Parallel/Series speakers connection .... - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 12 Old 11-28-07, 05:01 PM Thread Starter
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Parallel/Series speakers connection ....

I have some questions about speakers connected in parallel/series:

1. What happens if you connect four 8ohms speakers in parallel/series but the speakers have different frequency response??? ... you will get the 8ohms load, this supossedly won't represent a problem to the reciever (the speakers terminal shows that is safe to use 8-16ohm load). One speaker is rated 60Hz - 24KHz, two are rated 120Hz - 20KHz and the other 80Hz - 20KHz.

2. What about the efficiency??? ... Do this matters??? ...sensitivity varies from 85 - 89 to each speaker.

3. Do they have to sound the same??? ... I mean, at the same volume or one will sound louder than the other??? ... I'm not sure, but I think the sensitivity and freq response will affect the sound, Right???

4. Does it matter which way the speakers are connected??? ... Which speakers have to be in series and which one in parallel??? ... I'm using Polk M10, Infinity TSS 750 and Sony SSU551??? (discontinued, but hopefully will be replaced with some Polk ) ...here is a sketch of how I connected them (I didn't have time to do a fancy one) ...








If I understand correctly, the Polk and Sony are connected in parallel and the TSS is Series, Right??? ... Do you recommend a better connection
5. If the receiver is rated at 100/ch @8ohms and the speaker terminal shows 8-16ohms load ... Can this be used with a 4ohm load??? ... it is safe??? (receiver is Sony STR-DE897).

I'm asking this because I connected my front speakers this way ... I read before that is not the best option, but my front speakers were placed very high (near the ceiling) ... I placed a pair of towers on the floor (Sony) and they sounded good (I was using the A + B speaker, but I felt that I was missing something having one set on the floor and the other near the ceiling ... so I installed two more speaker between them to form an arch on the L and R side ... they sound better now, but I'm wondering if this is okay ... you see what happens when you're reading the forum and getting more ideas

Sorry for the long post
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post #2 of 12 Old 11-28-07, 05:07 PM
 
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Re: Parallel/Series speakers connection ....

When connecting in series/parallel connections two 8 ohm drivers in series will stay 8 ohms, but wire them parallel and it drops to 4 ohms. So I would suggest series wiring for your situation.
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post #3 of 12 Old 11-28-07, 06:45 PM Thread Starter
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Re: Parallel/Series speakers connection ....

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avaserfi wrote: View Post
When connecting in series/parallel connections two 8 ohm drivers in series will stay 8 ohms, but wire them parallel and it drops to 4 ohms. So I would suggest series wiring for your situation.
According to this http://www.termpro.com/articles/spkrz.html two 8 ohms in series will increase the load to 16 ohms and in parallel will drop to 4 ohms (you're right here)

In my case I'm using four speakers per set or side (four left and four right) ... that's why I combined series and parallel to keep the impedance at 8 ohms (if I understood and did it correctly) ... What do you think about the different frequency response and other questions???
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post #4 of 12 Old 11-28-07, 06:52 PM
 
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Re: Parallel/Series speakers connection ....

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According to this http://www.termpro.com/articles/spkrz.html two 8 ohms in series will increase the load to 16 ohms and in parallel will drop to 4 ohms (you're right here)

In my case I'm using four speakers per set or side (four left and four right) ... that's why I combined series and parallel to keep the impedance at 8 ohms (if I understood and did it correctly) ... What do you think about the different frequency response and other questions???
Oops you're right about the wiring I don't know what I was thinking .

As far as the different frequency responses you might want to put in some sort of passive crossover as the speakers not as capable on the low end may introduce some distortion. Sensitivities could be a problem, but the way it seems you have everything hooked up if you level match each wired section I think it would work out overall as the level matching would do the whole unit not each driver individually.

How does it sound?

Last edited by avaserfi; 11-28-07 at 07:15 PM.
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post #5 of 12 Old 11-28-07, 08:05 PM Thread Starter
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Re: Parallel/Series speakers connection ....

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avaserfi wrote: View Post
Oops you're right about the wiring I don't know what I was thinking . ... How does it sound?
There is a saying in spanish ... translated, will say something like: " Even the best chef can burn the food" ... in other words ... we can make mistakes.

The sound is great, before I was using a pair for each channel (A + B) but they were near the ceiling ... now with two pair each channel (floor, ceiling and two in the wall) I feel that the whole front is filled with the sound not like before ...
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post #6 of 12 Old 11-28-07, 08:35 PM
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Re: Parallel/Series speakers connection ....

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If I understand correctly, the Polk and Sony are connected in parallel and the TSS is Series, Right??? ... Do you recommend a better connection
The Polk and one TSS are in series. The Sony and the other TSS are in series. These two series units are in parallel with each other.

It's a poor idea I'm afraid. Putting two speakers in series, effectively divides the maximum voltage you can develop across each speaker in half. This doesn't unfortunately divide the power dissipated by each by half, but by about a quarter of what the single speaker dissipated because power is the square of the voltage divided by resistance.

Simply put, the volume will be a lot lower with two speakers in series and results in the necessity of a volume control increase to get the same volume. When you do this you are feeding more noise floor.

In addition, distortion will also be added to the resulting sound because both series speakers have a different impedance/frequency curve. This impedance imbalance will upset the voltage that would have dropped across each individual speaker if they were used alone. You will alter the response of the system.

The only advice I have is to use one speaker. If you must add more, put them in parrallel as long as you don't exceed the power amps capabilities.

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post #7 of 12 Old 11-28-07, 09:46 PM
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Re: Parallel/Series speakers connection ....

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brucek wrote: View Post
It's a poor idea I'm afraid. Putting two speakers in series, effectively divides the maximum voltage you can develop across each speaker in half. This doesn't unfortunately divide the power dissipated by each by half, but by about a quarter of what the single speaker dissipated because power is the square of the voltage divided by resistance.
EVen worse. Putting two different speakers in series subjects each to a series resistance that varies with frequency and that virtually assures that each will have its designed frequency response distrupted.

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post #8 of 12 Old 11-29-07, 04:11 PM Thread Starter
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Re: Parallel/Series speakers connection ....

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...The only advice I have is to use one speaker. If you must add more, put them in parrallel as long as you don't exceed the power amps capabilities.Brucek
My receiver doesn't say anything on the manual about using less than 8 ohms load but is printed on the back at the speakers terminal impedance 8 - 16 ohms.

I send an email to Sony, but they send me this link http://www.iq.sony.com/srvs/autoresp....asp?id=567882 that doesn't answer the question to my specific receiver

After looking at another models I found out on the speaker selection (A, B and A+B) that apparently when using the A+B the receiver does a parallel connection ... so, if I connect two 8 ohms speakers and choose A+B selection the load will be 4 ohms total ... or is per speaker??? ... this means, that I will be safe with a parallel connection using either speaker A or B, Right??? ... but what if I have a parallel connection on A and B and then combine them using the A+B (parallel according to manual) ... What will be the load??? ... 2 ohms??? .... How safe is to do it that way??? ... I don't know my amp capabilities below 8 ohms ... Can use this set up

What about using a speaker selector for my set up??? ... instead of doing all this parallel/series
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post #9 of 12 Old 11-29-07, 04:15 PM
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Re: Parallel/Series speakers connection ....

Your Sony tends to have areas that run pretty hot already. I would not recommend using speakers in parallel except at low levels and with plenty of ventilation. Running speakers in series is a bad idea, for several reasons, as noted above.




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post #10 of 12 Old 11-29-07, 04:24 PM Thread Starter
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Re: Parallel/Series speakers connection ....

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lcaillo wrote: View Post
Your Sony tends to have areas that run pretty hot already. I would not recommend using speakers in parallel except at low levels and with plenty of ventilation. Running speakers in series is a bad idea, for several reasons, as noted above.
Thank you for your advise.

What do you think about using the speaker selector???
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