buddax wrote:Planning to build my third x0x soon, and was just going over what mod's and what transistors I want to socket. For the transistors I'we come up with Q8-Q10 ( maybe Q11 ) and Q28.
Anyhow... I was thinking about just putting all the transistors in the VCO and VCF in sockets... but is there more components that would be interesting to have in sockets?
I would say it depends on how your x0x will be used. If you plan on using it for performances or other events where it will be moved often, I wouldn't put ANY of the transistors in sockets, and precious few of the chips. Of course, you will want to check some of the more rare transistors for functionality before soldering in place permanently. The practice of "tack soldering" a component in place to test before making the job more permanent is not unheard of, and is even recommended in the service manual for the Roland SH-09 synthesizer when matching up BA662A chips in the filter.
If the x0x will be not moved as much, or at all if it stays in a studio, sockets shouldn't be much of an issue if they are good quality. I would suggest sockets for all the 2SC1583 transistors, as you may find that the x0x will sound better with differing 2SC1583 in different positions. In other words, one particular C1583 may noticeably sound better as the buffer in the filter than another, even if they have the same date code. From what I've seen so far, the most critical position is the buffer in the filter (Q21), followed by the input of the filter (Q12), with Q26 in the VCO having the least effect on the sound.
If you have multiple transistors to try for Q28, I'd definitely socket that one, and swap JFETs in and out until I got the best square wave.
Now, if you really plan on experimenting with different transistors, feel free to socket any of the ones you see fit. I plan on doing extensive semiconductor tests in the x0x I'm currently building, so I have sockets for ALL the transistors and chips. I do not, however, have any plans on taking the unit outside the house, EVER!
I hope this helps at least some...
Don Taylor, a.k.a. Brassteacher
"Jack of all trades, master of none, proficient at even fewer..."