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.

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.

I’m in sonic heaven with my new amp now!

Wait!

I don’t know about you but I’m certainly not like this. I know most folks would be satisfied with their tube amp after the first build but not me. I’m not like the 95% here. I’m an Alpha Diyer, I’m the top dog 5%.

But first of all, forgive me for I’m an uncouth fella. No, I don’t spout Byron, I don’t drink red wine or whatever the fancies that elitism hobbyists like audiophiles like to engage in. Instead, let me confess. I’m a pot bellied, hair receding, foul mouthed dude. Led Zep is my type of music and I love my brew of common man stout. In this regard, I’m the 95% Sir. Why heck, I even pick my nose in public. [*facepalm*]

An Alpha Diyer is always exploring ways to improve on his system. So much so that in the back of his mind, a trip to a hardware store, departmental store, IKEA etc is always an audio excursion.

And so, I’ll illustrate what an Alpha Diyer will do once he built his amp. And it’s certainly no lounging around.

But first of all, let me introduce you to the Expletive Factor. You know the reaction when the sound improved by so much that you JUMP (standing up doesn’t count) up from your seat and start spouting swear words, expletives… so bad that I can’t even write them here? (I still want this site to be family friendly, okay?)

What we are looking for is BIG XXXXing improvement in sonics. Not subtle changes that you have to A-B like hell, until your face looks like you are constipating to hear the difference. Imagine an improvement so great that you leap out off your listening chair and spew the most colourful language known to mankind!

Better still, if you swear words that aren’t in your daily vocabulary. That can only mean the sonic improvement is HUGE!

Okay, here’s what an Alpha Diyer will start off with.

Build the best power supply you have heard — Very High Expletive Factor
I mean it. The best power supply you have built, heard and optimized. Not because some dude (like me) said so. We all value different things in audio so it’s best to go back to your experience.

For me, I like choke input, lots of chokes, not too high capacitance and 100 Hz hum reduction via tuned choke.

I arrived at this supply after years of building tube amps. The 47uF caps are Solen metalized polypropylenes but the 20uFs are oil capacitors. Oh yes, the supply is HUGE, HEAVY and screams ALPHA all around. Notice there’s no electrolytics anywhere.

Move beyond simple self bias stage — Very High Expletive Factor
Initially I had a simple self bias stage at the cathode. However, you can’t move earth if you stop here. You got to experiment.

On another amp I built years ago, I used LED at the cathode and didn’t quite like the sound. The bass got too boomy. Looking back, it could be the speakers’ issue rather than the amp.

Anyway, for this mod, I’m using Cree Schottky diodes here, as illustrated by Maxamillion on Audio Asylum. 3 diodes gave me the cathode bias I need.

Optimize parafeed — High Expletive Factor
In my first build, I was using a 5k:8 parallel feed output transformer from Magnequest. The 4.7uF parafeed cap was optimized for bass response. A huge improvement over the initial 3.3uF.

As I was using 16 ohm speakers and I need a bit more gain from the tube, so I went for 3k:16 ohm trans also from Magnequest. Now the 4.7uF cap just doesn’t give me enough impact.

I don’t have any 6.8uF or larger caps. The next larger I have is a GE 17.5uF oiler so this went in and the bass impact came back after some running in.

Less Gain Stages — High Expletive Factor
Every gain stage somehow changes the signal. So if you could get by with less, do it! The 6E5P could actually put out 1-2W of power but as my DAC only outputs ~2V, the output power delivered to the speakers is now only ~0.3W.

By right, I should put in another gain stage to squeeze out more power from the 6E5P but since my speakers don’t need much power, I could get away with this. So what’s wrong with 0.3W?

Optimize signal/return path — High Expletive Factor
This makes hell lotta difference! If you ever worked on PCB layouts on high speed digital designs, the phrases “short signal path”, “return path”, “ground plane” etc all carry significant meaning to you. I’m not smart so I suffered and learned the hard way before I learned all this and I’m still learning.

Okay, that’s all I have done so far. In the spirit of this article, I’m not done yet! To be tried in the near future…

WE coupling

Try other spud tubes
Top of my head, 417, 5842, 6C45pi, 7788… Actually I have all these tubes in hand…

The post The Purist’ Wet Dream Gets Wetter appeared first on diyparadise.

Charles Altman from Altman Micro Machines explains what is more important for digital audio is the sampling rate of our media rather than number of bits. Have a read on his page. Don’t worry, I’ll wait.

Thanks for coming back.

So the higher the sampling rate, the better it is for our “signal reconstruction”. Hey, that’s what a DAC does basically.

So how about some real life example? How does Monica’s TDA1545A cope with higher sampled material.

And thus, I began my experiment.

But I hit a snag. Apparently, high resolution test tones are not easily available. 44.1/16 versions abound but not higher rez. Fortunately, you could create your own high rez wave files by using Linear Tech’s excellent LTSpice.

I also have a bigger problem in that I don’t have a media capable of high resolution. For the sake of you dear readers, I have to spend money… [another excuse to buy!] and I bought a John Kenny modified I2S Hiface module.

The signal path is now… Mac Mini -> jkenny I2S Hiface -> I2S Monica. Software is Channel D’s Pure Music Player and music library is via iTunes.

Oh yeah, did I mention I built a new I2S Monica as well?

Did I mention I had to haul the whole Mac Mini setup to the listening hall?

All this done [phew!], began feeding test tones. Please note that these test tones are created using the described sampling frequency. Note that no software/hardware upsamping nor over sampling is performed at all.

44.1kHz sampled

1kHz sine wave

10kHz sine wave.

16kHz sine wave

As you could see above, 10kHz above, the DAC is struggling to reconstruct the sine waves.

96kHz sampled

1kHz sine wave

10kHz sine wave.

16kHz sine wave

10kHz is still decent but 16kHz is a stretch…

192kHz sampled

1kHz sine wave

10kHz sine wave.

16kHz sine wave

Wow! 16kHz is no problem here!

So what does all this tell me?

The problem of digital audio is not in the equipment. It is in the material. We just need higher sampled data to begin with.

If fed high resolution material, our “vintage” DAC chip is far from an old clunker. It is still capable of reconstructing the signals properly.

In other words, Old is Gold.  ha ha!

The post Old but Gold appeared first on diyparadise.

Simple EL84 poweramp/integrated

I’m a simpleton when it comes to names.

The simple preamp using 5687 was named “Simple 5687”.

Now that we have a poweramp/integrated using EL84, it’s going to be called… “Simple EL84”.

I’m going to divert from conventions here. MY conventions.

This amp is push pull, not single ended. I like single ended better but it gets freaking expensive if you need more power. Push pulls, being more efficient, can do a hell lot more power. Besides, not everyone would want huge, coffin-like high sensitivity speakers in their living room right?

Also, using capacitor input power supply here, not choke input.

Using solid state diodes! (shrugs!) No tube rectifier here.

Musicians look at music scores and spend hours talking about it. DIYer wannabes spend hours looking at a circuit and days talking about it.

But this amp is more than your conventional push pull amps. You see, conventional push pull amps consist of at least 3 stages. Driver, phase splitter and power stages. This bugger here, has only 2 stages. Phase splitter and power stages are combined. The idea isn’t new (what else is under the sun?) and you can read about here… .

Notice some novelty here?

First of all, only one coupling cap per channel! Push pulls usually require a lot more! At least 4 pieces. 6 pieces are common too. Real pain if you want to upgrade all of them to Jensen paper in oils… But as there’s only 2 caps here, you can afford to splurge!

What else? No feedback! Usually push pull amps use feedback but none here. Actually there is some local feedback as there’s no cathode bypass caps but there’s definitely no global feedback here.

And? Simplicity! Looking at the schematics, it looks just “one tube extra” compared to 2-stages single ended designs. Very easy heh?

Lastly. If you believe all the audio diatribe about evil electrolytic caps. Look at the circuit again. No electrolytics in the signal path! (actually there is in the power supply but give me some leeway okay?)

The driver stage is sooooo simple that you can’t afford to take out any part! It’s simple as it is. Since the EL84 in this configuration needs less than 15V to swing to full power, if your source signal leve is 2V, this means you only need a gain of < 8x to drive it to full power. Gain of 8? You don’t need

expensive 12AX7 (gain of 100)

slightly cheaper but still damn expensive 12AU7. (gain of 40+)

move over, 6SN7, 6SL7…
In fact, you could use almost any tube! The design above shows JJ’s ECC99 as I have never used this tube but have heard lots of good things about it.

WAIT A MINUTE!

I have already built the Simple 5687 preamp. If you said that any tube can drive the EL84 to full power, can I just use it?

Of course! And this is the beauty of this design! If you have already built the Simple 5687, all you need to build for the power amp is this!

Or you could combine the 5687 driver stage and the EL84 power stage to make your own integrated amp. Cool huh? Life is so much fun when we have so many choices! You could build this with all modern tubes! JJ ECC99 driving JJ EL84. Or all NOS tubes! NOS 5687 driving NOS EL84.

But NOS EL84 aren’t cheap…

This is where DIY Paradise comes to your rescue again! EL84 is also known as 6BQ5. WE DON’T HAVE TO USE 6BQ5. We could use the 8V version, which is 8BQ5! (As I write this, some folks are going to curse me. The price of 8BQ5 is going up! Thanks to fellows like me…)The only difference being this guy needs 8V heaters as opposed to 6BQ5’s 6V heater. If you are going to DIY this amp, you have the flexibility of customizing your power transformer. So you could specify 8V heaters. No problem at all. Non-DIYers are tied by the available heater taps on their amps… DO NOT BE HANDICAPPED, fellow DIYers. Break free!

Does it end here? Not yet!

The circuit above is wired for ultra linear configuration. (~10W)

If you tie g2 to B+, you have pentode configuration. (~15W)

If you tie g2 to plate, you have triode configuration. (~5W)

In other words, once you built this amp, you can really really really anal, and wire a switch to switch between different modes. How’s this for 3 kind of sound in one package?

Oh well, and so I built the above amp with JJ ECC99 and NOS 8BQ5. Proceed to “Building the Simple EL84”.

The post Simple EL84 integrated/poweramp appeared first on diyparadise.