| Magura |
Pics not working :bawling:
Magura :) |
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| AndreaFx |
| quote: | Originally posted by Magura
Pics not working :bawling:
Magura :) |
(WARNING! To view, copy and paste the link in a new Explorer's page)
You do it? ;) |
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| AndrewT |
Hi,
what is that band around the top of the toroid?
Is it a shorted turn? |
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| AndreaFx |
| quote: | Originally posted by AndrewT
Hi,
what is that band around the top of the toroid?
Is it a shorted turn? |
Sorry but i don't understand the terms "shorted turn" :(
I use the bracket (aluminium) around the trafo to stabilize them in vertical position. There's not enought space to place orizontally.
Under the bracket and trafo i put a neoprene sheet do reduce the mechanical hummm.
I know that is not the best position because the bracket warm a lot during normal use of the amply
There are other problems with the bracket? |
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| AndrewT |
Hi,
the clue is that the bracket got warm.
Remove it before you switch on again.
The bolt and the aluminium act like a single turn around the toroid and pulls enormous current making the bracket warm, but much worse it causes severe overheating of the primary and risks damaging the toroid beyond repair.
There must be numerous warnings about shorted turns in the Pass Labs section!!! |
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| Alain Dupont |
AndreaFx,
The aluminium braket could lead to a shortcut!
If the bolt and braket on the top of the toroid are connected without insolation washers...
Nice job! :)
Regards.
Alain. |
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| AndreaFx |
Thanks guys for the information ;)
The "shorted turn" can caused problem at the sound quality or only at the trasformer?
I use the rubber under the insolation washers on both sides of the trasformer.
I can use another rubber upon the washers?
would prefer not to cut the bracket........if possible! |
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| Alain Dupont |
AndreaFx,
I understand your concern for handling the toroid weight.
If this is not creating a shortcut ; otherwise it could load the toroid real badly...
A shortcut of one turn of heavy aluminium and bolt would lead to
dozens of amps and could destroy the toroid... :hot:
Neoprene washers are fine, but they must wistand heat ; use the same
Neoprene as the big insolation washer sold with the toroid.
Regards. |
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| AndreaFx |
| Ok Alain i try to do as you are suggesting, thank you ;) |
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| AndreaFx |
If I link the trafo in this way? It's Okay?
The shorted turn it's deleted?
I found another small (I hope) problem and i need help.
When i power on the ampli with the source detached, all it's ok, but when i attack the RCA cable (source is off) a noise (like Zzzzzzzz) coming out from the speaker.
which may be the problem? A ground loop? :( |
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| Alain Dupont |
AndreaFx,
Yes that's much better ; the shortcut while mounting the toroids verticaly is common,
but not often explained on manufacturers sites...
Probably ground loop,
Check if all your masses go to the same point, and if it's separated from the chassis.
Check if cables cross the power supply 60 Hz primary cable at right angle.
Are your Input RCA jacks insolated from the chassis...
Try rotating the toroid, and see if there is a position where the buzzz is lower
Take care, and good luck with your projects.
Alain. |
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| AndreaFx |
Thanks Alain ;)
-All the masses go to the same point, of course! But i read ever that the masses be united with case........it's an error? :confused:
-The primary cable is separated by all cables
-The input RCA are insolated from chassis
-I will try some test with toroid this week-end ;) |
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| AndreaFx |
I've eliminated the shorted turn with the cut of the bracket. Now the temperature it's ok!! ;)
For the noise, i do some tests.......the problem disappear only when disconnecting the earth from power cable :dead:
There're another method to resolve the problem now that I know the reason? |
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| AndrewT |
| quote: | Originally posted by AndreaFx
For the noise, i do some tests.......the problem disappear only when disconnecting the earth from power cable |
What if the power amp alone is connected to the speakers and the input has a shorting plug fitted? |
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| AndreaFx |
| quote: | Originally posted by AndrewT
What if the power amp alone is connected to the speakers and the input has a shorting plug fitted? |
What is a shorting plug? How can I build? |
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| AndrewT |
shorting input plug = RCA plug with a shorting wire link between the pole and the barrel.
Alternatively you can make up a set of input plugs. zero ohms, 50r, 100r, 200r, 1k0, 10k. A pair of each value labeled and put on the shelf for future testing. |
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| AndreaFx |
| quote: | Originally posted by AndrewT
shorting input plug = RCA plug with a shorting wire link between the pole and the barrel.
Alternatively you can make up a set of input plugs. zero ohms, 50r, 100r, 200r, 1k0, 10k. A pair of each value labeled and put on the shelf for future testing. |
Oooook all clear, tanks........i can try to connect positive and negative input with a wire for a test.
After i report here the result, ok? |
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| AndreaFx |
| This is the layout of my mass........it can help for the problem solution? ;) |
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| AndrewT |
Hi Andrea,
rewire your mains and transformer.
The mains Safety Earth (third wire) must go straight to chassis and be PERMANENTLY connected with a MECHANICAL fixing, not soldered.
The two secondary windings must go to the four connections on the PSU board. |
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| AndreaFx |
| quote: | Originally posted by AndrewT
Hi Andrea,
rewire your mains and transformer.
The mains Safety Earth (third wire) must go straight to chassis and be PERMANENTLY connected with a MECHANICAL fixing, not soldered.
The two secondary windings must go to the four connections on the PSU board. |
Sorry Andrew, you can modify my design in the right way? So is more clear for me!
Thanks |
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| AndreaFx |
I do another test, I tried to separate the power board from amply board (see the attachment).
the situation has worsened :dead: :bawling: |
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| Peppe |
Andrea,
if I were you, I will try what Andrew said: ;)
| quote: | Originally posted by AndrewT
The two secondary windings must go to the four connections on the PSU board. |
Cheers
Peppe |
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| Andypairo |
Ciao Andrea,
from my experience with Aleph30 (2 built) I can suggest:
-Use the gnd area on the power supply pcb as star ground
-Bring there all gnd connections, including signal gnd
-Connect safety earth from IEC socket to case but not directly to GND. This will prevent earth loop if another appliance is connected to earth without loosening safety.
In case you can connect them with a resistor, a RC network or whatever you like.
I also strongly suggest the use of a separate rectifier bridge for each secondary winding. With your PCB it must be wired externally but I think it is worth it.
Ciao!
Andrea |
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| AndreaFx |
News:
I've modify the layout (sorry but attach file don't working) and now the problem is resolved ;)
Thank you all for helping!!
Last thing........very strange :dodgy:
If I link both RCA, ONLY in speaker right feel a slight hum.....if I reverse the link, the hum exit from left speaker.
I suppose that the problem is not the Aleph......right? |
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| Peppe |
Good news Andrea,
if you reverse the cables and the hum chance channel, no.
Try with other source and/or others cables.
Enjoy tour Aleph
Cheers
Peppe |
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| AndreaFx |
| quote: | Originally posted by Peppe
Good news Andrea,
if you reverse the cables and the hum chance channel, no.
Try with other source and/or others cables.
Enjoy tour Aleph
Cheers
Peppe |
Yeah, i'll try........first with another cable, after with another source ;)
Now, Aleph needs a pre......P 1.7 or what? |
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| Peppe |
BOZ because of simplicity (IMHO good starts for newbie)
B1 because (with your speaker) the gain you need is enough
P1.7 because of balanced in/out
Any other you like...
It is up to you ;)
Peppe |
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| AndreaFx |
| quote: | Originally posted by Peppe
BOZ because of simplicity (IMHO good starts for newbie)
B1 because (with your speaker) the gain you need is enough
P1.7 because of balanced in/out
Any other you like...
It is up to you ;)
Peppe |
Mmmm i think P1.7 is the best choice because I want to connect through balanced out pre with final.
there are no tube pre made by pass?
know where i find the PCB for P1.7?........Mmmmm KK-PCB or where?
I Attach the mass layout that i used |
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| AndrewT |
Hi A,
now add a connection from Audio Ground to Safety Earth, to meet the requirement:
all exposed conductive parts must be connected to Safety Earth. |
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| Peppe |
Edit: Andrew was faster than me. :)
Andrea,
I see NO star-ground! :eek:
Follow what Andrea said: :smash:
| quote: | Originally posted by Andypairo
-Use the gnd area on the power supply pcb as star ground
-Bring there all gnd connections, including signal gnd
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Mmmm... 3 Andrea in this thread! :clown:
Ciao
Peppe |
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| AndreaFx |
| quote: | Originally posted by Peppe
Edit: Andrew was faster than me. :)
Andrea,
I see NO star-ground! :eek:
Follow what Andrea said: :smash:
Mmmm... 3 Andrea in this thread! :clown:
Ciao
Peppe |
.......But If i attach the Earth with the GND on the power pcb the hum restart :bawling:
Argh!......this amply make me crazy :dead: |
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| Andypairo |
You don't have to connect safety earth and signal gnd with a short, start with a low value resistor (10 Ohm or so) and report what happens.
Do you have other earthed appliances in the audio chain ?
Ciao
Andrea
Btw my suggestion included to wire the input socket gnd direct to the power supply pcb. |
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| AndreaFx |
| quote: | Originally posted by Andypairo
You don't have to connect safety earth and signal gnd with a short, start with a low value resistor (10 Ohm or so) and report what happens.
Do you have other earthed appliances in the audio chain ?
Ciao
Andrea
Btw my suggestion included to wire the input socket gnd direct to the power supply pcb. |
Ok i try with a resistor and report what happens. Watt of resistor is important?
Mi source CD have a earth.
Input gnd RCA directly to the Power PCB or through the Main Amplifier PCB is the same thing IMHO.......see the layout of Main PCB |
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| Andypairo |
Ciao,
since you already have the CD earthed you can connect the gnd of the amp with a resistor (at least 1W) or with a RC network.
Connecting the gnd of input sockets (I hope these are isolated from the chassis!) to the main board won't do any harm if almost no current flows into the connection between main board and star ground.
Hint: where do you connect the speaker return?
Ciao!
Andrea |
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| AndreaFx |
Yes the RCA and speaker plug are isolated from chassis ;)
I connect the speaker return on the Main Amplifier PCB (CGND) |
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| Andypairo |
With this wiring the return current form the speaker will flow into the wire between the 2 pcbs, modulating the voltage of the "gnd" of the main pcb.
Do you understand now why I said that is better to bring all gnd wires to the star ground?
Cheers
Andrea |
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| AndreaFx |
| quote: | Originally posted by Andypairo
With this wiring the return current form the speaker will flow into the wire between the 2 pcbs, modulating the voltage of the "gnd" of the main pcb.
Do you understand now why I said that is better to bring all gnd wires to the star ground?
Cheers
Andrea |
Ok Andy, i understand ;) ........I'll try tomorrow to modify the wiring when you advice. |
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| AndreaFx |
Sorry for the delay........home free, the girl......Eheheheheheh :clown: ;)
See the attached file, in this way the hum desappeared.
The mass loop now it's ok? I can close the case and listen a lot of good music, or i do another modify? |
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| Andypairo |
I still don't see the speaker return.
If connected as adviced it should be OK, but since you said it works fine...
Ciao!
Andrea |
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| AndreaFx |
| quote: | Originally posted by Andypairo
I still don't see the speaker return.
If connected as adviced it should be OK, but since you said it works fine...
Ciao!
Andrea |
I modify the layout with the speaker connection ;)
8,5 Ohm for the resistor it's ok or a I can increase/decrease the value? I use 8,5 because I had available, but i can try with 4, 6 or 10 Ohm if it's better.
thanks for support Andy........ I must offer you a beer ;) |
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| salas |
| Great looking amp. Bravisimo!;) And how do you like the sound? What kind of speakers do you drive? |
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| AndreaFx |
| quote: | Originally posted by salas
Great looking amp. Bravisimo!;) And how do you like the sound? What kind of speakers do you drive? |
Thanks salas ;)
I haven't tried the ampli so good because first I want resolve the loop ground.
To date it played about 3 hours with a pair of DIY's speakers with morel component: model York
http://www.audiokit.it/ITAENG/KitDi.../MOREL/York.gif
Very good in my small room :) |
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| AndrewT |
Hi Andrea,
the value of the Power Resistor in the Safety Earth to Audio Ground connection is not important.
What is MUCH more important is that it survives longer than the mains fuse if mains were to touch the Audio Ground side.
Most recommend that a pair of Power Diodes wired in inverse parallel be added in parallel to the Power Resistor.
See ESP for a diagram of this. |
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| AndreaFx |
| quote: | Originally posted by AndrewT
Hi Andrea,
the value of the Power Resistor in the Safety Earth to Audio Ground connection is not important.
What is MUCH more important is that it survives longer than the mains fuse if mains were to touch the Audio Ground side.
Most recommend that a pair of Power Diodes wired in inverse parallel be added in parallel to the Power Resistor.
See ESP for a diagram of this. |
The power resistor is very big
http://www.audiokit.it/ITAENG/Resistenze/100_4555-1.jpg
Should survives mutch that mains fuse for me.
But.......you have an exemple of the circuit with diodes? What is ESP? |
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| AndrewT |
Andrea,
I think you may misunderstand the duty that this resistor may have to face if a mains wiring fault or transformer fault develops that connects Live to Audio Ground.
It may have to dissipate P=V^2/8.5ohms ~5.7kW until the fuse blows and the arc extinguishes.
How long will that 10W resistor last trying to dissipate 5.7kW?
I don't know, do you?
How long will a mains fuse last passing ~25A? Look up the tables for your chosen fuse manufacturer and value. |
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| salas |
| You will use 2pieces 5 Ampere diodes, or much bigger, or a diode bridge. One cathode goes to other's anode. This pair you wire in parallel to your 8.5R. So if big current must pass in some failure, it will go through one diode no matter the polarity. |
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| salas |
| Here is one example. |
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| AndrewT |
Salas,
ESP has asked that you refer enquirers to his site and not post extracts even if attributed. Your post isn't. |
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| AndreaFx |
| quote: | Originally posted by salas
Here is one example. |
Good example salas....... and thank to Andrew, now i understand the problem ;) |
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| AndrewT |
post21 to post51 before the message got through!!!!!
Dare we let you out alone? |
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| salas |
| quote: | Originally posted by AndrewT
Salas,
ESP has asked that you refer enquirers to his site and not post extracts even if attributed. Your post isn't. |
Ah, ok. There is still the esp logo on top left of the pic, at least. |
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