Monday, 30 October 2017

MXR Stereo Chorus - M205

 The MXR dates from around 1983. Its very heavy.

 It's a great sounding pedal

The era of BBD based delays & chorus appears to have just been very short . Between 1976 and 1983 ?
So this comes from the very end. It appears that pedal companies all released digital  based delays in the 1980s killing the demand for the BBDs.

Uses a Reticon SAD4096.... super long delays.
 The SAD4096 is super rare. It's a general purpose 4096 bucket (2048-sample) n-channel BBD. It's useful where a long delay is required. (2ms to 250msec). The delay is controlled by the clock frequency.

The RC4558 is a texas Instruments General purpose dual Op amp.
The MCI458p is also an op amp
The SCL4013 is of course a CMOS logic chip. Dual flop flop.
The CD4013 provides an excellent clock source with their Q and -Q outputs.

Saturday, 28 October 2017

The Clifford Pier - Singapore

Located at the first floor of The Fullerton Hotel Singapore this beautiful and historic building is well worth a visit.
Built in 1933, it was a landing point for immigrants and a ferry terminal to the southern Islands like Kusu & St. Johns. It was the melting pot for the interaction of different races and cultures.

In the early days, the car park surrounding the entrance was transformed into a hawker centre. It was the meeting point for musicians, night owls, and lovebirds. Today it's still a meeting place but it's been transformed into a something very stylish.

Click here for more travel postcards

Thursday, 26 October 2017

MXR Time delay

Picked this up on Ebay.
I am addicted to Reticon bucket brigade chips. So couldn't pass this one up.

Heavy, and built like a tank.
This one dates from around 1981 to 83.
M206/Series 2000
Serial No. 206-001729

The seller described it thus:
"This is a supremely luscious vintage analog delay. Thick, decadent delay repeats you could cut with a butter knife. Forget that Panasonic/Matsushita malarkey: Reticon did it right."  Yes !!!!

Reticon SAD4096 bucket-brigade delay chip with in'n'out running through a NE571 compander. It's socketed as are the op-amps (MCI458p)

....SCL4013BE ... CMOS chip ,,, its a dual D-type flip flop

 Built with love in beautiful Rochester

Buchla Easel - Portabellabz bob expander.

These are my build notes for the Bucha easel BOB by Portabellabz.
You can find the docs here .
It's quite a neat little unit. And it's expandable.

The two ICs are a TL071 op amp and a CD 4093. The TL071 is I think used to invert the EG.... the second left output jack.  The 4093 is I think used for converting gates to triggers ???... for the pulser trigger out ???

The trimmer sets the voltage level of the pulse trigger out. ... If using eurorack the voltage level of the pulse out can be reduced to 5V

Papz has left a section on the right blank to add your own circuit.
I'm putting in a square wave LFO/audio oscillator which you can find in the build notes.
I first tested this on some bread board.

Used just one 741 op amp, one capacitor (220nf) & 7 resistors.
The uber basic circuit is here
It's about as simple a circuit as you can get. An op-amp with positive and negative feedbacks.
The inverting input is connected to a RC (resistor capacitor) network. The non-inverting input is connected to a voltage divider.
It's classified as a astable multivibrator which has two states, neither of which are stable. It is constantly switching between these two states with the time spent in each state controlled by the charging or discharging of the capacitor through a resistor. The op-amp works as an analogue comparator... comparing the voltages at its two inputs.
The full schematic is here:

 Yup. It works both as a modulation oscillator and a audio oscillator.

Now to build it into the board.

So the the connections from left to right are:
- sequencer pulse in
- envelope inverted out / envelope trigger out (switchable)
- pulser pulse in
- pulser trig out (the internal short pulse occuring at the end of its cycle, not the ramp on yellow bananas)
- MO modulation switch CV
- LPG1 mode switch CV
- LPG2 mode switch CV
- LPG2 signal routing switch CV
- extra oscillator - switchable between LFO & Audio.

Wednesday, 25 October 2017

Ibanez FL-303 pedal

Vintage Ibanez FL-303 Flanger.
Picked this up the other day on Reverb.

 Great sounding pedal. Runs on two 9V batteries.

speed (or rate), width (range or depth)
Regen : The regen (intensity or enhance) knob feeds some of the delay output back into the input.
It intensifies the flanging effect

 The delay Chip is a Reticon SAD 1024. My favourite BBD IC.

The MCI4013. ... CMOS Dual D-type Flip flop. ?

SN72L022P .... I think it's a dual general purpose low power op amp, using the standard pinout for a dual op amp (same as a TL082, LM358, etc.)

For more on SAD 1024 BBD - Bucket Bridge devices

Saturday, 21 October 2017

EHX Big Muff - Basic build

This must one of the most studied, rebuilt, cloned, copied circuits ever.
The famous Mike Matthews Electro-Harmonix Big Muff guitar pedal. Pink Floyd used it. So did the Smashing Pumpkins. Jimmy Hedndrix gave it immortality. The list of artists is endless.

There are countless variations too. You can buy kits on the net with PCB & parts supplied to save you the hassle of understanding the circuit. But I like to know how things work. I'll build this on perf board.
So here is the basic circuit.
So how does it work?
The signal comes in through R2 and C1 before hitting the first stage, a basic transistor signal booster (Q4). Once the signal is boosted, it goes through C4 and enters R24 (the sustain potentiometer). This controls the gain. 

The signal goes through C5 and R19 before hitting the next stage, which is doing 2 things. Boosting  and clipping the signal. The clipping is achieved via the diodes (D1 and D2) & C6/C12.

The signal then goes through C13 and R12 before hitting the next stage : tone control.
It's identical to the previous diode clipping stage apart from the tone pot (R25) which pans between a high-pass and a low-pass. This explains why when you turn the tone control down the sound is very bassy, while turning it up cuts the bass, and it gets very bright.

After leaving the tone pot, the signal goes through C3 and enters into the final signal boosting stage before exiting through C2 and going out of the volume control into the pedal’s output.


Many thanks to Kit Rae for a wonderful website.
If you haven't visited it yet here is the link:
This is the site to go to for everything you could ever need on this topic.

The first pedals came out in the late 1960s and over the last nearly 60 years the designs have barely changed. It says a lot about how good the basic design is. Of course there has been lots of tweaking over the decades. At one point the four transistor design was changed to op amps. And for another one of those decades Electro-harmonics transferred production to Russia.

Today the company is strong and still building Big Muffs. I highly recommend the modern versions (I own a few and love them) but I think it is fun and educational to explore the older variations. These go for astronomical prices on Ebay & Reverb today. Vintage "Triangle" and "Foxey Lady" pedals regularly change hands for over $1500.
If you can afford the real vintage thing go for it as I think nothing really beats vintage components. They have a persona which only the years can give. But probably the only chance I will have to experience something like the vintage sound will be to build my own.  So below is a brief comparison between the different variations. It's a great way to explore the evolution.

Starting with the early "Triangle" pedal

Triangle V1

Circa 1971 Circa 1971/2 Circa 1972-73

R2 33k 33k 33k
R3 100K 100K 100k
R4 2.7K 2.7K 2.7k
R5 33k 33k 39k
R6 10K 12K 12k
R7 390K 390K 390k
R8 33k 33k 39k
R9 470k 470k 390k
R10 150R 100R 82R
R11 15K 15K (or 12K) 22k
R12 8.2k 8.2k 8.2k
R13 15K 10K (or 15K) 22k
R14 100K 100K 82k
R15 470k 470k 390k
R16 100K 100K 82k
R17 470k 470k 390k
R18 10K 10K 12k
R19 8.2k 8.2k 8.2k
R20 100K 100K 82k
R21 100R 100R 150R
R22 100R 100R 82R
R23 1K 820R 820R
R24 100K 100K 100k
R25 100K 100K 100k
R26 100K 100K 100k

C1 0.12uF 0.1uF 0.1uF
C2 1uF (or .1uF) 0.1uF 0.1uF
C3 1uF 0.1uF 0.1uF
C4 1uF 0.1uF 0.1uF
C5 0.12uF 0.1uF 0.1uF
C6 0.12uF 0.1uF 0.05uF
C7 1uF 0.1uF 0.05uF
C8 0.01uF 0.01uF 0.01uF
C9 0.004uF 0.004uF 0.004uF
C10 500pF 500pF 500pF
C11 500pF 500pF 560pF
C12 500pF 500pF 560pF
C13 0.12uF 0.1uF 0.1uF

Q1 2N5133 FS36999 FS37000
Q2 2N5133 FS36999 FS37000
Q3 2N5133 FS36999 FS37000
Q4 2N5133 FS36999 FS37000

D1 1N914 1N914 1N914
D2 1N914 1N914 1N914
D3 1N914 1N914 1N914
D4 1N914 1N914 1N914

The values seem to have changed slightly over those 3 years.
There is a lot of scope to do some tweaking to find that sound that's right for your needs.
Maybe play around with carbon vs metal resistors? In the 1970s those carbon resistors would have been 10% tolerance or more ???

R24, 25 & R26 are the pots.  
Vintage USA Big Muffs (V1, V2, V3) used single-gang, linear taper, 24mm,100k potentiomers.
A possible future mod could be to use B100K for R25 & R24 & A100k for the Tone (R25).
Log pots (A-100K type) have a longer usuable mid position and less at the ends. ... better fine tuning.
Could be useful for the tone section.

 Leakage current for the 1N4148 as 5 µA .... I think the same as the old 1N914

What transistors to use???
They need to be NPN bipolar
BC549C, BC550, BC239, SE4010, and 2N5210 work according to Kit Rae.
2N5088, 2N5089, MPSA18, 2N3904, 2N4401 are possible candidates.
It might be best to use sockets to allow experimentation.
Were the transistors matched in the early pedals?

Kit Rae's valuable diagnosis identifies three sets of components which alter the BMPs the most.
1. The clipping blocking caps. (C6, C7)
2. The feedback / filter caps. (C10, C12, C11)
3. The Tone stack filter. (C9, C8, R8, R5).

The clipping blocking caps
" C6 & C7 determine the bandwith to be clipped by the diodes". They are usually identical in value and have a great effect on the sound. The smaller the value, the more bass. From the photos I've seem it looks like these are ceramic.

Feedback Filter caps;
C10,C12,C11 usually have identical values. They determine how buzzy/fuzzy the pedal sounds. "They filter the amount of high frequencies. Larger values roll off more highs and smaller values give more crunch and buzz to the sound. The better sounding vintage Big Muffs tend to have the larger values and sound smoother and warmer. Modern Big Muffs tend to have the lower values and sound a bit more buzzy/fuzzy." (Kit Rae).

The pics of vintage units indicate ceramics.

The ToneStack filter.
These 4 components surround the tone pot (R25).
C8, C9, R8 & R5. This section influence the mid frequencies. The more mids that are removed, the deeper & darker will be the sounds and the more the muff will probably stand out in a mix. The two resistors determine the amt of mids removed. Looks like 33K was the most common value for R8 & R5.
"Higher values have less mids scooped out and lower values have more mids scooped. This resistor also works in conjunction with the high pass tone capacitor (.0004uF in the example above) to affect the treble at low tone settings. Reducing this cap to .003uF alters the range and scoops slightly more mids. Increasing to .004uF reduces the scoop. Combined, a larger high pass cap and smaller resistor decreases the treble at low tone settings." (Kit Rae)

The pics of vintage V1 boards suggest C8 is a polyester  & C9 be ceramic.

Muffs Guts (Kit Rae)
Electro-Harmonic's Time Line

To be continued......

Electrofringe 17

Cant wait for this.
Electro Fringe 2017

I'll be helping Andrew (Virusinstaller) perform a set at EF17 .

A post shared by jono (@dj_jondent) on
Electrofringe's #EF17 is creating a cosmic rip in 107 Projects to liberate artists, hackers and musicians into Sydney's expanding space of electronic art. From scattering rays to altering consciousness, EF17 sets an open platform for experimental ideas, practices and techniques. Interact with bioelectrical machines, dance to a raw music program, and learn how to mousejack your housemate's computers all for FREE over one day

This is a sample

A post shared by jono (@dj_jondent) on

Saturday, November 4 at 1 PM - 11:45 PM
107 Redfern St, Redfern. Sydney

Thursday, 19 October 2017

EHX -Little Big Muff Pi - "The Op Amp Muff "

Some pics of this beautiful vintage pedal.
It's a Electro-Harmonix Little Big Muff with the rare Op-amp circuit.
Up until 1978, the traditional Big Muff circuit used four transistors.
But in an effort  to reduce costs operational amplifiers were substituted. These versions can be found
in the V4 & V5 PCBs. Model Numbers: EH3003A, EH3003B, EH1322, EH1322B, EH3003.
Some of the same circuit boards used in the Big Muff V4 were also used in the Little Big Muff
The Big Muff has 3 knobs: Volume, Tone & Sustain. The Little Big Muff only has a Volume knob.

The Op-amp versions are often describes as "grungier" than the traditional transistor designs.

The PCB is labelled EH-1322.
Thus its a version 4 or V5.
Its the Op-amp version.

The RC4558 is a Dual General Purpose Op-ap.

The UA741 is also a general purpose Operational Amplifer.

The Pot ID: 1377840.
Thus the date : The 40th week of 1978
 The Muff guru Kit Rae describes the Op Amp Muff thus:
"I am including this as a legitimate Big Muff, even though it was not built on the classic Muff four-stage circuit. It was intended to sound like a Big Muff and was released in the same box as Version 3, so I feel it must be included as a true Muff version. Plus, I, and many others like them. It has a huge, crushing Big Muff sound. Though not quite the same as the organic transistor tone, is was very unique. Supposedly only a few thousand of this version were made".

"Version 4 is likely the Big Muff circuit heard on most of Smashing Pumpkins' Siamese Dream and Pisces Iscariot albums, so that should give an idea of the potential of this version. This is the rarest of the two op-amp Big Muff versions".(

Electro-Harmonix Time Line
KitRae - The BigMuff OP Amp version