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76KT SET

76KT SET

What Does the Kraftwerk Audio 76KT Upgrade Set Do?

After extensive research and many conversations with Klark Teknik 76-KT owners through social media and audio communities, several recurring observations appeared in the user feedback.

Many users described the original unit as overly harsh in the upper frequencies, particularly when pushed into deeper gain reduction. Others felt that the stock unit could become coarse when driven harder and that it lacked some of the personality, harmonic richness and liveliness traditionally associated with classic 1176-style compressors.

The Kraftwerk Audio 76KT Transformer Upgrade Set was developed specifically to address these characteristics.

The main objectives were:

  • to reduce the unpleasant upper-frequency harshness;

  • to produce a smoother and more controlled response when the compressor is driven harder;

  • to introduce a richer and more progressive harmonic structure;

  • to add personality, density and musical colour;

  • and to create a more lively and engaging sound compared with the original Midas transformer set.

The upgrade consists of our KO12 input transformer and 5002KT output transformer, designed as direct replacements for the original transformers in the Klark Teknik 76-KT.

How Does This Translate Into Measurements?

The differences between the original Midas transformers and the Kraftwerk Audio upgrade set can be observed in three groups of measurements:

  1. Frequency response – showing how the tonal balance and high-frequency behaviour change at identical signal levels.

  2. Phase response – showing how the two transformer sets behave across the frequency range and how their phase characteristics differ.

  3. Harmonic distortion – showing how the harmonic content develops as the signal level increases from 0 dBu to +20 dBu.

All comparison measurements were performed under identical conditions and at identical signal levels, allowing the behaviour of the original Midas transformer set and the Kraftwerk Audio upgrade set to be compared directly.

Subjective qualities such as personality, density and musicality cannot be described by a single graph. However, the combined frequency-response, phase and harmonic-distortion measurements help explain why the two transformer sets sound and respond differently—particularly when the compressor is pushed harder.

Although the differences shown in the graphs may not appear dramatic at first glance, their audible effect is considerably more noticeable in real-world use—particularly when the compressor is pushed further into gain reduction.

One customer described the result better than we could:

“I expected there to be a small difference, but the difference was enormous.”

The measurements help explain what is changing, but the full impact of the upgrade is best understood by hearing how the compressor responds, saturates and develops character in actual use.


Kraftwerk Audio KT-76 Upgrade Set Installation Guide


The KT-76 Upgrade Set consists of two transformers:

  • KO12 – input transformer

  • 5002KT – output transformer


Before opening the unit, switch it off completely and disconnect the power cable. Installation should be performed by someone experienced in soldering and servicing electronic equipment.

A desoldering pump (solder sucker) is strongly recommended and is essential for safely removing the original input transformer. The transformer pins and metal shielding tabs must be completely cleared of solder before any attempt is made to remove the transformer.


Replacing the Input Transformer


The original Midas input transformer must be removed with extreme care to avoid damaging the PCB traces and solder pads.

  1. Carefully desolder every pin of the original Midas transformer. Use a desoldering pump to remove the solder completely from each hole and release every pin from the PCB.

  2. Inspect every pin closely. Each pin must be visibly free, movable and fully separated from the surrounding plated PCB hole. A desoldering pump may need to be used several times on each connection until no solder remains.

  3. Desolder the two metal shielding tabs that secure the transformer housing to the PCB. Use the desoldering pump here as well, removing all remaining solder until a clear gap is visible between each metal tab and the PCB.

  4. Only after confirming that every pin and both metal tabs are completely free of solder should you attempt to remove the transformer. Do not rely only on melting the solder with the iron while pulling the transformer. The solder should first be removed with the desoldering pump so that all pins and tabs are fully released.

  5. The safest removal method is to grip the metal housing tabs carefully with pliers and gently push them outward.

  6. Do not use force. If the transformer does not move freely, stop and check again for remaining solder on the pins or metal tabs. Use the desoldering pump again where necessary. Pulling the transformer out by force may damage or tear away the PCB pads and traces.

  7. Once the original transformer has been completely removed, insert the KO12 into the existing PCB holes. Install it with the Kraftwerk eagle logo facing upward so that it is visible from above when the unit is open.

  8. Do not remove, trim or reposition the protective plastic collar around the KO12 pins. This spacer maintains the necessary clearance between the transformer and the PCB, preventing metal parts from coming into contact with electronic components.

  9. Carefully solder all pins. Work quickly and neatly, avoiding prolonged heating of the KO12 transformer’s gold-plated pins.



Replacing the Output Transformer


Replacing the output transformer is considerably simpler:

  1. Carefully press the locking tab on the existing 8-pin Molex connector and disconnect it from the PCB. Do not pull on the wires.

  2. Remove the two screws securing the original Midas output transformer to the chassis.

  3. Remove the original transformer and install the Kraftwerk Audio 5002KT in the same position.

  4. Secure the 5002KT using the two existing mounting points and screws.

  5. Connect its compatible 8-pin Molex connector to the existing socket on the PCB. Confirm that the connector is correctly oriented and fully seated.


Before closing the unit, visually inspect all solder joints, the position of both transformers and the Molex connection. After reassembly, functional and electrical testing is recommended before returning the unit to normal operation.

150,00 €Price
If the selected product is currently out of stock, it will be made to order. Please allow approximately 5–7 business days for production.

A Review of the M600 ST + 1366 ST

Heinke Aussenegg (Mastering Engineer Wohlklang Audio)

I have done some work with it since they arrived. Both are great! 1366 a bit more I would say "midrange pronounced" in a musical way. 600STs is more even, balanced, clean and stable.

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But everything in a very subtle way. Bass always stayes very clean although it gets the little weight which is desired. Stood it's ground against the Manley Varimu v4. I prefer the 600ST because it stays more clean in the bass than Manley.

Will often depend on the music and taste but high class anyway. 

 

So thank you again for your work and service!

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Have a nice time and all the best!

​

Heinke Aussenegg,

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Mastering Engineer

Wohlklang Audio
 

A Review of the Kraftwerk 76KT Set

Bo Brocken - Natural Records

Last thursday I received the KT76 transformer set and installed them right away. I ran some tests on vocals and electric guitar.


I was actually expecting to hear some good changes but what I heard, the difference was huge!
The low-end became tight and punchy. The mids much more powerful, stable and a bit creamy (which I really like). The high-end more transparent and less harsh. It sounds great.


I still want to try it on kick drum but so far I really like this mod and I am happy with the result.

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Thank you, Kraftwerk!
Kind regards, Bo Brocken - Natural Records"
 

A Review of the Kraftwerk 1166 VT

Andrew Carpenter (Subliminal Spectrum)

After installing the 1166VT in my Heritage TT-73, the improvement was immediate - the unit simply sounds more alive and musical than before. I wasn’t expecting such a clear step up, but it quickly became obvious in use. It’s rare to find a transformer upgrade that delivers this much character and quality.

A Review of the Kraftwerk 1201 DI Transformer — Passive and Active Configuration

Harry Brehm, Rottweil

Passive Configuration:
I tested the 1201 in passive DI mode, with both primaries and both secondaries connected in series. It was compared directly with a Palmer PAN01 and a Sowter 4243, using a 5-string bass guitar (from low B to high G). The Palmer was quickly ruled out—it lacked the openness and clarity of the 1201 and the 4243.

The 1201 delivered a very balanced frequency response from top to bottom. The low end was full and defined without being muddy, while the highs were clean and open. The entire signal had a sense of clarity and musical weight. What stood out was the way the 1201 handled higher notes on the fretboard—they remained full and rich, much like the sound of a REDDI active tube DI.

I also tried a configuration with only one primary and both secondaries in series, which produced a louder, deeper, and punchier low end with a fast transient response and a subtle growl. This was my favorite setup.

Compared to the Sowter, the 1201 had about 3 dB less output in passive mode, but that was easily adjusted on the mixer. Overall, this transformer doesn’t just look and feel high-end—it sounds that way too. For bass DI applications, I personally prefer the 1201 over the Sowter 4243.

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Active Configuration:
In active mode, I placed the 1201 at the end of a simple tube circuit. The same 5-string bass signal was used, and again it was compared to the Sowter 4243. This time, no gain correction was needed—the output levels of both transformers were nearly identical.

The 1201 retained all the great qualities from the passive test—clear top-end, defined mids—but the bass became even deeper, more controlled, and authoritative. When pushed harder, it produced a smooth, pleasing low-end growl along with a subtle compression that made the playing experience feel more expressive and enjoyable.

Even under high input levels, the transformer kept its sense of air and openness—no harshness or collapse in the treble, and the mids stayed smooth, rich, and harmonically pleasing. Using one primary and both secondaries in series again gave a stronger output without compromising character.

While the Sowter 4243 is a well-known, high-quality DI transformer, the 1201 had noticeably more punch and “muscle” in direct comparison—an excellent trait for bass DI use.

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Conclusion:
The Kraftwerk 1201 DI transformer is exceptionally capable, both in passive and active use. It offers clarity, power, and tonal richness that compete with (and in some ways surpass) established names like Sowter and Jensen. In my setup, particularly for bass guitar, it came out on top. I'm excited for its official release and would be happy to recommend it to others in the bass community, including on forums like bassic.de.
Great work, Goran—this is an outstanding piece of gear!
 

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