[PHardy]

Hello everyone, this is my first thread to the forum. I am not the most technical in electronics. Usually I can find the answers to my questions by the search function. I have a old Denon AVC-3030 5.1 surround amplifier. I have front, center and rear 8 ohms speakers hooked up now, I just got a good deal on another set of 8 ohms speakers.

So here is my question. The amp spec.'s say Main speaker A or B = 6 to 16 ohms, A + B = 12 to 16 ohms. Can I hook up my new speakers and run A + B without damaging the amp? All four fronts are 8 ohms. If the answer is yes, then do I need to wire them one way or the other? Thanks for all and any help with this matter.

 

[jdsmoothie]

By running A+B, the 8 ohm speakers effectively become 4 ohm speakers. As long as you don't go beyond average volume, you should be fine. If you should drive the volume to high, the AVR will shut down and go in to Protection Mode prior to any harm coming to the AVR. Let it cool down for awhile then you can turn it back on. That would be the highest volume you can go in the future.

 

[John McCutcheon]

I hope you're not doing this thinking it will create 7.1 channel surround. The purpose of A and B mains is that some people prefer one set of mains for movies and another, "more musical", set for listening to stereo music.

 

[M Code]



Quote:
Originally Posted by jdsmoothie /forum/post/18235146


By running A+B, the 8 ohm speakers effectively become 4 ohm speakers. As long as you don't go beyond average volume, you should be fine. If you should drive the volume to high, the AVR will shut down and go in to Protection Mode prior to any harm coming to the AVR. Let it cool down for awhile then you can turn it back on. That would be the highest volume you can go in the future.

Incorrect for the Denon..

Some brand/models wire multiple loudspeakers in series and others in parallel..

The Denon is wired in series so the impedance to the amplifier is loudspeaker A + loudspeaker B which equals 16 Ohms. Also wiring loudspeakers in series has other pitfalls as well..

But to the audio design engineer the series method better protects the amplifier's output stage from seeing very low impedances such as

To my knowledge the only brands that provide the parallel loudspeaker switching configuration are HK & Rotel in their higher end products. The parallel configuration is more costly, requires a higher current power supply

and beefier output stage.


Just my $0.01..

 

[absolootbs]



Quote:
Originally Posted by M Code /forum/post/18241054


Incorrect for the Denon..

Some brand/models wire multiple loudspeakers in series and others in parallel..

The Denon is wired in series so the impedance to the amplifier is loudspeaker A + loudspeaker B which equals 16 Ohms. Also wiring loudspeakers in series has other pitfalls as well..

But to the audio design engineer the series method better protects the amplifier's output stage from seeing very low impedances such as

To my knowledge the only brands that provide the parallel loudspeaker switching configuration are HK & Rotel in their higher end products. The parallel configuration is more costly, requires a higher current power supply

and beefier output stage.


Just my $0.01..

not that i don't trust your knowledge m code (i know you have an abundance of it), but why then would they recommend a minimum A+B nominal impedance thats double the A or B minimum, if not because they're run in parallel and a nominal 6 ohm load is all they want you to throw at the receiver, with either configuration? if they're run in series, why wouldn't they specify A or B: 6 ohm min, A+B: 3 ohm min?

 

[M Code]



Quote:
Originally Posted by absolootbs /forum/post/18241132


not that i don't trust your knowledge m code (i know you have an abundance of it), but why then would they recommend a minimum A+B nominal impedance thats double the A or B minimum, if not because they're run in parallel and a nominal 6 ohm load is all they want you to throw at the receiver, with either configuration? if they're run in series, why wouldn't they specify A or B: 6 ohm min, A+B: 3 ohm min?

No you have it backwards..

When loudspeakers are connected in series it is A + B, when in parallel it is

A + B/2..


Just my $0.01..

 

[absolootbs]



Quote:
Originally Posted by M Code /forum/post/18241410


No you have it backwards..

When loudspeakers are connected in series it is A + B, when in parallel it is

A + B/2..


Just my $0.01..

no, you misunderstood me. i'm very familiar with how to calculate ohm loads. i wasn't referring to A+B as the equation for ohm load, i was referring to the notation on OP's receiver - A+B meaning running your A and B speakers at the same time. this would be as opposed to A or B, referring to running one set or the other.


edit: something just occured to me. i think you misunderstood me, but i think i misunderstodd the OP's receiver. i assumed A+B meant "A and B", meaning the receiver was saying that when running both sets at the same time, you should use a minimum of 12 ohm speakers. since 12 ohm in parallel would be a 6 ohm load, this seemed to indicate to me that they were in parallel since the minimum it wants on a single set of speakers is also 6 ohms. whereas upon rereading, i see that what the receiver says (A+B = 12 ohm) could mean that when running both sets together, the minimum total impedance should be 12 ohms, or, 6 ohms per speaker. this would be in keeping with what you said - that the A and B sets are run in series.

 

[PHardy]



Quote:
Originally Posted by John McCutcheon /forum/post/18240480


I hope you're not doing this thinking it will create 7.1 channel surround. The purpose of A and B mains is that some people prefer one set of mains for movies and another, "more musical", set for listening to stereo music.

John, that is exactly what I am trying to do. Also in all of the amps surround modes use can turn on and off the Main/Front "A" and "B" speakers. I just want to make sure that if I did have the A & B main speakers on at the same time nothing bad will happen.


Like I said I am not real good with all of the speaker and or impedance formulas.

 

[PHardy]



Quote:
Originally Posted by M Code /forum/post/18241054


Incorrect for the Denon..

Some brand/models wire multiple loudspeakers in series and others in parallel..

The Denon is wired in series so the impedance to the amplifier is loudspeaker A + loudspeaker B which equals 16 Ohms. Also wiring loudspeakers in series has other pitfalls as well..

But to the audio design engineer the series method better protects the amplifier's output stage from seeing very low impedances such as

To my knowledge the only brands that provide the parallel loudspeaker switching configuration are HK & Rotel in their higher end products. The parallel configuration is more costly, requires a higher current power supply

and beefier output stage.


Just my $0.01..

M Code, does this mean my 8 ohms speakers (if the do get turned on at the same time) will be OK? I do know that the amp will go into protection mode, but I do not want to damage my speakers.

 

[jdsmoothie]

As I implied in my first post, the A+B speaker posts are connected in "parallel" which would reduce your 8 ohm speakers to 4 ohm speakers. This is common to all Denon AVRs. The AVR will shut down before there is any damage to your speakers (and if you should hear the speakers clipping, you can just reduce the volume with no damage to the speakers if done in a timely manner). Although keep in mind that the same channel information going to the "A" speakers will go to the "B" speakers so you will not have a true 7.1 surround setup that you are apparently trying to create.

 

[PHardy]



Quote:
Originally Posted by jdsmoothie /forum/post/18243235


As I implied in my first post, the A+B speaker posts are connected in "parallel" which would reduce your 8 ohm speakers to 4 ohm speakers. This is common to all Denon AVRs. The AVR will shut down before there is any damage to your speakers (and if you should hear the speakers clipping, you can just reduce the volume with no damage to the speakers if done in a timely manner). Although keep in mind that the same channel information going to the "A" speakers will go to the "B" speakers so you will not have a true 7.1 surround setup that you are apparently trying to create.

Thanks jdsmoothie, that is what I need to know. I am not trying to get 7.1 setup, I just wanted to know that with this setup, if both the A + B speakers were on, nothing bad will happen to the amp or speakers.


Do I wire them in any certain way? or can I just wire the speakers individually to their assigned post? thanks.

 

[jdsmoothie]

Just connect the extra set of speakers to the "B" posts just as you have your main fronts connected to the "A" posts. Then you can use the SPEAKERS selector switch to select either A, B, or A+B as you choose.

 

[PHardy]

Thanks jdsmoothie, that helps a lot.

 

[Speedskater]



Quote:
Originally Posted by M Code /forum/post/18241410


No you have it backwards..

When loudspeakers are connected in series it is A + B,

So far, so good.

Quote:
Originally Posted by M Code /forum/post/18241410


No you have it backwards..

when in parallel it is A + B/2..

Not quite!


If "A" and "B" are equal then it's:


A/2 or B/2 (both are the same answer)


If "A" and "B" are NOT equal then it's more complicated.

 

[MichaelJHuman]

If A and B are not the same impedance, I believe (from memory) the impedance of two resistors in parallel is -


( A + B) / (A*B)

 

[Speedskater]

Upside down!

It's:


( A * B ) / ( A + B )

 

[MichaelJHuman]



Quote:
Originally Posted by Speedskater /forum/post/18251898


Upside down!

It's:


( A * B ) / ( A + B )

Yep. Well, close enough for government work. Seems to me they landed a satellite in the wrong place due to a simple programming error.


At least it wasn't a fencepost error ( http://en.wikipedia.org/wiki/Off-by-...encepost_error )