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Author Topic: 70v system / "dance studio"  (Read 7707 times)

Charlie Zureki

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Re: 70v system / "dance studio"
« Reply #10 on: June 12, 2012, 05:06:58 pm »

I'm aware of the pitfalls of 70v systems, where I'm getting hung up is how (from other postings) there is virtually no low frequency information below xx Hz depending on what transformer is used. That being said, if you use a...

to feed the subs, AND there is virtually no LF information present at that point, what good are the subs? It's like connecting a fire hose to an empty hydrant.

   Hello,

   I don't know where you've gotten the opinion that there is NO LF information present when using these transformers...  there is definitely less LF, in typical gear, but, it is not non existant.   Secondly, Subs designed to work with 70v or 100v systems have larger transformers, they will reproduce much of the LF. 

   Demo a few different Subs.

   If you really need to shake this dance studio, then,  you may need to step up to the low impedance gear. (and you may need to double, triple or more your budget)  But, since you're already into the 100v gear, try adding some demo subs. It may be exactly what you're looking for.

  Try it... then, come back and tell us what you think.

  Hammer 

   ps.  don't listen to anonymous people on other sites... generally, they're anonymous for a reason.
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Ryan C. Davis

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Re: 70v system / "dance studio"
« Reply #11 on: June 12, 2012, 05:24:28 pm »

I'm not trying to perpetuate that there's nothing there, I'm asking a question based off of a post in THIS thread by Mr John Roberts and quoted below. I'm just trying to figure out how much LF info there is even with a good transformer. I thought it was a valid question but I think it's just getting confusing now so I'll stop. I apologize for the tread-jack. 

Constant voltage systems are used for background music all the time. You should be able to find specs on the speaker... they rate response to 70Hz, so not going to rattle the room with massive bass notes.

In general constant voltage systems (100V in Japan) are not very accommodating of high level low frequency content because of all the transformers in the path stepping up the signal to 100V and back down to low voltage for the speakers. Extending the response to lower frequency requires more iron and copper (in other words more Yen). To pass full audio power at 60Hz the output transformer needs to be roughly the same size as the power supply transformer. To pass that same power at 20 Hz the audio transformer needs to be 3x larger than the power transformer.. 

You can probably add a few low voltage subs to the system, HPF the constant voltage feed to make their life easier and get all the bass you want. It depends on how loud and low you need to go.

JR
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Ryan Davis

Greg Ruddell

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Re: 70v system / "dance studio"
« Reply #12 on: June 12, 2012, 07:33:29 pm »

I'm aware of the pitfalls of 70v systems, where I'm getting hung up is how (from other postings) there is virtually no low frequency information below xx Hz depending on what transformer is used. That being said, if you use a...

to feed the subs, AND there is virtually no LF information present at that point, what good are the subs? It's like connecting a fire hose to an empty hydrant.
No, not at all. Whatever signal is present on the line from the amplifier is what will determine how much LF exists at the 70 volt to line level transformer which is what will be feeding the signal to the subs. The transformer might begin to roll off the LF around 40, but it will be a gradual slope. I have used these transformers in retail environmnets along with powered subs and there was more than enough LF http://www.mysoundacoustics.com/SND-T70-LINE.htm

There are quite a few decent 70 volt amplifiers available now that produce a wide bandwidth http://www.crownaudio.com/amp_htm/cts.htm#2chspec. . Also, depending on the impedance of the system, you can use a high power amp capable of delivering the required rail voltage without the need for a step up transformer.

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Ryan C. Davis

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Re: 70v system / "dance studio"
« Reply #13 on: June 12, 2012, 09:36:27 pm »

thanks for the tip. We've done a fair amount with 70v systems but never really requiring a sub so I'd never crossed that path. Appreciate the tip!
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Ryan Davis

ProSoundWeb Community

Re: 70v system / "dance studio"
« Reply #13 on: June 12, 2012, 09:36:27 pm »


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