Passive/Active preamps: pros and cons....


New to preamps...what are the advantages/disadvantages of passive or active designs? I will be only connecting one source (CD) to the pre...any thoughts? passive/active switch like the highly reviewed Adcom piece? any others come to mind? Also...in an active design...how much emphasis does the pre have in regard to the main amp signal?
128x128phasecorrect
Agree with Ozzy, passive in a system that takes advantage of it's (passive) advantages is very hard to beat.

I had a passive (using S&B trannies) also and the sound quality was steller in every area.

A system/room change led to much less than ideal conditions for the passive so I sold it and moved back to active.

I wound up going to my first tubed active pre-amp (Audioprism Mantissa) as I could not find an active SS design I could afford... or listen to for very long...outstanding mid-range quality will spoil you and is something the passive brought to my system...much like the almost passive Mantissa does.

Dave
I have a S&B TVC, agree with Ozzy62, and find the passives “lack of” perception is more like passives “don’t add” dynamics, colorations, etc. of active pres.

Compared to running direct - the TVC adds a tube like liquid, warm feeling in the mids, the highs smoother or slightly rounded, and pace more relaxed. The alteration are very, very slight, and much less than the actives I’ve tried, but not absolutely invisable either. Everything else seems untouched.

I haven’t compared it to many actives and would be interested in comparisons from others – like Ramses.
If you are a candidate for a passive then by all means get one. If your CDP has enough output at a low impedence and your amp is sensative with a high input impedence it should be fine. I connected my CDP direct to my amp and it has too much output and would have overdriven my amp on all CD's (no two CD's are recorded at the same level) What this means is my former active tube preamp (now retired) was really acting as an attenuator. Everything got better with it out of the loop. It was a very nice modded CJ pre. My CDP is also nice an MF Trivista which has a very hefty low impedence output. In my opnion many CD players do not qualify for passives. Try connecting yours to your amp direct first and see. Have a CD that starts out quiet and your remote in hand ready to push the stop button if it overdrives your amp. If it does not overdrive at anytime and say only produces a moderate volume level you are not a candidate for a passive. I use the Placette and love it. It sounds no different than with my CDP connected directly. I reburned some CD's @ -10db to do lengthy testing before switching to passive. I like Placette and the company is really great. I have tried a few other passives and did not like them as well. I would like to try a Bent which is TX-102 transformer based compared to Placette's Vishay resistor ladder. I think I would not like the high end but am open to anyone who wants to lend me theirs for evaluation. The Bent and other transformer based passives actually have about 6db gain, so I have read, the TX-102 is a step up X-former. Good luck!

ET
Electroid, it is precisely because most cd players are capable of driving amplifiers to full output that the Placette Passive was made. Unless it was simply a typo, I'm wondering why you think that most CDPs are not "qualified for passive". There's a reason why Placette decided to put in finer volume steps in the lower volume ranges. In most systems and sources, the Placette passive has more than enough gain.
Howie -- maybe he means that the volume controls contained in the cdps are not very good?
There seem to be many S&B users here. BTW, the 102 is NOT a step up, it ust has a +6 output tap on the secondary that one may or may not use (I, for one, don't).

The basic premise is simple: IF the source (cdp) has a reasonably low output impedance (mine has 22-50 max ohms) and the load is sufficiently benign (10kOhm or higher), then you're set for a wonderful musical journey. If the load is lower than ~7kOhm and the source impedance is high, then dynamics suffer... i.e. you;re losing energy across the "transmission line".

There's really no reason for an active line level device unless you need the buffer effect. Things are different when it comes to a phono (there, you need the extra amplification)!