If your CD player has a volume control on it and can easily drive your power amp into saturation, i see no reason to go active in a case like yours. Sean
If a player only has one set of outputs with variable output, adding additional gain stages will only amplify what the player is already passing through its' built in attenuator.
On top of that, so long as the player already has more than enough output and is capable of easily driving the amplifier to full output and beyond, one should not run into the typical "lack of dynamics" situation that many people feel occurs when running passive or direct.
In addition to all of the above, Cdc mentions that the cdp being used has a buffer stage built in, so the player itself should be less sensitive to cable changes, etc... Adding another gain stage that is sensitive to cable / impedance changes could easily reduce the sound quality that such a design is capable of providing.
For the record, i typically prefer active preamplification for multiple reasons. BUT, and that is a BIG "but", if everything is accounted for with a well designed cd player and it is your only source, i see no reason why this should not work out quite well.
As mentioned above, try it and see. Personally, i would want my cd player to be capable of producing at least 3 - 4 volts on a steady state if i were going to do something like this. Running a player with lower output levels may get you into trouble. Obviously, this is an amplifier dependent situation so there is quite a bit of lee-way involved. Sean
I've got an Adcom GFP-750 so it's easy to compare passive vs. active. With a good CDP with output buffer, I don't see much difference in dynamics. I think the CDP output power supplies may also affect dynamics but maybe someone with more experience would know better?
With a cheaper CDP which did not have the output buffer, there was a fairly noticeable loss in life to the music. Even though it has 2 volt output.
But I think a goldpt or DACT passive attenuator may give better transparency than the Adcom. The Adcom seems to lack ultimate transparency. At least that's what people here have said going from Adcom GFP-750 to a Pass Aleph preamp. The other option I have is to upgrade the volume or capacitors on the Adcom.
I don't see how anything could be more transparent than a DACT attenuator. But if there is an impedance problem, maybe an active pre is necessary. I've read some passive pre's have a resistor network to correct for these potential problems.
Some passive pre's are very expensive. Look at Placette ($1,500) or FT Audio's Little Wonder ($600). That sounds like a lot of money for a volume knob in a box. Does anyone have experience with either of these?
So the main question I have is: other than dynamics, is the purpose of an active preamp to be a tone control to further tweak the sound of the system?
The question is not that straight forward and everyone should in this case integrate components.
Is there any CD-player or phono-pre that is able to throw 8...12Volts on the output out here? I know that not too many and if you need that kind of output to feed your amp than you wouldn't get away without active preamp.
Many poweramps are in reality sort-of integrated ones with high input sencitivity and gain that is very close to integrated amp except the volume control: McCormack, Counterpoint, VTL, Bryston... SS amps even have an extra input high impedance small signal stage making three all together: input stage, driving stage and the output stage where the input stage in reality is a preamp! Do you need to go active in that case? I'd say no... If you already have preamp why get another one on your signal path? In case with tubes an input tube with its local feedback signal return as a buffer tube as well so you don't even need your CD-player or DAC to be buffered.
Another aspect is that poweramp sencitivity is usually rated Volts/per FULL output power and the sencitive ones go from .6V upto 2V depending on delivered output power. Do you always listen on the peak powers? Than I'd say it's wrong. The best volume position is where the amp "feels" the best.
I've done measuring and plotting graphs experimentations of many amplification devices FETs, Bi-polar and vacum tubes and figured that excessive attenuation before input drastically changes the bandwidth curve of ANY amplification element. The amplification ratio 'dB v.s. bandwidth depends on the working region of the input/output characteristics. Mainly the IMPEDANCE characteristics of the any active element will dictate the shape of curve for any imput signal.
The best and simple example to demonstrate for casual listener is to bring to your system TWO active preamps connected in series(I know that that is to extremes but very and very obvious). Use the first preamp for the volume and on the second one set the volume to the minimum. In result you will only hear bass and upper freequencies with midrange laid far far back. The same situation but to the less degree occurs when high gain active preamp is used with high sencitivity amp.
There are simply a couple of philosophies in audio electronic devices and different manufacturers take either one of them or combine both and thus every component does perform its own task for what they've been designed.
Shortly saying one would say that preamp should be designed for the minimal task and the other would say that poweramp is a critical component... The rest is for your ears and experimentation.
P.S. you can easily search through the older posts here to find out about successfull integration of a passive preamps into your system.
Sean nailed it. I have played around with many passives (transformer-coupled and regular resistive, etc.), and none of them did EVERYTHING right as opposed to the active linestages I have used. Even with most actives, something has to give, but the best I have heard are the Audion preamps from the UK- basically a buffered line stage, point-to-point silver wired simple circuit using 3 6922's for the phono stage and one for the line stage. The Premier Quattro 4-box version (dual outboard power supplies) is da bomb...
I did not have good results in my system going cd player direct, music was lifeless. Even the famed audio aero sounded lifeless too me going direct. But it is you who has to be satisfied with the results not anyone else. The music is much more satisfying too me utilizing an active pre-amp. So as others have suggested you need to experiment to determine what works best for you. Happy listening
I went down this road already for a while. I think there are probably ways to make passive preamps (or no preamp) work, but you really have to be willing to tweak your system and try lots of combinations out, and you have to have quality source and amp components that deal well with no pre. That being said, I could never make it work in my system, and the sound from my new active (Plinius 8200 mkII) is pure heaven compared to my experience with a passive setup.
Sometimes something seems like it should work but just doesn't.
There's a lot of good stuff that's been said here, from seasoned experience. You can pretty much pool what has all been said, and try to get an idea of what may or may not happen in your experiences. I can pretty much look at each post and concure with some point, or all points, and say the scanario's mentioned here would likely be similar to what you might find if you experiement yourself. The key is that you'll HAVE TO TRY YOURSELF TO FIND OUT!
An easy way to compare what a passive preamp would sound like in your sytem would be to just get a good CD/DVD player that sounds very good through the analog out's, and that posseses a "gain control" or "volume control" and connect it dirrectly to your amp!(perhaps some sources have different gain and impedance, so beware) You can compare this passive set up to an active preamp you might be considering, then you can not the differences. You might also try tube preamps and better active SS offerings to compare that as well.
A buddy of mine has a Berning ZH270 with Merlin VSM-M speakers. We listened direct to the Berning through a Bel Canto DAC 1.1 and also through his CAT pre. We both much preferred the sound through the CAT pre. Much more enjoyable to listen to. We didn't feel the sound lacked the detail, etc. It retained the detail but became more musical. That's not to say through the Berning was bad. Hardly. It sounded wonderful. Through the CAT it was more musical and enjoyable.
i have never heard a passive preamp / direct out that had sufficent bass and mid-bass response. the mid bass respsonse is very slow and puddling.
also passive is very lacking in dynamics.
take a listen to a passvie unit / direct out to a nice tube /hybrid preamp and there is no comparson.
Try a bat vk30, audible L1, AR ls2bmkII etc... the soundstage will also snap into focus.
these are decent pre-s that are less than $1000.
With a passive preamp direct you should be looking for an amp with an input sensitivity under 1 volt. I use
a Gamut D200, and a passive preamp with the D200 set at it's .775 volt input sensitivity, with 5 meters of interconnect cable between the preamp & amp. Having just tried a active preamp for comparisons, there's no lack of dynamics, resolution, bass or treble response. As Marakanetz points out the midrange presence is affected.
In my system,the active preamp moves the midrange forward
as the volume is increased. Allowing that the power amp/speaker and impedance interfaces are good, adjustable input sensitivity on the amp and variable gain controls on the preamp would allow a user to dial in the sound they want, but there aren't many products that offer that feature.
I have also the adcom gfa 750, when I used the passive
mode, micro and macrodynamic disappear.From my experience
I tried cd players with volume, one is from high end co.
and I also have the AH Cd player, without preamp the music
is lifeless.WADIA IS THE ONLY CD that performs very well.
Remember Wes Philip is the one who review the adcom CLASS
A,Its design by Nelson Pass if Iam correct.If i were you
I will find a weaker link on your system, I do believe
the adcom its one of the best preamp there.