# Some Things that I Run Into on a daily Basis



## 22689 (Mar 25, 2009)

1. People contact me saying they want a subwoofer - and it has to be dual 2 Ohm because they HEARD that would be louder. So I ask what amp they are using and they tell me they don't have one yet. 

a 1 ohm sub is not louder than a 2 ohm sub or even a 4 ohm sub etc...

if I have a 2Ohm stable and 2 ohm load from a sub, then it will run louder than a 4ohm load sub on the exact same amp. But that does not make that sub less loud. The Subs Ohm Load Makes the AMP push 1/2 The watts that the 2Ohm load sub made it push. 

4 ohm stable amp with the same watt output as the above mentioned 2Ohm stable amp - Pushing the 4 ohm load sub - side by side would be exactly the same output. 

If You run that 2Ohm sub on the 4Ohm stable amp it will attempt to push twice the power it was intended to push and it will FRY the amp - possibly Damage the sub. protection circuitry in the amp will kick in for awhile and then one day it will just give up trying to warn you by shutting off and cooling down and it will just start smoking and burn up. 

I have explained this to so many people it is incredible, most do not get it still. Some have gone so far as to call me names and post horrible things (In My eyes anyway ) 
Some continue to blindly install with no idea what and Ohm even is. 

Then they blame the product for the failure. OR WORSE!!! ME!!! lol. 

once you learn the basics down pat in your head for the loads for multiple speaker installs and basic amp operations - it sticks in your head like riding a bike, just do it and get it down - buy a digital ohm load meter and never look back. Your days of not ruining the coolest stuff on earth will begin. :O) 
Even the Pros use the Manuals, it's not a sign of weakness to look at a manual. For real. I won't even do an install without checking and rechecking everything several times before power. 

GL. I know this post will seem silly to some of you. but like I was saying, I get it all the time so apparently it's not said enough.


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## Z80_Man (Apr 22, 2010)

A single dual 2 ohms coils subwoofer may still be a very wise choice, provided you have a mono amp able to drive a 1 ohm load, so you'll be able to use its full power.

Another good trick is to try to use bridged amps when it's possible, as they generally have a better damping factor when bridged.

As most of them are limitated to driving 4 ohms loads in this mode, then you can use your dual coil subwoofer with the coils wired in serial - OK, I know it's stupid because you just had to buy a single 4 ohms coil instead, but I just wanted to illustrate the fact that it's usable with a lot of amps setups. 

You could also think about bi-amping... Most, if not all amplifiers will drive 2 ohms loads, and some can even do that when bridged, so you would be able to use their full available power AND maximize damping.

What would you want better ? :laugh:

If you intend to use more than one subwoofer, they it's even better, as you'll be able to combine serial and parallel setups to fit any amplifier.

So don't just throw away the idea : better think about what you exactly intend to do with them instead, before buying, of course.


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## chad (Jun 30, 2005)

Z80_Man said:


> Another good trick is to try to use bridged amps when it's possible, as they generally have a better damping factor when bridged.


Better as in half of?

Do the math, the output channels of a bridged amp are in series to double the output voltage, thus doubling the output impedance of the amplifier. 

When you put resistors in series their resistance sums.

To calculate damping factor you divide the load impedance by the output impedance of the source. 

So if you are driving a 4 ohm sub with a single channel with an output impedance of .01 Ohm you would have a damping factor of 400

Put those channels in series to gain voltage you now have an output impedance of .02 ohms thus a damping factor of 200

Not Bettar, but far from noticeable in terms of damping factor.. considering tube amps have an ideal damping factor of... ONE.... and people really dig those. (You need to match impedance in tube amps between output transformer and speaker, so 4/4 is?... ONE)


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## ChrisB (Jul 3, 2008)

I want someone to explain how they HEAR damping factor!


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## ptwat (Oct 13, 2010)

What is not being considered here is the acoustic efficiency of the speakers. A horn loaded speaker is has much more acoustic efficiency that a cone speaker. Properly driven 4 ohm speaker can sound as loud (acoustic power) as a properly driven 2 ohm speaker with the same input power depending on the acoustic efficiency of the speakers. Power transfer also depends on frequency. A 2 ohm speaker is not 2 ohms at all frequencies even in the usable acoustic range.
Another aspect is that a doubling of power (acoustic or electrical) only results in a 3 dB change is loudness. 3dB is at or near the limit of noticeable change of loudness for most people.
My point is that some people get hung up on a particular aspect of a sound system and it may not make a lot of difference compared to the system as a whole.


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## chad (Jun 30, 2005)

ptwat said:


> What is not being considered here is the acoustic efficiency of the speakers. A horn loaded speaker is has much more acoustic efficiency that a cone speaker. Properly driven 4 ohm speaker can sound as loud (acoustic power) as a properly driven 2 ohm speaker with the same input power depending on the acoustic efficiency of the speakers. Power transfer also depends on frequency. A 2 ohm speaker is not 2 ohms at all frequencies even in the usable acoustic range.
> Another aspect is that a doubling of power (acoustic or electrical) only results in a 3 dB change is loudness. 3dB is at or near the limit of noticeable change of loudness for most people.
> My point is that some people get hung up on a particular aspect of a sound system and it may not make a lot of difference compared to the system as a whole.













Damn straight.


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## Frasier (Jul 16, 2010)

ptwat said:


> 3dB is at or near the limit of noticeable change of loudness for most people.


Actually that's 1dB you're thinking of, with some able to hear 0.5dB or less. Still, 3dB is nowhere near the huge difference most people would expect to hear from doubling the system power.


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## Sarthos (Oct 29, 2010)

I thought that running a sub into series made it a little bit louder per watt of output. Or is that just because the output resistance on the amp becomes a bit smaller compared to the load resistance of the sub?

But running an amp at 4 ohms instead of 1 ohm does generally help with cooling since you output higher voltage and lower amperage right?


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## ptwat (Oct 13, 2010)

Frasier said:


> Actually that's 1dB you're thinking of, with some able to hear 0.5dB or less. Still, 3dB is nowhere near the huge difference most people would expect to hear from doubling the system power.


Actually 1dB is not what I was thinking of but let's not split hairs.


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## chad (Jun 30, 2005)

3dB is NEAR the limit.


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## Frasier (Jul 16, 2010)

ptwat said:


> Actually 1dB is not what I was thinking of but let's not split hairs.


By "what you're thinking of" I meant the number that's normally quoted for what you were talking about--Obviously I'm not psychic.



chad said:


> 3dB is NEAR the limit.


NEAR is a very relative term. A 10dB increase means about DOUBLE the perceived loudness. Have you ever used a gain control with dB increments? 3dB is not a subtle change, and I personally would not refer to it as near the limit.

Regardless, I never meant to pull the thread off topic or start an argument. Let's just agree that 3dB is not a big change in the context of this thread.


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## chad (Jun 30, 2005)

Frasier said:


> Have you ever used a gain control with dB increments?


All day, every day (except most Sundays.) It's noticeable, but not "holy **** noticeable."


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## GRIFTER9931 (Aug 30, 2009)

ChrisB said:


> I want someone to explain how they HEAR damping factor!


Hop on over to head-fi.org and some of those genius's will relate you a tale of being able to hear warmth and damping and many other interesting audio terms.


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## chad (Jun 30, 2005)

This section brings out teh humors. Love it!

I can only handle so much head-fi. one of my grad student tech was a fan of that place, built this MONSTER headphone amp out of op-amps, a ****load of them. That thing had some balls. It hung with my D75, yes, I use the speaker outs of a Crown D75 as a headphone amp.


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## Frasier (Jul 16, 2010)

chad said:


> It's noticeable, but not "holy **** noticeable."


Which is what we've all been saying this whole time. As ptwat said, let's not split hairs.


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## chad (Jun 30, 2005)

Frasier said:


> As ptwat said, let's not split hairs.


something about p*twat* and splitting hairs had me rolling there.

But if you came to me and said, you should rip your install apart, and install twice as much amplifier to gain 3dB.. I would kindly decline. Not worth it. It's not gonna bring the Rawk.


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## mikey7182 (Jan 16, 2008)

chad said:


> Damn straight.


"In case any of these little bastards get outta line, I get to take them down... ain't that right motherFUCKA!?" When he pulls on those reins of that miniature horse, I ****ing lose it EVERY time.


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## Z80_Man (Apr 22, 2010)

ChrisB said:


> I want someone to explain how they HEAR damping factor!


Yes, it's basically the ability to control the membrane excursion so it won't shag with unwanted harmonics.

A higher damping factor amp will keep the speaker just moving as it should instead of running loose ! :laugh: Or at least, it will try.


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## mikey7182 (Jan 16, 2008)

Z80_Man said:


> Yes, it's basically the ability to control the membrane excursion so it won't shag with unwanted harmonics.
> 
> A higher damping factor amp will keep the speaker just moving as it should instead of running loose ! :laugh: Or at least, it will try.


I think he understands what damping factor is... what we're curious about is what the end user will hear between an amp with a higher damping factor and one with a lower damping factor. What does it SOUND like? What perceivable differences are there?


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## Z80_Man (Apr 22, 2010)

mikey7182 said:


> I think he understands what damping factor is... what we're curious about is what the end user will hear between an amp with a higher damping factor and one with a lower damping factor. What does it SOUND like? What perceivable differences are there?


Flabby sound when the amp is unable to control the membrane movements... 

There's another topic about that, BTW.


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## chad (Jun 30, 2005)

Z80_Man said:


> There's another topic about that, BTW.


Absolutely, start it, I'm in. Have both points of view, but it's pretty black and white.

My view can easily be searched by searching Whipsnades, or UD, Or useless drivel.


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## DaveRulz (Jun 22, 2006)

imeverlast said:


> Some continue to blindly install with no idea what and Ohm even is.


coming from a person who uses the term "ohm load" vs impedance....


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## Sarthos (Oct 29, 2010)

Subs get louder running at lower impedances because of the higher wattage (if your amp is stable to run the lower impedance). Otherwise, the lower impedance doesn't make the sub louder on its own.
But aren't there lots of other advantages to running the high impedances? 
I mean, you want to have as LOW of a damping factor as possible, because all that a high damping factor does is heats up your amp.
And also, doesn't running the subs into low resistances result in the voice coil inductance being greater compared to the sub's resistance, putting your current further out of phase with the voltage and making the speaker *less* efficient?


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## normalicy (Jun 30, 2009)

The main reason anyone ever got into low impedances in the first place is because of competition & the power classes. People could get into the 50w class by using an amp rated at 2x25w & run the thing down to 1/2 an ohm to get the most out of it.

These days it's not so much an issue with the higher power classes. Not to mention, 99% of people don't actually compete anyhow. The best suggestion as has been mentioned is just to plain run the amp to it's lowest rated stable impedance to get the most for your money. Not to say that it'll hurt anything to play it safe & use one at a higher impedance. Just get a more powerful amp or a fancy-smancy one that has load detection. Thus, I agree with the author that the impedance of the sub is not the defining factor on how loud it gets.


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## 22689 (Mar 25, 2009)

DaveRulz said:


> coming from a person who uses the term "ohm load" vs impedance....


 Impedance is not something that someone who I would be addressing with this thread would understand. Seems a lot of people that didn't even need any info in here are in here adding info. 

It's Nice that you commented on such an important thing however, I am sure it will truly help someone out. 

Impede load : I am Pretty sure there is a joke in here somewhere and you would be the incredible butt of it. I just don't want to waste anymore time on this. LOL Insert Joke here __________________________________________________________________________________________________________________________________________________________. 

Thanks. Extra points for including Mom and/or Dad.


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## ghostmechanic (Mar 2, 2009)

normalicy said:


> The best suggestion as has been mentioned is just to plain run the amp to it's lowest rated stable impedance to get the most for your money.


That's easily bad advice. I'm speaking as someone that has repaired a butt load of amps. Just because the amp is theoretically "stable" or even a higher current model able to double wattage every time you drop the speaker impedance in half, doesn't mean the amp is completely safe. I've seen a bunch of amplifiers (some brands it's more common) that the power supply is destroyed from voltage sagging. When you drop the impedance like that, you also need to make sure you have enough of an electrical system to support it. Some amps will double the power but become grossly less efficient & start consuming a bunch of current. Then there are also many amps out there that may be "stable" down to "x ohms" but still don't put out much more power because of how stiffly regulated their power supply is.


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## 22689 (Mar 25, 2009)

ghostmechanic said:


> That's easily bad advice. I'm speaking as someone that has repaired a butt load of amps. Just because the amp is theoretically "stable" or even a higher current model able to double wattage every time you drop the speaker impedance in half, doesn't mean the amp is completely safe. I've seen a bunch of amplifiers (some brands it's more common) that the power supply is destroyed from voltage sagging. When you drop the impedance like that, you also need to make sure you have enough of an electrical system to support it. Some amps will double the power but become grossly less efficient & start consuming a bunch of current. Then there are also many amps out there that may be "stable" down to "x ohms" but still don't put out much more power because of how stiffly regulated their power supply is.


AWESOME POINT - works in reverse as well. 

run a 2 ohm stable amp at 4 ohm - Higher quality signal - less drain - amp will run all day without getting over heated - Amp lasts longer because its not working is ass off. You might even get away with running a cheap ass wal mart battery. 

Consider running your brand new Ferrari at full throttle pulling a boat through town stopping at all the lights and then Jamming on the gas. seems a little stupid eh? It will last way longer if you read the instructions and understand them. LOL 

The Power and wiring is something that people mess up on all the time, they don't consider the fact that the amp draw is killing it ans a lot of people don't even see that the correct wire and power source can bring their amp to it's full capabilities. I have seen a system that ran every day for years and was just unreal. 17Volts continuous to each amp ( 4 X KX1200.1 - .5Ohm) These amps "On Paper" should have overheated and burnt to a crisp after their protection circuitry finally gave out - but since they had the power they craved they didn't even shut off. 

Not to get off subject: Battery Caps are responsible for SO MANY failures it's insane!

P.S I love My HC2400's LOL


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## Oh.humes (Dec 22, 2010)

The best suggestion as has been mentioned is just to plain run the amp to it's lowest rated stable impedance to get the most for your money.


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## kvndoom (Nov 13, 2009)

The *best *suggestion is to charge 1 dollar for each new forum registration so the ****ing spam bots can disappear forever.


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## ghostmechanic (Mar 2, 2009)

kvndoom said:


> The *best *suggestion is to charge 1 dollar for each new forum registration so the ****ing spam bots can disappear forever.


:laugh:


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## illcrx (Nov 11, 2010)

1. The main problem that I see with the original question here is the lack of knowledge of the general public. If someone comes up talking about the sound of ohms then they obviously are ignorant on the subject and need some education. 

2. I didnt see a 2?


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## HondAudio (Oct 19, 2006)

illcrx said:


> 1. The main problem that I see with the original question here is the lack of knowledge of the general public. If someone comes up talking about the sound of ohms then they obviously are ignorant on the subject and need some education.
> 
> 2. I didnt see a 2?


The "sound of ohms"? Units of electrical resistance don't make noise


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## sqshoestring (Jun 19, 2007)

That depends on how fast your sub is and how many electrons are left in your wire. LOLs  Amps sure do get less efficient at lower loads, that is power consumed per watt output. If you wanted efficient you would run a typical 4/2 ohm capable class D sub amp at 4 ohms, buy a larger or two amps for more power if you need to. I don't think they get that much more efficient at 8 ohms but not much info to find on that.


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