[IN STOCK] Eurorack 4hp THAT2180-based Audio VCA

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Kent, luketeaford, Joe.

Post Reply
User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

[IN STOCK] Eurorack 4hp THAT2180-based Audio VCA

Post by negativspace » Sat Jan 04, 2014 2:40 am

This is a single THAT2180 VCA on a 4hp Eurorack panel. The PCB is similar in size to my other 4hp modules and it should work just as well in shallow cases & skiffs. It has a log CV response and is AC-coupled, so consider this one to be for audio only. As you'd expect from a THAT chip, it sounds fantastic. Another compact, "clean audio" module to go along with the mix.

Unlike most of my small-board projects there's no room on this one to add the MOTM power header or mounting holes. I'll still be happy to sell you boards without panels, but you're on your own as far as getting them into your preferred format is concerned. The pots are set 1" on center & are Alpha 9mm-type parts if you choose to go with board-mounting.

I've reposted littlem4tt's image here, it shows the trace cuts (green) and jumper (blue) that need to be done to rev 1.2 PCBs.

Image Image

BOM

Resistors
[7] 100k
[2] 20k
[1] 10k
[1] 4.12k
[4] 1k
[1] 330R
[2] 100R
[1] 1KTC SMT

Capacitors
[1] 10uF Electro (audio path)
[1] 4.7uF Electro
[1] 1.5nF Poly Film
[1] 22pF Ceramic
[2] 47uF Electro
[3] .1uF Ceramic
[3] .1uF 0805 SMT

Pots
[2] Trimpot (20k)
[1] B or C50k Alpha 9mm
[2] B100k Alpha 9mm

Semiconductors
[1] 5.1V Zener Diode
[1] TL074B
[1] LME49710
[1] THAT2180B
[1] LM78L05
[2] 1N4001

Misc
[1] 10P 2-row Header
[2] PTC Resettable Fuse (.05h/.1t)
[2] Ferrite Bead
[4] Kobiconn 16PJ138 (Jack)

Calibration Procedure:

1) Red probe to the pad on the PCB marked TP. ("Test Point") Black probe to ground.
2) Set offset control to max CW (full volume) or insert a +5V CV source into one of the inputs.
3) Use the trimpot labelled 'zero' to set the voltage @ 'TP' to 0.000V or as close as you can get.
4) Set offset to max CCW. (off)
5) Use the other trimpot to set voltage @ 'TP' to 305.00mV, give or take ~3mV (~1%).

It should then open fully to unity gain with a +5V CV signal. The 5.1V zener diode should limit the offset + incoming CV sum to ~5.14V, so if you mash it up to the diode's break point you'll get a little bit of positive gain with the unit trimmed to unity at +5.00V. If you want to ensure you get no positive gain, max out the diode by applying a CV signal greater than ~5.3V and calibrate to unity at that point.

If you like distortion I encourage you to tweak the trimpots to taste as you can really overdrive the chip by setting the zero-point (step 3) to a positive value. (*this is from memory so forgive me if I got something backwards...) The 2180 sounds really meaty when you overdrive the shit out of it. This is not a bad distortion module if patched/set up that way. 8_)

Alternative CV sensitivity is possible - you can set it up to accept 8V or 10V signals by changing the zener diode to an appropriate value and trimming as above. A different LM78Lxx regulator can also be used to supply the appropriate voltage to the offset control.
Attachments
[ma] THAT2180 VCA.jpg
[ma] THAT2180 VCA.jpg (157.04 KiB) Viewed 876 times
Last edited by negativspace on Sun Feb 15, 2015 4:05 pm, edited 11 times in total.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sat Jan 04, 2014 2:40 am

Prices
Eurorack Panel: $15/ea [280]
Bare PCB: $10/ea [289]
Shipping: $3/USA, $8/Canada, $10/Overseas
The Paypal address for payment is jcoates42@gmail.com
Last edited by negativspace on Sun Feb 15, 2015 3:42 pm, edited 55 times in total.

User avatar
Reality Checkpoint
Confused By Electricity
Posts: 3924
Joined: Wed Apr 15, 2009 4:06 am
Location: Al Aqsa

Post by Reality Checkpoint » Sat Jan 04, 2014 3:37 am

Excellent!

Please can you put me down for:

1 x panel

1 x PCB

Shipped to the UK.

Thank you. :party:

User avatar
Ginko
Super Deluxe Wiggler
Posts: 1587
Joined: Thu Jul 18, 2013 6:27 am
Location: Unfortunate
Contact:

Post by Ginko » Sat Jan 04, 2014 3:46 am

2 panels and 2 pcbs please again to the UK - and there is a big gap in my euro waiting for your svvcf!!! :hihi:

User avatar
woodster
Super Deluxe Wiggler
Posts: 1353
Joined: Mon Mar 05, 2012 9:36 am
Location: UK

Post by woodster » Sat Jan 04, 2014 7:24 am

I'm down for 2x PCB and 2x Panel delivery to UK.
Is it possible to add to the Mindreader and 4x4x4 shipment, or will there be too long a wait between them going out?

Ginko really does speak the truth about the SVVCF.
Me, I'm trying to be Discrete :hihi:
Last edited by woodster on Wed Jan 29, 2014 4:36 pm, edited 3 times in total.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sat Jan 04, 2014 7:53 am

Yeah, yeah, I hear you. :hihi:

This thing was only about two hours away from being done, though. It's been through 3 board revisions and two panel changes. I've got almost $2000 invested in parts and prototypes. It's time to finish it and get it out the door...

The SVVCF is next. There's nothing else on my plate. It's still 2 solid weeks of layout/prototyping away from being ready, but at least I can focus on it now.

User avatar
EATyourGUITAR
has no life
Posts: 6136
Joined: Tue Aug 31, 2010 12:24 am
Location: Providence, RI, USA

Post by EATyourGUITAR » Sat Jan 04, 2014 7:55 am

those electrolytic caps look a bit bigger than they need to be. you can get electrolytic caps in

6mm = 100uf
5mm = 47uf
4mm = everything else

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sat Jan 04, 2014 8:00 am

The supply decouplers are a nice, squat 47uF that I use in several modules and the input coupling cap is an Elna Silmic. Both fill their footprints as shown. I'll reiterate that I've been through 3 prototypes already... :hihi:

aristote
Common Wiggler
Posts: 61
Joined: Fri Dec 06, 2013 6:12 am
Location: France

Post by aristote » Sat Jan 04, 2014 11:27 am

2xPCB and 2xPanels for me please (+ shipping to France). :)

aristote
Common Wiggler
Posts: 61
Joined: Fri Dec 06, 2013 6:12 am
Location: France

Post by aristote » Sat Jan 04, 2014 11:27 am

2xPCB and 2xPanels for me please (+ shipping to France). :)

Cablebasher
Wiggling with Experience
Posts: 434
Joined: Sat Aug 03, 2013 6:51 am
Location: England, UK.

Post by Cablebasher » Sat Jan 04, 2014 11:56 am

1 x PCB, 1 x panel, shipped to UK.

Thanks.

hv0190
Common Wiggler
Posts: 185
Joined: Fri Sep 10, 2010 1:52 am
Location: Munich

Post by hv0190 » Sat Jan 04, 2014 12:04 pm

2 x PCBs to Germany,
thanks!

CometxYh1n1egyPt
Common Wiggler
Posts: 88
Joined: Fri Mar 25, 2011 9:15 am

Post by CometxYh1n1egyPt » Sat Jan 04, 2014 2:03 pm

Hi,
Can you put me down for 1 pcb and 1 panel please.

Thanks,
Luke

User avatar
gbiz
Super Deluxe Wiggler
Posts: 1076
Joined: Tue May 07, 2013 11:20 am
Location: Sussex, UK

Post by gbiz » Sat Jan 04, 2014 4:20 pm

2 x PCB & 2 x panel please. Also to the UK.

User avatar
Stab Frenzy
Ultra Wiggler
Posts: 882
Joined: Wed Mar 03, 2010 5:46 am
Location: Melbourne

Post by Stab Frenzy » Sat Jan 04, 2014 5:19 pm

What are the three pots for? Initial gain, input CV attenuation and something else?

Either way I'm down for 2x pcb and 2x panel, might double that before the cutoff though.

User avatar
analogdata
Common Wiggler
Posts: 129
Joined: Sun Nov 18, 2012 4:11 am
Location: Carcosa

Post by analogdata » Sat Jan 04, 2014 5:22 pm

2 panels and 2 pcbs (to sweden)

User avatar
Nantonos
Super Deluxe Wiggler
Posts: 1275
Joined: Sun Mar 03, 2013 1:00 pm
Location: Boston, MA

Post by Nantonos » Sat Jan 04, 2014 7:11 pm

One panel and one PCB please (to France).
ondes | current rack
I am afraid a firmware change will not be able to turn a rather expensive 16-bit DAC into a 16-bit ADC, and flip all those op-amps :)

User avatar
zodiak
Common Wiggler
Posts: 185
Joined: Tue Dec 24, 2013 3:57 pm

Post by zodiak » Sat Jan 04, 2014 7:50 pm

I am new to this format and am interested but couldn't work out how front panel and PCB are fixed together. Is it just the pins on the 3 pots, or am I missing something?

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Sat Jan 04, 2014 7:51 pm

May i have :

1 x Panel

1 x PCB

Shipping to Australia.

:sb: :sb: :sb:

User avatar
cleaninglady
Super Deluxe Wiggler
Posts: 1271
Joined: Mon Aug 24, 2009 8:04 pm
Location: creeping up behind you

Post by cleaninglady » Sat Jan 04, 2014 7:53 pm

zodiak wrote:I am new to this format and am interested but couldn't work out how front panel and PCB are fixed together. Is it just the pins on the 3 pots, or am I missing something?
Once the pots are soldered into the PCB the pots go through holes in the panel and then are fastened to the panel with the nuts on the pot shafts. :party:

User avatar
yan6
Ultra Wiggler
Posts: 981
Joined: Sat Jun 15, 2013 7:14 pm
Location: Ontario, Canada

Post by yan6 » Sat Jan 04, 2014 9:09 pm

One pcb and panel shipped to Canada please

User avatar
apophis93
Common Wiggler
Posts: 60
Joined: Thu Oct 24, 2013 10:09 pm
Contact:

Post by apophis93 » Sat Jan 04, 2014 9:22 pm

2 x Panel + PCB, man need to catch up on the stuff I already ordered from you ;)

User avatar
dropmotif
Common Wiggler
Posts: 147
Joined: Tue Apr 24, 2012 5:24 am
Location: Los Angeles

Post by dropmotif » Sun Jan 05, 2014 12:04 am

Great! Two PCBs please. US shipping.

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sun Jan 05, 2014 5:39 am

apophis93 wrote:2 x Panel + PCB, man need to catch up on the stuff I already ordered from you ;)
I sometimes wonder how many of my modules are hidden away in backlogs... most of what I offer are quick builds, though, so maybe not as many as I fear. :hihi:

User avatar
negativspace
Manhattan Analog
Posts: 6574
Joined: Tue Apr 13, 2010 2:50 am
Location: Manhattan, KS, USA
Contact:

Post by negativspace » Sun Jan 05, 2014 5:43 am

woodster wrote:Is it possible to add to the Mindreader and 4x4x4 shipment, or will there be too long a wait between them going out?
These won't be ready to ship for about 6-8 weeks... ~3 for orders, ~3 for manufacturing, ~1 to ship to me, plus any delays that might pop up.

Post Reply

Return to “Music Tech DIY”