Do all Passive preamps exhibit this trait

I think the simple answer is no. I have an old Adcom GDD1 that would change the sound whether in active or passive mode. I am currently running a Canary Audio CA-200 into a Spectron Amp and I can't hear it doing anything to the sound. Backgrounds are real quiet and the amount of detail is incredible. A lot of audiophiles have nothing but bad things to say about passive preamps - but I find it works well in my system.

It is all system dependent but the Belles GR8 passive I had was also dull in the treble. I guess I could have found a bright amp to mate with it but I felt that two wrongs didn't make it right. I also tried running two of my amps direct since they had gain controls but that wasn't very good either. So I've stuck to active preamps ever since.

You might be able to change cables and kind of get what you want. Kimber KCAG on the passive side and Cardas Golden Cross on the active side might get one of them "right." Just a thought.

Arthur

The idea of passive is to not color the sound? Get something like a creek OBH-12 which is as passive you get and see what your amp and speakers really sound like.

Typically passive preamps do not exhibit this trait, but depending on the rest of your system you may have trouble finding what you are looking for. A good passive preamp should not add or subtract anything from the equation. However, impedance mismatches and cable issues could cause the problems you are describing.

In my experience I have preferred transformer or autoformer based passive preamps versus their resistive counterparts. The TVC/AVC passives tend to match up better in most systems. Impedance matching is important with passives. Just changing the setting on the volume control could impact the output impedance on the passive. Also, since we don't know the rest of your system there are a few things you should look for moving forward.

1. Your source has enough output to drive the passive (2V or better with low output impedance).

2. Your amp should have high input impedance (50k or better) and be sensitive (1V or less to drive it to full power).

3. Try to keep cable lengths short between the source and passive and passive and amp. This is more applicable to the resistive passives, but probably a good practice with any type.

If it were me, after determining if my system was passive friendly I'd try a TVC/AVC and see what happens. Lots out there to try that you can find used for good prices. Promitheus, Antique Sound Labs, and Sonic Euphoria come to mind.

Also try reading this:

http://www.stevens-billington.co.uk/page102.htm

One other thought, try the new Pass B1 unity gain buffer preamp. The buffer eliminates the impedance issues and the circuit does not have a gain stage. Sounded really good at RMAF when I heard it there.

If you don't want to pay the Pass dollars Audiogon member Rawsonte has been advertising a couple DIY versions here for great prices.

Maybe that "more extension and detail" you experience with this pre-amp is exactly what makes it fatiguing and is not representative of what an high quality active pre-amp does when it does highs right. For me, highs done right, is like a star against a night sky. The sky is darker, the star stands out more sharply BUT is not, in itself, brighter. Does that make any sense to you?

In my experience with other units v passives the biggest difference can be in dynamics. As mentioned set up of a passive to compensate for IC impedence problems, etc, can make a big difference.

IMHO, you just need a better (not necessarily more expense) active pre-amp. Oh, BTW, if you decide to go with a passive be sure to do lots of research 1st. They are NOT all neutral, some are additive or subtractive.

I have been using a Reference Line Preeminance 1A passive preamp for the last two years. I find that recessed treble and listener fatigue comes primarily from poor recordings.

The passive to my ears lets everything through as recorded. It has meant that some CD's sit on the shelf because the recording values suck.

I am using the Adcom gfp-750 with two Classe Dr-15 amps (in bridged mode), Apogee Stage speakers, Marantz SA-1 SACD Player, Krell 300cd player, Herron MM phono stage with VPI Scoutmaster turntable. Cables have been Cardas Golden Reference (very low capacitance) and Nordost Quattro Fil. I've switched between both cables and haven't noticed much difference as it relates to treble extension. There was an online magazine review done which noticed the lack of transient decay when the Adcom was used passively. I suspect that's it's a feature of this preamp which can't be overcome regardless of which cables and components are used. Can anybody confirm this or had a similar complaint with the GFP-750?

I alternate between passive and active preamps and find that the difference is that usually described, active better dynamics, passive more transparency less coloration. But with good equipment the differences are not earthshaking. I am not absolutely positive that I could pass a blind test as to which was playing if I didn't have the other to compare. But one thing is clear, passive gives you more bang for the buck. In Martin Colloms testing the Creek 21 and 22 placed ahead or a lot of Krell, Audio Research, Conrad Johnson, etc active preamps. All this is contingent on your CD player having an output stage that will drive a power amp and a power amp with reasonable input sensitivity. My Meridian 605s only need .5 volts.

Contrary to Clio's advice, if you want to get the most out of a passive your best bet is to match the amp and source for input and output. IOW, the source output should be just barely able to drive the amp to full output.

This will mean that the passive is turned up all the way for full volume. The advantage of this is that passive controls traditionally limit dynamic contrasts and bass impact as you turn the volume down, due to the interaction between the cable, the input of the amp, and the control itself. So to minimize this you will want to set things up so that you are operating the passive at or near full volume.

A properly designed active line stage will be able to control the interconnect cable to a great degree, in fact that is one of the functions of the line section. If done right, the cable will cease to have any serious consequence regardless of its length or construction, but too many active line sections are designed without this in mind, hence a passive can give them a good run for the money. But if the active line stage is designed and built right, no passive made will challenge it.

Ralph,

That was not my experience using the S&B transformers. My setting was about 12 o'clock and it was fine in my system. My amp was .8V sensitivity with high gain and 67k input impedance.

I do agree in principle with what you are saying and the data in the S&B link I provided bears this out. However, it appears that the data also supports that the changes in impedance due to the volume control setting are not that big a deal and I would have to agree based on my experience.

Hi Clio09, with TVCs its a different game and in that context I agree with you. My comments apply only to passive volume controls that are transformerless.

A properly designed TVC can, IMO, do better than the best PVCs; in fact I think that unless you have the very best in an active line stage, that a good TVC is going to be one of the better if not best alternatives.

Lack of dynamics hasn't been my experience with any of the passives I've owned:

Promitheus TVC
Sonic Euphoria (autoformers)
Bent TVC (S&B trannies)

In all of these cases, dynamics seemed explosive, not lethargic. The presentation also seemed airier and more detailed than actives in the same price range. I've heard the new Bent passive with Dave Slagle's autoformers and would say the same thing.

I don't doubt the calculations show:

passive controls traditionally limit dynamic contrasts and bass impact as you turn the volume down, due to the interaction between the cable, the input of the amp, and the control itself

but in practice, these shortcomings were minimal or inaudible in my system. This was especially true of the Sonic Euphoria and Bent with autoformers. Low level listening with these passives was a pleasure. They had a fullness at low volumes that seemed more natural and proportional than an active.

However, a back-to-back comparison of the Bent TVC and an Audible Mod3a indicated something was missing in the midbass area. A friend and I both agreed that the Mod3a was noticeably warmer in a good way. After a year of intense interest in passives, I've returned to an active, but I still believe a good autoformer-based passive will outperform most actives in the sub 1000 category.

Ralph, glad we're on the same page with TVCs, although I trust your passive volume control option for the M-60s is well designed.

Mingles, my K&K TVC (S&Bs) outperformed my Cary SLP-98 ($3995) and Joule Electra LA-100 MkIII ($3750). I'd venture to say the Bent units in particular, either the S&B or Slagle models will outperform many preamps, both sub and over $1000.

Now Dave Slagle has come out with a manual DIY version using boards developed by John Chapman for a ridiculously low price. Just add a case and some RCAs and you're done. Even if you had someone build it for you it would still be a bargain.

See here:

http://www.audiogon.com/cgi-bin/cls.pl?preatran&1230319450&/Intact-Audio-Slagleformer-Modu

Mingles, sure sounds like your experience is similar to mine, but keep in mind also the caveat 'properly designed' which I am careful to use. IMO, most of the active line stage technology you see today seriously trails behind amplifier and phono preamp technologies. I feel that this is because many line stage designers are not even aware that control of the interconnect cable is one of the goals/functions of the line section.

Thanks Elizabeth for responding. I too feel that the GFP-750 is a fine preamp in passive mode and for the money is a bargain. My only serious complaint with the GFP-750 is better described in this excerpt from an online magazine review:
At various listening sessions, my son Marc, a trained musician for both trombone and guitar, (not an audiophile) would join me and add his input. One CD we listened to was Keith Jarrett’s At The Blue Note: Saturday, June 4, 1994, First Set (ECM1577 78118-21577-2). The trio was beautifully recorded and it became evident that what was missing was the air and extension in the high frequency range, which manifested itself on Jack DeJonette’s delicate and varied cymbal work. To paraphrase Marc, it was as if the decay of the cymbals was cut short. In the bypass mode, this was slight but noticeable and to a lesser degree with Keith Jarrett’s piano. The bass resolution, timbre, and resonance of Gary Peacock’s bass playing were right there with no apparent differences in achieving the full body of the instrument.

Through the Adcom, the dynamics of the piano and the full body of the instrument almost matched the direct feed, but that slight loss of full note decay or ambience was just barely noticeable. And I do mean barely. I feel this is still quite an achievement and more an act of omission than addition of coloration or artificiality. Consider also the fact that an additional set of interconnects and connectors are in the chain. This in itself will cause some losses to the sonic protrait.

Lornoah, I can't comment on the GFP-750, b/c I haven't heard it, but I'm fairly certain it doesn't use transformers or autoformers in passive mode. Potentiometers are the most common attenuator and it wouldn't surprise me if this is what the 750 uses. If this is the case, it would explain why you're hearing these shortcomings. A potentiometer can't preserve the impedance curve of the source when the volume is turned down. Ralph (Atmasphere) explains the technical details up above. But I do know that transformers and autoformers do a much better job at preserving the impedance, and this is why they sound better. You should be able to hear this difference in a resolving system. I certainly did when I compared a Creek OBH-10 (potentiometer-based) to a Bent TVC. The Creek was no match. The Bent had a more open sound and better frequency extension in both directions, but especially in the bass.

Does anyone know of a passive preamp that will provide me with this treble extension and at the same time sounds relaxed with no listener fatigue. Thanks.
Lornoah (Threads)

All of the passives I've owned had excellent frequency extension and no fatigue. There was no premature decay in the upper registers. They presented music with an abundance of air and detail.

If you want to stay with a passive, I recommend a Sonic Euphoria or a Promitheus TVC. They're both common in the classifieds and their tech design is more mature than the 750.

I forgot to mention Dave Slagle's latest DIY passive that Clio09 pointed out. It's based on the same autoformer that John Chapman uses in his current Bent line-up. I absolutely doubt you can do better for $350.

it's a mistake to think that a preamp is not additive or subtractive. since no components are perfect, all are additive and/or subtractive. the colorations of some may be more difficult to detect. after careful listening , i beleiev it is possible to determine the sonic personality of any component.

if you approach component selection with the idea that all have flaws, you will listen until you find that component which complements your sonic preference, without concern for accuracy.

I may have disovered the trouble. For the past two weeks I have been using my Krell 300cd player with single ended interconnects. Previously (for 6 years) I had been using it balanced. With a full-level 1kHz sinewave, the output from the 300cd is 4V from the balanced outputs, 2V from the unbalanced. I'm would say the output is too low unbalanced to make a satisfactory match with this passive preamp.