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The Mastering Lab ML-1 Microphone Preamplifier Mic Preamp w/ UTC-LS12X #49522

Availability: In stock



WORKING CONDITION: Excellent- This preamp is in excellent working condition. Just as intended, the sound is Hi-Fi but not sterile. 3-D dimension and full of energy and life. 

 Excellent - Shows light signs of handling and use but otherwise very clean. 


BRAND: The Mastering Lab 


FUNCTION: Microphone Preamplifier 

PRODUCT DESCRIPTION: This listing is for The Mastering Lab ML-1 Microphone Preamplifier Mic Preamp 

This very rare Mastering Labs ML-1 was skillfully crafted by Austin-based tech Robert Mokry. With his permission, we present in his words the story behind this exceptional piece of gear:

"During the prototyping phase, the UTC LS-10X was the mic input transformer benchmark. But they wanted to keep the unit size to one rack space, so ended up choosing a transformer they felt sounded closest to the LS-10X, but would still fit in a 1U enclosure. There were a few one off ML-1s made with LS-10X and LS-12X transformers, housed in off-the-shelf black chassis for some special customers, but none with the original graphics and color to match the 1U units like these. The UTC LS-12X is widely considered to be one of the finest microphone input transformers ever made. These units sound FANTASTIC, and the bass response is unparalleled. If you want to have a piece of gear in your studio no one else has, well here you go.

Earlier units were built with parts left over from the original run that I purchased from one of the designers and developers of the product. I also used those parts as models to make exact reproduction parts, especially PCB's and chassis. I worked very closely with the designer to ensure the preamps came out perfectly. He provided invaluable info to make this project possible. We spoke and emailed almost daily. I also sent him a completed unit to check out and approve - which he did.

I spent considerable time and expense chasing this dragon since 2016. I've been repairing and building tube preamps, microphones, and guitar amps for 30+ years in Austin, Texas. I'm a fastidious, perfectionist kind of guy. These units are built right, a fact I've very proud of.

So what does it sound like? Very clear and hi-fi, but not sterile at all. It's as if the very best of tube and solid-state sounds were combined. THD is .009% at +24dBu with 1K test tone. This is NOT a fuzzy tube mic pre. The ML-1 excels on voices and stringed instruments but sounds great on everything.

The original units are around 25 years old now. They require recapping, replacing the zener diodes in the B+ regulation, etc. You'll have none of those issues to worry about. BTW, I also beefed up the B+ regulation zeners (zener failure/explosion is a known issue with ML-1). The flat-pack power transformers in the original units buzzed physically - it's noticeable if you record in the control room like I do. I had custom toroidal transformers made that exceed the specs of the original flat-pack transformers. No more buzz, and better SNR specs too. The toroidal transformer was also tested and approved by the original designer. All components are top drawer, no expense spared. The original chassis had a tendency to rust. I used metal that is coated and will not rust. Every build detail was scrutinized and improved if possible, without affecting the sound whatsoever."

Robert has offered his contact info to the new owner if they need any technical support for this device.

ACCESSORIES INCLUDED: This item includes a power cable. This item comes only as seen in photos and does not include any other accessories.


UNPACKAGED DIMENSIONS: 19" x 3.5" x 13.5"

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