Typically you can use 5751s where 12ax7s are called for. The 5751s having less gain just gives your volume control a little more flexibility, ie you can turn your volume control without a little adjustment giving you a big volume increase as 12ax7s give in some applications. With my preamp there is a noticable difference in gain between these two tubes. 5751s were speced for the military and are very rugged. They also sound very nice, IMHO. I too like their air and detail and I would add bass response. Just to make sure, send altavista an email, they are the experts on Counterpoint equipment.
12AX7 vs. 5751
I'm getting my first tube pre (Counterpoint 7.1) this week or early next week, and of course I have start fiddling with it ;-) I've been reading Joe's Tube Lore (http://www.audioasylum.com/audio/faq/joes-tubes.html) and the 5751 caught my eye, however I see statements like "lower gain that the 12AX7" and lower "mu" (what is mu?). Anyways could I use the 5751 tubes in my Counterpoint without causing any damage? altavistaaudio.com mentions nothing about the 5751.
thanks
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