Thanks for the comment Andy.
Yes, the second and third amplification stages on this set are carried out by each side of an ECC85 (V7 on the circuit). This circuit is similar to later versions of the WVB although all the earlier ones used EF86 AF pentodes throughout.
I have noticed that Vortexion revised the circuit of these three-head machines with ‘B’ off-tape, monitoring over the life of the model. This one that I have has a transformer in the ‘monitor’ output but other (earlier?) versions have a directly wired socket in the cathode circuit of V7 o/p side.
Another ‘oddity’ of the CBL is that it has two separate bias and erase oscillators which I thought might cause cross-talk problems at the heads. However it looks like the makers took some trouble to ‘tune’ the oscillators to run at the same frequency by capacitor selection. Both run at 64kHz.
For a change from valves I’ve got a Ferrograph Series 7 quarter-track on the bench now and am trying to figure out why it records at a lower level one one track than the other.
Bill
Yes, the second and third amplification stages on this set are carried out by each side of an ECC85 (V7 on the circuit). This circuit is similar to later versions of the WVB although all the earlier ones used EF86 AF pentodes throughout.
I have noticed that Vortexion revised the circuit of these three-head machines with ‘B’ off-tape, monitoring over the life of the model. This one that I have has a transformer in the ‘monitor’ output but other (earlier?) versions have a directly wired socket in the cathode circuit of V7 o/p side.
Another ‘oddity’ of the CBL is that it has two separate bias and erase oscillators which I thought might cause cross-talk problems at the heads. However it looks like the makers took some trouble to ‘tune’ the oscillators to run at the same frequency by capacitor selection. Both run at 64kHz.
For a change from valves I’ve got a Ferrograph Series 7 quarter-track on the bench now and am trying to figure out why it records at a lower level one one track than the other.
Bill
