Choky,
The music continus singing for 3 ~ 5 seconds. The main power supply contains 330uf. But I use a Bleeder with 100k.
I have shorted the Input to the principal GND of the circuit and the HMMM continues.
The HMMM kill when I power off the MAIN AC.
Thank you and best regards,
Felipe Navarro
The music continus singing for 3 ~ 5 seconds. The main power supply contains 330uf. But I use a Bleeder with 100k.
I have shorted the Input to the principal GND of the circuit and the HMMM continues.
The HMMM kill when I power off the MAIN AC.
Thank you and best regards,
Felipe Navarro
I found, when building an SRPP circuit, that it was more sensitive to hum from the heater in the bottom tube. But I found that I could use that "hummy" tube for the upper tube and not get anywhere as much hum. But the bottom tube needs to be low noise. See my web page
A screen or two above this spot in my web page
from that page: DAC tube preamp into a "SRPP" circuit. Uses a pair of 6111 submini tubes. These tube shave a mu of 20, gm of 5000 and plate resistance of 4K. This circuit offers lower output impedance and lower distortion. Measurements show the 2nd harmonic around 58 dB down and nothing else above a lower noise floor than those above. Output level is lower than with the 6112, but is cleaner. If you need to, use a lower noise from the heater tube for the bottom tube . As these are twin triodes, one tube is used for the bottom left and right channels, and the other twin triode used for top left and right channels. Using sockets like I did here allows tube rolling. A noisier tube can be used for the top tube.
Another possibility would be to run the bottom tube heater off DC. The upper tube could probably stay on AC. Another possibility is to use mil spec or industrial equivalents that were designed to be low noise from the heater. LIke a 7025 for a 12AX7.
A screen or two above this spot in my web page
from that page: DAC tube preamp into a "SRPP" circuit. Uses a pair of 6111 submini tubes. These tube shave a mu of 20, gm of 5000 and plate resistance of 4K. This circuit offers lower output impedance and lower distortion. Measurements show the 2nd harmonic around 58 dB down and nothing else above a lower noise floor than those above. Output level is lower than with the 6112, but is cleaner. If you need to, use a lower noise from the heater tube for the bottom tube . As these are twin triodes, one tube is used for the bottom left and right channels, and the other twin triode used for top left and right channels. Using sockets like I did here allows tube rolling. A noisier tube can be used for the top tube.
Another possibility would be to run the bottom tube heater off DC. The upper tube could probably stay on AC. Another possibility is to use mil spec or industrial equivalents that were designed to be low noise from the heater. LIke a 7025 for a 12AX7.
in last image (just now I realize that's almost same as "Anzai " line stage from Elector .....) you need 10UF across R6 (47K-lower resistor in divider)
like EC sez-twist wires for heater
route all DC paths away of AC lines ad ,if you must cross DC and AC lines,do that in 90^o angle........
have you enough capacity in main DC supply?
like EC sez-twist wires for heater
route all DC paths away of AC lines ad ,if you must cross DC and AC lines,do that in 90^o angle........
have you enough capacity in main DC supply?
choky said:
Yes! I have some 330uf on the DC Supply. I think this is enoght.
EC8010, I didn't wired the heater with a twisted pair. What is the difference in using a Twisted pair or not using a Twisted pair?
wa2ise, When I put a RCA 12BH7A on the place of 12au7, the HMMM get low But no much.
I have putted a BUFFER on the output and with mine Sennheiser HD580 I can see many HMMM on the deep.
Thanks for the replys and best regards,
Felipe Navarro
Tightly twisting the wire makes the stray magnetic fields cancel. If your heater wiring isn't twisted, then it could well be the cause of your hum. The only way you can say for certain what's causing hum is to cure it, then you know what the cause was. Without having it right in front of me to peer at it from all directions, probe it with an oscilloscope, and listen, it's hard to make predictions.
In Rose - The decoupling cap with 0.47uf 400v rating
In Yellow - The C1 and R3
In Blue - The R2 and C2
In Green - R7 - I put the 1meg resistor in only one channel to see the difference in the Headphone
In Red - The IDE cable who I used to conect the INPUT to the Potentiometer.
In this photo you can see better the WIRE who I have putted underground the board. This wire is B+
In Yellow - The C1 and R3
In Blue - The R2 and C2
In Green - R7 - I put the 1meg resistor in only one channel to see the difference in the Headphone
In Red - The IDE cable who I used to conect the INPUT to the Potentiometer.
In this photo you can see better the WIRE who I have putted underground the board. This wire is B+
Attachments
choky said:you still need 10UF cap across R6
but-first-try to move these xformers at least 20 cm further
hehe now Serbian lessons in Engrish:
proper sentence is :
"I love to make amplifiers, its my life!"
Choky,
In here I have a 47uf 200v capacitor across the R6. You can see this capacitor. The black capacitor with a FJ.
I willl move this Xformers, but now I haven't solder :x Tomorrow I will buy more solder and make this.
Yes! I love to make amplifiers.
Best Regards and Thanks,
Felipe Navarro
Re: heater wiring
Is the DC voltage in the heater the best option, isn't it?
I think the best option is a DC Heater. Am I correct?
Best Regards,
Felipe
SY said:EC, I think you were right, but for the wrong reason. He's using DC on the heaters. But... as someone always hectors me about (who could that be?), common mode hum pickup could be an issue.
Is the DC voltage in the heater the best option, isn't it?
I think the best option is a DC Heater. Am I correct?
Best Regards,
Felipe
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