The Baldwin-Burns Buzzaround Fuzz Pedal. |
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Click image for schematic pdf.
The original circuit, most typical component values. This is interesting because in one small circuit we have something which both compensates for and also relies upon the poor quality of the transistors available at the time.The first stage is a simple linear amplifier, and uses two transistors to ensure an adequate composite hFE and a good overall voltage gain. The second stage will not work properly unless the transistor has some amount of leakage. Unless there is leakage from the collector-base junction, it can cut the signal completely when it falls below 0.5V p-p. This leads to an effect often referred to as "velcro-sound" or "gating". |
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Click image for schematic pdf. My version of the Buzzaround arranged for negative ground. The first linear two-transistor stage is replaced by a single modern silicon NPN transistor. Two transistors are unnecessary for a simple CE amp of this sort, and we get less noise and other problems. The second stage can be either a silicon or germanium NPN transistor. The easiest way to get a good sound, which will be very close to the original circuit, is to find an old NPN germanium transistor with a little leakage for Q2. Using a silicon transistor will generally get better results in the quality of the sound compared to the original, and have less noise and temperature dependence. But it will likely have the velcro-sound and gating effect if you can't find one that is a little leaky. However, with modern transistors, any leakiness is often linked to other defects, such as weird noises and unreliability. The usual way to get around this problem seems to be to use a resistor from base to collector to simulate leakage. I have seen values around 470k recommended. In my experiments I have found a 39k or 47k works well. Doing it this way results in a more reliable and usable fuzzbox than the original. |
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A PCB for DIY construction. Suitable for pots mounted on or off the board. It has positions for a pull-down resistor to avoid clicks with full-bypass switching, and an LED indicator. Price £6.50 with free p&p in UK. £3.50 P&P for ROW. Helpful notes and diagrams included with each order. A fairly easy project. |
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Built with a BC182 for Q1 and an anonymous old NPN germanium transistor for Q2 and an OA81 germanium diode. Pots mounted on board. The LED is mounted so that it sticks out the back of the PCB. |
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Sounds and behaves near exactly like the old Buzzaround in the pictures below. |
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This one is built using a BC184 for Q1 and a BC109 for Q2 and a 1N4148 for D1. Some of the resistors and capacitors are different from the schematic, they are just what was nearby. Experiments with different value components generally have fairly predictable results, for example larger input and output capacitors let more low frequencies through, and varying the bias point of Q1 can get some even more extreme distortion. |
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As expected, it has the gating effect, so I put a 39k resistor from base-collector of Q2 which you can see on the back of the board. |
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Turned out to be really good, it was sold half an hour after I got it finished. |
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A well-used Buzzaround, repaired a few times over the years but still mostly original and sounding fantastic. |
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I have read on the interweb that only around 200 of these were made. Maybe this means number 141 made in 1967? |
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Frequently Asked Questions |
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1) If I buy one of your boards and follow the schematic will I get something like an original Buzzaround? (Stephen, Cambridge) Like it, but should be better. They varied a lot and were often noisy and unreliable. 2) It looks like you don't follow your own schematic, and you just stuff any old component in regardless. (Henry, Oxford) Yes, and you are quite welcome to do likewise, Henry. If you think you're hard enough. 3) So what transistor is best to use for Q2? (Paul, Nottingham) I really don't think it matters much, so long as it's not faulty. The easiest is if you can find an old NPN germanium transistor. The best sound comes from a silicon transistor with a leak resistor as described above. Changing the diode D1 from silicon to germanium makes a slight difference, much less than you would expect. Make sure you get the legs in the right holes. 4) What sort of box is that? (Stephen, Cambridge) It is a diecast metal box, usually referred to as a 1590BB. If you Google or look on ebay you will find lots of them. 5) it got a led in it i don fink u shud ave a led in it cuz leds is niosy an that innit? (Stan, Colchester) What is it with you and the LEDs, Stan? Did a LED mug your granny or something? The LED isn't really in the circuit. 6) What does it sound like? (Paul, Nottingham) Fuzzy. 7) You seem to be saying that a silicon version will sound better than a germanium one, but it's more trouble because it needs an extra resistor selected and added. A lot of people are saying germanium sounds better. (Paul, Nottingham) Yes. 8) I don't think you have studied the market. You don't seem to know that there are exact clones available, also kits and parts that can be used to build an exact clone. (Henry, Oxford) Yeah... good luck with that. 9) I put it together correctly and it doesn't work. (Timothy, Newcastle) No you didn't. |