.Talk with your fellow tone freaks on the web's liveliest (and friendliest!) tone forum. All are welcome, from seasoned pros to absolute beginners.If this is your first visit, be sure tocheck out the by clicking thelink above. You may have tobefore you can post: click the register link above to proceed. To start viewing messages,select the forum that you want to visit from the selection below.Tech experts from Seymour Duncan are regularly on this forum, and are clearly labeled as employees of Seymour Duncan. They are here to help. I'm a big fan of parallell wiring for one reason: if a speaker blows up, you still have one speaker working and your amp still sees a load (double of what it originally was) instead of seeing no load at all and risk taking the output transformer with it.Seconded.Given the choice I prefer parallel wiring in a 2x12 or 2X10 for this same reason & I think in some cases there's sonic benefits to doing it this way as well???I ran into a similar situation when I recently converted a old S.S. Princeton Chorus into a 2X10 cabinet for my modded Little Giant 5W Class A head.
The Princeton originally had two 8ohm drivers in it & that's what I bought when I was shopping for ALINCO replacements. So when it came time to wire it up I could either go with a 16ohm load in series or a 4ohm load in parallel. Since this cabinet was going to be used exclusively for the Little Giant, & since my Little Giant can be run at 4ohms, 8ohms, or 16ohms, I figured I'd try both options to see what I liked better.Now had I been looking for versatility (to be able to use it with my other amp heads) I'd have gone with a 16ohm load without question because as stated above a lot of modern amplifiers don't even give you the option to run them at 4ohms. However in the case of this little 5W head it seems to hit the speakers a little harder when going into the parallel wired 4ohm cabinet vs the series wired 16ohm cabinet.I suppose this could all just be in my head & it doesn't make a difference, but as Surgeon said it's nice to know that if I blow up a speaker there's another one in there to help spare my transformer??? I have found most heads sound best at their highest impedance offering. Is that just my tired old ears?
Phantom BS I've sold myself? I like two 8ohms wired as 16 for that matter.If one of the speakers blows, my transformers are solid enough to be okay while I walk over and turn off the amp.Leads to a question I've never asked, but how would a blown speaker completely cut off the circuit?
I have a Blackstar HT Club 50. I has speaker outs that allow for running one 8 ohm cabinet alone, two 16 ohm cabinets in parallel, or one 16 ohm cabinet alone. It specifically states “The output marked ‘1×16 Ohm’ should never be used at the same time as any of the outputs marked ‘1×8 Ohm or 2×16 Ohm’. Jun 09, 2010 To make sure I'm understanding you, you've got a head rated at 100 watts at a 4 ohm load, and you're looking to power two 8 ohm cabinets (rated for 300 watts each) with it. The amp will see a 4 ohm load, and you'll be putting 50 watts into each cabinet at max.
Wouldn't it just sound like crap?What I thought too, how likely it really is for a speaker to short out? Without starting to make concerning noises before.Also, some have said it in favor of series wiring, that if speaker goes out in middle of gig etc. When you might not notice one speaker going out parallel, you will notice it in series and won't run your amp on higher load. Though it definitely wouldn't be as bad as going a moment without any load.I really have no opinion about this matter, but I'm interested to hear others.
My amp's highest output is 8 Ohm and the only cab I have right now is a 2 x 12 wired in series (I think), which is additive making it 16 Ohm (again, I think - Correct me if I'm wrong).The manual for my amp says that the 8 Ohm output can be used with the 16 Ohm cab in what it calls a 'Safe Mismatch'.What qualities can I expect in the sound when using a 'Safe Mismatch' in this manner? The manual neglects to say what a 'Safe Mismatch' actually means and how it will affect the sound produced.As requested in some answers/comments:It's a Mesa Boogie Mark V:25, tube amp, with selectable 25 or 10 W output for each channel. A tube power amplifier (like the final stage in your Mark V) has to have an output transformer to lower the output impedance (the 'Ohms') to a level appropriate to drive a speaker. What does that mean? Well if you know what voltage and current and power are, then one way to look at impedance is how much of the power you are putting out is in voltage and how much is in current? That ratio is one interpretation of impedance.The ratio of voltage to current coming out of power tubes is relatively high. But you need lots of current to make a speaker move, so you have to trade some of that voltage in for more current.
That's what a transformer does. How much do you trade in?The answer to that question is chosen by the amp designer and is your amp's rated output impedance. That means your amp is designed to put out its rated power with a specific ratio of voltage to current. The amp will pretty much put out how much voltage it's putting out in any situation, and it's designed to put out a certain amount of current along with that. Designed meaning that if it is not allowed to put out all the current it can, then you won't get the full rated power, meaning your sound will be quieter and maybe less clear. However, if your amp is allowed to put out more current than it is supposed to, then bad things can happen.Current creates heat, more current is more heat, and too much heat can melt things. Like your output transformer.
If your transformer isn't the first to go, then there are plenty of components in the amp that can be melted or just destroyed in other ways by passing too much current.So you have to hold your amp back from running crazy with current. This is what a speaker's nominal load impedance number is meant to indicate. It's not a precise number, but it's good enough for making sure you're not letting your amp run away with itself and overheat.Here's the short short version: If your speaker cabinet's nominal load impedance is equal to or greater than your amp's rated output impedance, you will be safe. Safe at least in terms of not overheating your amp. If the speaker's impedance is higher, as stated before you won't get the rated output power and there may be some tonal changes. There are lots of interesting interactions between a speaker cabinet and an amplifier, so how the sound will change isn't so easy to predict, but if the speaker impedance is higher, you can safely experiment and found out how it sounds.One more thing to check is that the rated power dissipation of the speaker cabinet is greater than the rated output power of the amp. That way all the current coming out of the amp won't melt the speaker.If you ever get into live sound PAs, just know that it's a different world because those amps are not tube amps.
You still need to pay attention to power levels for sure, impedance not so much, and the rules of thumb will be different. But that's not relevant to your question.
I just didn't want you to think back to this years later and think you can set up your PA the same way as your Mark V. If they're 2x8 Ohm in series, then yes that would give 16 - but guessing is no good.3 ways to find out, check the maker's plate on the back, get a multimeter & test it, or take the back off & look.For an annoyingly under-technical explanation, read on.The reason 16 is 'safe' is that amps have a tolerance; 8 - 16 is pretty standard. Some can work down at 4 Ohms & a very few at 2. Running an amp into too low impedance will suck it dry (not a technical term;-) & kill it pretty quickly at high volumes, through overheating.Running into too high an impedance would really start to impact your output volume & eventually overload a valve amp's power stage.If you really want brain-hurting detail, see. 16 ohm speakers are unlikely to be a problem.
The term 'safe mismatch' is really a misnomer. Amplifiers are not 'matched' to the speakers. The amplifier output impedance is normally very low. But the amplifier has voltage, current and power limits that should not be exceeded. Additionally, valve amplifiers don't like very high impedance loads as stray inductance in the output transformer can result in very high voltages being generated. These can cause flash-over in the output tubes and/or breakdown of the output transformer insulation.Your 16 ohm speakers will have one quite predictable effect - if the amplifier is rated at say 100W into 8 ohms, it will only deliver approximately 50W into 16 ohms.
I am not a technical savy person per say! But through experience I know that running a 16ohm speaker with a Tube Amp rated at 8ohm will not blow up your amp, only thing I have noticed is volume difference, earlier breakup of the tubes, and some noise! I have run them mismatched for years with no real technical issues with transformers, or any other component other than Tubes! The Tubes really take the blunt end of it all, they may run a little hotter than normal! But in all my years of playing and experimenting with amps and cabs, I have never had an issue!
Personally, I would never trust a 'Safe Mismatch'.