Switchable impedance & voltage

[glefty]

Apologies if this has been answered but I did a search & didn't find anything so here goes my 2 cents.
Q1. Can anyone explain why 99% of makers WON'T allow amps to be 100/120/220/240 volt switchable? Genz Benz auto detects & Eden has a switch & a few other makers do allow it but most don't: WHY? :eyebrow:
Q2. The same question about changeable impedance or ohmage, as on the Fender Bassman, Orange & even Epifani speaker cabs allow it, so why don't most makers?? Would this not cut down on the expense of having to produce different circuits etc?? :confused: Does tubes V solid state make a difference in this? Please educate me! I also posted this question on TB but as it is largely American, I figured most wouldn't really concern themselves with or even be aware of these issues as much as UK, EU, AU, NZ, SA & others outside North America. Cheers.

[Bill Fitzmaurice]

[quote name='glefty' timestamp='1337009823' post='1653916'] I also posted this question on TB but as it is largely American, I figured most wouldn't really concern themselves with or even be aware of these issues as much as UK, EU, AU, NZ, SA & others outside North America.
[/quote]And there's your answer. Manufacturers who do little distribution outside N. America aren't going to increase their build cost by using dual primary power transformers.

[LawrenceH]

Markbass amps are internally switchable, and probably quite a few others as well. The cynic in me thinks this is probably about limiting the number of people buying kit from countries where it's cheaper.

[dincz]

Don't know if this is true in the real world, but I'd expect switchable mains voltage to be more common in amps with switch mode power supplies. In any case, 100V - 250V voltage tolerance (without a switch) is not unusual in SMPS.

[flyfisher]

I'd be surprised if 99% of bass/guitar amp manufacturers don't allow some form of mains switching. Is that one of the 84.6% of statistics made up on the spot?

Globalisation is the driver for things like universal PSUs and IEC mains leads as it allows manufacturers to reduce their model variants and stock inventories, which are big advantages for any company selling into global markets.

dincz is right about SMPS; they usually have a 'universal' mains input.

[Musky]

Re the impedance switching thing, for SS amps it's pretty much a waste of time. They generally have a minimum load which is usually 4 ohms but sometimes 2 ohms. That pretty much covers most people's needs. Orange are the oddball here, in that the Bass Terror puts out 500w into either 4 or 8 ohms. Valve amps are a bit different in that the output impedance needs to be matched to the cabinet's impedance so they'll almost always have a switch - and although you cite the Bassman, the old ones actually only operated at 4 ohms!

The Epi uses a dual coil to switch impedance (there was definitely a thread here somewhere on this!) and quite frankly had more drawbacks than advantages - hence why nobody else takes this approach!

[glefty]

Thanks for the replies gents. I should have said user switchable or externally switchable in the original post. Of course quite a few allow voltage conversion internally is a workshop but still, if Genz, Eden, PJB & others allow for the 100-240 v option so simply, is that reflected in substantially higher prices? As flyfisher said re global markets, wouldn't it make sense, especially considering 240v Europe's 400 million people, 220v SE Asia's 300 million, 240v ANZ's 30 million & this dwarfs the NAmerican 330 million, so a very viable market for US companies I'd say. Point taken re user switchable ohmages for valve amps, cabs & SS heads but I'm still on the voltage switching soapbox; it just makes for better efficiency & economics as I see it. It was a deal maker for me to buy a GB combo & a GK head as well so it paid off for those companies & I'm sure I'm not the only one. YMMV.