Amplifier Jack Socket Stomp Switch Variations
Do you have an amp with no footswitch, but are put off by the sometimes extortionate prices for manufacturer’s Name replacements, even used ones on Ebay? Have you considered building your own? It may be really simple, if you have a chassis, can solder and have a drill. I did this one in 40 mins or so:
The aluminum chassis was from Ebay for 5 quid, the stomp switches about 1.50 each, and the jack socket about 2 pounds.
I am writing this as there may be some beginners who are new to amps, or just none techie players who don’t know how these switches and jacks work, and think their only option is to buy the exact same manufactures pedal – Marshall, Vox etc. – else it won’t work right, if they have an amp with this facility but no pedal.
This is often the case with 2nd hand amps as the pedals often get lost, if not hard wired like my Fender Champ 12.
My Marshall, Ashdown and Vox amps all came with no pedals.
As I recently discovered that the Ashdown Fallen Angel has a “boost” LED on Channel 2, under the control knobs, it made me think it may be just what I want in this amp for the specific tone and level change I am looking for in any one of my amps, for a nice Solo sound, but not just from a Channel change.
Looking on the back I found a jack socket marked Tip – Channel 1-2; Ring – Boost.
This made me look on Ebay for the Ashdown pedal for this model – no luck, wrong type or too pricey.
As this has a stereo jack socket it can only be switching on and off from tip to earth and ring to earth, as stated, the tip switching between channels 1 and 2, and the ring switching the boost on or off.
It seems to work by allowing more signal to flow through one side of the ECC83 valve’s cathode at pin 8 with the boost occurring at frequencies dictated by C23 and R43. When the stomp switch is open circuit, the Field Effect Transistor TR3 is switched off, so the boost is off – I think? Yes – because this would be the same as having no jack plugged at all – the default.
I thought I may as well buy the bits and build a stomp box myself.
Other simple Channel or single FX switching pedal makes like Marshall, Crate and Vox from Ebay should do in most cases, but again they were too pricey for what they are built of in my opinion. You are just paying for the name. The Vox pedal cost more than I paid for the whole amp at 35 quid!
My only prior experience of these stomp switches was when I had a Sessionette 75W with a 2 channel and reverb foot pedal back in the late 80’s (great amp! Loud!), just like this but in cream:
Slightly more complex ones like the Session pedal above may have LEDs to show which function is active, which is great for dark gig moments, but these may have more wires in the link cable to power the LEDs. You may want to consult the schematic for these cable types and connectors like DIN types:
I am only covering passive mono and stereo jack connector types in this article.
The cables for these may differ also – a single core with earth braid or dual core with braid (microphone XLR type cable). XLR cable can be used for both obviously.
The plugs that go at each end are also known as Tip Sleeve (TS) and Tip Ring Sleeve (TRS) types:
Their more common use would be for audio signal transfer – historically used for telephone switchboard systems, with the plug acting as the signal path and the operator plugged switch, simultaneously.
For the stomp switches they are used as open and closed circuit return paths via earth (braid) only.
The dual core cable is used for mics also with XLR plugs and sockets:
I make my own guitar, mic and stereo leads up by buying say, a 12m length of Klotz XLR mic cable (2 core and braid).
The Neutriks jacks are the industry standard jack plugs, so 6 of these at 99p each from various Ebay sellers, with a 12m length of Klotz XLR at 1.60/metre + post from the same supplier, with bulk buy postage reduction is around 20 quid total. I can make 3 x 4m lengths say, with this. When a new 3m lead from a street audio/music shop can cost that much, it’s a lot cheaper, and gives you flexibility on length or type of lead.
For a 1 core guitar lead with earth, I just solder the two cores of the XLR cable together to make a thicker single core, and use the braid for earth as this is paramount in noise reduction. On microphone connections that are used in Pro environments, they are usually plugged in to line balanced sockets, which means there is a noise cancelling and impedance matching transformer in the XLR mixing desk connection. This noise cancelling principle is known as Common Mode Rejection. It occurs because the noise that does get through the outer cable braid is induced on both core wires simultaneously. Each wire connects to opposite ends of a transformer. As the noise is in phase on both cores but travelling in opposite directions through the transformer it cancels out.
There a various sockets that TRS/TS jacks can push into depending on circuit function – schematically:
They may open and/or close other signal pathways when inserted, such as FX on or off like the Marshall’s simplest example of turning the Tremolo section off by simply shorting that signal path to earth, when the mono cable is plugged in and the stomp switch is closed:
They may connect FX Send and Return loops on the back of some amps, like the Ashdown, which is a closed circuit unless an FX is plugged in so that the signal is diverted to the effect, then returned to where it would have been, by the return jack.
Incidentally, when servicing an amp with FX Send/Return, it is worth spraying Servisol type switch cleaner into these Send and Return jacks, then inserting a jack plug a few times vigorously, to clean the inside socket connections, as they can get dirty or corrode a little from lack of use, breaking the closed signal path for 1 guitar channel or another, depending how the amp is designed.
Jacks could close the power amp path to the speaker while opening a headphone socket path via a power soak resistor instead, like on the Ashton kit amp output section where the circuit to the outputs are open unless there is an insertion of a stereo headphone jack to close the path to the 16 Ohm jack and take it to the headphone jack:
It’s a bit tricky to read and follow as this socket type has 9 connections and when the stereo jack is plugged in, the mono signal from the Yel 16 Ohm path is fed to the headphone socket and split into two and shared so that each earpiece has the same sound at points 2 and 3, after the bulk of the signal has been power soaked by the 15 Ohm 7W resistor to earth, so full valve power doesn’t go to the headphones – if I’m reading it right?
You can use a stereo cable and jack in a mono socket usually, as they are the same length, so the tip and earth still connects properly. Using a mono jack in the stereo socket will mean the ring is permanently shorted to earth or the insulation between rings leaves it disconnected so you won’t be able to switch this.
I am waiting for stereo jacks and sockets to arrive to make my stomp box properly, but to test the boost function in the mean time, I just soldered a mono socket and a mono lead to the amp, but only pushed the plug in far enough so that the tip of the jack touched only the ring of the socket. I could still use the pedal to kick the boost in then to check it out.