Drip Opto 3 Manual

drip opto ver 3
Instruction and build manual revision 1.0
optical compressor
atom version
copyright 2008 | gregory lomayesva

Attention|disclaimer
This project is presented as artwork, and is solely intended
As such.
Although this board can be assembled and
Built into a functioning optical compressor.
Due to the high voltages and possibilities of
Human error , drip electronics | gregory lomayesva
Hereby assumes no liability for injury/damage/loss
which might unintentionally occur.
This manual is intended for information purposes only.
Proceed at your own risk.

Warnings|caution
It is important to cover a few safety tips and cautions before you
begin.
1. This project has high voltages, at some places on a live
board voltages can be upwards of +300v @ 380 mA.
It is not a terrible amount of current/voltage , and I have been
shocked many times for foolish mistakes such as forgetting the unit
was powered on while servicing it etc.
It’s enough voltage to remind you to never make that mistake
again.
For someone with a heart condition this voltage can be lethal.
2. Once the unit has been powered up , the filtering electrolytic
capacitors (c7a-c7d) will remain with charge in them for
a period after the power has been switched off.
I found that a shock also is still possible for a few moments.
(It seems the NE-2 neon light helps dissipate charge after power
off.)
3. Never ‘lift’ or remove the safety ground (chassis ground from AC
cord).
The board with proper wiring and ground layout will have minimal noise
and hum ,
solving a hum problem by lifting the safety ground is wrong, often il
legal and dangerous to you and others.
4. Work off of an ac plug that is grounded to earth.
5. If the fuse pops on the pcb or a circuit breaker , there IS something
wrong , stop ,re check all connections and review your work.
the fuse will only pop if there is a short or a miswired connection.
6. Do not rush through the project with out reviewing your work
several times . beware of solder bridges .
sloppy work or impatience is dangerous to you and others.
7. Be neat in your connections and wire runs, don’t use more wire then
is needed for each connection.
if you can’t be ‘neat’ , don’t bother with this project.
‘Neatness promotes accuracy’
8. If the electrolytic capacitors are mounted in reverse , they can
explode violently . REMEMBER THIS. CHECK EACH ELECTROLYTIC !.
9. if you do not understand something fully that is not covered
in this manual or are unsure about something. STOP.
and ask a question either in the forum or through email.
you will be helped.
10. This unit is intended as a mono unit , and was not designed
for anything but the ‘rated’ power transformer.
11. The use of a ‘vented’ case IS necessary.

designed by gregory lomayesva | copyright 2008

1. the pcb has been designed around the circuit and not the compo-
nents. Creating the shortest paths to each important connection
2. pcb uses 3 oz copper
3. a new ground plane has been added using the heaviest gauge of
of copper possible .
(ground scheme still follows the original design separating
the reduction/audio/input transformer circuits.)
(also aids in shielding the audio circuit below it)
4. the use OF SPRAGUE ATOMS or equivalent filtering electrolytic
capacitors.
5. use of pcb mount 1 meg potentiometers for stereo adj/lim response
and optionally zero adjust, thus eliminating additional wire runs.
6. pcb is .93”thick
7. pcb is silver plated.
8. tube heaters have dc reference circuit built into board
(Further protecting ac hum from entering the audio circuit)
9. a grid resistor has been added for the 12ax7 in the amp section.
10. an extra 1k resistor has been added to the Pi filter in the
power supply.
11. the diode footprints are now made for fred/hex diodes (to-220)
12. quench arc snubber has been added on board for the power switch
(to control popping noise on power down)
13. 68 pf cap has been added in parallel to r11 to help prevent
occilations.
14. 2nd pad connected to ground has been added for connecting gain
2 and reduction 2 (giving option to omit ‘y’ cable
when connecting potentiometers)
15. ‘x-cap’ has been added to the primary of the transformer
(hf noise filter )
16. resistor footprints are large enough for carbon comp.
17. capacitors foot prints in the amp section are made for
poly-pro caps
18. option to select ground circuit for the output transformer
(into audio gnd or reduction gnd)
19. most trances are 2mm wide on 3 oz copper
(almost 20 times the needed copper)
20. Entirely new design of circuit balancing a compact
Design but ensuring separation between traces.
21. pcb mount sowter transformers
22. Optional grounding through standoffs
23. heater traces moved to bottom of board
24. entire circuit on one side of board (no overlapped traces)
25. grid resistors for 12bh7a
26. Insulated 5.08 screw connectors can be used for all connections
27. Circuit is ‘true’ to the original 1960’s design
28. heater traces on board (no heater wiring)
features

Design notes| history | theory: as also in some camps of thought ac heated tubes ‘sound better’
and is speculated to prolongs tube life.
a dc heated board will be available in the near future.
but by keeping the design AC , readily available power transformers
can be used , eliminating the need for custom jobs.
the design allows the use of a 6.3v 2amp DC power supply.
if wanted simply route the 6.3 dc into the pcb heater pads.
in heavy experimentation with fully regulated high voltage
power supplies and dc regulated heaters ,
this design and early prototypes kept shining though
with almost equivalent specs.
the hv power supply remains a full wave dual diode type
as found on the original unit , but the addition of fred diodes
and use of cde tc series or atom capacitors is a very effective
upgrade.
Although this design does not replace the ver2 opto pcb
it does explore many new concepts and ideas in tube circuity design.
the design layout was made by hand over the course of a year.
the goals were to revolve the circuit around the shortest Connections
Possible ,
often designers rely on component placement first ,
circuit second , with the advent of more advanced pcb design programs and
auto routing Capabilities , it seems that designers are more
Interested in simply connecting a circuit then taking the time to balance
the form and Functionality of it .
there is no ‘rats nest ‘ in this design , it is elegant as it is
functional.
i chose the design based on a flower type interconnection to the
vacuum tubes insuring a greater separation to protect against
interference from adjacent tracks.
great care has been taken in the design of both the amplifier
section and the reduction circuit.
the use of a ground plane has also helped in creating a more
compact design , yet continuing to maintain the original grounding
concept of the original unit :
separation of the audio,reduction,high voltage and input transformer
ground.
thank you for your interest in the new drip opto ver3.
the ver3 is a whole new design and layout based on the
classic ‘la’ compressor/limiter circuit.
this design is true to the schematic of the 1960s compressor
but many new features have been added to the design ,
Including a dc referenced heater circuit , and the use of
Sprague atom or cde tc series filtering capacitors.
the pcb is compatible with most equivalent audio transformers ,
but the use of sowter transformers is recommended for a seamless
build.
a lot of time,testing and prototyping has gone into this board
Assuring you the highest in quality and performance.
under many circumstances, the pcb can stand side by side with most commer-
cial and vintage units and give equal results.
the opto3 pcb uses ac powered heater filaments , but much effort
has gone into routing the heater traces away from critical
Components.
in many tests the ac heater circuit on the opto3 are as quiet as dc
rectified circuits.

your opto’s foundation began as an artistic approach in symmetrical design.
by not compacting the circuit and allowing for great amounts of space
in between traces , cross talk is kept to a minimum.
“Neatness promotes accuracy.”
it was my goal to create a pcb that is compliant to electrical standards
and of a quality rivaling most commercial products.
Compared to other manufacturers of la-style compressors ,
you will be able to use the highest quality components and still come in
under half the price of most retail units .
throughout most of the pcb you will find up to 5mm wide traces on
important connections like the optical cell and the c5 capacitor section
by using 3oz copper ,it equates to a 15 mm wide trace as compared
to commercial pcbs meager usage of 1 oz copper and .5mm wide traces.
please enjoy this latest release from drip electronics.
g.

here is a chart showing side by side comparison of a properly
wired opto3 pcb and other LA style compressors.
(how ever this was not done in a laboratory and should only be
used as an example of the performance possible with this pcb.)
in the frequency response , the opto 3 (light blue) seems to hold it’s
ground in comparison with a brand-x point to point unit.
(the vintage la2 seems to be using the jumper network found on old
units , dipping out from 30hz to 600hz )
as far as noise floor , the opto3 in green seems to do very well.

all machines calibrated to 0 db digital with 1k test tone
vintage la2 was running on filtered ac studio mains.

reduction/
gain pots/
limiting
switch
ground hook
up
input trans-
former/xlr in
optical
cell (t4)
dc refrence
circuit
xlr
out
meter
sw/bottom
vu
meter
zero
ad-
just
meter
sw/top
output
trans-
former
c5
capaci-
tor
12bh7a
tube
12ax7#1
tube
12ax7#2
tube
6aq5a
tube
gain 2
hook up
reduc-
tion 2
hookup
frequency
response
LAMP
POWER
SWITCH
ATOM
ELECTRO-
LYTICS
STEREO
ADJUST/
LIMITER
RESPONSE
POTS
POWER
GROUND
HIGH
VOLTAGE
IN
6.3V AC
(HEATERS)
IN
XFORMER
PRIMARY
AC IN

info|build order
1.) install resistors and jumpers
2.) install capacitors
3.) install tube sockets / octal sockets
4.) install transformers if using pcb mount.
5.) install _fuse clips and fuse
6.) connect ground leads and solder tags
7.) connect pots
8.) connect switches
9.) connect XLR’s
10.) connect ac section
11.) connect vu meter
12.) power up / power down
13.) install tubes
14.) pass audio test
15.) troubleshoot
16.) install t4
17.) begin squishing audio
to start is simple , using the build order on the facing page ,
you will begin by placing all the components on the pcb,
and solder them into place .
2 notes on soldering : always clean your tip of excess solder after each
use , ALWAYS CHECK FOR SOLDER BRIDGES after each component is soldered.
What’s great about the pcb is if all the parts are placed correctly .
you will get identical results over and over.
only the transformer will cause any variance in b+ voltage(main power).
but this can be adjusted by raising or lowering the value of r29.
the ideal b+ voltage is between 250vdc and 275vdc , some people prefer
250v and some prefer 275v , back in the 60’s plus or minus up to 20%
was okay , but with the advent of 1% resistors you can achieve more precise
Voltages over and over.
the pcb allows the use of 5.08 mm spaced insulated headers for your
Convenience in attaching wire to board , but i recommend soldering directly
to the pcb for the power section and also the gain and reduction potentiom-
eters .
be sure to take great care in double checking the values of the components
you place , in most instances, the value on the pcb legend will be covered
by the component once placed on the pcb .
if one component is misplaced or the wrong value is soldered , the entire
circuit can fail , damaging many other components like the tubes and the
valuable optical cell .
after populating the board with all the components and transformers ,
you will place the board in it’s case and begin attaching all the wires
to the pcb ,
take great care and time in attaching each wire to the pcb .
make sure each wire is not to short , but also not too long ,
leave a little slack in each wire so it can be either secured to the case
or like in the power section have enough room to allow for separation.
if you follow the instructions in the manual , your first power up
should be successful , but always close the lid on the case when you
do this , for if you made a catastrophic error like soldering an electro-
lytic back wards , it wont explode in your face.
info|how to start

to start the project you will need some basic tools.
Depending if you have purchased a pre-drilled enclosure.
or if you are fabricating your own case.
for basic assembly you will only need a few tools.
solder/wire snips/needle nose pliers/wire strippers/screw driver and
solder
one of the most important tools will be your soldering iron .
the radio shack 40 watt soldering iron is a great buy and works well.
however you will never regret purchasing a 200$ digital weller model
as shown above.
tools:

parts|info

parts | optical cell
for compression you need to purchase a t4 optical cell.
nos t4bs are very good , despite many of them were made
over
20 years ago .
universal audio sells replacement t4’s , and they work
great.
drip electronics makes limited runs of opto cells every
8 weeks .
each drip optical cell is crafted by hand using heavy
gauge
pure copper and a 3oz copper double sided pcb with sol-
der mask.
each cell is computer analysed , tested then matched for
optimal
Performance.
urei NOS cell
drip optical cell
The compressor section of the opto revolves around the optical
cell using cadmium sulfide photo cells in tandem with a electro
luminescent panel,
this is what gives the release time of the compressor it’s
smooth characteristics.

parts|resistors|info
The original resistors in a vintage unit are carbon composition
allen bradley 1/2 watt +/- 10-20%.
Carbon comp resistors are believed to have a ‘warmer’ sound then
metal film resistors.
Yet often at a price of more noise and less reliability.
there are alternatives to consider in your selection,
a company called ohmite has a new carbon comp resistor brand called
‘Little Demon’.
As for metal film resistors , some brands are state of the art
with tolerances down to ‘0.01%’.
Metal resistors are quiet, accurate and reliable.
The sound of metal film resistors can be more preferred then carbon ,
The capacitors and transformers can make up for any short
falls of that ‘metal sound’.
Avoid metal oxide resistors for anything but the power distribution
resistors , (the resistors that ‘feed’ off of the main power rail).
r29(2watt)/r33/r35/r34(2watt)/r16/r28/r17
Often I use 1-2 watt resistors for these sections.

Most all the resistors that you use will be 1/2 watt except for
r29 4.7k and r34 22k these will be 2 watt resistors (metal oxide).
In different camps of thought , some say higher wattage resistors
have less noise , feel free to experiment with this.
Installing the resistors is easy ,
I recommend a resistor bending
tool, this will speed up the process
and keep the resistors looking neat and
straight.
Most of the resistor bends will all be
the same size.
NOTE :DO NOT USE 1/4 watt resistors!
however tempting this might be .
the voltage in some places on the
circuit near or overlap the operating
range of them.
resistor bending tool
‘speedy bend lead former’
mouser#5166-901

parts|capacitors|info
for the project you will use two types of capacitors ,
electrolytic which are one way components that must
be aligned in the proper direction .
and non polar type caps that can be placed in any direction
please take note of the electrolytic , and use caution.
positive +

NOTE :electrolytic caps must be aligned properly.
there is a ‘positive’ and a ‘negative’ lead.
on the pcb , the positive side is marked
with a plus ‘+’ symbol.
Electrolytic caps can explode if placed
in reverse.
Electrolytic capacitors :
The pcb uses 6 electrolytic capacitors :
c5 : 10uf @450v (axial mount)
c7a : 47uf @450v (axial mount)
c7b : 47uf @450v (axial mount)
c7c : 22uf@450v (minimum)(axial mount)
c7d : 22uf@450v (minimum)(axial mount)
c10 : 47uf@25v (axial mount)
dc ref : 22uf@450v (radial mount)
one of the greatest advantages of the pcb is the ability
to use sprague atom capacitors , they are regarded for
their tone and reliability .
how ever CDE makes an equivalent capacitor the ‘TC’ series.
a lot more expensive then the atoms , but they are modern
and very good performers.
ive had great luck using 4 40uf@450v capacitors for
c7 a,b,c,d ,
there are some advantages to using up to 100 uf caps
for c7a and b these two caps are part of the PI filter
of the power section .
c7d and c are usually 22uf , but i would stick to 40 uf
caps here.
each electrolytic footprint is clearly marked with a
positive symbol and a ground symbol , it is essential to
place the cap in correlation to these .
failure to do so can cause the cap to explode
positive + negative-