Passive Preamps: Jumping Ship

Good for you Derek. I know that you've made more than your fair share of purchases trying to get there : )

I tried a few different passives and always thought that the signal lacked warmth, body, dynamics, slam, etc... Sure, the midrange was "see through" but the rest of it just did not draw me in. It was if the music itself had become "passive" and no longer "actively" interested me. I guess that's why they say that audio systems truly are "personal preference" and "synergy" based... Sean
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Oh how I've wanted passive preamps to sound better than active preamps in my system, especially when I had a sweet tube preamp that unfortunately used up tubes. I've stuck with the actives for exactly the reasons you mention.

I have always wondered why some listeners like passive preamps. I never understood the significance of these since they offered no sonic benefits that I could detect. Glad other listeners are hearing the difference that a good active preamp offers

Hmmm, since there is no one here defending passive attenuators, I think I'll have to chime in with my $0.02. I came in the exact opposite direction from Justlisten- I started with expensive tube preamps (BAT, CAT, Thor), and while each had certain alluring qualities, none of these (nor any other active I've had the chance to demo, including Lamm and ML) match the transparency, neutrality, freedom from noise/grunge, and low level resolution that a high quality passive provides, so long as your system is geared for a passive. More often than not, in my experience, those people that I have known who had problems with passives were either suffering from impedance mismatches, poor output stages in their source components, insensitive amplifiers (almost no solid state amplifiers work with passives, guys), or overly capacitive cables - in that order of frequency. In particular, the first two problems are the ones most responsible for the loss of dynamics that some experience when trying a passive in their system. Unfortunately, I have found that most manufacturers of passive attenautors are not as up front as they should be in describing the limited applications for their products.

I'll join Rzado, just to get the numbers pro and con in a bit better balance. I agree with all he's said. But if anyone is considering buying a passive, there are a number of things to check out. A look at www.goldpt.com, and its DIY section in particular, is a place to start. I've gone with DIY passives myself, and don't think it's easy to beat a good one for any amount of money spent on a commercial product. Just get world-class switches (like Shallco) for ladder type stepped attenuators, dual mono to get the effect of a balance control that costs nothing in circuit complexity, and good resistors, connectors, internal wire, kept as short as you can manage. I left a CAT SL-1 III, with its signal path simplified at the factory, for my own DIY passive, and have never looked back. I get the "magic of tubes" in my power amps, and while I wouldn't do without it, I don't think one needs it further up the line.

I normally use my tube preamp with my CJ Premier 11a tube amp but I also own an Adcom GFP-750. The Adcom sounds life less in passive mode compared to active. I suppose system matching must be very precise for a passive preamp to sound decent. ???

I was using the anlogue outputs of my Theta Miles cd player (balanced upgrade) for the past year or so, and just finally splurged to get a preamp for my system (a BAt vk-31). Your discription parallels mine. More presence, more fullness, more depth (increased bass?), the notes for example on some Maria Callas that I use as a reference much more "there" and rich.

I haven't noticed the lack of transparancey because I've been so taken by the increase in body and presence. There might be a few less creaks and whispers, but it is more than made up for the increase in growls and moans (? that make sense?)

pcanis

When customers ask, I tell them passive attenuators are like kissing thre most beautiful woman in the world....

But she keeps her lips tight.

So guys go back and forth...seeking more romance. A preamp is there to add color. You certainly don't need one to cut the gain of your CD layer in half.

I've had many pre-amps both passive and active. I've always found that the circuitry in active pre-amps causes colorations, as stated above by Kevin from Upscale Audio. Sometimes this is a good thing, as in the case of the Wyetech Opal. Sometimes not. I would prefer transparency in my system to any colorations.

The active circuitry in active pre-amps is also subtractive in detail as well as transparency. I have to laugh at reviewers who say that the active pre-amp they are reviewing has "no sound at all". How would they know? They are only comparing it to the pre-amp already in their system. Reviewers who fairly review pre-amps have some type of DAC or source with a volume control that let's them test the credibility of the "no sound at all" statement. I have never seen any reviewer using this technique make that statement, and the conclusion they ultimately make is that they prefer the system without the active pre-amp.

Passives are more transparent, but inevitably limit dynamics and bass. I have found two solutions. The first is the RDP-1 from Z-Systems. It is a digital pre-amp that goes between your transport and DAC, and controls volume in the digital domain. It is also a digital equalizer. The second is the Silver Rock passive from the Swiss company Audio Consulting. It is a completely silver wired transformer/potentiometer with dual mono construction. Neither of these pre-amps limits dynamics or bass, and the transparency is stunning. TAS reviewed the Silver Rock a few months ago, and compared it to some very high-end active pre-amps. The actives were less transparent, and were grainy in the mids and highs when compared to the Silver Rock. They also commented positively on the Silver Rock when they reviewed the Halcro amps.

The Silver Rock sometimes causes grounding problems when put in your system, and is a bit finicky about other equipment. It also isn't the most beautiful piece of equipment around, has no remote control, and is very expensive for a passive. Although I would add that, judged solely on sound quality, it's a bargain.

Both are wonderful solutions to volume control in a CD only system. I have both at the moment, and will sell one in the near future after I decide which I like the best.