Finished my Rocket and it is amazing. I did notice that it is a litter dirtier than some of the others I have heard. I did not use the normal PT I had a NOS Thordarson (540CT @260mA). When comparing my voltages to chart in the "FILES" section my voltages are a little high about 35-40VDC. I attached my calculation sheet for reference.
I have not installed my final power tubes yet so the numbers might change a little.
In my mind I have two choices, as I was planning to install a VVR do I:
1) Install the VVR and use a resistor to hold it just below full at WOT.
2) Install a zener diode or two on the CT of the pt to drop my voltage there?
Any thoughts?
Rocket Voltages
Moderators: pompeiisneaks, Colossal
Rocket Voltages
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Last edited by jon on Wed May 11, 2011 1:01 pm, edited 1 time in total.
Re: Rocket Voltages
You will probably lose maybe 15V on the B+ with power tubes installed. Depending on the power tubes, they might handle the resulting B+ or might not. Both your solutions are realistic.
Re: Rocket Voltages
You will not gain any headroom by dropping voltage - it goes the other way.jon wrote:Finished my Rocket and it is amazing. I did notice that it is a litter dirtier than some of the others I have heard. I did not use the normal PT I had a NOS Thordarson (540CT @160mA). When comparing my voltages to chart in the "FILES" section my voltages are a little high about 35-40VDC.
Re: Rocket Voltages
If it remains too dirty for your taste either change out V1 to 12AY7 or 12AU7. Or you can reduce the V1 Plate 220K resistor to 200k or 180k or 150k for more headroom before gain kicks in.
Mark
Mark
Re: Rocket Voltages
I installed a VVR onto the rocket today. Using a 220K resistor feeding the 1M pot I was able to hold the voltage from going WOT. The amp sounds great thanks guys.
Re: Rocket Voltages
"WOT"???jon wrote:I installed a VVR onto the rocket today. Using a 220K resistor feeding the 1M pot I was able to hold the voltage from going WOT. The amp sounds great thanks guys.
Did it increase the headroom that you reported lacking in your first post?
Enjoy!
Re: Rocket Voltages
The amp has a little less punch but pickup'd the singing quality that I was looking for.
Re: Rocket Voltages
Once you dial in the sweet spot, would you measure and post the voltages?
Thanks!
Thanks!