Hey Guys,

Designing a 70v distributed audio system for a commercial installation. I'm well aware 70V has limited sound quality issues but want to provide the best possible under this restriction.
There are 5 single point stereo speakers and 3 pairs of stereo in ceiling speakers involved.
I Want to get as good a quality sound as possible, so quality low impedance speakers will be used throughout.
Since a great deal of the response is lost in the transformers, can anyone suggest a make and model you've had luck with?
Also, Since on wall volume controls will be available to the client, will those transformers impede the sound quality as well? ( I suspect yes)
I know the natural response will be why don't you use a low impedance system in the first place?
The reason is this is a growing office and plans are to expand widely in the near future within the same building.

Thanks,
GP

What do low impedance speakers have anything to do with sound quality?

How are you gonna get stereo in a 70v system? Run two amps to each speaker?

My favorite supplier can assist with this.

George Pope,

What is the purpose of the audio? Background music, paging, state of the art music in each little space? Does every area play the same music? Do users have any control over music choice? 5-10-100-++ speakers? What is the ratio between stereo and mono areas?

This is absolutely untrue. We are most familiar with POS audio systems costing the very least -- think 100 8" full-ranges in a supermarket ceiling -- and therefore conclude that 70 volt fidelity is crap. A bunch of 8 ohm speakers selling for twenty bucks apiece would sound just as bad. You have to get serious about 70 volt to get good sound, that's all. Consider Tannoy, JBL, and Soundtube.


Wait -- you've not only already bought 8 ohm speakers, but bought single point stereo speakers? Or do it depend on what the meaning of "are" are?


False premise, much extra money must be spent to get the sound you want.


cheap

Look into the three brands I suggested.

Use 70 volt transformers.   EDIT:  Use 70 volt VOLUME CONTROLS


No, the natural response is that you should find a pro who understands 70 volt speaker systems and have them consult to get your system designed. Fred can do a lot of this for free, but I don't know if he has all those brands.


A 70 volt system is the IDEAL system for anything that is growing, since you can plan in advance to supply more power than is needed now, then simply daisy-chain more speakers in the future.

Off the 8 ohm idea. It's just wrong.

70 volt systems can ROCK when covering a large area.
I've impressed a ton of "audiophiles" with a properly designed system.

I suggest that you call Fred for more info.....he knows as much as I do and can point you in the right direction.

Don't be swayed by the perceived limitations.......fidelity IS obtainable!

I edited my post. I was in a hurry and wrote "transformers" when I meant "volume controls."

Really, for most practical purposes the only difference between 70V systems and home audio is the math. The 70V math used for commercial applications is more straight forward. In many respects one could use "25V math" for home audio -- but you'll still max out at two pairs of 8-Ohm speakers for most amplifiers. Of course, you could resort to autotransformer volume controls for the home system too. (Ever wonder why these home controls look exactly like the 70V controls, but with home friendly trim plates?)

And, the traditional 70V volume controls are ugly -- and not usually available in stereo. (but, dig around, friendlier controls are out there)

70V systems can and should sound pretty darn good. I have a couple of 70V systems made up of Terra and JBL speakers, DBX pre and Crown amps that has pretty damn good fidelity in a challenging large gym environments. Fred was very helpful on the engineering side of them.

My system, I wrangled together, on ebay, with used QSC 70 volt amps, used Raine controls/mixers/crossovers, 2 inceiling subs, 28 used QSC 70 volt 5 1/4" 2 way enclosure cans dispersed evenly throughout our dining room and bar in our restaurant F'N ROCKS!!!!

Just so happened a QSC sales rep happened to visit our place last week to eat and drink... He was asking our bartender what company did our system and we had a long chat about the fact I used to be in the biz and taught myself 70 volt design. He complemented me on the sound quality of our system.

George Pope? Are you listening?

Yes, they're ugly, because the usual customer is commercial. However, I've been working with a guy who gets Decora controls, so there's no ugliness problem.

70 volt and stereo are different worlds. You don't find stereo 70 volt controls because 70 volt stereo is a silly idea.

"Stereo" means "solid" and the idea is that you have TWO speakers that, because of their fidelity, positioning, and the acoustics of the room, give you a hard image of where the different players are from the ONE SPOT in the room that's perfect. The sweet spot.

On the other hand, if you need to fill a space with music and hear all the music everywhere, you mix the two channels of stereo to mono before they go to the amp. All speakers then have all the audio.

And with a 70 volt system, the quantity of speakers is solely dependent on the power of the amp and the powers at which you tap the transformers. If you try multiple 8 ohm speakers, you have to series and parallel speakers to get them to present an 8 ohm load to the amp; this means your speakers are always multiples of 4. With 70 volts, if you have 13 speakers you can easily add two more for a total of 15 with zero problems... if you have planned the transformer tap levels correctly.

Atlas offers decora style 70 volt volume controls, rated at 10, 35, and 100 watts.
Available at my favorite supplier.

Depending on how the area is split, you may not need a typical speaker-level volume control, but a different amplifier and design.
Several amplifiers from Crestron, TOA, QSC and others have low voltage remote input on them that use a simple potentiometer to control the output. This would cut that loss at the VC.

And they are awesome.

I'm going to jump on the I suggest you call Fred band wagon here. I'm not giving you crap but there are a few key things to learn here and he will guide you right. Also, I suggest you go listen to a quality 70v system. We do large scale Model home complexes in the 180+ speaker range and many clients that walk those complexes request it for their yards.

For me the Amp would be QSC. The total possible growth would be accounted for and overhead room in the amp would be no less than 80% (shoot for 100%)

Speakers would be OWI or Atlas makes a really nice sounding in-ceiling with back box depending on what you are doing.

Volume Controls by Atlas.

Seriously, Call Fred. I do 70v regularly and I call him from time to time.
Last year I stopped him at Cedia to ask about a unique situation and I was quite surprised how deep his knowledge goes. He called me after the show, we built the system and it has become very popular.