6" This is false, your either hearing things or your biased toward your own retail preamp product.
In
many cd players or dacs I've seen the balanced output is just an added
opamp changing the "real' single ended circuit to balanced. Same goes
with the input of many poweramps, which btw are single ended output to
the speakers.
The only time balanced is better from source to to
pre, or pre to power is for noise cancellation with interconnect over
5mts>
I certainly do hear things :) George, one thing you will see me harping about a lot is that a lot of high end manufacturers don't support the balanced standard, or for that matter don't seem to know that such a standard exists. You seem to be one of them. The standard is defined in the AES File 48. Here are the basic aspects of balanced line operation, going back to the 1950s: 1) the operation is low impedance, in particular the source 2) the signal occurs with respect to its opposite, rather than ground (IOW the non-inverted and inverted phases); ground is ignored and is only used for shielding- no signal currents are in the ground connection! 3) pin 1 is ground, pins 2 and 3 carry the signal (neither is 'hot' or 'cold'). In the US, pin 2 is non-inverting. If the device used does not support the standard, you may not get all the advantages that balanced operation offers. Off the top of my head, this is one reason I don't recommend passive volume control systems, since I can't think of a way they can be set up to support the standard; see points 1 and 2 above (a TVC could do it, but I've yet to see a TVC that had all the loading issues solved and didn't color the sound). As a result, with a passive you still have to audition the cable in the resulting system, and the whole point of balanced line is that you **don't** have to audition the cable, because its simply going to work right and sound right, 6" or 30 feet no difference. Now to address some other misunderstandings you have in your statement above, many DACs fly in the face of your comments about their internal construction, for example MSB, where the internal construction often includes more than one DAC, running out of phase. But more to the point, the reason to go balanced and whether you can do it properly has nothing to do with the internal circuit and has everything to do with how that circuit talks to the outside world. An example is the old Ampex 351 tape machine, which uses input and output transformers to do that job. Audio Note made a DAC that operated in a similar fashion. IOW if you have an entirely single-ended circuit which drives an interface that properly supports the standard, the result is that you don't have problems with the interconnect cables. Although our circuits are entirely internally balanced differential, that isn't needed if the circuit simply has the right interface (there are benefits from balanced differential operation of the circuit, but that's another conversation). From your post, it seems you don't understand what that's about. I've always thought that audiophiles would jump at the opportunity balanced represents. I've heard interconnect cables make a night and day improvement in a system; many audiophiles have. When you run balanced, the cables no longer editorialize (and you get lower noise). I've seen a set of $200 30 foot cables beat out a set of 20 foot cables that were $1000/ foot, so this can be pretty significant. Your comment about amplifiers is also false- I don't have to go very far to prove that; the amps we make are balanced all the way to the loudspeakers and I can name quite a few more- the GAS, BAT, any amplifier that is bridged, any tube amp running zero feedback. |
And as far as balanced sounding better than single ended this is a
Furphy, the only time this may happen is if the interconnects are very
long (over 5mts> 10mts)
This statement is false- balanced lines offer less coloration even if they are only 6" long. This is way you can run longer lengths with them, since they have far less coloration. Just today I installed balanced cables in a system that were only 1/2 a meter and the improvement was instantly audible. |
No. Balanced definitely helps. I find I get better bass going from single ended to balanced when running active preamps as well.
|
The ARIA imparted more energy in the upper bass region, which seemed to
smoothen (i.e.: make more flat) this area compared to the SOtM
DAC-direct connection, and moreover spatiality and/or the sense
dimensionality was more pronounced/convincing, which was especially
apparent during live applause sequences that seemed to emanate from a
plane just behind the speakers with striking realism - quite impressive.
The uptick in upper bass energy also made voices come through with a
bit more solidity.
The most common problem with operating a passive control is the loss of bass impact; in this passage you are confirming it. What I don't get is why you stopped with the Aria. There are a lot of preamps out there, and they really vary! IMO/IME it is a statement about how bad many of them are that a passive system can keep up with them. Getting a sub adjusted correctly is always a tricky bit- and I know David Belles well enough to know that his electronics are really flat- so the bass you are referring to above was not being enhance by his preamp. It some other interaction, and setting up the sub to compensate is creating a synergy. IME again, synergies are usually a situation where one weakness is played against another, resulting in something that *seems* better than either on their own. An alternative is that if you worked with stuff that stood on their strengths rather than their weaknesses, you create something that is even better. I would try a variety of preamps and see if you can do better that the Aria, and be willing to readjust the sub in that light (since you were willing to do that to compensate for the usual loss of bass otherwise...). You might also look into tube preamps; IMO they offer more detail than solid state. |
I'm not trolling, you can stalk me all you like, you "try" to present
facts your way, and I'll do them my way, with whoever/whatever proof I
have. George, sorry, you're not fooling me. Endlessly spouting the same thing over and over, especially when you know you are leaving out important facts, is one way trolling is defined! The result of trolling is that someone has to correct your misrepresentation- and then we go on and on, around and around. That's classic trolling. If you are such an admirer of Nelson then don't make it as if he is saying something he isn't. That seems disrespectful to me at the very least. |
@georgehifi When you continue to cherry pick comments from an article that clearly favors active circuitry its disingenuous to say the least. Are you trying to make Nelson a liar??
Repeating it all over and over does not make it right- it just makes it trolling.
|
all I could find on the Baxandall was math and schematics. What good is that? Pretty good if you want one and no-one sells one. You just have to find someone to make it. We can do stuff like that, but as a one-off it might not look at that great. It has a lot more VC control, in addition to a significantly reduced
noise floor and a much bigger sound stage. I was surprised by how much
bass was missing from the 105 direct to amps.
Yup. The difference between passive and active right there. |
Imagine that with LDRs You can get more linear response with a Baxandall control FWIW. |
Can we really expect a simple pre amp to improve on the mastering
engineers ear and gear? If so just put a bunch of your favorite preamps
in series and the sound would just keep getting better! Improve on it no- maintain neutrality yes. If you were instead to put a bunch of your favorite passive volume controls in series, the result would not be pretty. Nor would putting a bunch of active preamps in series. The idea in high end audio is to do the least damage to the signal while getting it from the source to the speakers. The simple fact is that a passive is too simple to do the job. The reasons why have been explained several times in this thread. |
Did I miss anything? @phomchick I assume the question is rhetorical, since you and I had an exchange earlier on this thread that relates to your post. To answer it directly though, if in the context of your last post, then 'yes' (BTW, did you try that test I suggested?). The reason to use an active line stage is to reduce coloration. The coloration can be caused by the cables and the math that derives therefrom (bandwidth limitations, increased output impedance of the source and thus the impedance driving the amplifier). Gain may not be needed, but buffering the input and output of the volume control so that the source and amp see a constant impedance is. In this way the setting of the volume control may not also act like a sort of tone control. One way an active line section is handy, especially if a digital source is involved, is how the volume control is used. The technique is to run the volume control of the digital source all the way up, and then use the volume control on the active line section. Especially if the volume control is digital, this has the effect of increasing resolution. BTW I'm pretty sure that the Oppo uses an analog volume system, but it is chip based and chip based remote volume systems can have their own set of issues. But IMO they are better than using a digital control. |
I think your the one that needs to lay off the false claims about
passives with blanket statements about their ability to drive ect ect.
Every time they are bought up, your on it to protect active preamps.
Here
is a person you should kneel to as he is one who makes active preamps
for a reason which I’ve outlined, yet he is man enough to tell what it
is about passives that’s the real deal. You just deny them as a whole,
just like the "detriments" of a certain autoformer.
I have math to back me up on all my claims. I have also been careful to point out that passives can work fine if one is careful in the setup. You are protesting just a little bit too loudly... I've got nothing bad to say about Nelson- he is a brilliant designer and I often point out in my posts that he makes some of the best solid state gear out there. Its my opinion that its a lot harder to build a solid state preamp that's going to sound right; Nelson does a pretty good job but maybe his passives are showing up some problems with his active preamps (if not, you are the expert on his quotes- you figure it out). Our customers seem to think our gear sounds better (probably why they are our customers instead of someone else's...), but we have a lot of customers that run Nelson's amps with our preamps: we have customers in common. And we are on good terms with the folks at Pass Labs. Saying that everyone that sells active preamps is just in it for the money and somehow that someone selling passives isn't is as hypocritical as it gets. IOW, you just attack active preamps because you want to sell more. Its not because your gear works any better! So how does that feel George? That's the sort of crap that you lay at other's doors. The simple fact is, I have no idea what your motivation is (just as you have no idea of my motivations), I wrote that accusation so you can see how it feels. I've heard the Lightspeed and it works fine in the right circumstances. I keep trying to be reasonable with you but you keep going off like a five dollar pistol. Perhaps you can tone it down a little- I can easily demonstrate situations where an active works with less coloration than a passive, and I can demonstrate situations where a passive offers no coloration as well. Its all in the setup. I **know** you know that. Lay off the crap. |
This is picking hairs and scare mongering, and just selecting a worst case scenario.
90% of amps are 33kohm input impedance or higher.
The impedance of the amps is not the issue. The impedance of a 10K control is. Per your post prior to mine: It doesn't matter one iota where the volume control is positioned here,
these figures have a perfect impedance match regardless of volume
position. As do 90% of sources and amps out there when mated to ***10kohm***
passive volume controls.
*** emphasis added. With a 10K post, we can always count on the total load being less than 10K. At full volume it will be 7.5K, increasing to 10K at minimum volume in the example above. Not to put too fine a point on it George, but your constant and false claims that active preamp manufacturers are only in it for the money is disingenuous at the very least; your remonstrations come off as hypocritical! So how about you lay off? Others and I could have easily called you on it years ago; its become tiresome. |
It doesn't matter one iota where the volume control is positioned here,
these figures have a perfect impedance match regardless of volume
position. As do 90% of sources and amps out there when mated to 10kohm
passive volume controls. This statement is false. Its not wise to assume that 90% of all sources can drive a 10K load. The position of the control does affect the sound in many cases (although most people don't get to find this out because if a digital source is used, the output will likely be clipping the amp). So an audition with something like a tuner that makes less voltage and so won't clip the amp will reveal the issue. Audition is the bottom line- if everything is set up correctly, a passive will work fine. So the only reason for a lack of bass in this case (if correct) is a
coupling cap that's too small, and that 100ohms source output impedance
is rising at low frequencies which "would" roll off the bass. This conclusion is based on a false assumption, and so is also false. Its highly unlikely that so many sources would have a coupling cap at the output that is too small. |
The only reason for lack of bass, which would also rob warmth, is if the
source’s output is "capacitor coupled", and that capacitor is too
small.
It’s a simple fix to double the uF (microfarad) of the
capacitor and at the same time use a better "quality" one, as most skimp
here with average quality industry ones.
Myself, all my
sources, and everything else is direct coupled, which has the best bass,
and no "sound of a capacitor" in the signal path. I'm sure the source's coupling cap is large enough (I agree that a direct-coupled output can sound better; we use a direct coupled output in our tube preamps). Output coupling caps are extremely common with many sources. If proper design is applied, a relatively inexpensive electrolytic cap can have performance similar to high quality film capacitor (I realize this statement might be controversial to some; please note the caveat 'proper design'). The problem is that putting a series resistance in the circuit (which happens by turning down the volume in a passive control) effectively raises the output impedance. In turn, this raised impedance must drive a lower resistance (the shunt of the volume control to ground, which is in parallel with the input impedance of the amplifier). When this is done, the output impedance at 20Hz (which is usually higher than the output impedance at 1KHz) is raised also. The combined aspects of the control can thus make the source less able to make bass at the input of the amplifier. This is easily heard. Installing a larger coupling cap is often impractical! A larger cap might also induce low frequency instability in the source, depending on its design. It will certainly introduce additional coloration, due to the additional inductance since capacitors are wound in layers, and you need more layers to create a larger capacitance. Reducing the value of the control can reduce the timing constant problem, but can also pose a problem for some sources. The bottom line is that you have to try it and see, while also comparing to a competent active preamp. |
Although it is very good it lacks in bass and warmth for me. I’m using the audible Illusions again.
That is the most common experience we hear about passives. |
Maximum Gain 10 dB
Freq. Response +0, -1 dB @ 10 Hz and 100 kHz
Distortion < .1 % THD Hm. We can do that with 1Hz to 400Khz, distortion at 0.01%. And that's with no feedback. And all tube, balanced. |
An interesting circuit- the output of the follower drives the top of the control; its output (running wide open gain) is thus mixed with the incoming signal.
While Nelson's comments are essentially true, they are not the whole story by any means. One weakness of this circuit is the extremely low impedance the source must drive, which in this case is less than 2000 ohms if the schematic George linked is correct. Most sources can't drive such a load at all.
|
George excerpted a quote from Nelson Pass's website. It makes it look like Nelson had a certain position on the subject, but if you read what follows, you might see that such is not the case. Here is that further text (I've included the end of the text that George quoted earlier):
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”,
is a commonly heard refrain (really - I’m being serious here!). Maybe
they are reacting psychologically to the need to turn the volume control
up compared to an active preamp."
I suppose if I had to floor the accelerator to drive 55 mph, maybe I’d
think the life was being sucked out of my driving. Then again, maybe I
like 55. Nice and safe, good gas mileage…
Is impedance matching an issue? Passive volume controls do have to make
a trade-off between input impedance and output impedance. If the input
impedance is high, making the input to the volume control easy for the
source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And
vice versa: If your amplifier prefers low source impedance, then your
signal source might have to look at low impedance in the volume control.
This suggests the possibility of using a high quality buffer in
conjunction with a volume control. A buffer is still an active circuit
using tubes or transistors, but it has no voltage gain – it only interposes itself to
make a low impedance into a high impedance, or vice versa.
If you put a buffer in front of a volume control, the control’s low
impedance looks like high impedance. If you put a buffer after a volume
control, it makes the output impedance much lower. You can put buffers
before and after a volume control if you want.
The thing here is to try to make a buffer that is very neutral. Given
the simple task, it’s pretty easy to construct simple buffers with very
low distortion and noise and very wide bandwidth, all without negative
feedback.
There are lots of different possibilities for buffers, but we are going to pick my favorite:
|
Any! active stage/s introduces noise hum and distortions, increase their gain and you increase those as well. This statement is still false. So it’s best to use as "most" as you can from the "passive" Master
volume (which has virtually no noise hum or distortions), and use as
little as possible "gain" from the active stage. Couldn’t be simpler. Perhaps. At least it could make sense. The above comment does not. What were you trying to say? Nelson Pass:
" A “passive preamp” - just an input selector and a volume control.What
could be better? Hardly any noise or distortion added by these simple
passive parts. No feedback, no worrying about what type of capacitors –
just musical perfection." You cherry picked that one... What could be better? Nelson answers that:
Is impedance matching an issue? Passive volume controls do have to
make a trade-off between input impedance and output impedance. If the
input impedance is high, making the input to the volume control easy for
the source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And
vice versa: If your amplifier prefers low source impedance, then your
signal source might have to look at low impedance in the volume control.
This suggests the possibility of using a high quality buffer in
conjunction with a volume control. A buffer is still an active circuit
using tubes or transistors, but it has no voltage gain – it only
interposes itself to make a low impedance into a high impedance, or vice
versa. If you put a buffer in front of a volume control, the control’s
low impedance looks like high impedance.
If you put a buffer after a volume control, it makes the output
impedance much lower. You can put buffers before and after a volume
control if you want.
He confirms what I have maintained- a buffer at the input and a buffer at the output of the control are both helpful. |
Of course I do, don’t be ignorant, if you increase the gain of an active
stage you increase not just the signal what’s coming in but everything
else including noise, rf ,hum any tube or transistor noise is also
amplified when you add more gain to an active stage. George, the only way this statement can be partially true is if a Baxandall-style volume control system is used. Since that employs opamps, the statement is thus false on account of the inclusion of the words 'tube or', although a Baxandall control usually employs some sort of RF filter at its input. So its not clear where you are going with this, but clearly it fails to address my prior post if that was your intention. |
since the volume control (THE MASTER!!) has to be before the active gain stage in order to prevent overload. So the noise floor of a tube line stage if well-designed will be a constant. So the noise floor of a tube line stage if well-designed will be a constant.
This is total BS, yes the "Master Volume" is in front of the active gain stage and should be at or around 2-3 o’clock for normal listening, 5 o’clock or nearly full for loud, and 12 o’clock for low listening.
If the active gain stage has a "gain control" as in this case, and has it’s gain increased so then the "Master Volume" is at 9 o’clock for normal, this will increase noise, distortion and whatever other non linear distortions the active stage has, sent to the amp, hence to the speakers.
Note: The words THE MASTER!! were added to my post after the fact. George, your post here is incorrect. Clearly you don’t work with active line sections or you would know that. If anything, turning down the volume will cause the gain stage to have less noise. This is because the input is getting closer and closer to a dead short as the volume control is turned down. And we all know that an active gain stage is at its least noise level with the input shorted... If you look at most active line sections, the balance and volume controls exist prior to the actual gain stage of the line section. It is very rare for the controls to be anywhere else! |
XLR balanced connection offers better common - mode noise rejection and improved signal quality over the RCA connection. If your preamplifier, power amplifier, or active speakers offer XLR balanced inputs, you may use a pair of XLR audio cables to connect the ******** DAC’s XLR Balanced Audio Output to the XLR input of your device. @phomchick No, there is no way to tell from the above whether the unit supports the balanced standard or not. Here is the standard in a nutshell: 1) pin 1 is ground, pin 2 non-inverted, pin 3 inverted (the latter two are reversed in Europe) 2) the signal travels in a twisted pair usually within a shielded cable. 3) Ground is ignored by both output and subsequent input; it is used for shielding only. 4) The output is capable of driving low impedances of 2000 ohms or so without distortion or loss of bandwidth (in particular in the bass). Of these four points, the latter two aspects are generally ignored by high end audio. This causes the cables to exhibit artifacts where they otherwise would not. Here’s an easy test, which many balanced components fail. If you connect to an output XLR, using only pins 1 and 2 and get a signal with no hum or buzz, the standard is not being supported. This is because the return circuit for pin 2 is ground rather than pin 3. If the unit supports the standard, there won’t be a circuit between ground and pin 2 or 3, and with no circuit you get a buzz. |
So while you can make good arguments against passive volume controls and
uncontrolled cable interactions, these are not a factor in my system.
Thus, in my system, my statement above that there is no amount of money
that can be spent on a preamp that will sound better that a straight
wire, is a perfectly true statement. @phomchick I agree on the first sentence 100%. But not on the last; most high end audio manufacturers don't support the balanced standard even though XLR connections are used (and to be perfectly clear, I'm not sure whether that includes Oppo). So if you were to add a buffer or active line stage that *does* support the balanced standard, you *may* find that it is an improvement. If you have to audition the cables to get it to sound right, that's a clue that the balanced standard isn't supported. |
it will to many still sound better than any active preamp, with or without gain. This statement is false, on account of the word 'any'. "Some' would make it accurate. A buffer or gain stage added to a passive with good impedance and gain match can only add distortions/colourations. This is a common myth. The problem is that passive controls can do this too. So the trick is to figure out what works in your system- and the vast number of options is why this is so tricky. I would have thought the least amount noise would come if the master is
at or near full for loud listening, then the gain level if it is
controlling the "tube gain" it’s then only increasing any noise to a
minium level, as tube noise/distortion increases at the same rate as the
gain will.
Most active tube line stages are not built in this manner, since the volume control has to be before the active gain stage in order to prevent overload. So the noise floor of a tube line stage if well-designed will be a constant. And just so we're clear about that noise floor, on speakers of 105db, to even hear a good tube line section's noise floor, you have to put your ear as far in the midrange horn as you can just to hear it. IOW its a non-issue, as most people don't use horns (which are the only speakers that are that efficient) anyway. Sure there is. Gain means an active circuit. And all active circuits add
noise, distortion, phase and frequency distortions. If you don’t need
the gain from the preamp, you can avoid these problems by eliminating
the preamp.
There are four functions that any line section/preamp should be able to do, and this includes passives except for the first point below:1) add any needed gain2) control volume3) select source4) control the interconnect cable between the preamp and amp Of these, point 4 is the least understood, even by preamp manufacturers. It is certainly misunderstood by all passive control manufacturers (unless they are in it solely for the money, and some are as we have seen earlier on this thread)! If you are wondering how a passive can have more coloration than an active, its due to point 4. This is because the interconnect cable can impose an artifact as we all know, since the cable industry is a multi-billion dollar/year industry in the US, and everyone reading these words has heard cables make a difference in their system. But if the preamp is properly designed this does not have to be the case. BTW, this is what the balanced line system was devised to do and it is very successful if one adheres to the balanced line standards. But a properly designed single-ended line section can reduce cable interactions quite dramatically as well. **No passive** can do that! The reason I quoted the latter post above is that most sources make no provision for cable control- and thus are subject to cable artifacts. If the manufacturers of source components had their act in gear, we would not be having this conversation! “No preamp” is a straight wire. It will add no noise, no distortion, and in 99.9% of cases no frequency response anomalies.
There
is not a preamp made that has the same characterics. Thus, there is no
amount of money that can be spent on a preamp that will sound better
that a straight wire. It is now easy to see that the above post is false. Its based on the idea that cables have no artifacts, also leaves out the effects of capacitance and the like that are inherent in cables and makes the false assumption that a volume control is somehow the same as a straight wire, which it certainly is not! As a result, you can actually have an active line section with wider bandwidth that can indeed sound better than a passive and not due to 'pleasant distortions' either (since any properly designed active line stage will have vanishingly low distortion), but instead due to the additional transparency offered by cable control. The distortions created by amplifiers are far more significant! |
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”,
is a commonly heard refrain (really - I’m being serious here!). Maybe
they are reacting psychologically to the need to turn the volume control
up compared to an active preamp.
I suppose if I had to floor the accelerator to drive 55 mph, maybe I’d
think the life was being sucked out of my driving. Then again, maybe I
like 55. Nice and safe, good gas mileage…
Is impedance matching an issue? Passive volume controls do have to make
a trade-off between input impedance and output impedance. If the input
impedance is high, making the input to the volume control easy for the
source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And
vice versa: If your amplifier prefers low source impedance, then your
signal source might have to look at low impedance in the volume control.
This suggests the possibility of using a high quality buffer in
conjunction with a volume control. A buffer is still an active circuit
using tubes or transistors, but it has no voltage gain – it only interposes itself to
make a low impedance into a high impedance, or vice versa.
As per usual, George omits the rest of Nelson's words **after** the quote he usually trots out. I've included more of that text above, seems to me not for the first time on this thread. As you can see, it points out that passives can't do the best job on their own, and are helped out by the use of a buffer. I've pointed this out many times on these threads about passive vs. actives. What Nelson does not address is that a buffer at the input of the control is useful too. However, a buffer with no gain is going to have some signal loss. Its also *very* tricky to build a circuit with only a little gain without being on the edge of linearity with many devices, tube or transistor. So if you have a no gain buffer at the input of the control and a no gain buffer at the output, you may wind up with not enough voltage to drive the amp to full output. This is why there continue to be active line stages made, despite digital sources having higher voltage outputs for over 35 years. My best surmise is that George consistently leaves out Nelson's complete remarks because they don't fit his world view. |
