I need professional advice please...


New member
Username: Cassidy

Post Number: 1
Registered: Apr-04
I have a Crest Audio Vs 1500 amplifier.
It is apparently quite powerful. My plan is to drive 8 pairs of in-celing speakers with it, for a whole house audio system. The speakers will get light duty use most of the time, but occationally I plan to crank the volume for parties.
My question is what do I need to do to make it work. :P
I realize this is a little broad...
Maybe I can specify more...

I will have various sources going to a harmon/kardon preamp to the Vs1500 to either a 8 way speaker distribution panel or a speakercraft 8 zone speaker selector then to individual volume controls then to the speakers.

Do I need the 8zone speaker selector or can I just use the distribution panel? The selector says it has impedance matching circutry.
But the specs for the amp say it can put out more power if the impedance is lower. What would happen if i didn't have impedance matching circutry. I've also seen impedance matching volume controls; are those of use?
And finally, what speakers are the best to use for this set-up?

If anyone could offer some advice it would be greatly appreciated...


Jan Vigne
Unregistered guest
If you don't have any impedance matching circuitry and you are going to drive 8 pairs of speakers simultaneously, unless you are a wizard with parallel/series wiring, you will be buying a new amplifier on a very regular basis. There are no "best" speakers for this. Pick what you like the most within your budget. Find the impedance of the speaker (try to stay at 8 Ohms or higher) as well as the impedance swing across its frequency response, you need to know the low and high value. The speaker manufacturer should be able to supply this. Determine how many sources you need to play in different areas and that is the number of zones you will need to distribute with the pre amp. The CD player to seven sets of speakers and the DVD/TV in one romm equals two zones. Not hard to accomplish. More than two zones can get expensive. You will need amplification for each zone, in the example above you need amplification for two zones and eight pairs of speakers. I will assume you have the DVD/TV system worked out. To deal with the other seven pairs of speakers you will need fourteen channels of amplification (assumimg stereo in each area). You can purchase a single amplifier that has been divided into an adequate (14) number of channels (expensive)or buy two amplifiers that will provide the correct number (not as expensive but still not cheap) or buy seven separate stereo amps that will do the job (probably pretty expensive if not just a tall stack of gear). And don't get me started on the benefits of monoblocks! Let's say you choose to buy two amps with eight cahnnels each. That should not be too difficult to find in today's market. The output from each channel can be directed to a single speaker through a volume control and preferably a switch to allow you to turn off a speaker when you so desire. (Do not just turn down the individual area's volume control to turn off a speaker, the amplifier will hunt down you and everyone you love and do unspeakable things in the night.) That's the correct way to solve your problem but fairly expensive. The other option is to buy one amp that has adequate power to drive all the speakers at one time to sufficient volume levels (this could also get pretty pricey as this might require a really, really BIG amp). This will definitely limit you to the same source playing through all those speakers other than the DVD/TV room. You have to assume that every time you add a pair of speakers you will be distributing half of the remaining power to that pair of speakers. Let's say you buy a 100 watt stereo amp that can drive a low impedance, very reactive load. ($$$$$$) Not counting the loss from the resistance of the cables, switches and volume controls you will have 50 watts to drive two pair of speakers, 25 watts for three pair, 12.5 watts for four, 6.25 watts for five, 3+ watts for six pair and 1.5 or so watts max to simultaneously drive seven pair of speakers before the amp will clip. Those speakers better be pretty efficient!!! Particularly if you intend to crank it up for parties. I guess you could tell your architect you want to install Klipschorns in the ceiling of each room. Once you show him the picture and tell him they weigh 125 lbs. each you will see what kind of cheese your architect is really made of. Now you have to deal with the fact that the impedance goes something like this (we'll assume the best possible case and know you will almost always end up with the worst): 1 pair = 8 Ohms, 2 = 4, 3 = 2, 4 = 1, 5 = .5, 6 = .25 and finally seven pairs of speakers hooked up in parallel will result in an impedance of .125 Ohms. Imagine what we get if each speaker starts of at 4 Ohms. And that is before we look at the impedance swing of the speakers or figure in the resistance of the wire, switches and volume controls. I can smell the burning circuit boards and output transistors as I write this. Plus, I'll mention the whining noise of the cooling fan(s) obscuring the music in at least three of the rooms. In other words, I don't know of an amp that will be happy with that load so you will need something more than impedance matching circuitry. The speaker switches that say they will compensate for impedance normally do not offer much except a power sponge and will not suffice for this application. The best choice is to utilize either 25 or 70 volt transformers which most consumer amps will not like (we're back to burning and melting amps again) or find a switching/distibution system with autoformers. This, like the amplifier to drive all these speakers, will not, if it is well engineered and manufactured, be inexpensive. Bottom line is - unless you have A LOT of cash to drop on this arrangement you might want to reconsider your choices and then head to a competent audio dealer for some one on one advice.

New member
Username: Cassidy

Post Number: 2
Registered: Apr-04
Hey, Jan, thanks for your post. I was able to understand your advice for the most part..:-)
Suppose this, though.
The amp I have is rated for 1000W (one thousand) per channel, into 2 ohms
It is rated 400W per into 8 ohms.
I'm not sure what difference this makes in the math, but this is the reason that I was planning on driving every thing with it.
I recieved the amp when I purchased the building.
Do you think this large amp makes any difference to the advise you are presenting?

Thanks for your time again

Jan Vigne
Unregistered guest
Ok, I pulled up the Crest Audio web site and they are a commercial sound reinforcement company. There is no mention of the series of amp you now own but it would appear to be an amplifier meant to distribute sound to a large space through numerous loudspeakers. All this could be to your benefit or not depending on what you find when you contact the company. Thier contact numbers are on the web site and you will, at this point, get better answers from them than anyone out here. You could easily have an amplifier that is meant to drive a 25 or 70 volt distribution system. If that is the case you really should get a professional familiar with that type of layout to do the installation or you will end up with a mess. None the less if you are just hooking speakers up in parallel (the most common method for this purpose) you can see from the information I gave you before you can only hook up three pair of 8 Ohm speakers in parallel before you hit your 2 Ohm limit. I also don't know where you will find switches and volume controls that will take that much wattage without simply melting down when you crank the system up. All that makes me feel you are trying to use the wrong amp for your stated purpose. You may be in posession of a distribution type amp that was meant for PA (Public Address) and may not be suitable for music under a more critical setting. I don't know since your amp is not listed as a current product and this company makes amplifiers for everything from small clubs to football stadiums. Contact Crest Audio and get good information and then go from there.
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