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Old 16th August 2010, 09:34 PM   #551
udailey is offline udailey  United States
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Ah, ok I see now what you meant. When you said to take a cord to chassis I thought you meant as some sort of grounding.
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Old 17th August 2010, 12:58 AM   #552
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Originally Posted by troystg View Post
My comment was he should NOT being using speaker cord for mains power. See the speaker wire exiting the rear panel at the lower, center spot...
I do agree completely.

Speaker cable isn't safe for mains voltage...

The best thing is to mount an IEC inlet, and connect PGND to safety ground, even if it's disconnected... IMHO

When Vlad will have a safety ground his amp will be ready.
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Old 17th August 2010, 11:58 AM   #553
vlad712 is offline vlad712  Moldova
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Default few steps to improve my amp

Thanks for the power-discussion. When listening to several experienced builders the the transparency enters my brain. nice medicine.
It's clear for me that I should add some hardware, so please recommend the brand or DIY source for:
- good mains cable
- mains fuse (I thought it is superfluous accessory decreasing the sound quality)

Also what solution could helps to eliminate the hum/noise and woofer bang when switch on?

I think when I have safety earth in my flat I'll connect PGND to it, but I can't do it right now. and I want to listen to my new amp.
If I connect the on-board PGND to the case right now without earthing - is it good or bad idea?

Vlad

Last edited by vlad712; 17th August 2010 at 12:13 PM. Reason: adding details and the question
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Old 17th August 2010, 12:24 PM   #554
AndrewT is offline AndrewT  Scotland
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Originally Posted by vlad712 View Post
......If I connect the on-board PGND to the case right now without earthing - is it good or bad idea?
this is equivalent to building a double insulated amplifier without the double insulation and without the testing to prove it is safe to connect to the mains.

I cannot advise that a power amplifier be connected to a mains wiring system that does not have Protective Earth as the third wire.
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Old 17th August 2010, 12:36 PM   #555
vlad712 is offline vlad712  Moldova
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Default power connections

I'm thinking to organize my system' (cdp, pre, poweramp) power connections with Neutrick powerCONs (thanks troy).

1st way: I'll add powercons to all my devices and connect the power in chain, i.e input power from the wall socket firstly goes to cdp' powercon-IN, then from its powercon-OUT to pre, and finally from pre to poweramp.

2nd way: I'll build the splitter with powercon-OUTs which will be connected to inwall socket. All devices (supplied with powercon-INs) will be powered from the splitter with separate wires.

Please advise
- which way is better ?
- does powercon-based system sound worse then IEC ?

Vlad

Last edited by vlad712; 17th August 2010 at 12:55 PM. Reason: correct spelling
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Old 17th August 2010, 08:13 PM   #556
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Default Thermal Pad

Is an aluminum oxide thermal pad superior to mica? They're only 50 cents each and I have a Mouser order going anyway.

4170G Aavid Thermalloy Heatsinks

TIA,

rick
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Old 18th August 2010, 10:12 AM   #557
AndrewT is offline AndrewT  Scotland
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possibly, it depends on the relative thicknesses and flatness of the two types of insulator.
1thou/mil or 0.001inch/0.025mm is hard to match never mind improve on.
Both types need thermal compound at both interfaces to eliminate air from the thermal path.
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Old 20th August 2010, 08:35 PM   #558
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Default LM318 socket

Is it correct that there is no directionality to the LM318 socket? Half of mine face one way and the other are opposite. As long as I correctly insert the IC in the appropriate orientation, then all is well? I was reading on another project and the author stated to be sure and get the socket in the correct orientation and now I need to verify before applying power.

TIA,

rick
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Old 20th August 2010, 09:02 PM   #559
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Quote:
Originally Posted by Lazarus500 View Post
Is it correct that there is no directionality to the LM318 socket?
Not sure if I understand the question correctly, but it sure is directional. Pin 1 is right below the notch on the socket, and Pin 1 on the IC (marked by a dot) has to go into Pin 1 of the socket - it can't go into Pin 5.

The silkscreen also shows which way the notch in the socket has to face when the socket is inserted.
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Old 20th August 2010, 09:52 PM   #560
troystg is offline troystg  United States
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The sockets have an orientation marker but it is purely cosmetic. If the socket was soldered in backwards but the opamp is installed in the correct orientation it will work. However if the opamp is removed there is a high probability of the replacement being installed incorrectly.
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