Evanc and Einric, you guys used a 230v xformer; but the manual seems to be recommending 300v for my tubes. Is this what I'd want?
Antek - AS-2T300
Antek - AS-2T300
Dont rule this one out...I used this on my Tetra Phono stage and if you are using SS rectification as the all in one kits or using a PS1 or PS3 this is an inexpensive good little unit
ALLIED 6K88VG
ALLIED 6K88VG
Right, typo on my part. I meant 2A fuse. Nice little transformer, but I already have the torodial ordered.
I see many recommendations for this pot: RK27112A00AK ALPS Potentiometers
The trick is, it's a 9mm diameter shaft, and I'm not finding many knobs that fit. I'm not sure of the differences between that one and this:
RK27112A-S20-C1-MN104 ALPS Potentiometers
I see many recommendations for this pot: RK27112A00AK ALPS Potentiometers
The trick is, it's a 9mm diameter shaft, and I'm not finding many knobs that fit. I'm not sure of the differences between that one and this:
RK27112A-S20-C1-MN104 ALPS Potentiometers
This is the one I have used on a couple preamps I like it because it has the slotted shaft so the set screw on the knob holds better.
Here is the knob I use
Here is the knob I use
Let me see if I understand how to calculate R12a and R12b.
On page 8 it says 6CG7 tubes will draw 2.6mA. Together that's 5.2mA per channel, or 10.2mA total. (I'm using four 6CG7's)
My transfo is 230vac, so 230X1.414=325.22, minus 2v for rectifier loss. So the transfo once rectified will deliver 323.22vdc. So I need to drop the voltage by 23.22vdc. According to the chart in the manual, R12a would be 3,000 and R12b would be 10,000.
Can you guys double check my figures here?
On page 8 it says 6CG7 tubes will draw 2.6mA. Together that's 5.2mA per channel, or 10.2mA total. (I'm using four 6CG7's)
My transfo is 230vac, so 230X1.414=325.22, minus 2v for rectifier loss. So the transfo once rectified will deliver 323.22vdc. So I need to drop the voltage by 23.22vdc. According to the chart in the manual, R12a would be 3,000 and R12b would be 10,000.
Can you guys double check my figures here?
OK...well first it is not more voltage, it is more CURRENT.
Now as to the technical piece, not sure how to put it other than tubes have sweet spots of sounding the best and passing along/amplifying the cleanest signal.
What I can say is I have played quite a bit with operating currents in my 9 pin aikido and my personal preference is that the amp sounds better to me with the tubes running hotter (more current). Downside becomes shorter tube life but in the grand scheme I am not running $$$ NOS tubes where I might second guess this approach.
Now as to the technical piece, not sure how to put it other than tubes have sweet spots of sounding the best and passing along/amplifying the cleanest signal.
What I can say is I have played quite a bit with operating currents in my 9 pin aikido and my personal preference is that the amp sounds better to me with the tubes running hotter (more current). Downside becomes shorter tube life but in the grand scheme I am not running $$$ NOS tubes where I might second guess this approach.
Yes, R17 and R18 create the voltage divider to create your B+/4 for heater reference.
Typical you would use the 300K / 100K combination. So think about it. If the series of R17 and R18 offers 400K of resistance right? You have 300V going into the circuit which ends at ground. So, under 300K resistor and above the 100K resistor you will have dropped 75% of the voltage right? Thus...the tap creates your B+/4....
Typical you would use the 300K / 100K combination. So think about it. If the series of R17 and R18 offers 400K of resistance right? You have 300V going into the circuit which ends at ground. So, under 300K resistor and above the 100K resistor you will have dropped 75% of the voltage right? Thus...the tap creates your B+/4....
I've been reading some of Broskie's blog posts and (I can't find the link right now) he mentioned using more plate current for the input tube vs the output... I remember giving examples of 300r for the input tube Rk and 1k for the output tube Rk on a 6SN7/6CG7. He said it would cause the tubes to age at different rates and said the input and output tubes could be changed to even out wear.
Is there a good reason to run the input and output tubes at different plate currents?
Is there a good reason to run the input and output tubes at different plate currents?
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