4 ohm speakers vs 8 ohm receiver --- Some questions!

[Soulstice]

Hey,

I've done a enough research to know that it should work fine, given my receivers power out-put and current characteristics.

I realize that driving 4 ohm speakers places more of a strain on my Yamaha, but I wanted bookshelf units for the rear and I found a pair of 160 W units for real cheap.


Anyway, I just want to know the following:

1. Is there an artificial method of adding an extra 4 ohms of impedence, say, for instance, by adding a resister or some sort to the speaker wire prior to entering the speaker inputs?

2. I've seen enough forum posts specific to people driving 4 ohm speakers with their 8 ohm receivers, and nobody seems to be reporting any issues (other than when attempting to output to the 4 ohm speakers at max volume levels). What have been your experiences doing this, and have you had any issues?


My setup is as follows:

Receiver: Yamaha HTR-6130
Front Speakers: KLA-9
Sub: Energy (too lazy to go grab the exact model number)
Rear speakers: Missil MA-302 (bookshelf units)

 

[obobski]

does the receiver have 4ohm numbers? if not, I wouldn't suggest it for long term/in general

furthemore, I would not suggest having mismatched loads on the amplifier (I honestly don't even like to do this on prograde QSC or Crown amplifiers, which are designed for that kind of abuse, simply because of the extra heat and so on, I prefer to have an additional amp if thats the case)

as far as if this should work (as in: obob is just turning a blind eye and giving you a generalistic answer), yeah, it'll probably go fine, the receiver will run hot, and the caps will die sooner than spec (meaning you might get 5-6 years out of the unit, as opposed to 10-20), just don't expect max volume (also, you'll probably have some efficiency mismatch issues between the front and rear speakers, should be fun to EQ (hopefully this unit has YPAO))

worst case scenario: it goes fine for a while, the thing overheats and hits clipping protection, shuts off, nothing should be damaged (but I wouldn't suggest you play it again if this happens)
absolute worst case: the magical smoke escapes from your yamaha (never heard of this on electrodynamic VCs though, ESLs and compression drivers sure)

 

[Soulstice]

What about adding a resister to up the impedence value to 8 ohms? Is this possible, and is it recommended?

 

[obobski]

What about adding a resister to up the impedence value to 8 ohms? Is this possible, and is it recommended?

you'd need many resistors, it would create a literal fuckton of heat, severely cramp your amplifier's performance, introduce a wonderful mess of circuitry which may, or may not (likely will), degrade audio performance (remember that heat? oh and the whole quality of components thing)

basically: of course you can wire random shit in between the speakers and amplifier, that doesn't mean you *should*

theres a reason spec sheets exist, they tell you whats compatable and what isn't

 

[Soulstice]

Okay... what about wiring two 4 ohm speakers in series? Wow... I wish I could remember my electrical courses from 10 years back in college. lol... I know how resistance works in a DC circuit, but I remember there was a specific method of adding impedence when working in AC... ...shit, I can't remember what was involved.... if it was as simple as adding a resister to the series, or something else? I guess I could break out my old text books... ...in fact, it probably will only take me a few minutes to look up.

 

[obobski]

Okay... what about wiring two 4 ohm speakers in series? Wow... I wish I could remember my electrical courses from 10 years back in college. lol... I know how resistance works in a DC circuit, but I remember there was a specific method of adding impedence when working in AC... ...shit, I can't remember what was involved.... if it was as simple as adding a resister to the series, or something else? I guess I could break out my old text books... ...in fact, it probably will only take me a few minutes to look up.

dude, just get speakers that are compatable, jeez

there are issues with series wiring, namely:

-it becomes a mono channel

- the amplifier isn't designed for that kind of load (oh did I mention where VCs dont conform to ANY rules, and do not have a uniform impedance across the freq range (and are not purely capacitive, resistive, etc (where this matters: say they hit 10ohms on the bottom end, now you're presenting 20 ohms to the amplifier, which it cannot handle either)), furthermore, the amplifier would have to be able to drive a good deal of power into this new "single channel" (oh did I mention your HTR won't hit rated WPC any day of the week, because the components aren't capable of it), so basically this series channel will demand more power than anything else on the amp (remember that heat?)

- sound quality degradation is likely to be horrific, as series wiring screws with available current/voltage swing

- the speakers aren't designed for it (yeah, they have some passive circuitry in there, it isn't designed to have another speaker "tied on")

seriously, accept that you made a booboo in buying 4 ohm speakers for an amp that isn't designed for it, return them, and buy something thats compatable, you might also buy something tonally balanced with your mains, so you don't have to spend a thousand hours in the EQ/calibration setup to make it sound right

as a postscript:
I know you won't listen, will come up with some new quip, and will continue wanting to argue this, because I doubt there is any teaching you here
so if you screw up, say hi to jesus for me, or at least take pictures of the fire

 

[Soulstice]

Dude, chill.

haha... I appreciate the advice, but I'm not spending anymore on speakers. If I shorten the life of my receiver from 15 years to 7 years, that's fine. I assume that, in 7 years, there's probably going to be features and functionality that I require and I'll have to upgrade anyway.


And, in terms of adding a speaker in series, it would be the exact same brand / model, so the impedence characteristics shouldn't be all over the place. I realize that different speakers rated at 4 ohms can have totally different characteristics, but the same brand / model should, theoretically, stay consistent. As for the draw on the amp, 8 ohms is better than 4, is it not?

But, no need to argue this, because I won't be purchasing another set to up the impedence level (even though the price is worth it).

I honestly thought that there would be a cheap conversion method... ...I've performed power conversions with everything from AC fans to UPS supplies equipped with the incorrect voltage settings, and I just thought that, having had to do it in other areas of IT, it wouldn't be a big deal for a basic home theatre system.

I guess I was wrong... lol

 

[Soulstice]

And, for the sake of not sounding like I'm a "know-it-all", or that I'm just hard-headed and don't listen to sound advice, I've done my due diligence: http://www.audioholics.com/educatio...hm-speakers-to-an-8-ohm-receiver-or-amplifier

 

[obobski]

Dude, chill.

haha... I appreciate the advice, but I'm not spending anymore on speakers. If I shorten the life of my receiver from 15 years to 7 years, that's fine. I assume that, in 7 years, there's probably going to be features and functionality that I require and I'll have to upgrade anyway.


And, in terms of adding a speaker in series, it would be the exact same brand / model, so the impedence characteristics shouldn't be all over the place. I realize that different speakers rated at 4 ohms can have totally different characteristics, but the same brand / model should, theoretically, stay consistent. As for the draw on the amp, 8 ohms is better than 4, is it not?

But, no need to argue this, because I won't be purchasing another set to up the impedence level (even though the price is worth it).

I honestly thought that there would be a cheap conversion method... ...I've performed power conversions with everything from AC fans to UPS supplies equipped with the incorrect voltage settings, and I just thought that, having had to do it in other areas of IT, it wouldn't be a big deal for a basic home theatre system.

I guess I was wrong... lol

my point is, return the speakers you have, and get a pair of speakers that are suited to this amplifier, instead of buying four speakers to do what two should do

as far as "8 ohms is better than 4", true, but you're also doubling the power requirements in that same jump, meaning what once took 20W, now takes 40W, if you did this on two channels, thats going to put your receiver into overload (because the thing isn't really designed to run all channels driven @ wpc spec)

honestly I don't like that audioholics link for a few reasons:
A) the aversion to the impedance switch, it does have a purpose, it drops the voltage output at the taps and keeps the amplifier from blowing itself apart, UL certification exists for a reason (seriously getting sick of internet audiophiles who believe ALL regulatory and engineering bodies are there just to "screw them out of sound quality")

B) the assumption that 4 ohm speakers ALWAYS overheat an amplifier, there are plenty of high end units which will drive 1 ohm or lower without flinching, and many quality receivers will drive 6 or 4 ohm speakers without much issue, yeah, you're gonna get heat with any amp, but seriously, it isn't always an overheat scenario

its basically trying to condense knowledge into a linear relationship (what the human mind likes dealing with), because it raises readership, which means more ad $$$ (oh yeah....), personally I'd rather just go with what the thing is spec'd for, because those #'s exist for a reason (NO, LIES, ITS JUST THERE TO SCREW YOU, US AUDIOPHILES KNOW BETTER, THATS WHY WE HAVE $500 USB CABLES AND $100,000 IEC CABLES! )

like I said in my first reply, yes, you can probably connect these to the surround outputs, and yes, it will run hotter than it would without them connected (it would do so even with 8ohm speakers, you're using more juice to drive more channels), the specs actually do show 6ohm and 4ohm numbers (Granted, they're scam numbers, but they still exist), which means the unit can likely handle itself reasonably well with these speakers (and I looked this up since you didn't answer my first question)

so it should do 5.1 or 4.1 (whatever you have speakers for, didn't see a center, but that doesn't mean you don't have one ), as long as you don't have a towel or something on top of it, and it can get air (this should be the case regardless of WHAT is plugged into it, it does have spec'd clearance #'s on all sides for a reason)

as far as high volume destroying it, it'd likely do so even with 8ohm speakers on every channel, the xformer and so on can't handle it (lets see, UL spec at 240W max power consumption, rated 500W+ output with ~50-60% efficient amplifier circuitry, yeah thats totally possible )

 

[Soulstice]

First of all, I want to thank you for all the advice / information.

In theory, you're absolutely right, and, as a network consultant, I generally give my customers / clients the exact same advice. I never build systems out of spec, and, when it comes to power, I've seen enough "dirty" AC in buildings resulting in damaged equipment to know how much of an important impact conditioning / UPS systems make.

However, I bought these speakers because I found a boxed set for $29 CD, at a place called XSCargo. Sometimes they get crazy shit, from other stores that have gone out of business, overstock at other outlets, etc, and you end up paying a fraction of what something normally costs. I was fully aware of the 4 ohms rating, but I thought... "shit, this beats spending $200 per speaker online or at local audio store... I'm sure there is a simple way to convert it...."

Obviously, as I began to research this, it turns out that, even by adding a resister, I can muck up sound quality, introduce additional heat (I already knew that.... that's what a resister does... acts as a load!), etc.



Anyway, you mentioned that you looked up my amp specs, and stated that it supports 4 ohms. I'm looking at the specs as well, and I did see that... ...but the wording is odd.

Maybe you can explain it to me.

First, it states that (for Canada / US models), Dynamic Power can support IHF, 8/6/4/2 ohms at 110/130/160/180 Ws... ...but, where it reads:

Max Power Per Channel (US / Canada models) it only mentions 8 ohms at 135 W/ch

And, as for RMS Output Power for front, center, and surround, it reads as 8 ohms ...... 100 W / ch.

So, WTF.... does my Yamaha support 4 ohm speakers or not? And if the Dynamic Power is the rating that matters, it also supports 2 ohm loads apparently?

Can you possible explain this to me?

Thanks again.

 

[keenan]

You're looking at these rating numbers the wrong way. They're not 'my amp can only be pushed this hard' numbers, they're 'going all out, this is how the amp performs' numbers. I have no idea what IHF is, but you can basically ignore the dynamic power and max power numbers, they're pretty meaningless. The RMS output is 100W @ 8R. Since your amp appears to be designed around an 8 ohm load and apparently doesn't have an impedance switch, asking it to drive a 4R load means that at its full output voltage you'll probably be asking it to push 200+W/ch when it can barely do 100W. Most receivers are built with enough protection circuitry that it will shut itself off long before this, but it's still not really a good idea to push it that hard.

It will work, but like obob I wouldn't really recommend it. If you like to listen loud, it will be easy to clip the amp and damage your speakers and possibly your receiver as well. You'll also likely have a bit of a hard time balancing the system.

 

[Soulstice]

You're looking at these rating numbers the wrong way. They're not 'my amp can only be pushed this hard' numbers, they're 'going all out, this is how the amp performs' numbers. I have no idea what IHF is, but you can basically ignore the dynamic power and max power numbers, they're pretty meaningless. The RMS output is 100W @ 8R

Fair enough, but that was the only place where I noticed the 4 ohms listed. obobski pointed out that my Yamaha HTR-6130 did mention support for 4 ohms in the previous post, and I just wanted to confirm. Since Dynamic Power was the only spec I noticed 4 ohms listed, I'm assuming that this is what he's referring to. 4 ohms was listed in two other sections, but it specifically stated that it only applied to European models, etc.

 

[obobski]

the yamaha does have an impedance switch, pp. 11-12 in manual

I'd suggest setting it for 6ohms, just to keep the voltage clamp on, it isn't "asking" for 200W in the first place, its simply going to get less voltage at the same output level, at the same current, assuming the amplifier can drive high current, which it doubtfully can, hence I wouldn't crank it (for the third time, haha)

like I said, it'll work, it'll just get warm, and it might die a few years sooner than expected, a better receiver would honestly be my suggestion if you're on an upgrade frenzy (for future reference, HTR is yamaha's crap CE line)

as far as getting speakers for $29:
yeah ignore me saying to replace them, I figured you got some $200 package and didn't wanna hastle with the return, namely out of pride or something, but yeah, $29, hell I i'd do it too, and if they blow, who cares

regarding IHF:
its marketing bullshit numbers, like I said, scam numbers

 

[keenan]

it isn't "asking" for 200W in the first place, its simply going to get less voltage at the same output level, at the same current, assuming the amplifier can drive high current, which it doubtfully can, hence I wouldn't crank it (for the third time, haha)

Well maybe the wording is loose, but speaker amps are voltage gain devices. Their design contract is to provide x dB of voltage gain, and they will try to satisfy that into any load, and with any input. If the amp fails to do that, it'll be due to protection circuitry or parasitic limitations (or outright component failure). I don't think it would 'simply get less voltage', the amp is going to try to satisfy its design contract until it hits thermal/overcurrent protection or the load drags the power supply rails down and it starts clipping, or maybe it can actually handle a full load into 4R, but this really depends on the circuit design and parameters. Speaker amps have low output impedance to keep damping factor low; you're not going to drop much voltage into the amp even at fairly high current.

This is why it's dangerous in the first place, as the amp can easily be operated outside its specified load point, and will happily do so until protection circuitry kicks in or it blows itself up.

But I think we basically agree. Be careful, do it anyway, and don't try to push it too hard.

 

[Soulstice]

Thanks for all the assistance.

Okay, one last question... ...just a bit confused after the last post....

Should I set the receiver to 6 ohms, or keep it at 8 ohms. REMEMBER, my two front speakers are 8 ohms KLA-9s... ...pretty high-end, albeit older.

I definitely don't want to damage those, or damage the receiver in drying to drive those at a lower ohms setting than expected by the speakers. lol


So, in the end, I'm asking... ...6 ohms or 8 ohms?

 

[keenan]

Set it to 6 ohms. It's not really going to affect your 8-ohm speakers other than possibly lowering the maximum output volume (and thereby protecting your amp from overcurrent into the 4 ohm ones).

It's generally safe to use higher impedance speakers than rated, but lower is riskier since it can result in unsafe currents in the amplifier.

 

[obobski]

yeah, set it to 6ohms

keenan:
the output voltage will be lower, only about a dozen or so amps will handle constant voltage across all impedances (Accuphase's M8000 is an example)

 

[Soulstice]

Thanks!

 

[golfer]

Soulstice .... just stumbled upon this thread don't know if you are following this any longer

Regarding those particular speakers .... I too have them.

I'm putting together a budget surround system for the GF and came across these for a heck of a price that was hard to ignore. Realizing they are 4 ohm ( nominal ) I them wired in series and used them for the center channel.
Must say for under $40 they sound pretty darn good for the center.... hard to beat for the price in my opinion.

Regarding your intended use ...... I'll throw in a couple of cents.

With mid-fi 2 channel amps they are generally designed for 8 ohm loads ( as already mentioned here speakers aren't a fixed value rather a nominal one. ) ...... however if the 2 channel device can accommodate a second pair of speakers to be attached ( switch with A , B - A&B ) then using A&B puts the 2 sets in parallel.

When you have 2 sets that are rated at 8 ohm ( nominal ) then the amp section is seeing a 4 ohm load. Generally speaking this isn't much of an issue since most equipment can handle this. Often the owner's manual will provide information as what impedance of speakers can be hooked up. If they don't specifically say it then the specs may indicate this buy showing rating at 8 ohm and 4 ohm .... for example. Or the back of the unit will be labeled near the speaker connections 4 - 8 ohms. This indicates the amp section is stable with either of those loads. In some rare cases you may run across 2 channel units requiring 16 ohm speakers if 2 sets are being used.
It's not a good idea to deviate from the unit's recommendation.

However , in your case having the main set rated at 8 ohms and the remotes rated at 4 ohm putting these in parallel you end up with about 2.67 ohm load on the amp. It seems you realize this isn't a good thing .... which it isn't.

Without getting into a lengthy ( more than I'm doing now ) and detailed discussion as to speaker reactance .... electrical dynamics of the amps ..... sonic balance , etc. ...... personally I would recommend for the cost of the speakers buy another set and wire them in series so you end up with 8 ohm impedance on the L&R remotes.
This would be the cheaper and better solution than messing around with adding the proper high wattage resistors. Besides ..... using the resistors creates it's own issues that results in disappointing results.

As for the 6-8 ohm switch ..... when placed in the 6 ohm position this drops the rail voltage internally for the amp section. What this will do is lower the dynamics and cause clipping sooner.

 

[Soulstice]

Just came across your response now.

I've been operating with the Yamaha set to 6 Ohms for months now, and I've had pretty good results.

I'm aware of the issues you indicated, but I did not want to blow out my unit by leaving it in 8 Ohms mode.

In terms of picking up a second set and wiring them in series, what is the best way to accomplish this? Should I use electrical twists, similar to wiring a light-switch, or should I solder the connections.

 

[jfnirvana292]

Well, I dont know much about audio, but if they are dual voice coil i think you can rewire them to be like 12 ohms...

 

[htpc_user]

In my younger years I used to do so much crap that would cause most people to cringe. Chances are using a 4 ohm speaker with a receiver is not going to hurt it, unless you're going to turn it to MAX all the time. To me, there's always the "right" way to do something and then there's the real world. I think a lot of times we get too caught up in the "specs".

I don't know how you can damage your equipment by running speakers in series. If you run two 4-ohms in series to make 8, your receiver just "sees" it as an 8-ohm load; it's one speaker as far as it's concerned. I also see no problem with using resistors as you said to make it an 8 ohm load. The only thing is that you'll be wasting a lot of the energy.

Let's say you're dealing with the left speaker(s). If you want to run your speakers in series, run the wire from the positive on the receiver to the positive on Left speaker (A), run the negative from the receiver to the negative on Left Speaker (B), then run a wire from Left speaker (A) negative to Left speaker (B) positive. Then repeat for the right side. I'm assuming that you want to run a total of 4 speakers in the surround so that you get 8 ohms on both sides?