burnedfingers said:
As I noted above, with 1uF on the PSU board I see 247V j(252+ with 2uF). Any suggestions for the cap? Is a cap needed?
Probably very basic questions but I'm quite new to tubes.
I can see what PSUD models, but my obervations are about 25V over what PSUD predicts (PSUDII actually).
Thanks,
Steve
Quote:
I can see what PSUD models, but my obervations are about 25V over what PSUD predicts (PSUDII actually).
I came up with a different B+ also when I was getting my Aikido running (Bas boards) and I just calculated the voltage drop needed and changed the resistor values on the board.
I can see what PSUD models, but my obervations are about 25V over what PSUD predicts (PSUDII actually).
I came up with a different B+ also when I was getting my Aikido running (Bas boards) and I just calculated the voltage drop needed and changed the resistor values on the board.
Voltages
It would seem a "first" resistor in the PSU of about 1.5k will give me ~220V. I made a 1.36k from two 680R resistors and measured some voltages.
Here are they are:
B+ after ~ 5sec is 235; after > 1min 225V.
"Left" channel 6n1P
pin 1 ~113V to grd (seems to be stable with time)
pin 6~B+
430R to grd 2.1V (decreases slowly with time;eg, 1.87V @~2min))
"Left" channel 5687
pin 1 ~113V (also seems stable with time)
430R to grd 5.1V (increases slowly with time; eg, 6.1V @~2min)
"Right" channel 6n1p
pin 1 ~113 initially but decreases with time (eg, 85V @~2min)
pin 6~B+
430R to grd 2.5 initially but gradually rises (2.61V)
"Right" channel 5687
pin1 to ground initially ~113 but decreases matching 6n1p
430R to grd 5.6V but gradually increases with time (8.21V)
I have the following jumpers installed on both boards:
J1, J4, J6, J7. The heaters are wired as per instructions.
What could be causing my voltages to change with time?
Thanks,
Steve
It would seem a "first" resistor in the PSU of about 1.5k will give me ~220V. I made a 1.36k from two 680R resistors and measured some voltages.
Here are they are:
B+ after ~ 5sec is 235; after > 1min 225V.
"Left" channel 6n1P
pin 1 ~113V to grd (seems to be stable with time)
pin 6~B+
430R to grd 2.1V (decreases slowly with time;eg, 1.87V @~2min))
"Left" channel 5687
pin 1 ~113V (also seems stable with time)
430R to grd 5.1V (increases slowly with time; eg, 6.1V @~2min)
"Right" channel 6n1p
pin 1 ~113 initially but decreases with time (eg, 85V @~2min)
pin 6~B+
430R to grd 2.5 initially but gradually rises (2.61V)
"Right" channel 5687
pin1 to ground initially ~113 but decreases matching 6n1p
430R to grd 5.6V but gradually increases with time (8.21V)
I have the following jumpers installed on both boards:
J1, J4, J6, J7. The heaters are wired as per instructions.
What could be causing my voltages to change with time?
Thanks,
Steve
It looks like yout cathode voltage changed a slight bit after warm up and to me this looks normal. As the tube warms up it conducts and the voltage changes slightly. My (Bas board) Aikido will do the same thing. My voltages are the same as yours.
If you have changed to different 6N1p tubes you will find that the voltage will change slightly also. It will change slightly from tube to tube.
I have about a dozen 6N1P tubes and each one will give me a different reading.
You have 6N1P in both locations?
If you have changed to different 6N1p tubes you will find that the voltage will change slightly also. It will change slightly from tube to tube.
I have about a dozen 6N1P tubes and each one will give me a different reading.
You have 6N1P in both locations?
maynardg is correct. Switch to a 6CG7 or a 6FQ7 and its a step up
and you won't go back to the 6N1P again.
Mine runs 6FQ7's and 5687's(second tube)
and you won't go back to the 6N1P again.
Mine runs 6FQ7's and 5687's(second tube)
Oh yes. On the 6cg7, pin 9 is an internal shield and should be grounded. On the 6n1p, pin 9 is not used.
burnedfingers said:
No, I have 6N1P as tube 1 and 5687 as tube 2 for both channels. I don't know if these voltages continue to drop or if they level off. Not having tremendous tube experience (electronics for that matter) I thought I'd be a little cautious.
All components check out as correct so perhaps I'll power it up and measure after a longer period of time.
Thanks,
Steve
I rechecked PSUDII for the "expected" B+ since I had simulated with some incorrect data. With the 1.36k resistor the corrected simulation gives a B+ of 190V (it looks like the 1k resistor from the original BOM is spot on).
It would appear that it takes a few minutes rather than seconds for the voltages to stabilize (sp?). The interesting (puzzling) thing is that (I am using a single supply not dual mono) the B+ for one channel settles in at 177-8V (R) while the other at 188-90V(L).
Here is what I see now:
6N1P (L/R voltages)
pin 1 76.1/90.3
pin 6 181/173
430R 2.18/1.51
pin 8 78.5/91.4
5687 (L/R)
pin 1 72.4/78.2
430R 8.19/13.4
I think I'll put the original 1k PSU resistor back in place (I don't remember seeing such a difference in L vs R B+ originally).
I would assume I should wait until the B+ voltage settles down before measuring the rest. BTW, are the voltages I measured within the expected range (ie, are they normal)?
Steve
It would appear that it takes a few minutes rather than seconds for the voltages to stabilize (sp?). The interesting (puzzling) thing is that (I am using a single supply not dual mono) the B+ for one channel settles in at 177-8V (R) while the other at 188-90V(L).
Here is what I see now:
6N1P (L/R voltages)
pin 1 76.1/90.3
pin 6 181/173
430R 2.18/1.51
pin 8 78.5/91.4
5687 (L/R)
pin 1 72.4/78.2
430R 8.19/13.4
I think I'll put the original 1k PSU resistor back in place (I don't remember seeing such a difference in L vs R B+ originally).
I would assume I should wait until the B+ voltage settles down before measuring the rest. BTW, are the voltages I measured within the expected range (ie, are they normal)?
Steve
quote:
The interesting (puzzling) thing is that (I am using a single supply not dual mono) the B+ for one channel settles in at 177-8V (R) while the other at 188-90V(L).
Well, there is a difference in tubes. One may draw more than another one does therefore the difference in voltage. There is roughly a 10 volt difference between channels. If you take tubes from channel A and put them in channel B you will see the voltage difference follow those tubes.
The interesting (puzzling) thing is that (I am using a single supply not dual mono) the B+ for one channel settles in at 177-8V (R) while the other at 188-90V(L).
Well, there is a difference in tubes. One may draw more than another one does therefore the difference in voltage. There is roughly a 10 volt difference between channels. If you take tubes from channel A and put them in channel B you will see the voltage difference follow those tubes.
On all datasheets I have seen for the 6N1P, pin 9 is a shield between the 2 triode halves as well.
Regards,
Bas
Quote:
On all datasheets I have seen for the 6N1P, pin 9 is a shield between the 2 triode halves as well.
Yup
On all datasheets I have seen for the 6N1P, pin 9 is a shield between the 2 triode halves as well.
Yup
I bought 2 sets of boards from Bas. I stuffed the second set with parts sourced from Digikey (other boards have a few RS resistors). In this set I thought I'd try the 6N1P for position 1 and ECC99 for position 2.
I used the same power supply as for the 6N1P/5687 combination. I see the following voltages:
B+ channel1 266
B+ channel 2 267
channel 1 R3 (2.75V); R8 (3.83V)
channel 2 R3 (2.76V); R8 (4.69)
The B+ came up to ~260V fairly rapidly (after a few seconds delay upon powerup) and settled in at the values above (and were steady). The other voltages were pretty steady also. Is the 2.75V vs 1.2-5 V something to worry about?
Steve
I used the same power supply as for the 6N1P/5687 combination. I see the following voltages:
B+ channel1 266
B+ channel 2 267
channel 1 R3 (2.75V); R8 (3.83V)
channel 2 R3 (2.76V); R8 (4.69)
The B+ came up to ~260V fairly rapidly (after a few seconds delay upon powerup) and settled in at the values above (and were steady). The other voltages were pretty steady also. Is the 2.75V vs 1.2-5 V something to worry about?
Steve
SteveA
How does it sound?
You might play with B+ voltages to see if the sound gets better.
Maybe someone else can comment?
How does it sound?
You might play with B+ voltages to see if the sound gets better.
Maybe someone else can comment?
burnedfingers said:
I haven't hooked it up for sound yet, but I will for this combination. I want to lower the B+ a bit and then I'll check out the sound.
It's not clear to me why the 6N1P/5687, with the same PSU, gave such bizarre behavior. I would really like some comment on my voltage observations with this setup. Why does the B+ start at 240+ and then decrease to 170-180. Is this normal and expected?
Steve
Hi Steve,
This is normal. Perfectly normal.🙂 and expected..if it all takes place within the first minute of starting up that is.
What is happening is that the tubes 6n1p/5687 are warming up. As they warm up they actually start working. I.e. current starts flowing.
Because the current starts flowing...the current through the voltage dropping resistors starts becoming bigger.
The bigger the current through the voltage dropping resistor...
the bigger the voltage across the resistors...
in other words..the more current through the resistor..the more voltage it drops.
(A resistor is in a circuit a current to voltage converter)
Hence the use of a resistor for instance as a plate resistor...converting the alternating current of the tube...to the alternating voltage that is your output signal...
Regards,
Bas
"Here is what I see now:
6N1P (L/R voltages)
pin 1 76.1/90.3
pin 6 181/173
430R 2.18/1.51
pin 8 78.5/91.4
5687 (L/R)
pin 1 72.4/78.2
430R 8.19/13.4"
Bas-
Thanks for the comments. The above quote contains the voltage measurement I found for the 6n1p/5687 combination. Can you comment on these (normal or not) in light of the ~180V B+?
Also, with the 6N1P/ECC99 combination the B+ "behavior" was quite different (ie, it rapidly rose to 260 and settled in at ~265V). Is this the difference one should see with 5687 in position 2 vs ECC99 in position 2?
Thanks again,
Steve
6N1P (L/R voltages)
pin 1 76.1/90.3
pin 6 181/173
430R 2.18/1.51
pin 8 78.5/91.4
5687 (L/R)
pin 1 72.4/78.2
430R 8.19/13.4"
Bas-
Thanks for the comments. The above quote contains the voltage measurement I found for the 6n1p/5687 combination. Can you comment on these (normal or not) in light of the ~180V B+?
Also, with the 6N1P/ECC99 combination the B+ "behavior" was quite different (ie, it rapidly rose to 260 and settled in at ~265V). Is this the difference one should see with 5687 in position 2 vs ECC99 in position 2?
Thanks again,
Steve
I would have expected generally the same behaviour as with the 6N1P and 5687 combo. So it is a little odd. I'm guessing that the ECC99 draws less current with the given resistance.
It is not what I would suspect...but I suspect it is working.
On pin 1 of the left 6n1p I would expect to see 90.5VDC.
On pin 1 of the left 6n1p I would expect to see 86.5VDC.
The differences between the voltages across the 430 resistor are a trifle on the big side.
pin 8 should be the exact same voltage as pin 1 as they are connected. (the differences of around 2 volt makes me doubt your multimeter....or maybe the voltage had not stabilized yet.....i.e. time between measurements caused the discrepancy)
5687 (L/R)
pin 1 72.4/78.2
430R 8.19/13.4"
again on pin 1 I would expect to see roughly half of b+...see pin1 on the 6n1p.
again the only worry is the relatively large difference between the voltage of the cathodes....
To make a long story short..AFAIAC you should connect her up to a little speaker...and see how she blows.