Gauging Interest in Microphone Circuits

mdc

Well-known member
I am an idiot when it comes to jfet. It seems the 2SK170BL is hard to find. What is a suitable replacement here?
Here's a 51-page thread answering that question:

Wow, 63-pager actually. JFETs anger up the blood I guess.
 
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ryan z

Member
Here's a 51-page thread answering that question:

Wow, 63-pager actually. JFETs anger up the blood I guess.
Saw that thread. Made me glaze over and also happy that this forum is much more inclusive and friendly, instead of bullying newbies. Thank you!
 

ryan z

Member
@ryan z here's the schematic for the triton fethead; it's about as simple as a circuit as you could imagine, and you could easily put it together on vero. The XLR connectors are probably 10x the cost of the components.

View attachment 13764
I've got this thing underway finally after findeing the SK170s. Where to you suppose I run that GND to? The tab on the xlr socket, to the enclosure, or to PIN 1?
 

bowanderror

Active member
I am an idiot when it comes to jfet. It seems the 2SK170BL is hard to find. What is a suitable replacement here?
Unfortunately, high-transconductance, low-noise JFETs are like unicorn blood these days, so you'll likely have to pay good money. The SMD version is/was 2SK209BL, but you can also try BF862, or if you're OK with an SC-70 package, 2SK880, 2SK879, & 2SK932.

The best current-production option is the Linear Systems LSK170B, or even the LSK389B as you're using them in pairs anyways. Expect to pay $3-5 per FET channel, even for the dual package. The biggest downside to the Linear Systems versions is that they are hard to find. You can find them on the DigiKey Marketplace, but there is a minimum order of 10, and shipping is an extra $10.
 

Bricksnbeatles

Well-known member
Seeing this thread pop up again reminds me that I still need to find some parts for the old Soviet military mic that I’ve had sitting under my workbench for 5 years…
 

mdc

Well-known member
I've got this thing underway finally after findeing the SK170s. Where to you suppose I run that GND to? The tab on the xlr socket, to the enclosure, or to PIN 1?
I think as they're all going to the same place eventually it shouldn't really matter? I know there are a few audio circuits that are extremely fussy about not having continuous ground between stages, but I don't think this is one of them... I could very well be wrong though.
 
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ryan z

Member
Super simple mic booster. Thanks for the schematic @mdc !! I need to tidy up the ground situation, but other than that I am stoked, and it works as it should. Next one will be cleaner. drilling holes for the XLRs was a pain on this tiny enclosure. Graphic and naming by my 7YO.
IMG_1595.JPG IMG_1596.JPG
 

bowanderror

Active member
I've built some of the DIYRE stuff. Easier than a pedal but way more expensive. I really want to mod one of my mics but can't get my brain around a $150 capsule
I've also really enjoyed the DIYRE Colour Palette stuff! I appreciate that they open source most of their designs as well as I've learned a lot through simulating & breadboarding them. Some of those Colour Module circuits just sound amazing for how simple they really are.

Unfortunately, a lot of the cost for full 500-series builds is in the bipolar PSU, balanced IO circuitry, transformers (if any), and mechanicals (rack/panel/switches/etc.). I have a low-cost stereo perfboard Colour Palette housed in a cookie tin that looks ugly, but still sounds amazing.

I've also played around with making a pedal Colour Palette host, see this DIYS thread for more info. I need to improve the design though, because I realized my post-module attenuation solution is probably loading down the module output too much :(

Colour Palette Pedal v3.5 Schematic.png
 
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