My Home Build HiFi Speaker Project

As a Christmas present to myself I purchased a DIY HiFi loudspeker kit from IPL Acoustics. The kit selected was an SM2 Ribbon Mark 2. Chosen for its flat response and smallish size (35 litres).

Given that I worked for 15 years in electronics and radio, I wasn't worried by the electronic part of the build. However the woodworking side was a bit off-putting.

I therefore began with the cross-over filters. The inductors and resistors were provided in the kit and it was suggested that these were hot-glued to the connection panel. I was unhappy with this suggestion and so managed to source some teflon solder posts from connex.

Suspending the components in open-air like this has the added advantage of providing all-round air-cooling. I respected IPL's instructions about keeping adjacent inductors at 90 degrees to each other, in order to minimise parasitic currents. I also used silver solder (4%) for all connections.

Here are some photos of the finished crossover units mounted on the connection panels.

So, now to the woodworking part of the project!

Luckily, I have a friend, Jean-Pierre Boccard, who is a trained cabinet maker and who has a fully equipped workshop. J-P kindly agreed to help me with buying the wood, veneers, glues etc. and also (most importantly!) with the construction.

We went to a local building supply company, Barillet in Dijon, who agreed to cut to shape the mdf panels - J-P said that from past experience they were more accurate at this with their PC-controlled equipment, than he could achieve himself. Of course, this added somewhat to the cost (the mdf panels finally cost 87). However, the pre-cut panels I received were accurate to less than a millimetre.

We were also able to source from this company some really nice beech veneer. Unfortunately I had to buy a 2m x 1m sheet of it, about double the amount I actually needed, which cost 90.

Instead of following the instructions ;-) and simply screwing the mdf panels together, we decided to assemble the panels using biscuit joints. J-P felt this would not only give a stronger final joint, it also had the advantage of making veneering easier. Using screws would have required recessing teh screw heads so that they culd be filled and sanded prior to applying the veneer. As J-P had the required groove cutting machine for siting the biscuits, this was a relatively easy process.

The acoustic foam was glued onto the inside of the panels before assembly. One side, the top and rear panel were covered fully. The suggestion was to leave the base panel and one side panel uncovered. However I was worried about the possible boom-iness this might cause. So I compromised by fitting a 15cm square of foam to the centre of the base panel and a 15cm strip of foam to the side panel.
This decision was also taken due to the complexity of any later changes that might be required. As the units are glued together the only retro-fit option is by working through the holes cut for the drivers. As I didn't fancy the idea of trying to work through a hole to retro-fit foam, I decided to err on the side of caution!

Then the joints were glued and many, many clamps fitted to compress the joints during drying.

After the glue was dry, the clamps were removed and then the holes were cut for the speakers, air ports and connection panels. Once this was done the veneer was glued onto all the outside surfaces, rollered to ensure firm adhesion, then left to dry before being trimmed back with a craft knife.Here is a photo of the finished assembled units.

Now the units were gently sanded with 00 sand paper, then 000 steel wool. Following this around 5 coats of high-quality clear varnish were applied (polyurethane), being sanded back with 000 steel wool betwen each coat. This really brought up the beech woodgrain.

The next step was to clamp the grill panels onto the speakers and drill the holes for the grill panel mounts.

Grill panel GFS mounts fitted.

After this the many, many screw holes for mounting the drivers and connection panels were also drilled.

Then the wires from the crossover filters to the drivers were soldered and the drivers and connection panel screwed in place and the front port glued in place.

Above the connection panels I fitted an identification plaques.

The the almost finished speakers were mounted on some existing speaker stands I had previously built from steel tube and plate and which are filled with fine silica sand.

Now the grill panels needed to be prepared. This involved painting with black paint,

And then covering with the acousticly transparent material provided. The material was simply stapled to the rear of the panels. The right hand photo shows the slightly shiny finish of the material - looks good!

As to the sound quality - these speakers are AMAZING! The key words are detail and balance. The lowest lows are clearly present, bass lines are clear and not lost in a muddy 'boom'; the highest highs are also clear and precise - bells, tambourines etc. sound natural and life-like.

Nothing is over-emphasised, just balanced across the whole spectrum. IPL Acoustics claim that these speakers are sufficiently flat to be suited for use as monitors in a recording studio, where accuracy is the key requirement - you need to hear the music as it really is. Having built and lived with these speakers for a month or so now, I absolutely agree with this claim - these are brilliantly engineered and designed. They are natural and precise and work as well for rock as for classical music.

Having identified the driver units, click on the images to see the data sheets in pdf format;

I looked for prices online and was pleasantly surprised by the very competitive prices of IPL Acoustics. Given that they sell their drivers as matched pairs - a selection process that is complex, time consuming and costly, their kit prices are remarkably reasonable. Really impressed with that.

I should also say that Mr Ivan Leslie - the audiophile guru behind the IPL Acoustics designs - is really helpful. My emails were responded to quickly and with lots of info. All in all it has been a really good project. And now I need to re-listen to all my old CDs and rediscover them!