Speaker Impedance

[Phil J N.Z.]

I have a new Marantz SR7015 on order and read in the manual that you can change the speaker impedance to match your speakers the default is 8 Ohms, the only speaker in my set up that matches is my centre speaker, the rest are 6 Ohms.

Question is should I change it as I have read elsewhere that I should just leave it as is?

 

[TLS Guy]

I have a new Marantz SR7015 on order and read in the manual that you can change the speaker impedance to match your speakers the default is 8 Ohms, the only speaker in my set up that matches is my centre speaker, the rest are 6 Ohms.

Question is should I change it as I have read elsewhere that I should just leave it as is?

Leave as is.

 

[lovinthehd]

You might like this article but as said, just leave it at the higher impedance setting. https://www.audioholics.com/audio-amplifier/impedance-selector-switch-1

 

[Phil J N.Z.]

OK so why have the ability to change it then, am a bit worried about this as my old Marantz SR6007 did not have this ability and it fried my centre channel on the AVR, it was the only speaker 8 Ohms all the other are 6.

 

[lovinthehd]

OK so why have the ability to change it then, am a bit worried about this as my old Marantz SR6007 did not have this ability and it fried my centre channel on the AVR, it was the only speaker 8 Ohms all the other are 6.

The article linked discussed that. What speaker was it and how loud were you at?

 

[TLS Guy]

OK so why have the ability to change it then, am a bit worried about this as my old Marantz SR6007 did not have this ability and it fried my centre channel on the AVR, it was the only speaker 8 Ohms all the other are 6.

The article Lovin linked explains it well. As you can see speaker impedance is a curve. There are also phase angles which affect current draw. The problem is a speaker manufacturer can claim any impedance they like, and few are remotely honest. But most are actually four ohms, a few small bookshelf speakers excluded.
The switch just limits the voltage available and therefore current and power.

Essentially all amps should be able to power a four ohm load without issue. Unfortunately few can now. That is actually a disgrace. In my view any amp needs to be four ohm stable as part of its basic design and specification. If not it is suspect and not fit for purpose.

 

[Phil J N.Z.]

The article linked discussed that. What speaker was it and how loud were you at?

Well it did not die all of a sudden it was a gradual slow death of the centre channel, I know it was the power amp and not the processor board as I took an RCA lead and connected it to the pre-amp out to another amplifier I had sitting around and it worked fine, Speaker connected in question is a B&W HTM62 we don't wind the volume flat out no where near it.

 

[Phil J N.Z.]

The article Lovin linked explains it well. As you can see speaker impedance is a curve. There are also phase angles which affect current draw. The problem is a speaker manufacturer can claim any impedance they like, and few are remotely honest. But most are actually four ohms, a few small bookshelf speakers excluded.
The switch just limits the voltage available and therefore current and power.

Essentially all amps should be able to power a four ohm load without issue. Unfortunately few can now. That is actually a disgrace. In my view any amp needs to be four ohm stable as part of its basic design and specification. If not it is suspect and not fit for purpose.

Thanks, I read the article Lovin sent but if am honest it was way over my head, seems to be aimed at people who are qualified electronic techs.

 

[lovinthehd]

Well it did not die all of a sudden it was a gradual slow death of the centre channel, I know it was the power amp and not the processor board as I took an RCA lead and connected it to the pre-amp out to another amplifier I had sitting around and it worked fine, Speaker connected in question is a B&W HTM62 we don't wind the volume flat out no where near it.

Center channel speakers are often very much compromises, and B&W speakers are often a poor design.

If you were using a power amp on the pre-outs of the avr, then it has nothing to do with the avr.

 

[Phil J N.Z.]

Center channel speakers are often very much compromises, and B&W speakers are often a poor design.

If you were using a power amp on the pre-outs of the avr, then it has nothing to do with the avr.

I was not using a power amplifies, I was only testing it using the pre amp out to see if it was the processor board or the power amplifier for that channel. The fault lies in the AVR.

 

[lovinthehd]

M

I was not using a power amplifies, I was only testing it using the pre amp out to see if it was the processor board or the power amplifier for that channel. The fault lies in the AVR.

Thanks for the clarification. The fault still always lies with the user's choice of equipment and spl levels, tho. A power amp may well be the better way to go, aside from changing speakers....

 

[everettT]

Well it did not die all of a sudden it was a gradual slow death of the centre channel, I know it was the power amp and not the processor board as I took an RCA lead and connected it to the pre-amp out to another amplifier I had sitting around and it worked fine, Speaker connected in question is a B&W HTM62 we don't wind the volume flat out no where near it.

Amplifier failure was common in a couple of marantz model years. I had a friend loose his center channel twice with the 6010, one was covered under warranty and the other he went to an external amp. His center was an absolute benign load and failed twice. He wasn't running anything complex the first time, a 5.1 setup, the second time he had a rear "bouncy" Atmos added. The B&W speakers all suffer from low impedance in the power band and your's being a 2 way didn't help you.

 

[Verdinut]

IMO, speakers with impedance dips below 3 ohms and weird phase angle curves are just poor designs. It still only proves that expensive stuff is not necessarily a better made product.

 

[Phil J N.Z.]

Amplifier failure was common in a couple of marantz model years. I had a friend loose his center channel twice with the 6010, one was covered under warranty and the other he went to an external amp. His center was an absolute benign load and failed twice. He wasn't running anything complex the first time, a 5.1 setup, the second time he had a rear "bouncy" Atmos added. The B&W speakers all suffer from low impedance in the power band and your's being a 2 way didn't help you.

Well I cannot afford a power amp, besides my old SR6007 was rated at 110 Watt per Channel where the new SR7015 I have is rated at 125 watts at 8 Ohms and 165 watts at 6 Ohms.
Interesting sidebar to this is my first Marantz was an SR6005 and I had nothing but trouble with it, I would get a loud POP through the speakers and it would go in to protected mode, it want back for repair 4 times and they could find nothing wrong, a tech even came to my home and found no issues with my installation, later after dong some digging on the net it was called the Marantz POP of death and there were recorded issues with other people having the same issue, here in NZ we have the "Consumers Guarantee Act" and it protects us from faulty goods like this, they took the unit back and replaced it with the SR6007 and up until now I have had no issues at all.

 

[TLS Guy]

Well I cannot afford a power amp, besides my old SR6007 was rated at 110 Watt per Channel where the new SR7015 I have is rated at 125 watts at 8 Ohms and 165 watts at 6 Ohms.
Interesting sidebar to this is my first Marantz was an SR6005 and I had nothing but trouble with it, I would get a loud POP through the speakers and it would go in to protected mode, it want back for repair 4 times and they could find nothing wrong, a tech even came to my home and found no issues with my installation, later after dong some digging on the net it was called the Marantz POP of death and there were recorded issues with other people having the same issue, here in NZ we have the "Consumers Guarantee Act" and it protects us from faulty goods like this, they took the unit back and replaced it with the SR6007 and up until now I have had no issues at all.

I know your center speaker is rated at 8 ohms, but it is not an 8 ohm speaker and almost certainly 4 ohms or close.

Unfortunately I can not find an impedance curve or phase angles for that speaker. However when I dig up a B & W file on that speaker they state that the minimum impedance of the speaker is 4.3 ohms. However a good rule of thumb is that the impedance is the minimal impedance plus 10%. So that would make the speakers about 4.7 ohms. The next issue is that you have already had one receiver have the center channel blow driving that speaker. What concerns me is that amps in receivers have become less tolerant of four ohm loads than older ones. Manufacturers of receivers now seldom quote specifications into four ohm loads. This is appalling as center speakers are almost always four ohm as they always have two bass mids in parallel.
I had not realized that manufacturers had returned to putting an impedance switch on receivers again. That is a bad omen.
Looking at this again, I'm inclined to recommend that you do use the four ohm switch in view of your past history. This comes with a huge downside though as it will seriously reduce the power available from your receiver.
Unfortunately your best option by far is using external power amplification. It is for all these reasons that I personally do not use receivers, never have and never will. I use, and have used, only AV preamps connected to power amps. My experience with reliability has been excellent. I am certain this has been the cheapest solution for me in the long run. But then I have a bias to the long rather than the short view.

 

[Phil J N.Z.]

I know your center speaker is rated at 8 ohms, but it is not an 8 ohm speaker and almost certainly 4 ohms or close.

Unfortunately I can not find an impedance curve or phase angles for that speaker. However when I dig up a B & W file on that speaker they state that the minimum impedance of the speaker is 4.3 ohms. However a good rule of thumb is that the impedance is the minimal impedance plus 10%. So that would make the speakers about 4.7 ohms. The next issue is that you have already had one receiver have the center channel blow driving that speaker. What concerns me is that amps in receivers have become less tolerant of four ohm loads than older ones. Manufacturers of receivers now seldom quote specifications into four ohm loads. This is appalling as center speakers are almost always four ohm as they always have two bass mids in parallel.
I had not realized that manufacturers had returned to putting an impedance switch on receivers again. That is a bad omen.
Looking at this again, I'm inclined to recommend that you do use the four ohm switch in view of your past history. This comes with a huge downside though as it will seriously reduce the power available from your receiver.
Unfortunately your best option by far is using external power amplification. It is for all these reasons that I personally do not use receivers, never have and never will. I use, and have used, only AV preamps connected to power amps. My experience with reliability has been excellent. I am certain this has been the cheapest solution for me in the long run. But then I have a bias to the long rather than the short view.

Now you have me worried ad the documentation that came with the Speaker says nominal impedance 8 Ohms, I have just checked the manual for the old SR6007 and there is no ability to change the speaker impedance in that AVR but says The speaker impedance should be from 6 to 8 Ω.
in the manual for the SR7015 there are 3 settings as below.

Carry out the following settings when using a speaker with an impedance of 4 – 6
Ω/ohms.
1. Press and hold the main unit’s ZONE SELECT and STATUS at the same time
for at least 3 seconds.
“zVideo Format <NTSC>” appears on the display.
2. Press i on the main unit three times.
“zSp. Impedance <8ohms>” appears on the display.
3. Use o or p on the main unit to select the impedance.
8ohms
(Default):
Select when the impedance for all of the
connected speakers is 8 Ω/ohms or over.
6ohms: Select when the impedance for any of the
connected speakers is 6 Ω/ohms.
4ohms: Select when the impedance for any of the
connected speakers is 4 Ω/ohms.
4. Press the main unit’s ENTER to complete the setting.

So can I ask you the question in how are you so sure that the B&W speaker is in fact 4 Ohms yet the information as printed and supplied by the makers say 8 Ohms.

I have just found this on the NET relating to this speaker in question as below.

Nominal impedance 8Ω (minimum 4.3Ω), so given this info should I assume it is in fact a 4 Ohms speaker???, why can manufactures not put the correct info with the goods?

Now I wonder is I have to re do all the speaker calibration all over again.

At the moment I have the AVR set at 6 Ohms.

 

[TLS Guy]

Now you have me worried ad the documentation that came with the Speaker says nominal impedance 8 Ohms, I have just checked the manual for the old SR6007 and there is no ability to change the speaker impedance in that AVR but says The speaker impedance should be from 6 to 8 Ω.
in the manual for the SR7015 there are 3 settings as below.

Carry out the following settings when using a speaker with an impedance of 4 – 6
Ω/ohms.
1. Press and hold the main unit’s ZONE SELECT and STATUS at the same time
for at least 3 seconds.
“zVideo Format <NTSC>” appears on the display.
2. Press i on the main unit three times.
“zSp. Impedance <8ohms>” appears on the display.
3. Use o or p on the main unit to select the impedance.
8ohms
(Default):
Select when the impedance for all of the
connected speakers is 8 Ω/ohms or over.
6ohms: Select when the impedance for any of the
connected speakers is 6 Ω/ohms.
4ohms: Select when the impedance for any of the
connected speakers is 4 Ω/ohms.
4. Press the main unit’s ENTER to complete the setting.

So can I ask you the question in how are you so sure that the B&W speaker is in fact 4 Ohms yet the information as printed and supplied by the makers say 8 Ohms.

At the moment I have the AVR set at 6 Ohms.

Because when I checked the data on the B & W website it said the minimum impedance is 4.3 ohms. Minimum impedance is much closer to actual impedance than what a manufacturer rates a speaker in their literature. They do this to avoid loosing sales. If you build a speaker with two bass mids it is hard for it not to be 4 ohms or close, as they are parallel wired. The real fault is with receiver manufacturers who cram far too many power amp boards in one case, and use output devices with poor ability to provide current. However if you do the above, and set to four ohms, then the current to the output devices is limited. The whole farce is a disgrace anyway you look at it. Only the 8 ohm setting allows the receiver to deliver its specified power.

Your best bet is to settle the issue by ordering this Dayton woofer tester. Connected to a computer this will allow you to see the impedance curve and phase angles. That will definitively settle the issue. Then you can do everyone a favor by posting the results here.

Here are the curves I got from a friends B & W speakers.

As you can see they are essentially four ohm speakers, but they were specked as 8. In this case it did not matter as he had potent external amps.

 

[Phil J N.Z.]

Because when I checked the data on the B & W website it said the minimum impedance is 4.3 ohms. Minimum impedance is much closer to actual impedance than what a manufacturer rates a speaker in their literature. They do this to avoid loosing sales. If you build a speaker with two bass mids it is hard for it not to be 4 ohms or close, as they are parallel wired. The real fault is with receiver manufacturers who cram far too many power amp boards in one case, and use output devices with poor ability to provide current. However if you do the above, and set to four ohms, then the current to the output devices is limited. The whole farce is a disgrace anyway you look at it. Only the 8 ohm setting allows the receiver to deliver its specified power.

Odd that Marantz says if you switch to 6 Ohms power is 165 watts, 8 Ohms is 125 Watts, is that wrong, there is no rated output for 4 Ohms.

 

[TLS Guy]

Odd that Marantz says if you switch to 6 Ohms power is 165 watts, 8 Ohms is 125 Watts, is that wrong, there is no rated output for 4 Ohms.

I just updated my last post to advise you buy a woofer tester, and settle the issue. If you set the amp to a lower impedance it can not increase the power. They don't give a four ohm spec. as they don't want you using 4 ohm speakers, but the fact is that you can not generally avoid it. It seems most consumers are prepared to tolerate this nonsense, including many members here. I say emphatically that I will not, and so avoid receivers like the plague.

 

[lovinthehd]

Odd that Marantz says if you switch to 6 Ohms power is 165 watts, 8 Ohms is 125 Watts, is that wrong, there is no rated output for 4 Ohms.

You are misunderstanding the spec let alone what Marantz is indicating.