MP599 - Mic pre 500 series DOA+Lundahl - DIY Analog Pro Audio
  • MP599 - Mic pre 500 series DOA+Lundahl - DIY Analog Pro Audio
  • MP599 - Mic pre 500 series DOA+Lundahl - DIY Analog Pro Audio

MP599 Microphone preamplifier for the 500 series

$350.93 VAT incl.
$350.93 VAT excl.

The MP 599 is based on one SK99 discrete Op-Amp, one Lundahl input transformer and one Lundahl output transformer.

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The MP599 is based on one SK99 discrete Op-Amp, one Lundahl input transformer and one Lundahl output transformer.

Because of the high performance, mu-metal core Lundahl transformers, the MP 599 features the warmth of the iron but it is also an extremely transparent mic pre that will capture all sound sources with extreme finesse.

The MP599 is great on all transient rich sources like acoustic and percussive instruments. It will shine in close or distant miking applications.

Just install it in your API* compatible LunchboxTM rack and start recording.


    • SK99 low noise, wide bandwith Discrete Op-Amp (DOA) pinout compatible with the API* 2520
    • Lundahl transformers on input and output
    • 66 dB of gain
    • Variable output pad
    • DC servo eliminates linking capacitors.
    • Fet DI input, relay switched, the signal passes through the input transformer
    • Signal/Clip LED monitors signal with full wave rectifier
    • All low level signals switched by relays
    • Golden contacts on relays and switches
    • High grade components throughout
    • High grade double sided PCB with plated holes
    • Available assembled or as a full kit (everything included)

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1 Output Pad: This potentiometer attenuates the output signal, after the output transformer.

2 Signal/Clip LED: Flashes green when a signal is present and turns red 3 dB before clipping.

3 Gain: In combination with the gain switch, this potentiometer sets the total gain between 0 and +70dB.

4 Gain switch: Center and right positions set respectively medium and high gain while left position adds a -20dB pad on the input.

5 Polarity Sets the polarity (phase) of the output signal. Center is a mute.

6 Sends phantom power to the microphone

7 High impedance input (> 1 megohm) for instruments. The instrument signal goes through both transformers.

What's in the kit?

Absolutely everything!

  • Passive components (resistors, capacitors),
  • 2 Cinemag transformers
  • Active components (diodes, transistors, LED, ...),
  • Front panel elements (switches, potentiometers, knobs),
  • Connectors, relay,
  • PCB's,
  • Front panel and side panel,
  • All hardware

You bring the solder (use good quality solder, 1mm diameter max) and the Lunchbox.

Difficulty level

The MP599 kit is an easy build. The DOA is a little more difficult because of the components density.


Specific References

Technical specifications

Measure Conditions Value
Iddle supply current No input signal

V+ : +51 mA
V- : -47 mA

Input impedance f=1kHz 1.4 kΩ
Maximum input level   +22 dBu
Maximum output level before clip f=1kHz +26 dBu
Minimum gain   -15 dB
Maximum gain   +66 dB
EIN Zin=0Ω
-129 dBu
Frequency response Gain=+40dB
Deviation < 1dB
10 Hz - 70 kHz
THD f=1kHz
< 0.007%
DI input impedance   > 1 MΩ
DI gain range   -33 dB to +45 dB
DI max input level   +15 dBu

Sound Skulptor MP573, MP599, MP566, MP599 Preamp shootout for bass guitar


Frans Stummer

Does things other preamps do and then some more

How do you evaluate a preamp? I would sort them between the two extremes of "having no sound at all" and having "a lot of sound". The MP 5.99 has not that much of an own sound. That in itself it neither good nor bad, it just tells what it CAN do versus what it can not. For example, softening a sound or pushing it to overdrive with a gradual slope into creamy, buttery overtones.. it does NOT. The MP 5.99 keeps the input sounding muscular and quick, if it's not a mic on a cottonball, see? Let's have a look at the other end of the "preamp-color-chart", a completely 'transparent' preamp, transformerless on input and output, superfast slew rate, super high bandwidth, etc. etc.: these, albeit toutet as desirable, or "true" or "hifi" or whatever lipstick you want to put on them.. are (at least in my world) close to useless without a tape machine. Why? Because they work well on signals that are already close to perfect sounding and at a good distance. Like an orchestra. Put these type of preamp on a snare close mic in a digital recording and what you get is transient hell, spiky, useless, unmusical, anemic. To make sense with such a signal in a mix needs an iron fist, a compressor, a sledgehammer and time on your hands to get all the work done that gain staging or the right preamp (or the transient-eating habits of tape) would have done for you. Me, I'm lazy. I want the signals to be recorded like they will work in the mix. Making desicions now, not later. Not fixing it in the mix. More work at mixdown? NO.
Here is where the MP 5.99 fills a gap that not many preamp makers even seem to recognize: It is clean AND it has transformers in and out. So you can use it on close-miked sources. Even on very, very loud close miked sources. This preamp can take a beating. Where most other preamps with transformers on input need a pad, (which - depending on the mic - will surprise you with a change in sound as well…) the transformer on the way in with the MP 5.99 swallows (shuffling through datasheets..) 10dBU @ 50Hz with just 1% distortion. That's practically line level, kids. You can even jumper the input transformer from 1:5 to 1:2,5 for a little less gain and more headroom. That's like "more cowbell", just better (if you don't get that, do the search engine) It doesn't stop here - another jumper on the output transformer makes it go from 1:2 to 1:1. I'm not even halfway through and there's already a few features you won't find in 99% of all the other preamps in the world. It has a pad with a potentiometer after the transformer, so you can cook the signal a little on the way in .. and turn the output down after the transformer. (insert a few four-letter words here) (or how about "Holy mackerel, Batman!!") Excuse me, if I get a little technical here, but the folks behind SoundSkulptor were thoughful enough to do an Opamp that is friendly with low input impedance. Yes, because of that it can have a low-ratio input transformer and because of that it can take levels that tear your face off. Bravo! (applause!) Thank you, SoundSkulptor! Not only can I use the MP 5.99 on super loud kick and snare without worries, but also on condenser mics with notorious high output. (which includes the usual U47.. and a few hundred others) With the benefits of transformers inbetween. To my best knowledge, there aren't even half a dozend preamps in the world who pull that off….more like, three others. But even these don't got the output-pad… or the super-duper-handy gain range switch. (biaaatch!) (just for rhyming, okay?) What does that switch do? A) low (=input pad, if your signal is broadcast-level line) B) mid (pure gold!!!) C) high (oh, that's what all the other preamps do anyway) So, why is that switch soo handy? Use it with 'mid' or 'high' and when you play it back, you can use it as kind of a mute button, switching it one down to keep the chatter from the tracking room out.
I already got a few other preamps that can do the 80-dBs-of-gain-until-you-puke without the slightest hint of noise, so putting a ribbon mic on a mouse pissing on a cotton ball and getting that up to 0dB on the A/D with +24dBU is no problem. I got a few mid-gain preamps as well (around 40-60dB) .. and I got a few tube preamps that can go from hifi-clean to a marshall full stack inbetween. I didn't have a beast like the MP 5.99.
It starts with very low gain, not with - for example - already at +30dB you find on other preamps. To sum it up: it's a tool that helps you with tasks where your usual preamps don't go. You could use it as the only preamp on an island as well, but then you would need a pretty long extension for your power strip. Soundwise, all is fine. Let me add that I am spoilt with gear, having preamps by Manley, Telefunken, JLM Audio and a few more and I have been putting up microphones since more than 30 years. Good value for the money.

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MP599 Microphone preamplifier for the 500 series

The MP 599 is based on one SK99 discrete Op-Amp, one Lundahl input transformer and one Lundahl output transformer.

Write your review