# Gauging Interest in Microphone Circuits



## brokenwizard

Hey folks love this community. Some very creative people! I know this is mostly a guitar pedal focused kinda place but was wondering if anyone had knowledge on mic pre / compressor circuits etc. I'd love to build a relative budget channel strip type thing for podcasting etc but really lack the design expertise to do so. I figured I would put the feelers out to see if there would be any collaborators interested before putting up more in depth design ideas that we could turn into a community design.

Edit: Also interested in converting pedal PCBs to line level / post mic pre if anyone wants to weigh in on that.


Cheers!


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## Bricksnbeatles

I’d be interested in muc projects if they were available, but I don’t have any expertise that I could offer— the most I’ve done is restoring some old dynamic mics


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## jjjimi84

The most I have delved into it is replacing broken mics with micparts.com stuff and then building a seventhcircleaudio rack for myself. Great stuff but gets pricey fast.


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## Feral Feline

It'd be cool if there were some DIY Mic projects here.

These are some of the ones I've looked into, but haven't acted upon... (cut n paste from my DIY studio doc)

BUMBLEBEE DIY PRO AUDIO
Uncategorized, Ribbon Mic DIY Kits, Ribbon Mic DIY, Parts, Pro Audio DIY Kits, Accessories, Tools
Mic Pres,  DI s, mics...
     BUMBLEBEE PRO RIBBON MIC RM5
www.bumblebeepro.com/rm-5-diy-ribbon-mic-full-kit/

DIYRE
https://www.diyrecordingequipment.com Home of the colour
500 RACK:
OLA5 Opto Compressor From $300.00
EQP5 Passive Equalizer From $200.00
PR502 2-Slot 500-Series Chassis Kit From $150.00
Colour 500-Series Palette mkII From $150.00
CP5 Colour Mic Preamp From $150.00
500EXT 500 Series Extender Kit $20.00
OLA5 Horizontal Front Panel $15.00
500-Series Aluminum Blanking Panel $5.00
COLOUR PLUGINS
DIYRE
RM-5 Ribbon Microphone Kit $299.00 sale $250.00
RM-6 Ribbon Microphone Kit $350.00
SM-28 Shock Mount $35.00
SB-30 Stereo Blumlein Bar $25.00
L2A, L4A
[some of the above pricing may be out of date]


www.vintagemicrophonepcbkit.com/
Vintage U87i










						Mic & Mod - DIY Microphone Kits & Microphone Parts
					

ll➤ Welcome to Mic & Mod ✅ The 1st Website for DIY Microphone Kits & Microphone Parts. Build now your own vintage microphone !




					www.micandmod.com
				













						Microphone-Parts.com
					

We offer large-diaphragm condenser microphone capsules, circuit upgrade kits, DIY microphone projects, and related audio parts.




					microphone-parts.com
				





Other studio related DIY:
DIY BASS TRAPS/ACOUSTIC TREATMENT







SOUND SKULPTOR  500 series mic-pres, comps, eq, tape-sim


HAIRBALL AUDIO
    Looks like GOOD STUFF! Seattle-based Co focusing on quality components/builds.

    500 series & rackmount


GYRAF DIY
http://gyraf.dk/diy-projects/ 
    GYRATEC G9 – DUAL MICROPHONE PREAMP 
    GYRATEC G10: STEREO VARI-MU COMPRESSOR 
    GYRATEC G14: STEREO PARALLEL-PASSIVE EQUALIZER 
    GYRATEC G21: MAGNETO-DYNAMIC INFUNDIBULUM [PARALLEL/PASSIVE EQ] The G21 is kinda an elaboration on our G14 parallel-passive eq – the parallel topology enables multi-band control without running into the traditional problems in multi-banding. 
    GYRATEC G22: STEREO/DUAL/MS VARI-MU COMPRESSOR G22 is an elaborated and dualified version of our venerable G10 vari-mu compressor. It can be set to dual-mono, but still keeps a backwards-compatibility “G10 mode” where one set of knobs controls real stereo, like you’d want most of the time in mastering.

    GYRATEC G23: “AMBLER” TILT EQUALIZER (DISCONTINUED, see G-23s below)    The G23 was a Tilt-type Equalizer aimed mainly at mix and mastering – for the situations where you had a mix that’s already nearly-perfect balanced, but you wanted it a tad darker or brighter without messing up the overall definition.

    GYRATEC G23-S: “AMBLER” TILT EQUALIZER W/ SOLID-STATE OPTION   The G23-S is an elaboration of our G23 Tilt-type Equalizer, where we added a selectable option for either solid-state or tube audio path.   Like the standard G23, it’s aimed at the situations where you have a mix that is already nearly-perfect balanced, but you want it a tad darker or brighter without messing up the overall definition. This unique tilt equalizer works by distributing the uneven phase response associated with filtering across the whole audio spectrum in stead of having it all within one octave like on ordinary first-order tilt filters.



    GYRATEC G24: “PASSIVE/AGGRESSIVE” CADMIUM COMPRESSOR stereo   The G24 is an entirely new type of stereo compressor – aimed at mix and mastering functions. Like it’s sister and predecessor, the G23 EQ, it’s for those situations where you have a mix that is already nearly-perfect balanced, but you want to control some part of its dynamic without messing up the overall definition.



			https://sonicscoop.com/2016/01/26/diy-gear-review-t-12-microphone-kit-from-microphone-parts-com/
		



_CAVEAT EMPTOR_
I ordered a couple of EQ PCBs from PCBGrinder and never received them (in Hong Kong). Contacted the guy, said he is reluctant to ship a replacement set to China because he's lost parcels a few times. I wanted the PCBs so I told him to send them to my Canadian address, but after 2+ years and still no PCBs I'll be happy if I could just get my money back.


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## brokenwizard

jjjimi84 said:


> The most I have delved into it is replacing broken mics with micparts.com stuff and then building a seventhcircleaudio rack for myself. Great stuff but gets pricey fast.



I think that's what I'm interested in here. A lot of the DIY projects available are trying to replicate expensive LA studio gear. But a lot of people who are podcasting or live streaming etc just need a solid circuit that does the job. I'm wondering if even some of the existing guitar circuits could be altered for line level impedance etc.


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## Harry Klippton

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


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## mdc

I'd add JLM audio to the above list of suppliers.




__





						JLM Audio Shop
					

Pro Audio Equipment




					www.jlmaudio.com
				




Some really handy utility PCBs, cool projects, good prices, excellent support. 
As mentioned above, this stuff gets pricy REALLY fast when you start looking at transformers and cases and PSUs etc etc. You're not going to stumble onto a way to make a Neve pre for $50.

GroupDIY is probably the main forum for that kind of stuff, but I've never been able to figure out how to get a join request approved. There's tonnes of info and schematics and troubleshooting/build threads over there (and also it's incredible what people are able to build) to dig through. That said, it has a... vibe. 

Anyway, here's a cool mic pre.


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## mdc

brokenwizard said:


> I think that's what I'm interested in here. A lot of the DIY projects available are trying to replicate expensive LA studio gear. But a lot of people who are podcasting or live streaming etc just need a solid circuit that does the job. I'm wondering if even some of the existing guitar circuits could be altered for line level impedance etc.



Apologies in advance for rambling, but this is basically my day job and I've had too much coffee this am...

I guess the main question would be, as always, what are you trying to accomplish? 

Do you want to a fun DIY project? Is there an issue with your recordings that you're trying to solve? Are you trying to save money on gear? What do you already have on hand? What are you trying to do that you can't get done with what you have? What are the needs of the project?


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## jjjimi84

I have one little nugget of wisdom to add, the best piece of gear purchased for my studio was the materials to build acoustic panels. 

It changed my recordings for the better and was really easy to build and upholster. No matter what you decided to do to build to record with make sure you have it somewhat treated.


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## brokenwizard

jjjimi84 said:


> I have one little nugget of wisdom to add, the best piece of gear purchased for my studio was the materials to build acoustic panels.
> 
> It changed my recordings for the better and was really easy to build and upholster. No matter what you decided to do to build to record with make sure you have it somewhat treated.


Absolutely!


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## brokenwizard

mdc said:


> Apologies in advance for rambling, but this is basically my day job and I've had too much coffee this am...
> 
> I guess the main question would be, as always, what are you trying to accomplish?
> 
> Do you want to a fun DIY project? Is there an issue with your recordings that you're trying to solve? Are you trying to save money on gear? What do you already have on hand? What are you trying to do that you can't get done with what you have? What are the needs of the project?


I want to build some for my podcast collaborators essentially.

I actually own a Presonas Studio Channel and a DBX 286s. They're both great and I use the Presonas Studio Channel for all my vocal work. Even those are probably better quality than a lot of podcasters / streamers need. Basically I think a PCB that would allow a project where a mic pre, compressor and EQ to fit in a 1/2U Box would be a good DIY project as long as the circuits are relatively simple. Most people don't need a Neeve, just a solid input channel.

I trawl GroupDIY a lot but never seem to find how you actually get in on projects either. But yeah, I know a good transformer and case will be almost $100 by itself. But that's ok. Part of the fun is the build.

I found these that seem like a good compliment to a mic pre.

Simple Compressor.




(https://www.circuitlib.com/index.ph...simple-compressor-limiter/category_pathway-29)




(https://circuitszone.com/4-band-equalizer-circuit/)


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## brokenwizard

I know how much work would be involved in developing something like this. I'd love to learn how to design PCBs, been messing around with Dip Trace a little bit.


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## ryan z

Man, if there was a PCB of a Cloudlifter type thing out there I'd be so stoked. Those things seem way overpriced for what they are yet they are such a great gadget. I see the Bumblebee kit, but looking for something stateside.


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## mdc

@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.


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## brokenwizard

Nice, I have one of these for my Rode Podcaster. I might give this a build too.


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## brokenwizard

mdc said:


> I'd add JLM audio to the above list of suppliers.
> 
> 
> 
> 
> __
> 
> 
> 
> 
> 
> JLM Audio Shop
> 
> 
> Pro Audio Equipment
> 
> 
> 
> 
> www.jlmaudio.com
> 
> 
> 
> 
> 
> Some really handy utility PCBs, cool projects, good prices, excellent support.
> As mentioned above, this stuff gets pricy REALLY fast when you start looking at transformers and cases and PSUs etc etc. You're not going to stumble onto a way to make a Neve pre for $50.
> 
> GroupDIY is probably the main forum for that kind of stuff, but I've never been able to figure out how to get a join request approved. There's tonnes of info and schematics and troubleshooting/build threads over there (and also it's incredible what people are able to build) to dig through. That said, it has a... vibe.
> 
> Anyway, here's a cool mic pre.
> 
> View attachment 13752


Yo, just realised. I live in the same city where JLM is based!


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## Feral Feline

mdc said:


> Apologies in advance for rambling, but this is basically my day job and I've had too much coffee this am...
> 
> I guess the main question would be, as always, what are you trying to accomplish?
> 
> Do you want to a fun DIY project? Is there an issue with your recordings that you're trying to solve? Are you trying to save money on gear? What do you already have on hand? What are you trying to do that you can't get done with what you have? What are the needs of the project?



If that's rambling, then my posts must often look like huge tomes, but ones without the scholarly bits... 😸


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## ryan z

mdc said:


> @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


Thank you!!


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## dpsnacks

Replying to show my interest in some generally microphone-related PCBs! I'd put a pair of FetHead things in an enclosure for sure.


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## ryan z

mdc said:


> @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 am an idiot when it comes to jfet. It seems the 2SK170BL is hard to find. What is a suitable replacement here?


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## mdc

ryan z said:


> 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.


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## 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


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## ryan z

mdc said:


> 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!


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## ryan z

mdc said:


> @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?


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## bowanderror

ryan z said:


> 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.


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## 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…


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## mdc

ryan z said:


> 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

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.


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## brokenwizard

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


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## 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 - EasyEDA open source hardware lab
					

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



					oshwlab.com


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## bowanderror

Harry Klippton said:


> 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


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## 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.


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