clintrubber said:W.r.t. broadcast-specs, I can understand, but more from the BBC-label than neccesarily from this circuit-topology, which is actually not that unlike as used by many other brands (I figure those octal Altec-micpre-plugs won't be considered broadcast-quality). But the devil is in the detail of course, I'm not saying that 'quite alike' topologies sound the same.
I totally agree, Peter. The main thing which I think makes these modules (and all the others which are used) stand out is the quality transformers.
Davo said:So if I were to use the Lundahl ll1530... configured @ 1:7 (200:10K)..... is that too much of a jump in turns ratio?....
I'm thinking in terms of "gain" w/ the turns ratios.... whereas I should probably be thinking just in terms of matching impedances
between source and load, as you stated.
Well, what's going to happen here is, the secondary is going to be connected to the same impedance in this circuit as if you had used a 1:3.5 model. So what will happen is, with a 1:7 transformer, the input impedance is going to be four times smaller (difference in turns ratio squared). A quick glimpse at the schematic and I'd guesstimate the unit has ~2K input impedance. Four times less at 500R doesn't sound like a great idea to me. You might get away ok with say 1:5 though if you are really struggling to find suitable models.
so is 10k too far off from 8k (on the input tx,s secondary) to be usable in this instance?
Remember you quoted the 1:3.5 as 600:8K...... Well, that would actually be 200:2.5K if you are talking with respect to what it does to a 200 Ohm source.
Roddy