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LME49811 front-end for Gilmore amp?
I was all set to start gathering the parts for the Gilmore headphone amp, when a little research showed that acquireing the dual-matched JFET's, (2SK389/2SJ109), might be harder than I expected. (Amazing amount of drama surrounding those parts.)
So, can I use the new LME49811 chip to replace the front-end of the class A output section? Kinda like this: http://www.neighborhost.com/DIY/LME-Gilmore.png Will the 9ma max output of the 49811 be sufficient to drive the pre-drivers? I realize that the output-stage gain is less than unity, so the chip will need to run from a higher voltage. Just not sure if its this simple. Thanks all. |
Anyone? :)
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Have you deliberately swapped the drivers?
You can replace the 389/109 pairs with 170/74 discretes. Buy matched pairs or match them yourself and then thermally couple the pairs. Cin>=1.4 * Ci * Ri+Rs / Rin >= 1.4 * 10 * 57k8 / 1k8 >=450uF Ci could be reduced to 1u5F or 2u2F and still pass sufficient bass. Cin @ 10uF will kill the bass response. |
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I like the idea of using the 170/74 subs, but I thought those were discontinued also. Thanks for the input cap info. I'll see if I can locate the 170/74 subs. |
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When using LME49811, I don't think you need the discrete gain stage, just emitter followers, double emitter followers, CFP or something like that. |
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Thanks again guys. (Gals?)
I guess this just brings me back to the idea that I should just build it as it is, before I go messing around with "mods" that I'm not sure of. ;) |
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