After recently stumbling onto this article I have been looking for Panasonic heavy duty (black and blue) 9 volts for my fuzz pedals. Does anyone know where these are still available and if this article still remains relevant? I'm guessing these remain in production and still are carbon batteries? http://www.guitarplayer.com/article/stompbox-stampede/jan-00/4924 http://www.guitarplayer.com/article/stompbox-stampede/jan-00/6764 Assault and battery. Some players and stompbox makers swear that battery type affects the sound of their pedals. Highly possible -- a 9-volt battery is actually a stack of six 1.5-volt cells, and the quality of the connections between those cells can make a difference in the source impedance of the voltage, which may affect the sound of a device. Also, the two most popular battery types -- alkaline and carbon/zinc -- have unique qualities. Alkalines last longer and their output remains steadier under load, whereas carbon batteries sag noticeably under load but often yield superior stompbox tone. We tested a small control group of Ibanez Tube Screamers with various brands of 9-volt batteries and found that they did indeed sound louder and crisper when administered higher doses of carbon-generated electrons. People practically go into convulsions over Eric Johnson's reported ability to hear battery-induced differences in his pedals, but it's not that far out. Batteries do differ: Duracells pump out 9.5 volts, but they're not the strongest cells in town. Among the hottest batteries we found were the Taiwanese Magicell (William Electric & Battery Co.) and Ray-O-Vac Heavy Duty Maximum (carbon) at 9.7 volts and the Hong Kong-made Hi-Watt Super Heavy Duty and Panasonic Heavy Duty (carbon) at a tongue-zappin' 9.8 volts. The Maxon carbon battery that Ibanez issues with their new effects measures 9.6 volts, a Radio Shack Enercell carbon battery is good for 9.3 volts, the Eveready Super Heavy Duty delivered 9.4 volts, and an alkaline Eveready Energizer yielded 9.3 volts. Experiment and listen. We couldn't test everything with multiple batteries. Even though many of the older effects were designed in the carbon-battery era, for consistency's sake we installed fresh 9-volt Mallory Duracell alkalines in everything we tested. All voltage measurements were done with a B&K Precision 815 digital parts tester, which provides a 15-milliamp load specifically for testing 9-volt batteries.