Though I’m a single full range driver fan, I’m okay with the other camp of using active crossover and multi way speaker drivers.  Different path, same goal.

With single driver, we have simplicity.

With multi drivers, we seek control.

Most likely you’ll be using tweeters, mids and woofers from different manufacturers with different specifications, particularly sensitivity. And the key to integrating all these drivers singing is a crossover system.

Active crossovers like the Behringer DCX2496 does this particularly well. With a touch of a few buttons, you could choose your crossover type, slope and equalize the gain of your filters to match the drivers you are using. Great stuff indeed!

But what if you are a fussy pot who prefers everything done in the analog domain?

Or perhaps you need larger gain than available from your active crossover?

Enter Beyonce!

Though Beyonce is designed as a stereo preamp, Beyonce2 controls volume of 3 stereo sets, albeit all with same gain. So some engineering hard work is required to modify her to have 3 stereo sets of independent gain.

Here’s an implementation.

Some hardware modification and A LOT of engineering on the software later, we have a fully functional 6 channel (3 stereo sets) preamp with digital gain control and 3 sets of gain.

For simplicity, the 3 sets are named A, B and C. Of course, if you desire more than this, let me know!

Integrating the offset control into the Apple remote control is quite a task. To access the Offset Menu, press >>|.

Here’s the controls within the Offset Menu. As you can see here, gain and attenuation for each stereo set could be configured for -12dB to +12dB. As we only have 2 characters to display this info, 10, 11 and 12 are displayed as A, B and C.

Upon power up, we start off with Mute which is -96dB. If you press “+” to increase volume, master volume starts at -36dB.

So if

A is set to n3, B set to P5 and C set to nA,

this means

A is programmed for -39dB, B is -31dB and C is set to -46dB.

Every incremental step corresponds to 1dB in gain/attenuation. If you desire greater control than this, let me know. The chip could be configured for 0.5dB increment. There’ll be more programming of course.

Note that you could also save your settings by accessing menu SS (for Save). Settings will be saved via the onboard EEPROM of the micro-controller. 88 will be displayed and blink twice during writing.

Upon power up, you have this new setting! Until the next time you rewrite it, of course.

So now, do you fancy Beyonce? How about 3 of her loveliness?

The post Beyonce in a Threesome? appeared first on diyparadise.

Before I studied the art, a punch to me was just like a punch, a kick just like a kick.
After I learned the art, a punch was no longer a punch, a kick no longer a kick.
Now that I’ve understood the art, a punch is just like a punch, a kick just like a kick.

When you first approached diy audio, a resistor, a capacitor is just another
component. Then after you have read so much on the Net, tried some in your
circuitry, a resistor/capacitor is more than just that. There’s carbon/metal/tantalum film resistors, constructed foil type, wirewound, non-inductive and so on… For caps, you worry about its dielectric material. Is it teflon? Paper in oil? Polypropylene?…

But when you start accepting that a resistor is just a resistor and a capacitor is just a capacitor; when you begin to look beyond its details and could now see the big picture, that’s when you reach “a higher level”.

You should have enough opinion and experience to know where in the circuit to use what. By that time, you should be exploring the circuitry in greater detail than fussing about the components.

Sure, sound is the sum of every component in the circuitry but to be able to
transcend just looking at components, and going a deeper level, that’s when you have matured as a diyer.

It’s like when you first started diy audio, you are told tube amps sound better than solid state but now you should be able to see that tubes or ss, as long as the circuitry is good, the implementation takes into account
electrical/psychoacoustics consideration, both technologies are capable of great
sound.

Remember the fuss started by 47 Labs with its Gaincard amplifier? Many ditched their tube amps for it, just like we lost count the number of folks who prefer Charlize over their amps. (BTW, count how many audio companies offering gainclones these days…)

Who would have thought that LDR volume controls could trounce Transformer Volume Controls in the region of dynamics, transparency and immediacy? Virtues which TVCs should reign supreme?

Why heck who would have believed even a volume control chip implemented ala Beyonce could already outperform TVCs?

Who would have believed a 10W Class T Charlize could out-sung tube amps whose filaments already consume more than 10W?!

So stop carrying your hifi myths. Unlearn what the industry tells you and just rely on your ears.

So tubes or no tubes, LDR or TVC, whichever the route, if it sounds better, than that’s all that matters!

—————————————————————————–

On the other hand, what Bruce Lee is also telling us is that kicks and punches are just one of the elements of his art. There’s more to it than just kicks and punches.

Equally, in audio, there’s more to it than just tubes vs ss in amplifiers. There’s the preamp, the colume control, the DAC, the transport, or the phono stage, the turntable.. Moving downstream, speakers and not forgetting all the cables linking everything together, and the room where the system sits, and our state of mind…

Which means to say, if you focus only one element, say amps, it’s like just
focussing on kicks in martial arts. There will be a glass ceiling on how far you can go.

I’ve come across many diyers who only focus on ONE element of their system but do not go about holistically, to improve the sonics of every gear in his system.

It’s like an amp designer who tells the world he has built the best tube amp in the world but then when you look at the speakers and dac he’s using, you wonder how can he design such an amp…

Imagine this guy who claims he has built the amp to rival the Audio Note Ongaku but in his system he uses Bose mini sats and a $90 dvd player.

I could hear you say “He can’t be serious!” from here!

So what’s the point I want to make here?

Don’t go fussing too much about your audio components.

Approach sonic improvement like the Japanes – kaizen approach which is a
continuous improvement approach by studying every part of the system, then once
done, go through the whole system again.

So say you start with your amp. After improving your amp, focus on your DAC, then your transport, then your speakers etc. Then start all over again from your amp. Each time you improve something, it reveals the pluses and minuses of your system. Flaws obscured by your system’s lower resolution that were not heard before could be highlighted now and thus needs fixing. That piercing highs you heard may not be because of your tweeter, but your amplifier oscillating like crazy.

So you go round and round, in a cycle, improving each element of your system. And not just focus on just kicks.

System building is a dynamic process and continuous improvement is never static. It should be ongoing, it should be enjoyable and you should be having fun!

The post Bruce Lee and Our DIY Audio Journey appeared first on diyparadise.

Have no fret as here we present you, our Beautiful Eva.

There you go girl, Beautiful Eva!

The post Beautiful Eva appeared first on diyparadise.

Raise your hand if you are a fan of Beyonce. If not yet, that’s because you haven’t heard her sing yet!   This applies to our Beyonce too!

In a previous article, I wrote about the various forays into volume controls. Well, it wasn’t just those few mentioned. Over the years, have tried out Alps pots, DACT (not in my system though), Transformer Volume Controls, Autoformer Volume Controls, even nickel cores blah blah blah…

Each has its strengths, each has its magic, and each has its pitfalls. Hey, I know if I keep on fussing about volume controls, then life would be at a standstill. There’s just too much to play out there!

But I can settle on one now. Hey, which guy wouldn’t want to settle down with Beyonce?

Well, Beyonce is based on Texas Instruments’ PGA2311, described as a “Stereo Audio Volume Control”. It’s digitally controlled, that’s why we have that big bad micro-controller onboard. In future, I’ll be teaching this big bad fella more tricks. Yeah, give you more features!   This chip is capable of gain and attenuation in the range of +31.5dB to -95.5dB. However, Beyonce is only programmed from -35dB to +31dB so a display of “00” means Mute (or -95dB), “01” means -35dB, “02” for -34dB and so on, in steps of 1dB. If for some reason, you have a need for -63.5dB or -88.5dB or some numbers outside this range, or you prefer steps of 0.5dB, let me know. I’ll happily customize for you and make your pay!   Input impedance is 10kOhm. At the moment, upon powering up, she starts off with Mute. If need to, I could revise the program to remember the last setting. Some day…   Oh yeah, PCB is using black solder mask (Hey, black is the new Gold) and pads are silver plated. Still lead free and very easy to solder.   Power wise, there are onboard +5/-5VDC voltage regulators so you need to provide her >+7/-7VDC. Don’t go above 20VDC though as even though she’s a hot girl, you don’t want her to get too hot until you can’t handle her.   She’s supplied as an assembled/tested PCB module for now. FOR NOW.   Along with the remote control (which could be used for another -future- product), and the Molex connectors for the power supply. If you need the molex connectors for the signal wiring too, just ask for it.

Input/Output as well as Power Supply connections are labeled onboard BUT do confirm your DC voltages are correct before you plug her in. I didn’t install any protection diodes onboard so please please be careful OK?

Okay, that’s all for now. Got to go shake my booty with Beyonce!

The post Beyonce! Beyonce! appeared first on diyparadise.

And we have been working hard to put her into production but encountered many problems along the way. Along the way, we have folks, lots of i’ll emphasize here, asking when will we ever see the light of the day on our new volume control. Even more and more folks are asking on the forum.

So it’s only fair I’ll spill the beans here.

We found the Light Dependent Resistor (LDR) solution to be much much better than ALL passive preamps we could lay our hands on. This includes transformer volume control, autoformer volume control, shunt/series resistive stepped attenuators, marque volume pots like Black Beauty…

And the list of TVCs include those amorphous types, nickels, C-core blah blah blah. In short, the LDR triumps over all.

But building it isn’t easy. LDRs aren’t manufactured to tight specs (despite what the manufacturer tells you). Also, some exhibit drift over a period of time. All in all, it’s easy to build, but difficult to get it balanced between channels. Otherwise you’ll most likely get channel imbalance.

Our production unit is so close, yet so far to fruition. Plagued by the said channel imbalance problem! We are still working on this. In the meantime, made progress on other areas. Thought i’ll share with you here.

Err, you could build your own ldr volume control. It isn’t that difficult at all.

Make your own LDR volume control

That’s how easy the schematic is! The 24-100 ohm (1/4W will do) is meant to limit the current flowing into the LED. The 250kohm linear pot controls the current flowing into each side. You, of course, have to align the LDR/LED nicely…

In fact, a trip down to an electronic parts store like RadioShack and you have everything you need. Any 5V supply will do. I use a switching supply which is a bit noisy but doesn’t affect the operation here as the power supply circuitry is isolated from the LDR side.

An integrated chip solution
Also, I have worked on another volume control application. This is using Texas Instrument’s PGA2311 – a… volume control chip.

The 2 hefty trans is for the +5/-5V supplies. Shown here is the underside of the PCB where the LED display shows at which volume setting you are on. Also, the IR receiver sits just above the LED display. Oh yes! This means it has remote control features as well.

All in all, this TI solution works pretty good. Sound wise already kicks the ass of many volume controls out there. Even BETTER some TVCs.

Hey hey hey, wait a minute. Such simple solutions but beat the living daylights out of those expensive TVCs? No, I’m not on drugs. I believe the key reason why these volume controls sound better is not so much on its design but more on its absence of the physical switch. No switch, thus no contact problems. No contact problems, no degradation of signals and thus no degradation of sonics.

Comparing to the rest of the volume control applications, both applications above reign in the region of dynamics and especially dynamics. Ever hear folks complain that passive pres sound wonderful but lacking in dynamics? Well siree, here’s loadsa dynamics for you!

Please be patient. We are still working on our LDR solution. It has remote control and LED display as well. We just need to fix the channel mismatch problem.

Or, you could just rig up one yourself. Minus remote features of course.

Update on 2nd Dec ’08.
I forgot to link to the excellent (and very long) thread on diyaudio about the “Lightspeed Attenuator”.

After more hours of running, I’m totally surprised by PGA2311. Sounds VERY GOOD now!

The post all about volume control… appeared first on diyparadise.

Stepped Attenuators are Sooooo Muchhhhhh Funnnnn

Oh yeah… Thanks to the ultra-resourceful guys from www.my3c.net, now you could get a stepped attenuator yourself for dirt cheap! And they come with Dale RN60D 1% precision resistors as well… which if you were to purchase these resistors separately, would cost more than what you paid for this kit. Unbelievable!

To top it off, there’s even a website showing you, step-by-step, how to build it up. This beats some kit suppliers asking for USD20 for their manuals. Bah! By the way, link to purchasing the attenuator is somewhere near the bottom of that page.

Unfortunately, when I bought their kit, they only had the 10kohm version then. They now have 100kohm version as well, which is great for tube gear! But I’m left with my own 10kohm version, so I bought some metal film resistors (92 pieces of them to be exact) and proceeded to build my own 100kohm stepped, albeit without the “glamour” of boutique Dale resistors.

And so I bought the resistors. But didn’t touch them till a week later. How long a week is when you are tied up with less important issues like your day job… Then Diyer Steven paid a visit. When I was relating my “grand” plans with my stepped attenuator (as usual, so full of myself), Steven quickly told me that he has a lot of problem fitting his attenuator into his chassis. You see, if you built up the attenuator as described on the website, you’ll end up with a stack which is 6cm in height, which in most cases, most probably can’t fit into your existing preamp chassis. Imagine after toiling for 3 hours soldering this behemonth and you can’t fit it into your chassis?

Thanks to Steven, now armed with the benefit of hindsight, I had to build the attenuator in a different way. If you scroll down the last JPEG on the excellent tutorial page, you’ll see there are a few other options suggested. Of note, is the last option, which is the most compact in size and construction. Hey hey hey! This is it!

And this is how your wire it up.

Please note that Left and Right channels are split at the center. “In” is via the center 2 most terminals, followed by “Out” and GND at the outer ends. You will have to use those thick copper wires as ground.

This method of construction is much simpler and you only need to work with 2 thick copper wires instead of 4. Plus, mistakes are easier to rectify. After building mine, one of the position was quiet. I checked and found that I got a wrong resistor there. Hmm… To correct it, just undo the solder connection and redo it. But if you followed the “stacked-up” construction as encouraged by the tutorial page, you’ll be stuck with desoldering lots of resistors!

There’s another plus point with this construction. You can be really really cheeky. Ever wondered how does Kiwame, Riken, tantalum, Holco blah blah blah resistors sound in your setup? Easy! Unless you have many amps with power ranging from 1W to 200W, most likely you will only use a couple of settings on your attenuator. The rest of the resistors are just… spectators. Yes! Use them! Say you find yourself using position #12 most of the time, which is, say, -24dB. Now you could go funky by removing all those resistors on positions #13 till say #16 and replacing them with equivalent -24dB resistor sets of Kiwame, Riken, tantalum and Holco. This way, it’s soooooo easy to compare their sound. Does this sound like a sound idea? It sure beats soldering/desoldering all the time!

If your purist friend balks at the idea, saying Kiwame has to go through “less of the switch” compared to Holco, well, you can always solder the resistors around in different locations. Or perhaps even mixing them (Dale with Riken? Kiwame with Holco?) for a “rojak” (mixed-up) sound? Then you can tell your friend, “I blended and mixed up their signature for a perfect blend that’s unique to my taste”. Hmm… Sounds like rolling your own cigar…

Okay, I have talked too much. I’ve built mine. It’s time you build YOURS.

The post Part Recommendation: Build your own Stepped Attenuator appeared first on diyparadise.

Pots for Penny Pinchers!

How to make your own stepped attenuator for… < RM10, < RM30…

Alright, I have always been a cheapie at heart and here is another nice project.

I’m not actually fond of resistive volume control as having listened to an amp WITHOUT any volume pot (straight from CD), it sounded so much better. There seems to be more air and no loss of dynamics. But we live in a real world, so until one day I could splurge on those nice transformer volume controls, stepped attenuators will have to do.

First of all, you need to get a rotary switch. It would be great if you can find something that does stereo and more than 20 positions. If you find something like that, great! If not, 11 position will do as well and I recommend the 11 position rotary switch made by Alpha that retails at only RM2.50. Cheap! (they look suspiciously like those USD40 Sweet Whispers from Bottle Head…)

Better still, you can be more macho and buy the ceramic rotary switch from www.kwtubes.com. Gintaras is a great guy to deal with! This rotary switch has 4 ceramic poles and the connections are all silver plated. Unfortunately, you need to drink lots of Tongkat Ali to turn this guy. Very tough! The tiny control knob that comes with it doesn’t help at all. In the end, I had to file off the peaks on the detent wheel and remove one of the springs. This helps A LOT. Access to a grinder is mandatory as filing manually will make MANY unhappy afternoons. This 11-position switch only cost me RM20, so you need to do some work. What’s a little work for us macho men??!!

And then, you can always go to Farnell or RS Components but do expect to pay a premium. Other options for rotary switch would be to salvage them from junk equipment. Oscilloscopes and the like always have some little treasures. I salvaged 3 pieces of nice Swiss-made Elma hermetically sealed 11-position rotary switch from some junk equipment before. Nice… Otherwise, you would need to spend big bucks on the likes of Elma, Goldpoint, DACT, Seiden… Ouch!

Wait a minute! Is 11-position enough? How comes those nice expensive switches all have 23 positions or more? Truth be told, you get what you pay for. Second thing is, it is my experience that you rarely use all 23 positions. You almost always use only half of them, so why not find out which half is useful then just use them! The 23 position is made for “general use”, and attenuation can go well down to say, -60dB. It really depends on your system. In mine, I find that -30dB is more than good enough. Remember! You are buidling this for YOUR system and not for “general usage”. You need to do your homework here!

Now comes to the second ingredient: resistors. Preferably metal film for lower noise and better frequency extension but I’m not going to tell you which to choose. If your favourite is Holco, Caddock, Vishay, Shinkoh, Riken, Kiwame blah blah blah, then use them. End of story. Likewise with solder. Take your pick from normal 60/40, 2% silver loaded, 4% silver loaded, eutetic, lead-free, pain-in-the-arse, whatever whatever whatever… Don’t blame me if the resistors cost a lot of money!

Alright! Let’s start work!

I prefer the simplicity of shunt mode so let’s use it. However, typical shunt mode has this problem of “break-before-make”. Refer diagram on left.

What I hate about the configuration on the left is that, when the switch is in between 2 settings, full output of your source goes through. Not a problem with mine as my amp is only 0.7W but it still gets very loud on 97dB speakers. If your amp is 100W, you may have to pick up your drivers from the floor!

Of course, if you are lucky to find those “make-before-break” switches, then you’ll be fine. Otherwise, a better solution would be to wire it in the configuration on the right. No harm done when the switch is caught in “no man’s land”.

All’s great now and here are some values of resistors. Remember you need to determine how much attenuation you need. These resistance work fine in my system but may not be so in yours. To determine how much attenuation you need is easy. With a multimeter, find the resistances where you listen to at max and at min. Calculate from there and this is the range you need to focus on. How to calculate? You always measure 2 resistance. One from input to wiper (call this Ra) and another from wiper to ground(Rb). To calculate gain, use

   Gain = 20*log10[Rb/(Ra+Rb)]

Say you measured Ra is 90kohm and Rb is 10kohm, hence gain should be -20dB.

The second column is how much attenuation in dB for this particular setting. The equation to calculate this is “=20*LOG10($C$2/(C3+$C$2))” where $C$2 is 4700.

Likewise, 3rd column calculates the difference between this setting and the previous setting. Note that I don’t care much going from -35dB to -20dB, but stepwise, reduced to ~1dB after that. Point is, the settings where you will see the most use, you should have those little 1-1.5dB differences. But hey, it’s your pot, so don’t listen to me.

The last column just calculates what if with a 2V input, what will the voltage seen by the amp. Equation to calculate this is “=2*POWER(10,D3/20)”

Note that my step sizes aren’t consistent 1dB every time as I just want to use standard size resistors. Too lazy to series or parallel them. If you want uniform 1/1.5/2dB attenuation, then you need to recalculate carefully. A simple Excel spreadsheet will do just fine.

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Here, There and Everywhere

Here, making each day of the year Changing my life with a wave of her hand Nobody can deny that there’s something thereThere, running my hands through her hair Both of us thinking how good it can be 3655 Someone is speaking but she doesn’t know he’s there I want her everywhere and if she’s beside me I know I need never care But to love her is to need her everywhere Knowing that love is to share Each one believing that love never dies Watching her eyes and hoping I’m always there To be there and everywhere Here, there and everywhere

We have discontinued Maggie – the autoformer volume control, as we are developing something better, MUCH BETTER than ALL the transfomer volume controls we have tried. Watch out for her in April 2008!

Intro Ahhhhhh….. Elegance, Grace and Beauty. How else would you describe Maggie? Maggie is an autoformer volume control, designed and manufactured exclusively by the fine folks at Audiohobbyist.com And yours truly here got the most flattering honour of distributing such fine products, aligned with our aim of promoting great audio among our brethrens of this world! (Spread the word to our improverished brothers!) If you are wondering, why autoformer? Well, a true transformer volume control was built but the listening didn’t reveal that much of a difference. Could be that the autoformer is less lossy? However, the sonic difference between resistive pot and Maggie was totally unfair to… the resistive pot. To sum up in a very long line… smoother mids/highs, more “body” in the presentation, deeper bass, better dynamics/impact, (even at low volumes, you could hear the drummer hitting the drum hard and not slacking off)… But the best impression I get of Maggie is that, she makes the speakers “disappear”. I know this sounds like a damn cliched statement but I got less concious of the system. There’s something in the the music presentation! There’s something about Maggie… So after listening to Maggie, you’ll be wondering what the hell have you been missing in life listening to putty resistive volume controls. Ever experience the feeling of being in love for the very first time and that life before her was a big fat void?   Let’s face it. After your first taste of Maggie, you’ll be desiring for her, Here, There and Everywhere.

What’s the Impedance, Kenneth?   Maggie is about 60H in inductance. How does this translate to impedance depends on how “honest” you are. As Impedance is 2*PI*Frequency*Inductance, you could see that it depends on Frequency. So an honest guy may use 20Hz as a guide, thus the Impedance is 2*3.14*20*60 = 7.5kohm. Another guy may feel that there’s not much life below 40Hz so he uses 40Hz and arrives at Impedance of 15kohm. Worse still, someone crooked may go for 100Hz and claim Impedance of 37kohm!   So ask at which frequency is the impedance specified? Better still, just ask for the Inductance.

Dating Maggie

Hold on! Hold on! Shown here is just a prototype. We are still a few weeks away from ready to sell. Sit tight boys! She will be ready soon!

Still working out the details, like PRICE, and OPTIONS. Since she takes a godly 30 hours of manual labour to build (she’s a tough one, mate!), it’s no wonder there are sooooooo few such manufacturers in the world. Well, add AudioHobbyist to the list!

For Sale

	USD260 a pair for these babies. Shipping weight about 1.3kg.
	For a limited time only! 24-step switch to go with Maggie. USD18 each.

Wiring up Maggie

They are separated into 4 groups of wires, each with different colour heatshrink.

Alert! Alert!

Get your bib ready!

Fully assembled/tested in chassis, plug and play, ultra cool, autoformer volume control blah blah blah… better known as Maggie Passive Preamp. Call her Maggie TVC Passive Preamp if you wish to.

Isn’t she a beauty? Told you you’ll fall heads over heels over her! Yours for USD400.

There was a problem though. Shipping cost for the above unit was too high. Besides, having the trans inside the chassis yields not only a slimmer chassis, but allow stacking of components too. *hint: monica and charlize in matching chassis*

So this is the new standard version.

	Maggie Autoformer Passive Preamp!

We listened to you and it seems like many of you wish for a Maggie with multiple inputs and a selector switch. We’ll be offering this option soon.

Pride in craftsmanship

As you can see from the chassis above, we take pains to finish it as fine as we could, befitting Maggie’s stature.

Maggie Passive Preamp does not use the above switch but this much better made-in-Japan silver contact switch.

Measurements

Audiohobbyist isn’t afraid to show you some measurements! If you are looking for hard core specs, here’s some to appeal to your ANAL-ytical side. Ha ha!

Freq response

There’s a slight resonance at 70kHz but throughout 5Hz to 30kHz, we are talking about +/-0.5dB variation! +/1dB all the way from 5Hz up to 85kHz!
 Here’s more pics to knock you out!
Maggie’s distortion performance

1Khz THD = 0.025%

10Khz THD = 0.0235%

 Maggie’s inductance is 74 Henries.

When operated at 100Hz, the input impedance is 47kOhm.

At 10kHz, input impedance is 39kOhm.

At 20kHz, input impedance is 19kOhm.

 All these show that if we are driving Maggie with CD player with an output impedance of 600ohm, it’s ‘piece of cake’ to drive the above input impedance.
The last 3 setups above were tested with a dummy load of 4.7Kohm connected at step number 12, which simulates Maggie’s operation turned up to half of the volume. This simulates the load resistance of any amplifier in market, and 4.7Kohm
is the lowest input impedance of amplifiers in the world. We can’t find any amplifier that have lower input impedance than 4.7kOhm, meaning we are testing the worst case scenario here!
 
Take my Money! I want to Buy now!

How are we going to disappoint you? Go to our spanking new e-Store now! http://store.diyparadise.com.
 

diyparadise.com

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