Speakers, Amps & Ohms... Help
Road Captain
Joined: Feb 2007
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RE: Speakers, Amps & Ohms... Help
ORIGINAL: tlb
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
If you want to, for some reason, consider how loud you can get a speaker to go with an amp of a certain power, recognize that power depends on the impedance of the speakers, so an amp rated for 100 watts at 8ohms is probably about 175 watts at 4 ohms (not quite double). Same vice versa. Take the speaker efficiency, apply it to watts of your amp into the impedance load, and you'll determine potential volume.
Here's reality: If you want max volume and high quality sound, you need an amp. If you're just replacing speakers for sound quality at reasonably loud listening levels, replace them with speakers with nominal impedance of anything greater than half the ohm rating of your factory radio amplifier and don't sweat it. You're only at risk of hurting your amp if you know you're pushing the limits of your amplifier, and its a toss-up whether you'd blow your amp or speakers first in that situation anyway.
Road Captain
Joined: Feb 2007
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RE: Speakers, Amps & Ohms... Help
ORIGINAL: RonH
OK everyone, get out your audio books and turn to chapter 3, today we'll be studying "The Inverse Square Law"......
: )
OK everyone, get out your audio books and turn to chapter 3, today we'll be studying "The Inverse Square Law"......
: )
Here's the skinny: Don't worry about ohms so much. Just go listen to some speakers, pick ones that sound good to you, try to match ohms the best you can, and don't push the limits of your radio's amplifier or speakers regarding volume. If you want more volume or better sound quality at high volume, add an amplifier.
Elite HDF Member
Joined: Apr 2007
Posts: 4,984
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RE: Speakers, Amps & Ohms... Help
OK gunner, so you corrected the way I used the word volume, I attempted to give him a basic answer and a brief explanation at the same time. Now if you wish we can actually do the math along with it now, I am capable of it. I am also capable of calculating the amount of kinetic energytransferred when the amp becomes junk and he has to toss it. I can also discuss what exactly happens when you turn up the gain on an amp. Which by the way not a good way of solving an ohm issue. It's all good, glad you got to flex a bit even if it is not rocket science and you are not giving good advice, ohms are important.ride safe
ORIGINAL: grinner
Not really. You'll have half the POWER. Not half the volume. It takes twice the POWER to create only a 3db gain in volume, not a 10db gain in volume (10db gain is twice the volume, 3db gain is "noticeable"). Speaker efficiency is how volume / watt is measured. Some speakers are more efficient than others, and a small increase / decrease in efficiency has a large effect on max volume.
If you want to, for some reason, consider how loud you can get a speaker to go with an amp of a certain power, recognize that power depends on the impedance of the speakers, so an amp rated for 100 watts at 8ohms is probably about 175 watts at 4 ohms (not quite double). Same vice versa. Take the speaker efficiency, apply it to watts of your amp into the impedance load, and you'll determine potential volume.
Here's reality: If you want max volume and high quality sound, you need an amp. If you're just replacing speakers for sound quality at reasonably loud listening levels, replace them with speakers with nominal impedance of anything greater than half the ohm rating of your factory radio amplifier and don't sweat it. You're only at risk of hurting your amp if you know you're pushing the limits of your amplifier, and its a toss-up whether you'd blow your amp or speakers first in that situation anyway.
ORIGINAL: tlb
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
If you want to, for some reason, consider how loud you can get a speaker to go with an amp of a certain power, recognize that power depends on the impedance of the speakers, so an amp rated for 100 watts at 8ohms is probably about 175 watts at 4 ohms (not quite double). Same vice versa. Take the speaker efficiency, apply it to watts of your amp into the impedance load, and you'll determine potential volume.
Here's reality: If you want max volume and high quality sound, you need an amp. If you're just replacing speakers for sound quality at reasonably loud listening levels, replace them with speakers with nominal impedance of anything greater than half the ohm rating of your factory radio amplifier and don't sweat it. You're only at risk of hurting your amp if you know you're pushing the limits of your amplifier, and its a toss-up whether you'd blow your amp or speakers first in that situation anyway.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
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From: Naples FL / Pine TWP PA
RE: Speakers, Amps & Ohms... Help
Wow - A ton of partially correct information and partially wrong information. In simple terms an amplifier is designed to push a certain load a at a rated power output and distortion figure. It may or may not be capable of pushing a lower impedance speaker. You need to check with the amplifier manufacturer to verify any given amplifier's capabilities. The THD (total harmonic distortion) may be horrible into a 2 ohm load and perfectly acceptable into a 4 ohm load. Know what I mean? You are almost always safe going to a higher impedance speaker at the cost of (power) volume.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
RE: Speakers, Amps & Ohms... Help
ORIGINAL: tlb
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
RE: Speakers, Amps & Ohms... Help
ORIGINAL: tlb
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
The output of an amplifier is not DC linear. Some amplifiers will almost behave the way you described above and others will not. Keep in mind there are three basic classes of amplifier: A, B, C. Each has its advantages. Most modern stereo amplifiers are class B, class A-B, or rarely class A. The problem with your power output assumptions is that you have a pure class A amplifier capable of very low impedance loads. This is highly unlikely in a automotive application because of the power consumption requirements. So in all likelihood an amplifier designed for a 4 ohm load is going to sound like crap into a 2 ohm load because it is most likely a high quality class B amplifier.
Amplifier classes:
A - High fidelity high power consumption
B - Trade off between Class A and Class C
C - low fidelity with good power efficiency
Elite HDF Member
Joined: Apr 2007
Posts: 4,984
Likes: 8
RE: Speakers, Amps & Ohms... Help
I would agree, however, he said his current setup has 2ohm speakers which would lead to he has a 2 ohm amp, I dont know this just assumption based on the information provided, he asked can I put 4 ohm speakers on a 2 ohm amp? I said in along version yes just at half the volume, I know not really half but a simple answer. He also said he gets distortion, I tried to tell him he will still get the distortion even if he changes the ohm rating on the speakers. I agree if he is using a 4 ohm amp on a 2 ohm speaker it maybe why he is getting distortion I had not thought of this fact, very good point.
Would it be safe to say:
1.He wants to temporarily put in new 4 ohm speakers is fine but he may lose volume.
2. look at his amp see if it is 4 ohm it may solve his distortion problem by changing the speakers to match the amp.
3. Assume if he is attempting to hear his music at 70mph he needs it turned up. Therefore, matching the ohm rating on the amp to the speakers is important.
4.If he is going to use it around town at 25mph then using his amp at mid-range the ohm rating is less important.
5. Next time someone asks a simple question, more than likely will not want an in-depth answer or even really understand it just adding to confusion, short 2-3 word answers are better.
Would it be safe to say:
1.He wants to temporarily put in new 4 ohm speakers is fine but he may lose volume.
2. look at his amp see if it is 4 ohm it may solve his distortion problem by changing the speakers to match the amp.
3. Assume if he is attempting to hear his music at 70mph he needs it turned up. Therefore, matching the ohm rating on the amp to the speakers is important.
4.If he is going to use it around town at 25mph then using his amp at mid-range the ohm rating is less important.
5. Next time someone asks a simple question, more than likely will not want an in-depth answer or even really understand it just adding to confusion, short 2-3 word answers are better.
ORIGINAL: FX4
Additionally,
The output of an amplifier is not DC linear. Some amplifiers will almost behave the way you described above and others will not. Keep in mind there are three basic classes of amplifier: A, B, C. Each has its advantages. Most modern stereo amplifiers are class B, class A-B, or rarely class A. The problem with your power output assumptions is that you have a pure class A amplifier capable of very low impedance loads. This is highly unlikely in a automotive application because of the power consumption requirements. So in all likelihood an amplifier designed for a 4 ohm load is going to sound like crap into a 2 ohm load because it is most likely a high quality class B amplifier.
ORIGINAL: tlb
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
Yes you can put 4 ohm speakers on a 2 ohm amp but, you will have half the volume
I will explain this a couple of different ways.
first way:
ohms are resistance, amps are rated for X watts @ X ohms
therefore, double the speaker ohms half the wattage of the amp rating.
half the ohm speaker rating double the amp out wattage but produces a lot of heat in the amp.
second way:
An amplifier designed to put out 100 watts into4 ohms will put out 200 watts into2 ohms.(high heat)
An amplifier designed to put out 100 watts into2 ohms will put out50 watts into4 ohms.(low heat) half the volume, same distortion
Two4 ohms speakers wired in parallel (2 ohms total) would cause the amplifer to produce 200 watts.(high heat)
Two8 ohms speakers wired inseries (4 ohms total) would cause the amplifer to produce50 watts.(low heat but still heat)
High heat will kill and amp.
The output of an amplifier is not DC linear. Some amplifiers will almost behave the way you described above and others will not. Keep in mind there are three basic classes of amplifier: A, B, C. Each has its advantages. Most modern stereo amplifiers are class B, class A-B, or rarely class A. The problem with your power output assumptions is that you have a pure class A amplifier capable of very low impedance loads. This is highly unlikely in a automotive application because of the power consumption requirements. So in all likelihood an amplifier designed for a 4 ohm load is going to sound like crap into a 2 ohm load because it is most likely a high quality class B amplifier.
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Road Captain
Joined: Feb 2007
Posts: 513
Likes: 74
From:
RE: Speakers, Amps & Ohms... Help
Tlb - I agree with you. Good advice. But cut power in half, volume goes down 3db. That's barely noticeable. Not half. Otherwise, combine your response and my skinny one, and I think we've got it solved.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
RE: Speakers, Amps & Ohms... Help
ORIGINAL: grinner
Tlb - I agree with you. Good advice. But cut power in half, volume goes down 3db. That's barely noticeable. Not half. Otherwise, combine your response and my skinny one, and I think we've got it solved.
Tlb - I agree with you. Good advice. But cut power in half, volume goes down 3db. That's barely noticeable. Not half. Otherwise, combine your response and my skinny one, and I think we've got it solved.