LOL is it any wonder that im confused?
thanks all the same
Is it there?
read D.Joffe for explanation and solution for multichannel sources into multichannel receivers (Power Amplifiers) that have a ground loop between the interconnects.LOL is it any wonder that im confused?
thanks all the same
Just recently someone posted a sch showing this for a pre-amp input, where it's use is just as valid.
This was the first time I had seen the solution applied to a pre.
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is what where?Is it there?
are you going to answer post38?
is what where?
are you going to answer post38?
Look at an ST-70 input circuit for the ground path.
read D.Joffe for explanation and solution for multichannel sources into multichannel receivers (Power Amplifiers) that have a ground loop between the interconnects.
Just recently someone posted a sch showing this for a pre-amp input, where it's use is just as valid.
This was the first time I had seen the solution applied to a pre.
thanks
looking at the way he split the plate load resistors, could he be thinking balanced outputs?
my take is to replace that pot with a 470k resistor, then move that pot to input instead...
the last thing you'd want in any tube amp is to change operating points,
you change the signal input level, but you want the gains of stages fixed....
in my tube amp, all ground wires return to the psu last cap negative lead and
that point is the point that connects to chasis metal frame...single point star...
this worked for me all the time, my amps are quiet, no hum and no hiss...
at this point, carefull attention to flament wiring is also a must,
twisting the flament leads, grounding filament winding center tap or a vrtual center tap,
or lifting it with dc voltage bias, all these taken together helps...
and this last one takes care of the buzz...
once you learn these, then all your succeeding bulds will be a breeze....
I actually never build this sch myself, so never mind about the correctness of that sch. But the problem with RCA interconnect cable is real. It does not matter how perfect your ground loop is, there remain 5% of problem remains as shared here #25 Humming sound in stereo amplifier | Page 2 | All About Circuits
Where I am talking about is exactly this remaining 5%. If 1 ohm ground lift resistor is omitted, you can hear 100/120 hz and spike along with 50/60 hums, that makes it more objectionable, ever the level is only slightly higher. First your amp must be quite sensitive to be able to hear. My OTL amp overall gain is over 100, it is dead quiet as gain is slightly reduced. So I guess ST70 sensitivity is also very good so hum buzz can be heard, I got < 30mV 50 hz hum in output now with 1 ohm resistor lift, , but no additional 100 hz and spike and buzz, the reason is due the high gain of front-end. If all these hums are below your amp sensitivities it's probably does not matter but can not say there isn't any problem? So appreciate review your options please see if you can identify it yourself?
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I actually never build this sch myself, so never mind about the correctness of that sch. But the problem with RCA interconnect cable is real. It does not matter how perfect your ground loop is, there remain 5% of problem remains as shared here #25 Humming sound in stereo amplifier | Page 2 | All About Circuits
Where I am talking about is exactly this remaining 5%. If 1 ohm ground lift resistor is omitted, you can hear 100/120 hz and spice along with 50/60 hums, that makes it more objectionable, ever the level is only slightly higher. First your amp must be quite sensitive to be able to hear. My OTL amp overall gain is over 100, it is dead quiet as gain is slightly reduced. So I guess ST70 sensitivity is also very good so hum buzz can be heard, I got < 30mV 50 hz hum in output now with 1 ohm resistor lift, , but no additional 100 hz and spike and buzz, the reason is due the high gain of front-end. If all these hums are below your amp sensitivities it's probably does not matter but can not say there isn't any problem? So appreciate review your options please see if you can identify it yourself?
if i were in front of your actual setup, i would be able to fix that in half of half an hour....
i am confronted with issues in my builds, but i usually get over them in no time.....
i have said all i can, the rest is up to you....
if i were in front of your actual setup, i would be able to fix that in half of half an hour....
i am confronted with issues in my builds, but i usually get over them in no time.....
i have said all i can, the rest is up to you....
HBRL and HBRR as the link to Dannel's article is interested I wish I could also sim the problem myself, I believe there is a difference in HBRL and HBRR and mine I already suspected ground lift the screen on both cable is not quite enough.. thanks for all the infoes.
Koo, you are not alone in not recognising the need for HBRR/HBRL.
You are also not alone in putting the added resistor in the wrong location.
Bonzai has it wrong in his amplifier wiring guide. He also has it wrong in the NX pdf build guide.
Yet whoever designed the layout of the NX PCB actually put the HBRR in the correct location even though this is different from the published schematics.
You are also not alone in putting the added resistor in the wrong location.
Bonzai has it wrong in his amplifier wiring guide. He also has it wrong in the NX pdf build guide.
Yet whoever designed the layout of the NX PCB actually put the HBRR in the correct location even though this is different from the published schematics.
I have added added resistor in wrong place? Ya in the begin I repeat others mistake, but my later mod will catch up because I have real thing in-front of me, I believed mine have fixed both HBRR/HBRL and RCA ground loop in one go (1 ohm), and the OTL amp hum fixed, take me many months to find a reasonable solution for RCA interconnect. It's not HBRR/HBRL problem to begin with it was when I put in both RCA cable. Again your're able to differential them, good, but pay attention to the actual issue applied and don't comment beyond the core issue of RCA interconnect say from DAC player (Although HBRR/HBRL is off the issue, I still thank for the comment and help!), or do you mean they're the same problem?Koo, you are not alone in not recognising the need for HBRR/HBRL.
You are also not alone in putting the added resistor in the wrong location.
Bonzai has it wrong in his amplifier wiring guide. He also has it wrong in the NX pdf build guide.
Yet whoever designed the layout of the NX PCB actually put the HBRR in the correct location even though this is different from the published schematics.
I don't understand what you are trying to explain.
Did you understand D.Joffe?
Did you see the need for HBRR/HBRL when using a multi-channel power amplifier?
Did you locate HBRR/HBRL in the recommended location?
Did that attenuate the interference enough to make a measurable difference?
Did you understand D.Joffe?
Did you see the need for HBRR/HBRL when using a multi-channel power amplifier?
Did you locate HBRR/HBRL in the recommended location?
Did that attenuate the interference enough to make a measurable difference?
I don't understand what you are trying to explain.
Did you understand D.Joffe?
Did you see the need for I don't understand what you are trying to explain.when using a multi-channel power amplifier?
Did you locate HBRR/HBRL in the recommended location?
Did that attenuate the interference enough to make a measurable difference?
I think you do, you just raised more questions than answer: I asked again if you can't answer don't bother though.
question or statement?I have added added resistor in wrong place?
no question here so show what you are referring toYa in the begin I repeat others mistake, but my later mod will catch up because I have real thing in-front of me, I believed mine have fixed both HBRR/HBRL and RCA ground loop in one go (1 ohm),
no question. I don't understand.and the OTL amp hum fixed, take me many months to find a reasonable solution for RCA interconnect. It's not HBRR/HBRL problem to begin with it was when I put in both RCA cable.
again no question and I don't understand.Again your're able to differential them,
who do you want to pay attention?good, but pay attention to the actual issue applied
you don't want comment about HUM and BUZZ. They are the topic !and don't comment beyond the core issue of RCA interconnect
I did not comment on a DAC schematic, did you post information to allow comment to be posted?say from DAC player (Although HBRR/HBRL is off the issue,
is this a request for comment/help?I still thank for the comment and help!),
That is a question- What is the same problem?or do you mean they're the same problem?
As I stated I don't understand what you are writing.I don't understand what you are trying to explain.
............
AndrewT; As I stated I don't understand what you are writing.[/QUOTE said:Here is the kick for you: my right channel hasn't got any tube plugged in so how is the left and right channel hum balance ever taken place? Now when I plug in both RCA cable the hum and buzz is much increased, so how come? Then I am able to fix the hum. Do you understand now??
Sounds like you have not read D.Joffe.
did you read my post 51 questions?
did you read my post 51 questions?
Did you understand D.Joffe?
Did you see the need for HBRR/HBRL when using a multi-channel power amplifier?
Did you locate HBRR/HBRL in the recommended location?
Did that attenuate the interference enough to make a measurable difference?
Sounds like you have not read D.Joffe.
did you read my post 51 questions?
yes, but i do read it, nothing about D.Joffe, but do you think there is a lot more info I need to fix the problem? You could provide a link or summary what it's all about, please "don't raise more info than fix"
read D.Joffe for explanation and solution for multichannel sources into multichannel receivers (Power Amplifiers) that have a ground loop between the interconnects.
Just recently someone posted a sch showing this for a pre-amp input, where it's use is just as valid.
This was the first time I had seen the solution applied to a pre.
File Type: pdf GroundingProblemsRev1p4DanielJoffe.pdf (209.9 KB, 14 views)
thanks
I don't understand what you are trying to explain.
Did you understand D.Joffe?
Did you see the need for HBRR/HBRL when using a multi-channel power amplifier?
Did you locate HBRR/HBRL in the recommended location?
Did that attenuate the interference enough to make a measurable difference?
Sounds like you have not read D.Joffe.
did you read my post 51 questions?
yes, but i do read it, nothing about D.Joffe, but do you think there is a lot more info I need to fix the problem? You could provide a link or summary what it's all about, please "don't raise more info than fix"
Chopchip managed to read it and thanked me.
You are doing nothing to help yourself !
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Chopchip managed to read it and thanked me.
You are doing nothing to help yourself !
How do know mine is not fixed? You can credit to yourself for a simple thank, if that is enough for you then why discredit me??
Edit: I thought he mentioned 1 (1.5) ohm resistor did you mention it?
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It is not that simple. The single resistor solution is just not good. Take the example from post 14. It does very little to prevent ground loop currents, plus the input and output interconnects are parallel to the resistor. The audio signal will return via the interconnects (and PE) instead of the resistor.
You should not just insert resistors and believe all is good just because the hum is reduced. You need to know at what cost.
You should not just insert resistors and believe all is good just because the hum is reduced. You need to know at what cost.
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