You need to give a bit more information and some pictures. Is the noise happening at all level of the volume, does it happen when the phono preamp is connected or even when phone preamp is not connected?
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When i use my phono this have pup pup noise ! I have noise without i use phono ! But when i use my iPhone i dont have noise!
Sorry for my english
I have noise only on phono !
When i use my phono this have pup pup noise ! I have noise without i use phono ! But when i use my iPhone i dont have noise!
Sorry for my english
I have noise only on phono !
I am not sure i understand it.
When the phone preamp is connected to the line amp section you have no pup pup noise. When you disconnect the phone preamp section you have the pup pup noise. Is this correct?
When the phone preamp is connected to the line amp section you have no pup pup noise. When you disconnect the phone preamp section you have the pup pup noise. Is this correct?
It seems to be motorboating oscillations in a preamp that has a well designed B+ supply and no feedback, which shouldn’t happen. Can you look at the HV supply while the put-put noise is occurring and see if there is a corresponding disturbance on the B+ supply. The other issue could be around the cascode biasing used in the stock circuit. The circuit may be fussy about the tube quality and could possibly oscillate if a tube is not up to scratch. So, I would change out the tube in the cascode stage of the phono anmp and see if it makes any difference. Also make sure you have the correct resistor and capacitor values in the B+ power supply filter and that the DC voltages for each stage are near where they should be. The power supply filtering on the board is a bit convoluted and perhaps you have a wrong resistor value that could be putting a time constant in the power supply that allows it to oscillate. That’s all I can come up with at this point with the info given. Also, if you have changed capacitor values anywhere in the circuit let us know what changes were made.
when i listen to phono i have noise only ! When the phone preamp on i have pup pup noise from left saide.
LT1963A which side of the supply you use it? the 12.6V or the 300V? The post above from Bfpca is talking about 300V high voltage rail.
I have noise when I start the m77! after 5/6 minutes the noise disappears! I clean PCB aigen ! but when I use the M77 with my DAC I don't have noise!
I have 275V on B+
But 185V on CAP !
See photo !
Thanks 🙏🏼
I have 275V on B+
But 185V on CAP !
See photo !
Thanks 🙏🏼
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My kit arrived. I am pretty impressed. I got the entire kit, PCB with components, transformer and the case. The transformer looks good, the case has all the holes predrilled. Of course the RIAA components and the coupling capacitors needs to be better ones. The price of $360 was not bad at all and it was shipped FEDEX. I am not sure if I am allowed to share aliexpress vendor info on this forum. If you would like the info please let me know.
Now my question comes. I am testing the power supply. I modified as advised the 12.6V voltage, I am getting around 14.7V with no load. I forgot to turn the trim pot to max, I might have to replace the Zenner because is reads across of it almost 16V.
The high voltage I get nothing. I got from eBay a 6x4WA rectifier tube, the filament for the tube doesn't turn on. I thought 6x4WA is a direct replacement to 6x4, am I wrong?
I have a Chinese 6Z4 for this one the filament turn on but I have no high voltage as far as I know, i just read about 6Z4 and the the anode, cathode are different pins. I don't have the 12AY7 tubes yet, I am doing all the voltage testing without the tubes. I found the voltage check point for 12.6V, where should I check High Voltage if the 12AY7 are not installed? AC voltage reads correct.
Now my question comes. I am testing the power supply. I modified as advised the 12.6V voltage, I am getting around 14.7V with no load. I forgot to turn the trim pot to max, I might have to replace the Zenner because is reads across of it almost 16V.
The high voltage I get nothing. I got from eBay a 6x4WA rectifier tube, the filament for the tube doesn't turn on. I thought 6x4WA is a direct replacement to 6x4, am I wrong?
I have a Chinese 6Z4 for this one the filament turn on but I have no high voltage as far as I know, i just read about 6Z4 and the the anode, cathode are different pins. I don't have the 12AY7 tubes yet, I am doing all the voltage testing without the tubes. I found the voltage check point for 12.6V, where should I check High Voltage if the 12AY7 are not installed? AC voltage reads correct.
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Filament power question resolved. Today I received the JJ tubes and I was able to test it under load.
Under load just the line preamp section(4 tubes), voltage is 12.56V steady, when the phono preamp is turned on(all 8 tubes) then filament voltage is 11.7V.
Under load just the line preamp section(4 tubes), voltage is 12.56V steady, when the phono preamp is turned on(all 8 tubes) then filament voltage is 11.7V.
I have questions about 12.6v dc filament with one recommend you modify i that witch MJ3001 + zener or use i LT1963A low noise ? with of they have less noise ?
Thanks for your help
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