About the Obsidian

[mbello]

People,

What's the big difference between Obsidian Mosfet and Obsidian Transistor (talking about sound)??
I'm using gringo's layouts, (Bien ahi gringo!!).
Wich one i must build?

thanks so much

[Gringo]

Joe D recommended the transistor obsidian and the mosfet blackfire. I built the mosfet obsidian and transistor blackfire :lol: My favourite of the two is the blackfire, at least until i try the other two versions

Che, los dos tienen ganancia para tirar pa'rriba, para mi gusto el obsidian va mejor con violas tipo strato (sin mods suena GORDO), mientras que el blackfire "stock" suena barbaro con mi LP. Proba y conta

[mbello]

Anybody runs the obsidian with alternative transistors?
(I can't get 2n5089, so i put some bc549),
Bc239 or bc413 may sound better?

thanks

[petemoore]

...there was some typing about alternates to 5089, MPSA18 came up, and YMMV for lower gain types.
 I forget which of Joe's schematics notes read 'please use high gain transistors'.
 Transistor Obsidian...Yeahh !!!

[mbello]

Ok, i finished the transitor obsidian. The problem: in place of heavy metal distortion it's a very-extreme-noise-gated   sound, like a fuzzface with bad transistors. I built it with bc549's.
Anybody happened this?

[Gringo]

Yo lo probe con todos los transistores que tengo dando vueltas, entre ellos los bc549c y suena bien con ellos(me gustan mas los 2n5089, pero la diferencia es muy sutil). Supongo que te fijaste que el patillaje esta invertido

Usaste un pcb o le mandaste placa perforada?

[mbello]

Lo hice en placa perforada, pero lo solucione, era una resistencia que me habia olvidado de conectar una pata.
Suena bárbaro!!!
Que diferencia tienen los 2n5089 a nivel sonido? por ahi con unos bc239c o unos bc423c se la banca bien.

It sound fantastic!! thanks gringo!! and joe davisson, of course.

Gracias,

Thanks!!

[Gringo]

IMO, the bc549c sound "rougher" or "grittier" than the 2n5088/89 i have. Other than that, they work just as good as any other (noise, etc).

Los 549 para mi gusto suenan mas asperos, como mas cortantes, mientras que los 5088/89 suenan mas comprimidos, mas prolijitos, pero ya te digo, es una diferencia muy chica, y seguramente se deba a que el circuito esta diseñado sobre el 2n508x y no sobre el bc... Ademas, los 2N508x que yo tengo no superan los 600 de hfe, mientras que los 549 se van de mambo en ese aspecto.

[vodoochild_ar80]

I mbello, i hope that you share your experience with us in pisotones :wink:

Now i build the transistor and the mosfet obsidian and the best is the transistor if you want a  relly crunch heavy sound the mosfet also sounds good but not as the transistor.

About the blackfire i can't make it work (the mosfet version), i did the gringo layout and not work (change transistors and evriting on the pcb but nothing work), so i use a protoboard but nothing, Exactly the same problem the blackfire is killing my bs250 no matters how many times i change the mosfet but they always die don't know wath could be the  problem.
so mbello try the blackfire and tell me if it worksto you

PD:Che no puede ser todos argentinos en este  foro

[mbello]

Thanks for the info!!

Che voodoo que transistores le metiste al obsidian? voy a probar unos bc239c, de ganancia 600, a ver que onda.

[RDV]

Just remember that the BS250 is a PMOS device that needs a positive ground just like a PNP transistor.

RDV

[runmikeyrun]

I love the culture on this board  

[vodoochild_ar80]

I put a BC550 and also test with some 2N5088 both sounds good (i prefer the 2n5088)i would like to have the 2n5089, probably less noise than the 5088 but same sound.

RDV: when i build the gringo pcb i make that mistake put negtive ground.
But in my board i put pisitive ground, but the bs250 just die just like in the pcb. any idea?  anyone has build the mosfet blackfire that could tell me if work well, i got no more ideas.

[petemoore]

Last night I built an Obsidian.
 Q4 wouldn't bias until I lowered the collector resistor. Schematic called for 10k, I 'tagged' a 4k7 on to the 10k, the collector voltage 'perked up, as did the sound.
 I tried different HG/Low noise types like 5089 and MPSA18's for Q4, but the sound was gated and the collector voltage was very low.

[WGTP]

I built the mosfet Blackfire and it was as cool as the rest of Joe's stuff.  I found with the BS250's I got from Vishay that the bias was a lot different.  I had to change the 2 large resistors at the input of each stage.  Adjust them until you get 4.5v.  It seems this batch of BS250's required rebiasing on anything I tried.   :shock:

Also remember that not only is the battery reversed, the electrolytic caps are too.