LHZ-01 HazLabs Preamp Clone: $140.00 USD

The LHZ-01 has been redesigned for 2024 as is even smaller and easier to install than ever before!
Click here to jump to the new LHZ-03 preamp.

IMPORTANT: The LHZ-01 is being discontinued and will no longer be available. We will continue to support this older version and maintain installation manuals, but will no longer be producing new models now that the LHZ-03 has been released.

The LHZ-01 Bass Guitar Preamp is a faithful re-creation of the circuit used in late 80’s and early 90’s HazLabs bass preamps to create that classic and elusive Spector tone. If you have a 20-year-old Spector NS2A, Euro, or ReBop and are ready to upgrade the stock EMG pickups and TonePump preamp to get that signature NS2 sound, all you need are a set of active EMG PJ pickups and this preamp! 

The LHZ-01 is a component-level clone of the original 80’s and early 90’s HazLabs preamp which was designed to push its opamp into nonlinear operation only during the extreme peak signal transients that occur when the bass is played aggressively.

Played with a normal or light touch, the preamp provides a clean bell-like tone. But, when played aggressively, this preamp provides a subtle tubelike compression and adds distinctive high-frequency harmonic overtones to the sound that perfectly accentuates the Spector growl.


The EQ curves of the LHZ preamps faithfully replicate the original HazLabs EQ curves that augment the unique pickup placement on Spector NS2 basses. On the NS2, Rebop, and Euro bass models, both pickups are closer to the bridge than traditional basses, resulting in slightly lower volume and lower bass response. As a result, players would “dime” the bass and treble controls to compensate… and found the secret and elusive tonal artifacts that keep this vintage preamp design in high demand 30 years later.

The result is a deep (but tight and articulate) bass tone with a distinctive growl, light compression that keeps slap bass transients neatly in the pocket, and shimmering high frequency harmonic overtones that make the bass stand out in any mix. 

EMG vs LHZ Comparison

The LHZ preamps have been designed as a very compact 31mm X 50mm PCB (Printed Circuit Board) that can be installed in the smallest control cavities. The PCB also allows multiple wiring installation variations to allow users to configure their unique volume, blend, and tone controls to suit their needs.


  • One LHZ-01 Preamp with pre-wired Bass and Treble potentiometers (100K Linear Taper, Center Detent) and dedicated circuit board connection pads that provide easy soldering of of existing pickups, volume, and blend control wires,
  • A downloadable PDF Installation Manual (link below) that contains multiple wiring diagrams for common installation scenarios,
  • One 9-volt battery connector with leads.


Looking for the manual? No problem! Click the WIRING DIAGRAMS link in the top menu, or just go straight to the LHZ-01 manual selection page here: LHZ-01 Installation Diagram


This preamp is designed for users with electronics and soldering experience. You are purchasing the LHZ-01 preamp board, Bass and Treble potentiometers, and installation instructions. You will need to connect your components (volume and/or blend pots, pickups, power, and output jack) by soldering connections to dedicated connection pads on the PCB.

We also offer the LHZ-02 version with header pins instead of solder connections for those who prefer to use DuPoint style connectors for solderless assembly and easy connection of EMG pickups and controls. 


“Hey my brother. Your preamp is kicking butt! So many people are noticing and asking ‘what is up with your bass?’ and I tell them about the LHZ preamp.”

JEFF ADAMS (Starship feat. Mickey Thomas, The Rock N Roll Hall of Fame band, formerly of Survivor)

“Just installed your pre into my Euro LX 4, tried it at a gig I do every Wednesday night and it is simply amazing. It is the Haz Lab I’ve been after but always too late to get!

I’m a dynamic player, and with my right hand it gives me 2 1/2 different bass guitars. With the EQ dimed the warm overdrive that kicks in the low mid to low frequencies and the rattle of the high end are an aggressive, artistic joy to behold.

You just don’t get that with a TonePump. Back off with the right hand and it suddenly becomes a very well-behaved former beast. All without touching a knob.

I’ll be getting one for my LX 5 soon.”

LYNN SORENSEN (Heaven & Earth, Bad Company, Paul Rodgers)

“…you knocked it out of the park with this preamp mate! The LHZ has so much more harmonic content and an overall pleasing warmth. It suffers none of the weird mid range resonance of the TP (TonePump) and after quickly removing all of the EQ work that I had to do to the TP the circuit sounded exactly how I had hoped it would! Rich and interesting.”

“First impression: it’s awesome. Compared to my 18V HAZ when both fully boosted yours has more bass. Has (or HAZ) just the that feeling!”

“Sounds fantastic! Thank you so much I love how the bass sounds so far. If you ever decide to build a pedal version of this preamp I would love to get one to try other passive vintage basses that I rather not modify.”

“Preamp arrived really fast, instructions are very comprehensive. Put it in my Euro Spector today, replacing the TonePump. Preamp does everything as advertised – highly recommended!”

“Outstanding. Been looking for a smaller version of this preamp type for a long time, thank you!”

“I got the preamp installed Monday and had a gig Tuesday. I love what I’ve heard so far! Definitely much more clarity than the TonePump. There’s a significant amount of presence in the mids while retaining that punchy tone. Nice crisp lows without any mud whatsoever.”

“On first listen.. just sounds like a Haz to me.. very happy with this”

“I just tried your LHZ preamp in my Euro LX5. Oh, it sounds awesome, like a Spector should sound, it has THE sound for sure! I can’t thank you enough! You saved my bass!”

“I can’t put my finger on just what sounds different, but it’s just got more ~Angry~ which is what I was hoping for!”

TalkBass.com and eBay.com user feedback


Have you replaced your preamp with a LHZ and posted a YouTube clip or audio review of the sound? If so, let us know and we’ll link it! Check out some of these clips from LHZ users: Media and Samples


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