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Post by UT-Driven on Mar 11, 2013 15:02:59 GMT -5
Hello One and all, ---snip---- To stat let me explain what S/N is. All amplifiers have a residual amount of noise that they produce when running. In this case the test signal was set to 1 Watt and the residual noise of the amp at that level was -86db down from the test signal. This will give you an idea of how quiet the amp is in relation to the signal it is producing. Now lets plug this into a real world scenario. Let us just say that your speakers will produce 89db of sound with a 1 watt signal going into them. Given the noise floor of the amp being 86 this would mean the residual noise floor of the amp is now right at 3db. ---snip--- I hope this helps and thanks again to everyone for all the interest. Lonnie Thanks for the explanation Lonnie. It sounds like I was on the right track regarding S/N ratio. It's one of the most exciting amplifiers I see coming out now. Doug
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Post by UT-Driven on Mar 11, 2013 15:06:13 GMT -5
I know I'm newbie here but: I think the XPA-1L has the potential to be quite a bit more than half an XPA-1 although I understand the analogy, the POV and appreciate the background story. A true 35 watt Class A amp at this price point is unreal, well not really unreal because you guys have made it a reality. Thank you. I'm guilty of over analyzing the specs a bit but what else is a boy to do until the toys arrive? I've heard the Parasound JC1 monoblocks and they are the best amps I've ever heard. The owner suggested I check out the XPA-1s as being the next best thing at 1/4 of the price. While the XPA-1L is not in that monster class there are definite similarities in design with the JC1. One question, I generally leave my pre-amps and amps on all of the time and plan on doing the same with the XPA-1Ls except switching them to class A/B mode when done listening. Will this help keep the capacitors charged? The reason I ask is that I've read(Pass Labs) that Class A amps benefit from a warm up period more than other topologies. I would be very interested to hear your thoughts on these when you get them. So please let me know your thoughts and opinions. All of our amps are designed to be left on 24/7 so it won't be an issue and will keep the caps charged. Switching them to Class A/B when not being used is probably a good idea at least in regards to your electric bill. ;D Not that these should cause a night and day difference, but when running in Class A mode they will use up the same amount of energy whether or not they are playing or not. So by switching them to Class A/B the current draw at idle will go down. Enjoy. Lonnie Curious, could they have been designed to go into Class A/B when no signal as present? Something for a future revision, if applicable? Doug
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Post by milt99 on Mar 11, 2013 15:08:46 GMT -5
Or just trying to show an equivalent spec between the amps. As I stated previously, I've heard a pair of JC1 on multiple occasions and they are fantastic amps and really, outside of the Emotiva Universe, competitively priced.
They are about 30lbs heavier than the XPA-1L with a 1900 va transformer vs the 450 va in the Emotiva etc., etc. I'm speculating that if Emotiva built an amp that closely emulated the JC1, it would not fit in with their current product\price structure.
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Post by milt99 on Mar 11, 2013 15:12:11 GMT -5
Maybe but a switch is a simple, effective solution. The Halo JC1 uses the same solution only it's on the back of the amp.
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Post by Jim on Mar 11, 2013 15:15:21 GMT -5
I think Parasound (JC1) is only via dealers anyway, so figure 50% of the retail price is markup.
I think that the 1L fits plenty of criteria. Affordable, lots of class A power, nice form factor. Still plenty usable beyond the 30W of class A (on the fly, no less).
It looks like the JC1 isn;t that different, just looks like they're playing the numbers game hard with a huge transformer and lots of capacitance. And junk like "Vampire Direct gold-plated OFC RCA input " Parasound specifying things like SNR without specifying 1W, full range, idle, anything is useless.
Can we see some Audio Precision data from Parasound? hahaha.... no. (I'm not putting Parasound down, I just don't like marketing junk). I'm sure they're good amps.
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Post by Dark Ranger on Mar 11, 2013 15:31:15 GMT -5
Maybe but a switch is a simple, effective solution. The Halo JC1 uses the same solution only it's on the back of the amp. I see a bias level switch, but not a Class A/AB switch. I've always had a secret crush on the Halo JC1 amp, both for aesthetics and raw performance. However, it's out of my price range and there's no way I can justify saving for one at that price. It's also quite large for my tastes. Emotiva has made a dream of mine come true: a highly-affordable mono-block in a low-profile chassis with satisfactory power handling and plenty of Class A performance. Oh, and I almost forgot the most important thing: incredible value. Will the XPA-1L sound identical the JC1? Probably not, but that's OK. Even if I can get 70-80% of the performance/sound quality of the JC 1, I'm thrilled. Best part? I saved $4,600.
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Deleted
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Post by Deleted on Mar 11, 2013 15:41:47 GMT -5
From a Stereophile test: " The JC 1's unweighted, wideband signal/noise ratio (ref. 1W into 8 ohms) was good at 73.3dB, this improving to 87.8dB when the figure was A-weighted." (don't know if wideband makes any difference or if the XPA-1L is the same) 25/400/800 watts, 7.625" high Current price on the JC! at Audio Advisor, $4500. So, what you're saying is that we should spend 6x more so that we can get that inaudible 1.8db in SNR at 1W. Right? ;D ;D I'm fond of specs, but they don't tell you everything, that's for sure. My main reason for the post was that some folks seemed to feel the XPA-1L SN spec of 86dB's A-weighted was on the low side. Parasound shows a SN spec of 120dB's, IHF A-weighted. That is using a different standard and the test showed 87.8dB's or an increase of 1.8dB's which is a very slight difference, like Jim pointed out. The other brief info gives a good indication of the relative value of the XPA-1L.
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Post by Jim on Mar 11, 2013 15:48:31 GMT -5
I think the confusing part, is that the Stereophile tested wideband SNR is at 1W, whereas the Parasound spec is unclear.
On the Parasound, the claimed 120db could be at any wattage. (Right??)
The 1L is >110db at rated wattage.
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KeithL
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Post by KeithL on Mar 11, 2013 15:58:55 GMT -5
To be totally honest, there are two things that should be clarified here.... First, you may or may not hear a difference between Class A and Class A/B. Like many other subtle differences, that will probably depend on the rest of your system, how good your ears are, and especially the quality of the content you are listening to (you're only going to hear a difference with a very good quality recording). All we can say for sure is that SOME people, on SOME systems, with SOME musical source material hear a clear difference - and those that do virtually always prefer the Class A amplifier. Now, you need to understand what "transition point" means. Let's assume you're listening to music at a pretty loud level... with typical speakers, that might well work out to 5 to 10 watts average, and 100 to 200 watts peak. Now, if you've got the switch in the Class A/B position, you're listening in Class A for only the first few watts, and all the rest is in Class A/B. However, if you've got the switch in the Class A position, you're listening in Class A for the first 35 watts (which is most of what you're listening to), and only the occasional peak is going into Class A/B. Compare this to a "35 watt pure Class A" amplifier: on that, the first 35 watts would be in Class A, but the peaks would be clipped off (it would sound good but you wouldn't be able to play it at all loud). Now compare it to a "normal" "250 watt Class A/B" amplifier: on that, everything would be in Class A/B (that's what you have with the XPA-1L switch in the Class A/B position). As you can see, the XPA-1L is superior to both. So I am new at this. If you are listening to a class A amp in class A mode and it transitions to class A/B do you hear a difference in sound quality? If not than is class A just hype? Don't mean any offense, just curious
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Deleted
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Post by Deleted on Mar 11, 2013 16:00:49 GMT -5
I'm speculating that if Emotiva built an amp that closely emulated the JC1, it would not fit in with their current product\price structure. The XPA-1 weighs in at 76 lbs for a full size box. If Emotiva decided to make an amp with almost identical specs to the JC1 I speculate that it would run about 68-72lbs and cost about $1199 list. Emotiva's current product/price structure is based on a factory direct to buyer mark up as it is for all of their amps. Parasound is based on the customary retail high end store several levels mark up (plus commisisons) from the factory to the end user. The end result is that Parasound amps run about 3-4 times the price of comparable Emo amps to the end user. I doubt if anyone here denies that the JC1 is a very fine amp. There obviously is no argument that the Emotiva amps are much prettier! ;D PS: Sorry Jim, my mistake. That high SN ratio is most likely at full output. The a-weighted SN at 1W is very close for both amps.
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Post by Boomzilla on Mar 11, 2013 17:23:51 GMT -5
WHOOOMP - DEY IT IS!
Just got the e-mail - IT'S OUT!
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Post by milt99 on Mar 11, 2013 17:47:08 GMT -5
That's exactly what the switch is. It sets how many watts the amp biases into Class A. On the low setting, the first 10 watts are Class A, on high the first 25-28 watts depending on what specs\tests you read.
Emotiva hasn't specifically said but I'm assuming the switch on the XPA-1L will do like 1 watt on the A\B setting which effectively sets how the amp is biased. Along with the other postings, when I read\listened about the XPA-1L it seemed obvious that I would be running in Class A while listening and switch to A/B for idle.
You really need dedicated lines to run the JC1s. I know some will disagree but I would be compelled to run at least 2 15amp circuits if I had the JC1s and if you're going to go to the trouble of running 15 amp lines, 20 ampers aren't that much more. If I was going to buy the XPA-1s I would run dedicated lines as well.
Actually if you had bought 2 you would've saved $9200-$1400= $7800. So really you should've bought 2. Remember, math doesn't lie ;D
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Post by milt99 on Mar 11, 2013 18:04:12 GMT -5
KeithL There are other high biased Class A amps that switch from A to A/B on the fly. Pass XA.5 amps for one. How loud your system plays or more accurately how much headroom your systems needs also depends on the music you're playing, your speakers sensitivity and of course how much you crank the volume. That is what I'm really, really curious to find out. My system sounds just great right now on low volume and on some material at higher volume. But the current loaner just doesn't do it at higher volume on certain material. Things get distorted and congested. That's where my friend's system with the JC1s absolutely shines. It also sounds beautiful at low volume as well. I want that!
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Post by rouslanbel on Mar 11, 2013 18:05:13 GMT -5
To be totally honest, there are two things that should be clarified here.... First, you may or may not hear a difference between Class A and Class A/B. Like many other subtle differences, that will probably depend on the rest of your system, how good your ears are, and especially the quality of the content you are listening to (you're only going to hear a difference with a very good quality recording). All we can say for sure is that SOME people, on SOME systems, with SOME musical source material hear a clear difference - and those that do virtually always prefer the Class A amplifier. Now, you need to understand what "transition point" means. Let's assume you're listening to music at a pretty loud level... with typical speakers, that might well work out to 5 to 10 watts average, and 100 to 200 watts peak. Now, if you've got the switch in the Class A/B position, you're listening in Class A for only the first few watts, and all the rest is in Class A/B. However, if you've got the switch in the Class A position, you're listening in Class A for the first 35 watts (which is most of what you're listening to), and only the occasional peak is going into Class A/B. Compare this to a "35 watt pure Class A" amplifier: on that, the first 35 watts would be in Class A, but the peaks would be clipped off (it would sound good but you wouldn't be able to play it at all loud). Now compare it to a "normal" "250 watt Class A/B" amplifier: on that, everything would be in Class A/B (that's what you have with the XPA-1L switch in the Class A/B position). As you can see, the XPA-1L is superior to both. So I am new at this. If you are listening to a class A amp in class A mode and it transitions to class A/B do you hear a difference in sound quality? If not than is class A just hype? Don't mean any offense, just curious Hi Keith (or Dan), I am currently using XPA-2 which drives Mirage OMD-15 speakers [Oppo 105 as a source]. Mostly listening to classical music at medium volume. Would XPA-1L be a good upgrade for me or XPA-1 could be a better upgrade path in my case?
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Post by Dark Ranger on Mar 11, 2013 18:17:45 GMT -5
That's exactly what the switch is. It sets how many watts the amp biases into Class A. On the low setting, the first 10 watts are Class A, on high the first 25-28 watts depending on what specs\tests you read. Ah, I see. I believe I misunderstood you based a knowledge gap regarding biasing and Class A. Your explanation makes perfect sense. Emotiva hasn't specifically said but I'm assuming the switch on the XPA-1L will do like 1 watt on the A\B setting which effectively sets how the amp is biased. Along with the other postings, when I read\listened about the XPA-1L it seemed obvious that I would be running in Class A while listening and switch to A/B for idle. Good point and this would be an interesting tidbit to know. I've read that most of the Emotiva amps run in Class A for less than 1 watt, and then do A/B for the rest. However, perhaps the 1L is different in this regard since it's designed to handle more Class A power. If 35 watts would be the high bias setting, perhaps it would do something like 10 watts (similar to the XPA-1) in A/B mode. Or maybe it's just <1 watt like the other Emo amps. My original intention was to switch to Class A/B for idle specifically for power conservation, but I'm also not opposed to just turning off the amp when not needed. I'll see how much it will impact the electric bill. My other concern relates to the duty cycle of the front panel selector switch. I don't want to cause undue wear if the switch won't stand up over time. Actually if you had bought 2 you would've saved $9200-$1400= $7800. So really you should've bought 2. Remember, math doesn't lie ;D I haven't checked prices recently, but I remember the JC1 could be had for $3,000 each at one point. So at $6,000 for a pair, versus $1,400 for a pair of 1L, that's a savings of $4,600 to me that I can use to spend on, uh, speaker cable!!! I do get the joke.
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Post by milt99 on Mar 11, 2013 18:51:55 GMT -5
Sorry Ranger, I exaggerated, the JC1s are $4500 per, not $4600. One thing to consider re: switching between A-A/B and power down. I'm a believer in leaving gear on. It may be out-moded now but power cycling imo, is harder on equipment than running at idle plus my system sounds better to me when it has a chance to warm up. Heat is the enemy of electronic gear and as long as it idles warm it's ok. Most if not all makers of Class A gear whether they switch to A/B or not say that the amp will sound better 20-30 minutes after power up. My old Rappaport was designed NOT to be powered off but it got so damn hot that I did power it down as I worried about the huge capacitors and heat. I'm going to believe them and leave the XPA-1L on but just switch to A/B mode when not listening. The only thing I can say is try it for yourself and see if you notice any difference.
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Post by Jim on Mar 11, 2013 19:48:25 GMT -5
However, if you've got the switch in the Class A position, you're listening in Class A for the first 35 watts (which is most of what you're listening to), and only the occasional peak is going into Class A/B. That's interesting. I misunderstood the modes. I thought that when it went to class A/B that wasn't just for peaks. I thought that when you exceeded the 35W mark, the amp flipped into A/B and turned back to A when you turned the volume down (For example). I was thinking a delay in the matter of seconds, or something. Never occurred to me that it if you exceeded that threshold with peaks only, 99% could be class A, and those 1% (or 2 or 5 or whatever %) peaks would only be A/B. I don't know if I can hear class A vs A/B, but I'm interested, regardless.
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Post by Jim on Mar 11, 2013 19:51:58 GMT -5
Hi Keith (or Dan), I am currently using XPA-2 which drives Mirage OMD-15 speakers [Oppo 105 as a source]. Mostly listening to classical music at medium volume. Would XPA-1L be a good upgrade for me or XPA-1 could be a better upgrade path in my case? I'm not Keith or Dan, but looking at the specs for the OMD-15, I think that the XPA-1L would match extremely well. It looks like Mirage actually gives realistic wattage numbers too. The XPA-1s wouldn't hurt, but you wouldn't have much use for the extra power.
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Post by Jim on Mar 11, 2013 19:56:25 GMT -5
PS: Sorry Jim, my mistake. That high SN ratio is most likely at full output. The a-weighted SN at 1W is very close for both amps. No need to apologize. I realize I've been blathering about the JC1, I'm not sure how much sense I've made. I feel the JC1 has it's place, but it's definitely for a different market. One thing that I've always liked about Emotiva amps is the transparency in the specs and the test results. The fact that Dan and Lonnie have talked about the SNR numbers in a real manner -- rather than blowing smoke is pretty significant too. We can blab on and on about specs and we get Keith/Lonnie/Dan's comments - including some good ones informing us about how we're making a big deal about some not very important spec.
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Post by milt99 on Mar 11, 2013 20:21:49 GMT -5
What I'm waiting for is a FEDEX shipping notice and tracking number.
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