LATEST (as of May 5, 2023):
My original objective starting out was to build a DIY TLM 193 (K89 capsule with transformerless circuit). However, I've since acquired an actual TLM 193 and had it overhauled. I have nonetheless wanted to deliberate which circuitry to use in case of a future emergency. Accordingly, this project evolved into more of an inquiry and insurance endeavor in case my OEM circuitry does eventually fail. The goal would be to have a PCB design that can be easily bought and populated with minimal components and dropped directly into a TLM 193 in need of a circuit replacement. This thread can also double as a ready-made pool of ideas for any future DIY K89 build (or any capsule for that matter) all in one thread, saving time for non-engineers like me and/or people who might not know where to start with their first build.
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ORIGINAL THREAD POST:
Hello all,
Before reading on, please be kind and consider that this inquiry, however blind, is out of genuine interest in the feasibility of such a project, even if it only ends in discussion.
PREFACE
After some messing around with my NT1 for a while (big shout out to @kingkorg for the flat IR that works very well: Rode NT1 Kit (the black one) Mods) and loving the results, I still have the itch to build a flat-response workhorse from scratch. Particularly a cardioid Neumann U 89 / TLM 193.
I found out about the TLM 193 on Audio Test Kitchen (ATK), and it sounded so super smooth and neutral to me. Probably boring for most people, but I really need a high-quality platform that takes EQ especially well (good dynamic range and high SPL handling should go without mention). Found out it’s basically a transformerless (KM 100 circuit) cardioid-only version of the U 89i. They have the same frequency response in cardioid, and the TLM 193 is half the price of the U 89i.
Here are the frequency response curves for the U89 and TLM 193 respectively:
The U 89 / TLM193 seem to have a following with classical recordists, but it suited the variety of tracks just fine on ATK. I love its unexaggerated character. However, there’s not much at all on either the TLM 193 or the U89 on GroupDIY. Seems like most people love the U87 which now sounds way too hyped compared to the U89 for my purposes. However, I did find a schematic for the TLM 193 (posted below), which is already a big step forward.
In my search on the forums, an additional – and quite possibly the biggest – glimmer of hope: only a few months ago @soliloqueen alluded to wanting to pick apart a K89 capsule after some interest from a few other members (Soliloqueen's k87(k67) and k47 capsules). Judging by everything I’ve read from the other members about her work on other capsules, that would be a much-welcomed offering for a handful of us
All of that said, here is my reasoning for the project, basic build info to get started, and then finally preliminary notes on parts. While I can follow directions and solder very well, I’m not an engineer and therefore need a lot of help and pointers on deciding and sourcing the needed parts.
REASONING
Technical:
A cardioid-only U89 with simple circuitry (i.e. TLM 193)
Flat/smooth/natural frequency response
Simple, robust, discrete, serviceable
Financial:
Not spend $1,500 on a mic
Not spend $1,500 on a mic that is not serviceable
Intangible:
Satisfaction of building my own serviceable workhorse microphone
Satisfaction of saving money by building my own workhorse microphone
BUILD INFO / PARTS:
TLM 193 schematic deleted from this thread and posted in the proper schematic forum HERE
(thanks to @Moby for originally posting it HERE)
Parts:
- K89 capsule (@soliloqueen? Anyone else?)
- PCB (anyone who can design a board, anyone who prints them reasonably)
- Component list (need help)
- Body with suitable headbasket
(I'm not sure where to start and what would be comparable to a U 89 or TLM 193)
(also depends on PCB size, or rather PCB size would depend on donor body?)
Alternatively, source a genuine headbasket (pretty essential) and retrofit it to a donor tube
INITIAL QUESTIONS
1. Even with such a simple circuit, is there any special biasing/adjustments that need to be made? How much of a headache would this be?
2. Is this ultimately a lost cause, and should I simply try to find a reasonably-priced used TLM 193, and consider simply replacing the PCB inside if/when there is a failure?
3. I’m concerned most about consistency and close replication, not a mere approximation to the TLM 193. What I have with the NT1, Flat IR, and some EQ, it’s a very reasonable microphone as is. Perhaps that's reason enough to go the used TLM 193 route and replace the internals if/when there is failure?
Looking forward to everyone’s thoughts!
My original objective starting out was to build a DIY TLM 193 (K89 capsule with transformerless circuit). However, I've since acquired an actual TLM 193 and had it overhauled. I have nonetheless wanted to deliberate which circuitry to use in case of a future emergency. Accordingly, this project evolved into more of an inquiry and insurance endeavor in case my OEM circuitry does eventually fail. The goal would be to have a PCB design that can be easily bought and populated with minimal components and dropped directly into a TLM 193 in need of a circuit replacement. This thread can also double as a ready-made pool of ideas for any future DIY K89 build (or any capsule for that matter) all in one thread, saving time for non-engineers like me and/or people who might not know where to start with their first build.
- - - - -
ORIGINAL THREAD POST:
Hello all,
Before reading on, please be kind and consider that this inquiry, however blind, is out of genuine interest in the feasibility of such a project, even if it only ends in discussion.
PREFACE
After some messing around with my NT1 for a while (big shout out to @kingkorg for the flat IR that works very well: Rode NT1 Kit (the black one) Mods) and loving the results, I still have the itch to build a flat-response workhorse from scratch. Particularly a cardioid Neumann U 89 / TLM 193.
I found out about the TLM 193 on Audio Test Kitchen (ATK), and it sounded so super smooth and neutral to me. Probably boring for most people, but I really need a high-quality platform that takes EQ especially well (good dynamic range and high SPL handling should go without mention). Found out it’s basically a transformerless (KM 100 circuit) cardioid-only version of the U 89i. They have the same frequency response in cardioid, and the TLM 193 is half the price of the U 89i.
Here are the frequency response curves for the U89 and TLM 193 respectively:


The U 89 / TLM193 seem to have a following with classical recordists, but it suited the variety of tracks just fine on ATK. I love its unexaggerated character. However, there’s not much at all on either the TLM 193 or the U89 on GroupDIY. Seems like most people love the U87 which now sounds way too hyped compared to the U89 for my purposes. However, I did find a schematic for the TLM 193 (posted below), which is already a big step forward.
In my search on the forums, an additional – and quite possibly the biggest – glimmer of hope: only a few months ago @soliloqueen alluded to wanting to pick apart a K89 capsule after some interest from a few other members (Soliloqueen's k87(k67) and k47 capsules). Judging by everything I’ve read from the other members about her work on other capsules, that would be a much-welcomed offering for a handful of us
All of that said, here is my reasoning for the project, basic build info to get started, and then finally preliminary notes on parts. While I can follow directions and solder very well, I’m not an engineer and therefore need a lot of help and pointers on deciding and sourcing the needed parts.
REASONING
Technical:
A cardioid-only U89 with simple circuitry (i.e. TLM 193)
Flat/smooth/natural frequency response
Simple, robust, discrete, serviceable
Financial:
Not spend $1,500 on a mic
Not spend $1,500 on a mic that is not serviceable
Intangible:
Satisfaction of building my own serviceable workhorse microphone
Satisfaction of saving money by building my own workhorse microphone
BUILD INFO / PARTS:
TLM 193 schematic deleted from this thread and posted in the proper schematic forum HERE
(thanks to @Moby for originally posting it HERE)
Parts:
- K89 capsule (@soliloqueen? Anyone else?)
- PCB (anyone who can design a board, anyone who prints them reasonably)
- Component list (need help)
- Body with suitable headbasket
(I'm not sure where to start and what would be comparable to a U 89 or TLM 193)
(also depends on PCB size, or rather PCB size would depend on donor body?)
Alternatively, source a genuine headbasket (pretty essential) and retrofit it to a donor tube
INITIAL QUESTIONS
1. Even with such a simple circuit, is there any special biasing/adjustments that need to be made? How much of a headache would this be?
2. Is this ultimately a lost cause, and should I simply try to find a reasonably-priced used TLM 193, and consider simply replacing the PCB inside if/when there is a failure?
3. I’m concerned most about consistency and close replication, not a mere approximation to the TLM 193. What I have with the NT1, Flat IR, and some EQ, it’s a very reasonable microphone as is. Perhaps that's reason enough to go the used TLM 193 route and replace the internals if/when there is failure?
Looking forward to everyone’s thoughts!
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