Gauging Interest in Microphone Circuits

[mdc]

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:

Replacement For Toshiba 2SK170/2SJ74

I've lost count how many times this question keeps getting asked. PLEASE USE THESE DEVICES Linear Systems Matched LSJ74/LSK170 JFET pairs (Grade B) – diyAudio Store J74/J74 Stereo Differential Kit – diyAudio Store Linear Systems LSK170 Ultra Low Noise Single N-Channel JFET (8 Pieces) –...

www.diyaudio.com

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

 

[mdc]

tl;dr - this ebay seller is reputable and sells matched quads:

Toshiba 2SK170 LAB MATCHED QUAD to 0.03mA / 4mV "B" "BL" Idss 7-8mA | eBay

Find many great new & used options and get the best deals for Toshiba 2SK170 LAB MATCHED QUAD to 0.03mA / 4mV "B" "BL" Idss 7-8mA at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[ryan z]

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

Replacement For Toshiba 2SK170/2SJ74

I've lost count how many times this question keeps getting asked. PLEASE USE THESE DEVICES Linear Systems Matched LSJ74/LSK170 JFET pairs (Grade B) – diyAudio Store J74/J74 Stereo Differential Kit – diyAudio Store Linear Systems LSK170 Ultra Low Noise Single N-Channel JFET (8 Pieces) –...

www.diyaudio.com

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]

@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]

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]

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]

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.

 

[ryan z]

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.

 

[brokenwizard]

I'm curious how the circuit avoids passing 48v to the microphone itself which is a feature of commercial versions.

 

[ryanscott6]

For the Cloudlifter, check out this project. SMD components but they are really easy to solder. He even includes a files for 3d printing a case.

FetHead - OSHWLab

In EasyEDA open source hardware lab, open source square pools all kinds of electrical design engineerings together to realize resource sharing easily.

oshwlab.com

 

[bowanderror]

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

 

[brokenwizard]

Amazing! I have a bunch of HRK stuff with some colour modules, I really wish more people would pay attention to it, I think at the moment only DIRYRE, HRK and Louder than Liftoff are making stuff with it.