Passive Preamps: Jumping Ship

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.