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Old 4th March 2006, 09:35 AM   #1
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Default 100V systems

A question, could a transformer (badly) influence the frequency response and the decay?
And makes it a difference in frequency response and decay when you run a 100v speaker trough a low impedance amp? (it is possible to run some of these speakers on a regular amp)
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Old 4th March 2006, 11:03 AM   #2
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Yes, the transformer can affect the FR
No, it is not possible to run a 100V line system from a normal amp.
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Old 4th March 2006, 11:30 AM   #3
AuroraB is offline AuroraB  Norway
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The FR is of course somewhat affected, but the extent is mainly determined by the quality of the transformers in use .... all tube amps have output transformers, don't they...??

Most of the modern amps made for 100V systems are quite plain transistor amps with a transformer to the output. There is as such no reason to say you cannot use a 100V transformer with an ordinary amp, but any stability problems with this amp might be enhanced....it's only a matter of getting the loads right...

100V systems are normally not used for their fantatstic sound quality, but for distribution systems over large areas/ distances.
Would be perfect for "background music" in your house
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Old 4th March 2006, 12:17 PM   #4
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I know that it's not really suitable to run a 100v speaker with a regular amp. It's just that I measured a 100V speaker with a regular amp. The freq response and the decaydiagram are terrible of this unit (fullrange unit).
So how badly does a transformer distort the freq. response and the decay time
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Old 4th March 2006, 12:30 PM   #5
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Quote:

No, it is not possible to run a 100V line system from a normal amp

Actually it is possible to drive a 70v or 100 v line from a large amplifier in bridge mono mode.

The output voltage of the amplifier is going to have to large enough.

I have done this 100's of times on commercial systems without a problem.

There would be NO advantage to using a 100v system at all in home audio. The quality will suffer because of the loss in response from both the step up transformer if using one on an amp and the step down transformers at the speakers.

One could use a 25v or 70v system thru a house or grounds area because you can drive extremely long runs with small cable size.
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Old 4th March 2006, 12:51 PM   #6
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I know it's no use to place a 100v system in my home. And I know that it shouldn't be used for hifi.
But, I didn't even mention that in my post that I would actually going to use the speaker.

It's just that I wanted to know the freq response and decay diagram of the speaker so I measured it.
Since the results are bad(really bad), I thought the transformer may cause some trouble.

The speaker I measured is a small Bose (Pro) speaker, with the infamous 4,5" fullrange unit. I can post the results if you want, but they are horrible. A massive resonance peak at approx. 2khz, and a freq. response thats ugly as .....

Since I'm not very pro bose, I wanted to measure it and see what would come out.
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Old 4th March 2006, 01:05 PM   #7
AuroraB is offline AuroraB  Norway
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Just for the record.....of course you cannot run a 100V system DIRECTLY from a normal amp - you will need an e.g 8ohm/ 100V step-up output transformer to do this, as is done in most commercial 100V amps. From thereon it's just like any other installation sound system in any warehouse, just to mention one example.

I never implied it to be HiFi, but it could be useful if you want music "eveywhere" in your house, as the distribution is very simple....standard TP cable is quite sufficient for "muzak" level and quality.
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Old 4th March 2006, 01:29 PM   #8
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Quote:

Just for the record.....of course you cannot run a 100V system DIRECTLY from a normal amp - you will need an e.g 8ohm/ 100V step-up output transformer to do this, as is done in most commercial 100V amps.

Did you not read my post?

I thought I explained in enough detail how it can be done. Naturally the amplifier has to be large enough
to obtain the output voltage. This CAN and is done tryically in the commercial world everyday and without problems. If the amplifier is large enough and is run in MONO BRIDGE mode this CAN be done.

Examples:

An Altec 9440 power amplifier was typically used to drive a 70 volt line even though its output was 4 or 8 ohm. When switched to MONO BRIDGE mode the amplifier was capable of putting out 800 watts(typically I benched these amplifiers at 885 watts). If you do the math this exceeds the needed voltage to drive a 70 volt line.

An Altec 9446 would mono bridge at over 1300 watts typically which is more than capable to drive a 100volt line.

In other words... If the amplifier in question is capable to putting out the necessary drive voltage a step up transformer is NOT needed.

It is common practice to use some of the newer QSC amplifiers to direct drive a 70 or 100 volt line.

Typically, one would prefer to use a step up transformer for commercial 70 or 100 volt systems. Sometimes however one may not have a transformer on hand.
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Old 4th March 2006, 01:48 PM   #9
AuroraB is offline AuroraB  Norway
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Sorry, but the original post was not exactly crystal clear as to what he intended to do....so we are talking past each other..
of course- any amp capable of delivering 100V at full blow can be used, but in the world of hifi and diy, this is not quite a normal amplifier...nor is the Altec's you refer to.......
To me- and most of us, I guess- a normal amp would be something up to ca. 200W designed for 8 ohms output.... this would be roughly 50V average output voltage, - not quite enough to fully drive a 100V loudspeaker.......but it can be done- with the step-up trafo.
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Old 4th March 2006, 01:58 PM   #10
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Sorry,

In the commercial world I live in everyday I am used to playing with amps putting out 1200 watts per channel and not thinking much of it. You are correct....in the home usually an amp around 200 watts or less will be used.

In the case of a small amp a transformer or autoformer is in order.
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