DIY AUDIO LDR kit projects

This is my last major DIY project because I have now found THE sound I have been chasing for 50 years.

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The hardest part of the build was to accurately drill and tap 18xM3, 4xM4, 8xM5 holes. I can't even drill two holes the correct distance apart no matter how many times I measure and check.

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STEP ONE

Mount the pre drilled front and back panels to the ends of the Conrad heatsinks. Drilling instead of tapping allows some adjustment for errors.

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STEP TWO

Amplifier components were placed inside the case and moved around until the best position was figured out. The transformers, which are heavy, were centred in the enclosure for balance. The transformer lead lengths determined the position of amp modules and power control module.

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Mark chassis mounting points for power control module and toroidal transformers with a spring punch. Mark the position of the amp modules with masking tape so you know the correct position when using the perspex template.

 

STEP THREE (Drilling & Tapping)

 

To overcome my measurement inadequacies I decided the only wound be to make make a jig from 3mm perspex scraps.

 

1. Bluetak was placed on the blank template and the pcb spacers were pressed into it then carefully removed. A spring centre punch was used to mark the drilling points.

 

2. The output transistors and sensor drilling points were marked after drilling the spacer holes and mounting the board, by spring punching through the output transistor mounting holes.

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3. After removing the heatsinks from the case, use masking tape to hold the perspex template in place. Make sure the amp module is the right way up so that connecting tabs can be accessed from the top.

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4. Use a drill press to drill 2.5mm holes about 6mm deep for the 3mm tap if you don't buy a matched set. Bunnings have good Australian P&N sets for around $10.

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5. Once holes are drilled, remove the template and insert the tap in the drill press and UNPLUG from wall. Spray the tap and hole to be drilled with WD40 lower the chuck slowly clockwise and gently while rotating the tap until the thread is sufficient for your screws. DON'T FORCE IT or the tap will snap. Do the opposite to unscrew the tap by keeping slight pressure on the press handle as the tap comes up.

 

COMPONENT INSTALLATION

 

1. Install amplifier modules on the heatsinks before bolting the case together. This makes it easier to screw the spacers into the heatsink and attach the boards to the heatsinks. Once this is done, sit the silicone washers over the holes for the output transistors and sensor.

 

2. Sit the amp board on top of the spacers and align the holes but make sure the silicone washers don't move.

 

3. Loosely screw each M3 screw through the board holes into the spacers. When they are all in place, tighten them. Then screw an M3 screw through the holes in the board through the output transistors and sensor. Tighten firmly but not too tight.

 

4. Mount the toroidal transformers using silicon washers top and bottom so the mounting plate and chassis are insulated from the transformer.

 

TIP: Previously, I have had toroidal transformers that buzzed loudly, so I isolated the mounting bold from the chassis with a rubber grommet and used two layers of silicone washer under the transformer. It seems to have worked because they are as silent as a mouse.

 

5. Mount the power/control board using 4xM4 screws.

 

CONNECTIONS.

The only connections that MUST be soldered are the amp signal inputs on each module, mains power input and the RCA inputs plus output connections to the HPA-SS/Relay modules.

 

Speakers connectors on the amp module use spades, so does the power/control module. The amp outputs must be soldered to the SS/Relay board.

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TIP: Use Heatshrink Tubing with Glue Lining 4:1 - 6.0mm from Jaycar to insulate spade connectors.

 

The HPA SS/Relay One is designed to be screwed directly to speaker posts with a 19mm pitch. Posts can be in pairs or singles.

 

NOTE: If your case binding posts have a larger pitch than 19mm as mine have, the module can be bolted directly to the minus post and the + hole soldered and or screwed into the + binding post using thick copper wire. (See photos)

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Power Controller R4 is connected to amp modules and power transformers using spade connectors.

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Momentary 12volt ON/OFF switch and optional LED connects to screw connectors on the board using the enable LED pins. 

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DC Offset and Enable connections on the right side of the Power Controller R4 connect to the SS/Relay board.

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OPTIONS

RCA connectors. I decided to use KLE Copper Harmony RCAs from SoundLabs Group and ETI speaker binding posts from Decibel Hifi.

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You can buy cheaper ones, but this is my last project so why not do it properly instead of just ducking over to Jaycar?

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Anthony Holton provides schematic connection guides with his modules which makes connecting internal wiring very fast and pain free if you make up your spade connector leads in advance.

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Anthony suggested some DIY modules, including the one I used will be discontinued soon, so get in now if you are buying DIY parts.

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I had a few quality control hiccups with a couple of boards but that is history and I now have the most enjoyable audio system I have ever heard.

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This is my second Holton build. The first one was replaced by Hypex nCores. Would I build another Holton?

 

NO. I learned my lesson when I sold my first Holton and this one is a keeper.

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For a total cost less that $1800 with premium parts it's a no brainer to me.

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Power up time and sound was pure Holton Precision. Powerful, dynamic, solid accurate musical bass and 3d imaging. Very relaxed and unstressed at any level with a totally silent black background.

I am delighted to be back. EXCELLENT!