ARC KS300.2 vs. KS300.4 efficiency
 

According to the table published by ARC Audio, the 300.2 is much more efficient, while delivering the same power. Is this a typo? See page 14 of the below PDF.

http://www.arcaudio.com/product-pdf/KS300_24-V2.pdf

I am running four tower speakers, each at 4 ohms. I was planning on running a 300.4 bridged in stereo mode. But after looking at ARC's specs, I would be much better off running a 300.2 in mono mode at 4 ohms.

Because of the environment and lack of space between the speakers, I see no benefit to running these speakers in stereo.... Especially considering how much more efficient the 300.2 is supposed to be. This should equate to being much easier on my electrical system and giving me an extended play period.


Summary of the info on ARC's website:

300. 2 Power Output at 4Ohm Bridged: 700 watts @ 68A, Eff 71%

300.4 Power Output at 4Ohm Bridged: 350 watts x 2, @ 132A, Eff 53%


It appears that the 300.2 is more efficient at all impedance loads... Does this make sense?

Mike, you can't bridge the two channels on the 300.2 and run two speakers expecting to get 350x2.

If the 300.2 is bridged, it certainly won't put out 350x2... But what it will put out is 700w x 1 at 4 ohms.... So if your speakers are wired right, and can present the amp with a 4 ohm load, the 700 watts is divided between the number of drivers. Basically if I were to use this amp, I would be running my tower speakers in mono.

Sure it will - bridged to one speaker. Tons of people run a single sub of the 300.2

Like I said - you will not get that amp to run 2 speakers at the 4ohm/700 watt load.

This may help you further. It is from the Wetsounds Amps since they are built on the Arc Ks platform.

Tower Speakers:
- (1) pair of PRO 60's or (1) pair of PRO 80's. Power: 200 x 2.
- (2) pairs of PRO 60's or (2) pairs of PRO 80's. Power: 350 x 2
- DOUBLE UP tower system: Power: 350 x 2.

Subwoofers:
- (1) XS-XXX at 4 ohms. Power: 700 x 1.
- (2) XS-10FA D4 subwoofers at 4 ohms or (2) XS-12 D4 subwoofers at 4 ohms. Power 700 x 1


As you can see you would need dual 4ohm tower speaker to run at mono and get 700x1. Tower speakers do not have dual voice coils.

Well it would depend on the impedance of the speakers... My original post actually said running four speakers (They're actually two housings, each one with two drivers - Each driver is a 4 ohm speaker.)

Under the above configuration, Each cabinet/housing could be wired to have a 8 ohm load... Then when the two cabinets are wired together, they can produce a single 4 ohm load.


My main question with my post was related to the efficiency ratings of the 300.2 vs the 300.4... I was shocked to see the difference between the two.

Those two amps will not deliver the same power to your four speakers, so efficiency is irrelevant IMO.

The 300.4 is 90W x 4 @ 4 ohm, so that 90W to each of your 4 speakers.

The 300.2 is 350W x 2 @ 2 ohm, so thats 175W to each speaker.

Or wire the two speakers in each pod in parallel to 2 ohms and run each pod on its own chnl of the 300.2. Nets the same 700W.

Mike,

You can run either amp.

The wiring options with the 300.2 are:
- series-parallel the tower to one 4 ohm load with the amp driving 700 watts / 4 speakers or 175 watts to each speaker. this way you only need to bring one pair of wire down from the tower but you get mono out of the tower which is fine for most people
- parallel 2 speakers on left, parallel 2 speakers on right. amp driving 350 watts / 2 speakers or 175 watts to each speaker. another pair wires but this setup gets you stereo on the tower

The wiring options for the 300.4 are:
- one speaker per channel, 90 watts per speaker. wiring mess with 4 pairs of unnecessary wiring
- series 2 speakers on left, series 2 speakers on right, amp 1/2 bridged to left, amp 3/4 bridged to right. this will get you 175/2 or 87.5 to each speaker. this will require 2 pairs of wires. basically the exact same as the above.

so the easy choice is the 300.2 since it is cheaper and will provide more power to each speaker.

You could also consider the JL HD 750/1 amp running the 4 ohm load. Talk to David from Earmark about it.

Fozz - my bad, i thought you were running 2 tower speakers.

I run the 300.2 to 4 pro 80's and really like that amp.

As for efficiency, since both amplifiers are using the identical topology I don't see why the efficiency isn't the same or very close. The Arc mono amplifier and six-channel amplifier use different topologies from the two in discussion so those may have a little different efficiency. Also, efficiency will vary for the same amplifier according to the load impedance as well as in the bridged mode. Its not a constant. Consider that a misprint.
As for the JL Audio HD750/1, keep in mind that the new JL Audio HD1200/1 is also rated as fullrange with both a highpass and lowpass active crossover. Highly efficient Class D, strictly regulated in all respects so it delivers its full 1200 watts at any practical voltage supply and at any practical impedance load. That's 300 watts to each of four tower HLCDs. Contrastly, unregulated amplifiers may lose 20 to 25 percent of their rated 14.4 volt power as the supply sags to 12.5 volts. The JL Audio HD1200/1 generates 1200 watts under all conditions when correctly put to task. This could make the HD1200/1 the largest tower amplifier available by a comfortable margin as well as a pretty serious subwoofer amplifier.

David
Earmark Marine

OOH!!! That sounds bad ass David.

2 JL Audio HD 1200/1 to a pair of Rev 485's.

I think I will hold out for that setup

You're ahead of me. I was thinking one with 2 pair of Rev10's.

53% doesn't sound to efficient to me. These are talked about like the holy grail of amplifiers.

Murph you better refi your house to pay for that one.

1 to 2 pairs of rev 10's
1 to a XXX or another sub of choice
1 750/1 to 2 pairs of XS650's

David the JL HD 1200/1 is good choice for this tower set up. The other possibility is to use Zed's Dreadnought in bridged mode - 800w x 2. This would send 400 watts to each tower HLCD. Next we are a installing a Dreadnought and a Draconia II for total of 2400 watts to power our tower six-some.
Marc
Liquid Acoustics

Marc,
I'm not sure I understand. The Dreadnought would do 4 times 225 watts at 4-ohms. If you bridge it into a seriesed 8-ohm load you would still get 225 watts per each of four tower speakers. Are you advocating bridging the Zed Dreadnought into a 2-ohm load to drive four 4-ohm tower speakers, two in parallel per channel, in July?

David
Earmark Marine

David,
You're right. I, missed the part of 4 at 4 ohms and in this case JL HD 1200/1 is a perfect match. We will have 4 enclosures on our tower. 2 will be duals at 4 ohms and 2 singles at 4 ohms. Each dual will be loaded with 2 mids,& 2 HLCD. This combination gives us 6 mids & 6HLCD in total.