A question about impedance

DJM1976

Active Member
Hi all, I am sitting here really confused over impedance as have been looking at speakers due to my dated Kenwood satellites being too quiet., so thought it would be best to ask. I have a Yamaha Musiccast RN303D and in the manual it clearly states that speakers need to be a minimum of 8 ohms to avoid overheating. However suppliers are bundling the same receiver with the Q Acoustics Q3010i which when looking at the specifications it states that the speakers have an average impedance of 6 ohms. So now this brings me to question why a reputable supplier like Peter Tyson is doing this bundle, or am I looking at this completely wrong ?.

Any advice / thoughts on this would be greatly appreciated

Many thanks
 

RBZ5416

Distinguished Member
Given their web site says this, probably best to ask them for clarification.:

1624014561920.png


Looks wrong as the power into 4 ohm would normally be higher than into 8, so I suspect a misprint.

Although a 6 ohm load isn't likely to be an issue in any case unless it dips significantly below that. Speaker impedance is usually only spec'd as a nominal value.
 

DJM1976

Active Member
Given their web site says this, probably best to ask them for clarification.:

View attachment 1529391

Looks wrong as the power into 4 ohm would normally be higher than into 8.

Although a 6 ohm load isn't likely to be an issue in any case unless it dips significantly below that. Speaker impedance is usually only spec'd as a nominal value.
Thank you for the reply, i will get in touch with Yamaha themselves to make sure this in the manual is correct.
D3F0B891-C971-4712-99FB-246AA55076E2.jpeg
 

RBZ5416

Distinguished Member
The specs at the back of the manual are even more confusing, implying that it supports down to 2 ohm. Doesn't help either when they mix & match differing terms for power.

1624015310164.png
 

RBZ5416

Distinguished Member
These companies really do like to make things confusing especially for newbies into audio.
I'm afraid it's all an attempt to print the biggest "power" number & is largely BS. Most of the more reputable manufacturers will only quote RMS figures with very low distortion (fractions of 1%). One of those Yamaha figures was based on 10% distortion. 🙄
 

DJM1976

Active Member
I'm afraid it's all an attempt to print the biggest "power" number & is largely BS. Most of the more reputable manufacturers will only quote RMS figures with very low distortion (fractions of 1%). One of those Yamaha figures was based on 10% distortion. 🙄
Wow now that I wasn’t expecting especially in the manual it also clearly states that overheating may occur if you use less than 8ohms. This is all very misleading and I guess it is also a loophole for them to avoid repairs under warranty if the unit burns out from using speakers which they recommend against using.
 

Cliff

Distinguished Member
Wow now that I wasn’t expecting especially in the manual it also clearly states that overheating may occur if you use less than 8ohms. This is all very misleading and I guess it is also a loophole for them to avoid repairs under warranty if the unit burns out from using speakers which they recommend against using.
Can the impedance be switched?
 

John7

Well-known Member
Wow now that I wasn’t expecting especially in the manual it also clearly states that overheating may occur if you use less than 8ohms. This is all very misleading and I guess it is also a loophole for them to avoid repairs under warranty if the unit burns out from using speakers which they recommend against using.

No it doesn't. It says "excessively" low impedance which is a different thing!

6 Ohm speakers will be fine with an amp rated at a nominal 8 Ohms.

Speaker impedance is not a fixed value, it varies with frequency and power level (temperature in the chokes/coils). All speakers present a varied impedance to the amp in use. I believe what Yamaha are implying is to not connect speakers with a 2 Ohm impedance as it will cause the amp to get hotter than design. Lower impedance allows more power to flow, more power = heat generation.
 

DJM1976

Active Member
No it doesn't. It says "excessively" low impedance which is a different thing!

6 Ohm speakers will be fine with an amp rated at a nominal 8 Ohms.

Speaker impedance is not a fixed value, it varies with frequency and power level (temperature in the chokes/coils). All speakers present a varied impedance to the amp in use. I believe what Yamaha are implying is to not connect speakers with a 2 Ohm impedance as it will cause the amp to get hotter than design. Lower impedance allows more power to flow, more power = heat generation.
Thank you for explaining that to me, it makes much more sense now.
 

Paul7777x

Distinguished Member
First of all, I’d ignore most everything about impedance.

Daft as it may seem.

Speaker manufacturers figures are worse than useless. There really is no attempt to offer a graph with an impedance curve for 99% of speakers so any claimed figure is no use.

The minimum impedance and where it sits in the frequency curve is what matters and is rarely given. The ‘nominal’ impedance figure is a waste of ink.

The fact that the Yamaha claims its power output at 8 Ohms from 40Hz is a dead giveaway. It should be from 20Hz.

But it’s not as bad as it first seems.

In reality I suspect a more realistic output to be around 60-70W into 8 Ohms with the usual measuring stick. That’s not at all bad.

Then checking it’s Dynamic power makes more sense.

The fact that Yamaha even bother to quote a 2 Ohm figure is very encouraging.

I’d bet a big pile of cash that the Yamaha will be perfectly happy driving any speaker in its price class.

Certainly the QAs won’t present any significant problems.
 

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