Following on from my previous article on matching amplifiers and loudspeakers, this article offers some ideas for making passive dummy loads. Active dummy loads are fine, but if you need to test an expensive amplifier at full load, you do need to be pretty confident that you are connecting a load which is going to… Read More »
Note: Some amplifiers will be very unhappy if you max them out without an appropriate load – and inappropriate could mean open-circuit, short-circuit or just too high or too low. This article covers the basics of connecting loudspeakers to amplifiers – in this case I am thinking of solid-state guitar amplifiers which are generally going… Read More »
We don’t do much SMD (surface mounted) work here at Stompville. When it comes to the True Bypass Relay however, smaller may just be better, so we designed and built a surface-mount version to see how small we can realistically make it – and the answer is about 30% smaller. That is 30% smaller on… Read More »
Update: Please see also Phantom Piezo Preamp revisited Update: Phantom Piezo Preamp modules are available for purchase in the shop here. A few years ago, Alex Rice put a design up on the internet for a phantom-powered JFET piezo preamp. Here’s the schematic of the original design as reported by Zach Poff: So far so… Read More »
Idss for the 2SK596s JFET – as introduced in my previous blog – is an order of magnitude lower than (say) a 2N5457, so I have been revisiting the design of my Arduino-based automatic JFET matcher to be sure that I can use it to characterise the 2SK596s with good resolution. Along the way, I… Read More »
UPDATE: The 2SK596S is discontinued from OnSemi. I bought some 2SK596S-C low noise JFETs. The device comes in a type SPA (SC-72) package similar to TO-92 (shown above on the right for comparison) and is otherwise notable for having very low Idss. It seems there were originally two versions of the 2SK596S (ranks A and… Read More »
Update: Kits available in the shop here. I finally got round to revisiting the manual JFET matcher project. Please take a look at the earlier article and refresh yourself on the details of the three tests we can perform to help match JFETs: Vgs(off) – which we approach with a gate-source resistance of 10M Ohms… Read More »
I’ve been looking at using an encoder as a front panel control. Encoders are industry standard devices made by ALPS, Panasonic, Bourns and CTS among others. They come with and without a push-button switch and (not-counting the switch) have three terminals, labelled A, B and C. We can connect the C terminal to +Vcc or… Read More »
I thought I would make myself a crib sheet for the basics of designing with op amps. Then I thought I may as well post it here so I won’t have to remember where I put my crib sheet. This will be an ongoing thing. The subject is: Analogue audio design using op-amps with single-ended… Read More »
Update – extra schematics and timing diagrams added (see below). Also TLP222G photo mosfets are available in the shop here. There has been discussion on Stompville here (in the comment section) and on diystompboxes.com about problems with audio clicks when using a relay for true bypass. The consensus seems to be that the answer is… Read More »