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Go Back   WakeWorld > >> Boats, Accessories & Tow Vehicles Archive > Archive through April 04, 2003

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Old    dmpappy            03-07-2003, 1:48 PM Reply   
Quick question for all you audio gurus or electrical engineers out there.

Will 4 ohm speakers put out better sound quality when run with a 4 ohm load to the amp? Are they louder?

Assuming your amp is stable at 2 ohms, wouldn't it be more economical to run these types of speakers "daisy chained" to make a 2 ohm load? Doesn't the 2 ohm load in effect double the wattage of the amp?

I'm thinking about upgrading the tower speakers to the Defcon III's. These can be wired either daisy chained and run with a two channel amp or hooked up "normal" if you have a 4 channel amp.

What would be the advantages of going 2 channel vs. 4 channel amp for this application?

Thanks.

Old    mikep            03-07-2003, 3:41 PM Reply   
Your Question: Will 4 ohm speakers put out better sound quality when run with a 4 ohm load to the amp? Are they louder?
>> Depends on the amp. Some amps are 2 ohm, 1 ohm, or .5 ohm stable. However, in most instances, the lower you drop the ohm load, the more distortion. A high quality amp will still have low distortion, even when the ohm load is dropped down.

Your Question: Assuming your amp is stable at 2 ohms, wouldn't it be more economical to run these types of speakers "daisy chained" to make a 2 ohm load? Doesn't the 2 ohm load in effect double the wattage of the amp?
>>Again it depends on the amp. With Precision Power, for example, the watts are doubled, but with other amps it might be less than double.

Your Question: What would be the advantages of going 2 channel vs. 4 channel amp for this application?
>>The advantage of going with a four channel for four tower speakers could be:
- less distortion
- The ability to adjust the levels per pair of speakers
- The ability to cross over speakers at different frequencies. For example, if two of your tower speakers were 5-1/4" and two were 6-1/2", you might want to cross over the 5's higher than the 6's.

I hope this helps.


Old    Psyclone (cyclonecj)      Join Date: Jul 2001       03-07-2003, 5:44 PM Reply   
There is one other thing to consider, the lower (larger) load you run at the speakers, the more important the speaker wire becomes. If you are dropping (not realistic, just an example) .2 ohm in the cable you will drop (a teeny bit less than) 10% of output power in the wire with a 2 ohm load compared to 5% with a 4 ohm load. That is why home stereos use 8ohm impedance, they are designed to drive long wire runs. PA audio output impedance is typically 16 ohms, even longer wire runs. Just be aware that if you run lower impedance, be sure to use decent quality speaker wire and connectors. You would probably be better off with one big fat wire on each side daisy chained to a second speaker for a 2 ohm load than with two skinny wires on each side feeding one speaker each @ 4ohm, if your amp can handle the load. Speaker wire is non-reactive when used to drive a current load like a speaker. There is no such thing as "skin effect" with speaker wire. It is BS that manufacturers propagate to sell you $10 worth of wire for $50. Buy some quality, flexible fine stranded speaker cable, name brand if it makes you feel better but don't buy the super high end stuff, it is a waste of money. It will rot in a boat after a couple of years and need replacement anyway. I use the fat stuff from Home Depot, .39/ft. Works for me but I am not a true "audiofool" and have too much water in my ears to hear the difference anyway!
Old    xtigeman            03-08-2003, 5:30 PM Reply   
A few follow ups on the above.

Will 4 ohm speakers put out better sound quality when run with a 4 ohm load to the amp? Are they louder?

Yes, unless regulated power supplies and etc. McIntosh for instance produces the same wattage and the same .0015 THD whether the load is 2 ohm, 4 ohm, or 8 ohm.

I can speak from experience with regard to PPI, Zapco, Arc Audio, Pheonix Gold and lesser priced stuff. The amps do not sound the same in 2 ohm. Spec wise, the THD differences are nominal and not within the purview of human hearing. The sound, however, is definitely brighter in 2 ohm. The amps curves apparently dip more in the 40 to 1k range resulting ina brighter more hollow sound.

Still the same power going to each speaker, but the load on the amp affects the sound spectrum. It is fine for subs as you are crossovering 120 or so and high and you will not hear a funky sound curve cuased by dips in lows and increases in highs.

*********************************************** **

Assuming your amp is stable at 2 ohms, wouldn't it be more economical to run these types of speakers "daisy chained" to make a 2 ohm load? Doesn't the 2 ohm load in effect double the wattage of the amp?

In 2 ohm with two speakers, each speaker see the full wattage. If you have 100 watts X 2 @ 4 ohm for two speakers and 200 watts X 2 @ 2 ohm for 4 speakers, each of the four speakers see 100 watts. You are not doubling the wattage to an single speaker. The amp is doubling output to play the two speakers at the same level of 100 watts.

2 ohm in full range is not really a good idea. This places a lot of straighn on the amp. 2 ohm for subs if cool.

It would seem more economical, but you sound will suffer in full range applications. You will also have issues of heating to deal with and will be more prone to clipping your speakers.

I try to keep all full range applications in 4 ohm for better sound and actually louder and clearer sound. I run subs in 2 ohm. Takes a lot of amps and a lot of channels, but it it well worth it to keep the full range in 4 ohm.

2 ohm stables seem to cut out on those 100 degree days when played hard. I even have a custom installed fan system and I was stll dropping a PPI 4125 that was simply biwired separate to the tweets and the mids on 2 tower cannisters.

If you are looking for real loud, fork over the dough and get amps with 300 watts per channel to drive tower speakers and adjust gains accordingly. This will be loud, clean, and will eliminate concerns about heating and clipping.

*********************************************** **

I'm thinking about upgrading the tower speakers to the Defcon III's. These can be wired either daisy chained and run with a two channel amp or hooked up "normal" if you have a 4 channel amp. What would be the advantages of going 2 channel vs. 4 channel amp for this application

4 Channel without a doubt. Get a four channel that deliever 150 to 200 watts per channel in 4 ohm and you will be set. If you go two channel, you will lose some SQ, your amp will run hotter ffecting your curve, will sound brighter and will be prone to overheating, cutting out or clipping.

With towers, you you will very likely have a tendancy to push those very hard. On a hot day, 2 ohm configuration probably will cutt out cause heat issues unless the gains are way down. Then you will be lacking the volume you may desire.
Old    Psyclone (cyclonecj)      Join Date: Jul 2001       03-09-2003, 6:50 PM Reply   
Heat is something that I didn't mention, thanks Doug. Definitely a big factor. Two ohms is dang near a dead short anyway! Amps are exponentially noisier at lower impedances, and noise problems with cheap cabling are exacerbated. One simple but oddball thing, it is better to mount your amps with the heatsink fins oriented vertically, they will dissipate heat more effectively. Assuming they fit that way, mine never seem to! I'm not pushing the envelope like Doug, my stuff is simple and relatively cheap (like me) On the subject of biwiring, if that means running two separate wires from the same source to two separate components (say mid and tweet not x'd over) that's another hoax. Use one wire, the electrons don't know or care which speaker they're going to. They can't turn the corner and go down the right wire. They go down both wires. In fact, the more wire you have, the more distortion you will have. Electrons bouncing through copper dissipate energy through heat. That makes audio frequency loss, distortion and noise. Hiss. And some HF loss from the branch inductance caused by the twist in the wire. It's distortion times 2. I can measure these effects with test equipment, minor that they are. Less wire = less distortion. The people that sell this stuff are mercenary about selling myths and will come up with anything to sell you more 5$ a foot wire. In practice, none of this stuff makes much difference on a boat, but spending money unnecessarily is something we can all relate to.

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