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Post by nickwin on Jan 25, 2018 10:26:43 GMT -5
I can agree we all have different outcomes or views on amps, for myself owning the XPA-5 in both gens, an XPA-3, XPA-2 and my now PA 7-350 I have noticed zero difference in any of them regardless how many channels I am using, my speakers have been Monitor Audio silver series and my Chane A5rx-c's. I did however notice a difference in sound signature in the UPA series from the XPA series, I have owned the UPA-500, UPA-200 and UPA-1's, and one interesting thing is when I had my USP-1 I actually preferred using the UPA-500 to the UPA-1's for 2ch music. Chad You know, despite its technical shortcoming, I really like the UPA500 for stereo too! I always felt like the UPA (2 and 5) where a little dark and laid back and the XPAs slightly forward and edgy. The UPA500 seemed to sit right in the middle and didn't really have any "sound" of its own. That was my take any way. Honestly, I only hear good thing about the upa500. Emotiva seems to have done a lot with very little with this amp. |
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KeithL
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Post by KeithL on Jan 25, 2018 10:40:45 GMT -5
I would correct you on one specific detail. The vast majority of multi-channel Class A/B power amps do in fact share one transformer between multiple channels. (Virtually none are regulated - like the supply in our new XPA Gen3.) Many older high-end stereo models had two separate transformers, or one transformer with two secondaries, and separate rectifiers and filters. And some modular multi-channel designs, including some of our older models, have a separate power supply in each module. However, I don't recall ever seeing a non-modular surround sound amp with a separate transformer for each channel (although I'm sure a few models do exist). NOTE that this arrangement is quite common with modern Class D designs..... where several of the current amp modules include an individual Class D power supply. Cooling depends on several things, including heat sink surface area, spacing, vent size, and the dynamics of air flow inside the unit. In order to avoid fans, you basically have to ensure that, as the units warms up, the hot air will rise out the top, and pull cool air in through the bottom and sides, and that the incoming cool air will pass across the heat sinks rather than bypassing them entirely. This can be tricky because, without a fan, the volume of air involved is relatively small, and it moves relatively slowly under low pressure, so it must be utilized for cooling as efficiently as possible. If we use say Channel 1 and Channel 5 in an XPA-5 then both of the boards are further away from the transformer (mounted front and centre) than Channel 1 or 2 in an XPA-2 (mounted dead centre of the chassis). Each channel in the XPA-5 has its own input stage, so the Channel 1 input stage is no closer to the Channel 5 input stage than the inputs stages in Channel 1 and 2 in an XPA-2. The internal wiring is really only for the power supply, as the inputs and output from each channel are located on that channel's board (ie; no other "wiring"). The XPA-5 power supply is located at the front, so the wiring run to the boards for each channel is very short. The XPA-2 power supply is located in the centre, so the wiring run to the boards for each channel is equally as short. The XPA-2 definitely has longer heat sinks, located down each side of the case. But having owned both I can't say that the XPA-5 runs any hotter ie; both have adequate heat sinks. Provided no overheating there wouldn't be any sound quality difference due to heat sink differences. Looking at them, it's obvious to me that Lonnie and the guys have done a great job optimising the internal layouts so as to minimise any interference issues. Cheers Gary To each there own! As much as I wanted to be I was never happy with the xpa5 for 2 channel. Also, it would be very odd if the crew at Emotiva couldn’t capitalize AT ALL on the inherent advantages of a two channel amp compared to a 5 channel amp with the same size case, transformer and basically budget. With only $99 to work with on those 3 addition channels they would have had to been REALLY lazy with the xpa2 design to not get ANYTHING extra out of it. Another thing to keep in mind is the XPA3 is not the same as the 2 and 5. The 5 May hold its own with the 2 in 2 channel but the 3 absolutely will not. Like I said before, in the case of most Emotiva amps, because they use a shared PS, It may be very close, but a shared PS is NOT the norm in the industry. In general most multi channel amps use independent supplies, or at least independent windings, and in most cases the mono and stereo amps will have more robust PS than the multichannel amps in the same line (per channel). With Emotiva it may be close, but with many brands it won’t. Something for the OP to keep in mind At the end of the day everybody hears things differently and that’s the nature of the hobby. This is just what I hear. Enjoy the journey OP! Anything mentioned in this thread will be a step up from your AVR. |
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Post by nickwin on Jan 25, 2018 10:43:52 GMT -5
I would correct you on one specific detail. The vast majority of multi-channel Class A/B power amps do in fact share one transformer between multiple channels. (Virtually none are regulated - like the supply in our new XPA Gen3.) Many older high-end stereo models had two separate transformers, or one transformer with two secondaries, and separate rectifiers and filters. And some modular multi-channel designs, including some of our older models, have a separate power supply in each module. However, I don't recall ever seeing a non-modular surround sound amp with a separate transformer for each channel (although I'm sure a few models do exist). NOTE that this arrangement is quite common with modern Class D designs..... where several of the current amp modules include an individual Class D power supply. Cooling depends on several things, including heat sink surface area, spacing, vent size, and the dynamics of air flow inside the unit. In order to avoid fans, you basically have to ensure that, as the units warms up, the hot air will rise out the top, and pull cool air in through the bottom and sides, and that the incoming cool air will pass across the heat sinks rather than bypassing them entirely. This can be tricky because, without a fan, the volume of air involved is relatively small, and it moves relatively slowly under low pressure, so it must be utilized for cooling as efficiently as possible. To each there own! As much as I wanted to be I was never happy with the xpa5 for 2 channel. Also, it would be very odd if the crew at Emotiva couldn’t capitalize AT ALL on the inherent advantages of a two channel amp compared to a 5 channel amp with the same size case, transformer and basically budget. With only $99 to work with on those 3 addition channels they would have had to been REALLY lazy with the xpa2 design to not get ANYTHING extra out of it. Another thing to keep in mind is the XPA3 is not the same as the 2 and 5. The 5 May hold its own with the 2 in 2 channel but the 3 absolutely will not. Like I said before, in the case of most Emotiva amps, because they use a shared PS, It may be very close, but a shared PS is NOT the norm in the industry. In general most multi channel amps use independent supplies, or at least independent windings, and in most cases the mono and stereo amps will have more robust PS than the multichannel amps in the same line (per channel). With Emotiva it may be close, but with many brands it won’t. Something for the OP to keep in mind At the end of the day everybody hears things differently and that’s the nature of the hobby. This is just what I hear. Enjoy the journey OP! Anything mentioned in this thread will be a step up from your AVR. Hmm, I know all the Parasound amps use independent secondaries and I thought all the ATI (Monolith & Outlaw) and most Anthem amps did too? The point I was trying to make is that you can't assume all multichannel amps are going to have one completely shared PS. There are MANY amps on the market that do not. Just between all the Parasound and ATI (Monolith, Outlaw etc) and many of the Anthem amps in circulation it has to be a pretty big chunk. Majority might have been a stretch though...Previous post edited. I do understand that separate secondary windings is not the same thing as completely separate transformers, but in the context of how much power a multichannel amp will put into 1-2 channels, seperate secondary winding still make a huge difference. EDIT: It looks like Anthem has just started using one shared PS on the current generation MCA amps but the older MCAs and the higher end models still use independent windings (P5). All the ATI made amps do indeed appear to use independent secondaries as well. |
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Post by leonski on Jan 26, 2018 18:41:37 GMT -5
One other major factor in heat sink sizing and design is class of operation. 'A' amps will need huge amounts of heat sink, in part accounting for the huge weight to power ratio.
And not that it really matters, but some of the real, overachiever 7 channel amps need 2x 15 amp plugs on SEPERATE CIRCUITS.
As for 'robustness' of PS? You are still limited by power supplied by the circuit, with a 20% derate for long-time period delivery. Factor in amp efficiency and you are at a hard, upper limit for long term power delivery.
And yes, a 15 amp circuit will deliver lots more current for short time periods, but I'm curious as to the voltage at that point.
And it must also be noted that MOST bench tester guys will use a Variac to stabilize line voltage to some nominal value when 'red line' testing an amplifier.
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