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Author Topic: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?  (Read 1719 times)

Ryan McRobie

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Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« on: October 04, 2013, 05:33:15 pm »

Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer? I am working on an outdoor landscape speaker project with 10 speakers connected per channel to a Crown CDI-1000. The owner purchased 4 Ohm rock speakers and 8 Ohm outdoor 70v transformers. The transformer is a TIC SP70VTA. Will this work correctly?
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John Roberts {JR}

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #1 on: October 04, 2013, 06:48:57 pm »

Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer? I am working on an outdoor landscape speaker project with 10 speakers connected per channel to a Crown CDI-1000. The owner purchased 4 Ohm rock speakers and 8 Ohm outdoor 70v transformers. The transformer is a TIC SP70VTA. Will this work correctly?
I ASSume you mean a 4 ohm speaker on an 8 ohm tap of a 70V transformer.

You could wire two 4 ohm speakers in series per 8 ohm transformer.  This may involve more wiring out in the yard than is desirable.

Then connect to 2x the desired power tap (per speaker) since speakers will split the power between them.

or not..

JR
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Brad Weber

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #2 on: October 05, 2013, 09:52:07 am »

The owner purchased 4 Ohm rock speakers and 8 Ohm outdoor 70v transformers.
Maybe whoever put that combination of speakers and transformers together should come up with either the correct parts or a solution.
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Ivan Beaver

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #3 on: October 05, 2013, 11:05:46 am »

Maybe whoever put that combination of speakers and transformers together should come up with either the correct parts or a solution.
It is amazing to me how many people will ask others help on a problem-yet never go to the person who "designed" it and make them make it right.

I see this all the time in the install world.  The people who designed a faulty system get paid in full-yet are not required to make it work/cover properly.

So the customer has to spend more money fixing the poor design.

And the offending "designer" goes on to screw another customer----------------------------

I see system that could not have worked since day one-but yet somebody said "That is fine-here is a check" for a system that simply does not work properly.

Amazing how many incompetent "designers" there are in audio.  All you have to do is be able to hook it up and make sound-and somehow you are an "expert".  WOW.

I better stop now before I say something that might offend somebody----------------
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

John Roberts {JR}

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #4 on: October 05, 2013, 11:44:26 am »

You are ASSuming they bought the exact parts that were spec'd.

It seem unlikely to spec 8 ohm transformers "and" 4 ohm speakers.

Even I wouldn't do that. :-(

JR
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Ryan McRobie

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #5 on: October 05, 2013, 08:17:37 pm »

You are ASSuming they bought the exact parts that were spec'd.

It seem unlikely to spec 8 ohm transformers "and" 4 ohm speakers.

Even I wouldn't do that. :-(

JR

Actually I spec'd a sonace system with transformers included in the speakers. The client didn't like the price of the speakers and purchased the other ones on their own. I have been asked to install them. I told them before posting on here that it will not work correctly. What I would like to know is what would happen if they were installed this way. Obviously I have never tried it and ASSume that it would overload the power amp. Thank you for your time.
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John Roberts {JR}

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #6 on: October 05, 2013, 08:36:20 pm »

Actually I spec'd a sonace system with transformers included in the speakers. The client didn't like the price of the speakers and purchased the other ones on their own. I have been asked to install them. I told them before posting on here that it will not work correctly. What I would like to know is what would happen if they were installed this way. Obviously I have never tried it and ASSume that it would overload the power amp. Thank you for your time.

Tell the client he is a dumb ass.

The 8 ohm transformer is making 1.41x the nominal voltage correct for 4 ohm loads.

Since the transformer appears to have different power taps, you can tap it at 1/2 the 8 ohm power and will put that into the 4 ohm speaker (5w 8 ohm tap will make 10W at 4 ohm.)

The transformer is obviously not optimal but if tapped at well below the max power the transformer is capable of, it could work.

If you put pairs of 4 ohm speaker in series, like i already suggested the transformers will not know any difference.

So as long as you keep in mind that you are pulling two times the watts that the tap says you are with 4 ohm speakers, you should not overload the amp.  I wouldn't try to push a lot of low bass through the system, but i wouldn't try that with 8 ohm speakers either.

JR
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Jim Thorn

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #7 on: October 06, 2013, 01:17:52 am »

John Roberts has the answer.  Each transformer tap will simply supply twice the marked power to a four ohm speaker,.  Since the transformer is rated to handle 20 watts, just use the 10 watt tap, knowing that it will deliver 20 watts to the four ohm speaker.  With 10 speakers per channel, you will only be asking for 200 watts per channel from your 500 watt per channel amp.  If you never looked at the labeling of the taps , but checked your finished system with an impedance meter, you'd see nothing to be alarmed about.  You'll be fine.

Jim Thorn


[ :)quote author=Ryan McRobie link=topic=146386.msg1346888#msg1346888 date=1380922395]
Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer? I am working on an outdoor landscape spea :)ker project with 10 speakers connected per channel to a Crown CDI-1000. The owner purchased 4 Ohm rock speakers and 8 Ohm outdoor 70v transformers. The transformer is a TIC SP70VTA. Will this work correctly?
[/quote]
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Brad Weber

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #8 on: October 06, 2013, 08:13:50 am »

JR covered well how it would work and Ivan covered the frustration of being asked to invest your time, effort and expertise to try to compensate for someone else trying to save a few cents.  Maybe your Owner should send JR a check for the difference between what they bought and what they should have bought, it seems only fair.  ;)
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duane massey

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Re: Is it OK to connect 4 Ohm speakers to a 8 Ohm 70v transformer?
« Reply #9 on: October 22, 2013, 06:15:15 pm »

So, the final answer to the original question is "Yes, it will work if you use the lower tap".
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Duane Massey
Technician, musician, stubborn old guy
Houston, Texas
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