The drive requirements of the OP stage are not as critical as mentioned in earlier posts. The KT88, EL34 & 6550 all have G about double that found in the original Mullard circuits where we find 6L6, 5881, Etc.
A single dominant pole is a safe way to go in this cct. There are a couple of worked samples in RDH4 worth looking at.
Also strongly recommended by none other then Norman Crowhurst. You can read about how to implement all in a couple of his articles.
I like the cct proposed by Alex Pogossov recently. The attachment shows how it is connected in an SE Amp. The frequency selective network is in the cathode of the first stage rather than between stages.
My opinion, anyway, having done it.
Cheers, John Stewart
PS- The bicycle went more than 1000 KM in August (622 miles). Pedalling again today. Hey Patrick, hows it going in OZ? J
|