500 series microphone preamp

This low noise discrete microphone preamp is a further development of the famous German V series preamps. These are known as one of the best in the market. At Abbey Road the V series were used to record songs of big names in the music industry like The Beatles and Pink Floyd. This is the D2O 500 series version, it comes in a single slot format.

The D2O 500 series is the perfect tool for microphones with a relatively low output like ribbon microphones. The single unit preamp is housed in a rugged aluminum enclosure. The portable format is ideal for the new generation of mobile recording interfaces.

Various functions can be selected like hi gain, all Fet, hybrid tube-Fet circuit, creating your own unique sonic character.

 Low noise / low esr power supply

In single ended preamp designs the quality of the power supply is crucial, D2O is fitted with a discrete low esr voltage regulator built with low noise components enabling optimal performance to the amplifier circuit.


switchable transformer ratio / input impedance

By selecting the transformer ratio switch a selection between a 1:1.75 (LO) or 1:3.5 (HI) transformation ratio can be made. Besides setting voltage gain, this also switches the input impedance of the amplifier between 2.25KOhm and 6.25 KOhm. Different transformation rate and impedance selection options are very desirable as they allow for more sonic options from the connected microphone.


selectable all Fet or Tube-Fet circuit

The Tube-Fet switch determines whether D2O functions as an hi gain, all Fet or hybrid Tube-Fet circuit, each with its unique sonic character.


  • Stepped attenuator

  • Phase reverse switch

  • Phantom power

  • Overload indicator

  • Gain D2O all Fet: 70 dB
  • Gain D2O Tube/Fet: 60 dB
  • EIN: -128dB
  • Headroom: 32 dB
  • Input impedance: 2,25 KOhm / 6.25K Ohm
  • Input impedance: 2,25 KOhm / 6.25K Ohm
  • Output impedance: 100 Ohm
  • Input: XLR
  • Output: XLR / 1/4" jack

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User product reviews

Gratulation to the api 500 version! I am testing in very different surroundings different instruments and comparing with different pre amps. Almost cannot find any difference comparing with my V72 congratulations - neither with flute neither with saxophone.

Just a message to say how happy we are with the D2O mic pre. It sounds fantastic and we are using it with many mics. It likes the U87 and the Coles ribbon and make SM57's sound really hot. Great for guitar cabs. So thanks once again and look forward to purchasing some more products from you soon.

Thank you so much for fixing this up for me. I also just got my second D2O V2. I'll be recording drums with them and I will probably be posting on Gearslutz here in the state about how awesome the service has been and also the products. If you ever need to me write a testimonial or a review I would be happy to.

I'm not a hugh studio but I'm a hugh fan of the Triton pres. I've been using the D2O with a Blue Cactus and it sounds awesome on acoustic guitar! Thanks again and enjoy your vacation!

Thank you for your E-Mail! Thats great, Thank you very much! I've ordered an other one yesterday, allready payed. (so i've got one for the company and one for myself) , a friend of mine allready became his units and they are great!
Have a nice day & Best Regards from switzerland dominic

We´ve recently installed the two D2O pres you send. Very pleased with the sound and performance! Liebe Grüße,

Hey! I must say that the triton is used on everything I do.. It works with posh valve mic's and SM58's just as well. I'm thinking about another for a stereo pair .
Cheers Ally

Hi! Today i got to test the d20 against a api preamp, and the owners of the api, was really "scared" how good the d20 sounded.. They will probably order a few in some days... :-) I know one of them want one. He really loved the sound, and it really killed the api.

Just wanted you to know that, the d2o you have made is really good!!!!!!
best, Julian

Dear Peter-Paul and Erwin. We have been receiving very positive feedback on the D02 preamp .. They compared it to they API gear, and in a blind test, the D02 really kicked some serious ass... Beautiful, Thanks.
Best regards Rass.

Hi guys! I use the D2o on every record I do. The combo of old vintage neumann and the fet mode of the d2o is a fantastic match. Make my km54 and m49 sound really sparkling!

Hello Peter,Thanks for all your help! I love these pres, I did a little shootout with them against the A Designs Red, Blue, Chandler Germ, CAPI VP26 and Toft ATB pres and the Tritons are at the top along with the Germ. Great balanced pre, perfect for an acoustic guitar sitting in the mix. I did the shootout with a Blue Cactus.
Thanks again for all your help and for making such an awesome product! James

About the preamps… AMAZING is the word that comes to mind! Very transparent (in a wonderful way) with a defined character. I found interesting that they had more output on FET mode then TUBE mode. My vintage ribbon mics love them…(RCA 74B, SHURE 333 AND ELECTROVOICE V1).

My moving coil vintage microphones (AKG D12, SEINHEISER 411 AND SHURE SM7) came to life and all of them, I must say, RFI and EMI free. The sonic differences between FET and TUBE varied from mic to mic in a very pleasant and sometimes surprisingly way… AMAZING LITLE MONSTERS!!!
All the best. Manny

The D2Os look so cute and tiny that I wanted to take them to bed....but my wife wouldn’t have it!

We got the d2o Module yesterday, really cool! What kind of tube do you have in there? I did a quick listen to it, I like how big and warm it is actually.
Many Thanks, Andy

My name is Ken from USA, and I recently purchased a D20 Tube Fet 500 series preamp.I just finished a 4-day recording session and used the preamp for the first time, for vocals and snare. The preamp sounds fantastic.

"Yo mr. P, I love your Pre!"
As long time fans of Masters of Reality and the man behind the plan, Chris Goss, we naturally were very proud when we learned he likes our D2O pre!

I love my D2O very much!



"How long will the tube last in the d2o preamp by regular use?"

The tube last at least 10 years by regular use and we have replacement tubes in stock.

"Are all d2o preamps similar in sound? "

Yes all d2o preamps are similar in sound.

"What is the impedance of the DI input of the d2o preamp? "

The Input impedance of the DI is 1 Mohm.