separks wrote:Soren, if you want to use a LTP and have below 400V to work with, then definitely try using the LM234Z/LM334Z. Use the 'B' tab in TubeCAD and ignore the Rk and the B- VDC. You will need to size the current set resistor to make sure there's at least a 7V to 15V drop across the LM234Z, but otherwise, Tube CAD can help you sort this voltage swing out. To size the current set resistor, just look at the plate voltage and check out the tube curves in the datasheet. Hope all this makes sense. You can have a LTP at those low voltages, but you'll need some tiny help from silicon. Oh, you'll also need to AC couple this stage.
sorenj07 wrote: Do you really think it'd be OK to drop a driver stage, by the way? I love the idea from a simplicity point of view but would it sacrifice headroom or something?
sorenj07 wrote:One other thing - what does the "balance %" statistic mean?
sorenj07 wrote:p.s. where does the voltage of 380 come from? my B+ can only be 280 or so. or are you suggesting a separate little power transformer for the 12BH7's?
separks wrote:I forget if you rebuilt your linestage or did another from the ground up, but with a linestage and no negative feedback loss, I think why not? My 6B4G SET is around 16dB of overall gain.
[/quote]separks wrote:I initially swagged the CCS could gain you 100V - ie, 100V is not being watsed in a longtail. In reality, you are saving 50.7V (ie the grid voltage in ours will be 0V). This needs simulation needs a little reworking, but it shows what I'm talking about. Adjust it until the extra B+ V and the grid voltage are the same.
sorenj07 wrote:I'll get on that but I'm still a bit confused as to where the 100V are coming from, seeing as my power transformer will probably be something like 300 or 325V into a choke input, and then there would be another RC or LC filter after the main LC for the OPT... How can I "save" voltage that was never there in the first place? Does the CCS actually up the whole voltage?
The 280V is _before_ waste in a longtail, and before the plate load resistors, right?
sorenj07 wrote:Update! I'm probably going to use a 50VA, 9V toroidal power transformer as my OPT. The dual 115V primaries will act as a centertapped primary, and using 9V secondaries in parallel should yield me an impedance ratio of ~1306:8 ohms, which is perfect for the very low plate resistance of the 6S19P. I have no funds though so this is on the back burner :)
separks wrote:Did you cull this idea from a website in particular? If so, please link it. Interestings.
BTW, sorry your 6EM7 care package hasn't been sent yet - it will!
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