# Does Ohm load affect sound quality?



## vwjmkv (Apr 23, 2011)

I know that the lower the ohm load the more can be fed to a sub from an amp, but in my case (JL Slash 500/1v2) it gives out 500W regardless of ohm from 4 down to 1.5. 

I am curious if i should get a good 4ohm sub or should i even care about Ohms since my amp gives the same power regardless of Ohms...


just realized how many times i used the word "Ohm" 

Thanks for the help, 

CC


----------



## The A Train (Jun 26, 2007)

I believe you answered your own question


----------



## vwjmkv (Apr 23, 2011)

The A Train said:


> I believe you answered your own question


i believe i asked my own question... lol


----------



## studsicle (May 14, 2011)

I believed he's saying you're inexperienced enough to not be able to tell a difference. I wouldn't be offended by it, I would imagine it would be difficult for anyone to really tell a difference, experienced or otherwise.


----------



## MarkZ (Dec 5, 2005)

Sometimes there's a slight rise in harmonic distortion with decreased impedance, although sometimes it's hard to be able to distinguish between it being due to more power or being due to the lower impedance.

Sometimes, especially in class D or in amps with narrow output zobel filters (probably not terribly common in car audio?), using impedances much higher than the amp was designed for can have an impact on frequency response.

Short answer to your question -- impedance generally doesn't affect sound quality directly. There are two key words in that sentence: 

1) "generally" (to cover my ass in cases where amp designs are odd  )

2) "directly", which means that impedance can impact POWER OUTPUT which can affect performance in the obvious ways.


----------



## ChrisB (Jul 3, 2008)

There are some old school amplifier nut huggers that will say that every halving of impedance increases distortion and decreases damping factor thereby impacting sound quality. Unfortunately, I live in that place called the real world and know full well that most individuals can't hear distortion on subwoofers until they hit double digits. Next, the damping factor spec as it relates to car audio is nothing but a marketing number designed to sell more amplifiers, that's it. Furthermore, you are installing this in a hostile environment, of which you have little to no control over, and will generally have 70 to 100 decibels of extraneous engine/exhaust/road/tire/other vehicles/insert anything else here noise at speed.

Disclaimer: if you are one who sits in your driveway listening to music for hours on end or call yourself an audiophile, disregard what I just wrote and go on believing the marketing BS you were fed. What I wrote only applies to people who actually listen to music while driving their automobile in real world conditions.


----------



## The A Train (Jun 26, 2007)

Think of the RIPS as a buffer. Its purpose is to deliver the same power across a wide range of impedences and input voltages. So in short, any subwoofer with impedences between 1.5 and 4 ohms, will recieve the same power.


----------



## ChrisB (Jul 3, 2008)

The A Train said:


> Think of the RIPS as a buffer. Its purpose is to deliver the same power across a wide range of impedences and input voltages. So in short, any subwoofer with impedences between 1.5 and 4 ohms, will recieve the same power.


Also, any differences in sound quality will be negligible, at best. Then again, the OP could be one of those audiophile guys who hears grass growing and screaming when it is cut.

As for efficiency on the Slash series, isn't it bad to very bad?:laugh: I know that it wasn't designed to be efficient and heck, I even owned one at once up on a time myself. I noticed no significant differences in SQ on my 13w6v2 when comparing the 500/1 to these amplifiers that I ran on the same sub in the same car:
Clarion DPX1851
Crossfire BMF1000d
JL Audio HD900/5 (sub channel)
Linear Power 5002 @ 8 ohms
Lunar L2125 (bridged)
Orion HCCA 225 g5 (bridged)
Rockford Fosgate 25 to life Power 1000 (sub channel)
Rockford Fosgate power 1000BD
Soundstream Reference 700s (bridged)
Stetsom V 1K5 H 1 Ohm

With the exception of the Linear Power 5002, all of the other amplifiers were run at 2 ohms.


----------



## Swanson's Performance (Mar 27, 2011)

So amplifiers are somehow magically different from every other device we've designed and built in the transistor age? Running it harder and harder until it is near thermal meltdown doesn't change the sound at all, huh? So those changes in resistance as temperature goes up don't skew the signal going through the transistor? Wow. I guess all those electronics theories and testing sessions on lab days all had rigged oscilloscopes and a bad batch of indvidual components, right? MMkay.

While I will give you that frequencies below 80Hz might be harder to detect distortion in to the ear in general, unless you are filtering out a large portion of the signal with seatbacks and other portions of the vehicle, I'd guarantee if you were sitting with your ear in front of the sub and played at the same dB (say 85dB so that you don't need earplugs to satisfy OSHA requirements) that there would be a definite difference in audio quality when playing musical tones between 20-100Hz (as opposed to sine waves, pink noise, etc). The only way at all I see any way of your sound remaining the same is if the amp was actively cooled to the point that there was no measurable rise in the temperature of the transistors. Even then since the magnitude of current was so much higher at 1 ohm vs. 8 ohms, you'd still be altering the signal amplification. Amplifiers aren't surgical instruments that are capable of perfectly delivering an exact output.

Maybe it's not your amp that matters... maybe the box is altering the sound enough that the amplifier doesn't make a difference?? Port noise, box resonance, cabin resonance, etc etc etc could be introducing enough extraneous noise in your car that it would mask the distortion. And just how does efficiency play in to relating to the SQ factor at all?


Plus, if all of those amps were run at 2 ohm loads except for 1 single amplifier, how is that a valid comparison to anything? Maybe if you had run all the amps at 2 ohms and 8 ohms you might have some valid comparisons.


----------



## ChrisB (Jul 3, 2008)

Bottom line... I've run amplifiers from 1 ohm all the way up to 8 ohms in the car. When it comes to subwoofers, the combination of the subwoofer, enclosure, and proper design for the environment is MORE important than one's choice in amplifier or impedance load, assuming they have an amplifier DESIGNED to run at the impedance that they are running it at. Note I use DESIGNED versus STABLE, because that is a HUGE difference. Usually, those DESIGNED for 1 ohm operation will cost a lot more than those that are just advertised as 1 ohm stable.

Regardless, the 1 ohm argument is moot anyhow because a 1.5 ohm DCR load is closer to 2 ohms nominal. IIRC, I tried my 500/1 at 1 ohm (.75 DCR) and RIPS wouldn't even allow it to power up.


----------



## Hanatsu (Nov 9, 2010)

ChrisB said:


> Bottom line... I've run amplifiers from 1 ohm all the way up to 8 ohms in the car. When it comes to subwoofers, the combination of the subwoofer, enclosure, and proper design for the environment is MORE important than one's choice in amplifier or impedance load, assuming they have an amplifier DESIGNED to run at the impedance that they are running it at


Agree. If I don't require the power I rather go for higher impedance than lower. My Dayton RS180 runs fine at 8ohm, amp should give around 40-45W at 8ohm nom load. Amp runs cooler and you save current load from the electrical system. My DLS Iridium12s are DVC subs, 2ohm or 8ohm depending on connection. Amps have no trouble running them in series, I reach desired output anyway and my amps probably live for a few years longer


----------



## vwjmkv (Apr 23, 2011)

Hanatsu said:


> Agree. If I don't require the power I rather go for higher impedance than lower. My Dayton RS180 runs fine at 8ohm, amp should give around 40-45W at 8ohm nom load. Amp runs cooler and you save current load from the electrical system. My DLS Iridium12s are DVC subs, 2ohm or 8ohm depending on connection. Amps have no trouble running them in series, I reach desired output anyway and my amps probably live for a few years longer


i think this is the answer i was looking for. perhaps not so much as SQ or "better sound" [whatever that means] but i think i will run a 4Ohm sub to not stress the Amp. 

i coworker of mine recently fried his amp, the dumbs read the manual, the manual said amp not stable at 1Ohm and the dumbass ran 2 subs at a 1 Ohm load... "bye bye" he said to his brand new amp, the day after he bought it. 

CC


----------



## vwjmkv (Apr 23, 2011)

ChrisB said:


> Then again, the OP could be one of those audiophile guys who hears grass growing and screaming when it is cut.


:laugh::laugh::laugh::laugh::laugh::laugh: i am NOT "one of those guys" i like good sound but i can't hear the grass cry when its cut... 

CC


----------



## MarkZ (Dec 5, 2005)

Swanson's Performance said:


> So amplifiers are somehow magically different from every other device we've designed and built in the transistor age? Running it harder and harder until it is near thermal meltdown doesn't change the sound at all, huh? So those changes in resistance as temperature goes up don't skew the signal going through the transistor?


Now you're getting it! 



> Wow. I guess all those electronics theories and testing sessions on lab days all had rigged oscilloscopes and a bad batch of indvidual components, right? MMkay.


Which theories are you referring to?

Amplifiers are designed to be incredibly robust to variations in temperature and impedance. The way they do this is by employing global negative feedback. We're not talking about using a single emitter follower and calling it an "amplifier". Amplifier circuits are far more complex than this, and they're designed to reduce the effect of component variance with temperature, with drift, and with tolerance. Global negative feedback serves as a correction measure which tailors the input to account for distortion at the output.

This is also why the tolerance of the components you use is pretty much unimportant to the operation of the amplifier (with very few exceptions... primarily, the feedback resistors, the LPF that governs the freq dependence of the feedback, the bias circuit, and the output zobel -- which, IME, most car amps lack).

So, although you're correct that component values can vary considerably with temperature -- especially bipolar betas, it turns out that beta values don't actually matter in the design! If you don't believe me, I'll provide some examples.


----------



## MarkZ (Dec 5, 2005)

vwjmkv said:


> i think this is the answer i was looking for. perhaps not so much as SQ or "better sound" [whatever that means] but i think i will run a 4Ohm sub to not stress the Amp.


Amps are not human beings.  They don't get "stressed". They don't "work hard". They're designed to amplify, and a byproduct of that is that they generate heat. As long as you're operating _within the design range of the amp_, you should be fine. Really, the designers are usually pretty good at their jobs, and more often than not, the marketing departments don't claim that their amplifiers can do something they can't really do (class action law suits and all... ). If a manufacturer says that an amp is 1 ohm stable, I tend to believe them. Of course, "1 ohm stable" may not mean 1 ohm stable mounted under a carpet on a 110deg day and blaring music with the gain turned up to the point where you're overdriving the amp by 50% or more, but if you're doing that you have other problems. 

Anyway, it's perfectly reasonable to want to generate less heat to avoid thermal failure. I get that. But keep in mind that you can always choose to run an amp at 1 ohm and generate the same amount of heat as at 4 ohms simply by turning the gain down! If the amp is delivering 100w into a speaker at 1 ohm, it's dissipating (roughly) the same amount of heat as when it's delivering 100w into a speaker at 4 ohms. And the speaker is playing just as loudly under both conditions. This is _especially_ true for class D, G, and H amps, btw, which show much less variation in efficiency as a function of output voltage.

But best of all, in the 1 ohm configuration above, you're less prone to clipping. This is a pretty significant benefit, IMO.


----------



## vwjmkv (Apr 23, 2011)

MarkZ said:


> Amps are not human beings.  They don't get "stressed". They don't "work hard".


I am not trying to anthropomorphize amplifiers. just trying to geive better descriptions and shorten my post. I find it more efficient to say i dont want to stress the amp, rather than i dont want that amp to overheat. i believe we all know amps are not humans. we all just try to be efficient when describing our opinions.

Thank you for your input though. I think i will go with a 4Ohm load on the amp. 

CC


----------



## Swanson's Performance (Mar 27, 2011)

MarkZ said:


> Amps are not human beings.  They don't get "stressed". They don't "work hard". They're designed to amplify, and a byproduct of that is that they generate heat. As long as you're operating _within the design range of the amp_, you should be fine.


LOL... Mark, I have read some really solid things you've said on here, but this really has me laughing. Amps don't get "stressed"? Amps don't "work hard"? Heh. So exactly how do people get many amps to destroy themselves, or blow fuses, or so many other things that release the magic white smoke when they take a 4-ohm sub, and wire it to a 4-ohm amp? Or whatever the design range is. Of course the amp gets "stressed", and "works hard", otherwise it would never get hot to the touch, or go into thermal protection, etc. This is also why amplified signal distortion goes up exponentially after a certain amount of power is produced by an amplifier. Efficiency and the "design power" play more into not generating heat than an amplifier not working hard. It's simple physics that if you take an amp rated at 400W continuous and run it for say 24 hours at 400W, it will experience more "stress" than an amp of the same quality but designed for say 2000W continuous. Meaning, take two Mosconis and compare them, not a 400W Flea Market and a 2000W Tru Technology amp. 

As great as negative feedback loops are, they are not flawless, and they have many implementations which do not all work the same, or work without altering the amplified signal in some way that is not true to the original signal. By your own admission, the feedback loop is required because the amplifier is *not* as perfect as you initially imply and say that 100W is 100W is 100W. It would be really awesome if that were the case, but then of course we'd all have 1000W amps with .000001% distortion at maximum continuous rated power, would only draw 79 amps at full power, and would cost about $99 at every TDH store around the world. If all amps did was amplify and not alter the signal, then why are there $69 500W amps and $3,000 500W amps? A nicer user's manual?


----------



## MarkZ (Dec 5, 2005)

I know what you meant. But I think you're anthropomophizing them unknowingly. There's nothing really to be gained by running them cooler than cool. It's not like a mechanical device that might show greater torsional strain the harder you work it. They'll amplify the signal the same way when they're "working hard" or not. They don't start to sputter and cough at high output levels.

You're certainly free to run your amp at 4 ohms, but I hope it's not due to the idea that it will sound better. Most of the time, it will actually sound worse at higher impedances because you clip more readily at the same output (although this, as you know, is not the case for the JL amps).


----------



## MarkZ (Dec 5, 2005)

Swanson's Performance said:


> LOL... Mark, I have read some really solid things you've said on here, but this really has me laughing. Amps don't get "stressed"? Amps don't "work hard"? Heh. So exactly how do people get many amps to destroy themselves, or blow fuses, or so many other things that release the magic white smoke when they take a 4-ohm sub, and wire it to a 4-ohm amp?


They blow amps by not operating the amp within its design limits. I admit that it's easier to do running low impedance loads. But that's not the fault of the load, it's the fault of the user being unable to adjust his gain correctly and/or choosing an amp that's too small for his intended goals.



> Or whatever the design range is. Of course the amp gets "stressed", and "works hard", otherwise it would never get hot to the touch, or go into thermal protection, etc. This is also why amplified signal distortion goes up exponentially after a certain amount of power is produced by an amplifier.


Ha, no. It goes up exponentially in the graphs you've seen because it starts clipping. 



> Efficiency and the "design power" play more into not generating heat than an amplifier not working hard. It's simple physics that if you take an amp rated at 400W continuous and run it for say 24 hours at 400W, it will experience more "stress" than an amp of the same quality but designed for say 2000W continuous. Meaning, take two Mosconis and compare them, not a 400W Flea Market and a 2000W Tru Technology amp.


 Please define "stress" before you start trying to invoke physical laws. Are you talking about failure, or are you talking about operation? Failure rates tend to rise exponentially once you begin to approach the transistors' SOA curve, below which there's a very small difference. In terms of operation, I believe I covered that by explaining why beta variation doesn't matter pretty much anywhere (I'll admit it starts to matter in the bias tracking circuit, but that's only because 99% of car manufacturers don't do it correctly).



> As great as negative feedback loops are, they are not flawless, and they have many implementations which do not all work the same, or work without altering the amplified signal in some way that is not true to the original signal. By your own admission, the feedback loop is required because the amplifier is *not* as perfect as you initially imply


This makes absolutely no sense. You can't take part of an amplifier out and still call it the same amplifier! That would be like taking the transmission out of your car and saying "this car isn't a very good car, the transmission is just covering up its inability to go down the street by itself." Negative feedback is universally considered a good design strategy (except by readers of Stereophile, who don't understand what feedback actually does...).

Staying on topic though, you haven't explained how the NFB circuit in your amplifier fails to do the things I mentioned. Are you disputing that it makes beta variations irrelevant?


----------



## vwjmkv (Apr 23, 2011)

MarkZ said:


> I know what you meant. But I think you're anthropomophizing them unknowingly. There's nothing really to be gained by running them cooler than cool. It's not like a mechanical device that might show greater torsional strain the harder you work it. They'll amplify the signal the same way when they're "working hard" or not. They don't start to sputter and cough at high output levels.
> 
> You're certainly free to run your amp at 4 ohms, but I hope it's not due to the idea that it will sound better. Most of the time, it will actually sound worse at higher impedances because you clip more readily at the same output (although this, as you know, is not the case for the JL amps).


LMAO - my poor amp is going to cough and sputter OH NO! Me thinks that youre thinking of emotional stress. and we all know our amps wont start coughing/sputtering. I think ill be safe with the 4 Ohms. the sub will be 400W RMS and the JL amp is 500W RMS im pretty sure ill be safe.

Thank you for your input

CC


----------



## ChrisB (Jul 3, 2008)

MarkZ said:


> (except by readers of Stereophile, who don't understand what feedback actually does...).


I already dismissed Swanson as a reader of Stereophile just based on the comments he's made in this thread. Are we not talking about audio in a car which is the absolute worst environment for the reproduction of said audio?

Anyhow... Congrats Swanson, you remind me of yet another audiophile kool-aid drinker. Bravo, I applaud you!


----------



## Swanson's Performance (Mar 27, 2011)

OK, I'll bite. How are you claiming that beta variations (correction factor for people who might not give a crap on how an amp works, just how it sounds) do not matter when they are directly responsible for how the NFB works? I'll admit, it's been a long time since I've bothered to think about this part of amplification, but I'm always up for some good-humored discussions to stimulate the grey matter


----------



## ChrisB (Jul 3, 2008)

vwjmkv said:


> LMAO - my poor amp is going to cough and sputter OH NO! Me thinks that youre thinking of emotional stress. and we all know our amps wont start coughing/sputtering. I think ill be safe with the 4 Ohms. the sub will be 400W RMS and the JL amp is 500W RMS im pretty sure ill be safe.
> 
> Thank you for your input
> 
> CC


Slave master vwjmkv, please don't work your amp too hard for it may die an untimely death due to being forced to reproduce those test tones masquerading as music.:laugh:

Now crack that whip!


----------



## Swanson's Performance (Mar 27, 2011)

vwjmkv said:


> LMAO - my poor amp is going to cough and sputter OH NO!


Better give it some Robitussin! See Chris Rock for usage details....

http://www.youtube.com/watch?v=YsY2-yi5W74


----------



## rc10mike (Mar 27, 2008)

I have an experience I feel I need to throw out there. 

I was running a PPI amp to my subs (two RF Punch HX2s) in a sealed box. They were getting about 800w from the PPI and it sounded good. But I wanted a 5ch all-in-one solution so I went with a RF Power 1000. Its rated at 1000w @ 1 ohm. 

So I wired everything up to 1 ohm. I figured it was going to sound the same, after all the only thing I changed was the amp. Holy sh!t I was wrong, the subs sounded like crap. I couldnt put my finger on it, but it sounded nothing like the PPI. 

So I tried rewiring the subs to 4 ohm. Granted its not ideal sending only 250w to a pair of 500w subs, I just wanted to see what would happen.

I was extremely surprised to hear that the subs "life" had been brought back so to speak, it sounded much like the old PPI, granted I couldnt listen to them very loud since it would clip so easily. 

The difference was HUGE for me in that case, and if I still had the amp, I would invite anyone to come hear the difference.


----------



## vwjmkv (Apr 23, 2011)

Swanson's Performance said:


> Better give it some Robitussin! See Chris Rock for usage details....
> 
> Chris Rock - Robitussin - YouTube


Ill have to rub some Mo Tussin on my amp...

CC


----------



## ChrisB (Jul 3, 2008)

rc10mike said:


> I have an experience I feel I need to throw out there.
> 
> I was running a PPI amp to my subs (two RF Punch HX2s) in a sealed box. They were getting about 800w from the PPI and it sounded good. But I wanted a 5ch all-in-one solution so I went with a RF Power 1000. Its rated at 1000w @ 1 ohm.
> 
> ...


I had quite the opposite experience with another amplifier... I owned a Crossfire BMF1000d that I ran at 8 ohms and it heated up faster than it did when run at 1 ohm and sounded like crap at 8 ohms. In the amplifier's defense, it wasn't rated at 8 ohms, but it was an interesting revelation to say the least. It kind of went against the theory of higher impedance loads sounding better. 

I discussed the results of that experiment with an amplifier designer that I am friends with, and unfortunately his explanation went above my head. Had something to do with VI limiting and lower impedance loads versus higher loads and some other circuitry lingo that went over my head. I'm a CPA, not an electrical engineer.:laugh:


----------



## rc10mike (Mar 27, 2008)

ChrisB said:


> I had quite the opposite experience with another amplifier... I owned a Crossfire BMF1000d that I ran at 8 ohms and it heated up faster than it did when run at 1 ohm and sounded like crap at 8 ohms. In the amplifier's defense, it wasn't rated at 8 ohms, but it was an interesting revelation to say the least. It kind of went against the theory of higher impedance loads sounding better.
> 
> I discussed the results of that experiment with an amplifier designer that I am friends with, and unfortunately his explanation went above my head. Had something to do with VI limiting and lower impedance loads versus higher loads and some other circuitry lingo that went over my head. I'm a CPA, not an electrical engineer.:laugh:


Probably something to do with the high voltage needed to drive high impedances.


----------



## ChrisB (Jul 3, 2008)

rc10mike said:


> Probably something to do with the high voltage needed to drive high impedances.


In layman's terms, he did say that some of those class d amplifiers were designed to be loaded down, and not loading them down caused the problems I encountered.... like oscillation and heat.

Again, I could be screwing that up because 1. I was drunk when it was explained to me and 2. the only thing I have in common with an engineer is that I took college level physics and calculus courses.


----------



## MarkZ (Dec 5, 2005)

Swanson's Performance said:


> OK, I'll bite. How are you claiming that beta variations (correction factor for people who might not give a crap on how an amp works, just how it sounds) do not matter when they are directly responsible for how the NFB works? I'll admit, it's been a long time since I've bothered to think about this part of amplification, but I'm always up for some good-humored discussions to stimulate the grey matter


First of all, yes you're right, for others reading this... beta is the property of a bipolar transistor that governs how much it "amplifies" current. If you have a beta of 100, then when you put in 1mA you get out 100mA. Beta is known to change pretty strongly based on temperature. 

Of course, transistors aren't actually USED in this way ("in" and "out" aren't really part of the transistor nomenclature  ). Transistors are usually part of a circuit... sometimes the circuit is designed to make use of beta, sometimes it's designed to make the beta value meaningless (within a particular range). An example of a circuit where beta doesn't matter would be a current mirror.

Ok, on to your post...

NFB doesn't rely on beta either! NFB is usually implemented in the input stage differential amplifier, where the input signal is compared to the output signal. Since the output depends on this difference, that's where the term "feedback" comes in to describe the strategy. The weighting of the feedback relies primarily on a voltage divider at the input of the differential amp, and on a capacitor somewhere which governs how feedback deals with high frequencies (you usually roll off high frequency feedback for the sake of stability). The only beta in the feedback circuit is the beta of the differential amplifier, but that too only affects weighting.

Again, the only beta values that make any difference on the output of the amplifier come from the bias. If your bias changes with temperature, then you get crossover distortion or gm-doubling distortion. A properly designed bias tracking circuit is used to keep your bias constant despite temperature fluctuations. I won't speak to how well they do this in car audio amps -- it's possible that some designers do better than others -- but if they're not doing it right, then that means that there's a single "optimum" temperature which is going to depend on a hell of a lot more than impedance!

But the point is that temperature has only minimal effects on the output of an amplifier... not because components don't change with temperature (they do!), but because the circuit is designed specifically to account for all that.

Edit: And as I mentioned earlier, you don't necessarily have to run your amp at higher power levels just because it's wired down to 1 ohm! If you run it at the same power output as in the 4 ohm case, then the temperature is going to be (roughly) the same in both cases. This means that _impedance _isn't the culprit here, the gain knob is. Impedance is not going to have an impact on a class B amp, except where damping factor is concerned, and that's only because damping factor is defined by it.  [And no, damping factors are waaaay too high in class B amps to be of any concern in this thread..]


----------



## MarkZ (Dec 5, 2005)

ChrisB said:


> In layman's terms, he did say that some of those class d amplifiers were designed to be loaded down, and not loading them down caused the problems I encountered.... like oscillation and heat.


Yes, an engineer from a popular (well, not popular in this forum...  ) manufacturer told me something similar re: their class D amps. They're designed to run at 1 ohm. He said using higher impedances was a no-no because it changed the effective filter parameters at the output. The output of a class D amp is basically a passive crossover, so it's no surprise that changing the load impedance affects this.

Like I said earlier, I think the best bet is to use the amp as the designers intended it to be used. Or mod it to do what you want, like I did to my a/d/s/.


----------



## ChrisB (Jul 3, 2008)

MarkZ said:


> Like I said earlier, I think the best bet is to use the amp as the designers intended it to be used. Or mod it to do what you want, like I did to my a/d/s/.


No more modding for me... The last time I rewound a transformer, upped capacitance, and changed out emitter resistor values, it worked fine. 

Until the fire.


----------



## BuickGN (May 29, 2009)

Back when I had my 12W6 infinite baffle, I tried it at 2ohm and at 8ohm and at first I thought it was my imagination but it played the upper frequencies (90hz) much easier at 2ohm. I got a friend to swap it between 2 and 8ohms a few times while I listened not knowing which configuration it was in and I got it right every time. Not sure if it can affect inductance or not but the subs definitely sounded better at 2ohm in the upper sub bass frequencies. So I would have to say yes, the ohm load can affect SQ. Maybe I need to run a little experiment with my IB15s and HD900/5 and see if I can reproduce it or if it was limited to that sub and amp combo.


----------



## MarkZ (Dec 5, 2005)

BuickGN, if it was a narrow bandwidth class D amp, this could be consistent with the idea that the load impedance affects the usable freq range of the amp (the output filter class D issue described earlier).

But to do that experiment correctly, you MUST hold power constant in the comparison. If you drop the impedance of the load, it's going to be louder at the same gain setting (those JL amps being the exception...).


----------



## BuickGN (May 29, 2009)

MarkZ said:


> BuickGN, if it was a narrow bandwidth class D amp, this could be consistent with the idea that the load impedance affects the usable freq range of the amp (the output filter class D issue described earlier).
> 
> But to do that experiment correctly, you MUST hold power constant in the comparison. If you drop the impedance of the load, it's going to be louder at the same gain setting (those JL amps being the exception...).


It was an old class D infinity that was not capable of going past 300hz so yes, it probably fits your description. Oh well, I thought I was on to something, thanks.


----------



## cvjoint (Mar 10, 2006)

What about amplifier headroom? Let's abstract a second from continuous power ratings. Is the JL going to have the same headroom for instantaneous short duration demands regardless of the imp load? I'm not quite sure how to account for headroom in amplifiers. 

Do you match CEA ratings to IEC or AES ratings is the bigger question.


----------



## nubz69 (Aug 27, 2005)

It can make a difference but it is small. I have noticed the difference between wiring a sub in 2 ohm or 8 ohm. Usually the 8 ohm will sound a bit better/tighter. Might be magic, might be damping factor.


----------



## kyheng (Jan 31, 2007)

Well, there's alot of factors on running at 1ohm load or 8ohm load. 
Amp's gain, damping factor(not that important BTW), power supply, amp's design..... All comes into play. 
If your power supply are not enough to produce big power, wire the sub at 1ohm may result to poor SQ, wire the sub at 8ohm may help abit.... Again, there's no right or wrong on this...


----------



## Hanatsu (Nov 9, 2010)

If you have set gains correctly the amps should not clip. If you get enough output at higher nominal impedance I don't see the reason why that isn't a good thing. Then there's this little issue. See that spec the manufactures present, you never gain exactly twice the power as you go down in impedance. Example: Amp X [email protected] - [email protected] - [email protected], if the amp was perfect it should have looked like this 100w-->200w-->400w. But if you go down in impedance load you will not lose more than half and as some thread here have stated, some 8ohm speakers have higher sensitivity than the 4ohm version, you'll have the same SPL at given load anyway.

Get a big amp and load it less. I almost certainly believe that will sound better than a small amp louded high. Unless you building a SPL system there cannot be a reasonable point why running speakers at 1ohm for example. Need higher output, buy a bigger amp. I have never run an amp below 2 ohm in my builds, haven't found the need for it

My opinion, that's all


----------



## rc10mike (Mar 27, 2008)

I would like to know what Mark has to say about my RF Power 1000 experience...


----------



## MarkZ (Dec 5, 2005)

Hanatsu said:


> If you have set gains correctly the amps should not clip. If you get enough output at higher nominal impedance I don't see the reason why that isn't a good thing. Then there's this little issue. See that spec the manufactures present, you never gain exactly twice the power as you go down in impedance. Example: Amp X [email protected] - [email protected] - [email protected], if the amp was perfect it should have looked like this 100w-->200w-->400w.


You're right that you're not doubling power when comparing 4 and 2 ohm (or quadrupling power when you compare 4 and 1 ohm, etc). But you're still increasing power quite substantially. On the flip side, there's absolutely no benefit sound-wise to running higher impedances.



> But if you go down in impedance load you will not lose more than half and as some thread here have stated, some 8ohm speakers have higher sensitivity than the 4ohm version, you'll have the same SPL at given load anyway.


This is usually not true. I know there's a thread dedicated to the idea that higher impedances yield higher sensitivity, but most speakers don't actually exhibit this property. For example, the Dayton RS180-4 actually has higher sensitivity at 1w/m than the 8 ohm version.



> Get a big amp and load it less. I almost certainly believe that will sound better than a small amp louded high.


But you haven't explained why you believe this. :/


----------



## MarkZ (Dec 5, 2005)

rc10mike said:


> I would like to know what Mark has to say about my RF Power 1000 experience...


How did you adjust the gains when you rewired it to 4 ohms?


----------



## rc10mike (Mar 27, 2008)

MarkZ said:


> How did you adjust the gains when you rewired it to 4 ohms?


I don't remember but I did have the remote gain knob on the dash. The thing is though, I could hear the difference at low volume. 
Edit: the remote knob overrides the amp gain.
Sent from my DROID RAZR using Tapatalk


----------



## MarkZ (Dec 5, 2005)

rc10mike said:


> I don't remember but I did have the remote gain knob on the dash. The thing is though, I could hear the difference at low volume.


Yeah, but the point is that if you didn't match the gains to the rest of the system in exactly the same way then it's difficult to make the comparison.


----------



## rc10mike (Mar 27, 2008)

MarkZ said:


> Yeah, but the point is that if you didn't match the gains to the rest of the system in exactly the same way then it's difficult to make the comparison.


Even is the difference was easily heard at all levels? 

Sent from my DROID RAZR using Tapatalk


----------



## MarkZ (Dec 5, 2005)

rc10mike said:


> Even is the difference was easily heard at all levels?


It's not about the absolute gain. It's about the relative gain between it and the rest of your audio. It's well documented that how a sub sounds is highly dependent on what the rest of the audio system is doing relative to it -- e.g. "boomy", "lacking impact", etc.


----------

