Wednesday, 30 July 2014

Native Instruments Master Class - Pro Sound & Lighting

This Native Instruments Master Class was held on the night of Wed the 30th July at Pro Sound & Lighting Studio in Wollongong, Australia.

Thanks to Claude of  Pro Sound & Lighting and Mike from CMI Music & Audio for organizing this event.

It was a great chance to trial out some of the latest gear that NI (Native Instruments) had on offer.
I was particularly interested in checking out the new MASCHINE STUDIO & TRAKTOR KONTROL S4

DJ Kuya demoed both the Maschine & the S4.
He is a 3x DMC Victorian Champion, 1x Australian ITF Champion!!

DJ Kuya explaining the Maschine & Traktor setup

Maschine looks like it's a solid host for VST/AU plug-ins and effects.
It's basically a hardware sequencer that hosts soft synths.

 Machine Mikro

Machine Studio (Pro version). 1 midi in & 3 midi you can drive external synths or drum machines and even sync Maschine to external MIDI clock sources while at the same time being able to assess your arsenal of VSTs, plug ins & soft synths. 

Machine Studio - smaller than the Pro version. I think it would be great for live performance.

Tuesday, 29 July 2014

TTSH Synthesizer - Two Thousand Six Hundred - 4012 Filter (DIY)

The filter build of the TTSH synthesizer. 
This is part 7 of my TTSH (Two thousand six hundred) build which is an ARP 2600 clone synth.
You can see my full build thread HERE

I understand this filter is based around the coveted Model 4012 filter, a four-pole low-pass VCF.
The 4012 filter used a design that closely resembled Moog's ladder-filter. This led to a legal dispute between Moog and ARP which forced ARP to design a new filter for their later models.
All the early ARP 2600 (pre 1977) used this filter. It's one of the reasons why the early Blue Marvins,  Grey Meanies, the (pre 1977) 2600s & 2601 v1.0 sounded so good.

The original design uses 8 pairs of matched and thermally coupled TZ-81 and TZ-581 transistor pairs.
There is a Dual FET AD3958, a LM301 Op Amp & temperature compensation via a 1K87 tempco resistor.

The TTSH combines the filter sub-module with the additional main board filter circuitry. 

Post 1976, ARP used the model 4072 filter (which was in turn replaced with the ARP 4075 4-pole 24dB low pass filter in the ARP Odyssey Mark 3, Omni and Quadra).

Some pics of the almost virgin PCB first:

 This is the back of the PCB

And the front section

Resistors & diodes first as usual.

These are Multilayer Ceramic Capacitors MLCC - Leaded 47pF 50V.
The BOM specified 50pF (as does the original 4012 schematic) but the Mouser order number (810-FK28C0G1H470J) shows them as 47pF.
I hope the slight discrepancy won't cause problems.

Caps & headers in.

The original 4012 filter used 8 pairs of matched and thermally coupled TZ-81 and TZ-581 transistor pairs.
The TZ81 was a NPN made by Sprague.The TZ-581 is a PNP trannie

The TZ-81 is now defunct. The TTSH uses the 2N3904. (its modern equivalent).
The TZ-581 is also defunct. The 2N3906 is a modern equivalent.

This is what the PCB looks like before the transistors:

Some of the trannies need to be matched.
First insert the unmatched transistors:

 This is a 2N395. It's a dual JFET

2N395 pinout

 Unmatched transistors.

There are lot's of ways to match transistors.
Vbe (base-emitter voltage) Vs  Hfe (current gain). ????

And the question of whether its really needed in this case is debatable.
Modern manufacturing tolerances are far tighter than back in the 70s.
I'm buying all my transistors in a single order so they should come from a single manufacturing batch. I guess that matching will only make a difference when your trannies come from several sources.

I'm testing each PCB as I go along & … I'll swap for matched pairs at a later date if I need to.
So far I've not run into any problems, but I found that thermal coupling (
thermal compound between the transistors) seems to help.

Anyway, Muffs has a cool thread for DIY Transistor matching if you finally wish to go down this path..
matching transistors - DIY
Vbe (base-emitter voltage) matching is the most common type of matching.
Eg: the famous tester of Dr. Robert Moog.
Moog assumed you have a +/-10V supply. He measured the base to emitter voltage.
You need a volt meter capable of reading to 0.001Volts DC.
(Sadly my VC97 meter only does 2 decimal points. ... time for a new one I think)

MFOS has a great page on how to build transistor matchers.
(MFOS Practical Transistor Matching)

At the moment I'm using a cheap digital multimeter. (Vichy VC97) with a a hFE mode.
(It's useless for Vbe matching).

Matching hFE is really easy to do. First define whether your trannie is NPN or PNP,
 then insert the emitter, base & collector into the appropriate hole.The DMM calculates the hFE for IB (In fractions of a mA I think). The value will be displayed on the LCD.

IB = base current
IC = collector current
hFE = DC current gain = IC / IB
The hFE varies with the current draw, the temperature & the applied voltage ... so I guess if we want to be really precise we should measure this all under the circumstances the transistor will see in its working environment.

These are my 3904s sorted in order of hFE

Same with the 2N3906s

Tempco 1k87 resistor.

The transistor ladder of hFE matched 2N3904s

Trimpots finally.

Monday, 28 July 2014

TTSH Synth - The Human Comparator - VCO 3

Finally the third VCO of the TTSH synthesizer.
This is part 6 of my TTSH (Two thousand six hundred) build.
You can see my full build thread HERE

The VCO3 section before population (well almost)

Resistors & Diodes first. Then caps, headers, etc.

Install trimpots on the front side of PCB

 Almost there. 

This is what the front PCB looks like now.

Now to test for the waveforms.The square first.

And the ramp. Yahoo !!!

Sunday, 27 July 2014

Machu Picchu - Peru

15th-century Inca site located 2,430 metres above sea level. It is located in the Cusco Region, Urubamba Province.

Most archaeologists believe that Machu Picchu was built as an estate for the Inca emperor Pachacuti (1438–1472).

It was unknown to the outside world before being brought to international attention in 1911 by the American historian Hiram Bingham.

Thursday, 24 July 2014

Say It - Buchla & Elektron OctaTrack Jam

A Cobramatic & JonDent jam. Sunday (20th July,2014).
The Elektron OT fits very nicely with the Buchla

Wednesday, 23 July 2014

TTSH - The Human Comparator - ARP 2600 Replica - VCO 2

This is part 5 of my TTSH (Two thousand six hundred) build.
You can see my full build thread HERE
There are two awesome TTSH threads in Muffs.
2600 clone - Two Thousand Six Hundred (TTSH)
Two Thousand Six Hundred (TTSH) Project General Build Thread
The DSL-Man site has a very good TTSH thread
And of course the official build thread is here

The 2nd VCO has four waveforms: sine, pulse, saw, ramp.
It's my favoutite VCO

 Rear panel view

Front panel view for VCO 2

First install resistors, IC sockets, MTAs if you like.

Install trim-pots, caps, etc.

This is a ultrarare transistor.

3.5mm jacks The one on the left is from Thonk.

The PJ301BM jack from Thonk on the left is ideal for the TTSH project.
The one on the right is a standard (modified my me) 3.5mm jack.
It's simpler just to get the ones from Thonk.

The jack needs to be installed on the sine VCO. Then test with your scope for the relevant waveforms.

You will need a 2N3906 & 2N5172
The 2N3906 a common PNP bipolar junction transistor.
The 2N5172 is a NPN.