8ohms into 4ohms??

[Sleeping Martyr]

I know its supposed to be bad but I jammed last night and someone had switched the cable from my head to my cab so my head was running 8ohms into 4ohms in the cabinet . . . . and it sounded amazing!!!! (I didn't relaize what happened till after the jam) so how bad IS it to run a setup like that?? It sounded really really good but I don't wanna blow anything up or anything

 

[STRATDELUXER97]

Re: 8ohms into 4ohms??

I know its supposed to be bad but I jammed last night and someone had switched the cable from my head to my cab so my head was running 8ohms into 4ohms in the cabinet . . . . and it sounded amazing!!!! (I didn't relaize what happened till after the jam) so how bad IS it to run a setup like that?? It sounded really really good but I don't wanna blow anything up or anything

It's not that it's bad but you get a mismatch when you don't match the impedences between your head and cab...You just never want your amp to see less than it's lowest ohm setting...If the head's lowest setting is 4 ohms,just don't allow the head to see anything below that...If the cab is 8 ohms and your amp can go down to 4,you're ok....:13:

Bottom line....You're always best to match the impedences for the head and cab whenever possible!

 

[LJ King]

Re: 8ohms into 4ohms??

Twin Reverbs have a fixed output impedance of 4 ohms. The internal speaker load is 4 ohms. Plug in a dual showman cab at 4 ohms as an extension speaker and the total speaker impedance becomes 2 ohms.

Never bothered Ted Nugent.

There are some amps botique types with an impedance selector switch labeled as a tone switch without impedance markings.

 

[WhoFan]

Re: 8ohms into 4ohms??

Twin Reverbs have a fixed output impedance of 4 ohms. The internal speaker load is 4 ohms. Plug in a dual showman cab at 4 ohms as an extension speaker and the total speaker impedance becomes 2 ohms.

Never bothered Ted Nugent.

There are some amps botique types with an impedance selector switch labeled as a tone switch without impedance markings.

I imagine there would have to be some sort of special designed Transformer for such a Tone Switch

 

[Baltar]

Re: 8ohms into 4ohms??

the reason why it sounded awesome may be, that your load mismacht
is causing a bad efficiency. you're more or less running the half power
of the amp. another way of a power soak, but i wouldn't do it to my amps.
a lot of people say it doesn't matter. but well - i care about it. .. and am afraid
to kill my amps.

 

[STRATDELUXER97]

Re: 8ohms into 4ohms??

Twin Reverbs have a fixed output impedance of 4 ohms. The internal speaker load is 4 ohms. Plug in a dual showman cab at 4 ohms as an extension speaker and the total speaker impedance becomes 2 ohms.

Never bothered Ted Nugent.

There are some amps botique types with an impedance selector switch labeled as a tone switch without impedance markings.

Ted probably could afford to replace transformers and speakers..

If the transformer is a good one this is do-able....Wouldn't recommend it with a stock OT in something like a BF Pro Reverb amp though....The Bassmans and Super Reverbs had transformers rated down to 2 ohms however..

 

[jeremy]

Re: 8ohms into 4ohms??

many good transformers can handle a one step mismatch, so 8 ohms to 4 ohms or 16 ohms to 8 ohms. you have to be careful going too low, 0 ohms is a short and really bad for tube amps. going too close forces the amp to work outside its comfortable parameters and can kill the tranny at the worst and run very hot shortening the life of tubes and/or other componants at best.

transformers sound best using all the winds, so a marshall 16/8/4 ohm tranny will sound best at 16 ohms.

 

[LJ King]

Re: 8ohms into 4ohms??

transformers sound best using all the winds, so a marshall 16/8/4 ohm tranny will sound best at 16 ohms.

That is a myth. Only a personal opinion from a "published tech" who will be more than willing to sell you the speakers you will more than likely need to accomplish it.

 

[STRATDELUXER97]

Re: 8ohms into 4ohms??

That is a myth. Only a personal opinion from a "published tech" who will be more than willing to sell you the speakers you will more than likely need to accomplish it.

Hmm....Possibly an anti Weber fan? :laugh2:

Anyway....Please backup your above statement regarding the 4/8/16 ohm myth for us..:13:

 

[LJ King]

Re: 8ohms into 4ohms??

Hmm....Possibly an anti Weber fan? :laugh2:

Anyway....Please backup your above statement regarding the 4/8/16 ohm myth for us..:13:

First of all, you should know there is no way to prove a negative.

Second, the vast majority of people do not critically distinguish between opinion from a popular person and fact.

Third, I also sell speakers and could probably sell a lot more if I supported this hype.

Fourth, Tone is a matter of personal preference. There is no electronic formula that gives tone as a result of combining various parameters.

Fifth, transformers have no way of knowing if a tap or the full winding is being used.

Sixth, if this were true, why do amp makers even bother with impedance taps and don't you think they would be the first to have realized it?

If you are really concerned and if I were you, I would ask the originator of this myth for his proof. Be specific and ask for the electronic formula that proves it. You won't get any.

Now I will refer you back to my second point.

 

[kmcguitars]

Re: 8ohms into 4ohms??

That is a myth. Only a personal opinion from a "published tech" who will be more than willing to sell you the speakers you will more than likely need to accomplish it.

IDUNNO. I recall Jeff Seal mentioning that he runs his 2203 on 16 ohms so all the winding are being used. Jeff is a highly qualified amp Tech/Guru with no monetary agenda to make a statement as such. Even if it is just his personal opinion? I'm sure it's based in some facts/knowledge.

 

[LJ King]

Re: 8ohms into 4ohms??

IDUNNO. I recall Jeff Seal mentioning that he runs his 2203 on 16 ohms so all the winding are being used. Jeff is a highly qualified amp Tech/Guru with no monetary agenda to make a statement as such. Even if it is just his personal opinion? I'm sure it's based in some facts/knowledge.

Thanks for posting!!

You know what a switch is... right? You know how it works - when it is closed it completes a circuit and current flows. When it is open, the circuit is incomplete and no current flows. The fact that current flow requires a complete circuit is fundamental in electronics.

So, If I am using the 8 ohm tap out of a maximum of a 16 ohm capability, what amount of current is flowing in that unused section between the 8 ohm and 16 ohm tap? Correct answer - none, because there is not a complete circuit to anywhere. This raises the question... aw, I'll let you figure out the question.

But let's assume the premise is valid - that I will get maximum tone out of my amp (however you would describe what that maximum tone would be) if I use all of the windings on the secondary side of the output transformer.

Now let's assume I am building an amp to get that maximum tone and that I will use the full secondary winding of the output transformer - since we have already agreed that premise is valid.

What impedance of secondary winding should I use?

This is a serious question. In my persuit of the maximum tone, what should be the value of the secondary winding impedance? Should I use 4... or 8... or 16 ohms? How about 32... or 1024 ohms? Maybe it should be 12 ohms???

Or should it magically not matter since no matter what value I wind the secondary to, I will be using the full winding?

Do you see the problem? You either have to discount one of the most fundamental and basic laws of electronics, or believe in some magical notion that the transformer somehow knows and/or somehow performs differently simply based on some length of unused wire on the secondary side and the impedance on that secondary side is somehow in and of itself not an issue (otherwise you could give me a maximum tone impedance for that secondary side).

I don't know if Jeff gets great tone or not. But if he does, this form of magic is not the reason.

 

[STRATDELUXER97]

Re: 8ohms into 4ohms??

First of all, you should know there is no way to prove a negative.

Second, the vast majority of people do not critically distinguish between opinion from a popular person and fact.

Third, I also sell speakers and could probably sell a lot more if I supported this hype.

Fourth, Tone is a matter of personal preference. There is no electronic formula that gives tone as a result of combining various parameters.

Fifth, transformers have no way of knowing if a tap or the full winding is being used.

Sixth, if this were true, why do amp makers even bother with impedance taps and don't you think they would be the first to have realized it?

If you are really concerned and if I were you, I would ask the originator of this myth for his proof. Be specific and ask for the electronic formula that proves it. You won't get any.

Now I will refer you back to my second point.

While I find your post very informative :Throw some smiley faces at us to show us you aren't all strickly serious and defensive business....:laugh2:

I'll send the back and forths to my friend Trace at Voodoo Amps and see what his opinions are on the subject...:beerchug:

 

[Sleeping Martyr]

Re: 8ohms into 4ohms??

so bottom line is?? 8 inot 4 is okay, bad or is it totally debateable?? My amp has an 8 ohm output and two 4 ohm outputs and the transformer is not the stock Mesa transformer, it had to be replaced a couple years ago and now I run it with a fan on it, would this make it more acceptable??

 

[STRATDELUXER97]

Re: 8ohms into 4ohms??

so bottom line is?? 8 inot 4 is okay, bad or is it totally debateable?? My amp has an 8 ohm output and two 4 ohm outputs and the transformer is not the stock Mesa transformer, it had to be replaced a couple years ago and now I run it with a fan on it, would this make it more acceptable??

Just match your impedences correctly and rock out! :6:

 

[LJ King]

Re: 8ohms into 4ohms??

so bottom line is?? 8 inot 4 is okay, bad or is it totally debateable?? My amp has an 8 ohm output and two 4 ohm outputs and the transformer is not the stock Mesa transformer, it had to be replaced a couple years ago and now I run it with a fan on it, would this make it more acceptable??

8 into 4 is ok, but it is best practice to match impedances. Mismatching can result in loss of power, loss of bandwidth, or both.

Are you saying that your output transformer is getting hot enough to need a fan? That would be unsual as under normal operation the output transformer stays relatively cool. Nothing like the power transformer which can get really hot.

Of course it could be picking up heat from the output tubes or maybe the way the enclosure is designed there is just not enough airflow.

 

[Sleeping Martyr]

Re: 8ohms into 4ohms??

Its the problem with the way Mesa .50 calibers are built, the transformers are RIGHT squeezed together, which causes the power transformer to heat up the output transformer