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: Way out
Your way out to various sites in my interests
Jolla: Initial thoughts
So I did something I wouldn’t usually do. I bought an expensive smartphone – which I supposed would be quite unfinished and might even remain as marginal toy without ever gaining actual user-base or larger software support… I must be out of my mind? See Jolla official site for what it is!
The why part is simple. I’ve used IOS on Ipad for long time and I like it for that. Still with the polished user experience and very good selection of applications, I’m not sure I’d need it on my phone. There just is nothing in there that says I must have it with me everywhere. It’s well optimized and it has all the apps one can need (and more) – but still… Then there’s Android, I’ve used Sony Xperia Active for a year now – without rooting it – and outcome is that it was most likely the first and last Android phone for me. Mainly because of the bugs in the OS that no one will ever address and fix. Also with non-rooted phone, I’ve run low on ”system” flash, so I cannot update my apps anymore and also cannot move most of them (bundled software) to external SD card or even remove the parts I don’t need to make more room… Rooting would be the key and I guess I’ll try it now as I have new phone for everyday use.
Last option was a Windows phone. I’ve tried WP7 and Wp7.5 and even WP8 at the local shop, initially it seemed ok, but after trying it for longer term, it became clear that I don’t want that either.
So to get something that could offer something new (even new bugs!) I pre-ordered Jolla last spring. I got it a bit over two weeks ago, so I’ts been on daily use since then and I’ve discovered some bugs and annoyances, enough to judge that I can use this.
First up, everything just worked from the box. Jolla store seemed busy and some apps didn’t install on the first try, but eventually I got all the offered software pieces in place. It was more finished product than what I had hoped for, so this was very positive experience. OS is very smooth to use with the swipe gestures – I like it a lot and have already been trying to use my other devices with the gestures… Add a voice control and this will be perfect!
For Andoid software support they have chosen a very buggy store (Yandex), so getting that up and running required PC (phone browser most likely would’ve worked just fine too) to set up the account. Not big deal, took a while to figure out the reason why captchas won’t work in the account creation. Based on comments I’ve seen it is because the store application has trouble detecting connections. Jollas framework seems to work in that sense, so any other android app that required internet connection seemed to work. Luckily there are other markets that you can use, even google play can be hacked to work. I’ve settled now with 1 Mobile Market, which fulfills my app needs nicely.
Basic set of apps are available from Jolla, rest of the needed ones can be downloaded from Android market. The framework is a bit buggy, I’ve managed to crash it couple of times and it seems it’s not clearly repeatable. But mainly it works. If I’d need constantly some andoid apps this would perhaps annoy me more, now it just means that some software doesn’t always load. I’ve so far used Skype, Facebook, Opera browsers, Spotify and Endomondo from andoid apps. Also some other, but those are the ones I’ve used and need most frequently. Endomondo was the most critical for me as it’s my cyclometer nowadays.
Camera is very basic 8MP mobile kit. The camera software will need some care and optics seem to be perhaps cheaper than usual. In use this seems like the early generation digital cameras, white balance handling is very poor and lights blind the camera easily. But I didn’t buy this for camera. It’s ok for occasional shots and documentation – which covers my needs from cellphone camera. Tried shooting some live performance and audio doesn’t convince either. There is way too much of audible compression artifacts in the recording – sounded pretty much same than my android phone, but this can withstand higher SPL without distorting.
I made a sample gallery to my Picasa albums, see for yourself. It’s decent mobile camera at best. They claimed that on last software update there was some updates to camera software on low light conditions, I haven’t tried it yet to see if there is any difference.
There are some annoyances also. Clipboard doesn’t work from the browser and I think this is major – I cannot select text from the web page to use it elsewhere (say phone number from web page or text paste from browser to SMS) and that is very silly. I really hope they’ll address this soon. Android apps have working clipboard, but that is not shared with Jolla native apps. There were some other issues – including exchange sync with non-trusted certificate – but most of them seem to be solved with the two software updates they’ve rolled out this year.
There’s also been some news about the battery performance it seems that in airplane mode the phone drains battery very fast compared to another phones on the market. I haven’t tried it yet but in a daily use, it’s about the same level than what I got from my android phone. Proven this has much better and larger display I think it’s on very acceptable level. In heavy use it will be charge daily, but on weekend I can go two days on a charge.
Other half concept is very interesting. At the moment the customization options seem a bit limited, but once the OS framework is more complete (more options to tune) and as there is also electrical bus (I2C) available to back cover so all kinds of functionality can be implemented in it… When I just have more free time!
Overall this is a now a working smartphone with most needed features in place (browser, email, sms, and a phone!). It does not give you a perfect user experience (yet, I doubt any of the platforms do) app support is a bit limited but with help of the android framework, I think most required apps can be installed. And there are and will be some bugs and non-working software pieces at the moment. So if you want everything working right now, do not buy your Jolla yet [and for that matter, I could suggest staying away from any smartphone!]. Anyway even with the small flaws this shows a great potential. With some small feature implementations and bug fixes (which both seem to arrive at very quick pace!) and more added native software, this could be a great challenger in the market. I hope the company, phone and the OS will survive as there is a real need for good alternative mobile OS, this could very well be it.
Some Jolla specific links:
Official site
Collaboration platform
Sailfish OS
Jolla tides
Jolla users
Native software for Sailfish:
Jollasuomi – Finnish forum
WLAN Hotspot UI for Jolla – Much requested UI for wifi hotspot. Very nice work!
WLAN Hotspot UI for Jolla #2 – Another one with perhaps more complete feature set by . Perfect!
Cutespotify – Native spotify client for SailfishOS and Ubuntu touch. Good stuff keeps on coming!
Updated for software links…
The day they broke imdb
I’m a regular user of imdb, when I notice an interesting actor or when I ponder if I should watch some film or not, I usually dig it up from IMDB. Now this actual incident is not very recent, but it has bugged me more than anything in a little while. Now in my opinion movies should, by default, be listed in their original title – and it has been like this for ages. During this autumn someone has had a brilliant idea to bring up the translated titles by default from imdb.
Let’s give an example, I was looking for some actor and his particular listing of movies looks like this:
This poses many problems. The biggest problem is that someone assumes all connections from Finland should want titles in Finnish! Next thing is, that if you buy a film ”Paavo Pesusieni” (or whatever translated animation / cartoon), there’s most likely a Finnish voice in place of this (even though, dvd’s propably always have the original soundtrack) and therefore this is error in listing. And it looks ugly too! Nevertheless, I found this very annoying, so annoying that I’ll write about it. What makes it worse, is that this usually brings up translations I’ve never heard of before! I mean, they could’ve put the site to listen for user-agents preference on language instead of some geo-ip policy, it’s not so hard?
Then again, I clearly wasn’t only one loosing hair over this and there is a solution to this problem, you can use http://akas.imdb.com/ and get the titles as they used to be. Which is my primary movie-source now 🙂