5751

5751's are a slightly lower gain version of the 12AX7. They can be used anywhere a 12AX7 would be used. They have a nice smooth/mellow top end and are sometimes favored over 12AX7s in guitar amps and audiophile equipment. A common guitar amp application is situations where humbucker pickup equipped guitars sound harsh. Using a 5751 if the first gain stage (V1 or V2) will often tame this harshness.