RE: Adcom 5500 vs Emotiva XPA-2

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Posted by John Elison (A) on September 22, 2015 at 23:24:32

In Reply to: Adcom 5500 vs Emotiva XPA-2 posted by slovell1 on September 22, 2015 at 17:18:37:

There is something I find very odd about the Emotiva XPA-2 amplifier from looking at the pictures in the webpage at the link below. It appears to have twelve 15,000-uF, 50-V capacitors in the power supply. The specifications state that power supply filter capacitance is 45,000-uF. The thing I find very odd is it appears that the twelve capacitors are used in series pairs to filter the rail voltage. This is extremely unusual and I have a feeling it's not a very good idea. The rail voltage is probably at least 70-volts if the amplifier is designed for 300-watts RMS into 8-ohms.

Power = Voltage²/Resistance

Therefore:

RMS Voltage = Square Root(Power x Resistance)
...................... = Square Root(300 x 8)
...................... = 49-volts RMS

This equates to 49 / 0.707 = 69.3-volts peak, which means the rails must be at least 70-volts.

I think 45,000-uF is too skimpy for an amplifier this large. My Parasound Halo A-21 is rated at 250-wpc RMS into 8-ohms and it has 70-volt rails with 100,000-uF filter capacitance as well as a 1200-VA toroidal transformer. Of course, the Parasound costs more than double the price of the Emotiva. Still, I think the Emotiva XPA-2 power supply filter is poorly designed with less than sufficient capacitance.

The Adcom GFA-5500 has a 1500-VA toroidal transformer. I couldn't find out its power supply filter capacitance, but I have a feeling it might be the better amplifier.

Best regards,
John Elison

Emotiva XPA-2 (Open in New Window)

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Follow Ups Full Thread

Topic - Adcom 5500 vs Emotiva XPA-2 - slovell1 17:18:37 09/22/15 (15)

RE: Adcom 5500 vs Emotiva XPA-2 - fantja 05:10:42 09/23/15 (2)

RE: Adcom 5500 vs Emotiva XPA-2 - slovell1 15:53:28 09/23/15 (1)

RE: Adcom 5500 vs Emotiva XPA-2 - bboroski 10:06:53 09/24/15 (0)

RE: Adcom 5500 vs Emotiva XPA-2 - bboroski 04:49:59 09/23/15 (5)

Nice - mjcmt 04:15:28 09/24/15 (4)

RE: Nice - slovell1 15:07:38 09/27/15 (3)

RE: Nice - Mr Peabody 20:52:13 09/27/15 (2)

RE: Nice - caustic386 03:15:24 10/01/15 (1)

RE: Nice - Mr Peabody 05:08:30 10/01/15 (0)

RE: Adcom 5500 vs Emotiva XPA-2 - John Elison 23:24:32 09/22/15 (4)

RE: Adcom 5500 vs Emotiva XPA-2 - mjcmt 04:17:58 09/24/15 (3)

Thanks! - John Elison 00:40:08 09/25/15 (2)

RE: Thanks! - ejman 10:07:43 09/25/15 (1)

I'm guessing - E-Stat 11:41:02 09/25/15 (0)

RE: Adcom 5500 vs Emotiva XPA-2 - pictureguy 18:50:58 09/22/15 (0)

Follow Ups

RE: Adcom 5500 vs Emotiva XPA-2 - John Elison 23:24:32 09/22/15 (4)

RE: Adcom 5500 vs Emotiva XPA-2 - mjcmt 04:17:58 09/24/15 (3)

Thanks! - John Elison 00:40:08 09/25/15 (2)

RE: Thanks! - ejman 10:07:43 09/25/15 (1)

I'm guessing - E-Stat 11:41:02 09/25/15 (0)

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