james david low

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Fender Blues Jr. Fat Footswitch with LED

I recently bought a Fender Blues Jr. with Billm mods. I wanted a Hammond 1590H footswitch to fit on my pedalboard.

The Blues Jr. footswitch circuit has a 15V signal that is connected to switch the fat switch. Billm suggests that you could use a LED and resistor and then bypass it so that the LED is on when the fat switch is off. However other companies offer a footswitch with an LED that is on when the fatswitch is engaged. I did some testing and I found that, at least with the Blues Jr. III, even with the LED and resistor in the circuit it still switches, so you can just break the circuit to turn it off. I think I calculated that an 800ohm resistor was about right.

Here’s a picture with the LED indicating the fat switch is on:

5:57am / Jan 4th / 15 Comments

Custom Neunaber ExP (3 Switches and other variations)

I wrote a previous post about my custom Neunaber ExP controller that uses a counter to switch between the 4 effects with just a single button.

3 Switches
I’ve had a few requests about how to do it with just switches. I’ve drawn up a circuit, but don’t have time to build it, so I can’t be 100% sure it will work.


– Neunaber don’t cover warranty for custom ExP controllers, I can’t be held responsible if you break your pedal.
– If you only want 2 effects, you can leave off the 3rd LED and switch
– The logic of the switching in this configuration is more like 2 banks of 2 effects with 2 presets each. Switch 3 selects between bank 1 (effects 1/2) and bank 2 (effects (3/4). Switch 2 selects between either effect 1 and 2 or effect 3 and 4 depending on the position of switch 3.

Common Anode
Another variation depends on the the type of multi-colored LED you use. Some have common cathodes, some have common anodes. You have to connect the common pin to the rail, and the individual coloured pins to E0/E1 because connecting the common pin would join E0 to E1 which you don’t want to do.


This also changes which colors indicate which effect:

Q1 Q0 Effect LED
0 0 4 Orange
0 1 3 Red
1 0 2 Green
1 1 1 (off)

4:41pm / Dec 1st / 14 Comments

Fender Superchamp XD Line In/Mute Switch Mod

I recently did a popular mod to my Superchamp XD. I put a line/poweramp in so that you can just use the tube preamp, without any of the digital or solid state that comes before it. At the same time I also added a poweramp mute switch so I could use the line out and play when son is asleep in the house. The line in mod will also mute the speaker when a cable is plugged in, but I put the switch in as well because its easier than finding a cable and plugging it in.

Tube amps can be dangerous. Always observe tube amp safety:

3:28am / Nov 29th / 14 Comments

Changing Batteries on a Mobee Power Bar

I used a Mobee Power Bar to save money and the environment by not needing any batteries for Apple’s Magic Track Pad. I use in plugged in all the time, meaning that I never run out.

However this does eventually kill the rechargeable batteries inside, and meant mine would keep losing the bluetooth connection and need to be re-paired. Anyway, had a thought the other day and unscrewed it and used a spudger to prize it open gently. Its basically two AAA NiMH batteries inside a AA case. I replaced the AAA with new ones, and things seem to be fine again.

5:23am / Nov 22nd / 14 Comments

Custom Neunaber ExP Controller

I recently purchased a Neunaber Slate pedal for the amazing Wet Reverb effect. However all the v2 of their stereo pedal range support up to 4 effects, with 2 presets per effect. They make an external controller to control this, but its a little too big for my Pedal Train Mini. You can see a demo in the video below:

Neunaber Slate: http://neunaber.net/collections/pedals/products/slate-stereo-effect-pedal-v2
ExP Controller: http://neunaber.net/collections/pedals/products/exp
ExP Specification: https://docs.google.com/document/d/1dtP4e3Sp2izZ9LJ1SC9TPAYDjfYPpU8mbfK4Lh-GG54

Here’s the circuit I used to build it:

Q1 Q0 Effect LED
0 0 4 (off)
0 1 3 Green
1 0 2 Red
1 1 1 Orange

– Neunaber don’t cover warranty for custom ExP controllers, I can’t be held responsible if you break your pedal.
– While my pedal works, I’m not sure if I drew out the circuit exactly like I made it :P
– While I’ve used a counter so that I can cycle through the effects with a single momentary switch, the same could be achieved with 2 latching switches or a rotary encoder: http://www.fk-industrie.de/en/produktkatalog/P/D/E/A/27.html
– I’ve used an up counter which cycles the effects in reverse 4-3-2-1. Use a down counter if you want to go the right way.
– When the counter sets the effect inputs to high, it also turns on the LEDs.
– I used a two color LED for L1 and L2. Mine had a common cathode, some others you buy have a common anode and may need to be connected to the +3.3V rail, with the cathodes connected to Q0 and Q1.
– Power is provided through the ExP port, I’ve just labeled the rails for clarity.
– Since the supply is 3.3V, you need a HCF logic chip (Not HCT which is minimum 5V).
– I wired the RJ45 cable directly into the box to save space, but there are some nice panel mount sockets around.
– I’ve drawn a switches only circuit here: http://jameslow.com/2014/12/01/custom-neunaber-exp-3-switches/

Counter: http://www.maplin.co.uk/p/4024-cmos-logic-hcfhef-qx13p
2 Color LED: http://www.maplin.co.uk/p/5mm-multi-colour-led-yh75s
Panel Mount RJ45: http://www.gtcontact.com/Ethernet-RJ45-Plastic-Screw-Panel-DIP90.html

3:51am / Nov 15th / 14 Comments

World’s smallest true bypass looper

I recently built a bypass looper into a Hammond 1590H pedal enclosure so I was doing some research into this. If you wanted to use jacks, and not have the LED, I realised you could use insert cables and fit two stereo switchcraft jacks and one of the small 13mm x 13mm DPDT footswitches that are avaliable.



I ended up soldering the patch cables directly to the footswitch and used strain relief gromets because I wanted to be able to fit a 3PDT switch, 9V power, and an LED indicator:

8:21pm / Oct 17th / 14 Comments

Western Digital Black² in a Apple Macbook Pro 13″

The Western Digital Black² is a 120GB SSD with a 1TB 7200rpm regular hard drive in a single 2.5″x9.5mm case. I thought it would be ideal for both expanding and speeding up my MacBook Pro 13″ without needing to use a hard drive caddy and remove the DVD drive, which I still use from time to time.

I went ahead and got one without realising it wasn’t compatible with a Mac. Since the move to Intel almost everything is these days, so I just assumed it would be. Not wanting to give up, I did some Googling and found that AnandTech reports that once partitioned using Windows, it is readable on a Mac.

Annoyingly you have to install the Black² as an internal drive in computer, otherwise the automatic partitioning tool won’t recognise it. I din’t have a Windows PC I could put this in, so I had to install it in my Mac first, install windows just to use the partitioning tool, and then copy back over my Mac OS. This is all the steps I did to get it working:

1) Backup your existing drive, its important to do this often anyway, but especially since this is not supported, I or Western Digital will not be responsible for any damage or loss suffered to you, your hardware, or your files.

2) Remove your old hard drive and install the Black² in its place.

3) Install Windows (I used Windows XP, so I also had to remove a ram chip to leave it with only 4GB RAM).

4) If on Windows XP SP2, install Windows Installer 3.1, download it onto a USB drive first so you don’t have to install the bootcamp drivers to get the WiFi working.

5) Run the WD Black² partitioning tool.

6) Hold the Alt key while booting and boot onto your backup or original hard drive on USB.

7) The Black² should now have two visible partitions. Erase existing partitions so that you’re left with one big one.

8) Create 2 partitions, the first one 119.8GB, and the rest for the remaining. I experimented with different sizes, but 119.8GB left the right block sizes (see appendix).

9) (Recommended) Add an additional partition of 1GB to the end of the first (SSD) partition you just created. I then cloned by old recovery partition using the instructions here. Update: I’ve changed this from optional to recommended, since when I tried to upgrade to OSX 10.10 Yosemite it couldn’t install because it wasn’t able to create the Recovery HD. I also tried to create it with Carbon Copy Cloner as a 650MB partition and that failed too. I don’t know if its because my partitions weren’t quite right and were overlapping the SSD/HD but when I created the Recovery HD as a 1GB partition it worked, and Yosemite installed.

10) Clone less than 120GB of your original or backup hard drive onto the SSD. If you have more data, you may need to clone your home folder on to the magnetic hard drive bit.

11) (Optional) If you have too much data for the 120GB, clone your home folder to the magnetic hard drive partition, and after booting up, move your home folder location.

12) (Recommended) Enable Trim. You can use Trim Enabler (paid) or what I used Chameleon SSD Optimizer (free). If anyone is interested, there seems to be an extra hardware controller in between the SATA and the drives to make sure trim command only effect the SSD not the magnetic partition.

There has been one or two settings that have changed on my Mac. I’m not sure if this is a result of moving my user home folder, cloning the hard drive, or something else. It seems unlikely that it would be because of using the Black², but I’ll report back as I’ve spend more time using the system. The settings changed were:
– Custom screenshot location overridden
– Mac gatekeeper changed from “All” to “Trusted”

Also strangely Western Digital do have a firmware update tool for the Black2 that does work on a Mac. I haven’t tried it, and not sure if I will yet.

– I just tried to update to Yosemeti and realised it won’t install if the partitioning scheme is master boot record instead of guid. I updated above to include these steps.
– In searching to fix the partitioning scheme problem I found that someone else has done this before, and also turned it into a full fusion drive!
– I also found this article helpful for how to check out the partition sizes in detail.
– Also since doing this upgrade I’ve noticed I get the the “Disk too slow (recording) -10004″ error when using GarageBand. I’m not sure if its the hard drive, or making the upgrade to Yosemite on an older Mac, but now I have to record to an external hard drive (not the one that the OS is on. I used to be able to do this when I had a normal hard drive. The disk isn’t slow, my boot times are at leas 6-10 times faster, but it maybe “glitchy” in a way that GarageBand doesn’t like.

Partition Block Sizes using sudo gpt show /dev/disk0

After WD Black2 Tool on Windows + Converting to GPT. I really should have done this before converting to GPT for it to be more accurate. From this you can see that the last block of the 1st partition should of the 120GB SSD partition should be at most 234420417 + 63 = 234420480 to be sure its on the SSD. In addition the start of the 2nd block should be at least 234442752.

start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 29
63 234420417 1 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
234420480 22272
234442752 1953523712 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
2187966464 319
2187966783 32 Sec GPT table
2187966815 1 Sec GPT header

After deleting original partitions and formatting to two partitions using Disk Utility and the first set to 119.8GB. Apple creates the EFI partition at index 1, so now index 2 is the 120GB we will store the OS on. The last block of this partition 233984376 + 409640 = 234394016 which is < 234420480. Apple also intentionally creates a large gap after any user partitions. This makes the first block of the normal hd partition start at 234656160 which is > 234442752.

start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 233984376 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
234394016 262144
234656160 1953048472 3 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
2187704632 262151
2187966783 32 Sec GPT table
2187966815 1 Sec GPT header

After I used Carbon Copy Cloner to create the recovery partition on the SSD, this is what I get:

start size index contents
0 1 PMBR
1 1 Pri GPT header
2 32 Pri GPT table
34 6
40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
409640 231887224 2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
232296864 262144
232559008 1835008 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
234394016 262144
234656160 1953048472 4 GPT part - 48465300-0000-11AA-AA11-00306543ECAC
2187704632 262151
2187966783 32 Sec GPT table
2187966815 1 Sec GPT header

8:12pm / Oct 17th / 14 Comments

Third Culture Parent

Just letting the world know that my wife has started a blog parenting products and all the things we’re doing to try and be intentional parents: Attachment parenting, baby wearing, reusable nappies, elimination communication.


5:32pm / Sep 12th / 14 Comments

Presonus iTwo with Garageband on iPad

I really miss my M-Audio Fasttrack 8R. M-Audio/Midiman had the most stable drivers and best customer support, until they were bought by Avid, and the sold again, decimating one of the best value midi/audio interface companies.

I sold the Fasttrack to downsize, but also because the drivers were becoming less and less stable on newer versions of Mac OS, and it became impossible to contact Avid without paying for support. I bought a Apogee ONE, but the Mic did’t compare to my old Rode NT1, and I missed being able to do 2 mics, or 2 lines at the same time.

I’m about to sell my ONE and get a PreSonus Audiobox iTwo (it wasn’t out when I got my ONE). I was trying to figure out if it would work with Garageband on the iPad for mobile recording, since in all the marketing they push their own app. I contacted their sales and go this reply:

“You can use Garageband; you’re not limited to just our recording app, no.

Conversely, there are people who bought our PreSonus Capture iOS app and use the built-in mic or other 3rd party audio interface on their iPad to track stuff when they’re out an about… so our software app isn’t limited to just work with our iOnes/iTwos.”

I also eventually aw that right at the bottom of the features they have a comment that it works with other apps on the iPad:

I sold an Apogee ONE for iPad because it would cause crashes on waking from sleep. I was going to get the iTwo interface, but decided on the Audiobox USB because it was cheaper. Unfortunately that interface doesn’t work with the iPad (unlike the Audiobox VSL 22). It gives the “device uses too much power” even when plugged in through a powered USB hub or one of these dual USB power cables and removing the power pin going to the iPad:

8:45pm / Sep 8th / 14 Comments

Dumble in a box pedals list

Always loved Larry Carlton and Robben Ford’s tone, and even tried to build my own Dumble clone at one point. It didn’t sound good, and I didn’t have the expertise or time to make it sound good. Anyway, 13 years later and I’ve moved on in the music I play, but I still get GAS for that tone. Recently there have been more and more pedals trying to get that sound, and some of them are starting to come close. Here’s a list of the ones I know of:

I’ve owned both a Fishbone (Zendrive) and an SOV-1. When I compared the two the Fishbone sounded closer to me, less saturated and more touch sensitive. It was also smaller and didn’t run off mains voltage, so I kept it. Having heard demos of the Simble I was tempted to get one of those, however recently I’ve just bought a Fulltone Fulldrive 3 to replace my Fulldrive 2. I found that with the comp-cut mode, I could get close to the Dumble sound too. I hope to put up a comparison soon, but first impressions are, the FD3 comp-cut sounds more open and transparent (something I wanted out of the Simble) and is even more touch sensitive than the Fishbone, but a little bit more saturated when playing harder. The fishbone has a more pronounced midrange, making it to my ears sound more like Robben Ford, and the FD3 comp-cut more like Larry Carlton.

Update: Here’s a demo of the Fulldrive 3 (Comp-cut mode):

Oh I almost forgot, there was also the infamous Freekish Blues Joyo Alpha Drive

3:20am / Aug 24th / 14 Comments
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Fender Blues Jr. Fat Footswitch with LED / Custom Neunaber ExP (3 Switches and other variations) / Fender Superchamp XD Line In/Mute Switch Mod / Changing Batteries on a Mobee Power Bar / Custom Neunaber ExP Controller / World's smallest true bypass looper / Western Digital Black² in a Apple Macbook Pro 13" / Third Culture Parent / Presonus iTwo with Garageband on iPad / Dumble in a box pedals list / Low cost made in China pedals / Small single-pedal sized multi effects / Pedal and amp list / Fulltone Fulldrive 2 Circuits / Ikea Standing Desks / Who I'd like to see in the dunk competition / Top 10 things I am missing about HK, enjoying about the UK / Simultaneous MIDI/Audio with Apogee ONE for iPad / iPhone Repair Bristol / Disable Git in Eclipse / A New Language for App Engine / iPhone Push Notifications with JavaPNS on Google App Engine / Midi Keyboard Velocity Curve Calibration With Pianoteq / Top 10 things I will and won't miss about Hong Kong / List Apps To Update After Moving iTunes App Store Countries / DynDNS via curl on Apple TV 2 / iOS-WebStack with Apple TV 2 firmware 5.2 (iOS 6.1) / Fast Track Ultra 8R in Mountain Lion / Google DFP with Appcelerator Titanium / Alternatives to Google Apps / Digitech iStomp and the new iPhone 5 lightning connector / The case for wired keyboards / Cornerstone vs. Versions vs. SmartSVN / Use of Foxconn and other manufacturers / iPhone Screen Setting / Pedal Board / New Family Friendly Homepage / Tip for efficient living / Detecting Quercus / Amazon S3 for WordPress with CloudFront / Database Read Replicas / Force User Login Multisite / Moving Church / Top 10 things I love about living in Ocean View / My Paper / iPhoto '11 No Place Smart Album / Creed / Random OSX Hacks / Getting Married :) / Diddy Feet / Very helpful error message / Apple LED Cinema Display with a PC / Simply Christian - N.T. 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