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Post by nickwin on Dec 6, 2014 11:13:57 GMT -5
I could hear no difference switching from RCA to XLR connectors; both were dead quiet. I changed because I thought the XLR connectors were more secure (and sexy). My XLR's were from Emotiva, and I'm pleased with them. Sincerely /b Did you check the wiring on the Monoprice cables? They are not built correctly, they connect the shell to the ground pin which they even said is not proper. I just cut that connection on mine instead of try to return them. Wow really? I was just about to buy 5 of these for my XPA5. I've only heard good things about monoprice XLRs. I guess I will keep my options open. |
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Post by solarrdadd on Dec 6, 2014 11:27:25 GMT -5
Did you check the wiring on the Monoprice cables? They are not built correctly, they connect the shell to the ground pin which they even said is not proper. I just cut that connection on mine instead of try to return them. Wow really? I was just about to buy 5 of these for my XPA5. I've only heard good things about monoprice XLRs. I guess I will keep my options open. i've asked the poster to provide a link to show that monoprice actually admits this. i'm glad to hear you state you want to keep your options open, but, let's all not be quick to judge without seeing monoprice actually confirm this. |
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Post by hcsunshine90 on Dec 6, 2014 17:22:25 GMT -5
I HAVE two pairs of these monoprice XLR cables. I hope there's nothing wrong with them. what if one were to connect the shell to the ground pin in an XLR cable? what could the outcome be? loss in its noise reducing capabilities? damage to equipment?
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Post by Gary Cook on Dec 6, 2014 17:55:53 GMT -5
If we are talking about Monoprice XLR to RCA interconnects then not connecting the shield to the ground at the RCA end leaves the shielding incomplete. i.e. it's grounded at the XLR end but not at the RCA end. If there is a ground loop issue then cutting the shield at the RCA end sometimes (but not always) helps. If there is an external interference issue (EM or RF) then cutting the shield generally (but not always) makes it worse. So I don't see a right or wrong, it's depends on what we are trying to achieve with the XLA to RCA interconnect.
Cheers
Gary
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Post by Audiozealot on Dec 6, 2014 18:05:03 GMT -5
Wow really? I was just about to buy 5 of these for my XPA5. I've only heard good things about monoprice XLRs. I guess I will keep my options open. i've asked the poster to provide a link to show that monoprice actually admits this. i'm glad to hear you state you want to keep your options open, but, let's all not be quick to judge without seeing monoprice actually confirm this. Here is a portion of the chat I had with Monoprice:
TS - Joseph C: It's a shame the cable did not suit your needs. I can set up an RMA for return if you'd like.
ken: why did that last tech assure me that they have fixed this issue when they haven't?
TS - Joseph C: The cables should not be contacting the shell. As the the tech recommended the solution. Our Returns department could better assist you with getting the return with a returns label. Would it be possible to transfer at this time?
ken: i would like the cables to be fixed
ken: they are very nice cable otherwise
TS - Joseph C: I'll be logging the issue but unfortunately we do not have an ETA at this time.
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Post by hcsunshine90 on Dec 6, 2014 18:09:42 GMT -5
the above post does not indicate a problem with monoprice XLR cables to me. it shows that at least one person had this problem. the tech says that, "the cables should not be contacting the shell". he doesn't say monoprice BUILDS THEM that way on purpose.
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Post by Audiozealot on Dec 6, 2014 18:24:34 GMT -5
I HAVE two pairs of these monoprice XLR cables. I hope there's nothing wrong with them. what if one were to connect the shell to the ground pin in an XLR cable? what could the outcome be? loss in its noise reducing capabilities? damage to equipment? It should not hurt anything. It's just incorrect wiring. I was alerted to it in a review for the cables. The reviewer talked about the wiring and the fill material in the cable. Personally I think they are good cables. I like that the connectors are assembled with screws and the strain relief. I also like that they are 16 AWG. The shell is gold plated and started flaking off when I had them disassembled but since I was cutting that connection I didn't really care. |
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Post by Audiozealot on Dec 6, 2014 18:31:23 GMT -5
the above post does not indicate a problem with monoprice XLR cables to me. it shows that at least one person had this problem. the tech says that, "the cables should not be contacting the shell". he doesn't say monoprice BUILDS THEM that way on purpose. You will just have to trust me that this chat was with a Monoprice tech. If you don't then contact them yourself and ask. They don't build them this way on purpose It's probably a safe bet that they are assembled in China and there is a communication problem on the assembly instructions. |
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Post by moko on Dec 6, 2014 18:46:51 GMT -5
Moko, please do not claim that single ended and class AB are mutually exclusive. You are probably confusing facts about single and dual voltage rails, both of which can be designed for class AB. Furthermore many class of amplifiers have a diff amp at the input but it is not configured in the way you might think as the inverting input is used for negative feedback. The output of the front end of the diff amp is in class A to maintain linearity. This signal can be fed to an intermediate amplifier stage or directly to the output stage of the amplifier. Now this is where the push pull comes in as the positive half of the signal will cause the output devices connected to the +ve rail to conduct and vice versa. After a bit of a search I managed to find some text that explains the operation of a class B amp, so it is missing the biasing circuit of class AB but this is just an extension on the theory. You will notice that it operates in fully single ended mode with a dual rail power supply. www.uotechnology.edu.iq/dep-eee/lectures/3rd/Electronic/Analog%20electronic/5.pdfAs for cross connection of current mirrors in the input of a balanced amplifier, this is not the only way a balanced amplifier can be designed. As I stated above. yep, that article confirms what i mean. on page 25 : "15.5 CLASS B AMPLIFIER CIRCUITS
A number of circuit arrangements for obtaining class B operation are possible. We will consider the
advantages and disadvantages of a number of the more popular circuits this section. The input
signals to the amplifier could be a single signal, the circuit then providing two different output stages,
each operating for one-half the cycle. If the input is in the form of two opposite polarity signals, two
similar stages, could be used, each operating on the alternate cycle because of the input signal. One
means of obtaining polarity or phase inversion is using a transformer, the transformer-coupled
amplifier having been very popular for a long time.
Opposite polarity input, can easily be obtained using an op-amp having two opposite outputs or using
a few op-amp stages to obtain two opposite polarity signals, an opposite polarity operation can also
be achieved using a single input and complementary transistors (npn and pnp, or nMOS and
pMOS)."so in the real application, the input stage accepts single ended signal (referring to type of connection NOT how the gain stage works) then adding gain by using single ended class A design (reffering to how the gain stage works). but BEFORE the single ended signal can be fed to output stage which work in push pull mode, that single ended signal need to be split in opposite polarity (in-phase and inverted phase) using transformer or op-amp (like what emotiva did). the next page (page 26) gives clear picture of how push pull inputs should be :  now, if we already have 2 opposite polarity using xlr connector then it means we can by-pass that transformer or op-amp, right ? sorry i didn't explain it in a more specific way before. what i meant is : most class AB amps have single ended class A input stage (which add gain), but no output stage with class AB amp works in single ended mode because unlike class A which can operate in single ended or push pull mode, all class AB amps only work in push pull mode. this is another quote from that article from page 2 : "Class AB: An amplifier may be biased at a dc level above the zero base current level of class B and
above one-half the supply voltage level of class A; this bias condition is class AB. Class AB operation
still requires a push-pull connection to achieve a full output cycle, but the dc bias level is usually
closer to the zero base current level for better power efficiency, as described shortly. For class AB
operation, the output signal swing occurs between 1800 and 3600 and is neither class A nor class B
operation." |
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kdm
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Post by kdm on Dec 6, 2014 20:09:09 GMT -5
In a recent email, Emotiva told me that with a digital input, the unbalanced outs will have about 6db less dynamic range than the balance outputs, so 104db vs 110. They said distortion will be about the same. My initial thought was that the difference between 104db and 110db DR should be noticeable with high rez sources, so I was going to swap out my RCAs for XLRs when I got my XMC1, but it sounds like you guys are saying that difference will probably not be noticeable? My RCAs are 1.5 meters in length. This leads me to another question, if you can't hear the difference between 104db and 110db DNR, why do we even look at that specification? If you can't hear that difference its hard to imagine you could hear any difference between say 110db and 130db either. Is dynamic range a useless metric for most people once it gets beyond say 100db, which is well over what rebook cd can reproduce?Welcome to the world of audio sales: Lab measurements vs. human ability to discern the difference. It's real, and it permeates most of the industry. It always has, and it always will. I can still, vividly recall receiving "Stereophile" magazine (for over 2ys), back in the late 80's. A bunch of pretentious $%#@'s, pontificating on the worthiness of... "whatever"... product they were reviewing. I was still in my late 20's, and I bought-into a lot of their general BS. Nevertheless, I learned a lot from reading them monthly. The most important thing I learned a few years later, was that their flowery rhetoric had ZERO actual, meaning in real life (saying things like, "I felt elevation in the mid-to-high range", etc., lol. What load of crap. Snobbery rules this industry, and always at the expense of both, "informed" and "misinformed" persons. When you get to a certain level (IOW, not basic Big Store brand, lol,, etc....), the pissing contests begin, over, what is usually not detectable amongst most human beings. Back to the subject....mostly, lol. Read these links: www.roger-russell.com/wire/wire.htm#differenceswww.roger-russell.com/wire/wire.htm#thetruthAnd one of my favorites: www.roger-russell.com/wire/wire.htm#oxygenfreeAnd btw, what comprises a "balanced cable"? It's simple, two speaker wires.... and a ground. See where I'm going here? I can also still recall the period in the late 80's/early 90's, when I made several pairs of speakers (for myself, friends and family). The owner of a decades old audio shop, helped me choose and design crossovers. This guy was one of those "impatient geniuses". I asked him, "...but wouldn't 10 gauge wire be better to connect the caps/coils, etc..."? Without pause, he replied, "Sure, if you want to be sure you spend the most money that you possibly can to complete your project." He almost threw me out of his shop. He was that annoyed by that stupid question! Folks, don't trust anyone, except yourself, when it comes to audio. And sometimes....don't even trust yourself, lol, when a lot of money is involved  . Me? I just bought the XPR-5...and then the XPR-2...and WILL buy the XMC-1. Why? Because it's quality gear (from my own research). However, I'm merely updating some vintage gear that still sounds awesome. In other words, I'm largely doing it on the looks...and the specs of their design(s). Silly, you say? LOL, that's how most of us make purchases in life. Fact. I love the EMO line of gear. And yes, it delivers  |
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Post by Poodleluvr on Dec 6, 2014 20:56:36 GMT -5
"Snobbery rules this industry, and always at the expense of both, 'informed' and 'misinformed' persons.~kdm
I gotta share this...
Within my local area, we have a Best Buy store that includes a small Magnolia store that is located inside. This specific Magnolia store carries the lower end of B&W and Martin Login loudspeakers on the showroom floor...
Now, within a 2-hours drive from me in Tulsa is a Best Buy store that apparently has a much larger HT Magnolia store. I've never been to this BB or Magnolia store, but I am aware that this store carried the upper tier of B&W loudspeakers, like the 803D, 802D, 800D, and also sells electronics like Mcintosh, right on the showroom floor.
Well, I was interested in seeing and hearing the Polk LSIM series, including the LSIM 707 of which the MSRP for a pair is $4K plus tax, not exactly chump change...
So, I called the BB in Tulsa to see if their Magnolia store carried the upper end of Polk's loudspeakers, the LSIM series.
The first thing the Magnolia sales guy said to me on the phone was.... "This is the Magnolia Store"!
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kdm
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Post by kdm on Dec 6, 2014 21:50:35 GMT -5
Within my local area, we have a Best Buy store that includes a small Magnolia store that is located inside. This specific Magnolia store carries the lower end of B&W and Martin Login loudspeakers on the showroom floor... Now, within a 2-hours drive from me in Tulsa is a Best Buy store that apparently has a much larger HT Magnolia store. I've never been to this BB or Magnolia store, but I am aware that this store carried the upper tier of B&W loudspeakers, like the 803D, 802D, 800D, and also sells electronics like Mcintosh, right on the showroom floor. Well, I was interested in seeing and hearing the Polk LSIM series, including the LSIM 707 of which the MSRP for a pair is $4K plus tax, not exactly chump change... So, I called the BB in Tulsa to see if their Magnolia store carried the upper end of Polk's loudspeakers, the LSIM series. The first thing the Magnolia sales guy said to me on the phone was.... "This is the Magnolia Store"! Were you actually, surprised? Guys, this is a fact of life: The sales of most A/V equipment is based on "sexiness", and less on specs. Personal example: because I made speakers at one period of my life, I had an introspect, better than the avg. guy/buyer, OK? BIC America, offers one of the best "values" on the freaking market! Their specs are outstanding, an their performance is incredible, for the price. My only misgivings, are that i can make them "cave" ......at extraordinary listening levels....which, most people don't drive to. Check them out: www.bicamerica.com/showpage.php?brand=2&type=6&spkrID=97No, I'm not a shill for the company. Their speakers simply, rock! You cannot beat their performance...for the price. OTOH, if you're like me, and a "full cranker", they can't deal. Just being honest. |
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Post by garbulky on Dec 6, 2014 22:30:42 GMT -5
I just used monoprice XLR's to record off stereo microphones with phantom power not an hour ago. They worked GREAT. No noise or hum. Thick looking cable. I reccomend them.
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Post by richardrc on Dec 7, 2014 0:11:24 GMT -5
Hi Moko, what you have highlighted could be done with two identical output devices but is not for reasons of gain and output resistance mismatching as well as time alignment in the final output stage. So what is used is shown in figure 15.16, which is a complementary pair. The input is single ended and the output is single ended, no need to invert one of the signals. Very frequently differential amps are used in the input stage and it could be designed to accept a difference signal but generally this is not the case. I believe Emotiva amp front ends do not accept a difference signal and there would be no way to inject one further down the signal path as you have suggested. For interest here is a design that utilises 4 diff amps, it is still single ended. link |
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Post by Porscheguy on Dec 7, 2014 8:36:58 GMT -5
According to the Emotiva Products Page the XMC-1 using Balanced input to Balanced output has a SNR od 123db. In Unbalanced output to Unbalanced input it has a measured SNR of 114db. Can any of you speak to the differences, if any, that you hear when switching from Unbalanced connection to Balanced connections with the XMC-1. For instance, are you using the XPA-1 or XPA-1L with the XMC-1 now vs any other Emotiva amp or an unbalance amp from another manufacturer? Forgive me, but does it matter which whether its 123db or 114db? Both put the noise floor well below what humans can hear..... To borrow from DYohn: Inaudible is inaudible and you don't get extra brownie points for making it twice as inaudible as another solution. |
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Post by kdm on Dec 7, 2014 9:23:28 GMT -5
This clip says it all: (warning - the F word is used once, so be careful when watching/sharing)
Extrapolate, sit back in your chair....and realize.
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Post by AudioHTIT on Dec 7, 2014 12:23:23 GMT -5
I agree that once a spec has reach a certain point that improving the specification alone may not yeild audible benefits (S/N 123 vs 114). The assumption people are making is that the designer set out to create a lower noise device; it's possible though that the improved spec is the result of an overall better design, shorter signal paths, higher parts quality, or some other design aspect. The circuit with the 123 dB may sound better because of a better design and implementation, the improved S/N just a by-product.
On the other hand the product with the improved spec may even sound worse, as bad design practices may have been used to achieve the impressive number. This occurred in the 70's when some designers used copius amounts of feedback to achieve low distortion numbers; designers like Nelson Pass looked at the overal design to reduce distortion without resorting to excessive feedback.
My point is that while the difference between 114 and 123 dB S/N may not be audible it doesn't mean that the two circuits (or devices) might not sound different, and that the one with the 123 dB S/N may sound better (or worse), one number alone doesn't measure a device.
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Post by AudioHTIT on Dec 7, 2014 13:25:23 GMT -5
I just used monoprice XLR's to record off stereo microphones with phantom power not an hour ago. They worked GREAT. No noise or hum. Thick looking cable. I reccomend them. I agree the Monoprice XLR cables work fine for occasional use like you suggest, I have a collection for random uses, but I'm not crazy about the connectors or the thick, low flex cable. If I were buying a set of 7 to use between an XMC-1 and XPA-7 (for example), I'd use a higher quality cable with better flexibility and nicer connectors - like BlueJeans. I'm not saying they'd sound better, but they're easier to route and the connectors go in and out more smoothly. If your budget allows, spending another $100 or so after spending a few thousand on components can make hookup and maintenance a lot more pleasant. |
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Post by moko on Dec 7, 2014 18:41:28 GMT -5
Hi Moko, what you have highlighted could be done with two identical output devices but is not for reasons of gain and output resistance mismatching as well as time alignment in the final output stage. So what is used is shown in figure 15.16, which is a complementary pair. The input is single ended and the output is single ended, no need to invert one of the signals. Very frequently differential amps are used in the input stage and it could be designed to accept a difference signal but generally this is not the case. I believe Emotiva amp front ends do not accept a difference signal and there would be no way to inject one further down the signal path as you have suggested. For interest here is a design that utilises 4 diff amps, it is still single ended. linktrue, but the result won't be balanced and it's still called push pull amp. single ended amp doesn't need complementary pair (npn and pnp) because 1 output device handle full sine wave (positif and negative swing). the balanced configuration is meant for supressing even order harmonics and reducing the noise (known as common-mode rejection ratio). now, when emotiva said it's dual or quad differential i believe they are telling the truth : it means they are dual/quad differential from input stage until summed at speaker outputs. if you look at the top view of xpa-1, you will see that there's an op-amp between rca jack input and input stage of the amp. i believe this op-amp is a phase splitter for single ended signal. are you saying that xpa-1 is not fully balanced ? |
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Post by richardrc on Dec 7, 2014 22:40:48 GMT -5
A push pull complementary output pair (npn pnp) is single ended. A single npn or pnp device with 360 deg conduction angle is biased in class A.
The XPA-1 is comprised of two identical single ended amplifiers and yes I agree the opamp is most likely for inverting the input signal to feed one of the single ended amplifiers in the XPA-1.
The dual/quad differential or cross connected current mirrors is meaningless to 95% of people. Lots of audio speak is pure BS eg RMS for power as there is no such thing or slew rates of 1000V/us All used to sell, which is why I will never buy into the expensive interconnect debate. (Oh no I hope I havne't opened another can of worms!!!!) The proof is in the sound and lets face it, most of the guys and gals or can afforded it have BIG hearing deficiencies. I know my own hearing tops out at around 15.5kHz and the only reason I know my speakers are still making sound above this frequency (apart from using a microphone) is becasue my kids tell me! Although I might have better audible acuity, having learned to play an instrument.
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