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In Reply to: Are Passive Pre-Amps Lacking at Lower-Mids Compared to Active Pre's posted by waj4all on May 14, 2011 at 19:50:37:
This post is for the benefit of those who, having seen the title, came to this thread hoping to find the answer as to whether the premise is true, or not. However, considering that this long thread (68 posts) was, perhaps, dominated by issues having nothing to do with the premise, it may be difficult for the reader to form an accurate impression. The following, in roughly chronological order, is a condensed listing of the responses to the ISSUE only. Only one response, from each respondent is shown here, unless subsequent responses from a particular respondent expands on the issue at hand - repetitions are avoided, so as as not to confuse the issue. ALL who responded to the PREMISE are shown here, as far as I'm aware. Those who did not, are not.A brief note on the lower-midrange; so far as I'm aware, this is the region where a lot of the resonances of many instruments are portrayed. It also incorporates the trailing edges and fade of notes such as portrayed by many instruments in live performance. The reader must decide how realistic the reproduction can be without it (or if it's compromised in any significant way) if this turns out to be the case. It is, indeed, a fact that passive systems display slightly superior clarity over active pre-amps, from high-mid to high frequencies. Whether that clarity comes at the cost of realistic performance in the lower-mids is the question we're seeking to answer. Some advocates of the passive system have described the lower-midrange performance of actives, generally, as; a 'pleasant coloration', 'enhancement', 'flavoring', etc. It is up to the reader to decide whether this is so, or whether this 'coloration' is actually accurate, more or less and, therefore, representative of the tone and general characteristics of live instruments.
Regardless of the respondents' preferences, the question is: Are passive/preamp-less modes 'less prominent' at the lower-mids compared to active pre-amps. For ease of tally a simple 'Y' for yes. or 'N' for no, is ascribed to each respondent. So as not to be disrespectful, in those cases where the respondent prefers the passive, while seeming to comfirm the premise - a '?' is indicated. In these cases, it is left for the reader to ascribe 'Y' or 'N' in tallying the 'votes' - based on what is actually said, regardless of preference expressed.
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Y - Dave Pogue - I agree., I've heard lots of systems incorporating passive linestages/controllers that sound very good to me, yet I still prefer my active pre (Aesthetix Calypso) and now I know more about the "why" of it. Thanks for posting this.
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N - E-Stat - Don't experience that , with my Audio Research preamp. Perhaps the Coincident is "enhancing" that region.
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? AbeCollins - I tend to disagree, What passive setup did you experience and the rest of your associated gear?
This is too much of a generalization about passive preamps. There are good ones and bad ones, and all of them require much more careful synergy between the components. And I'm not talking "synergy" in a hocus pocus or vague mythical way.
In my experience, the ideal passive setup will have source components with robust low impedance signal output and possibly higher voltage output than typical. My Cary 306/200 CDP comes to mind with it's 3vrms output. The power amp should have a good amount of gain AND sensitivity, and the speakers should be somewhat sensitive so you're not having to crank the volume way up to get modest listening levels. You want to have enough adjustment range in the passive so you're not at the extremes. Short interconnects with low capacitance are also desirable.
In my experience and in my system at the time, I found the respected McCormack TLC-1 to be very transparent but "thin" sounding in the mids. I found the popular Adcom GFP-750 to kill the dynamics in passive mode and not especially engaging in active mode, although Stereopile raved about this mid-fi piece several years ago. (I had to try it for myself, I didn't like it).
It all came together for me when I tried the Placette Passive linestage. It was not only unbelievably transparent and "clean" sounding but it had good midrange, bass, and treble extension. There was no "bass suckout" or lack of midrange. On the other hand, it didn't "color" the midrange and enhance it as so many linestages will do, especially vacuum tube units.
Dynamics were also excellent in my passive setup, probably in part due to the strong source signal and gain and sensitivity of the power amp in the system along with somewhat sensitive speakers. I didn't have to "crank it way up" in order to make the system come alive with dynamics.
Yup, the passive setup that I had was probably one of the best sounding I had assemebled. I also very much enjoyed the Cary SLP-05 vacuum tube linestage with incredible midrange. Incredible because like so many active linestages available, they are "voiced" to enhance certain regions and to cater to certain tastes. The Placette and other good passive linestages are none of that. They don't add to or subtract from the source.
So to make the generalization that passive linestages lack midrange is all wrong. What is your reference? A warm and robust sounding tube linestage? Nothing wrong with enjoying that type of sound - I certainly do as evidenced by my current setup. But to say that all passives lack midrange is just plain wrong. It may just be a matter of system synergy and your reference point.
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N - Mkuller - I've been using a preamp-less system - ...for about 10 years now - Wadia CD player connected directly to my Manley tubed amps.
Midbass and lower midrange are just fine.
It is all about system matching and there are few absolutes. Try it and hear for yourself.
Personally I don't care much for Salvatore or Stereo-Mojo.
Anyone can find just about anything they want on the internet these days.
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N - Robert C. Lang - Very well stated....., And it's not just because I, too, employ a Placette Passive Line Stage (after making in-system comparisons with 4 other actives and one other passive).
It's funny for years many (the uninformed, especially) would take broad brushed swipes at "passive pre-amps" (symptomatic of being uninformed) as being weak in bass, dynamics, with rolled off highs. Now a new frontal attack against "all" passive line stages that "they" are lacking in the lower midrange. But you hear anything in these pages.
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? - Clio09 - Not in my system. I use a Lightspeed attenuator and Slagle autoformer volume control that I built. No lack of dynamics from wither, nor do I sense any lower-mids lacking. I have/had active preamps too. While I admit impedance mismatches can certainly derail the performance of a passive, with the exception of active buffers that I have, I haven't heard an active preamp that didn't flavor the sound somewhat. While the flavoring could certainly be appealing to the listener, it's my opinion that it is not true to the source, and that is what I'm after and my preference.
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Y - Morricab My experience mirrors your own, All passive preamps I have tried (attenuators or transformers) robbed something from the music in terms of dynamics but it could be the lower mids lacking as you described. I think it has something to do with attenuating the signal just prior to entering the amplifier. An active preamp usually attenuates the signal and then gives it a big boost (i.e. gain is maximum) and its this driven signal that goes into the amp. Usually the gain is quite high (20db) and you have the umph of a good power supply behind it as well (assumming a really good preamp).
I have found that the problem is minimized if you have a VERY good output stage on your DAC, phonostage etc. but most are not good enough
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And yet you use and active preamp?? I have tried many "passive" preamps, even digital attenuation from the source, and NONE sound anywhere close to as dynamic and right as a good preamp. Even a not so good preamp has more get up and go.
I had a DAC, Monarchy Audio M22B, that had 6V output levels (or 3V take your pick) specifically for driving passives. Never sounded anywhere close to what it sounded like with an active preamp.
BTW, your system looks like it should be pretty good sounding so don't think I am bashing your system. I am just curious about the fact that you personally use an active preamp when you had the Placette before I assume? Also, a tube amp typically has a high input impedance...perfect for passive...or so we are led to believe.
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"I agree about the importance of the "warmth" region. In my case, I find no difference in tonal quality between using my ARC preamp vs. DACT attenuators with a GamuT CD-1. Only a loss of transparency and stage width using the preamp.
"You are sure about this? I have always heard a loss of dynamics when going passive and any slight gain in transparency is offset by a distinct loss of drive and bleaching of the tone. This has been true with many amps, speakers, sources etc. and many passives.
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Interesting, of course the problem with a passive design is that it is always taking something away from the signal and giving nothing back. Almost all active preamps first attenuate and then feed that attenuated signal into a relatively high gain section and then out to the amp. This means that the full drive of the preamp is going into the amp and not a resistor before going to an amp.
This could be why you were losing the decays earlier with the passives. It takes a VERY good preamp not to smear the sound somewhat on leading edges and most are not up to it. I had one of the best passive pres ever made (little known company called Purist from Germany) and my Silvaweld preamp still walked all over it in terms of tone and dynamics, although maybe not leading edge transients.
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? - David - If I may pop in here..., ...in my system a passive unit I previously used had greater or equal dynamics to two different tube preamps (Audio Res. LS-7 and a Decware ZTPRE) and had much better leading edge transient attack or impact. The one area where the passive was lagging was in the trailing edge where the sound wasn't as sustained as it was in the actives.
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? - Say - This post is to no one in particular. Instead it is an observation of mine over the years of listening with both passive and active preamps.
First conclusion I have is that people will state their taste more than anything else. The second point is that the system will dictate how the preamp sounds just as much as the preamp dictates how the system sounds.
After owning and listening with the ARC LS7, Golden Tube Audio Sep-1, CJ Premier 14, VAC Renaissance Signature and Promitheus TVC I can draw the following:
The ARC LS7 - is a lower rung model with good mids but limited highs
Golden Tube - I liked it till the volume control died on me. Fixed it but found better units later on. This preamp did a swell job once I changed the dual triode to a better NOS.
CJ 14 - good everything but still the golden glow.
VAC Ren - better then the previous units at everything, and still a golden glow.
TVC - best at the upper registers. Clear and uncompressed highs. Good at bass. Good at midrange. The only fault is that it didn't bloom like the CJ did nor throw an expansive soundstage like the VAC. Nor did the TVC have the mid/bass bounce and guts of the others till...
...and this is the best part. Till I got it right. Now it has very good mid bass. I just had to tweak my system and find an amp that suits those needs. I cannot go back to the actives with a fine TVC around unless I want to sacrifice detail. I lose too much (much is a relative term so take this as a relative observation) information for the sake of mid bass I now have anyway after tinkering.
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Thanks for the support of my honest and personal opinion waj4all.
Regarding trailing edges, one thing I did notice and still do is that tubes will do that better than my TVC in comparison. Not that the passive is a slouch in that department but all of my active preamps did have the trailing effect in spades. Here is the kicker, with a decent tube amp the passive will allow trailing edges to flourish. It just won't create more by itself. Thus if a solid state amp is used down goes the trailing edge too.
As for leading edges I would rate the TVC as good but not best. Mabye its the transformers that take a millisecond or too off the timing. I don't really know. Therefore speed will be sacrificed a smidgeon and, thus, sustained decay only when...the amp is poor in that one area.
We have tradeoffs with each. Its down to a matter of choice and synergy one can get with what one has. With the Apogee speakers I can get the TVC (passive) to sing and give a rather good effort in the 0-60 sweepstakes yet even the Golden Tube preamp (active) was no slouch in that department either. The Vac even better.
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That's it folks! Hopefully, this will be helpful to some in forming an opinion as to which is better for them. My own vote is not included, nor is my own opinion disclosed in this post. Thanks to all who participated. And special thanks to Morricab who seemed to bring a calming influence over the proceedings and, perhaps, influenced a re-focusing on the real issue at hand. My apologies to you, Morricab, for not replying directly, but I'm sure you'll understand that I was in the midsts of a storm, at the time.
If, btw, anyone else would like to contribute, please feel free to do so. Your preference is appreciated but, with a view to helping others, it's more important for you to state the differences you've found between active and passive, if any, in their performance at the lower-mids (including the trailing-edges of notes, etc.).
Thanks again, to all!
WAJ
Edits: 05/18/11
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Follow Ups
- Active vs Passive Pre: The Answers to the Premise - waj4all 13:41:46 05/18/11 (0)
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