dielectric Absorption (.02%) is the lowest found in any capacitor variety. This makes the polystyrene cap the first choice for all critical timing circuits, such as VCO and VCF timings, and for all Sample / Hold circuits. Polystyrene caps cannot tolerate high temperatures (85 degrees Celsius max.), so they are not available in the metallized variety. Careless soldering can destroy them easily, and they are often poorly suited to automated production equipment. There is a persistent rumor that the only manufacturer in the world that made capacitor grade polystyrene film has ceased production. There is still stock in most values on the market, but people are well advised to save a few for top of the line circuits. There are some new polycarbonate caps which will approach the performance of polystyrene.

[3phase]

and one more..

i just found out that the styroflex caps i was testing are a polysteren type... maybe the exess in the high freq range was related to the transistors i selected before in conjunction with the dark green xicons?

At least in the positions C25 and C27 they brought the thing closer to the 303 sound ... hmmm..

My problem is that i tend to be a bit perfectionistic about such details :-/...

i will see if i can get some different polysteren types and see what they do in the filter ladder...

[guest]

im pretty sure that the capacitors in the 303 are polyester
and that they arent high quality
the majority of the parts in the 303 are the lowest quality you can get
and it was an inexpensive device in its day

ive found similar capacitors in televisions and radios
and all sorts of inexpensive electronics

if you do searches for the various capacitor types
polyester is the only type that returns capacitors
that look like the ones in the 303
i think the only difference is that they used a clear epoxy when casting them

i did a full impedance measurement of the x0x and 303 capcitors a while back
using an agilent 4263b lcr meter
and they were pretty similar
i think the 303 capacitors had a bit more resistance
but a lot of these differences could be due to aging effects

[3phase]

maybe..maybe not.. and its not true that roland used the poorest parts available..

MAybe not the most highgrade stuff.. but the dark green xicons are to be found in the cheapest transistor radios of the world and they were build from at least eraly 70´s to now.. they are a standard..and just accidentently all roland machines use transparent ones..

usually a different look indicates a different type.. especialy when they come from the same company that uses the dark green look for a certain type since allmost 40 years now..


Strong indications for a different type in my opinion...


Where you have heard the polysteren story?

I just had a look in my 606 and 303 ..and its remarkable that the foilcabs stay on pretty long legs ...

Is that because the heat resistance problem of polysterene caps?

Its bad that the 606 dont gives values for the 303 filter..otherwise i would like to do a listening test..

but its not really possible to do propper a/b listening on the filter.. you would have to switch 4 caps simultaniously...


I soldered the whole ladder block in with styroflex and the sound was totaly different..so i at least can state that caps in the filtersection change the sound a lot..

and if the transparent ones are a different type they probably give a different sound aswell...

[guest]

i have seen some indications that the green ones are regular polyester
and the transparent ones are polyester film
although im not sure how they could get such large capacitor values
in the xicon caps without using metalized films

perhaps the best thing to do would be to get some old electronics
and take the transparent caps out of it
i have an old tv board here that has over 20 of them on it
including a .22uF
which is the largest cap in the 303
and probably the hardest to find

[3phase]

I found a way to do a test.. the 606 gives 0.01 caps.. i can do a switch test with position C20 and C21..

a coupling stage is probably not as good to hear a difference than a resonating filter.. but if there is the slightest difference to hear its probably a different type...

i might try that...

[3phase]

no old tv´s around..only a broken 606..where i anyway dont mind so much if the sound gets a bit harder or stiffer...
its a machine in a bad shape that is ment for modding one when i find the time to repair it and replace the broken pots..
i would like to have 707style volume sliders for it....

[3phase]

i....
although im not sure how they could get such large capacitor values
in the xicon caps without using metalized films

maybe they are metalized film? they dont need to be polysteren just because it was a rumour somewhere..

But independent how they are actually build...when its a differnt type this would most likely result in a slightly different sound..

opposite to some belives different types of caps have very much a different sound..maybe not in any circuit..

but i found syntheziser circuits extremly sensible to part selection...

I will do the C20 C21 test..just have to find another 0.01 in the 606...

maybe this helps to answer the question..

[guest]

capacitors have a very large effect on sound
as they either let certain frequencies pass or not
so im not suprised to see differences from similar components
and aging effects probably arent small either

i just ripped open a green polyester
and it is layers of metal film and polyester film
im guessing that the translucent caps
have a metalized film instead

[3phase]

i can slaughter one of the transparent 0,01 when i ve finished the test...

so you have a transparent polyster film and a metalized film that run in parallel, wright?

[guest]

i just cut open one of the transparent ones
and it was very similar construction
but it used a thinner film for both the metal and plastic
and they were more difficult to pull apart
although im not convinced that they were bonded to each other

[3phase]

ok..i did the c20/c21 test..and ther is not really a difference between the dark greens and the trabnsparent ones at that position...

on very highfrequent sounds at levels wheer it allready hurts in the ears it seems that the transparents have a slightly thinner sound... but in a so minimal degree that i would count or bet on that..


so probably false alarm

living is learning

[3phase]

i repared my old 303... ell equipped with the insights due xoxbox building and modding i found a bad solder spot that had stollen the low energy rummble of my old 303..


ok..it rummbels again now..and it sounds very different to my xoxbox...

too different..


i am into further investigation..

and first result...

the transparent green caps matter in the filter section...

but they are not the reason for the big sound difference...

the difference is small..but much easier to get than the listening test i performed in a coupling stage...


the tendency is the same..the transparent green ones sound a bit thinner..what results in the resonant filter in a more open shimmering sound.. less agressiv in high resonant filter states than the dark green xicons recomended in the part list...


Because no transparent green xicons are avaible i checked other types ...

cap type in the filter appears strongly in the sound... but i probably will go back to the fark green xicons becuse they are still the closest.. However


i will check against my 303 again ..after i did a VCO out VCF in Mod on booth machines ...