70v System vs traditional...

J

Jason Hodges

Freshman
Jul 10, 2011
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Hopefully you guys can give a solid answer for this situation....
I am replacing a stereo system in a locker room. Its actually 2 rooms connected together. Each room is 30x30x15 cement walls and ceiling. Each room had 4 speakers with a volume control. This lead to a central receiver that controlled both rooms. This was a traditional 100v (?) system with 8 ohm speakers. The receiver died. Most of the speakers still work (6 out of 8).

So my de lima is to switch to a 70v system or use a traditional system. People have giving me insights on both systems and both sound good. I lingering questions is will a 70v system produce enough sound for a locker room setting? Or should I stay with a traditional system. If so can you point me in the right direction as far as components and brands that are quality?

Thanks so much for your time and help!!
 
Re: 70v System vs traditional...

Jason -

I think that you're confusing what a "traditional" system is vs. another form of constant voltage system. A 100v system works in just the same way as a 70v system, with constant voltage amps and transformers on each speaker, to put things in super simple terms. A "traditional" system forgoes those transformers and runs at "low impedance". I'd wager that this old system was running in such a low impedance manner and since you say "receiver" I'm assuming that was a home theater type deal. This means it was probably over driven as 4, 8ohm, speakers (assuming they were 8ohm each, which is pretty standard) produce a 2ohm load, while most home receivers are generally only made to handle 8ohms a channel, maybe 4 at best.

So how to replace it? Well as always "it depends". What volume and what fidelity are you trying to get out of this thing? If it's just background music going through some ceiling cans then sure, run it at 70 volt. You can get an affordable little constant voltage amp that will properly power everything and it'll make plenty of noise. However if you're going for loud, full range, lots of low end in your face RAWR LETS LIFT HEAVIER WEIGHTS type tunes, then I'd suggest running a low impedance system off a "real" commercial grade amplifier that's rated at 2ohms a channel (one for each room).

There still are so many variables though that without having been on the site and personally viewed and assessed the situation I'd be wrong to say what the proper way is to go about it, however I hope this helps you get started in the right direction.

-pete
 
Re: 70v System vs traditional...

Pete, Thanks for the response and clarification on 70v vs low impedance or traditional system! So I think I want to stay with a traditional system. Using 8 ohm speakers can I use this amp that someone recommended?

http://www.fullcompass.com/product/358517.html

Again I will have volume controls in each room that would be impedance matching. I would just like to use one amp for both rooms and will have one source (ipod) to direct music to both rooms.

Thanks again!!
 
Re: 70v System vs traditional...

Jason Hodges said:
Hopefully you guys can give a solid answer for this situation....
I am replacing a stereo system in a locker room. Its actually 2 rooms connected together. Each room is 30x30x15 cement walls and ceiling. Each room had 4 speakers with a volume control. This lead to a central receiver that controlled both rooms. This was a traditional 100v (?) system with 8 ohm speakers. The receiver died. Most of the speakers still work (6 out of 8).

So my de lima is to switch to a 70v system or use a traditional system. People have giving me insights on both systems and both sound good. I lingering questions is will a 70v system produce enough sound for a locker room setting? Or should I stay with a traditional system. If so can you point me in the right direction as far as components and brands that are quality?

Thanks so much for your time and help!!
Click to expand...

You don't mention where you are geographically. 100V is typical for overseas constant voltage systems, 70V in the US.

I am not aware of many receivers with CV outputs, and 8 ohm speakers don't work on 100V CV lines without a step down transformer. Were you using a step up transformer or driving the 8 ohm speakers directly from the receiver, or perhaps with a volume pad?

You can make adequate volume with 70-100v or low impedance systems.. there will be more wire losses with low impedance distribution, but perhaps more LF playback response.

Not clear what you currently have/had...

JR
 
Re: 70v System vs traditional...

Jason Hodges said:
Pete, Thanks for the response and clarification on 70v vs low impedance or traditional system! So I think I want to stay with a traditional system. Using 8 ohm speakers can I use this amp that someone recommended?

http://www.fullcompass.com/product/358517.html

Again I will have volume controls in each room that would be impedance matching. I would just like to use one amp for both rooms and will have one source (ipod) to direct music to both rooms.

Thanks again!!
Click to expand...

Yikes I don't know who recommended that but I really don't see it being good for what you need. Don't get me wrong or take me as a gear snob (there are actually some ART things that I find useful in the right application), but I don't see this being the right application for that particular product. Look more toward something like this:

http://www.fullcompass.com/product/391519.html

Crown, Crest, Ashly, etc... all make some really good options as well. Also consider an installation mixer/amp combo - there are a few good ones out there. Are any of these gonna be more expensive than that ART? Well sure, but you honestly get what you pay for.

I'm sure I'm not the only one on this part of the forum that has spent many a day tearing out systems that were put in because they were the cheapest option available.... that then failed or never preformed as needed, meaning in the end the customer payed way more than they would have had they payed a bit more up front the first time to do it right.

Try and be careful if you're feeling way over your head - sometimes it's better to pass on a job and make more money in the long run by getting future jobs that you can do the absolute best on and garner you a good reputation than getting a few bucks up front and becoming known as the guy who did a bad job and cost his customer more money in the end. Nothing beats a good reputation in this business! You've come to a good place to learn though so keep reading and asking questions as you move along.
 
Re: 70v System vs traditional...

Pete, Thanks for the words of advice and recommendation. Do I need to be looking an amp with 4 channel out vs 2? Since I will have 2 sets of speakers in each room for a total of 8?

John, I am here in the States, Michigan to be specific. And I didn't word my OP correctly. I should not of used '100v'. Its a traditional system.

Thanks again gentlemen for helping a newbie!

Jason
 
Re: 70v System vs traditional...

There are lots of white paper tutorials on the WWW explaining CV systems from all the major manufacturers.

These are similar but different products designed for the similar but different application.

Your 2 zones, 4 speakers per zone, driving relatively small rooms is borderline between being covered with a consumer low Z system, or dedicated install mixer amps and CV distribution.

I would be reluctant to ever install, non-install gear, since it won't always survive the wear and tear of install use (and 4 low Z speakers per side of an amp is pushing it for loading even pro amps).

If you have any interest in doing more install work, you should probably learn to do it right, and this could be an opportunity with a relatively simple job. If this is one off, maybe pass on it, or punt with another consumer front end, but hope the guy goes out of business before you have to fix it again.

JR
 
Re: 70v System vs traditional...

Seeing as your in Michigan I'd highly suggest calling up the guys over at ISP Technologies and asking about their High Definition Distributed system. We've got one of their concert rigs and it's been nothing but superb.

The HDD runs on CAT5/6 and might be a bit easier for you to understand as it solves the 70v/low impedance concerns you are having.

http://www.isptechnologies.com/

I'm with John on never installing non-install gear; it goes back to that whole reputation thing.
 
Re: 70v System vs traditional...

If there are four 8 Ohm speakers per locker room and each locker room is on a separate channel then using series-parallel wiring it would be quite easy to wire the system to have an 8 Ohm load per channel (two speakers in parallel in series with the other two speaker also in parallel or two speakers in series in parallel with the other two speakers also in series), you'd have to find out how the existing system is wired to determine if that is what was done. That approach may also explain why a speaker going bad in each locker room led to the demise of the receiver as a speaker going either open or short could significantly change the load on the amp output and cause the receiver to fail.

At least in my experience, a 70V system can typically provide more than sufficient level and quality for a locker room, but perhaps it would help to define the goals and expectations before discussing potential solutions. What type of venue is this, is it a fitness club or golf club or college/pro athletics facility? How do they use the system and what are the expectations and goals for it? What is the budget? Do you plan to replace all the speakers or to try to reuse what is there? Do both locker rooms always get the same audio or do they want to be able to address them as separate zones? A simple example of how this may matter is that a consumer receiver might make sense if they are using one with a integrated FM tuner for music or have multiple sources hooked to it, however it may not make as much sense if there is a paging mic or if it is tied into a building wide paging and/or background music distribution system. SO I think it is important to know what you are trying to do before addressing how to best accomplish it.
 
Re: 70v System vs traditional...

All good advice but if you do something cute like series-parallel speaker wiring, please document your system design and leave paperwork somewhere easily findable for future service calls.

Series-parallel is not quite as bad as the old series wired christmas lights, but a more complicated wiring scheme than traditional CV distribution. FWIW CV is all about the wiring. With higher voltage distribution you can use lighter gauge wire, and more easily make system alterations later when say adding another speaker on to the system (or removing one) is desired.

YMMV

JR

Note: Series-parallel speaker wiring is no more dangerous to the amp than any other wiring scheme..if anything less stressful than the simple parallel connection. A shorted VC is always stressful to the amp, but professional amps anticipate shorts and protect the amp.
 
Re: 70v System vs traditional...

Just to clarify in light of JRs comments, I was not recommending a series-parallel approach as a solution, and if you do use that approach I strongly agree about documenting it, but rather addressing the earlier comment that four speakers would equate to a 2 Ohm load as that all depends on the wiring scheme used. The other potential element in that is the volume control as that could come in a number of different 'flavors', especially with some consumer oriented products.

Another benefit of 70V systems in some applications is that it can be fairly simple to adjust the relative level of individual speakers without requiring accessible volume controls at the individual speakers via the proper selection of of transformers and the associated tap values.
 
Re: 70v System vs traditional...

Brad Weber said:
If there are four 8 Ohm speakers per locker room and each locker room is on a separate channel then using series-parallel wiring it would be quite easy to wire the system to have an 8 Ohm load per channel (two speakers in parallel in series with the other two speaker also in parallel or two speakers in series in parallel with the other two speakers also in series), you'd have to find out how the existing system is wired to determine if that is what was done. That approach may also explain why a speaker going bad in each locker room led to the demise of the receiver as a speaker going either open or short could significantly change the load on the amp output and cause the receiver to fail.

At least in my experience, a 70V system can typically provide more than sufficient level and quality for a locker room, but perhaps it would help to define the goals and expectations before discussing potential solutions. What type of venue is this, is it a fitness club or golf club or college/pro athletics facility? How do they use the system and what are the expectations and goals for it? What is the budget? Do you plan to replace all the speakers or to try to reuse what is there? Do both locker rooms always get the same audio or do they want to be able to address them as separate zones? A simple example of how this may matter is that a consumer receiver might make sense if they are using one with a integrated FM tuner for music or have multiple sources hooked to it, however it may not make as much sense if there is a paging mic or if it is tied into a building wide paging and/or background music distribution system. SO I think it is important to know what you are trying to do before addressing how to best accomplish it.
Click to expand...


Thanks Brad and the rest for your comments and help. It looks like the system was setup in parallel. So that wold take the two 8ohm speakers on the channel down to a 4 oms per channel. I think!

Expectations are for a single source to both rooms. One ipod control the music. But each room would need a volume control. The sound should be good, with full range and some bass. These kids want to crank it up at times and rock it out at times. As far as cost, hopefully around $2,000. But we want something that will last.

Another questions is if I do go with a 8ohm system with 4 speakers in each room can I use 2 2-channel amps and somehow connect the same source to both amps. This is due to the cost of a 4 channel amp from people like Crown. Or can I use a 2 channel amp that can handle 4 sets of speakers. I am sure impedance matching volume controls is a must?

Thanks again folks!!
Jason
 
Re: 70v System vs traditional...

Jason Hodges said:
Thanks Brad and the rest for your comments and help. It looks like the system was setup in parallel. So that wold take the two 8ohm speakers on the channel down to a 4 oms per channel. I think!

Expectations are for a single source to both rooms. One ipod control the music. But each room would need a volume control. The sound should be good, with full range and some bass. These kids want to crank it up at times and rock it out at times. As far as cost, hopefully around $2,000. But we want something that will last.

Another questions is if I do go with a 8ohm system with 4 speakers in each room can I use 2 2-channel amps and somehow connect the same source to both amps. This is due to the cost of a 4 channel amp from people like Crown. Or can I use a 2 channel amp that can handle 4 sets of speakers. I am sure impedance matching volume controls is a must?

Thanks again folks!!
Jason
Click to expand...
Is the budget just for the gear or for gear, installation, warranty etc.?

One of the problems you are going to run into is that pretty the highest wattage you will beable to get on a speaker level inline volume control is 100 watts. That could be a limiting factor if you want to get loud.

Of course ther are all sorts of VCA type signal level volume controls, but that could limit your flexability of control, or you will need more amplifiers etc-therefore driving up the costs.

You can drive multiple amps from the same source with no problem.

Of course the easiest way to have a volume control is simply on the front of the amp-but that may or may not be convienent for adjustment.

With flexability comes costs. Simple as that. A simple system that is limited is less expensive. It is up to you and the customer to determine what is best for your situation and budget.
 


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