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In the Forum: Audio Discussions
In the Thread: Passive transformer based preamp
Post Subject: Re: Thorsten's preamp ideaPosted by Thorsten on: 11/8/2005

cipro

cipro click
Roman,

 Romy the Cat wrote:
May I ask you, this realization of yours… dose it has any “sound”.


The one we have build which is a little different (6S45 not C3g, also tried WE 417A, 437A, TX-101 Copper not silver, AN UK Line Output Transformer as anode load choke, CLCLC Supply, valve rectified, not regulated) has very little sound, but it does have some "tube sound" and hence the use of the silver TVC over Copper. It is not as transparent as the simple passive, it seems a little more compressed too and seems to blow up stereo images a little, but it is fairly little there.

The reason my friend uses this is that he needs the gain and load drive for his passive LCR line level crossovers and equalisers and uses very low gain Amplifiers on top of that (6SN7 drives 2A3 or 300B in single stage differential).

 Romy the Cat wrote:
You see, I have my “feeling” that it is hardly possible to make any tube-based completely transparent line-level buffer.


You may be right. The point is that it is not a "buffer", but a preamplifern with gain for applications where gain and exceptional load drive ability is needed and passive cannot go. In other words, it does not compete against "transparent buffers" but against other active preamps with gain.

 Romy the Cat wrote:
Anyhow did you look at the SS world for the “ultimate buffers”?

Best buffer in production I know is BUF634, out of production BUF03 immediatly followed by a complementary FET PP Buffer (same as Curl is fond of using). They are not completely transparent either and need a really good powersupply as well.

BTW, here the schematic for our preamp, signal section in principle, parts choices see previous msg, other suppliers for similar parts exist:

Preamp Schema.jpg

Ciao T

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