[HD-5000]

Whats wrong with transformer based preamps? I mean, if you want the ultimate performance....

 

[eric343]

Yes, I've heard transformer preamps were the ULTIMATE... but I've always assumed they were quite expensive. So expensive that I'd totally forgotten about them until this thread

 

[BoyElroy]

I looked into using Jensen transformers to couple my balanced preamp to my single-ended amp a while back. After doing some reading and head scratching, I still couldn't figure out why so many people thought this was such a great idea. I mean, if your amp is fairly close to your preamp and you have a fairly high output source signal, wouldn't the simplest and purest method of attenuation be to use 2 resistors in the signal path a la a stepped attenuator? The idea of using the electric field interaction between two windings to control attenuation somehow seems inherently inaccurate to me. What advantages would a transformer preamp have over a high quality dual mono stepped attenuator unit?

 

[wallijonn]

has anyone ever made one of these: "Aunt Corey's Homemade Buffered Passive Preamplifier" http://www.stereophile.com/showarchives.cgi?54:0

it does sound interiguing. and the notes about being a tweaker were a riot.

i'm just starting my research guys. so if you could include prices I'd much appreciated.

I will be getting my sm70 in afew days. and i want to set up my system right. obviously i need all the help i can get.

i'd like to break open my cd player and put a volume control before the op amp (at it's input stage).

anyone know of a good source for Alps Blue or Black Beauty pots?

 

[KurtW]

I have the Welborne labs Revelle passive preamp and can highly recommend it. It has dual stepped attenuators and is overall a very high quality piece of gear.

 

[wallijonn]

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

 

[gdahl]

If the other elements in the system provide a suitable environment (impedance relationships and gain structure), a transformer-based passive attenuator (using, for example, the Stevens & Billington TX-102) can provide fabulous results. I would go so far as to say it is the ultimate, in my experience. Caveat: in my system, I made certain that the gain structure and impedance relationships were suitable for a transformer volume control (TVC).

If this isn't practical in a particular system, the next step down is to use an active stage with a high quality resistive attenuator. A "passive preamp" using a resistive attenuator doesn't really provide the same sonic potential. The problem is caused by a relatively high output impedance at typical volume control settings. The typical result is decreased dynamics, HF extension, and increased coloration from the interconnect between the passive preamp and amp.

Is the potential sonic improvement elimination of a stage outweighed by the sonic penalty of a passive preamp's problems? In my experience, yes. Of course, this assumes that one uses a really good stage, and of course, a really good attenuator.

The best use of a "passive preamp" approach, as far as I am concerned, would result from locating the attenuator within the amp itself, minimizing the physical distance between the wiper and the input terminal of the amp's first amplifying device. But even there, I'd use a TVC if possible.

I have a financial (business) interest in a certain brand of passive stepped attenuator, but I use a TVC in my "ultimate" system because it is better still.

 

[Audio-Me]

I've decided to just have a passive output added to my next amp (gilmore dynamic), with a stepped attenuator for volume control. So it would still go through the input part, but bypass the gain stage. I'm looking forward to A/Bing active vs passive.

 

[wallijonn]

http://www3.sympatico.ca/r.godmaire/...eamplifier.htm

http://www.soundstage.com/articles/pete02.htm