The 73P is an authentic, complete adaptation of the vintage 1073®* mic preamp circuitry to the 500-series format. The 73P is authentic in that it uses only components that are hand-selected to match the original, and there are no changes to any of the preamp circuitry. The 73P is complete in that it adheres to the original, three-stage amplifier design. Many current preamps that claim to replicate the 1073® use a two-stage design, which does not have the same character.

The definitive kit

Our guiding principle in designing the 73P was to get everything right. Every choice, from the use of Carnhill transformers to the hue of the front panel, was carefully considered and tested against the original. The 73P even features a unique power regulator circuit designed to replicate the imperfections of the original console power supply.



Know your tools

Our assembly guide makes building the 73P as simple as possible (but no simpler). The 73P is intended for intermediate DIYers who are driven to learn more about how analog audio gear works. The assembly guide is broken down into circuit blocks. Each block features an explanation of how it works and contributes to the sound of the preamp.

Full feature list

• Three-stage mic preamp based on the 1290 preamp, the same found in the 1073® preamp and EQ
• Grayhill 12-position gain switch
• LINE mode turns the preamp into a line-level processor for adding warmth and depth in mixing
• LO Z switch for switching input impedance between 1.2k (standard) and 300 ohms.
• TRIM knob allows for driving the preamp hard without clipping the next device
• Polystyrene and tantalum capacitors in the signal path, as used in the original
• Carnhill input and output transformers
• Front panel DI input. When an instrument is plugged in the mic/line input is automatically disabled
• On-board regulator sets the power voltage to +24 like the original
• Fully compatible with the 500-series format
• Comes with every part needed to complete kit
• Features step-by-step photo instructions, interactive build map, and component sorting sheet
• PCB is divided into circuit blocks, with corresponding explanations of each block in the assembly guide

The full kit is available for preorder directly from DIY Recording Equipment on June 5, 2024 at 12PM EST. diy.re/73p

*The 73P is not designed or manufactured by AMS Neve Limited, owner of the trademarks Neve®, 1073®, and Marinair®.

E.I.N? THD+N?

Thanks for the question. Full specs can be found on the "Specifications" tab here: https://www.diyrecordingequipment.co...-preamp#tabs-4

EIN: -128dBA
THD+N @ 20dB gain*: 0.0032%
THD+N @ 40dB gain* : 0.014%
THD+N @ 60dB gain* : 0.14%
*+20dBu output, 1kHz, 20-20kHz bandwidth

Can't wait !

Been watching this for a while, looks great. Might there be a 500 series 1073 EQ on the way?

Pretty excited about this. Your G bus comp sounds ace. Are you planning to make any sound/video demos?

Also what led you to design the DI as an active fet, vs the kind of design BAE opted for?

I've been studying electronics precisely for a product like this but alas I am too slow. Hopefully my skills will be ready before too long.

Very nice, Peterson!
will probably grab a pair in the near future.

Ditto. I should get a pair this fall or early 2025.

Thanks for the questions. Yes, we'll have demos soon (not before the preorder) and we've also sent a few out to pros to record their own samples.

Regarding the DI, we went with the FET for a few reasons. First, active DIs have a higher input impedance (ours is 1 mega ohm) than passive (typically around 100k ohm). Passive DIs can sound great, but they can struggle to load very high-impedance outputs like passive pickups correctly. This leads to higher distortion and a narrowed frequency response. Second, I just love the way the LSK170 FET sounds and I will use it wherever I can (even though they have become rather expensive). And third, BAE can do the passive, resistor-only DI because of the way they have redesigned the gain switching circuitry. We did not have this option because we followed the original gain scheme, and adding a 100k resistor before the switch would change each gain setting.

Awesome—thanks for such a detailed response. Have you used that FET in anything else or know of other stuff it’s been used in?

Sure thing. The LSK170 is a currently-made version of the 2SK170 which has been the gold standard low-noise JFET for decades. You'll find it in tons of applications that require ulta low noise, like condenser microphones and mic boosters like the Cloudlifter, etc. It also distorts nicely—we use it in the JFT Colour module.

Love seeing DIYRE fiercely cranking out new stuff!

This really looks beautiful too – nice job nailing the aesthetic.

Looks great! Will this be available from Link Audio in Europe at some point?

Super stoked for this. I'm aiming for it to be my first real, formal, planned DIY build (rather than the haphazard stuff I've been dilettante-ing around with).

Love your videos and explanations man, looking forward to learning first hand from your builds.

Just placed an order for one. Looking forward to this build and some sweet sounds! Thanks so much for producing this kit so thoughtfully with attention to detail.

Hi, do you have an updated estimate of when these will ship?

Thanks!

Will be getting a couple of these for sure!

These will start going out in a couple weeks and all of them will ship before the end of the month. Thanks for preordering!

Sweet, thanks for the update! Should be a great learning experience with a huge payoff at the end

So the website said restock on Feb 26th for the longest time. Checked this morning and never saw them in stock and still said Feb 26th. Now the website is saying March 12th.

Did I miss the drop or did it just get pushed back? I feel like I refreshed the page multiple times throughout the day lol