Since we moved to this house a year ago, I bought a TV for the first time in 15 years. Didn’t bring over the CRT TV (my younger colleague doesn’t even know what is a CRT TV.)

So finally bought a TV few months back and what it needs is a proper TV cabinet plus proper playback system. What’s good with video when the audio sucks?

But then I don’t want TV cabinet plus 2 speaker boxes and a subwoofer, and all the attendant wires. How about combining the speakers into the TV cabinet?

Thus I set about on my quest for a TV cabinet cum 2.1 sound system. This means… I have to scale the mountains, reach the top and consult speaker guru Gabriel… who then blessed me with a 2.1 system cum TV cabinet. And thus, the coolie starts work…

Very pleased with the sound! Good design Gabriel!

The 2.1 amp allows a lot of adjustment on the cutoff frequency and balancing both volumes, so it’s really easy to adjust and get good sound. I didn’t need to adjust much at all. Hey, even a tone deaf fella like me can do it!

All in all, this 2.1 approach can work very well.

How do you approach your TV setup? Do leave comments. Thanks!

The post Built first speaker in years… appeared first on diyparadise.

I was shocked when he sent me the photo!

Few days later, I received this Discrete R2R DAC for Raspberry Pi along with a regulated 5V @3A supply. How nice is that?

I can’t believe how Ew managed to fit everything into this small board. Hey, this is a 24 bit DAC so there are 48 resistors per channel. (No sicko enjoys soldering this bitch!). Before we even get to soldering, these resistors need to be hand matched as resistor tolerance could cause significant distortion. (No sicko enjoys matching these tiny resistors!) The heart of signal processing is handled by the huge FPGA chip.

For comparison, here’s the Final Discrete Monica I built years ago.

Zoomed in just on the main board and you can see USB input via the Amanero, of which signal is fed to a huge FPGA module (underneath this PCB) where signal processing is done. Back then I had to learn how to code in VHDL in order to program the FPGA. Hey, programming is part of my day job but the coding sequence is sequential but with VHDL/FPGA it is in parallel. This messes up our thinking.

Sequential : Wake up -> Brush teeth -> Walk the dog -> Make coffee…

Parallel : Wake up AND Brush teeth AND Walk the dog AND Make coffee…

Err, how does this happen? Well, we human beings are not great at multi-tasking (despite what the fairer sex says). But machines can accomplish this. Telling the machine how to do this… can mess up our thinking.

Look at me! I have not been the same since I programmed VHDL/FPGA!

Okay, after digital signal processing, music signal is then fed to 4 clocked buffers and the ladder R2R resistors (hand matched as well). Also, i went nuts with shunt regulated supplies on almost every stage… Also, I went nuts stripping off sleevings off the electrolytic caps (this makes a difference so much so my deaf ears could hear it).

Needless to say, building the above was a back-breaking, eye-numbing, solder fumed fest. It was anything but pleasant. I was a self flaggellating fetish back then.

Okay, enough!

And then Mr Ew comes up with this cute little package! And he programmed the FPGA as well! Damn!

Assembled below with the power supply. My itchy hands have to solder in an extra 2200uF…

Man, I was still enjoying the AD1865 Raspberry DAC when I received this new baby.

And all I could say is…. It’s GLORIOUS!

There is difference in musical presentation between the AD1865 and this Discrete puppy. I prefer this Discrete DAC as music seems to be more “alive”. It’s probably a bit more forward too, but not that irritating in-your-face sense. More forward compared to the AD1865.

It has that… je ne sais quoi… that some girls have that make you fall head over heels over them. Sure there are prettier girls. Sure there are smarter ones (or if you prefer dumber ones). Sure there are more engaging company but… She has that je ne sais quoi and you keep returning to her.

Geez…. why did I bother building DACs when we could have Mr Ew build better ones?!

The post Discrete R2R DAC for Raspberry Pi appeared first on diyparadise.

On the left is the passive preamp, sitting on top of Mr Ew’s excellent Rapsberry Pi – AD1865 DAC. On the right is Anna! An All Russian Push Pull amplifier.

The passive preamp is a restacked Intact Audio autoformer. By itself, Dave Slagle’s autoformer is already excellent, but restacked for more inductance to fit your system, that’s what a proper DIYer should do!

Note below, wired with Elma switches. I bought these years ago, back then could only afford the 12 steps… These switches are fantastic! The touch, the feel… it’s like Leica camera, you’ll understand if you are of particular vintage…

Here’s internals of Anna. It’s a heavy 2 chassis affair, done mainly because I want to hide the ugly power transformer and chokes inside. And also I don’t want anyone to accuse me of building a “lightweight” amp. Count the number of irons please…

Here’s a close-up of signal wiring. The iron arrangement… went through so many iterations before arriving at this arrangement. Mainly to minimize induced hum… Once it hums, it’s no fun… Resolving hum is just as fun as a root canal…

What is Anna? At first glance, looks like the Simple EL84 concept but instead of using differential long tailed pair as phase splitter, using iron here.

Driver stage is a plate choke loaded 6E5P. My previous experience with 6E5P wasn’t that good. Must have done something right this time… Circuitry wise, nothing special here, other than the 5 Schottkies at the cathode.

Next, it drives a center tapped choke. Yes, it’s an audio choke with its mid point tapped out. As this center tap is grounded, driving one end of the choke will induce an inverted signal at the other end. In other words… a phase splitter! It works very well here and I have no idea why we rarely see such design. So simple and elegant!

After that is our favorite SV83 in triode mode in Push pull fashion. All for a grand 4000 miliwats… Again, nothing special here…

So the magic is in the phase splitter. Push pull can be done right if you get the phase splitter right. None of that “push pull” veil here.

I would add that if you look at the music signal, every stage it sees lots of inductance.

From DAC output, it goes to an autoformer (an inductor with very high inductance ~200H)… Then to the 6E5P (high inductance on its plate 100H)… then driving another high inductance phase splitter choke (easily >100H)… then SV83… Output transformer (PP output transformers easily have >100H)…

Hmm… every stage it sees >100 Henries… Any idea what does it do?

Sorry, I’m not smart enough to tel you what it does. So I’ll just tell you what I hear here.

This is the most dynamic amplifier I have ever built. It’s only 4W but the dynamics, transients is striking. This raises a new bar to the word – realism.

Enuff said.

The post Anna – Push Pull done Right appeared first on diyparadise.

That said, the typical audiophile tends to sit his fat ass down on hours and listen to music. However, I still prefer to get out and about!

When I moved house, I took this opportunity to rebuild my music source. Few months before that, my friend Ew asked me to try out his Raspberry Pi + AD1865 NOS DAC. So it’s the right time!

The obsolete AD1865 is a true R2R DAC chip from years ago. Older audiophiles may recall seeing its presence in some Audio Note DAC. Some folks will sense an air of gravitas in this little nugget.

To save me time, Mr Ew sent me the power transformer and a simple voltage regulator as well.

Here it is, wired up.

You can read more about this fine piece of equipment on Mr Ew’s webpage.

For me this is so simple to use! Using Moode player, this is a “headless” (no display) music source with all controls from my handphone.

And I stream Spotify.

Oh no! I lost all credibility as an audiophile!

It’s okay, it’s all about the Music!

The post Rapsberry Pi + AD1865 NOS DAC music source appeared first on diyparadise.

Since we have prepared for the move, we have packed and moved some smaller items. My system has been dismantled and I even lent my amps to my friend as he tries them out.

We were supposed to move house last July but just a week before moving in, something happened and we couldn’t move house. Fast forward today, we are still in the same place.. and it seems like we are still 6 months away from ready to move in.

Anyway, life has to go on and I got the itch again.

As I have these cute little 955 acorn tubes, I just want to build something with it. So why not build a headphone amplifier? If 2 tubes are cool to look at, how about 4? How about a push pull headphone amplifier? I don’t think these are popular out there?

So I asked my friend Mr Ew to cast his magic again. He promptly wound me a permalloy 10k : 32 push pull output transformer. It comes in such a little package, I could hide them under the chassis, leaving only the tubes peeking out.

If you recall, the last amplifier I built was the 6688 headphone amplifier. It was a 2-chassis construction, with power supply in a separate chassis, connected via an umbilical cable. So why not reuse this? Since the B+ is about right too?

Since I built push pull amplifier with the Ultra Compact concept before this, why not try something different? So this time I used an input transformer as a phase splitter – Sowter 3575 ( 1:1 ct).

The construction is pretty clean this time as I managed to isolate the grounds at the input side. The input “ground” side of the Sowter is tied to its shield, and not connected to the “ground” side at the output, as shown in above schematic. Obviously, if you build such an amplifier and it hums like hell, you may need to connect both “ground” sides together.

Okay, okay, how’s the sound?

Oh my, none of that “vagueness” or “fog” of a push pull amplifier. From what I know, that could be attributed to that horrible phase splitting circuitry used.

This fell’s very quiet, very detailed, very musical.

It has none of those irritating features that drives one to stop listening

It has those attributes that make you want to listen more.

Guess what I’m saying is, I don’t hear much of the sins of omission nor addition. If this makes sense…

I’m listening via Spotify these days and even with such “non-audiophile enough resolution”, I’m perfectly happy. Yeah, it could be because of my discrete monica, or it could be that this amplifier isn’t adding hash/rubbish/junk.

We audiophiles sometimes can be quite a pain in the ass, and want to nitpick on just about anything.

If “Spotify -> discrete monica -> 955 push pull headphone amplifier -> headphones” can make one happy and concentrate on the music, what more can one ask for?

The post 955 acorn tube headphone amplifier appeared first on diyparadise.

I actually played with this little fella a longgggg time ago… via the Grounded Grid Gain Stage, back then using it as an I/V convertor for the then Monica2…  Looking back, that was likes ages ago…

Anyway, here in 2017, we have moved far ahead and the GG stage was sitting there collecting dust, so I gutted everything there, and added in some other components to finally make a headphone amplifier worthy of our time and attention.

The circuit is really simple.

Nothing special here.

You know I’m a fan of the Cree Schottkies at the tube cathodes.

You have seen parallel feed as well.

This is the first time I’m using this rubber wood chassis, as well as 2-chassis construction.

Also, first time I’m using Cinemag iron.

Cinemag CML-2394 420H (!) @20mA

Cinemag CM-13107 10k : 600/300/150/32  *50% Nickel

Rat’s nest, as usual. I have a reputation to maintain!

The 600 ohm taps go to the Output RCA while the 32 ohm taps go to the headphone jacks. Well, if I have headphones of various impedances, I’ll wire in a switch but no need here.

The tuned RC is optional. Panasonic metallized polypropylene capacitors for power supply here.

After the initial run in period, I have modified the schematic few times before arriving at current iteration. Schottkies still better than a few RC combos I tried at the cathode.

There shall be more modifications…

Okay, how’s the sound?

Marvelous! Even via audio output from my Mac, the spaciousness, the airiness… makes you want to listen and listen some more. So far don’t even detect any fatigue-ness at all.

All in, highly recommend you get the Cinemag irons. First time I’m using this irons and I believe the sonic quality is from the irons alone. The other tricks, I have played many times before.

And it’s so versatile. Could be used as a line amplifier (which I haven’t tried yet).

The post “6688 Good Feng Shui!” Headphone Amplifier appeared first on diyparadise.

But with such a huge market out there comes the conundrum – how to separate wheat from the chaff? The golds from the duds?

Here is where a curator’s weight in gold is measured!

Evil advocator of all things horn – the hornmeister himself – Gabriel told me about this manufacturer offering horn speaker kit – CNC cutting MDF pieces to be assembled by the end user. In other words, horn speakers given the Ikea treatment.

Here is another gem, this time recommended by Ew, a devil of a guy who knows way way too much about tube amps and transformers…

OK. So here is where I come in. Reading those pages, and oogling at those photos got me drooling, and so I took the next most logical step…

I bought them.

The speaker kit arrived first, all 30kg of it. Hernia alert!

Time to get horny!

A quick mock up sets the pulse racing…

And off we go!

	The first pieces are always the easiest.
	Then it gets tougher to align. Hey, my neighbours wardrobe isn’t very chic.
	Oh my, more clamps please…
	Slowly but surely, it’s getting in shape.

Almost there…

Done!

Err, from that skeleton stage to finished good, actually went through an awful lot of work. You see, I screwed up along the way (I have a knack for this) and Gabriel saved my ass (again) as he had to undo some of my mistakes before setting them right.

Thanks again bro…

The finished speakers are clad in hard wood timber strips and finished in at least 5 coats of polyurethane. The attendant driver here is a none other than our DCA4, stained to match.

Listening to it…

Hey! What’s the little tube amp there? Which brings me to the next page… [scroll down for page 2 link, dumbo]

The post the Wonderful Wacky World of taobao appeared first on diyparadise.

I guess this is what it’s called “life happens”.

Also, there is another reason for this. As your system progresses, you eventually reach a point where it’s harder to get significant improvement. I’m not so interested in “lateral forays”, more interested in “vertical improvements”, if you get what I mean.

So in other words, no improvement, no news from me.

That said, I built this amp some time in July 2015 but I had problems with it. She sings but worse than the toad in me. I spent lots of time checking before I start to suspect it is the output transformers when I then packed her up and sent to my friend to debug and rewound the output transformer.

True enough, it’s the output transformers. Unfortunately the core can’t be re-utilized, hence it’s now a C core instead. I know, the looks isn’t that coherent anymore but looking at the bright side, my wizard friend wound up an awesome pair of output trans.

With new pipes, she sang fine as a lady but… not very exciting. Yeah, I’m a greedy bastard! Is this another case of “lateral foray”?

Ahem, This is where you earn your spurs!

Buoyed by my success with Schottkies in the Wet Dream project, I had the Schottkies installed and…

Boom! Crash! Bang! OMG!!!

Through the roof Expletive Factor!

What a huge improvement!

But then why am I surprised? I was thrilled before by what this little sand device could do, so the improvement wasn’t unexpected. What’s unexpected is it is as though she went from a lithe slim lady to a kick ass MMA fighter with a bod to match.

THE BASS. THE IMPACT. THE DYNAMICS. THE PRESENCE.

When these 3 attributes improve, everything else improved by a quantum leap.

As any experienced amp builder will tell you, the biggest bang for the buck is at the front stage. So opting for the Schottkies at the 5965 cathodes make perfect sense.

I then told my friend Tim about this new girl who caught my heart, and as I was describing the sound to her, particularly the kick ass bass and gut wrenching dynamics, Tim said, “Hey, sounds like a Gina to me.”

And so Gina she is.  

All is good so far but a new problem presents itself. My favourite 5965 tube is a GE 5 star. An absolutely rock solid tube but in current iteration of Gina, the sound is now a bit too forceful and tends to be harsh at peaks.

Yeah, I like foreplay, girl, but you are too rough! Foreplay doesn’t mean a broken finger or a sprained ankle, OK? One of these days, I may end up with a torn ligament for God’s sake…

That said, Gina is back to being a lady when Telefunken 5965s are used. But what good is an amp if she only sings with rare premium tubes?

Ahem… back to what I had in mind. My original vision of Gina uses TV damper diodes to provide slow turn on and I kinda like the brightness of TV damper diodes besides the other tubes.

“Slow turn on + Foreplay = Win Win”

But the TV damper diode was taken out when I was debugging the amp when it was distorting badly.

Now that the culprit’s been identified and replaced, it’s now time to put this fella back to work.

I’m using 6AX4 here as it’s an octal tube so if I hate it, I could easily mod for other octal tube type rectifiers. The slow turn on is a bonus.

And now we have a new Gina! No more of that harshness at peaks. No more of that “I will only behave if you give me Telefunken” attitude. The heft and dynamics seemed to have reduced a little, but I’m okay with this. After all, this is the MOST dynamic sound I’m getting out of my pair of horns right now. Chew on that!

Okay, about the schematic.

Gina can be built at a budget. And I mean it.

The stars

5965s, SV83s and 6AX4s are plentiful and still cheap. Before Gina, my favourite little pentode is the EL84. After dating Gina, SV83 is my true love. There is no contest here.

The SV83 or 6P15P is operated in a triode mode. The cathode RC combo and the triode mode connection are options for mods in future. But for now, Gina is very good to me.

Don’t be fooled by the looks of the 5965. Though touted as an 12AV7 equivalent, some folks have used it in circuits calling for 12AT7 etc. From my time with this tube (since the days of the Darling amp), I find this tube to be way better than the other 12A*7 brethrens.

6AX4 is such a nice approachable fella. Big glass, uses the common octal sockets, dirt cheap, low voltage drop (~10V with Gina), pretty bright and slow turn on of about 15 seconds… What more not to like of this fella?

Power supply

Nothing special here but nowadays I stay away from electrolytics in the supply. I know the SV83 cathode electrolytic capacitor still influences the sound, so this may go one of these days but the usage of plastic caps in the power supply is recommended here. Hey, plastic works wonders on some girls right?

I didn’t specify grid stopper resistor value nor power transformer secondaries. These need to be adjusted for what you have in hand. You may not need any grid stopper resistor. My Gina needs them, as without them, there was some oscillation. Since this is a choke input supply, if you need to bump up the B+ a little, a small cap just before the first power supply choke will do.

Most amp builders will zoom in on the coupling capacitor here and tell you that you need to use boutique part here. That’s fine if that’s your preference but my Gina uses a USD2 Russian teflon capacitor. And I don’t feel inadequate in any way. And I have used various boutique caps before. But if you feel inadequate, by all means…

Gina above gives a glorious 2.3W to your speakers. Very efficient since she’s only flowing ~32mA. I recall I built a similar amp with a big honking pentode in octal sockets and even with the much higher current, it was only good for 1.5W. And not very good sound to boot.
There you have it.

Gina oh Gina!

She doesn’t need Telefunkens to shine.

So I could reserve this special tube for the special occasion.

Like when the real Gina comes knocking on my door.

Err, kicking it down is more like it. I’ll get the handcuffs ready…

The post She kicks ass! appeared first on diyparadise.

Now imagine 3!

Anyway, this article is supposedly a continuation of A Purist’ Wet Dream and The Purist’ Wet Dream Gets Wetter but I got to change to a more pedestrian title as if I were to continue along the same theme, it is actually bordering on obscenity…

From left to right, 6E5P, Sovtek 6C45Pi and Western Electric 417A.

In case you are wondering, I have been enjoying my Purist’ Wet Dream with below schematic.

Just a change of wiring to accommodate different tubes, and it’s all system go!

All 3 tubes run at 150V with 6E5P’s cathode at 3 Schottkies level while 6C45Pi and 417A sat at 2 Schottkies. Of course, as the latter 2 tubes are triodes, there is no 120 ohm resistor between plate and g2.

Here is my unscientific, humble opinion on its virtues.

So what does this tell you?

My choice of women sucks?

Who would have thought you could get 2 totally different type of sonics from one tube?

WE tubes are gifts from the gods?

At the end of the day, I don’t care. All I know is whom I want to hang out with. Sorry, girls.

The post Love Affair with Spuds – 6E5P, 6C45Pi and 417A appeared first on diyparadise.

What happened? Well, you could see I’m still alive, kicking and soldering but more than that, I have spent more than a year improving on Discreet Monica.

I know, I know, I’m a pain in the arse but with each improvement, you learn a lot more. I improved on her layout, grounding and even incorporated a FPGA for signal processing capability.

Err, in layman’s term, I had to redo the PCB layout through a few revisions (very expensive process I tell you), learn a new (to me) programming language called VHDL (VHSIC Hardware Description Language but to me it means Very Hard Darned Language), program the FPGA to replicate what I had with 14 integrated chips previously, measure and hand match the high precision resistors (a royal pain I have to tell you) etc etc…

All this effort, so that she sounds better and she’s much easier to build. She definitely sounds so much better now but unfortunately, still tedious to build. Is there more to come? Sure there is! But save that for another day.

I then wanted to build a proper All-In-One system. You see, back when we participated in the KLIAV show way back in 2008, I built an All-In-One.

Back then we have the Monica3, Maggie, output transformer coupled 6GM8 and Charlize2 built in separate chassis and linked via interconnect cables, like a typical separate system.

Once built into a single chassis, the sonics gained a quantum leap!

Why so you ask? It could be lack of RCA interconnections, much shorter signal path and more crucially, the much much shorter return path (also known as GROUND) path between components. Simply put, the electrons travel in a much much shorter loop and they are happier :). And my electronics background tell me that the happier the electrons, the better the sound! And so it proved.

That was then, so I had to build something better today. Since we are going on a purist’ path here, might as well go all the way with just a single gain stage throughout the signal chain. And nothing is simpler than a one-tuber aka spud amp.

Over the years, have always wanted to build a spud and back then the popular tubes were 417, 5842 as well as 6C45. There are others but those are usually 2 stages in an envelope. I’m being purist here. I want ONE and ONE only.

The last few years, another tube gained popularity and it’s a Ruskie 6E5P tetrode. I learned a lot about this tube thanks to the fine work done by Bartola Valves as well as Romy the Cat.

Now this little fella is a like a super tube. Specs wise, everything rocks! So much so that I just have to build it!

Also, over the years, I have heard a lot about the parallel feed scheme. I’m not sure how many commercial amps out there have such a scheme. Just shows us hard core DIYers are more cutting edge than mainstream. Ha! So this is a fantastic vehicle to put in everything together.

And so, we have… A Purist’ Wet Dream.

The initial idea was to build this to be mounted on to a wall but since I’m a such a pain the arse, I just can not build a simple amplifier. So 2 power transformers, 2 power supply chokes, 2 plate chokes, 2 parallel feed output transformers and 4 beer cans oil capacitors later… this whole contraption is just too heavy to be mounted on the wall. So now it has legs and it’s going somewhere!

Input takes USB from your Music Machine be it Windoze or Mac and
Output goes to your speakers via the binding post

USB Input – Discreet Monica – modified Intact Audio Autoformer Volume Control – triode-wired 6E5P Magnequest Iron Parallel Feed Output – Speakers!

All in all, there is only ONE gain stage throughout.

Want to know more about this Purist’ Wet Dream? Stay tuned for the next article.

The post A Purist’ Wet Dream appeared first on diyparadise.