11-28-10: Egidius
..thanks for your clarification! Good to know there is background behind a statement ;-)
I cannot judge 381 vs s7i, they will have similar problems.
Interesting point about the Digital pre - but:
isn't it always the case with a DAC giving out the full power (i.e. 100%),
or you mean to say, they could make a purist version without attenuation sounding - pure?
i think your question is could wadia make a cd player that had both fixed outputs and variable outputs. while you do see that feature in some cd players with integrated preamplifiers, it is unnecessary for wadia to offer such a feature. the reason is that the wadia preamplifier operates in the digital domain. the way that the wadia preamplifier operates, it attenuates signal volume digitally when the output level is less than 100 but does not attenuate the signal when the output level is 100. it is only after the digital signal level is determined that the a/d is performed and an analog voltage delivered on the analog outputs. so if you don't want signal attenuation, set the output level to 100 on the wadia. this unattenuated signal is equivalent to a "fixed" output that you might see on some other units. when you send the output from the wadia to the preamplifier, you should set the wadia output level at 100 and then control the volume level (in the analog domain) at the preamplifier. of course this unattentuated signal is not actually a "fixed" signal because you can vary the output. but since the varying is done in the digital domain you don't have the situation that you would have if the attenuation were done in the analog domain. in that case, you would perform the a/d conversion first to generate an unattenuated signal. this analog signal would be in the analog domain. one copy of the unattenuated signal would go to "fixed" output terminals. another copy of the unattenuated signal would go to preamplifier circuitry that would allow you to control the attenuated signal level, also in the analog domain. the signal output from the preamplifier circuitry would go to variable output terminals. the point that i am trying to get across is that since wadia does preamplification in the digital domain, you don't need 2 sets of outputs. since the wadia does preamplification in the digital domain, if you set the digital preamplifier level to 100, then you are sending an unattenuated signal to the a/d circuit. thus, analog output from the a/d circuit is like the "fixed" output. however, if you set the digital preamplifier level to less than 100, then the wadia attenuates the signal in the digital domain. it is the attenuated digital signal that is sent to the same a/d circuit. the a/d circuit then outputs an attenuated analog output signal. but to the a/d circuit, there is no difference, it just receives a digital signal and converts it. the a/d circuit does not have to know whether it has or has not been attenuated in the digital domain. however, where it can make a difference is that you can lose resolution through the process or digital attenuation. the source material from a redbook cd has 16 bits of digital resolution. the wadia operates with 21 bits of digital resolution. you lose about 0.5dB of volume with each step in the digital preamplifier control. thus, you can drop the digital preamplifier output level to about 65 (from 100) before you are prone to begin losing resolution in your digital signal. as you start losing resolution the signal can start to sound "thin". where it can also make a difference is when the signal output from the wadia is not loud enough. in that case you can adjust the maximum output signal level. the maximum output signal level from the wadia is over 4vrms. a 4vrms signal level may not drive a power amplifier into clipping, but it is pretty close, so you are probably not going to have any need to supply a voltage higher than that to a power amplifier even if you use a preamplifier. based on the discussion i have read here, even if you set the digital preamplifier output level to 100 (i.e. output an unattenuated signal from the wadia) there are some for whom the signal sounds better if it is passed through a preamplifier before it is sent to the power amplifier. if that is your experience as well, then you should send the output signal from the wadia into a preamplifier. that happens to not be my experience, so i prefer to drive the power amplifier directly from the wadia. i go through a preamplifier only if i want to play music at low volumes (where i am concerned about loss of signal resolution) or in cases where i need to use the preamplifier to get additional signal gain (beyond that which i can realize by driving the wadia directly into the power amplifier). if anyone is interested in learning more about the principles of wadia operation there are several white papers on the wadia website. |
06-26-10: Krellfan2002
I have a Wadia S7i at home and play with the Pass XP20 and XA160.5 but I prefer the preamp. Without the preamp I miss some body and dynamics. For me the preamp adds something.
the statement above makes absolutely no sense to me. the preamp can only work with the signal being provided by the source signal. so if the preamp "adds something" then what it is doing is coloring the source signal. wadia provides variable outputs where the preamplification is performed in the digital domain. the biggest problem that i have observed is when you adjust the variable output level too low. in theory, once you get below an output level of 65, you are starting to lose significant bits in the digital stream. in theory this would translate into less resolution. if you are at an output level of 75 or above, you probably aren't losing any significant bits. the other problem that you can encounter with direct connection is that with some low volume level source material (typically classical recordings since volume level is rarely a problem with popular recordings) the playback volume can be lower in comparison to connection through a preamp. by default wadia provides an output voltage of about 2vrms (i assume this is the output measured from the single-ended outputs and so i assume that the default is about 4vrms when using balanced outputs). as i stated, this is adequate for most recordings (for reference, power amplifier gain is usually measured based on a single-ended input signal level of about 2vrms). however, if it isn't the volume can be adjusted to produce a voltage output of up to 4.25vrms by setting all the internal DIP switches to the "open" position. if that output level is still not sufficient for the source material, then you would need to use a preamplifier. but presumably, in this case you are using the preamplifier to provide additional signal amplification with accurate reproduction of the source, as opposed to provide coloring of the source. of course, if coloring is what you want in your preamplifier (which is basically what you get with tube amplification) then that is entirely legitimate since all this stuff is a matter of personal preference. the point i am trying to make is that if you seek "transparency", then you aren't going to do better than direct connection from the wadia to the power amplifier; the potential limitation being that the direct connection may provide insufficient signal gain depending on the source material. |
11-27-10: Egidius
@paperw8 have you tried what you are explaining?
It's just, the statement by krellfan might not be wholly unexptected, if the pre substitutes something otherwise missing.
if your question is: have i driven a wadia directly into a power amplifier? the answer is yes. if your question is: have i driven a wadia s7i directly into a power amplifier? the answer is no, because i have a wadia 381 [i will leave it to the reader to determine how much difference that should make]. if your question is: have i modified the output voltage delivered by the wadia by flipping internal DIP switches? the answer is no because when i drive the wadia directly into the power amplifier i almost never set the output level of the wadia at 100%. generally i set the output level in the 65% to 85% range depending on the recording level of the source material. to be more specific, i drive the balanced outputs directly into the power amplifier and i drive the single-ended inputs to a preamplifier. i primarily tend to drive the wadia through a preamplifier when i want to listen late at night. i live in a residential area, so i can't blast music late at night. when i use a preamplifier i set the output level of the wadia at 100% and vary the output volume at the preamplifier. the reason why i do this is because the sound tends to become thin when you turn the digital output level at the wadia too low (as i described earlier). but as i stated, ultimately all of this stuff is a matter of preference. if it sounds better to you when you drive the wadia into a preamplifier, then you should drive the preamplifier from the output of the wadia. but what i am telling you is that when you do that, you aren't getting greater "transparancy"; instead, what you are getting is the sound produced by the wadia after it has been colored by the electronics in the preamplifier: that is the "something otherwise missing" to which you are referring. |
11-28-10: Chris10an
I own a Wadia S7i, and I have ekspermitteret with preamps with my S7i.
The conclusion was very clear. There is a HUGE difference between preamps, and there is also no doubt about, that a good preamp does it _much_ better than the digital preamp built into the Wadia S7i. For those who may doubt my conclusion, try using a Classé Omega MK III, Tidel Preos or Viola Cadenza.
i don't question that the wadia s7i sounds better to you when going through a preamplifier. but to make this point clear, you *always* go through the digital preamplifier with a wadia; there is no digital preamp bypass. in your case, the output of the wadia digital preamplifer drives the input of your preamplifier; and then your preamplifier drives your power amplifier. |
11-27-10: Rtn1
The volume control in the Wadia is decent. But, it is no match for a great preamp. A preamp can provide a more natural presentation with dynamics, texture, layering, and body.
what you are describing is a preamp that is, by definition, *not* transparent, but rather one that colors the input signal. it's fine with me if people want preamplifiers that color the input signal; it just seems crazy to me to read "audiophile" reviews that rave about how "transparent" this component is, or that component is, when in reality what they are seeking is a particular coloration.
11-27-10: Rtn1
In comparison, the (wadia) digital volume control can sound constrained, 2-dimensional, and less involving.
my question to you is, how do you know that the source material was not recorded so as to sound "constrained, 2-dimensional, and less involving"? it is my observation that the quality of recordings can vary widely. i mean, for all you know, the wadia could just be faithfully reproducing the signal being provided from the source material. if all you do is "trust your ears" while having no idea whatsoever about the underlying operations that produce the sound, all you can do is offer subjective observations about how the end result produced by the entire system sounds to you. but you most likely don't have enough information to ascribe that end result to the performance of any one component in the system. |
11-30-10: Bar81
Unfortunately Paperw8, what you fail to realize is that the concept is quite simple. The Wadia is trying to do two jobs - that of a CD player and that of a preamplifier. It should come as no surprise that a top flight dedicated preamplifier, such as the Ayre KX-R, which is focused on a singular task, will outperform the all-in-one digital preamplifier in the Wadia.
you are comparing apples and oranges because, as i explained, the wadia preampliifer operates in the digital domain while the ayre preamplifier operates in the analog domain. so your statement is incorrect that the wadia is doing *two* things - in reality, the wadia does *one* thing: digital signal processing. since the wadia performs preamplification in the digital domain, that constitutes part of "digital signal processing" which is what the unit does anyway. thus, there is no need for separate "fixed" and "variable" outputs as i previously stated.
11-30-10: Bar81
Accordingly, you actually are entering into your analysis backwards since your basic assumption, i.e., that the Wadia produces an "uncolored" presentation, is incorrect. Rather, the Wadia is coloring the sound via the suboptimal volume control in its digital preamplifier.
i will accept your statement that the wadia colors the signal. in fact, wadia does something called "resolution enhancement". ostensibly, the purpose of resolution enhancement is to reduce DAC errors by randomly augmenting the signal. but notwithstanding the rationale, resolution enhancement is a coloration of the signal (although wadia's claim is that in the end you get a "truer" analog signal). however, that a wadia-colored signal is passed to the preamplifier so net net result that you get is a wadia-colored *plus* preamplifier-colored signal. it is then up to the individual to decide which sounds good to him. it's just that it is my preference to also understand how stuff works because that allows me to get a sense of which explanations make sense and which ones don't.
11-30-10: Bar81
With regard to your argument that there is no way to turn off the digital preamplifier in the Wadia; while that is technically accurate, even Wadia itself admits that the preamplifier portion of their players do the least harm to the signal as you go higher up in the volume range. Accordingly, 100 volume (i.e., using a preamplifier) must impose the least harm to the signal as it exits the Wadia.
i don't know how much you know about digital signal processing, but i explained all of this in one of my previous posts - it's the part where i talked about the 16-bits resolution and 21-bits resolution stuff. if you do understand this stuff, then i would suggest that you read the wadia white papers; if you don't, then those papers may be a bit hard to follow; even though i think that wadia tries their best to explain technical material in understandable terms. |
11-30-10: Bar81
I understand the concepts at play here and as I stated, I have owned Wadia gear for extended periods. Unfortunately, given your posts in this thread, it does not appear that you want to accept anything other than your own opinion. No use in further wasting my time. Enjoy.
you, and anyone else, can believe whatever you choose to believe: some people believe in santa clause, the easter bunny and the tooth fairy, but that's their choice. from my perspective, knowledge has value. the idea of "you don't have to read - just trust your ears" struck me as stunningly ignorant: if you "trust your eyes" you could draw the erroneous conclusion that the sun revolves around the earth... but don't take my word for it on how the wadia works. you, and anyone else here who can understand the subject matter, would serve yourselves well to actually read the wadia white papers that describe various aspects of the system. as white papers go, they are relatively short and not heavily technical, so they are fairly easy to read. the reason why i value understanding how stuff works is because on audiophile forums and reviews, i often read authoritative sounding statements that are patently ridiculous. understanding underlying principles is a way that i separate the wheat from the chaff...and believe me, there is a lot of the latter out there. |
12-03-10: Bombaywalla
Paperw8, I'm pretty sure that the Wadia resolution is 24 bits (& not 21 bits) after it upsamples.
i'll say this again: don't take my word for it, READ THE WADIA WHITEPAPERS and draw your own conclusions. wadia has several whitepapers posted on their website that anyone can download and read. |
12-03-10: Bombaywalla
OK, I see that I am right & you are also right - after upsampling (marketing verbage used by Wadia is "resolution enhancement") the word length is 24 bits (which is what I wrote) & then, after processing by DigiMaster algo, they chuck the least 2 significant bits & reduce the rez to 21/22 bits (which is what you wrote).
as you saw in the white papers, the wadia has a 22-bit DAC, so the wadia digital preamplifier operates on the 21/22-bit signal. that's why you don't start losing significant bits (from the 16-bit input stream recovered from the cd) until you hit a digital output level of about 65 (out of 100). each step in the digital output level knocks off about 0.5dB, so by the time you get to 65, you are down about 18dB, which effectively reduces the signal by a factor of about 64; i.e. the signal is about 64 times weaker in comparison to the unattenuated digital signal. this, in turn, effectively knocks off the 6 least significant bits from the 21/22-bit signal. thus, by the time you are at 65 on the digital output level, you only have the most significant 15/16 bits remaining in the original 21/22-bit signal and you are at the point where you are starting to lose significant information (since the original signal from the cd was a 16-bit signal). |
12-04-10: Bombaywalla
yes, Paperw8, thanks for taking the time to explain this to me but I already understand the concepts of DSP.
I agree that (100-65)*0.5 = 17.5dB, which you are rounding up to 18dB. I seem to have 1 issue in your calculations - how did you arrive at 18dB being an attenuation factor of 64??
it's a voltage attenuation of 18dB i.e. 20log10(x)=18dB. So, what should x be to get 18dB?
since each increment in the digital output level corresponds to 0.5dB, each increment of 6 corresponds to 3dB. the digital preamplifier is operating on voltage (and not power), so 3dB is a halving of voltage level. in the binary domain, a halving corresponds to 1-bit. so each 3dB knocks off 1-bit so when you knock off 6-bits you have reduced the binary value by 2**6=64. as far as actual amplitude, bits 17-21/22 are fraction bits but i am just speaking generally, so if you just consider the 21/22-bit binary word, each 3dB would correspond to a right shift of the binary word as you knock off the least significant bit. so, for example, the binary value 100 corresponds to a base-10 value of 4. however, if you right shift the binary value, binary-100 becomes binary-10, which is a base-10 value of 2. if you do a right shift on binary-10, you get binary-1, which is a base-10 value of 1. anyway, that's the idea... |
12-04-10: Bombaywalla
wrong! every 6dB (i.e. every 12 steps) is halving of the voltage amplitude. You correctly wrote that the digital amp works in the voltage domain & not the power domain but you did not understand that concept fully.
actually, you are incorrect. the basic decibel measurement is computed as follows: 10*log10(q1/q2) where q1 and q2 are quantities that are being measured (ref: http://en.wikipedia.org/wiki/Decibel). [wikipedia is not a peer-reviewed reference so you always have to view statements there with some degree of caution, so feel free to challenge this statement if you have a better reference - i just don't feel like digging through my own books since the wikipedia equation matches my own knowledge on the subject] as it turns out, power is proportion to voltage**2. so when the quantities being measured are power levels, and since power is a function of voltage, the equation for power can also be represented as a ratio of voltages: 10*log10((vo**2/r)/(vi**2/r)) [i am assuming equal resistance values for simplicity] however, because of the way that logarithms work, you can also express this equation: 20*log10(vo/vi) this is the equation that you presented - i'm just trying to explain to you how the equation was derived. so, a 3dB reduction in voltage corresponds to a 6dB reduction in power. you will notice that the wadia white paper refers to *volume* output. volume output is a power domain concept. so the wadia white paper on digital volume control indicates that you start to lose significant (i.e. non-interpolation bits) when the digital attenuation causes a 36dB reduction in *volume* output. i took a look at the wadia manual, and i think that there is an error in the manual. the manual states that there is a 0.5dB change in *volume* for each step in the digital volume control. from my calculations, and the wadia white paper on digital volume control, it appears that there is actually a 1dB change in volume for each step in the digital volume control. |
12-05-10: Bombaywalla
wrong! a 3dB reduction in POWER corresponds to a 6dB reduction in VOLTAGE.
unlike much of the subjective discussion in this forum, this is a factual matter; your *opinion* on the matter is irrelevent to the actual *facts*. |
12-05-10: Almarg
I haven't taken the time to read through most of this thread, but I'll just say with respect to the quoted comments that neither is correct.
A 3db reduction in power corresponds to a 3db reduction in voltage, for a given impedance. A 6db reduction in power corresponds to a 6db reduction in voltage, for a given impedance.
the reason why impedance is not considered is because you are generally looking at power at a given point. for example, when you measure output power, you are always measuring power at the output terminals, so there is no difference in impedance. in this case, what we are describing is the effect of the wadia digital volume control on either the voltage output level or on power output level. so if you do a decibel measurement on voltage, the voltage level is halved at each 3dB increment; if you do a decibel measurement on the power level, that too is halved at each 3dB measurement, but if you look at power as a function of voltage and perform the power measurement AS A RATIO OF THE CORRESPONDING VOLTAGE LEVELS, then each halving of voltage level corresponds to a 6dB redunction in power level (you need to pay particular attention to the capitalized section). at this point i have to say that i think that i have explained this as best i can. so if someone still isn't following this, then i can't help them and they will have to refer to other sources for further discussion. |
01-28-11: Inpieces
I also tried the level adjustment at my Wadia.
I use a JRDG C-500 and 381. If i lower the level, i can clearly hear that the sounds becomes less dynamic and full/punchy.
It's heard directly (- no question!), if i lower the level from 100 to 97.
as it turns out, if you connect the wadia to the preamp and lower the volume at the preamp you would notice a similar phenomenon. it's just a characteristic of the mechanical nature of speaker cones (not to mention the limitations of your own hearing and/or room acoustics) that volume level affects the sonic character of a musical presentation. |
just out of curiosity, as this thread is about the s7i, i am wondering if you any of you compared the s7i and the 381. from what i can tell, the main difference (aside from some cosmetic differences in the display) is that the s7i adds additional regulated power supplies so that more subcircuits have their own regulated power supply whereas in the 381 more subcircuits share a common power supply. i'm wondering how much that design change affected subjective impressions of the 2 units. |
02-01-11: Rtn1
Even when volume is matched, there is unacceptable loss of dynamics when the digital volume attenuator is used.
first, the comparison that you suggest is highly unreliable; it's just hard to listen to one configuration, change the configuration and then try to get the same volume level from memory. second, i agree that listen to a wadia in a direct connect configuration is likely to sound different from that of a through-the-preamp configuration. to that extent, if you prefer the sound of the through-the-preamp configuration, then you are going to prefer the "dynamics" because you just like the configuration better. that's not a matter of any "flaw in the technology" it's just a matter of your own preferences. i'm not suggesting that there is anything wrong if you say that you prefer the sound of the wadia through a preamplifier. for my own part, for some recordings i sometimes find that i prefer the sound of the through-the-preamp configuration, other times i prefer the sound when going direct to the amplifier. from my observation, the preamplifier acts as a kind of tone control that does change the sound character of the musical presentation. |
