Differential Preamplifier 8×2. Project Balanced Pre-Amplifier

Another **UPDATE** July 28th

Boards are all populated, not tested yet just waiting for a ribbon cable to show up that connects the selector board to the main board.


Bench all setup to start SMD soldering.

Some parts soldered on the first day, then I took a break.

Input selector board.

All done !

**UPDATE** July 25th

Parts are here !! WOOT !!

I stumbled app-on a really nice & simple pre-amlifier. Contacted the maker ( In Canada ) and did some chatting and research, came to the conclusion and ordered the boards. It’s a fully SMD Balanced Pre-amp, so i get to spend a few hours placing one part at a time soldering one part at a time on the boards.

So far I just have the new shiny boards, parts are on their way. Reading over the very well laid out manual, is going to make this build fun and enjoyable. After I have it all built & tested, I’ll be researching around for a custom chassis or draw up and get my own made.

I have also choose not to use the PCB mounted XLR in & out connectors. Instead I’m going to be buying chassis mountable Neutrik ones..

Few pictures ( from their site ) and a direct link to the product.

Raw PCB & selector PCB

Fully assembled kit, from the company, they sell it two versions. BUILT & Un-built.

Product link.

Differential Preamp 8×2

Mini Dayton’s


This project started from surfing youtube. I found a video of a small bookshelf that had huge potential. I already had a pair of Ribbon tweeters sitting on my shelf for the last 10 years so I thought HEY 80$ for a small pair of woofers to build a pair book shelf speakers. SURE !! Why not !! the nice thing about dayton drivers is they show you ALL the data on their site & you can download the data file to use in xsim to design crossover etc etc…

Original youtube link, << Click me !

I bought a pair of Dayton RS100-P-8 thats RS100 P= paper 8 = 8ohm.


Link to Driver !

Link to PDF File
I already had the Aurum Cantus G2Si ribbon tweeters.

Link to PDF data & their site.



Time for some images and drawings.

Cabinet Drawing done in Google Sketchup.

Dayton Rs100-p-8

G2Si & RS100

Orange Measurements..

Have been doing some tweaking on the Orange Bookshelf speakers.

Using the Mini DSP 2 x 4 Balanced version it works pretty well, and much better sounding. ( will post pictures of the unit )

Changing crossover points and eq values is simple and instant.

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From Orange Book Shelf

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D-I-Y Bookshelf HI-FI Spekers

I’ve been working on so many speaker projects it’s not even funny. Ryan from impulseaudio.ca and i have been friends and didn’t even know it since diyaudio.com days.. He and i recently have been working on a few of “my” projects. I asked him to make me a flat pack with his CNC router for my last few projects.

My latest Project is a sealed Bookshelf speaker using a 7″ LDW7 woofer from Creativesound.ca ( awesome driver ) & a fountek NEO 2.0 Ribbon tweeter.

I will post more measurement data and crossover design later on when i tackle that part. For now im using a Minidsp 2×4 balanced version and 4 class a amplifiers to run them..

These orange boxes are just test boxes till I get walnut wood.

So pictures ?

7″ driver


CNC testing for accurate “tight fit ”

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Box done.

First coat & primer on.

Five coats later, could put more effort into making the finish way nicer but not really needed.

Day later after the paint cured and drivers in.

Am I addicted to audio & speakers 🙂 YUP !!!

Thanks again to ryan @ impulseaudio.ca for the CNC MDF pack …

Big Beast’s Update

I finally got some time this week to start doing some prep on my big speakers. Using a Pair of A&E TD15m drivers. They are curved stacked cabinets cnc’d from Bultik burch 18 layer ply.

I had to use a hand punch and manually punch EACH staple down so it’s recessed deeper so I can start filling all the holes.

Next step will be filling all the holes then sanding smooth, THEN i can start thinking about veneer 🙂

Parasound p / SP-1000 Repaired.

When i was really really young and into audio i dreamed of owing a Parasound Pre-amp.

I went searching on Ebay and found one for 199$ 🙂 YES it’s old but it’s a good one. I searched google for hours for photos & information on repairs etc etc and found nothing.

I bought this, thinking it had no issues but it did, that’s ok I have PAPS to help out..

I connected it and it sounded like POOH..

Fixed now though. It had a pair of 2SC3327 muting transistors shorted on the output. After using the scope to hunt the issue down and replacing them all is perfect.. Now to find a remote…

Pictures of the output on the scope,

Front of the unit,

Inside, with a very nice heavily regulated PSU.

AND my messy Bench!

Have to thank my dad for helping me solve the issue and teach me some scope tricks.

Now to poke at it more and do some upgrades change all the op-amps & some caps & resistors.. Maybe cleaup the regulated PSU ….