Presenting an amp with the right impedance if you don't have the right speakers...
- Thread starter Pierre
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marvar
New member
Re: Presenting an amp with the right impedance if you don't have the right speakers..
Although it would get you in the ballpark- you probably won't like the sound of it- a resistor sucks alot of tone and volume.
Plus- remember that a speaker is actually a variable resistor, it doesn't hold a constant value,but is rated at a nominal impedence, the impedence of a speaker changes as you play louder and softer.
Although it would get you in the ballpark- you probably won't like the sound of it- a resistor sucks alot of tone and volume.
Plus- remember that a speaker is actually a variable resistor, it doesn't hold a constant value,but is rated at a nominal impedence, the impedence of a speaker changes as you play louder and softer.
Artie
Peaveyologist
Re: Presenting an amp with the right impedance if you don't have the right speakers..
I don't think you'll really have a problem. (True amp techs, correct me if wrong.) A speaker changes imedance with frequency, not power. An 8 ohm resistor will simply drop your speaker volume by 3 db, or half power. You'll be doing the same thing as a power attenuator, but in a slightly different way.
Your biggest problem will be that you'll need an 8 ohm resistor of fairly high wattage. (Not easy to find.) Lets say you have 30 watt amp. At a bare minimum, you'ld need a 15 watt resistor. But thats not even good because you don't want that resistor to run at full power. Probably not even half. Which means, realistically, you'ld probably want a 50 - 100 watt resistor. Not cheap, and not easy to find. An 8 ohm, 100 watt resistor will be about the size of a toilet-paper roll. (Got one in front of me.)
I don't think you'll really have a problem. (True amp techs, correct me if wrong.) A speaker changes imedance with frequency, not power. An 8 ohm resistor will simply drop your speaker volume by 3 db, or half power. You'll be doing the same thing as a power attenuator, but in a slightly different way.
Your biggest problem will be that you'll need an 8 ohm resistor of fairly high wattage. (Not easy to find.) Lets say you have 30 watt amp. At a bare minimum, you'ld need a 15 watt resistor. But thats not even good because you don't want that resistor to run at full power. Probably not even half. Which means, realistically, you'ld probably want a 50 - 100 watt resistor. Not cheap, and not easy to find. An 8 ohm, 100 watt resistor will be about the size of a toilet-paper roll. (Got one in front of me.)
Re: Presenting an amp with the right impedance if you don't have the right speakers..
Dang you Artie - you know I can't resist a challenge like that!! :rocket:
By acknowledging that a speaker changes impedance with frequency how could you possibly conclude that including an 8 ohm resistor will drop the speaker volume by 3db? What resistor do you know of that also changes it's resistance value with frequency? :bigok:
Even RadioShack has a 20 watt 8 ohm resistor - assuming you really wanted to place a resistor in series with an 8 ohm speaker. Why would it take a 50-100 watt resistor to dissapate 15 watts?
Run a resistor at full power? A resistor doesn't have power. It dissapates it.
Ok - enough fun.
The question is: is it safe to connect an 8 ohm speaker to an amp with a 16 ohm output.
The simple answer is yes. You will lose either bandwidth, power or both - but it will not be harmful to the amp or speaker.
Tube amps are not as fragile as most of the internet will have you believe.
I assume you are talking a tube amp... as a solid state amp requiring 16 ohms of speaker load doesn't make much sense.
And an amp can't TAKE - but it can PROVIDE. Not the same thing at all.
Dang you Artie - you know I can't resist a challenge like that!! :rocket:
By acknowledging that a speaker changes impedance with frequency how could you possibly conclude that including an 8 ohm resistor will drop the speaker volume by 3db? What resistor do you know of that also changes it's resistance value with frequency? :bigok:
Even RadioShack has a 20 watt 8 ohm resistor - assuming you really wanted to place a resistor in series with an 8 ohm speaker. Why would it take a 50-100 watt resistor to dissapate 15 watts?
Run a resistor at full power? A resistor doesn't have power. It dissapates it.
Ok - enough fun.
The question is: is it safe to connect an 8 ohm speaker to an amp with a 16 ohm output.
The simple answer is yes. You will lose either bandwidth, power or both - but it will not be harmful to the amp or speaker.
Tube amps are not as fragile as most of the internet will have you believe.
I assume you are talking a tube amp... as a solid state amp requiring 16 ohms of speaker load doesn't make much sense.
And an amp can't TAKE - but it can PROVIDE. Not the same thing at all.
Artie
Peaveyologist
Re: Presenting an amp with the right impedance if you don't have the right speakers..
(Pulls soldering iron from holster.)
Granted, the 3db figure is approximate, but the change in impedance is already accounted for in the design of the amp. Adding a resistor won't hurt anything.
A 15-watt resistor run at 15 watts is going to get very hot. I like a little breathing room.
On the rest . . . we agree.
(Pulls soldering iron from holster.)
LJ King said:
Granted, the 3db figure is approximate, but the change in impedance is already accounted for in the design of the amp. Adding a resistor won't hurt anything.
LJ King said:
A 15-watt resistor run at 15 watts is going to get very hot. I like a little breathing room.
On the rest . . . we agree.
Pierre
Stratologist
Re: Presenting an amp with the right impedance if you don't have the right speakers..
Ahhh you got what I mean about the provide/Take thing
. I basically didn't want to damage speaker nor Output transformer. I know it's not really dangerous but I'd rather get it all right. Good point about the resistor, I didn't realize high wattage ones were that hard to find.
On another hand I'm glad my reasoning was...er... almost correct
Ahhh you got what I mean about the provide/Take thing
. I basically didn't want to damage speaker nor Output transformer. I know it's not really dangerous but I'd rather get it all right. Good point about the resistor, I didn't realize high wattage ones were that hard to find.On another hand I'm glad my reasoning was...er... almost correct
Re: Presenting an amp with the right impedance if you don't have the right speakers..
Hold it!! Let me get mine tinned first!!
Keep in mind I do not recommend putting in a resistor to meet some "impedance" number as it isn't necessary.
But if you did, the 15 watt resistor isn't even going to get slightly warm.
I think your assumption is that the 30 watt amp will deliver 15 watts continuous to the resistor, and that is simply not true.
And that reason is why Fender has been able to put two 12" speakers into it's 100 watt twin reverbs that are only rated to handle 40 watts RMS total for both speakers.
The Oxford 12T6-10.
(Pulls soldering iron from holster.)
Granted, the 3db figure is approximate, but the change in impedance is already accounted for in the design of the amp. Adding a resistor won't hurt anything.
A 15-watt resistor run at 15 watts is going to get very hot. I like a little breathing room.
On the rest . . . we agree.
Hold it!! Let me get mine tinned first!!
Keep in mind I do not recommend putting in a resistor to meet some "impedance" number as it isn't necessary.
But if you did, the 15 watt resistor isn't even going to get slightly warm.
I think your assumption is that the 30 watt amp will deliver 15 watts continuous to the resistor, and that is simply not true.
And that reason is why Fender has been able to put two 12" speakers into it's 100 watt twin reverbs that are only rated to handle 40 watts RMS total for both speakers.
The Oxford 12T6-10.
muttonchopsrule
New member
Re: Presenting an amp with the right impedance if you don't have the right speakers..
why not buy a new speaker with the correct impedence rating?
why not buy a new speaker with the correct impedence rating?
drpietrzak
New member
Re: Presenting an amp with the right impedance if you don't have the right speakers..
I plug each into my Weber z-matcher (assuming the watt rating is fine).
I plug each into my Weber z-matcher (assuming the watt rating is fine).
The Golden Boy
Fleecy Sweaterologist
Re: Presenting an amp with the right impedance if you don't have the right speakers..
Add another 8 ohm speaker in series?
Add another 8 ohm speaker in series?
