Can We Pair 4 Ohms Speakers With 6 Ohms AVR?

[odyssey]

Am not sure why this is turning out to be such a controversial topic. The entire idea is quite simple - the amp power section is capable of driving a load (speaker) of a certain type - with certain specs. Obviously its not that if one deviates from it slightly, the amp is going to blow or the speaker. In fact the speaker blowing is highly unlikely, the amp going into overheating or thermal cutoff is more likely. This ALSO DEPENDS on volume that you are playing the system at - why? Since the overall power delivery has to be much higher to the speaker. So at what point does one say that so and so speaker is not recommended - its hard to say, but one has to draw the line somewhere. After all if an AVR is rated at 6 to 16 ohms, all its saying to me is that is where the amp is designed at and rated to be run at. If you run it at 4 ohms, will it run, sure but there is no certainity about how quickly it can heat up or how well it can drive it. If any of you have noticed, with cheap systems available in roadside shops, as you turn up the volume, sometimes the amp switches off and comes on when the volume is turned on - thats exactly whats happening here - thermal cutoff - the load is too hard to drive at that power. It does not matter if its a branded speaker or not, apart from the impedance curve, the phase complexity matters as well. This information in general is not very easy to get.
The simplest advice to the OP is this - if you have the AVR and need to buy the speakers, take it with you to the store and try it out, if you already have both the AVR and the speakers, nothing much to do dont think too much unless you have or hear an obvious problem

cheers

 

[prankey]

Am not sure why this is turning out to be such a controversial topic. The entire idea is quite simple - the amp power section is capable of driving a load (speaker) of a certain type - with certain specs. Obviously its not that if one deviates from it slightly, the amp is going to blow or the speaker. In fact the speaker blowing is highly unlikely, the amp going into overheating or thermal cutoff is more likely. This ALSO DEPENDS on volume that you are playing the system at - why? Since the overall power delivery has to be much higher to the speaker. So at what point does one say that so and so speaker is not recommended - its hard to say, but one has to draw the line somewhere. After all if an AVR is rated at 6 to 16 ohms, all its saying to me is that is where the amp is designed at and rated to be run at. If you run it at 4 ohms, will it run, sure but there is no certainity about how quickly it can heat up or how well it can drive it. If any of you have noticed, with cheap systems available in roadside shops, as you turn up the volume, sometimes the amp switches off and comes on when the volume is turned on - thats exactly whats happening here - thermal cutoff - the load is too hard to drive at that power. It does not matter if its a branded speaker or not, apart from the impedance curve, the phase complexity matters as well. This information in general is not very easy to get.
The simplest advice to the OP is this - if you have the AVR and need to buy the speakers, take it with you to the store and try it out, if you already have both the AVR and the speakers, nothing much to do dont think too much unless you have or hear an obvious problem

cheers

Absolutely, that is what we intend to communicate here instead of increasing the complexity of the matter. Such characteristics as you have mentioned and many of us have highlighted in earlier posts - just because the speaker says minimum impedance is 4 ohm, does NOT make it a bad choice for the amp. There are many practicalities applied and the added distortion due to impedance mismatch (during operating points where it dips to 4 ohms) might not be more than 1 or 2% max (unless there is a resonance happening at those frequencies - which CAN happen at 6 ohm and higher load as well).

Amp is saying it is BEST to connect a load with NOMINAL impedance of 6 to 16 ohms. Speaker is telling that it does have a NOMINAL impedance of 6 ohm where impedance can go as low as 4 ohm. It does not say how high can it get (it might go beyond 16 ohms as well at certain frequencies!). So there is nothing much to derive from such specs than to UNDERSTAND that when the impedance drops to 4 ohm during operation, there might be added distortion (can be unnoticed to many). This distortion may exist for a speaker which quotes its nominal impedance as 8 ohm and higher as well!

As indicated by Joshua, if there is impedance mismatch, power transfer might not be accurate and efficient as every amp is capable of delivering a particular voltage with a specific current drain capacity at a particular load impedance. This is where we talk of "matching" speakers with amp as some speakers perform better on an amp than others. Again, this discussion is beyond the OP's question who is just asking us if there will be an "issue" when the speaker says minimum impedance is 4 ohm (which will TYPICALLY ALWAYS be the case for a 6 ohm speaker). So, to answer him, there should not be any based on those specs.

 

[ShaQ.Blogs]

I am not going to even try replying post #17 & #18.
jls001 & odyssey put it across right again.

At no point is anyone saying that the receiver is going to blow or tweeter will. The key here is, it is not recommended! So wise up.
Like someone else had replied in a different forum to the OP. It's better to be safe than sorry.

To the OP:
I am not trying to *scare you* here. Just be aware, there is a risk, as you are in the not recommended zone. The matching is not as good as it can be so you can play without worries. It might work well, and it might not. Too many dependent factors to put one's foot down and say this is what is gonna happen. One advantage you have is that the PSB B6 does not have a scary impedance/phase chart. So it is relatively easier load to drive.

But still, to be on safer side, be a little careful on the volume knob. I believe a -10dB from reference levels should leave you with sufficient headroom. If you have an ear, which can scrutinize distortion, then let your ear be the guide. (I decided not rely on this, so I matched it well)

 

[ShaQ.Blogs]

here we go again...Looks like post #22 (prankey) will never get the point.
Hopefully this will make this... I know everything band wagon to go silent! Finally!!

I had written to denon customer service a while back based on a different question. (pls dont write to them for every small question, research first. They wont support us in future if we flood them with questions in the amateur league).

To Denon:

I am exploring the option of buying a denon receiver from the US & import it to a different country. We have a different power supply standard as compared to the US. Hence I require to use a stepdown convertor. The convertor needs to convert, 220V - 50Hz to 110V - 60Hz.

Hence my question is,
1. If I use a stepdown convertor to convert the voltage from 220V to 110V, would the 50Hz frequency cause any problems which are different from 60Hz.

I intend to use the following front speakers with the Receiver.
PSB Speakers
It is recommended to use a 4? capable amplifier.

Note: I haven't decided on which particular model to purchase yet.

Denon's Reply: (Please read...in Red)

We cannot support the use of a step down transformer. The frequency difference should not cause damage to the unit however we can make no promises when converting it for a power source it is not designed for. This unit may be able to drive a 4 ohm speaker however it is only rated for 6-16 ohms, therefore I cannot recommend using speakers that are lower than 6 ohms.

 

[avidyarthy]

So,

for laymen like the most of us here, a higher wattage amp is to be coupled to 'relatively' lower wattage speakers, if one has a tendency to play louder than usual, in such a scenario.

Even then, there is no need to jack the volume knob to the extreme 'clockwise' position. To remain safe, a mid position on the volume knob is more than sufficient to remain safe.

 

[ShaQ.Blogs]

So,

for laymen like the most of us here, a higher wattage amp is to be coupled to 'relatively' lower wattage speakers, if one has a tendency to play louder than usual, in such a scenario.

Even then, there is no need to jack the volume knob to the extreme 'clockwise' position. To remain safe, a mid position on the volume knob is more than sufficient to remain safe.

No. Watts are over rated. It is not as simple as matching watts of amp with watts of speaker, or a 6 ohm capable amp to a 6 ohm load. These are reactive loads. With frequency impedance & phase both change. Both together need to be analyzed. Do not always take what a manufacturer recommends. Sometimes if a manufacturer says speaker is a 6 ohm load, it's advised to consider it as a 4 ohm load. Of course, analysis of the impedance & phase chart can be a better analysis. But again, one needs to consider that these measurements are not perfect! Currently it is not possible to get *exact measurements* due to multiple constraints & challenges faced while measuring. But, by no means does it mean the measurements cant be relied upon. They are accurate to a large extent.

 

[avidyarthy]

When it comes to the wattage of the amps, there may be a way out ...

Buyers need to check the instruction manual of the amp before buying it. There is always a column of the spec sheet showing watts/channel in different modes, such as:

- x watts/ch: 1 Hz (@ 8 ohms or 6 ohms)
- y watts/ch: 20 Hz to 20 KHz (@ 8 ohms or 6 ohms)
- z watts/ch: 20 Hz to 20 KHz (@ 4 ohms)

Agreed, most manufacturers never say (or mean) that all channels working together would be provided with the same wattage ... thats the catch.

Some (high-end models) AVRs do provide what they say, of course .... Some of those AVRs/amps are indeed heavy !!!! Something, that kind of guarantees high current capabilities to drive low impedance speakers.

 

[yrk1969]

One advantage you have is that the PSB B6 does not have a scary impedance/phase chart. So it is relatively easier load to drive.

But still, to be on safer side, be a little careful on the volume knob. I believe a -10dB from reference levels should leave you with sufficient headroom. If you have an ear, which can scrutinize distortion, then let your ear be the guide. (I decided not rely on this, so I matched it well)

Why don't you share the chart so that we can also learn?

I had written to denon customer service a while back based on a different question. (pls dont write to them for every small question, research first. They wont support us in future if we flood them with questions in the amateur league).

I am curious about your questions to Denon. Did you really expect Denon to reply otherwise?

"Hey we rate them at "x", but feel free to run them at "y", you can send it back to us for warranty cover if it fails."

Do you really think this is how manufacturers in general work?

 

[avidyarthy]

Agree with you 100% yrk.

No manufacturer would want to shoot themselves on their own foot.

 

[prankey]

here we go again...Looks like post #22 (prankey) will never get the point.
Hopefully this will make this... I know everything band wagon to go silent! Finally!!

I had written to denon customer service a while back based on a different question. (pls dont write to them for every small question, research first. They wont support us in future if we flood them with questions in the amateur league).

To Denon:


Denon's Reply: (Please read...in Red)

In one sentence - You are trying to prove here that an amp optimized for a 6 ohm load impedance has to be paired with an speaker which do not drop impedance below 6 ohm (which may not be true even for a 32 ohm speaker!).

Dude, we know that Onkyo is particularly an Amp/AVR brand more "optimized" for a 6 ohm speaker which will most certainly have impedance curve going below 4 ohm including the entire range of "matched" Onkyo speakers! Will those MICRO SECONDS where the impedance drop below 6 ohms make such difference? We just need to apply our BRAINS and COMMON SENSE instead of getting into such discussion specific to this speaker pair's impedance curve. As I have tried to highlight in my earlier posts, there are several factors needing attention when choosing the right speakers and NOMINAL IMPEDANCE is one of them, however minimum impedance of these speakers are not at all a great concern for the OP to be worried about. Virtually every amp capable of supporting 6 ohm should be able to DRIVE a NOMINAL impedance of 4 ohms as well without much issues EXCEPT loss of sound quality due to added bit of MILD distortion as COMPARED to SIMILARLY SPEC'd speakers with better impedance matching. Talking of them going kaput has MORE to do with their build quality and power handling capacity than JUST the impedance mismatch. Amp will not MAGICALLY get OVERPOWERED to destroy itself (despite having limited power supply with limited current drain capacity) or speakers destroying themselves because of impedance mismatch. I can not be more crisp than this.

I can see you going TOO MUCH at the face value of a product and support. How do you expect DENON to respond to your question? I am amazed to learn that you want to take recommendation from the manufacturer just based on the impedance characteristics (there are several other key parameters to be matched other than impedance).

I sincerely appreciate you demonstrating your WISDOM on the matter of "impedance". However, you still relying on manufacturer's recommendations and publishing it is something rather surprising.

 

[prankey]

Agree with you 100% yrk.

No manufacturer would want to shoot themselves on their own foot.

+1, pasting a "copy and paste" (STANDARD, EXPECTED) reply from manufacturer will not prove anything. I find it tough to respond to such posts and personalities.

 

[ShaQ.Blogs]

I am curious about your questions to Denon. Did you really expect Denon to reply otherwise?

"Hey we rate them at "x", but feel free to run them at "y", you can send it back to us for warranty cover if it fails."

Do you really think this is how manufacturers in general work?

Good point!
Look at this from another perspective, if the amp was capable of playing the more demanding 4 ohm load with ease, why wouldnt they say yes and also rate it too as 4 -16 instead of 6-16? It would sell better right?

This is where your previous post hit the nail right on its head!!

Some (high-end models) AVRs do provide what they say, of course .... Some of those AVRs/amps are indeed heavy !!!! Something, that kind of guarantees high current capabilities to drive low impedance speakers.

This costs more money, thats the catch.
In one earlier post I had mentioned how manufacturers pack more features and compromise on some others. This is what the Mass Market desires. The current demand is usually *that something else*, on top of latest Audessey version and blah blah which is compromised.

 

[yrk1969]

Good point!
Look at this from another perspective, if the amp was capable of playing the more demanding 4 ohm load with ease, why wouldnt they say yes and also rate it too as 4 -16 instead of 6-16? It would sell better right?

Why?

1. Maybe it will blow up (hope not for the OP )
2. Maybe they do not want to spend time and money on testing and certifying it with 4ohm loads.
3. ... no idea

So will it blow up?

Here's what my Onkyo 705 manual says:

"North American models: Only connect speakers
with an impedance of 6 ohms or higher. If you use
speakers with a lower impedance, and use the amplifier
at high volume levels for a long period of time, the
built-in protection circuit may be activated."

and further on the same page for other stuff...

"Be careful not to short the
positive and negative wires.
Doing so may damage the AV
receiver/AV amplifier."

and...

"Make sure the metal core of the
wire does not have contact with
the AV receiver/AV amplifiers
rear panel. Doing so may damage
the AV receiver/AV amplifier."

and...

"Dont connect more than one cable to each speaker
terminal. Doing so may damage the AV receiver/AV
amplifier."

Notice the difference in first para vs others? The other para exactly points out the potential damage which may occur. While the first one only mentions about protection circuit kicking in at at high volume levels and that too for a long period of time.

Please feel free to make your conclusions.

 

[yrk1969]

The simplest advice to the OP is this - if you have the AVR and need to buy the speakers, take it with you to the store and try it out, if you already have both the AVR and the speakers, nothing much to do dont think too much unless you have or hear an obvious problem

To the OP: This is probably the best advice, I would take it if it were to me.

 

[prankey]

Good point!
Look at this from another perspective, if the amp was capable of playing the more demanding 4 ohm load with ease, why wouldnt they say yes and also rate it too as 4 -16 instead of 6-16? It would sell better right?

Any amp for that matter can handle any type of load to an extent. The nominal impedance range is mentioned for a reason - That is the OPTIMUM RECOMMENDED NOMINAL IMPEDANCE of the amp and as long as we us a 6 Ohm NOMINAL IMPEDANCE speakers, we are good!!!

 

[prankey]

To the OP: This is probably the best advice, I would take it if it were to me.

That would also ensure that you are getting what you were looking for (SQ in terms of frequency response, sensitivity and THD).

 

[naren2512]

@ avidyarthy, @ prankey, @ jls001 , @ odyssey, @ yrk1969 , @ ShaQ.Blogs

Thank you all very much for sharing your knowledge / experience and trying to guide me in right direction. At some point the discussion had got into near argument state ( which was not good ) but I really appreciate your help.

I now understand that :

1) The optimum solution / safe option - is to use the AVR that supports the minimum impedance of the speakers

2) However if there is slight difference like it is in my case ( speakers min impedance 4 ohms and AVR impedance 6-16 ohms) then it may result in sound distortion at high volume and the AVR may get hot if volume is not brought down immediately also it may result in AVR getting auto shut down as a safety measure by the AVR circuit but this all may not happen if the volume is kept not very high

3) The chances of speakers getting damaged are very very rare - Also personally I haven't heard of any ones speakers getting damaged. So I guess i dont need to worry too much about this.


So this is what I am going to do now :

1) I am going to buy the same speakers I have liked i.e PSB Image and will pair them with Onkyo 608 and will remember not to play them at high volume. ( I had demoed them with Onkyo 608, Denon 1911, Marantz 6007 AVR and they sounded almost same with all of them may be little better with Marantz)

2) I will try to a good quality 1KV Step down, for my AVR which should be sufficient as the AVR requires max 700 watts.

3) I will use PSB with Onkyo for a few months, incase I dont like the pairing or cant play my HTS at the volume i woudl like to ( due to distortion ) then i will try to buy another AVR ( which will be either Marantz or NAD 747 ) and sell off my Onkyo 608...

4) I will try to use speaker wire of good gauge ( I think 14 gauge wire should be good enough )


I will keep you all posted as to how I find the performance of my HTS or come back to you with questions etc incase I have a problem with this pairing ( hope I do not come back for this reason !! )

Once again Thank you all for all the help ...

Regards,
Naren

 

[prankey]

Naren - Few minor caveats to your understanding:

If you connect speakers with nominal impedance less than 6 ohm, mild distortion will be heard at EVERY VOLUME LEVELS due to impedance mismatch (random voltage drops at peaks to cover for the extra current drain), however you need not worry about it as your speakers have nominal impedance of 6 ohm and increased distortion may occur only during those frequencies when the impedance drops below 6 ohm.

For least distortion and current drain, using higher impedance speakers might be better, but it will significantly reduce the power output of the amp while keeping it cooler.

Its quite normal for the AVR to become VERY HOT during VERY HIGH volume levels which we usually can't sustain at home anyway. This will happen even if you connect a speaker with minimum impedance of 6 ohm. Hence, its not a big issue to be worried about, however you should always ensure that the AVR has enough "breathing" space and never cover its vents with cloths, etc. This will ensure that the AVR do not heat up unnecessarily.

Your Amp may NEVER drain more than 300 watts of power (as it has huge capacitors to store excess power needed during high volume, full load operation). So a 1kVA transformer will always be ample as the one inside the AVR may not even be a 300VA (even when it outputs 700Watts of RMS power).

Last but not the least, congrats on your decision and hope the purchase keeps you happy for years to come.

 

[venkatcr]

I am not sure how this can be done, but I am sure there is a way to increase the impedance of speakers without affecting other features. Since Naren likes the PSBs so much, this may be the best option.

Cheers

 

[naren2512]

Thanks Venkat,

I had read about something similar at below link, but this product is expensive so buying another AVR may be cheaper unless there are some other similar products to increase the impedance at affordable price

ZEROs

Regards,
Naren