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In the Forum: Analog Playback
In the Thread: Where are our good phonostages?
Post Subject: Re: Thorsten's LCR - I don't get it & more on high Gm wondertubesPosted by cv on: 10/3/2004
Hmmm - the whole LCR thing, I don't like the idea.
I'll admit to having no experience of it, but in engineering terms, it just gives you a constant impedance filter. The EQ is still done by caps essentially, far as I can tell. I see the whole setup as inferior to a low Z split RC network with top quality caps (look at the size of the required caps in the 600 ohm LCR for instance). Ok, so as the tubes age, the constant impedance is nice, but there are ways around that with other schemes.
Now, an LR network is another matter... Stevens-Billington have now released a 10k version - I say, get the inductors (which must have been quite carefully optimised to maintain a constant L with frequency) and use them in an LR network...
As for high Gm, check out the WE416 and the 7768:
http://hereford.ampr.org/cgi-bin/tube?tube=7768
The thing to watch with triode input stages (if not cascoded) is that they have a high input capacitance. Not a problem with MC cartridges, but if you are driving them from a transformer, it might be.
Just a few random thoughts for yous there.
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