Small-Fi

[AndrewR]

Hi all,

Thought I'd have a go at building a small system for Scalford, hopefully I will be lucky enough to get a room.

This will include a small chip amp and a pair of single driver loudspeakers. An approach inspired by IG81 from some of the single driver forums.

The chip amp is a souped-up Velleman K4003. I am using a Hammond 266L25 transformer, Panasonic FC power supply caps, a Russian PIO bypass cap and sintered glass diodes (similar to the 47 Labs Gaincard)

The input caps were Wima MKS polyester films, but they sounded rubbish (sibilant and unmusical) and I replaced them with Nichicon ES input caps - which really let the music breath and let through more tone. Wiring is silver and volume pots are Vishay cermet.

The whole amp works surprisingly well. So here's what it looks like:

and here are some pictures from building it:

I hope you like the pictures and eventually the sound.

Hopefully the carpenter to agree to machine the Baltic Birch panels and there should soon be another update on the loudspeaker end.

Andrew

 

[pmac]

I hope you do get a room :^

Lovely to see DIY systems ;-)

 

[gjm]

Looks excellent! I like the clear perspex box, something that wouldn't normally appeal. I hope you get to exhibit.

I saw details of someone over here who was doing something similar. Tang Band drivers in small boxes, DIY class-D integrated amp (about twice the size of a Trends TA10.1), and a battery-powered, SD card reader/DAC for source. Apparently his work meant he was travelling to sites all over the country, staying for a couple of weeks at a time, and he wanted an office system he could take with him.

 

[Fatmarley]

That perspex box looks great.

I know what you mean about those Wima polyester caps. I found them rolled off at the frequency extremes and dull to listen too. MMK polyester are better, but better still are Ansar polypropylene (assuming they'll fit).

Please feel free to tell me to sod off but i'd avoid silver wiring in the signal path. It does something odd to the high frequencies.

 

[awkwardbydesign]

That perspex box looks great.I know what you mean about those Wima polyester caps. I found them rolled off at the frequency extremes and dull to listen too. MMK polyester are better, but better still are Ansar polypropylene (assuming they'll fit).

Please feel free to tell me to sod off but i'd avoid silver wiring in the signal path. It does something odd to the high frequencies.

Some who use and like silver suggest that we have become used to copper, and silver simply lets the treble through more clearly, so it seems odd. I don't have the expertise to evaluate that claim, but I do use silver myself. And polyprops are usually better than polyesters. Of course it depends on many other factors too.

 

[AndrewR]

That perspex box looks great.I know what you mean about those Wima polyester caps. I found them rolled off at the frequency extremes and dull to listen too. MMK polyester are better, but better still are Ansar polypropylene (assuming they'll fit).

Please feel free to tell me to sod off but i'd avoid silver wiring in the signal path. It does something odd to the high frequencies.

Hi Fatmarley,

With the polyesters I was getting noticeable distortion in voices - particularly with sibilance and fricatives. I considered polypropylenes, but as you say, space was a factor. The Nichicon ES caps do a very good job though, particularly with the midrange.

Silver is a very revealing material that seems to work best with analogue sources, maybe copper gives a darker tone to the high frequencies - in a good way.

One interesting thing I have found while doing this and other DIY projects, when soldering and re-soldering it seems to take 2 days for the sound to settle. It could be something molecular going on there.

By the way, the loudspeakers will be small MLTL floorstanders - about 75cm high and using Fostex FF105WK drivers

Andrew

 

[AndrewR]

Just a few other notes on construction.

It turned out that manual tools (including a Tenon Saw) were producing better cutting results than a Dremel.

The acrylic was put together using "plastic weld" - which is not really a glue but a solvent that melts together the acrylic pieces.

To make the box even more "plastic fantastic", I used nylon bolts for the fronts, backs and some of the fittings (I stuck to stainless steel bolts for the transformer and IEC socket). As you can see, I had to tap the acrylic braces - oil helped with that, but the heat that the friction produced when tapping the screw threads was quite surprising.

Getting aligned holes for the pots and sockets was a pain. I ended up printing the placement on paper as a guide and sticking it to the panels.

Using "Wet or Dry" for all the edges is fun.

The aluminium heat-sink was put together from scratch - not really seen that type of form factor used anywhere. It is earthed at the back. The power switch is also earthed, as the manufacturer stipulates.

I managed to source some clear polyurethane feet, which match the box really nicely.

Andrew

 

[Fatmarley]

Some who use and like silver suggest that we have become used to copper, and silver simply lets the treble through more clearly, so it seems odd. I don't have the expertise to evaluate that claim, but I do use silver myself.

You could be right. I like to keep an open mind about these things.

I just found it gave soft, airy high frequencies (sounds quite appealing!) that were a little too soft for my liking. But it also had a slightly hard lower treble. It was like it produced a bumpy frequency response in the higher frequencies.

I only tried Chord odyssey though...

 

[Hornucopia]

Try Zigmahornets!

http://www.6moons.com/audioreviews/zigmahornet/zigmahornet.html

Mine sound lovely, though they aren't 'small' small! Just thin (not in sound though!)

My own Small-Fi uses a Kingrex, iPod and Ziggies.

 

[AndrewR]

Try Zigmahornets!

Thanks for the tip Hornucopia. I already have the Baltic Birch cut for these MLTLs.

Andrew

 

[RobHolt]

Very sweet Andrew.

How about some soft lighting inside the box...

 

[taff]

Looks Ace! Nice one, lots of work in that. Looking forward to speaker updates.

 

[AndrewR]

Looks Ace! Nice one, lots of work in that. Looking forward to speaker updates.

Aye me too. I'm waiting for a quote from a local carpenter to get the wood rebated and holed.

Andrew

 

[sunbeamgls]

Hope you do get to exhibit. Would be good to hear your own speakers, but perhaps an SBT into your amp feeding Q2010 speaks would work well too

sent from a different Galaxy

 

[speedysteve]

Very interesting projects. Hope to see them at Scalford.

 

[MF 1000]

Thanks for the tip Hornucopia. I already have the Baltic Birch cut for these MLTLs.

Andrew

Andrew

I have a pair of fostex (I think they are 105E) that I used is a test pair of zigs last year if you need some drivers.

I'm on holiday till after the bank holiday, so I can't check the exact cost ex model no.....but can do once I return if your interested

Keith

 

[AndrewR]

Thanks for the offers about the Zigmahornets. I already have some quite large loudspeakers, and looking to build smaller ones. The zigmas would be too tall and not fit in the back of the car, if I bring them to Scalford.

The local prototyping workshop didn't seem that interested in machining the pieces of wood, saying that they need to create jigs and could run into 100s of pounds - they must have thought I had "mug" written on my forehead.

I'm getting a carpenter/joiner to machine the wood, but he's made a small mistake already, setting the rebates about 1mm too far back on the front and back. Hmmm its not a disaster, but not really perfect.

Andrew

 

[Fatmarley]

I'm getting a carpenter/joiner to machine the wood, but he's made a small mistake already, setting the rebates about 1mm too far back on the front and back. Hmmm its not a disaster, but not really perfect.

Andrew

I would have machined the rebates back a touch too, to allow for glue and any possible imperfections (it's easy to fit a flush bit into a router and remove the excess,) Assuming he is your average carpenter and doesn't have a workshop with joinery equipment, I wouldn't be too hard on him. Although carpenty and joinery work does merge (some joiners come out on site and hange doors and carpenters get asked to make doors, window or WHY on the odd occasion) building a speaker cabinet is more joinery than carpenty and is better done in a workshop.