Post by Jim on Jul 8, 2012 17:14:45 GMT -5
I created this FAQ to answer from general questions about the XPR-5 that have been asked by new owners and prospective customers. It's not official by any means, so please take it with a grain of salt. I'm happy to try to grow the FAQ and add questions and answers as they arise. EDIT: I own an XPR-5 now. Great amp!
Unofficial XPR-5 FAQ
Basics:
What is the weight?
94 lbs (net); 107 lbs (boxed)
What are the dimensions?
17" wide x 9.5" high x 19.5" deep (includes feet and binding posts; requires additional 3-4" of depth clearance to accommodate the power cord).
What is the rated power?
400 watts / channel (x5); all channels driven; into 8 Ohms.
600 watts / channel (x5); all channels driven; into 4 Ohms.
500 watts / channel (x2); two channels driven; into 8 Ohms.
750 watts / channel (x2); two channels driven; into 4 Ohms.
575 watts / channel (x1); one channel driven; into 8 Ohms.
1100 watts (1 .1 kW) / channel (x1); one channel driven; into 4 Ohms.
What is the input sensitivity?
1.875v
What is the gain?
29db
How many output devices are there?
Each PWB (channel/module) contains 12 devices. On each PWB there are 6 on the top and 6 on the bottom. There are a total of 60 output devices (12 devices x 5 channels).
Does the XPR-5 have fans?
The XPR-5 is passively cooled with substantial heatsinking (Much like the XPA series). It has no fans (unlike the Mini-X A-100 or UPA500 that do have fans that turn on under load).
Is it class A/B or Class H/D/E/F/G/I?
To quote Dan Laufman (from emotivalounge.proboards.com/index.cgi?action=gotopost&board=amps&thread=24997&post=417104 )
"All Class H amplifiers typically have a Class AB amplifier as the gain element.
The Class H refers to the power supply topology, so it's all in how you choose to look at it. If you turn off the Class H rail switching, the Class H amp is now a Class AB amp.
We have a two rail design in the XPR-5. The low rail, which is what the amp is powered from on idle up to about 50% of the amps voltage swing, and then the high voltage rail with takes it all the way to maximum output. By sitting on the lower rail most of the time, quiescent losses are greatly reduced. The amp runs really cool under normal operation.
But when you need it, the rails instantly switch to the high voltage mode and presto, a beast is born! There is a high speed comparator that looks at the input signal and predicts where the output is going, and when needed, it turns on the high voltage rail BEFORE the output gets there. You can't fool it, even with high frequency transients, as its switching time is faster than the rise time of a 20kHz signal. Sweet!
So, you get the SQ of a really well designed Class AB amp, with a huge efficiency improvement, and no sonic downside.
We've been building Class H amps for a long, long time and we have the control loop down pat. It's more expensive than Class AB, but at a certain power level, it's just the only way to go. You can't justify the power losses on an amp this big.
There is really no down side to a well designed Class H amp. But remember, it's all in the details. You have to start with a great sounding amplifier stage. And the Class H controller has to be done very carefully in order to minimize sonic artifacts. When done correctly, (like in the XPR-5) the result is amazing."
What does the "Peak" button on the front panel do?
The peak button changes the meter between showing peak levels in real time and peak hold.
What does the "Dim button on the front panel do?
It dims the LEDs. There are 5 different brightness levels.
What does the "Meter" button on the front panel do?
It cycles through the following scenarios:
1. Bargraph Meters + Status LEDs on + Accent Lighting on (Default)
2. Status LEDs only
3. All lights off (Power LED remains on at a dim level)
4. Status LEDS only
5. Status LEDs + Accent lighting
Where can I see what the meter looks like and what the front panel buttons do?
See here: emotivalounge.proboards.com/index.cgi?board=amps&action=display&thread=25051
How many LEDs does each channel have on the front meter?
I believe that each channel has 12 bicolor (red/blue) LEDs. (Needs confirmation. Some pictures seem to make it appear that it has less.)
Why is it so heavy?
Mostly because of the hefty 3300 VA torroid transformer (It's massive, weighing 45-50lb). Then there is the weight due to 180,000uF of capacitance and 5 channels capable of 2000W+ of class A/B power.
How much power does it use while powered on and idle (no signal)?
Based on my personal measurements, between 65 and 85 watts.
How warm is it while sitting powered on and idle?
Based on my personal measurements, the top of the case measures 10-15 degrees warmer than ambient - barely warm to the touch.
Want More technical specs?
See the store page: shop.emotiva.com/collections/amplifiers/products/xpr5
Rack mounting considerations:
Height:
The XPR-5 is 5 RU tall, but requires clearance above and below for ventilation. (How much probably depends on the rack's ventilation, but at least 2U above would probably be a good start and 1U below to clear the feet and allow air flow to the bottom). So ballpark, at least 8 RU total.
EDIT: Some people have reported that they have been running OK with 1" of clearance above and that the XPR-5 may run cooler than a XPA-1. 1U (1.75") of clearance above may be safe, but I'd recommend monitoring temps to be sure.
Mounting:
There is no information currently regarding the availability of rack ears.
Power related:
What are the power requirements?
From Emotiva's website: 115 VAC or 230 VAC +/- 10% @ 50 / 60 Hz (user selectable).
The XPR-5 requires a 20 Amp circuit and standard IEC 20 Amp outlet (which is different than a 15 Amp outlet).If you don’t have a proper circuit and outlet, we recommend you have one installed by a qualified electrician.We recommend that the XPR-5 be plugged into its own dedicated 20 Amp circuit.
From a post by Lonnie:
emotivalounge.proboards.com/index.cgi?action=gotopost&board=amps&thread=25104&post=419846
"Several people have asked why we use the 20 amp IEC cords. Well the simple answer is that is what was required for it to pass safety certification because they test the amp at balls to the walls full power with sign waves (a condition that would never be done in real life, but that is what they do). Since it was tested and certified that way, we are obligated to ship it with the same cord."
Why does the XPR-5 need a 20A outlet?
Because the XPR has a HUGE 3300 VA transformer that can exceed the current that a 15a outlet can provide.
What about Australian customers? Should I use a 20A outlet too?
The recommendation is that Australian customers use a 20A outlet as well - consistent with the 20A IEC receptacle on the back of the XPR-5.
What can I do if I don't have a 20A outlet and want to fire it up on a 15A circuit?
You can buy an 20A outlet to 15A outlet adapter. (Something like this: www.sweetwater.com/store/detail/ADP1520/) Note: While this may work fine for music, if you push the XPR-5 or do measurements, you will NEED a 20A outlet. Emotiva recommends 20A service for a reason.
I'm not running it on a 20A breaker and the breaker just tripped what do I do?
Contact an electrician and get a dedicated 20A circuit and outlet! Don't keep resetting the breaker - and don't simply replace the 15A breaker with a 20A one. (Related note, generally 12 gauge is larger is required for 20A service according to NEC. 14 gauge is not sufficient)
What does the supplied 20A plug look like?
How does a 15A outlet appear compared to a 20A outlet?
See here:
What does the XPR-5 end look like (IEC 20A plug)?
How does the receptacle on the back of the XPR-5 compare to other Emotiva amps?
The XPR-5 has a 20A IEC receptacle. Many other amps, computers, monitors, etc have a 15A receptacle.
Should I plug it into a power conditioner, UPS, or other magical power device?
Emotiva amps do not require surge protection or power conditioning. Generally the recommendation is not to use it - as it can easily become a limiting factor in supplying sufficient current.
What about hospital grade outlets?
If you're installing new outlets, you can install regular 20A outlets - or hospital grade 20A outlets. Hospital grade outlets are generally more sturdy and have better plug retention. (They also appear to be more resistant to chemical abuse). Whether you want to spend the extra money is up to you - but you can't go wrong either way. Hospital grade outlets would not normally be found in a residential house - unless specifically requested.
How much power does it use while powered on (active) but no signal? (ie, sitting idle)
It uses less than 100w.
Other useful information
Is the XPR-5 fully differential? Is it balanced?
The XPR-5 does have balanced connections, but is not fully differential. The XPA-1 and XPR-1 are.
KeithL wrote an excellent explanation:
There is a lot of confusion about what "differential" and "balanced" mean.
The term balanced is generally used to refer to connections. With a balanced connection, there are two "hot" leads, one of which carries "signal +" and the other "signal -", and the input is the DIFFERENCE between them. The great benefit is that and noise (like hum) that is picked up equally by both input signal leads cancels out. (Since you are subtracting the two inputs, and it is common to both of them, it subtracts to near zero.) This is called "common mode rejection". You can take this balanced signal and feed it to an amplifier that is "balanced", or not, and still get this benefit.
In order for an amplifier to be "differential", you need two entirely separate amplifier circuits, each driven out of phase from the other. When you do this, most of the distortion and some of the noise that is present equally in both amplifiers will cancel out. You usually end up with slightly lower distortion this way (how much you benefit depends on other design considerations). In a fully differential amplifier, NEITHER speaker binding post is grounded (they are "out +" and "out -").
In order for an entire system to be "fully balanced" AND "fully differential", all of the individual components would have to be differential and all of the connections balanced. So, for example, if you connect an XDA-2 to an XSP-1, and the XSP-1 to a pair of XPR-1's, using all balanced connections, and run the XSP-1 in Differential Reference mode (Tone trims off, etc), then the entire system would be balanced and differential.
The XPA-1, and the XPR-1 are fully differential amplifiers, and they have balanced inputs. The XPA-2, XPA-3, XPA-5, XPR-2, and XPR-5 are NOT differential amplifiers (the black speaker binding post IS grounded), but they do have balanced inputs.
What's the beef with damping factor? (This is non XPR-5 specific, but I thought very useful)
Another excellent write up, courtesy of KeithL:
The damping factor on all our amps is at least 500, and the differences between anything over about 100 are absolutely inaudible (and are difficult to even measure accurately in real-world situations).
If you look at the electrical models involved, the actual "delivered" damping factor is limited by the resistance of the speaker cables and the wire in the voice coils of your speakers. (A typical woofer has a DC resistance of about 2-3 ohms).
In the model, the internal resistance of the amplifier is ADDED TO the resistance of the speaker, then divided into the nominal resistance of the speaker. The internal resistance of an amplifier with a DF of 8 is 1 ohm; the internal resistance of an amp with a DF of 80 is 0.1 ohm, and that of an amp with a DF of 800 is 0.01 ohm.
So:
For an amp with the DF of 1, the *real* damping factor is 8/(8+3), which is about 0.7
For an amp with the DF of 8, the *real* damping factor is 8/(1+3), which is about 2
For an amp with the DF of 80, the *real* DF is 8/(.1+3), which is about 2.58
For an amp with the DF of 800, the *real* DF goes up to 8/(.01+3), which is 2.66
As you can see, going from a DF of 1 to a DF of 8 or 10 makes a huge difference (and those numbers are reasonable for tube amps), but anything past 100 or so doesn't make much difference at all (in fact, it gets really hard to measure over about 500, and the numbers may be different depending on what measurement method you use).
Unofficial XPR-5 FAQ
Basics:
What is the weight?
94 lbs (net); 107 lbs (boxed)
What are the dimensions?
17" wide x 9.5" high x 19.5" deep (includes feet and binding posts; requires additional 3-4" of depth clearance to accommodate the power cord).
What is the rated power?
400 watts / channel (x5); all channels driven; into 8 Ohms.
600 watts / channel (x5); all channels driven; into 4 Ohms.
500 watts / channel (x2); two channels driven; into 8 Ohms.
750 watts / channel (x2); two channels driven; into 4 Ohms.
575 watts / channel (x1); one channel driven; into 8 Ohms.
1100 watts (1 .1 kW) / channel (x1); one channel driven; into 4 Ohms.
What is the input sensitivity?
1.875v
What is the gain?
29db
How many output devices are there?
Each PWB (channel/module) contains 12 devices. On each PWB there are 6 on the top and 6 on the bottom. There are a total of 60 output devices (12 devices x 5 channels).
Does the XPR-5 have fans?
The XPR-5 is passively cooled with substantial heatsinking (Much like the XPA series). It has no fans (unlike the Mini-X A-100 or UPA500 that do have fans that turn on under load).
Is it class A/B or Class H/D/E/F/G/I?
To quote Dan Laufman (from emotivalounge.proboards.com/index.cgi?action=gotopost&board=amps&thread=24997&post=417104 )
"All Class H amplifiers typically have a Class AB amplifier as the gain element.
The Class H refers to the power supply topology, so it's all in how you choose to look at it. If you turn off the Class H rail switching, the Class H amp is now a Class AB amp.
We have a two rail design in the XPR-5. The low rail, which is what the amp is powered from on idle up to about 50% of the amps voltage swing, and then the high voltage rail with takes it all the way to maximum output. By sitting on the lower rail most of the time, quiescent losses are greatly reduced. The amp runs really cool under normal operation.
But when you need it, the rails instantly switch to the high voltage mode and presto, a beast is born! There is a high speed comparator that looks at the input signal and predicts where the output is going, and when needed, it turns on the high voltage rail BEFORE the output gets there. You can't fool it, even with high frequency transients, as its switching time is faster than the rise time of a 20kHz signal. Sweet!
So, you get the SQ of a really well designed Class AB amp, with a huge efficiency improvement, and no sonic downside.
We've been building Class H amps for a long, long time and we have the control loop down pat. It's more expensive than Class AB, but at a certain power level, it's just the only way to go. You can't justify the power losses on an amp this big.
There is really no down side to a well designed Class H amp. But remember, it's all in the details. You have to start with a great sounding amplifier stage. And the Class H controller has to be done very carefully in order to minimize sonic artifacts. When done correctly, (like in the XPR-5) the result is amazing."
What does the "Peak" button on the front panel do?
The peak button changes the meter between showing peak levels in real time and peak hold.
What does the "Dim button on the front panel do?
It dims the LEDs. There are 5 different brightness levels.
What does the "Meter" button on the front panel do?
It cycles through the following scenarios:
1. Bargraph Meters + Status LEDs on + Accent Lighting on (Default)
2. Status LEDs only
3. All lights off (Power LED remains on at a dim level)
4. Status LEDS only
5. Status LEDs + Accent lighting
Where can I see what the meter looks like and what the front panel buttons do?
See here: emotivalounge.proboards.com/index.cgi?board=amps&action=display&thread=25051
How many LEDs does each channel have on the front meter?
I believe that each channel has 12 bicolor (red/blue) LEDs. (Needs confirmation. Some pictures seem to make it appear that it has less.)
Why is it so heavy?
Mostly because of the hefty 3300 VA torroid transformer (It's massive, weighing 45-50lb). Then there is the weight due to 180,000uF of capacitance and 5 channels capable of 2000W+ of class A/B power.
How much power does it use while powered on and idle (no signal)?
Based on my personal measurements, between 65 and 85 watts.
How warm is it while sitting powered on and idle?
Based on my personal measurements, the top of the case measures 10-15 degrees warmer than ambient - barely warm to the touch.
Want More technical specs?
See the store page: shop.emotiva.com/collections/amplifiers/products/xpr5
Rack mounting considerations:
Height:
The XPR-5 is 5 RU tall, but requires clearance above and below for ventilation. (How much probably depends on the rack's ventilation, but at least 2U above would probably be a good start and 1U below to clear the feet and allow air flow to the bottom). So ballpark, at least 8 RU total.
EDIT: Some people have reported that they have been running OK with 1" of clearance above and that the XPR-5 may run cooler than a XPA-1. 1U (1.75") of clearance above may be safe, but I'd recommend monitoring temps to be sure.
Mounting:
There is no information currently regarding the availability of rack ears.
Power related:
What are the power requirements?
From Emotiva's website: 115 VAC or 230 VAC +/- 10% @ 50 / 60 Hz (user selectable).
The XPR-5 requires a 20 Amp circuit and standard IEC 20 Amp outlet (which is different than a 15 Amp outlet).If you don’t have a proper circuit and outlet, we recommend you have one installed by a qualified electrician.We recommend that the XPR-5 be plugged into its own dedicated 20 Amp circuit.
From a post by Lonnie:
emotivalounge.proboards.com/index.cgi?action=gotopost&board=amps&thread=25104&post=419846
"Several people have asked why we use the 20 amp IEC cords. Well the simple answer is that is what was required for it to pass safety certification because they test the amp at balls to the walls full power with sign waves (a condition that would never be done in real life, but that is what they do). Since it was tested and certified that way, we are obligated to ship it with the same cord."
Why does the XPR-5 need a 20A outlet?
Because the XPR has a HUGE 3300 VA transformer that can exceed the current that a 15a outlet can provide.
What about Australian customers? Should I use a 20A outlet too?
The recommendation is that Australian customers use a 20A outlet as well - consistent with the 20A IEC receptacle on the back of the XPR-5.
What can I do if I don't have a 20A outlet and want to fire it up on a 15A circuit?
You can buy an 20A outlet to 15A outlet adapter. (Something like this: www.sweetwater.com/store/detail/ADP1520/) Note: While this may work fine for music, if you push the XPR-5 or do measurements, you will NEED a 20A outlet. Emotiva recommends 20A service for a reason.
I'm not running it on a 20A breaker and the breaker just tripped what do I do?
Contact an electrician and get a dedicated 20A circuit and outlet! Don't keep resetting the breaker - and don't simply replace the 15A breaker with a 20A one. (Related note, generally 12 gauge is larger is required for 20A service according to NEC. 14 gauge is not sufficient)
What does the supplied 20A plug look like?
How does a 15A outlet appear compared to a 20A outlet?
See here:
What does the XPR-5 end look like (IEC 20A plug)?
How does the receptacle on the back of the XPR-5 compare to other Emotiva amps?
The XPR-5 has a 20A IEC receptacle. Many other amps, computers, monitors, etc have a 15A receptacle.
Should I plug it into a power conditioner, UPS, or other magical power device?
Emotiva amps do not require surge protection or power conditioning. Generally the recommendation is not to use it - as it can easily become a limiting factor in supplying sufficient current.
What about hospital grade outlets?
If you're installing new outlets, you can install regular 20A outlets - or hospital grade 20A outlets. Hospital grade outlets are generally more sturdy and have better plug retention. (They also appear to be more resistant to chemical abuse). Whether you want to spend the extra money is up to you - but you can't go wrong either way. Hospital grade outlets would not normally be found in a residential house - unless specifically requested.
How much power does it use while powered on (active) but no signal? (ie, sitting idle)
It uses less than 100w.
Other useful information
Is the XPR-5 fully differential? Is it balanced?
The XPR-5 does have balanced connections, but is not fully differential. The XPA-1 and XPR-1 are.
KeithL wrote an excellent explanation:
There is a lot of confusion about what "differential" and "balanced" mean.
The term balanced is generally used to refer to connections. With a balanced connection, there are two "hot" leads, one of which carries "signal +" and the other "signal -", and the input is the DIFFERENCE between them. The great benefit is that and noise (like hum) that is picked up equally by both input signal leads cancels out. (Since you are subtracting the two inputs, and it is common to both of them, it subtracts to near zero.) This is called "common mode rejection". You can take this balanced signal and feed it to an amplifier that is "balanced", or not, and still get this benefit.
In order for an amplifier to be "differential", you need two entirely separate amplifier circuits, each driven out of phase from the other. When you do this, most of the distortion and some of the noise that is present equally in both amplifiers will cancel out. You usually end up with slightly lower distortion this way (how much you benefit depends on other design considerations). In a fully differential amplifier, NEITHER speaker binding post is grounded (they are "out +" and "out -").
In order for an entire system to be "fully balanced" AND "fully differential", all of the individual components would have to be differential and all of the connections balanced. So, for example, if you connect an XDA-2 to an XSP-1, and the XSP-1 to a pair of XPR-1's, using all balanced connections, and run the XSP-1 in Differential Reference mode (Tone trims off, etc), then the entire system would be balanced and differential.
The XPA-1, and the XPR-1 are fully differential amplifiers, and they have balanced inputs. The XPA-2, XPA-3, XPA-5, XPR-2, and XPR-5 are NOT differential amplifiers (the black speaker binding post IS grounded), but they do have balanced inputs.
What's the beef with damping factor? (This is non XPR-5 specific, but I thought very useful)
Another excellent write up, courtesy of KeithL:
The damping factor on all our amps is at least 500, and the differences between anything over about 100 are absolutely inaudible (and are difficult to even measure accurately in real-world situations).
If you look at the electrical models involved, the actual "delivered" damping factor is limited by the resistance of the speaker cables and the wire in the voice coils of your speakers. (A typical woofer has a DC resistance of about 2-3 ohms).
In the model, the internal resistance of the amplifier is ADDED TO the resistance of the speaker, then divided into the nominal resistance of the speaker. The internal resistance of an amplifier with a DF of 8 is 1 ohm; the internal resistance of an amp with a DF of 80 is 0.1 ohm, and that of an amp with a DF of 800 is 0.01 ohm.
So:
For an amp with the DF of 1, the *real* damping factor is 8/(8+3), which is about 0.7
For an amp with the DF of 8, the *real* damping factor is 8/(1+3), which is about 2
For an amp with the DF of 80, the *real* DF is 8/(.1+3), which is about 2.58
For an amp with the DF of 800, the *real* DF goes up to 8/(.01+3), which is 2.66
As you can see, going from a DF of 1 to a DF of 8 or 10 makes a huge difference (and those numbers are reasonable for tube amps), but anything past 100 or so doesn't make much difference at all (in fact, it gets really hard to measure over about 500, and the numbers may be different depending on what measurement method you use).
