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5002-A (API 500 Series)

5002-A (API 500 Series)

75,00 €Price
Quantity

Compact 500 Series version of our 5002 output transformer


The 5002-A is a compact version of our 5002 output transformer, specifically designed for easy installation in API 500 Series modules, where available space is limited.

Electrically, the 5002-A is identical to our 5002K and 5002KT models. It uses the same transformer design, winding configuration, core material and electrical specifications. The difference is purely mechanical: the transformer is packaged in a smaller, 500 Series-friendly format.

The 5002-A is supplied with an 8-pin connector and pre-wired cable for straightforward installation. Cable length can be specified and agreed individually when ordering.

Like the 5002K and 5002KT, the 5002-A is based on the classic UA-5002 output transformer used in Urei 1176 Rev. A–E compressors.

Specifications

Specification

5002-A

Turns Ratio

1 : 1

Impedance Ratio

1 : 1

Nominal Impedance

600 Ω : 600 Ω

Primary DCR

54 Ω (bifilar)

Secondary DCR

54 Ω (bifilar)

Primary Inductance

~2.3 H @ 100 Hz

Core Material

CRGO M6 – grain-oriented silicon steel

Core Format

EI-57

Core

Gapped

Feedback Winding

~20:1 ratio, ~45 turns

Feedback DCR

1.52 Ω / 255 Ω

Frequency Response

Flat from 20 Hz to 20 kHz

Reference Measurement

600 Ω source / 600 Ω load

The 5002-A delivers the same electrical and sonic performance as the 5002K and 5002KT, while its compact construction makes it particularly suitable for 1176-style compressors and other designs built in the API 500 Series format.

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!

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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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