Saturday, February 8, 2014

Nikon D800 Lightroom Camera Profile

I created my own Lightroom (Camera Raw) Camera Profile for my Nikon D800 and thought I would share it in case it was of any use to others. It is based on the Adobe Standard profile but removes the cyan cast in the blues and the slight magenta cast in the reds (skin tones look better in my opinion). It also rolls off the highlights in a more gentle manner which I prefer.

Download it from here or the Downloads page.

Thursday, August 15, 2013

Sunday, August 11, 2013

Soldano Reverb-O-Sonic Block Diagram

This diagram is useful those wanting to select tubes for certain positions in the amp but don't have the skills to read a full schematic.

V1 is the first tube behind the guitar input socket in the chassis, the next one along is V2 then V3 etc. Tubes V1 to V5 are 12AX7 (ECC83). Tubes V6 & V7 (The two larger power tubes) are 5881 or 6L6GC.

I would recommend a good sturdy tube for V3 as it is a DC coupled cathode follower and has high voltage between the grid and heater. (I would put a JJ or Chinese tube in here)

The 12AX7 tube is a double triode so contains two triodes in the same glass envelope, hence the reference to V1a & V1b etc. in the diagram.

Saturday, August 3, 2013

Soldano Reverb-O-Sonic Depth Control

Today I performed a modification to my 1995 Soldano Reverb-O-Sonic amp. These are wonderful sounding amps but lack some "low end" especially at lower volumes. Mike Soldano has provided a "Depth Control" for some customers so I contacted them and Bill Sundt sent me the details.

Its a very simple mod that consists of adding high pass filter to the feedback loop and using a potentiometer to dial in and out the effect. This is often called a "Resonance" control and can be thought of as the opposite to a "Presence" control.

1M (Audio/Log) Potentiometer
0.0047uF (4.7nF) Capacitor
1uF Capacitor

(I would recommend 100v or higher for the caps)

WARNING - These amps contain lethal high voltages which can remain present even when the amp is unplugged from the mains supply, do not attempt any modifications unless you know what you are doing.

Modification shown in red

You can fit the mod without any permanent changes to the amp by using the hole for the second speaker jack as a place to mount the potentiometer. I did this to start with while testing and then decided to drill an extra hole in the chassis as I planned to keep the mod in place.

The grey wire from the output transformer and the white wire from the speaker output jack are both originally connected together on the PCB just below a large capacitor. These two wires are desoldered from the PCB and then connected together and insulated with heat shrink.

A new screened wire (red/grey in this case) is connected between the outer lug of the potentiometer and the PCB, the screen is soldered (at one end only) onto the back of the pot. (A screened wire is not essential but good practice to keep hum at a minimum)

The 1uF capacitor is soldered to the centre lug of the pot. The other end is then soldered to the speaker jack via a new wire link (black) and heat shrinked.

The 4.7nF capacitor is soldered across the two lugs of the pot.

(I used a 500K pot and this gives plenty of boost)

Note the colours of the wires in your amp may vary so check the positions on the PCB carefully.

Final Modification

View From Back Panel