The culmination of all the hard work, experiments and listening tests of all the DIYers here! Most significant tweak has to be the “3 transistor mod” suggested by Paul Needs and Paul Hynes. Who would have thought we have such a bottleneck there? A major major upgrade in sonics in every way!

Shown here built up with the Paul Hynes regs and CCS2 plus 3 Audioslaves for the I/V stage.

Now offering mojo2 PCB.

Note that only one supply is needed as the PCB traces provide power to the individual regulators.

The PCB has been designed to fit Paul Hynes CCS2 and Regulators particularly the 5.4V and 0.83V regs. So no more string of diodes etc. If you prefer the simplicity of the original mojo, it is still being offered for sale. If you are budget conscious, you could build whichever reg you prefer and fit into mojo/mojo2.

mojo2 kit.

The kit has all the SMD components (resistors, capacitors and ferrite beads) soldered on so you only have to mess with the through hole components. [yes, thanks for the applause!]

It has everything you need except — regulators, Black Gates capacitors and output coupling capacitors. Oh yeah! Solder, elbow grease and the most precious commodity of all – time.

mojo2 map.

The map above shows CCS2/5v4/0p83 regulator pinouts.
If you fit in the Paul Hynes 5v4 regulator at “5V” location above, you only use Output and Ground.
If you are budget conscious, you could use Audioslave here or even a LM/LT1086-5V regulator as the pinout is the same – I, O and Gnd.
The rest of the regulators are straight forward.
The 12V and 18V regulators share the same pinout as the 5V reg, namely I, O and Gnd.
If you don’t want to use regulators here, just short I and O together but be careful with the CCS2 as it can’t take >17VDC.

However, due to the tight fit, the electrolytic capacitor of the CCS2 may come into contact with the solder joints on the 0.83V regulator, a simple suggestion of insulation tape on the top of the capacitor should do.

As mojo2 accepts EIAJ input, you could just feed EIAJ signal to it directly. Shown here is my current favourite digital player! Sounds best on a chopping board!

Though not shown, the ribbon cable feeds directly to the EIAJ input of mojo2.

The QA550 SD card WAV player reads bits and bytes directly from your SD card where a DSP chip does all the hard work here. This chip then outputs I2S signal to a CS8406 I2S to SPDIF convertor then outputs SPDIF downstream. This is where you hook up your DAC and let your digital receiver process this SPDIF and extracts I2S/EIAJ signal back to feed to your DAC chip.

Now, we could circumvent all this data processing and simplify it. All the attendant processing can’t be good for the signal no? Since there is already I2S signal onboard (straight from the DSP chip), we could feed to our I2S-DAC chip!

Monica’s TDA1545A requires EIAJ so here comes Black Crow! An I2S to EIAJ convertor board.

The above shows Black Crow’s pins directly mounted on the I2S pads of the QA550 which its designer very nicely provides us. The oscillator was also removed and now fed by a single supply version of a Kwak Clock 7. I’m too lazy to build one so I bought some DIYer’s version. [Thanks Patrick!]

So how’s the sound?

Going I2S is worth it! Installing the Kwak Clock (or some other low jitter design) pays off well!

Dare I say it?! Digital has never sounded so analog!

The post What’s better than mojo? mojo2! appeared first on diyparadise.

There are 2 Paul Hynes’ regulators we want to introduce here. Well, if you include the CCS, then there’s 3.

First, there’s the 5.45V regulator for TDA1545A VDD. Then there’s the 0.83V regulator for the TDA1545A VREF. Lastly there’s the CCS2 for feeding the 5.45V regulator.

So first step is to identify how to incorporate all these regs. Ideally we would like to place them as close as possible to the chip which we want to regulate its voltage. So in this case, we want to place them as close as possible to the TDA1545A chip, yet without leaving a mess of spaghetti wiring. (pray hard…)

Here’s what I did. Found that the best place to wire in the 5.45V reg is on the PCB where the 220uF cap is supposed to go. If you have both caps installled, then you could solder them at the bottom of the PCB.

Ditto to the 0.83V reg, best place is on the PCB where the 47uF caps reside. Note polarity.

Now there are many ways you could integrate these regs in. One way is to cut the PCB trace, disconnecting the string of diodes to VDD but if you don’t want to, you could desolder the 1N4148 diodes (all or at least both at each end).

The Paul Hynes regs’ pins are labeled I(nput), O(utput) and G(round). Descriptive enough? When mounting the 0.83V reg, I found it’s easier to desolder the I lead and wire it this way. This goes to the CCS2 input.

More pics here.

Aha… Integrated with Monica SPDIF-EIAJ module. Note that power for the module is taken from this mojo board. For better isolation, i put in a ferrite bead too.

Hey! Since we are on a roll, might as well add 2 more regs! Now there’s a reg for each channel of the SS I/V stage as well. [These new regs will be called ACDC in line with our preference to name our minor products over rock bands.] In order to do this, don’t install any jumper on LSUPPLY.

And so that’s what I did. So we now have regulators for every stage of Monica.

Err, this guide helps explain better how to power the individual stages of mojo.

And what does all this hard work give you?

Aye caramba! Muchhhhhhhh better sonics! SE-PA-RA-TION is superb!

Since I’m such a nice guy, for those who are more budget conscious, you could use AudioSlave here and retain the original CCS structure. You’ll need to break the PCB trace linking the string of diodes to TDA1545 VDD (pin 5) though. Err, with AudioSlave, you could go up to 25VDC.

There you go! Have fun!

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Rudolf Broertjes’ SS I/V Gain Stage

Greeings DIY brethrens!

Well ever since Monica conquered our hearts, there have always been questions from insatiable diyers asking for more more more!

Truth be told, Monica’s output is a little on the low side. Passive current-to-voltage conversion has its “beauty and beast” side. The beast side is of course current drive and low output. But the beauty… oh so beautiful… that I just feel that if we can’t find a suitable gain stage for her, then just let her be. Stay with this for now.

Then back in February 2006, CY “DAC Man” Liew shared with us his fabulous Grounded Grid Tube Gain Stage. If Monica sang before, now she’ll dance for you!

But DIYers will always be DIYers. Very soon, there were clamours for more, more, more again.

Then in February 2007, Ronald Verlaan shared on our forum this schematic by Rudolf Broertjes. Rudolf posted this schematic in diyaudio some moons ago.

Simple enough eh? The beauty of this circuit is that it sounds better than the vaccuum stage!

Plus you could power it at 12VDC though 18VDC is said to sound even better. For once, you could have your cake and eat it too!

I then contacted Rudolf but too bad he doesn’t have PCBs made for sale. I built a prototype and it’s rather time consuming. Besides without the benefit of a ground plane, noise issue etc could be a problem. So I requested Rudolf’s permission to build the PCB and sell to DIYers, especially Monica users.

And Rudolf agreed! So here you go.

Since this is not my design, and thanks to Rudolf’s generosity to share with all DIYers, I don’t want to profit from this. So the PCBs will be sold at a very low price, to cover costs, Paypal charges etc. You could order from our e-Store. http://store.diyparadise.com

Well, if that’s all to it, then it’s fine but I’m known to be a klutz many times. And this time is no different.

You see, when I built my prototype, for RSO1A, I used just a 82ohm resistor. And everything worked fine. Also, I couldn’t find any BF245A here so I went for the substitute of 2N3819.

As such, the PCB was designed for this.

When I got the PCBs in hand, then I realized a few things. Having a resistor instead of a trim pot for RSO1A is a BAD idea. Too many variations could give you problems. The LEDs’ forward voltage drop, transistor betas etc… All could affect the output DC voltage. Hence a few builds I did had output DC voltages ranging from 4VDC to 10VDC.

At 4VDC, Monica won’t sing at all. At 10VDC, she sings but off key (distortion!). This is why we want a trim pot! So to adjust output voltage to around half of VCC. So if you power her with 12VDC, then you want around 6-7VDC.

As such, there are a few mods we have to do here, no thanks to my clumsiness. Embarassing moments coming ahead…

For RSO1A shown above, we have R7 and R11 on the PCB. Have to fit in a trim pot in a resistor’s place! Fortunately it’s not as bad as fitting in a square into round hole… or something like that. This is how you do it. Carefully bend leg 2 to leg 3 and solder them together. Then spread it apart so that it sits in the PCB holes nicely.

Now if you prefer to use BF245A instead of 2N3819, there’s a bit more work for you too. You see, the semiconductor world is full of crazy folks who don’t understand “standardizations”. Source/Gate legs on both FETs are reversed! So BF245A has to “cross legs” and wear “stockings”. That’s heatshrink for you!

This is how it looks like. Shown here is for one channel only. Repeat for the other. My apologies again for this mess.

To integrate with Monica, this involves taking out components or if your soldering skills is suspect, just shorting them out. Err, either way you need to take out R19 and R20, then short the 2 inductors beside them all the way till C9 and C16. You could take out C9/C16 and use them at output stage of the I/V board and save yourself couple hundreds hours of running those darn Black Gates again.

A note about the LEDs. At first I tried those normal red LEDs but their forward voltage drop varies quite a lot between samples. In the end, I had to settle for these super bright red LEDs. They cost more but the forward voltage drops are pretty consistent. Only downside is you have to wear shades when playing music.

Okay, I exaggerated.

Building the SS I/V stage is very easy. Start off with resistors and diodes first.

R8, R14 — 820 ohm

R13, R16 — 100 ohm. Schematic above shows 270 ohm (RSI1) but as Rudolf himself said, 100 ohm sounds better.

R7, R11 — 200 ohm trim pot as shown above.

R9, R15 — is the critical I/V resistor. I recommend 3.3kohm if you use 12VDC supply. You could use bigger value with higher Vcc. Splurge on Kiwame, Holco, Riken, Shintoh… anything you like!

Next, we solder in the diodes. There are just 4 pieces of 1N4148 diodes. D2, D4, D10 and D14.

You could plug in the transistors now.

Q1, Q2, Q7, Q8 are all BC557.

Q4, Q5, Q6, Q10, Q11, Q12 are all BC547.

Q3 and Q9 are 2N3819s. If you prefer to use BF245A, then you need to cross its legs as shown above. Sorry again…

Now you can plug in those big fat LEDs. Be careful with orientation! + sign on PCB denotes LED anode – the longer of the LED leads. D1, D6, D9 and D8, D15, D16.

C13 and C14 of course is your output coupling capacitor. I recommend Black Gates N 4.7uF but you could choose anything you like. I left C12 and C20 blank but you could put in 1.1nF as shown in Rudolf’s schematic. Leaving it blank is good for now as we could measure across C12/C20 the output DC voltage.

Lastly C22 is the power supply capacitor. I use 220uF/25V Panasonic FM. Power input is labeled with pin 1 being the positive side.

Voila!

Upon power up, put your multimeter probe on C12/C20 and measure the output DC voltage. Adjust to around half of Vcc but it doesn’t have to be very accurate. I adjusted mine for 6.5VDC on both channels. I noticed couple minute upon power up, the voltages drift a little. Well, adjust again. After this adjustment, everything is fine.

I guess we are done now! Email or contact me if anything is unclear.

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Improving Your diyparadise Products

Yeah! Improve your already awesome gear!

What?! Improve these already kick arse products!

Yeah baby, we are talking about serious kick arse here!

Let’s face it. No design is perfect, every design can be improved upon. If someone says his design is “blameless” or “perfect”, you know that person has been boozing too much. Or maybe he’s some salesman.

So on this page, I’ll try to list down improvements you can make to your diyparadise products.

Up the value quotient!

Improve sonics!

Get your friends jealous!

blah blah blah… Okay, let’s start.

USB Convertor

The easiest and best improvement will be to modify the SPDIF output stage. Right now this circuit consists of a simple TTL-SPDIF convertor. Just solder the primary of your digital pulse trans across the vias labeled SPDIF OUT, and solder the secondaries to your output RCA wiring. You could use the Newava Technology S22083 1:1 pulse trans, available from Digikey. Or the Scientific Conversion SC982-04.

The more observant among you will notice that the Newave is a 1:1 trans while the SC is a 4:1. By right, the latter is more appropriate as SPDIF output is only 0.5V so stepping down the signal voltage is correct but I never noticed anything wrong using the former. So rest easy and just do it.

I don’t recommend you getting a toroid and winding some wires and passing it off as a digital pulse trans. Just because you use silver doesn’t mean anything at all. These trans are engineered/optimized for digital communication, not some hack job.

Charlize and Charlize2

Believe it or not, we have done so much work to Charlize2 that if you have the first version, just go grab the follow up version! I’m sorry but you can’t mod your 1 to our 2. [hey, you can’t mod your wife to look like Charlize okay?]

Guess the best upgrade you could do is to try various power supplies and see which works best. In our opinion here, nothing beats a high quality rechargeable sealed lead acid battery. Have tried various makes and all sound different. Read Graham and Denise’s report here.

Rudolf Broertjes’ Solid State I/V Gain Stage

If you have been following the diyers forum, you may notice that Ronald Verlaan and later Ole Schüsseler suggested LEDs instead of diodes for D2/D4 and D10/D14.

Another useful tweak is SUPER E the output Black Gates capacitors. I know these caps are facing extinction so please grab them now while they are still available [please don’t ask from me. Oh well, if you have to, they are 1000 EUROS a pop!] You know folks like to say Less is More but in this instance, More is the way to go!

This gain stage runs off at 12V but at higher voltages, she sounds better! Please be careful here as the power supply capacitor C22 is rated 25VDC only. So make sure you don’t go higher. [I use 24VDC myself and she’s been singing for months.]

The I/V resistor could be swapped to your personal preference. Use whichever audiophile approved boutique part as you (or your wallet) sees fit. My personal preference here is the excellent Riken Gold but as these parts are no longer in production, I’m sorry I can’t give/sell you any. [that’s not true. i’ll gladly trade for gold bars.]

Oh yeah, measure voltage across the I/V resistor and adjust the trim pot for half of your power supply. If this voltage is too high/low, some roughness or distortion may be present. Not good!

Monica2

If you have installed the RB SS I/V kit, the above applies but also, utilizing lessons from the USB Convertor’s digital pulse trans tweak, put the trans at the INPUT. Yeah,

RCA Socket —> 1:1 digital pulse trans —> Monica2 PCB’s digital input

Use the recommended Newava trans above.

Again on the forum, another forum member esidarapyid, recommended polystyrene capacitors across VDD/GND and VREF/GND on the TDA1545A chip. This is another awesome tweak! As these are bypass capacitors, the values aren’t critical. I had good results from 100pF to 1200pF. Silver micas are great too!

Then Paul Needs contributed another awesome tweak here. Instead of referencing Vref to 1/2VDD, Paul suggested referencing to one diode drop, thus the last diode. To perform this tweak, remove the 22kohm resistor (labeled “223”) and solder as shown.

Don’t be a klutz and short other pins. As always, solder/desolder ONLY on an electro-static safe sheet/mat, like the anti-static wrapper that houses your diyparadise product.

Paul also suggested giving a bit more current to the constant current source. Currently it’s set at 50mA but Paul suggested going for 70mA. To do this, you need to have about 18ohms at R10 in above pic. If you are lazy to desolder R10 and solder in a 18ohm resistor, you could just parallel a 100ohm on top of the 22ohm of R10.

Use Whitesnake!

I have been using various DIY 75ohm coaxial cables and have been pretty satisified with them until one day Gabriel suggested this white-colour-unassuming-but-thick-as-garden-hose cable. It’s so thick that I wondered how smart can it be?

Sorry for lame joke. Anyway, I tried it out and… Wow! Totally smoked whatever digital cables I had before. It was so good that one customer even ditched his purchase of a USD200 cable.

USB Monica

Right now we have the Enhanced USB Monica, but if you have the previous version, you could apply the tweaks to the RB SS I/V stage and also TDA1545 circuitry. Actually the Enhanced version already has these tweaks done. See how luck you folks are?

Note that the polystyrene Paul Needs tweak is not done on your PCB version. Only in finished products. [please don’t ask me for polystyrene caps either. if you wish, i’ll exchange for 2 gold bars!]

Aha! Since she’s software controlled, you bet your software has an effect on her sonics too! I like Macs here, as well as Linux. I stay away from Windoze as much as possible…

My sincere thanks to these gentlemen mentioned above for their ideas, suggestions and generosity.

Please note that the finished products (or “Plug and Play”) incorporate all the above mentioned tweaks.

Hey! Aren’t we on a roll here? Let’s continue…

Use wood!

Wood chassis really sounds beter. Looks better too!

Hifi products tend to look industrial, coming in cold soulless steel or aluminium, with little touches of wood for a “touch of class”.

Pure bollocks. Try housing in wood chassis and listen for yourself.

Not to be discounted, nor under-estimated.

Having a good brew in hand.

Silence in the listening area. Give your wife your credit card and ask her to shop for hours! [be smart. call the credit card company to cap a limit first!]

Great music. Please, not those audiophile crazy, sound effect mumbo jumbo junk passing off as music. I mean MUSIC! REAL MUSIC! You should be able to make an emotional connection with the music. Listen, appreciate, emphatize, celebrate… And stop all that analyzing shit. See, there’s “anal” in “analyze”.

Lastly, as with all diy projects, please exercise caution, especially with electro-static discharge, when performing these tweaks. I have said it before and I’ll say it again. The soldering iron is mightier than the pen/sword. But this doesn’t mean you could wield it like crazy. BE CAREFUL.

Good luck!

Improving Your diyparadise Products – Part 2

a. k. a.

How I Made My Friends Shit in Their Pants!

Oh yeah! If you did all the mods above PLUS these mods :

Bad Naughty Connector

Have never been a believer of cables and connectors but done right, with technical backing, I certainly ate the humble pie!

Powering Your Monica

Clean power, like clean water, is still the best.

I bet your friends will shit in their pants when they come over to listen to your system!!!

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