Zaikesman
To answer your two questions of 12/22:
#1 - At comparable listening volumes, the passive offered excellent and equivalent detail to my new ss pre, much better than my tubed pre (Sound Valves VTP-101i); however, the ss pre imparts a more life-like quality to the music at equivalent volumes that brings me a step closer to the recording studio or live venue. The passive I have is a CI Audio VPC-1. Perhaps a higher quality passive (McCormack TLC-1, Placette?) would have compared more favorably.
#2 - I have not done the bypass comparison with my ss pre as you have, but I think its designer/builder has. Please
visit the following site:
http://www.musicalconcepts.com/MD_preamps.htm
Does John's paragraph, ("How We Test") amount to the bypass comparison you've done? His design philosophy and testing approach were major factors in my purchase decision (go to the "Used/Demos" link from the Musical Concepts homepage for details on my pre - it is the MC Custom two piece SP-3 prototype with the 1.2 FARAD power supply).
You also asked about my system components for context purposes:
Musical Design T1 Signature CD Transport
Perpetual Tech P1A processor
Perpetual Tech P3A DAC w/Level I Modwright mods and Monolithic P3 power supply
Musical Design SP-3 Preamp
Pair of Blue Circle BC-28 power amps in vertically biamped configuration
Wire - Acoustic Zen MC=Zen digital, Revelation Audio Prophecy I2S, Cardas Golden Reference ics to preamp, Stealth MC7 ics to power amps, Daniels Audio Omega speaker cables
Power conditioner: Balanced Power Technologies BPT-2.5
Joy and peace of the season to you and all who read this!
jb
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Zaikesman, I applaud your steadfast devotion to the truth. Audiophiles as a group (it seems to me) exhibit too much of the kind of abdication of critical thinking we see in people who take shitloads of vitamins and supplements, or visit psychics, or etc. etc. |
Agreed, and I won't open the can of dbt! |
I guess I would describe it as "Something in/Something different out", whether that something is garbage or gold. A person is allowed to prefer the differences conferred upon the output by the preamp. And I acknowledge that whatever signal degradation is caused by the preamp, it might still be less than the degradation caused by an electrical mis-match between the source, cables, and amp input when running direct, or by some type of passive attenuation device, depending on the system context. My main point is that the only way for an audiophile to know any of this for sure, in their system, is to go ahead and perform the bypass test. |
Z-man: The "garbage" phrase is a popular metaphor, meaning in this context that the quality of the original source cannot be much improved downstream by a generalized application. |
Jb0194, I am clear that you prefer the sound of your system with your new preamp in place, rather than your previous one or the passive device you allude to. It is not surprising that your new custom preamp would sound better than one you describe as "modest". As for the passive attenuator, it would interesting to find out more about what type of device this is, and the context of its usage in terms of sources, amps, and cable runs. Two questions: Can you be more expansive and specific about what the "more compelling" differences are? And have you actually tried a bypass comparision such as I propose with any of the three units?
Jayme, although I don't believe that either of the preamps I used in my test was 'garbage', and also have never felt during normal use that what I hear from those preamps is 'garbage' (I've owned worse before), I don't disagree that it may take a larger preamp expenditure than I have made (can make?) to greatly ameliorate the situation I describe using my units, and I basically stipulate that much in my thread-head post. |
I believe your post, Z, can be narrowed down to this: garbage in, garbage out. Or: if one prepares a piece of dung for dinner, pouring the finest wine reduction sauce over it will not compare with serving a fine cut of prime tenderloin. Of course, tenderloin costs more than a bit of sauce. In audio, as in cars, the best does cost more. Some may argue that their "fast and furious" Hondas match a Ferrari. But that is mere product envy. Life, alas, is unfair. Audio imitates life. |
I concur with Drubin's post of 10-15-02. I have no formal education in elecronics. I've just gone through a quite unintentional comparison among a modest tube-based line stage, a passive, and custom solid state preamp of simple circuit design with premium parts and battery-like power supply (while waiting for the latter to be built). Active preamps do add more circuitry to the signal path than passives, but whatever my new active is adding makes the music much "more compelling" and the difference is profound. |
AV, you continue to totally miss the point. I have tried to be as clear as I know how about what it is I'm testing for here and why, so unfortunately there is nothing else I can say to you. Maybe if you read through the thread again, slowly, you'll catch on. And/or simply try the test for yourself and the light will dawn. Otherwise all I can comment on, is that you and I can't actually disagree about something if you don't understand what it is that you're taking exception to in the first place (and I doubt that if you did, we would really be in disagreement as much as you seem to think). Happy listening! |
I don't want to take much more time in this thread as it does not relate to reveiwing products. However, your exercise here seems a bit pointless as 1) You admit that you do not listen to your source components at unity gain, therefore, whatever your findings here would mean that you would need to have some sort of volume control inserted in the path. Perhaps this test would be more revelant if the assumption is that you would hear an improvement because you are by-passing switching, volume control, etc. However, what if one finds the opposite? That is without proper buffering, your source component does not interface well with the power amp. 2) Your assumption that all source components will drive short cables and drive most consumer power amps is questionable. Yes, many audiophiles have reported that passive volume controls work well for them. My experience is that they don't, I can hear what adding passive resistance does when passive resistance of various types are added to the signal path. If the end result is that you will need to use volume controls, switching, and/or buffers, then they should be included in the test. |
Before I respond, let me say up front that I truly appreciate AV_specialist's interest in this thread if it is sincere, but either I am missing something or I need more explanation or justification of his seeming position, so here goes:
1) Umm...Duh! That's kind of the point of the test. (It's actually input switching, not "output switching".) Please go back and reread my description of the test and why I set it up the way I did if you did not pick up on this.
2) You show me the source component with an output stage incapable of driving a typical 1m or 2m cable run into an imput impedance of at least 20K ohms with least 1v to 2v, and I'll show you a source component that can't 'drive' a preamp any better than it can a power amp. Almost any digital player, DAC, or separate phonostage made will provide a low enough output impedance with enough voltage to interface with a typical amp input. Almost all amps (excepting some pro-type gear) will provide high enough input impedance, voltage sensitivity, and gain to be driven by a such a typical source. Of course, for listening you may desire more or less gain, but in general, unless you are restricted to employing very long interconnect runs or use a very low-gain amp, almost anyone could do my proposed test at unity gain and get instructive results. (In fact, even in the case of a setup where the interface was clearly disadvantaged by not employing a preamp, the results would still be equally instructive as far as ascertaining the effects of the preamp. Whether the results are in favor of the preamp or not doesn't negate the value of the test itself.)
AV_specialist, I don't mind being critically questioned, but I don't see what you're trying to get at. Either you're just trying to poke at me for the amusement of it, or you haven't really read carefully what I've written above. Why don't you just come out and tell me your agenda here? You obviously are in some way 'against' the test procedure I've outlined, but I have no idea why. I mean, if you simply prefer not to try this, then don't - but that wouldn't explain your coming on this thread to challenge me (your perfect right to do, and which I welcome), so I must assume you take a greater interest in this subject than merely not caring to bother with it.
If I had to guess why or what that agenda is, then I would suppose this: I believe many audiophiles tend to recoil at the idea of tests such as this because they don't really want to be made aware of the implications of the results. I am not saying that control over attenuation, switching, output buffering, or overall gain is unimportant in a system. I am not arguing against the use of active preamps. I use them myself, and will continue to do so as far as I can see. I do not normally listen to my system without a control center in the loop, and I have not owned a passive volume attenuator (yet). If I were to try one, I have no doubt that it would also suffer in comparision to the sound of the straight source, but not at unity gain as in my test, since that would involve zero attenuation, unlike an active preamp (for whatever that's worth).
But I do not for a second believe that putting the source signal through additional stages of gain and attenuation can in any way "improve" that signal, necessary as those factors may be for system control. However, it is true that a preamp may change the signal in ways that an audiophile could find pleasing, but without some sort of reference, the listener will never know for sure how to attribute those characteristics. The reference could be the sound of other preamps, and that is valid and is often done, but I am suggesting that the reference also include the unprocessed sound of the source itself, because that is the real baseline for determining how intact a preamp is capable of transmitting the input signal.
None of this means that other methods for controlling overall gain (volume) or driving long cable runs will necessarily be superior to a good preamp - they often won't be for any given source component or system layout. It also doesn't mean that in some situations, a preamp may not fortuitously balance out some sonic characteristic of a source component, amp, speakers, or cable, but complementary colorations do not equal transparancy to the source. That preamps exist at all in these days of all-digital rigs and stand-alone phonostages is mostly for ease of system configurability and convenience of control. They are no longer a necessity in the same way a power amplifier is. The saying "The best preamp is no preamp" didn't come into existence for no reason.
You can claim none of this really matters since we are not actually going to listen to music without our preamps in the loop in most cases, and that point is perfectly true as far as it goes, if that is all you are saying. But I think audiophiles ought to be much more skeptical of claims made by manufacturers or in reviews suggesting that XYZ preamp is going to confer all these wonderful properties upon the sound of your system. The best that we can actually hope for is that a preamp do as little harm as possible, while at the same time providing the most good in return when it comes to system flexibility and control.
I advocate that audiophiles would do well to learn more about what their preamps are really doing in their own systems, and remain unconvinced by any protestations from technically aware folks who ought to know better than to argue against the potential worth of performing a simple home test. Such preampophiles will often have a proprietary interest in maintaining preamp fiction, which in turn can lead to the fiction about source components needing all kinds of help in order to interface with amp inputs, when in fact it's cables and passive attentuators they may in fact have difficulty interfacing with. (And on that last item, it's as much [or more] the output impedances and insertion losses of passive attenuators creating difficulties for amp inputs and cable runs, as it is their input impedances creating difficulties for source components, that can cause them to suffer in comparision with active preamps. Despite those potential problems, many audiophiles still report better results using passive attenuators, given appropriate conditions, so I take all the Chicken Little hoopla about the dangers with a large grain of salt. I still want the availability of extra gain myself however.) A little personal knowledge about the performance of one's gear should be nothing to act scared of.
P.S. - If you have problems with what I am saying here, you should click on my threads and read my post about a test setup for looking at DAC performance and the effects of upsampling as implemented in an upsampling-switchable DAC. You ought to love that one... |
1) Are you inferring that volume controls, buffer stages, and output switching in preamps do not affect their sonic characteristics? When you listen to rec out or unity gain outputs of a preamp, you are by-passing all of the above mentioned.
3) Not true is not good enough. It depends on the buffer stages of the source components. |
First question: I'd want to spend time doing this test in order to learn about my preamps and what they are doing, not only in comparision with each other, but to the unadulterated source.
Second: Of course not.
Third: Not true. It's passive resistive volume controls and long cable runs that source outputs may (as opposed to "usually") not interface well with, not amplifier inputs in most cases. |
Would you care to elaborate why you would want to spend a lot of time doing this comparison test? Do you listen to music always at unity gain of your source components? Have you considered that unbuffered outputs of source components usually do not interface well with power ampfliers inputs? |
Actually Zaikesman, I own Museatex equipment including MTR101 amps that the gentleman was reviewing. When you have all non-mainstream equipment and someone finally discusses something you own, whether in favorable or unfavorable terms, its a bit of a treat. Oh well. |
Jetter, need I reiterate for you that this is *not* a product review? This post, if I do say so myself, actually delivers on the promise implied by its title line, should you choose to click on it - something that other post you refer to did not (as of right now, mine is still the only response to that three-sentence 'review', which should be some indicator of how worthwhile it was). If you have some pertinent criticism of my post here, then please, by all means contribute it. (And if you care to see how I do write a product review, you know how to find that too.)
Drubin, I just want one control center in my system, without having to go around back and pull wires all the time, and with the gain I sometimes require to listen at higher levels. I realize there is always, at least in my own opinion, going to be some sonic tradeoff for this convenience. I know I wouldn't be the first audiophile to have ever concluded that a preamp is basically a necessary evil. :-) |
Zaikesman,
Wasn't it you who yesterday took the time to belittle someone who posted a review on a Meitner MTR101 amp because it did not fit into the audiogon definition of a product review?
I was already thinking about what type of person has the need to do that to someone else and then post his own nonreview just like he took someone down the day before to do it. |
But Zaikesman, if the preamp can't make the sound better, why would you not want to go direct or passive, at least for digital? |
JC, I appreciate your input, but I think you may have read some things into my post that I did not intend. I am not trying to make a case for running direct, and I do realize that my preamps (list prices about $1,800 to $3,000) are not SOA. Neither are most folks' preamps, and neither do most folks want to run direct or passive. I am also not trying to solicit advise concerning my own preamp situation in particular with this thread, which is why I'm leaving out the make and model info, since I don't want my comments taken out of context.
My post is just intended to explore the notion of employing a bypass test to look at preamp performance, and to see if other members have had experience with this kind of procedure and what their results may have been. In my own case, where I feel confindent that my DAC, at least, is just as capable of driving my amps' inputs as my preamps, I admit I am skeptical of the notion that a preamp could not only fail to cause *some* signal degradation, but could actually make the sound 'better'. I acknowledge that I don't have epxerience with the best preamps, but rest assured that I have no intention of removing the preamp function from my system. I just want to know exactly what it's doing. |
I meant to say "sources that would seem good candidates for a passive, such as the theta's", but I should add "also from output voltage and what I have read". The theta seems to benifit less from going passive, while my phono, seems to benifit more from going passive. My findings so far are opposite from what I have read would be the case.
In the quicksilver line stage, the volume is before the line stage curcuitry. The path is fron inputs, to the rotary switch, then to the other swicthes (mono, ect.) then to the attenuater, then to the active curcuitry. I have added two leads going to output jacks from the attenuater, so the active and passive are in parrallel coming from the attenuater each with it's own set of output jacks. It is actually what seems to me a good quality passive, given the stepped attenuater and quality of jacks. The only inconvenience is that the active reverses polarity, so I have to reverse the speaker cables whenever I go from one to another, or else I would put in a switch.
You bring up interesting point about the bass frequencies, I have not payed that much attention to it insofar as a mismatch, perhaps I should. I have looked only at rolling of highs as a mismatch that just would'nt work well (sound quality is the main thing, but I am refering to situations where it is not possible due to the interfaces to evan consider).
I wish I knew a way to invert polarity on a single ended signal. |
You say you don't want to introduce specific preamps into this equation. I find that frustrating since that can make all the difference in the world as to how this test turns out.
You bias your test in the beginning by stating that if you don't recognize the benfits of running direct you must have one whizbang of a pre amp.
I have done comparisons with customers who were using Tenors without a pre, Audio Aero straight into their amps and passive devices using nothing more than naked Vishay resistors on their amps. All who have heard a benefit when switching to transformer coupled pre. I have attached one such thread from a die hard passive fan.
It seems to me your test is not real world because your trying to make a case that direct is better when comparing it to your solid state pre-amp or some one's pre which may or may not be that great of a pre. In that case a dircet feed is going to sound better. I have always agreed with that. My argument is that you can't make a generalization of which is better based on this kind of a test.
The impedance mismatch alone of the driving device and amp is reason enough for active gain stage. Comparing to a capacitor coupled preamp is still a compromise.
I have owned many!!!!!! players with direct outputs, passive devices including the Placette, First Sound (when he made them) EVS, Reference line etc. So I have had much experience with these devices. I know I have been down this path before. I have issued challenges regarding this. So far every person who has taken me up on the challenge has gotten away from their passive or direct devices.
"The system is so much more visceral with the M-5. Everything got better. I don't know how anyone could think running the AA capitole atright to the tenor would be better than this"
Why do the Audio Note preamps sound so much better
I took Joe over at JC Audio up on the offer of a shoot out. Actually it was the second time. About nine months ago I went over and had a shoot out between my EVS Nude Attenuators and the Kora triode preamp. I have to give Joe credit he agreed if you could live with the inconvenience and lack of flexibility that the EVS attenuators sounded as good.
But I made a bad mistake today. I went over and did the same shoot out with the Audio Note M5. I should have never done this. The M5 made the attenuators sound dry and lifeless. The M5 sounded prettier with much more top in extension without ever sounding bright. It was more transparent and fuller bodied at the same time. And the layering and the soundstageing was just beautiful. This is disturbing to me for I have been a big proponent of passive, especially the attenuators since you even eliminate a set of interconnects and a power cord. Why does this line stage sound so much better.
bilbondo@hotmail.com
08-02-02
08-15-02: ralph@atma-sphere.com
The Audio Note, EAR (E11??), the big Jadis and Atma-Sphere (P-2) preamps are the only high-end audio transformer-coupled units out there to my knowledge.
Transformer-coupling is common in professional tube gear, particularly from the 50s and 60s. This is because the equipment had to match to the 600 ohm balanced line standard (which is still very much around today). Tubes coupled by output coupling capacitors would never be able to play any bass driving a 600 ohm load!
We built the P-2 (discontinued when it was replaced by the MP-3) so it could drive the 600 ohm standard as well. The nice thing about the 600 ohm standard is that it ameleorates the role that interconnect cables play in the sound of the system, which is why the standard has been used for the last 5 decades by the professional recording and broadcast arts. Its always been a puzzle to my why audiophiles are so slow to embrace the same standards, despite having the same concern about cable qualities. This has spawned the high-end audio multi-million dollar/year cable industry.
We're an OTL manufacturer, but we've been a major supporter of balanced line technology for the last 14 years (mostly due to prolonged exposure to the recording studio); our preamps support the standard using direct-coupled ouptuts, which is the only other way to do it as capacitors won't work (since no-one would take a tube preamp with an electrolytic output coupling cap seriously...). IMO, its a shame that more manufacturer's aren't wise to what's happening here (sorry for the hype blast).
ralph@atma-sphere.com
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Zaikesman, I was thinking of my own personal dilemma with my two preamps. The (active but no gain) Placette, which is very, very close to adding or subtracting nothing at all, and the First Sound, which can sound glorious and more musically convincing in some respects, yet sounds entirely different from the Placette. |
Drubin, what I've noticed in my tests is more of a subtraction from the sound than an adding to it, which I guess is good sign in theory. For instance, piano can lose a little of its sparkle and percussive incisiveness, rendering it just a little veiled in comparsion. Stand-up bass loses some heft and definition, becoming less pitch-precise and more rubbery. On the other hand, some sounds do seem to gain unwanted artifacts; a half-opened hi-hat cymbal sounds more like two pieces of metal clashing against one another when listening to the DAC straight, but when the preamp is inserted, the sound becomes more akin to indiscriminate white noise - could this be the result of added intermodulation?
That's my SS preamp, though; with my tube preamp, there are losses to be sure, but you do notice right away a certain subtle tonal quality (which I like to characterize as 'sunny') is lent to the whole presentation. It can be attractive once you get used to it, but that is certainly something which is added, probably low-order harmonic distortion, and I don't know how it can be considered to make the result sound 'more like music'. This preamp definitely sounded more like music than my older cheap SS preamp that departed long ago, which was grainy, shrill, and flat in comparision, but it doesn't IMO improve on the straight feed from a quality DAC. |
Basement, I'm not completely sure about this, but I think most preamps place the volume attentuator after a gain stage, so it might be that taking an output straight from the attenuator bypasses the output stage, but is not totally passive. The loss of bass when you run in this mode could very well be due to the interaction of the volume pot's output impedance with the load presented to it by the amp and interconnects when the normal output impedance-lowering buffer stage is not present.
I'm a little confused by your fifth paragraph, but maybe you put 'passive' in some spots where you meant to write 'active' (also, your phonostage is actually going to possess the highest voltage gain of any of your source components, although not probably the highest output voltage). In the next paragraph, I'm sure the input impedances you refer to on your amps must be K-ohms, not ohms, but again, it would be bass frequencies which would be rolled off if the input impedances were too low, not the highs (it's cable capacitance which can roll off the highs.) Help me out here Sean if I've screwed up any of this! |
We're still on slightly different pages here Sean, so maybe it is me who's not being clear. What I am suggesting is to stay with one set of outputs from the DAC (could be either one - the variable ones could be useful for achieving an overall volume that doesn't blast away the subtle differences, but once it's set, leave it there and treat it as fixed), or to use any other source. The idea is to focus on what *the preamp* is doing to any line-level signal it gets. To do this, you have to maintain the same interconnects and I/O jacks, and just swap the output leads on the preamp from the active, normal ones to passive, direct ones like processor bypass. That way, you can compare the sound with and without the effects of the preamp's gain and attenuation stages, while keeping the connections and cables constant. To do this, you must set the volume control on the preamp to unity gain, wherever that may be. What you are describing is comparing the sound of your DAC's attenuation to that of your preamp's, which is a different comparision, and one that only matters for that particular source component (it does tend to confirm that your preamp must have a quite transparent gain stage and jack complement, as well as your interconnects being very fine, since you're losing one set when you go to the DAC's internal volume control, and as we theorized above, it could mean that the two attenuators behave very similarly, but your test does not isolate the preamp or maintain all the other variables as constants - it's a legitimate and useful test, but a different test nonetheless). |
I have a quicksilver line stage that I have done a simple mod on- I have taken the leads from the tape in jacks and unsoldered them from the tape switch and soldered them in parallel with the output of the attenuator, so I have both an active on one output and a passive on the other, all using the same exact switches and attenuator.
I have never seen much sense to a preamp being an improvement, after all, all we really need one for is to switch between sources and volume control. Why pay big money for something that is suppossed to do as nothing as possible, why not do nothing in the first place?
There is another side to the argument that says a matching devise of some sort is nessessary for the best sound evan though a passive may work. while of corse we all know this is system dependant, and obvious because different components have different input and output qualities, there seems to me to be much more to this, and I find it intreguing.
Needless to say, I find the passive more transparent, (but realize that the quicksilver is not supposed to be the most absolutely transparent preamp possible). The passive does not seem to always go as deep in the bass as the active does, and while it may seem that the extra depth that the active does is due to either the effect of gain, or the fact it is tubes, I'm not convinced that it is artificial. The deepness that I am referring to is not just more bass that is always present, but rather deep bass that it seems is suppossed to be there when the program calls for it.
And also, I find that sources that are suppossed to be good for driving a passive and not good for for a passive (due to the output impedences) don't seem to be following the rules. My theta cd player seems to benifit more, or suffer less from a passive, while my micheal yee phono amp which has the lowest gain of all my sources, seems to benifit the most going passive.
Also, amps that I have tried this with that I would think would benifit from an active stage due to thier input impedences sound better with the passive, both a pse studio IV (50 ohms) and a hafler dh-200 (33 ohms). No loss of high frequencies at all. This seems to be true no matter how much I have to crank up the volume to drive them.
These have all been with only 1 meter interconnects, and I have yet to try long ones, and I plan on trying more amps. All of my comments have been thinking only of transparency, or what I am believing to be accuracy to the signal, but I am not really sure if while at the same time I am losing information and details going passive, that the active is not the most accurate to what the signal is intended to be. The quicksilver is neutral, I can say that, and right now I am enjoying the option of going either way. I'm on the fence. |
Zaikesman: I have done exactly as you stated. Sorry if i did not make that clear. I ran the fixed outputs from the DAC into the preamp and then fed that into the amp. I then switched over to the variable outputs of the DAC which directly drove the amp via the DAC's built in stepped attenuators. I could tell no difference between the variiable of the DAC fed into the amp in "direct drive" mode and the line level out of the DAC feeding the preamp which fed the power amp. This tells me that the preamp is either extremely neutral or that the stepped attenuators are "coloured" in a manner that is exactly the same as the preamp in question.
The "straight wire bypass" device that i was talking about allows you to actually put another preamp, power amp or both in SERIES with your existing "reference system". It comes with a device that allows you to gain match the system so there is no difference in volume. You can then manually switch between just your "reference components" or your references with the other components placed in the signal path to see if there is a difference. You can set up the switching device so that you can see if all of the components are active or you can do it in a blind and random fashion. If you can hear the difference with the "test components" switched in, they are either "coloured" or you are experiencing loading problems with the specific gear in question. Sean
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You're not a freak. In some ways, what you propose is threatening to some of our core beliefs as audiophiles. There was a thread not too long ago about which component is most important, and many people weighed in with preamp. At times, I must say I agree with that. But it's also fundamentally irrational if you believe that the job of the preamp is to switch and attenuate (and maybe add gain). The mainstream audiophile press has steadfastly avoided seeking the truth on this matter and us sheep audiophiles have followed suit (not singling anyone out). It's scandalous, really.
On the other hand...What is frustrating is that a great preamp can make a system sound more like music even through it may well flunk the bypass test. It is adding to the sound--how else can we explain it?--yet doing so in a way that is musically compelling. |
Sean, your result would seem to maybe indicate that the attenuators in both your preamp and your DAC are of roughly the same quality (I take it that you normally run the fixed outputs from the DAC and use your preamp for level control). Have you ever done the comparision I describe above, using the feed from either the DAC's fixed outputs, or from the variable outputs set to a constant comfortable level? That would tell you what the contribution is from the preamp alone.
(FWIW, it seems from the lack of response to this and previous posts I've made along these lines, that not too many other members are interested in trying to do this kind of isolation testing on their gear. I'm a little surprised, to tell the truth - I find it fascinating and informative, but maybe I'm just a freak! :-) |
Zaikesman: I have a DAC with dual outputs i.e. one that is line level and one that is fed via a stepped attenuator with the capability of 4 volts of output. I have tried listening with the stepped attenuator feeding the amp directly and with the line level outputs feeding one of my preamps. Quite honestly, i could not hear a difference.
If i can make arrangements with a local individual, he has a "straight wire bypass" contraption that Quad built for a select few dealers. Supposedly, there are only about four of these in existence. This can be used to do what you are doing AND be done under DBT conditions as it can be set to do random switching with the unit in or out of the circuit. While it is surely not a "mandatory" listening tool, i think it would be kinda cool to have and experiment with. Sean
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