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Post by wildgoose on May 23, 2016 16:09:28 GMT -5
I am hearing a subtle, but somewhat noticeable difference between the gen2 XPA-2 and the gen2 XPA-5. I am curious to know why the difference exist, and what makes the XPA-2 a better sounding amp.
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stiehl11
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Post by stiehl11 on May 23, 2016 16:17:04 GMT -5
I have the Gen 1 XPA-2 and XPA-5 and I heard similar differences between the 2 amps. When I talked to Lonnie in 2011 about the phenomenon, he said that, other than the XPA-1, the XPA-2 had the most unique sonic signature of the XPA line (at that time). There was very little changed from Gen 1 to Gen 2; namely cosmetics and the change in gain from 32db to 29db. So, I would imagine that the sonic signature of the XPA-2 remained mostly unchanged.
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Post by wildgoose on May 23, 2016 16:51:17 GMT -5
... he said that, other than the XPA-1, the XPA-2 had the most unique sonic signature of the XPA line (at that time). So the difference is due to sonic signature? Is it something that can be explained in a scientific/engineering manner?  |
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Post by sahmen on May 23, 2016 17:08:34 GMT -5
How about power?: They both use the same type of toroidal transformer, but the XPA-2, which serves fewer channels, can deliver more oomph to each channel than the XPA-5? I know this cannot be the whole explanation, although I do not think the difference is insignificant. I wish I had the technical nous to compare other significant factors, such as crosstalk, between the two amps, but the expertise is lacking, although I can also hear the difference between the two units (in my case, they're both Gen 1)
Here are some stats for the Gen 2 models gathered from the user manuals. :
XPA-2 : In Stereo Mode, the new XPA-2 delivers 300 watts per channel into 8 ohms and 500 watts per channel
into 4 ohms, both channels driven, at less than 0.1% THD+N.
Power Supply:
45,000 uF of storage capacitance.
1200 VA heavy duty toroidal transformer.
XPA-5 : The new XPA-5 delivers 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms, all
channels driven, at less than 0.1% THD+N.
Power Supply:
60,000 uF of storage capacitance.
1200 VA heavy duty toroidal transformer
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Post by repeetavx on May 23, 2016 17:16:31 GMT -5
The difference is output impedance. The XPA-2 has 12 output devices (transistors) per channel, in contrast to the 6 output devices per channel of the XPA-5
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Post by wildgoose on May 23, 2016 17:22:35 GMT -5
I too think it might have something to do with the power, based on what I am hearing. Perhaps with more power, the xpa-2 is driving my speakers more effortlessly, hence more punch to the bass. Still, it kinds of feels like hand waving and saying "the sound is warmer".  With more power, I wonder if the xpa-2 is driving the speaker at louder level than the xpa-5? How would one measure and compensate for the difference, if any? |
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Post by wildgoose on May 23, 2016 17:26:48 GMT -5
The difference is output impedance. The XPA-2 has 12 output devices (transistors) per channel, in contrast to the 6 output devices per channel of the XPA-5 Can you explain this a bit more? What does having more transistors do? I noticed that the XPA-2 have 12 caps, while the XPA-5 only had 6. But XPA-5 have more storage capacity specs, so I assume the XPA-5 uses larger caps. Is this related to the 12 output device/transistors you are talking about? |
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Post by repeetavx on May 23, 2016 19:44:11 GMT -5
More output devices means that the amplifier has a lower output impedance. Which makes it easier to handle back current, which is counter EMF. This allows the amplifier to control the speaker more precisely. Resulting in a more complex sound.
For comparison, the XPA-1 has 24 output devices per channel.
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Post by sahmen on May 23, 2016 20:15:10 GMT -5
More output devices means that the amplifier has a lower output impedance. Which makes it easier to handle back current, which is counter EMF. This allows the amplifier to control the speaker more precisely. Resulting in a more complex sound. For comparison, the XPA-1 has 24 output devices per channel. I cannot find the stats for "output impedance" or output devices in the specs provided in the manuals for both units. Could you kindly point me to some place where I might find this information? Thanks. |
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Post by repeetavx on May 23, 2016 20:17:18 GMT -5
They're over at the EmoVault. When I get home, I'll link to them.
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Post by sahmen on May 23, 2016 20:52:24 GMT -5
^^^Cool
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Post by rbk123 on May 23, 2016 21:42:04 GMT -5
XPA-2 : In Stereo Mode, the new XPA-2 delivers 300 watts per channel into 8 ohms and 500 watts per channel
into 4 ohms, both channels driven, at less than 0.1% THD+N. Power Supply:45,000 uF of storage capacitance. 1200 VA heavy duty toroidal transformer.XPA-5 : The new XPA-5 delivers 200 watts per channel into 8 ohms and 300 watts per channel into 4 ohms, all channels driven, at less than 0.1% THD+N.
Power Supply:60,000 uF of storage capacitance. 1200 VA heavy duty toroidal transformer The XPA-5 is assuming all channels driven. If only 2 channels, I imagine it has the same or very close power. |
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stiehl11
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Post by stiehl11 on May 23, 2016 22:08:38 GMT -5
... he said that, other than the XPA-1, the XPA-2 had the most unique sonic signature of the XPA line (at that time). So the difference is due to sonic signature? Is it something that can be explained in a scientific/engineering manner? Ask the engineer; I did, and I quoted what he said to me. I know that I noticed a very real difference between the 2 amps. I didn't buy the XPA-2 expecting to hear a difference, I just wanted an extra 2 channels. I took the XPA-2 over the UPA-2 because one came up for just a few dollars more on the used market. There is a significant difference in sound, however, between the UPA-2 and the XPA-2. |
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Post by repeetavx on May 24, 2016 11:03:02 GMT -5
They're over at the EmoVault. When I get home, I'll link to them. This information is archived from the Gen. 1 specs. The difference between Gen. 1 and Gen. 2 is the voltage gain. 32 db for the Gen. 1 vs 29 db. for the Gen. 2. Also the Gen. 2 utilizes more "surface mount" devices which helps lower the noise floor. The topography of these two generations is virtually the same. XPA-1XPA-2XPA-5 |
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Post by repeetavx on May 24, 2016 11:43:41 GMT -5
The XPA-5 is assuming all channels driven. If only 2 channels, I imagine it has the same or very close power. Here's some more interesting information. But that would happen with any single power supply multi channel amp. If you drive fewer channels the WPC goes up. It did with the XPA-5. Here are some Gen1 XPA-5 specs: 200 watts RMS/channel into 8 ohms, all channels driven 5 channels - 8 ohm = 200 watts per channel 4 channels - 8 ohm = 230 watts per channel 3 channels - 8 ohm = 250 watts per channel 2 channels - 8 ohm = 275 watts per channel 1 channel - 8 ohm = 300 watts per channel 4 ohm rating: 5 channels - 4 ohm = 350 watts per channel 4 channels - 4 ohm = 375 watts per channel 3 channels - 4 ohm = 400 watts per channel 2 channels - 4 ohm = 450 watts per channel 1 channel - 4 ohms = 500 watts per channel |
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Post by wildgoose on May 24, 2016 14:40:58 GMT -5
Is the number of channels dynamic based on whether there's input signal, or static based on number of speaker hookup?
ie, 5 speakers wired up, but listen in stereo mode, 275 watts or 200 watts?
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Post by wildgoose on May 24, 2016 15:22:21 GMT -5
Anyone know how many devices/ch the sa-250 has?
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Post by benbvan on May 24, 2016 17:05:54 GMT -5
I wonder how many the Gen 3 units have per channel?
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Post by repeetavx on May 24, 2016 17:48:37 GMT -5
Is the number of channels dynamic based on whether there's input signal, or static based on number of speaker hookup? ie, 5 speakers wired up, but listen in stereo mode, 275 watts or 200 watts? I believe that those are dynamic readings. |
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Post by repeetavx on May 24, 2016 17:49:58 GMT -5
Anyone know how many devices/ch the sa-250 has? Never been stated, and I haven't been able to get a count from the pictures. |
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