Advice needed about Marshall Cabs!?

I have recently bought a 100watt Peavey Valveking head but don't like the tone of it through the peavey cab that you're 'supposed' to use with it. I tried it out with a Marshall cab and it sounded much warmer and rounded but I want to clarify details on which cab I should get and how to set the ohms on the amp and cab so that I won't fry anything!





I think I am going to buy the Marshall MG412 angled cab. Would this be suitable for this amp? Thanks.Advice needed about Marshall Cabs!?
Stock cabs, like stock pickups, tend to kinda blow. I prefer to experiment with different cabs and go with the one I like best! Different speakers bring out different tonal characteristics, and good speakers actually help improve your tone!





The Marshal MG412 is okay, but there are better ones out there, imho. Of course, not everyone can drop 600$+ for a cab, though! I really like the 1960a cabs... the Celestion G12T-75's are one of the best speakers for rock, in my opinion - the high wattage rating keeps them from breaking up, they have a lot of clarity, and not so much treble that they sound hissy.





If you have a couple hundred dollars, I urge you to check out avatar speakers (I think that's the right link below... from memory... google if I'm wrong!). They make custom cabs that are in general far better than the ones you can buy, on a dollar for dollar basis.





You also might want to consider just replacing the speakers, although admittedly this can be just as expensive and you kinda have to know what you're doing. A good, and relatively inexpensive, site is listed below.





There is a bit of misinformation or ignorance about how to correctly hook up a tube amp to a cab out there, but I'll try to explain the guidelines as I understand them.





The simplest rule is to match impedances. If the cab has an 8 ohm impedance, use the 8 ohm out on your amp. Its that easy - matching impedances gives you the maximum possible transfer of power between your amp and your speakers.





The safest thing is that if you aren't sure, then to go from a low impedance out to a higher impedance cab. In other words, if you only have an 8 ohm out but a 16 ohm cab, then that is safe.





This is an impedance thing - going into a higher impedance reduces the energy transferred a little (so slightly lower volume, barely perceptible in my experience), but gives you a little more higher frequency response, ie, it should brighten things up a little.





Technical stuff: the reason why passive pickups have tone sucking issues is partly because of cable capacitance, but a lot of it has to do with impedance. Going into a higher impedance (10x higher is the standard) in audio terms means you keep all of your voltage, although you lose current. When talking audio signals, though, you don't count current, since DC is blocked by capacitors in your audio circuits anyways. Soooo.... going into a higher impedance means you lose some power transfer, but you lose a little less voltage, and that means higher signal fidelity. This can be good or bad, honestly, it depends on your rig and your speakers. Many amps/tubes like to be pushed a little harder, so a little more impedance isn't a big issue.





The disadvantage of this is that it puts more resistance on your power tubes (the output transformer and the power tubes have to dissipate a little more heat). If your tubes are low-quality, this *may* reduce their lifespan a little. It shouldn't, but to err on the side of caution it is best to use good quality power tubes and to always keep a backup set on hand.





On the other hand, it is more stressful on your amp to go into a *lower* impedance. This means the amp will deliver less voltage but more current, and this can *definitely* place a toll on the power tubes and output transformer. I do not recommend this - sure, most amps are designed well enough to handle this type of load, but to be on the safe side, higher impedances are okay, lower impedances are not, matching impedances are ';standard';.





Briefly, about impedances - speaker impedance is kinda like an ';average';. Some frequencies will have higher impedances then others, and that's what creates the frequency response! So at some frequencies the amp will see hundreds of ohms, at others only a few... something to keep in mind....





One of the most important things for tube amps, in my opinion, is to use your standby switch! Flip it onto standby for at least 30 sec (60-90 is better) so the tubes have a chance to warm up before you turn your power on. Likewise for powering down - go to standby for at least 30 seconds before you turn it all the way off. This babies the tubes, and helps them last longer. Beyond that, if you walk away from your amp and don't plan on using it for at least 10-15 minutes, then put it on standby.





I love the standby switch - I've accidentally left my Mesa Tremoverb on standby overnight, but its not really an issue - the tubes are getting less power and aren't really doing any work, so it doesn't hurt them.





The most, most, most important thing is to never turn your amp on without it being plugged in to a speaker!!! This places a *huge* strain on them, and can easily damage both them and the output transformer.








Hmm. I think I've gone on long enough. Good luck!








Saul