Sorry... 2x 180k... equals in series ca. 360K...
No, they are 180k.. brown, grey, yellow, gold
After or without grounding the pot is not matter... I think the touch noise comes from the tubes...
I have no oscilloscope...
Yes R16 and R17 are each ca. 360k...
Tommorrow I will take C10 and C11 out and test.. Thankyou!
The hum is a higher hum exact in the beginning when I push power....after 5 seconds a deeper hum joins in...
No, they are 180k.. brown, grey, yellow, gold
After or without grounding the pot is not matter... I think the touch noise comes from the tubes...
I have no oscilloscope...
Yes R16 and R17 are each ca. 360k...
Tommorrow I will take C10 and C11 out and test.. Thankyou!
The hum is a higher hum exact in the beginning when I push power....after 5 seconds a deeper hum joins in...
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signal cable grounds
Hi there h: IN pictures #2 and #4, you have input signal cables connected. Although you have grounded the input signal connections during earlier testing, try removing the input cables. Occasionally, I have developed high SPL hum from ground loops when other equipment was connected. Possibility occurring from the grounding method used by the other equipment manufacturer. Also, looking at P. Millet's pictures on his web site, I did not see the large white loop cables as shown in your construction, purpose? One end seems to be tapped off? ...regards, Michael
Hi there h: IN pictures #2 and #4, you have input signal cables connected. Although you have grounded the input signal connections during earlier testing, try removing the input cables. Occasionally, I have developed high SPL hum from ground loops when other equipment was connected. Possibility occurring from the grounding method used by the other equipment manufacturer. Also, looking at P. Millet's pictures on his web site, I did not see the large white loop cables as shown in your construction, purpose? One end seems to be tapped off? ...regards, Michael
The white looped cables are not connected... just not in use, but I don't want to shorten them. One is the CT from the power trans and the other two put together the UL screen wires from the OPTs... probably for use in a PP configuration...
I tried the input signal in two different configurations here...
1. with an iPod and noname testing speakers...
2. with my cd player and the good speakers...
Both showed same symptoms...
Yestreday I thought it is a wrong electronic device, resister or so...
But now I only can rely on the professional helpers here at diyaudio... 🙂 Thanks!
Still hums audible after removal of C10 and C11... but not so strong... 🙂
Should I have bridged the holes? No music...
Should I put them back in? 🙂
I tried the input signal in two different configurations here...
1. with an iPod and noname testing speakers...
2. with my cd player and the good speakers...
Both showed same symptoms...
Yestreday I thought it is a wrong electronic device, resister or so...
But now I only can rely on the professional helpers here at diyaudio... 🙂 Thanks!
Still hums audible after removal of C10 and C11... but not so strong... 🙂
Should I have bridged the holes? No music...
Should I put them back in? 🙂
I know you said that you have grounded the ALPS pot, but from the pictures it does not look like you have actually done that - I usually solder a short ground cable to the top screw on the back side of the pot.
...just a thought, if you haven't tried it already.
...just a thought, if you haven't tried it already.
Thanks for the advice! Done that with an aligator wire clip... 🙂
wfmali is maybe on a successfull path... 🙂
wfmali is maybe on a successfull path... 🙂
[wfmali is maybe on a successfull path... 🙂]
Hmm, no real path, we can just try to give some hints remotely...
But dont bridge C10/C11, this will not work!! Leave them out for the time beeing, your amplifier has to be hum-free this way first, than you can put them back in. Since ist still hums, you have to verify that your supply voltage is ok. A diode might be bad (if the hum is loud...)
You wrote that you have immediate hum when you switch it on (tubes still cold), this sounds like magnetic coupling. You may want to substitude the two chokes by 100R/5W resistors, guess this was mentioned before, and see if this changes anything...
Hmm, no real path, we can just try to give some hints remotely...
But dont bridge C10/C11, this will not work!! Leave them out for the time beeing, your amplifier has to be hum-free this way first, than you can put them back in. Since ist still hums, you have to verify that your supply voltage is ok. A diode might be bad (if the hum is loud...)
You wrote that you have immediate hum when you switch it on (tubes still cold), this sounds like magnetic coupling. You may want to substitude the two chokes by 100R/5W resistors, guess this was mentioned before, and see if this changes anything...
I think he said he has 'higher' hum at switch on, 'lower' after warm-up. Sounds to me like a buzz (higher freq) from rectifiers, which points to a ground loop issue. 'Lower' freq probably mains hum coming in with the amp coming on which is a different issue.
The flying long leads with CT voltage are also a risk.
BTW Have you asked Pete? I find it curious that everybody and his grandmother is asked here except the guy who designed it in the first place...
Jan
The flying long leads with CT voltage are also a risk.
BTW Have you asked Pete? I find it curious that everybody and his grandmother is asked here except the guy who designed it in the first place...
Jan
Yesterday I ordered 4 new diodes... should be here tommorrow...
Before having to cut the choke lines for resiter sub, I will wait for the new diodes...Cree C3D02060A SiC-Diode 4A 600V Silicon Carbide Schottky Diode TO220AC 855418 | eBay
Before having to cut the choke lines for resiter sub, I will wait for the new diodes...Cree C3D02060A SiC-Diode 4A 600V Silicon Carbide Schottky Diode TO220AC 855418 | eBay
Will shorten the looping cables... Pete's last reply: You posted photos on DIYaudio of this build, right? It looks like you used a wooden chassis? I had noise issues in a metal chassis until I provided a good ground connection to the chassis. So I think your issues may be related to using a wooden chassis - or at least, that is probably why I did not have any noise issues. You can try to do some shielding with metal or foil. I use self adhesive copper tape on wood sometimes - you can solder to it and it works well, but is not cheap. One thing you almost certainly need to do is provide some ground connection to the volume control bushing and case. Maybe a wire connected between the bushing, held by the nut, will work. There may also be some coupling from the power transformer to the input traces, which run from the back to front. That would be one area you might need to shield. Also, with 240V mains, there is more risk of coupling from the mains into the low level circuits. You may also want to experiment with the ground loop breaker, D1. You may get better noise with a direct connection between power supply ground and mains ground. Pete Another thing I have noticed is that earth to board ground is 16MOhm... speaker - to chassis plate or earth from main socket... Just jumped the two chokes with 120Ohm resistors... MORE HUM!!! Now I wait for the diodes... Thankyou! 
Did you check the tubes?
Tap the tubes gently with a wooden chopstick. If they sing, replace them.
Tap the tubes gently with a wooden chopstick. If they sing, replace them.
Sure they sing... 🙂
I mentioned that in the beginning, but no comment...
both pairs I have are very microphonic to being hit with a chopstick...
Ordered them from USA because they are rare here in germany...
I mentioned that in the beginning, but no comment...
both pairs I have are very microphonic to being hit with a chopstick...
Ordered them from USA because they are rare here in germany...
It is unlikely, but you might want to move those OPT tap wires so that they are not near the input or tubes. There could be enough stray feedback to cause an oscillation. Hard to tell without an oscilloscope.
It seems to me that any hum present before the tubes have heated enough to conduct must be from magnetic coupling between the power transformer or chokes and OPT. I wonder if Edcor correctly wound the power transformer for 50Hz? If not it's stray field may be large. I guess you could try moving the power transformer far away (like 0.5 meter) and extending the wires...
Pete
Hi Pete! Thanks for listening 🙂
In my first set up on a piece of wood, the transes were all lying with original wire length... so, the power trans was about 20cm behind the board... I also did bend the connecting wires with no audible satisfaction...
I tried moving the power trans and OPTs around up and down but with no changeing of hum strength or weekness...
Please let me say: the board looks great and is not the primary problem! 🙂
Today I will replace the diodes and put the power trans 50cm away... 🙂
BTW: Is somebody else for new old tubes?
In my first set up on a piece of wood, the transes were all lying with original wire length... so, the power trans was about 20cm behind the board... I also did bend the connecting wires with no audible satisfaction...
I tried moving the power trans and OPTs around up and down but with no changeing of hum strength or weekness...
Please let me say: the board looks great and is not the primary problem! 🙂
Today I will replace the diodes and put the power trans 50cm away... 🙂
BTW: Is somebody else for new old tubes?
Does it also hum without tubes? Trying this, you may want to watch the hv supply voltage without load on the transformer not to exceed the voltage rating of your capacitors.
GOOD MORNING! Hums without tubes...did that a few days ago... at present the amp is taken apart for future soldering... 🙂
That's a clear give-away, isn't it?
BTW Why new diodes??
Jan
... and another clear pointer!
Thought: if there are no tubes (if it isn't really doing any 'amplification') how does the hum get into the output transformer?
Jan
I've just completed Pete's DCPP with the Edcors suggested. One thing I've noticed is the hum which I can only put down to mechanical noise from the PT. [Not present when scoping the speakers etc]
Searching the forum here I found a few posts along these lines (using Edcors), all from people outside of the US / Canada. The conclusion was the PT is designed for 60Hz/120Vac conditions, and operating at 50Hz/230Vac, whilst in the design envelope, resulted in the hum...
Searching the forum here I found a few posts along these lines (using Edcors), all from people outside of the US / Canada. The conclusion was the PT is designed for 60Hz/120Vac conditions, and operating at 50Hz/230Vac, whilst in the design envelope, resulted in the hum...
Sorry for confusion!
Dead quiet without tubes and inserted C10, C11!!!!!!
Power trans 50cm behind the board...
Dead quiet without tubes and inserted C10 C11, power trans only in one direction direct behind the board
Alot of hum tubes inserted either ways...
That really sucks! Thankyou!
Conclusion: Get a new PT made in germany... 🙂
It may not be the same case in your situation, just an idea. The hum doesn't really bother me, but it is there and seems to be worse as the PT heats up. Which it does to a high level!
Toroidy.pl do a PT which is very close to the Edcor spec which I may look at in the future.