8ohm speaker in 4ohm fender reverb amp? i know its overdone but lets hear it

I have a fender silverface pro reverb and am looking to put some big old jbl's in it. either an e120 or k120. These speakers are rated at 8ohms but actually measure around 6.2ohms in general. I know its not that bad for the amp to use a little bit higher speaker impedance than called for, in these old fenders at least. and i know its harder on the power tubes, but some people actually really like the sound of the pushed tubes... most people that have tried this actually- from my experience. I know there are some posts online that adamantly disagree... saying transformers will blow out and only lower impedance is okay- that is regarding transistor based amps- not tube based- at least that's what many pro's have said on the subject- i think the crazy ass Lord Valve disagrees with me here too- but he is nuts- and i know- i used to live in denver i know

Anyways, about how much harder is this on the tubes? will it take away 10% of their life? 20%? anyone know? I bias around 60-65% so I'm not too hard already. Using one of these speakers would save my back and my need to get an external cab and turn my vintage fender into a head unit, save money etc. so replacing tubes 3 times a year instead of twice for a bit better tone and lighter weight is exactly what i'm looking for!

Thanks!

6.8 is the DC resistance, the impedance would be rated as 8 ohms but it varies with frequency. I would not worry about running it with 8 ohms, if your bias is not out of whack the plates actually will dissipate less and the screens a little more. Use a set of tubes and see how long they last. The tubes may not care that much.

anyone ever tried this and had tubes just get burnt up? I'm thinking I'll give it a go

I have a fender silverface pro reverb and am looking to put some big old jbl's in it. either an e120 or k120. These speakers are rated at 8ohms but actually measure around 6.2ohms in general. I know its not that bad for the amp to use a little bit higher speaker impedance than called for, in these old fenders at least. and i know its harder on the power tubes, but some people actually really like the sound of the pushed tubes... most people that have tried this actually- from my experience. I know there are some posts online that adamantly disagree... saying transformers will blow out and only lower impedance is okay- that is regarding transistor based amps- not tube based- at least that's what many pro's have said on the subject- i think the crazy ass Lord Valve disagrees with me here too- but he is nuts- and i know- i used to live in denver i know


On the contrary, with SS amps, any impedance above the rated one is fine, just drops power, but absolutely no danger for the amp itself.
With tubes, you should always match the impedance, and a higher one is what is dangerous.
Anyway, speaker impedance is only a rounded value at medium frequencies, and most speakers have a DC resistance lower than the actual impedance at say 1Khz.

A higher impedance is a danger for two reasons. You get greater screen current, really a concern if you do not have resistors on the screens but even back in the day when this amp was built they were included. The other thing is the transformer converts a magnetic flux into a voltage and corresponding current in the secondary circuit. Basically you get so many V (volts) and A's (amps) for the amount of magnetic flux in the transformer core. The lower the impedance of the speaker the lower the V but higher the A. The higher the speaker impedance, the lower the A but higher the V.

With no load on the transformer the voltage can go very high, enough to punch though the wire insulation which then causes a short. Doubling the rated speaker load on a Fender should not cause this to happen, the output transformers usually can take a 100% mismatch in the load.

Don't do it. There was a recent thread about this very thing. It can mess things up, very enlightening posts there. I had no idea, but apparently it can do damage.

To put it simply,the resistance of a speaker is a part of the impedance so the impedance will always be a bit bigger than the resistance.

I have a fender silverface pro reverb and am looking to put some big old jbl's in it. either an e120 or k120. These speakers are rated at 8ohms but actually measure around 6.2ohms in general. I know its not that bad for the amp to use a little bit higher speaker impedance than called for, in these old fenders at least. and i know its harder on the power tubes, but some people actually really like the sound of the pushed tubes... most people that have tried this actually- from my experience. I know there are some posts online that adamantly disagree... saying transformers will blow out and only lower impedance is okay- that is regarding transistor based amps- not tube based- at least that's what many pro's have said on the subject- i think the crazy ass Lord Valve disagrees with me here too- but he is nuts- and i know- i used to live in denver i know

Anyways, about how much harder is this on the tubes? will it take away 10% of their life? 20%? anyone know? I bias around 60-65% so I'm not too hard already. Using one of these speakers would save my back and my need to get an external cab and turn my vintage fender into a head unit, save money etc. so replacing tubes 3 times a year instead of twice for a bit better tone and lighter weight is exactly what i'm looking for!

Thanks!

That model Fender uses TWO 12" 8Ohm speakers wired in parallel to give a 4 ohm load at the output transformer. What you're proposing won't change the the load the amp sees at all.

That model Fender uses TWO 12" 8Ohm speakers wired in parallel to give a 4 ohm load at the output transformer. What you're proposing won't change the the load the amp sees at all.

I thought he wanted to run one 8 ohm speaker.

Oh no not again

DC resistance of an 8ohm impedance speaker is 6ohm.

Problem is that the 8ohm is measured at 400Hz, this is roughly G 3rd fret 1st string, most of the guitar's notes are below that and the speaker's impedance rises to 50ohm at its resonance frequency around 80Hz, bottom E open 6th.

This means a guitar amp is always mismatched. A guitar amp is built tough and can handle this.
But you cannot go under the specified load with a valve amp.
A 50% overload is acceptable.
A 100% overload is the limit, and must not be cranked up.

This amp is designed for a 4ohm load., doubling its load will not do it any favours.

for all the naysayers saying you absolutely cannot go up- SRV ran a 2ohm transformer with an 8 ohm speaker load in some of his amps. and he cranked them up. but of course diaz himself would change the tubes midshow with oven mitts.

and yes it's one 8 ohm speaker with a 4ohm transformer. sorry i should have been more clear

This is definitely a popular thing to do, on purpose, for a particular effect. and I am absolutely positive it wont kill MY amp... being a vintage fender. this is not a modern production crate or an amp that cant take some abuse. Tons of people do this, on purpose, for the effect.

I'm really not interested in the naysaying unless you actually have personal experience- not someone that brought you an amp that said this was broken and this is why.

I'm really looking for people that do this or have done this and know what the effect on tube life is, if any.

Thanks for the posts so far guys. and jefrs would 50% be a 4ohm tranny with a 6ohm load and 100% be a 4ohm 8ohm deal?

First your load is NOT 6 ohms, but a normalized 8 one, and can be 25 omhs at 5 Khz !
Your tubes see about 440 volts static, about 600 dynamically ; if you double the load at the secondary, you double the load on the primary, quess what happens to the dynamic voltage ?
Cesar Diaz said he replaced the super reverb OT with Twin one's....but i've never read a single word from him about a 400% mismatch.
Anyway, you can probably play with a 100% mismatch with no risk, impedance ratios are not that precise, nor as said before the Speaker impedance, which varies with frequency, the OT's impedance ratio is choosen to give the amp the more power for a given B+ and that's all.
But you cannot say it's good practice or has no importance at all.

http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#matchspkr

You could install catch diodes on the primary of the output transformer. Amp manufactures tend to use them now days. They clamp the inductive back EMF so that the voltage does not get over 2X the supply voltage protecting the transformer, sockets and tubes from breakdown. In the Hotrod it is CR4-5, R3000, Fender PN 029690001.

http://ampwares.com/schematics/hotrod_deluxe.pdf

Clay, first thought....matched speaker load/OT is prefereable and sounds better than either a 50% lower load or a 100% higher load. I am not goingt o get into what oen or the other of thesemismatches will/might do to the OT and circuit. I am going to say that Fender allowed for the 50% mismatch ....so they weren't afraid that their amps couldn't handle that. And...I know of 4 ohm OT's that have run an 8 ohm load...1X15" in a TR....for decadse. NOte: that player is a country player andnot a push it to the limit rocker.

Re: SRV and his 1X15" Vibroverbs that Diaz modded. It is true that Diaz installed Twin REverb, 4 ohm OT's in those amps for SRv. However, when running 2 X 6L6's through that 4 ohm OT wiht an 8 ohm load, the whole equation is actually a 'match'. REmember,when one pulls two 6L6's out of a TR to lower the output, one can maintain the match ofimpedance requirement v. load by discsonnecting one speaker to put an 8 ohm load on there...for a match.

ADN....Diaz installed that OT in order to increase power an stiffen up the output section...more punch, less saturation in comparison to that little Vibroverb OT. HE knew what he was doing in the 'matching impedances' department. HE coudl have put in a bAssman OT for the increase inpower and stiffness....but he would have had a mismatch, right? 4 ohm OT and 2 x 6L6's with an 8 ohm load. HE chose to mod to a matched situation. that right there is a lesson in matching and mismatching form someone whounderstaood the situation very well, I would think.

I had read this... then I realized it was an article about SRV's amp... that was supposedly bought... but they failed to include pictures of it...

http://www.valcoamp.com/page/srvs-final-notes-a-harsch

you can skip down

Okay, Clay...I stand in error. My memory is not what it used to be. Here is the quote from the interview with Cesar Diaz in the August 2000 issue of teh Tone Quest/ Vol. 1 No. 10....page 5.

"We also chagned the output transformers on the Super REverbs to those from a TWin Reverb, and on Vibroverbs we used output transformers from a Bassman."

So, that seems to be a mismatch on the SR's whiel the Vibroverb is 'matched' with that 4 ohm OT and the 8 ohm load workign with two 6L6's, right?

Diaz goes on to say: "I'm not such a stickler on matching impedance becase Fenders are very tolerant amps. You just about feed them anything."

Hmmm.....I find the SR situation with the 2 ohm load on a 4 ohm OT with two 6L6's to be interesting. He matched 100% to the lower side, right? 2 ohms speaker load against what is in effect an OT/power tube combination that is looking for an 8 ohm load....in a technically ideal situation. That supporst his 'feed 'em anything' thought, right? That might also support jefrs contention that the fEnder OT's were actually built for half of the specified load?????? IF that is true, then running a 2 ohm speaker load against that 4 ohm OT with only 2 X 6L6's is a 50% mismatch.
IF this 'half of spec' thing is so, then that 8 ohm 1X15" in that TR that I know of has been running 200% moreload than the OT was spec'd for....and doing it long time, right? Which also supports Diaz's 'feed 'em anything'. ?????

Whatever floats the boat, imho...but I like a match. I bet that those amps got frequent routine general service, though....just to make sure everything was what it should be.

for all the naysayers saying you absolutely cannot go up- SRV ran a 2ohm transformer with an 8 ohm speaker load in some of his amps. and he cranked them up. but of course diaz himself would change the tubes midshow with oven mitts.

and yes it's one 8 ohm speaker with a 4ohm transformer. sorry i should have been more clear

This is definitely a popular thing to do, on purpose, for a particular effect. and I am absolutely positive it wont kill MY amp... being a vintage fender. this is not a modern production crate or an amp that cant take some abuse. Tons of people do this, on purpose, for the effect.

I'm really not interested in the naysaying unless you actually have personal experience- not someone that brought you an amp that said this was broken and this is why.

I'm really looking for people that do this or have done this and know what the effect on tube life is, if any.

Thanks for the posts so far guys. and jefrs would 50% be a 4ohm tranny with a 6ohm load and 100% be a 4ohm 8ohm deal?

I've been running my '74 Deluxe Reverb that has a 4-ohm OT into a single 8-ohm speaker for the last two months, playing lound (master at "10", gain at 7) for a couple hours at a time and the tubes (old GE's) sound good still (as of yesterday.)

for all the naysayers saying you absolutely cannot go up- SRV ran a 2ohm transformer with an 8 ohm speaker load in some of his amps. and he cranked them up. but of course diaz himself would change the tubes midshow with oven mitts.

and yes it's one 8 ohm speaker with a 4ohm transformer. sorry i should have been more clear

This is definitely a popular thing to do, on purpose, for a particular effect. and I am absolutely positive it wont kill MY amp... being a vintage fender. this is not a modern production crate or an amp that cant take some abuse. Tons of people do this, on purpose, for the effect.

I'm really not interested in the naysaying unless you actually have personal experience- not someone that brought you an amp that said this was broken and this is why.

I'm really looking for people that do this or have done this and know what the effect on tube life is, if any.

Thanks for the posts so far guys. and jefrs would 50% be a 4ohm tranny with a 6ohm load and 100% be a 4ohm 8ohm deal?

A 6ohm impedance is nominally 3x8ohm speakers (2-series & 1-parallel to 5.333ohm) and is a +50% load

An 8ohm load on a 4ohm tap is a +100% load, which is fine if you don't mind risk of blowing the output valves and/or the OT cooking - the the OT will get hot enough to fry an egg with the correct load. Remember that 8ohm load is actually somewhere between 50ohm and 8ohm.

And as you have a vintage Fender, its OT is actually wanting a 2ohm load [ref Gerald Weber, Hip Vintage Valve Amps...], it can run 2ohm and 4ohm, and maybe a little over. With a 4ohm speaker it is already running at +100%, it is designed to drop to 2ohm when you add a 4ohm ext cab in parallel, this does provide a little more power.

If you want to do it properly then run two 8ohm speakers in parallel, which is a 4ohm load.

What happens when the load goes wrong? - I had an AC15 blow the speaker (G12-15) which shorted and caught fire, which caused a fly-back on the OT, I got an electric shock which knocked me on my back, meantime the main fuse blew and all the lights went out, the girls started screaming as the boys started a fight.

An 8ohm load on a 4ohm tap is a +100% load, which is fine if you don't mind risk of blowing the output valves and/or the OT cooking - the the OT will get hot enough to fry an egg with the correct load. Remember that 8ohm load is actually somewhere between 50ohm and 8ohm.

You know I hate questioning you on some of your posts but either I miss the logic or there is not enough info for me to process the information so I hope you do not mind my asking a few questions.

So I take it an 8 ohm load will cause a transformer to get hotter than if it is feeding a 4 ohm load that it was designed for. How does that happen? Let's take a case of a short circuit across the transformer output. Not much voltage but a lot of current. And since the only real resistance (although we are dealing with AC the correct term is impedance but since those less technically confident have an easier time with resistance we will use it) is due to the output winding, the voltage drop occurs across the winding and since the current is equal in the whole circuit the power is dissipated in the transformer (Power = Volts x Amps).

Now the other extreme is if the transformer is lightly loaded. we will get a higher voltage but a lower current in the secondary. Given that the current is equal in the secondary loop and that there is more of a voltage drop in the load rather than in the secondary winding I would think we would assume that most of the power will be dissipated outside the transformer. In my neck of the woods this would cause the transformer to run cooler.

Now if you chart the amount of power dissipated in a transformer, with a dead short as all the heat developing inside the transformer and with the transformer lightly loaded with most of the power turned to heat outside the transformer, you might take it with a leap of faith that driving a four ohm load will heat the transformer up more than driving an eight ohm load.

Or you might not. I am scratching my head on this one.


What happens when the load goes wrong? - I had an AC15 blow the speaker (G12-15) which shorted and caught fire, which caused a fly-back on the OT, I got an electric shock which knocked me on my back, meantime the main fuse blew and all the lights went out, the girls started screaming as the boys started a fight.

Actually I think the speaker shorting would load down the transformer. Maybe the speaker opened after the short and then the transformer ha no where to loose the energy resulting in the fly-back?

An OT getting hot is normal. Try putting your hand on it after using your amp hard.

Simplified - the amp will try to push the same current into the increased load, which means it will have to provide an increased voltage. The OT gets punished. The output valves take a pasting.

Take a look at some valve charts, they and the data sheets will provide some optimum load value. This is the load of the primary. The actual resistance of the primary and secondary winding is very little. To obtain the correct load we multiply the speaker impedance by the turns ratio i.e. rearrange for resistance Vin/Vout = Iin/Iout = n where n is the turns ratio
Rprimary/Rsecondary = n^2 the transformer changes resistance by the square of the turns ratio.

Example
A turns ratio of 31.6:1 would allow the output valves to see an 8ohm speaker as an 8kohm load,

- whereas the speaker sees the Thévenin output resistance of the output valves stepped down by an identical amount (the latter is an important distinction between valve and solid-state and goes some way to explain why valve amps are louder for the same power output)

If you were to double this example 8ohm speaker to 16ohm, you do not increase the load on the valves by 8ohm but by 8kohm!

And which is why small changes in speaker load have a big affect on the valve amp.

A 6ohm impedance is nominally 3x8ohm speakers (2-series & 1-parallel to 5.333ohm) and is a +50% load

An 8ohm load on a 4ohm tap is a +100% load, which is fine if you don't mind risk of blowing the output valves and/or the OT cooking - the the OT will get hot enough to fry an egg with the correct load. Remember that 8ohm load is actually somewhere between 50ohm and 8ohm.

And as you have a vintage Fender, its OT is actually wanting a 2ohm load [ref Gerald Weber, Hip Vintage Valve Amps...], it can run 2ohm and 4ohm, and maybe a little over. With a 4ohm speaker it is already running at +100%, it is designed to drop to 2ohm when you add a 4ohm ext cab in parallel, this does provide a little more power.

If you want to do it properly then run two 8ohm speakers in parallel, which is a 4ohm load.

What happens when the load goes wrong? - I had an AC15 blow the speaker (G12-15) which shorted and caught fire, which caused a fly-back on the OT, I got an electric shock which knocked me on my back, meantime the main fuse blew and all the lights went out, the girls started screaming as the boys started a fight.

you say I should get two 8 ohms in parallel, but what you just said states taht I should really get 2 4ohms in parallel, because my amp actually wants to see a 2ohm load... even though it clearly states on the back of the amp, between the speaker and ext. speaker jacks. "Total Load 4 ohms"

Now, I'm not saying that they arent really wanting 2ohms... but you seem to be a guy that wants to give the transformer exactly what it wants. so if gerald weber says the amp really wants to see 2ohms, why not tell me I should put two 4ohm speakers in parallel?

An OT getting hot is normal. Try putting your hand on it after using your amp hard.

Simplified - the amp will try to push the same current into the increased load, which means it will have to provide an increased voltage. The OT gets punished. The output valves take a pasting.

Take a look at some valve charts, they and the data sheets will provide some optimum load value. This is the load of the primary. The actual resistance of the primary and secondary winding is very little. To obtain the correct load we multiply the speaker impedance by the turns ratio i.e. rearrange for resistance Vin/Vout = Iin/Iout = n where n is the turns ratio
Rprimary/Rsecondary = n^2 the transformer changes resistance by the square of the turns ratio.

Example
A turns ratio of 31.6:1 would allow the output valves to see an 8ohm speaker as an 8kohm load,

- whereas the speaker sees the Thévenin output resistance of the output valves stepped down by an identical amount (the latter is an important distinction between valve and solid-state and goes some way to explain why valve amps are louder for the same power output)

If you were to double this example 8ohm speaker to 16ohm, you do not increase the load on the valves by 8ohm but by 8kohm!

And which is why small changes in speaker load have a big affect on the valve amp.

You seem to be missing something so I will spell it out as clear as I can.



16 ohms is less of a load than 8 ohms.


Heat is the product of ( I² × R ) = Power (Watts)

The heat in a transformer is from magnetic losses and resistive heating of the wire. With less of a load on the secondary the less current flowing. 16 oms is less of a load than 8 ohms. The lower the number the less resistance to the current. The current increases in the secondary with less ohms on the secondary. Really. Ask your engineer buddies.


And I am not just making this stuff up. Just did a quick little experiment with a tube amp I have on the bench right now. Set up the signal generator to put out 200Hz. Put an 8 ohm speaker on the amp. I got 2.7V at the output. Put another 8 ohm speaker in parallel with it. The voltage dropped to 1.8V. I put them both in series to get 16 ohms (and I did check that they were 8 ohm speakers) and I got 4.0V.

Now to make it easy on you, here are the numbers.

4 ohm - 1.8V x 0.45A = 0.81W
8 ohm - 2.6v x 0.34A = 0.91W
16 ohm - 4.0v x 0.25A = 1.0W

So I had the amp set to a set level and the output transformer tried to deliver the amount of Volt-Amps (VA) that the tubes were supplying. The amp output roughly the same power but the voltage went up with less load (a bigger number in ohms) and the current went down. As you can see, the more current that flows the less power gets delivered out to the speaker. Could be the power curve of the tube but my money is on the IR loss in the secondary.

If there was no load (open circuit on the output) the voltage would even go higher but no current will flow. The transformer will not be passing any power and since there will be no IR losses (other than the primary) the amp will cool down. Just because I am a nice guy and I wanted to let experience do the talking rather than just asking people to take my word on it I disconnected the speaker while the amp was putting out this measly amount of power. The voltage on the secondary jumped up to six volts. So on a transformer that I consider to have a 8 ohm rating with the circuit I was using went from roughly 2.7V with an 8 ohm load up to 6V with no load.

Now what does this tell us? Not sure about others but to me it says that a lightly loaded transformer (a load with higher ohms) is easier on the transformer in terms of heat generation because of the drop in current but the voltage it runs at is higher. Now since the voltage on the secondary is higher it just makes a lot of sense to assume any back EMF from the speaker will get transformed by the primary to secondary ratio and be higher than normal if we run a higher speaker impedance. As long as this voltage when added to the supply voltage is less than the breakdown voltage of the main parts of the power stage all is good. If it is higher than the breakdown voltage...

I'm interested in hearing more about the bass loss and other tone differences I will have running an 8ohm speaker with my 4ohm amp. I'm not smart enough to realize how all this science, though I do appreciate what you all are doing. I'm curious as to how this stuff will affect the tone coming out of my amp. Loss of low end was mentioned- and I believe loss of high end was as well... Is this subtle or obvious tone changes? are we talking about measured dB's of high end roll or low end roll off?

Thanks for everything so far.

I'm interested in hearing more about the bass loss and other tone differences I will have running an 8ohm speaker with my 4ohm amp. I'm not smart enough to realize how all this science, though I do appreciate what you all are doing. I'm curious as to how this stuff will affect the tone coming out of my amp. Loss of low end was mentioned- and I believe loss of high end was as well... Is this subtle or obvious tone changes? are we talking about measured dB's of high end roll or low end roll off?

Thanks for everything so far.

I doubt there will be much of a difference between the same model of speaker with only having a difference in impedance, at least between 4 and 8 ohms or 8 and 16 ohms. Between 4 and 16, maybe, maybe not. As far as one impedance giving less bandwidth as compared to the other in the amp, the change in impedance should not change anything to the point where we would hear it. Even the cheap little amp that I used for the tests rolled off below 60Hz and above 12kHz. I would say an output section of a tube amp can put out more frequency range than we ask of it.

I'm not sure, there's a huge difference in my VHT with 6L6 between the bias intended for 6V6 vs proper bias for 6L6 and mismatch load -intended for 6V6- and a good one for 6L6 ; i suppose i should try with 6V6, will tomorrow.
Anyway, a loss of lows is not always obvious, it is in my amps as i tend to modify them for just the right amount of lows -so the smallest difference is hearable- but in a regular (not hi-gain) amp, there's not much shaping of the lows, so it would probably not make a difference, or only a slight one.

That's just brilliant Printer2, you have successfully proven that a higher load draws more power from the amp for the same input. Which is what I said - the volts go up.

But it is not supposed to do that, it doesn't do it any good.

Transformers conserve power so Pin = Pout.
Now OT are pretty tough but going from 8ohm load to 16ohm load (on the same secondary winding) does double the load on the valves, and which can take them over their operating boundaries (look at the graph on the data sheet).
The valves might want something like 5000ohm load, giving them 10000ohm load is going to be quite unpleasant for them.

try Morgan Jones "Valve Amplifiers" ISBN 978-0-7506-5694-8 pp27-28
[typo on p.28 should read Rprimary/Rsecondary = (Vprimary/Vsecondary)^2 = n^2 ]

That's just brilliant Printer2, you have successfully proven that a higher load draws more power from the amp for the same input. Which is what I said - the volts go up.

Excuse me? The power is effectively the same, 1 watt. I would not put too much into the difference in readings, especially when there is a bit of hum a scope reading between 2.6v and 2.7v could be thought of as the same reading. My money is still on the secondary winding impedance although the plate characteristics of the tube may have something to do with it.

Simplified - the amp will try to push the same current into the increased load, which means it will have to provide an increased voltage. The OT gets punished. The output valves take a pasting.

Well you got the voltage part right. The load is halved (ohms went up from 8 to 16) and the current is cut in half. And no the transformer does not get punished any more than with half the impedance and neither do the valves. What is your definition of being punished? Yours seems to be overheated although you do not seem to understand the mechanism that generates the heat.



Transformers conserve power so Pin = Pout.
Now OT are pretty tough but going from 8ohm load to 16ohm load (on the same secondary winding) does double the load on the valves, and which can take them over their operating boundaries (look at the graph on the data sheet).
The valves might want something like 5000ohm load, giving them 10000ohm load is going to be quite unpleasant for them.

try Morgan Jones "Valve Amplifiers" ISBN 978-0-7506-5694-8 pp27-28
[typo on p.28 should read Rprimary/Rsecondary = (Vprimary/Vsecondary)^2 = n^2 ]

Do yourself a favor before you post any more on what is a greater load and review Ohm's law. A light 60 watt light bulb over here (120vac) draws 0.5A due to its 120 ohm resistance. A 800 watt electric heater draws a bit over 6.6A. The light bulb has a resistance of 240 ohms while the heater has a resistance of about 18 ohms. The 18 ohm load is a greater load than 120 ohms. Well at least on this side of the pond.