Old hobbies die hard. It’s been several years since I’ve actually done any audio related projects at home and have been quite happy with my living room listening setup. Somehow – I think mainly thanks belong to my ex-colleague who was constantly building some amps or speakers – I’ve found the spark again in audio reproduction and things related. Perhaps more on this side of home improvement later…
I recently ended up buying a new set of headphones, as my awful, old and (t)rusty Philips headset from 90’s was finally giving up and my wireless AKG set is way too noisy to really enjoy music with. I haven’t ever had anything that could be considered as a high-end headphones but now I do. I was already aiming for roughly 100 euros price range, but after trying out various models at local store, I ended up with Sennheiser HD-598. Both for how the set sounded and how it was built. Feels and looks like something that is meant to last for years to come. After listening through few records at home I also found out that none of my listening equipment had decent enough headphone output, so I had to build an amp to drive these.
So to the amplifier section. First and simplest choice is single-ended Class-A MOSFET design. These are all over the internet for many decades now, so nothing new invented with this wheel but I’ll share it anyway. For something that is constructed from handful of surplus parts in hand without too much effort for the design, result sounds very good. It has flaws (or points for improvement!) but I very much like the simplicity of this thing. Judged by listening, it is much better than what my amp or CD player has (not to even mention my computer audio card phones output.)
For the design, I had planar FQD1N80 MOSFETs laying around, so this was obvious choice. It’s a planar construction, so it’s well suited for linear operation mode. It has quite high on resistance so it seemed like a perfect and very balanced match for single-ended headphone amplification. For sake of simplicity and low part count (and perhaps lower overall noise!), this incarnation uses resistor instead of current sink.
Tested this through with signal generator and oscilloscope, everything seemed fine from 10Hz – 100kHz sweep. Not too much added harmonics, waveshapes were symmetrical and seemed to match the input amplitude for whole frequency range. Channel amplitudes were even with each other level-wise over whole frequency range without any additional fine-tuning.
Quickly drafted schematic of one channel and AC analysis result in LTSPice. FET model isn’t same as I couldn’t find any close(r) matches from the library. Despite the model, results agree with the quick measurements I made.
Obviously it can be improved in many areas, but this shall serve now as a reference to which I can compare when I try something different. Also a thing to note is that simulation is run into a nice resistive load so real situation is a bit more complicated and even more complicated when extended into SPL’s from those non-ideal headphones. But that’s a different story, Mr. Linkwitz has made some nice notes on modeling speakers. When I have time, I’ll try to craft a spice model of these headphones to play around.
To feed the amp, I’ve also acquired couple of DAC boards based on Asahi Kasei AK4393 chip. First complete amp setup was paired with 24bit/96kHz USB audio card for hassle-free digital out from any PC, AK4393 DAC board and this single-ended amp design. I really do enjoy how it sounds – It’s super silent noise wise and is more than capable of driving my headphones (SPL levels upto painful). Amount of new detail from my records with this setup is overwhelming. So improvement (or change atleast 🙂 is well noticeable.
What I’ve read from various sources, these DACs by Asahi Kasei should be superb for the price. I myself don’t yet have anything else on the matter other than initial listening impressions, but based on that, it’s very well worth the price! But look here for some serious stuff on the AK4393 DAC – Lampizator and Behringer Ultramatch. The site has also plenty of other interesting reading if you’re into Audio and things related, so take a look.
To continue this project, my next target is to build couple of different kind of headphone amp designs (perhaps one push-pull discrete and some nice tube amp design) to test those side by side and perhaps find some differences in how they sound and decide my favorite. One of the DAC boards will also get all unnecessary stuff removed from signal path, so that is also interesting to hear if changes are audible and can it be considered improvement or not.
Aihearkisto: Hobbies
Stuff related to my hobbies
My new bicycle
Long time no blog once again, so let’s start with the latest. Lots of bicycling in last years and in the spring I started to look for a replacement bike, just for sake of trying something new. At first, options ranged from plain carbon road bike to cyclocross and I was having hard time to deciding what I needed. While thinking the matter through it came obvious that – if anything – I’ll need a new commuting bike as that’s what I’ll mostly do, cycle to work and back.
Having tried some of the new aluminium frames I decided that there are now only two possible options to go for a frame – steel or carbon. The new lightweight aluminium frames don’t seem robust enough as they’re made so light that they’re all doomed to fail. Also I feel a bit uneasy of carbon frame but after trying it I could go for a one (but not the cheapest.)
Using the bike for all weather and during winter I’ll also wanted to have disc brakes and also mudguards (+enough spacing for winter tyres) and rack mounts are mandatory. Last item kind of reduces the possible carbon frame options.
At this point there were some good steel frame models from Charge, Pelago, Salsa, Singular and Surly. I also really liked the new Kuningaskulkuri model from Helkama bicycles, but it is lacking frame size options and brakes so I just couldn’t go for it.
Then a question of a drivetrain. Derailleurs I know and there are plenty of nice options available from at least three big manufacturers. But after I saw Rohloff Speedhub for a first time (must have been about 10 years ago), I’ve always wanted to try one. To this day I haven’t gotten over the price to purchase one but now Shimano has made an tempting attempt on oil lubricated IGH – Alfine 11. Here’s also a link to Shimano commercial video in youtube. It’s obviously not Rohloff but the pricetag is less than 1/3 of one and there has been quite a lot of positive ratings for this in the Internet forums so that was a very tempting option. Folks have used these in different MTB builds so the hub should survive plenty of abuse.
And then one day while browsing, I saw that Charge bikes had a perfect looking bike for me. It had steel frame and Alfine 11 hub as drivetrain. Only thing I had to compromise with it was that this model had a flat handlebar. It is not a big issue as I already purchased a set of aerobars for my previous bicycle and being using flat bar for ages I do like the riding comfort.
So here it is, almost fresh from the package. Charge Mixer 11. All steel frame, fork and fenders. Hydraulic disc brakes. It still needs a lamp and perhaps a hub dynamo to power the lights. Also I need to get those aerobars fitted but otherwise all components start to be in place. Also it will get a fully closed chainguard once I find a model that fits my current cogs.
First impressions:
I’ve now only done 100km on this so it’s too early to say anything else but the first impressions and feelings. I like the looks and overall feel of the bike. Frame is very robust and hydraulic brakes are nothing less than awesome! Hub gears seems to work as expected, it’s quiet and shifts nicely once the cable is adjusted properly. Took couple of iterations for me to get it right, even there are alignment marks on the hub, the correct alignment seems to be a bit off from that.
Equipped with 39T cog in front and 20T cog in rear the gear range seems to suit my needs as is. The low end could perhaps be a bit lower for steepest climbs (haven’t tried it yet, but I know where to go to see if it’s actually low enough) – and in the other end going downhill I can shift to the highest gear and it has been enough for now.
Only gripe for now is that the Alfine trigger shifter feels very cheap (as it is). I’d expected a bit more, but if it doesn’t last, it’s easy to change for a better one. Also as I’ve used solely derailleur type gears for my life, shifting takes some time to get used to. It’s very nice that you can shift while not moving (traffic lights etc) so that’s clear improvement but then shifting under load needs more consideration. Hub does shift but noiseless downshift under load seems much easier with derailleur than with this. For now it seems like a con, but perhaps I’ll learn how to do it with this also.
Only time will tell if this does last. Let’s come back to that after winter.
How efficient is bicycling, really?
This is related to some morning coffee talks ages ago, where an ex-colleague of mine was pondering whether bicycling is an efficient way of traveling or not… Well, figures. Kinda tricky to measure and what to compare it to?
Anyway, as I’ve kept some track of my biking for the past year (gps + Endomondo) and even occasionally used garmin forerunner with hrm to see how much Garmin calculated calories differ from the ones approximated with Endomondo – here are some calculations.
So for the past year (July to July), I’ve tracked 2786,87 km and used 5d:16h:25m time as ”Cycling, transport”, which makes average speed 20,43 km/h. That is mostly bicycling to/from work. It includes riding in all kinds of weather conditions and with two kinds of bike (hybrid for ”summer” season and MTB for winter.) It also includes some extra payload for most of the trips (extra clothes, food, parcels from post… you name it.) Disclaimer; my riding most certainly is not from the most efficient end of the spectrum, more from the comfort end. So there would be plenty of room for improvement in that sense.
Anyway, Endomondo calculated calorie consumption for that travel is 92745 kcal – which on the other hand is 388 045 080 joules. 1 liter of gasoline contains roughly 35 MJ of energy, so one year worth of biking has consumed and amount of energy that equals to 11,08l of gasoline.
So, is it much? If you compare it to driving a car, it’s nothing. If compared to the most efficient gasoline powered vehicles – say ones in Eco-marathon – it’s off the scale, I’m defeated! World record is 0,026388 l/100km whereas I would have consumed 0,4l / 100 km of imaginary fuel with my bike. Oh dear, why did I have to calculate this… 😀
But that cannot be the whole truth. First, Endomondo has quite a bit of overhead. At the time of writing I don’t have my notes on this, but If I remember correctly – Endomondo shows constantly at least 10% more burned calories than what my forerunner shows (and somehow I believe it to be more accurate – as it has the heart rate information available.) I might actually be tempted to re-check this in the next few days. Also – as I do this mostly to keep myself fit – the speed and riding geometry are not efficiency optimized in any sense. If I sometimes get my hands on a good road bike, I might check this again from efficiency point of view.
As I started to write this, I googled for bicycling efficiency and came across this article Human power which has a nice chart of approximated calorie consumption / km / person – in which the cyclist is less than 50kcal/km. Endomondo agrees with that, ~520-540kcal for 13,5km.
According to Wikipedia article on Bicycle performance, energy expenditure when cycling is generally 1.62 kJ/(km∙kg). So to compare to that we would get 388045,08 kJ/(2786,87 km*90kg) = 1,547 kJ / (km*kg). That is approximated rider weight only, if we add 15kg for bike + equipment, the expenditure is 1,326 kJ / (km*kg). Which is at least better than generally used figures!
But my point, compared to any commercially available gasoline powered transport, I think cycling and cyclist wins 🙂
Extending bicycling season […and some other things.]
Much of updates missing from this page, so let’s continue with something I was going to write here already during winter, but have somehow forgotten…
Life’s been pretty much all work and no play for the past months, my only real ”hobby” being cycling to work and back – but an important achievement for the year was that I managed to extend the bicycling season almost through the whole winter season! In this case ”almost” was caused by a nasty flu I caught in February, so I missed almost a whole month of winter biking. Also some heavy snowing combined with poor maintenance of roads and mandatory work trips made me use car or bus in couple of occasions – perhaps in coming up winter I’ll have time to make a set of documentary images about how bad the conditions can be.
Distance from my home to work is 14km, which makes round-trip of 28km. Also terrain is quite varying as there’s roughly 80m altitude difference on my biking route and logged elevation towards work is over 160m! I’ve never done such a long and regular biking trips before on winter season – mainly because clothing is quite a challenge for such a varying temperatures and weather. Second important factor was that my hybrid bike that I use during summer, is pain to use in snowy environment. During this winter, I’ve logged ~1200km of bicycling from November to March so excluding February it makes average of 100km/week. Yay for my self, but goal for next winter can only be to make the average higher 🙂
Clothing was actually much easier to arrange than I thought, a set of sports underwear combined with good wind-proof outer layer served me well down to -10 degrees… Colder than that it just means more layers or thicker jacket.
But on to the bicycles, to overcome the limits of my hybrid bike, I equipped my MTB for winter season with some spiked winter tires (and SPD pedals). Succesful approach in a sense, that amount of snow wasn’t an issue anymore. Only time becomes now a limiting factor, on a very bad conditions it would take more than double the time to get to work, so it was not practical anymore… Did a one little test run (~2km) after a heavy snowing, logged average speed of 7km/h, so I turned back and took a bus.
Second thing I recommend for everyone biking in moist or cold conditions, are neoprene shoe covers! What an awesome and cheap piece of gear. Keeps your feet and ankles warm and dry, no matter the weather. I was able to use my ”summer” SPD shoes down to -15 degrees Celsius!
Neoprene shoe covers
Third thing, getting bored of cars trying to run over me, I needed a better light so they can see me better (and I could also use some unlit streets or trails). Light is equipped with Seoul semiconductor led, rated a bit under 1000 lumens with full wattage. There’s a high and low mode, latter being suitable for public roads (being bright enough to be seen – and dim enough not to blind anyone.) Light came with a lithium battery pack, run-time is several hours depending on usage. I had to charge it roughly once a week, run-time being nearly 10hrs in low mode!
Let there be light!
Testing the light But as the snow has already melt there was also a need to service my summer bike. I’ve had my hybrid for almost 10 years now and it has served the time well. I’ve only replaced a rear cassette and chains couple of times, and have logged quite a distance with it. Bike has roughly seen 35.000 to 40.000 km of road, most of it is logged, so the approximation should be quite accurate… It has all original ”Alivio” branded parts in place, excluding the rear cassette. There’s been some noise from the bottom bracket bearings for some time now and also the front sprockets were in quite a bad shape, so I decided to replace the whole drivetrain for this summer.
For the sake of upgrading (and minimal price difference), the replacement parts are now Shimano Deore branded – at least they should be a bit better, but that remains to be seen. Being so many miles behind with the original gearset, I doubt these will last longer.
I’ve never done such a throughout replacement of parts for a bike before, but it was very straightforward. Took about hour to complete, only couple of special tools were required (which are quite cheap). The whole drivetrain upgrade – including a new rear wheelset (hub, rim, spokes, cassette) and tools cost me less than 100 euros. Some pictures of the upgrade below.
Deore Crankset 
Old Alivio crankset 
Old bottom bracket removed 
Installing new hollowtech BB cups 
New crankset in place 
New wheelset Replacing the rear wheelset did more to stability than I had imagined… The old rim must have been very soft, even it didn’t seem so bad. It feels now like a very different bike. Prior to replacing there was noticeable wobble at higher speeds, but it’s now totally gone.
Barefooted!
So, as topic hints it, I am now on my way transforming into a barefooted runner – because I couldn’t find anymore a new running shoe to my preference.
A little background for this:
About two years back I started to witness odd foot problems, after only a few kilometers of running, my soles (or metatarsus) started to hurt. First I thought this was just caused by excessive training, but as it turned out, problems re arrived immediately even after some time off from running. Second guess for the cause was shoes – so I got myself a new pair but that didn’t help much either, it got better, but the pain still existed and came back after running for a while.
At the time, I was using some heavily shock absorbed (and very supportive) running shoes – as they were supposed to be ”the best”. As this episode caused almost a two months pause in running, I had plenty of time to read through Internet and various forums where I came up some interesting topics about similar issues. It was suggested in couple of threads (sorry, cannot find them anymore, so no reference) that similar pain had been caused by too supportive shoes – and because of that, muscles in soles were supposedly in a bad shape and that is why running would cause excessive stress – and thus the pain.
This seemed like a right conclusion so I got myself a pair of running shoes with very little shock absorption (only in heel), laced them loose (so the muscles in soles would have to actively work while walking) and started to experiment how it would turn out. It was suggested also that stepping with forefoot (or mid-foot) would be better style of running with mildly cushioned shoe, so I started to try that out at the same time. Needless to say, the transformation was not instant nor fast, as this stresses muscle groups that had almost never been used before. I started with combined walking / jogging (stepping with forefoot) exercises with loosely laced shoes and it seemed that the pain would stay away.
(Note: Ofcourse this was partly caused by the fact that I was at the time also able to run more than before, because I was in a better shape overall due to active training.)
So on this road I still am, and now would have been time to find a new pair of shoes. I went through all the major large sports stores in region, and found only couple of pairs that would actually meet the specs, and found no pair that would fit! So it seems that only thing you can now get in the form of traditional running shoe, is a heavily shock absorbed model. During this hunt for the new shoes, I of course tried out number of different options and only thing I can say of these is that even walking in them makes me seasick due to the wobbly/jelly feel. Also, the shock absorption layers bend so much, that I’d quite surely break my ankle if I’d happen to land my feet in a bit of wrong position (uneven surface, jump, whatever).
Being desperate, and as I had seen some ads about these minimalist shoes, I decided I could try these out – it was anyway closer to what I had than any of the shock absorbed models I had tried. Even got a nice deal (Stockmann happened to have couple of pairs on discount), so I paid around 50euros for a pair of Merrell TraiGlove(s).
First impressions after only a ~10km of running – these are PERFECT! They fit awesomely, are insanely light and are rugged enough so I don’t have to watch my steps too carefully. I have never used running shoes without a sock before, and could still go barefooted in these without getting a blister. Cannot say yet if this was an ultimate running shoe for me or not – I’ll know that in few weeks after I’ve used them a little bit more.
It seems there has been quite much of a hype or something around this minimalist shoe approach, mostly some nonsense that is it faster to run in such a way or not. Believe what you want to, in general there seems to be way too little of scientific studies of either. But what I want to underline from my own experience is that not pampering your legs unnecessarily can be good. Also I think there’s a long evolution behind how human feet is constructed, so that should also support the barefoot approach. I don’t race, so speed doesn’t matter. I run for my own enjoyment – and keeping myself in a shape.
I don’t run on tarmac (I hate it!), so my favourite track is gravel/sand roads or paths in varying terrain. If you have a similar place to run on – I highly recommend trying these out.
How about a coilgun?
Project idea(s) for this year. I’ve been fiddling lately a lot with electromagnetism and solenoid structures at work – but how to do something more entertaining with electromagnetism? One of the first things I can think of would be by shooting projectiles. Of course, there’s nothing new in creating a coilgun – besides the fact that I’ve never built one myself. But what I’m actually interested about in this, is to make it more efficient and not to waste any unnecessary energy to heat. Typical approach seems to be single stage coilgun where awful energy storage is converted to heat with every shooted projectile. That’s just silly.
My first approach to this topic would be multi-stage coilgun with ”energy recovery”, so energy stored to magnetic field of coil will be stored and used again in further stages. At least couple of easy ways to do this come to mind at this instant, either charge the energy straight to a capacitor through the coil (and so on…) or use the coil-stage as boost generator for next phase.
So basically increasing efficiency would mean couple of things, coils cannot be very ”thick”, because we want to keep the magnetic flux path under control and airgaps short without sacrificing too much of the mechanical simplicity. Also resistance losses is something we want to avoid (heat), so this eventually leads to figuring out the optimal capacitance and finding semiconductors to survive the quite high current pulses… More on that when I have time to do some calculations 🙂
Anyway, this leads straight to another cool side-project. When you need lots of coils, hand-winding is awful and boring task, at least I don’t like the calculation part at all – you’ll lose it at some point anyway! There’ s ofcourse option just to measure the overall length of wire and use some approximation for nominal radius of coil, but I’ve found that this is way too inaccurate for inductors. And ofcourse there can be lot of other cool uses for this toy, how about custom-made guitar pick-ups? So my ”to be” winding machine would be uc controlled dc-motor with smooth speed control, winding round calculation and some sort of automatic spreading for the available core-area. Controller part will be piece of cake, but making this suitable for different kind and sizes of coils and wires will need some thinking on the mechanical construction. Meanwhile I had to do a number of similar hand-wound coils, so I built up a little helper for the task. This was constructed in couple of hours from scrap parts and it uses old pedometer for round calculator.
Not pretty, but it works as a charm!
All cool things come in small packages!
This is already quite aged product, but as I’ve used it before on various devices and stumbled across a killer deal at ebay for 10 units, so I couldn’t resist it. Now I’m already designing a multiple new solutions to use these in. The module in question is a small ARM7 based ethernet device by Digi International – and they also have an upgraded version of this, based on ARM9. I like these a lot, it has proven to be very solid design and the supplied Net+OS very stable and quite easy to understand.
And what to do with it? For example, ethernet-enabled lightning control and movement sensing unit. Easily timed and controlled remotely. Powering can be done with POE, so it’s all standard equipment and cabling needed to use it. More on this when I’ll have time to write some more code for it.
Here’s also a pic from my test setup for outdoor led-lightning. Would be nice if it was a bit warmer in tone, and picture again makes it seem colder than it is actually. Plan is to add ~6-8 of these units in a similar fashion to light up the front yard, so it would prove enough light to see at night time but not be too bright.
Finnish rye bread [Ruisleipä ja miten se tehdään]
If you don’t know what this is, it’s a traditional dark bread here in Finland (or perhaps in all scandinavia…), made solely out of rye flour and water (and salt). No milk, no added yeast – leavening occurs through natural fermentation process. Don’t know for sure if it should be called rye bread or leaven bread, so let’s try both.
Because there was very little information present on this particular art of baking – I’ll share my experiment with this traditional bread, which I like to eat alot. I’ve never tried to do it before, as I’ve had illusion that it’s too much of a work and needs unseen university degree in magic to get it going on a modern kitchen (as I didn’t have the old traditional wooden basin, or hundreds of years old sourdough from my ancestors…) For some reason (perhaps others have been as sceptic as I was) there seems to be very little information on how the sourdough should be made from scratch. All the instructions I’ve seen rely on the fact that you’ll have saved some dough from your last patch of bread…
Sourdough:
So I couldn’t find out any exact information on how this should be done, there is lots of mixed opinions [FUD] around the internet on this. I read few posts from different internet forums, digged some information on traditional cooking book and counted 1+1 = 3. This is how the experiment turned out.
- I took a clean (washed it with boiling water) glass pint with ~2dl of boiled and cooled water.
- Crushed one finncrisp into the water (this is the magic ingredient, I don’t think it’s necessary at all, but idea of adding it was in the traditional cooking book. I’ll have try this out without the finncrisp in the future and update this if needed.)
- Added few tablespoons of rye flour and roughly one tablespoon of milk. (And for a sake of trying it out I did another identical pint without the milk to see if it would make any difference.)
Sourdough should be quite thin liquid, I added flour very cautiously. Whipped it also well as fermentation needs the air.
I left both pints in a warmish place and covered them with cloth. Whipped them over once a day, after first 24 hours, nothing had happened, but on a second day, I could see some bubbles on both pints and also they smelt a tad sour. Whipped them again, added a bit of flour and left them to ferment further. Third day made the difference. The one with milk had a lesser amount of bubbles and quite nice smell. Another was almost foamy and smelt sharper. I decided the one containing that tad of milk, would be ready and sourdough for my coming up bread. I forgot to took image of this, so no pictures of this.
The sourdough goes dough (or paste:)
And on we go after three days of eager waiting. I took roughly one litre of water (a tad above room temperature). Added the sourdough to it and about 0,5l of rye-flour, mixing and whipping it well, again coming fermentation process needs air, so this is mandatory. [And in case you had done this before already, now you just take the bit of paste you saved from last time, mix it with the water, and voila. You have sourdough. Add flour and continue.]
After this phase I had quite thin ”rye-porridge” which I left to a warmish place to ferment for a roughly 16 hours.
Sourdough worked as it should and I now had a half a bowl of bubbling porridge. Smell it, it should be nice, fresh and sour-ish. Depending on how well fermented (longer you keep it, the tougher the taste) bread you like, you can keep it in bowl for several days, just remember to add some flour once a day so the process lives on. And also remember to whip it a little while adding flour.
I decided that one day was enough for my taste (and for this test), so at this point (16hrs after mixing sourdough, water and flours) I added roughly 1kg of rye-flour and turned it into very thick brown dough. I read an recommendation that one should mix it with wooden stick or stow and add flour until the stow almost cracks in half. I think this was very correct statement and also on a sidenote: don’t put your hands in there if not necessary… It will be sticky and very messy.
Put a cloth on top of the dough it and let it be leavened for a few hours, it should roughly double in size. At least mine did 😉
Last phase is to turn the dough in to the bread. I made the ”traditional” thin disc-shaped bread out of it. Remember to save some dough for the next time so you don’t have to do the sourdough from the start again! Readily shaped discs are further leavened for couple of hours in warmish place and under a cloth. I baked the bread in middle section of oven and with 250 degrees (C) temperature – for about 30min. After you take them out of the oven, let them cool under a cloth and I strongly recommend that you cut them while they’re still a tad warm. Failure to follow this last instruction will propably mean that you’ll need a chainsaw to cut the bread :]
And then eat it! It’s just damn good, taste will beat anything you can buy from stores!
Lastly; I take no responsibility on whatever you’ll manage to create following my notes on this experiment. It is your own responsibility to know what you’re doing 🙂
I may add Finnish version of this later on.
Let there be rock (or more noise at least)!
Long time no press, I’ve been busy finding a job and again noticed that doing things is generally much more fun than documenting the doings, but here we go again.
I’ve been planning for a sort of home studio for a long time. This is what I’ve come up with during past few weeks and well, studio is a bit too hi-fi expression for the current state, but it’s a start and it works. Equipment now includes couple of nice dynamic microphones for vocals, Korg D4 multitracker, basic mixing abilities, power amplifier and close-range monitor speakers. This can now serve for singing, synth (or multitrack) backings, karaoke – whatever the need.
And it wouldn’t be mine if it wasn’t something home-made. I built the amplifier enclosure from what was once a cd-tower, so it’s recycled! Amplifier is a Tripath chip based ”Class-T” module with stated power of 2 x 100W @ 4ohms. I bought it for testing earlier this year and it surprised me with both being quite clean and quiet sound-wise but also by delivering almost the specified wattage to a load. So I made a power supply for it and put it to good use. It’s actually impressively efficient too. Amp delivers pretty much the promised wattage per channel to 4ohms with very nice THD figures and generates very little heat, shoebox has no air-holes at the moment and I can still keep the volume cranked up for several hours with no problems.
This is how it looks.
No extra bells and whistles. Switch to turn it on, power and audio in and speakers out. All you really need 🙂
Audio processing is now only done with a small Behringer mixer I purchased second hand. It still needs some nicer preamp for mics and perhaps a dsp for mix-out, more on those later when I’ll find suitable device(s) to fill the needs.
Mixer has seen it’s better days for sure, but nothing a little cleaning up wouldn’t take care of. All the channels and features work and the best part is – no noticeable humm or hiss at the output – it’s quiet!
And the microphones. Bought them based on some reviews to try them out. T-Bone MB-85Beta (Shure imitation) and Beyerdynamic Opus 29-S. I like them both for what they are, affordable dynamic microphones with solid build quality and natural sound reproduction (in my case the singer will be the main problem anyway 🙂
Last (and least) the speakers. They’re small Behringer passive close-range monitors I removed from my surround setup couple of years ago. I’ll propably upgrade these soon-ish, but as the room is quite small and they handle the available power well, result is actually quite good. Overall when considering how little money I spent on these components, this is a superb solution.
Tested this also as a karaoke setup last night, works very well indeed!
Let there be light
One of the things too long on my to-do list was some nicer night-lightning to my home and leds would be the perfect solution for that. They’re cheap and practically last forever. Like usually, I couldn’t find anything that would fit my purpose from stores, so I decided to make the led-strips myself. It’s made from triangle shaped wooden strip. Drilled the holes (by hand at this point, which is very visible :P), milled a groove for wiring in the back side and soldered the leds in place. Leds are 5mm, white, driven with constant current of up to 50mA. Lightning output was around 15000 mcd @ 20mA. Not very much in lumens, but it is enough for this sort of purpose.
And first installation of strips fitted in place, this is how it looks now in stairs. Photo is actually quite dark compared to what it is in reality. There’s well enough light now to see where you put your foot on.
