I'll never go back to an active. I had a CAT SL-1 III with factory-simplified signal path (unneeded switches removed), and its lack of transparency, compared to a homemade Shallco ladder stepped attenuator passive, was intolerable. Others will tell you that passives can't provide dynamics or maybe things like "rich mid-range harmonics". These can only be artefacts, but if you want them, a passive won't be your cup of tea. You will need good output stages from whatever sources you use, but a lot of modern sources are fine on that score. People will also tell you that you can't use long interconnects with a passive and that imput impedance of your power amp must be high. True to some extent, but I've used my Shallco passive very successfully with Pass Aleph 3 power amps, input impedance 23K ohms, and with 8' interconnects (using paralleled Aleph 3's as monoblocks), and Nelson Pass told me, when I told him this, that many Aleph 3 users have given him similar reports.
I've had 3 passive preamps over the last few years, and can say that they are good in some applications. However, there are tradeoffs.
Yes, you will likely have to spend some money to get similar purity and transparency to what a good passive offers! I have heard some very high end active preamps, like CAT's, Audio Research's top stuff, Conrad Johnson, etc, that are extremely accurate sounding(if you can quantify that). However, Passives are, in my experiences, DECIDELY LEANER and less dynamic sounding than active preamps!..this is the down side. They simply don't have the gain to boost the usually lower output signal from a source component to give it enough life! Now you couple that with the fact that MOST traditional "passive" loudspeaker units are relatively dynamically inept, and you get the antithesis of what "dynamic transparency" and realism is!! I think running passive is worth trying if you never have tried it. And it may just be the ticket for what you listen to(i.e, small instrumentals and vocals). Yet you won't get any sock you in the chest, hard hitting, dynamic effortlessness or ease to your sound. You will get more of the flat 2 dimmensional dynamics compared to what is more capable from a better active preamp.
Now, if your using very high input sensitivity amps, or low impedence source components, and even high sensitivity speakers(even active speakers), you might just find a passive is the right preamps for you!
But, for most peoples set-up's, I think they'll find passive preamps better choices for most circumstances and practicalities.
I have both a passive and active (in 2 different systems in the house). Passive can be very very good, but it does require more effort in component matching. You can get very poor results with passive when components are not selected carefully. Also, cables and long interconnects, as mentioned can create problems seldom seen in active pre-amps. Lastly, passives rarely have the ergonomics and features of actives--due to their necessary simplified circuitry. This can be fine for certain applications, but really doesn't work for others. In the end--the final verdict--both can work well. Passive can provide better sonic value for the same (and much less $), but with the caveats mentioned.
OOOPS!...made a mistake on my last comment.
I meant to say that most people will find "active" gain preamps a better choise in the majority of circumstances, not passive units!
I have used passive preamps on and off for many years. In the right system they are unbeatable, however they make stringent requirements on the rest of the system i.e., a high input impedance and good sensitivity from the amp input, good, low impedance and load tolerant output of the driving component and compatible cables. It's a lot harder to get it all right than with an active preamp but there can be very positive rewards. Good luck.
I've just got my dealer pissed auditioning TACT RCS2 in my current setup.
I've got back to McCormack Line Drive in passive mode.
I feel I'll never go active again.
Thanks alot for the thoughtful and enlightening responses.
For the price I'm paying the experiment should be fun.
The DAC which will be providing the output voltage can be tune up to provide 5v of output power. (Normal is 2.5v)
Of course it's really not a preamp if it is passive.
You are correct. In truth the passive unit is nothing more than a potentiometer or simply a manual voltage regulator.
One of my DAC's has the option of running line level out to a preamp or through a stepped passive attenuator system. Since the DAC was built to produce 4 volts of output, lack of drive when going passive is not a problem. I've tried it both ways within the same system. Only difference that i could tell was that i had greater versatility in terms of being able to switch inputs and volume levels with the preamp in the system. This tells me that this preamp is doing exactly what it was designed to do: select the input and pass the signal as it receives it.
Other than that, my experience basically mirrors most of the other comments. Passive systems are harder to set up and typically lack bottom end warmth and overall dynamics. Not my cup of tea but that doesn't mean that others don't like it or prefer it over an active preamp. Knowing Tom's level of "tweaking experience", i'm sure that his system might change my mind about the whole subject. Sean
I recently purchased a Placette passive to compare to my BC21 tube pre and a solid state. I paired the Placette with a Pass Aleph 3, as did Tom above, which does not have particularly high input impedance or sensitivity, and with Dunlavy SM1, which do have resonably high 91 sensitivity. If there was a loss of dynamics with the Placette, it must be subtle because I sure have not noticed it. In fact, while at a Modesky, Martin, Wood concert tonight (great new album by the way), I was thinking how much more striking and better sounding their material was on my system at home.
So Flyfishnz, how does the Placette compare overall to the BC21?
I owned a Silver Rock Passive with the 0db gain. They also make one with 6db gain. It uses a completely silver wired transfomer / potentiometer. I've had other passives, and I agree with most of the comments here regarding the drawbacks of passives. But the Silver Rock has none of these issues. It is the most transparent pre-amp I've ever heard, and shows none of the weaknesses of passives. It is dead quiet, as it acts as an isolation transformer as well as a pre-amp. For more info, please read the TAS review of it where they compare it to a $15000. active, and also the TAS review of the Halcro amps where they used the Silver Rock with them. It is expensive for a passive and looks like hell, but it sounds great! I sold it because I went to a Tact (2.2X).
A bit off the subject, but I'm very surprised that Marakanetz didn't like the 2.0. I've set-up two 2.0s for friends (they don't have laptops), and the Tact is stunning. Both of these guys now agree with me that the Tact is a "must have" in any system. I also thought that the volume control was completely transparent when the Tact was used only for this purpose. We went back and forth with it in and out of the system using a passive and an active pre-amp. Perhaps you could comment further on what you didn't like about it?
Successful use of a passive preamp is system dependent. In a highly resolving system the passive should be more accurate to the source signal. The ideal "passive preamp" simply attenuates the source signal without capacitors or transistors (which change the sound). Therefore the signal retains more of its original flavor and sounds less processed and more pure. Loss of bass and dynamics is a due to a mismatch between output level and input impedence.
Ideally, the attenuator should be built into the source component circuit for the most accurate sound. This is because source signal does not have to travel through simply another component (less circuitry), and there is one less connection, and one less interconnect. It appears that some manufacturers realize this, like Audio Aero and Resolution Audio.
Well said, Ultrakaz. In my current situation all I upgrade is only and only source since I've set up the correct amp/speakers for the listening room. Any attempt to bring in active preamp wasn't successful at all. The bass was tighter but the deapth and imaging were missing a lot.
BTW: Are you sure that Audio Aero and Resolution Audio have an analogue passive attenuatter instead of digital?
Yes, the Audio Aero and Resolution Audio both use an "analogue" attenuator as opposed to a digital one. I think Wadia and Accuphase use a digital one. This, of course, is important because it subtracts information to attenuate the sound.
I have FT-Audio LW1. Much better than with pre, which adds noise and veil as well as bass. I now use Cary 306/200 with ANALOG volume option, and connect directly to the amp. Similar, but more convenient than having passive, as I have only one source.
The statements above are only to my ears, with my system, in my room. As always, you have to try in your room with your system.
I like them both, but held off on a more critical audition and decision on which to keep until I received some room treatment from auralex, which I put in today. Sometime in the next week a friend and I will be doing an extended listening to the BC21 versus the Placette, and I will post a note here regarding our thoughts.
Thanks C. I'm currently considering a Placette pre and very much look forward to hearing your thoughts.
Has anyone listened to the MSB multiple volume control? It looks like an interesting product, highly configurable, remote volume, and cost is seems reasonable at $800. Thanks for any input.
I have gone from passive to active for practical reasons. When my child was born in seemed prudent to move as much equipment away from curious fingers as possible. Longer interconnects were required and the demands for a sucessful passive system were no longer possible. In acitive mode I get a bit more bass impact and dynamics. In passive mode a bit more purity of sound. These effects are pretty subtle. One curious thing I discovered was that my purely passive device sounded better than my active device with gain stage removed (via a switch) and used passively. Now this all went on some time ago. Hence for reasons of lack of funds and extreme caution re: expendenture on a new hobby (read cheap)I wasn't using the best equipment. One of the best amplification rigs I've heard was the "First Sound" with a passive line stage and a dual mono class A amp. The key to making passive work is to do your home work, the requirements are fairly strict. Whether passive is better, I don't know. I would consider acive first, but wouldn't rule out passive. Interestingly enough, some of the origianl manufacturers of passive line stages went onto unity gain devices. I have not tried them. Perhaps this is the best compromise? The future of digital amplification may make all of this moot.
Simply put, all else being equal, ANY active sytem CANNOT be as TRANSPARENT as passive. If your source output impedence is low, as it should be, speakers sensitivity and amp input senstivity not too low, and listening volume not abusive, your home free. In my experience, these factors rarely add up to a problem but can. Having done alot of experimentation, parts quality makes a big difference. If you're not afraid of a soldering iron, constructing your own is not prohibitive and , of course, puts you in a position of upping parts quality for less money. Stepped ladder attenuators using even low cost 1/8th watt resistors(smaller is better) will blow away the best pot. A few hundred $ in parts and a few hours will blow away ANY "preamp" including the CJ ART; unless you're after additives and colorations, in which case there's no argueing and personal taste rules as always. Why waste money?
Or why not run without a preamp,or even an Amplifier. No Amps? Ooops. No way! Yes. Run the output to a highly sensitive speaker like the avantgarde. Well technically the lows are handled by its built in amplification,the mids and highs by the cd player.
Very weird configuration,but i heard one on demo.
A little late perhaps to jump in on this thread, but I agree with Ultrakaz to some extent. I do like analog volume controls built in to the source component, and have owned many CD players and DACs that allow me to go directly into the amp. I think that any system will sound better without a pre-amp. But the Silver Rock is different. It functions as an isolation transformer, and causes a much blacker background. More details emerge from the music, which is now grainfree and pure. It is the only pre-amp that I will use.
I recently located a Carver Lightstar Direct passive pre to
match my Carver Lightstar Reference Amp. With the two stable-mates together, I was expecting miracles. The tranparency was immaculate but the overall sound was thin. I would welcome any suggestions that would help make the sound fuller and richer.
I agree with Glreno, that transformer-based passive attenuators are the way to go. I'm using a DIY Bent Audio TX102, which should be very similar to the Silver Rock (I'd like to know how they actually compare), except that it's a bit more versatile and not quite as expensive.
What I want to point out is, that transformer-based passives don't have any of the drawbacks (impedance matching, requirement for short interconnects) of the resitor-based units and as such they are IHMO the best thing since sliced bread.
Can't imagine trying to drive my Aleph monos without their Aleph P!
Best for more than one source component: a remote-controlled passive attenuator (stepped/potentiometer or even transformers) next to the power-amp inputs... = negligible cable influence.
...and to meet the topic: I can't imagine a better pre-«amp» than a passive one. Possibly a transformer design sounds best of all. (I have a 10-kOhm Alps potentiometer.)