Son of Ben - Preamp

[Elktronics]

I just finished building this one. It sounds great! A little more gain than I was hoping for.

I had to mix and match pot types with what I had on hand, which messed with how I had to solder them all in so they were set at the same height.

I also tried some different enclosed jacks which I got from Cusack Music. I’m not super keen on these. They don’t feel as tight as the other enclosed jacks I used to get. Also not fond of the tiny hole to put your hook up wire in.

I set Q2-Q3 at 4 volts, but was wondering what Q1 should be set at? I currently have it set by ear, but am keen to see what others have done.

Enclosure is a Tayda 125-B in Ball Silver. This color shows every scratch. I feel like I need to wear gloves when I hold these.

 

[Nostradoomus]

Well ya made it work!

Im also not super big on those jacks, I ordered twenty or so of them and the first time I put a cable into it the tip tab bent sideways. No dice.

 

[Elktronics]

I’m thinking of trying some Lumberg jacks for my next build. Those parts weren’t around when I was actively building last. I got some stereo enclosed jacks from Tayda, but they look to be the same manufacturer as the mono ones I got from cusack.

I like the enclosed jacks I get from small bear, but the higher cost and speed to get them puts me off. Although I guess the lumberg jacks are more expensive those too.

 

[Chuck D. Bones]

Nice build!
The build docs say how to set the Q1 trimmer, but setting by ear is as good a method as any.

I have some of those Cusack jacks and they work OK for me. I think the best jacks are the open Switchcraft jacks that SB sells. Can also get 'em from DigiKey.

 

[Elktronics]

Nice build!
The build docs say how to set the Q1 trimmer, but setting by ear is as good a method as any.

I have some of those Cusack jacks and they work OK for me. I think the best jacks are the open Switchcraft jacks that SB sells. Can also get 'em from DigiKey.

Thank you!

I guess I was confused by the 2k notation. I’m setting the trim pot to 2k? I’m not sure why it’s a trim pot if a 2k resistor would get the job done. Is it just one of those things with JFETS where you need that adjustablity to account for how jfets can vary so wildly?

 

[Chuck D. Bones]

The 2K setting is just a starting point. JFETs are highly variable and the trimpots help compensate for that variability. The alternative is cherry-picking the JFETs.

 

[Danbieranowski]

Great looking build! Ironically, I love those small hole jacks .

 

[Elktronics]

Assuming my electrolytics are rated high enough, if I ran this at 18v, I’d probably just need to tweak the trimmers by ear, right? Or would I essentially just want to see 8 volts on the the drains of Q2-3?

 

[Chuck D. Bones]

9V would be a good starting point and then tune by ear. The trimpots may not be large enough. If you're already past the 1/2 way point, then you'll need to increase the trimpots or the resistors in series with them.