Hi ZM,
I rotated the toroid and cap bank. Does this wiring look correct
for the grounding?
I'm kinda confused as there has been few different ways to wire it.
Thanks
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Thank you sir. All rewired and hum is still there.
The hum is only heard when placing ear next to speaker.
About one foot away, I cannot hear it even in a quiet room,
ambient noise is louder.
My final question is if I swap out the Antek 12V 400VA toroid with
a Piltron one, what are the chances of the hum reduced or go away?
Cool. I am happy with you,-)
May be, you could reduce the hum a little bit more.
Whether ground-star or rgound-plate should be necessary: do not regard my/the graphed star.
RCA only one channel to ground.
Speakers at the star.
Final I - my opinion - both windings for (+) and (-)
Some ideas.-)
May be, you could reduce the hum a little bit more.
Whether ground-star or rgound-plate should be necessary: do not regard my/the graphed star.
RCA only one channel to ground.
Speakers at the star.
Final I - my opinion - both windings for (+) and (-)
Some ideas.-)
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Assuming the main difference between the two transformers mentioned would be their stray magnetic field, swapping them would make very little difference I think. You've moved the transformer away from the circuit and there was no notable change in hum levels, right? That would indicate that the circuit is not picking up a stray field from the transformer, I'd say.
You've moved the transformer to the other side of the capacitor bank. That should have taken it outside a potential ground loop. No change in hum, so again indicating that the circuit is not picking up a stray field.
Lastly, I'm still somewhat worried with PSU filtering. My mini aleph (speaker and headphone) runs off 3*33000uF per rail (CCRC with 1R resistor) and it's quiet enough for headphone listening. I could measure the residual ripple voltage this weekend.
You've moved the transformer to the other side of the capacitor bank. That should have taken it outside a potential ground loop. No change in hum, so again indicating that the circuit is not picking up a stray field.
Lastly, I'm still somewhat worried with PSU filtering. My mini aleph (speaker and headphone) runs off 3*33000uF per rail (CCRC with 1R resistor) and it's quiet enough for headphone listening. I could measure the residual ripple voltage this weekend.
Thanks cumbb. The speaker - output tied to star ground is what I had
originally.
The input signal ground wiring scheme looks like what I use in tube pre amp.
Yes, this is a fickle pickle. One of the last things I did before moving
toroid and cap position, I added another 33,000uF on the first stage.
I did not have the correct power resistors so essentially it was
CCRC, 66,000uf to R to 33,000uf. The ripple at speaker output went from 2mV to 1mV, alas, HUM is still there.
Only other stupid question I have to bring up is instead of 221ohm fixed resistor
on the input, Im using a 500ohm multiturn trimmer, this should not cause hum?
That is only thing not part of the original schematic. this is to adjust dc offset.
no toroid swapping then. end of the line, lol
can you post pictures now
that amount of hum is almost irrelevant now
is it changing with inputs grounded , inputs open , inputs connected to source ?
the hum was same before I did any modifications. hum was never an issue for me, my friend with his 94dB speakers says he can hear the hum 4-5 feet away so it is why I was trying to reduce or remove hum altogether. My speakers are 91dB sens.
some builders said they get no hum or slight hum like my unit. this
hum seems quite normal for this build is my only conclusion.
here is photo.
Thank you.
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hum remains same with or without source connected
there was never any difference in hum when inputs grounded or using
my 100ohm rca shorting plugs.
could just have been going in circles with this. still would
love to know how to kill hum but I don't have those skills.
learned a thing or too though, like even with super heavy duty filtration,
ripple very low but still can hum. I always thought reducing ripple reduces hum
but I am certainly not hearing that with my unit.
there was never any difference in hum when inputs grounded or using
my 100ohm rca shorting plugs.
could just have been going in circles with this. still would
love to know how to kill hum but I don't have those skills.
learned a thing or too though, like even with super heavy duty filtration,
ripple very low but still can hum. I always thought reducing ripple reduces hum
but I am certainly not hearing that with my unit.
Most "hum" problems are due to wiring incorrectly.
That "star ground" in the middle of the smoothing capacitor charging plate could be the culprit.
You must completely separate the capacitor charging circuit from any/all audio voltage references !
Can you measure the output noise+hum using a dmm set to 199.9mVac?
Post the measurement here.
That "star ground" in the middle of the smoothing capacitor charging plate could be the culprit.
You must completely separate the capacitor charging circuit from any/all audio voltage references !
Can you measure the output noise+hum using a dmm set to 199.9mVac?
Post the measurement here.
could you provide a wiring diagram of what you mean sepearate charging circuit from audio ref. voltages. I may have already wired the way you said it previously.
yes, DMM measures 2mV at speaker outputs. I added 2 more caps in front end,
CCRC, it dropped to 1mV on speaker output but hum still there.
conclusion was cap bank is doing its job with ripple but hum is still present.
A good output noise+hum is <0.1mVac, i.e. 0.0mVac on the 199.9mVac scale of a DMM.
Barely acceptable for normal sensitivity speakers is ~0.3mVac
You are many dB worse than this.
Have you read this yet?
Audio Component Grounding and Interconnection - diyAudio
Barely acceptable for normal sensitivity speakers is ~0.3mVac
You are many dB worse than this.
Have you read this yet?
Audio Component Grounding and Interconnection - diyAudio
it's already at 66,000uf per rail, not much else can be done to improve
the cap bank. I add 2 more caps, 99,000uf per rail, it dropped to 1mV.
I think these values are above and beyond most builds. this a mini aleph
version, not high power one.
yes, I read that article, the elliot sound lab article and few others.
I get some of it but not all. a lot of theory not practical real application
wiring. maybe there is but I cannot translate it into real world wiring.
I followed other's suggestions here, swapping toroid and cap bank
as the master does it plus various grounding schemes. The hum
remains a constant, did not change in volume level. just always there regardless
of what I tried.
Other feedback, not here but I was told anything under 5mV ripple is good.
Your .1-.3mV spec, how many aleph builders here actually acheive that, really curious...
All I am trying to get across is with 99,000uf per rail and I get 1mV ripple,
like I said, don't have a clue how it can be improved any further to acheive
.1-.3mV ripple. the hum did not decrease in volume from 2mV to 1mV,
there should have been some reduction here, if ripple and hum are same?
I also tried a power strip made for audio, with built in common mode filter.
hum is still there using the power strip.
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the 0.0mVac to 0.3mVac is Hum+Noise at the output of the power Amplifier.
It is not the ripple on the PSU supply rails.
Going back to posts93 & 95
I said
You must not take any audio grounds or audio references from the middle of the charging plate.
That is one of the dirtiest places inside your amplifier.
It is not the ripple on the PSU supply rails.
Going back to posts93 & 95
I said
You must not take any audio grounds or audio references from the middle of the charging plate.
That is one of the dirtiest places inside your amplifier.
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