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Old 19th July 2005, 01:53 PM   #101
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Default Re: Using Revision A boards for Rev C

Quote:
Originally posted by Panelhead

Russ,
Looking it over it looks like there are 4 resisitors and four capacitors added per channel. I hate to do it, but it should be fairly easy to "hillbilly rig" these 16 components to the circuit board. George

Yes, I understand you can go that route, and really it should work fine. But I really have a couple of reasons for my PCB layout.

1) I want 5 channels in one enclosure for 5.1 listening.
2) I want a seperate PS from the amp board so that I can easily swap amp sections if that is all that has changed.
3) I don't really like "hillbilly rigging" if I don't have to.

Yes those PE trafos woprk great! I have been listening to my standard NIGC with one for the better part of a week! What a steal! Those are perfect gainclone trafos.

Here is my latest iteration with the additon of LM7812 and LM7912 voltage regulators on board for the opamps.

Not finished quite yet as I still do not have some bypass caps in place for the VRs. Also I will add more pads for larger input caps.

Cheers!
Russ
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Old 19th July 2005, 02:02 PM   #102
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Default New Boards

Russ,
I will wait on building then myself. I do not like having 16 components hanging off the board either. This will triple the chance of bad or shorted connections.
Do you think you will have Rev 3 boards available for sale by sometime next month?


George
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Old 19th July 2005, 02:06 PM   #103
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Default Re: New Boards

Quote:
Originally posted by Panelhead
Russ,
I will wait on building then myself. I do not like having 16 components hanging off the board either. This will triple the chance of bad or shorted connections.
Do you think you will have Rev 3 boards available for sale by sometime next month?


George

If Mauro blesses the design I would be glad to offer some boards for sale as soon as I can test the board, which would likely be in the next month or so as you say.

In the meantime, there is certainly nothing wrong with the REV "A" circuit. It sounds simply stunning.

Cheers!
Russ
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Old 19th July 2005, 03:32 PM   #104
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Here is what I have so far

PCB:
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Old 19th July 2005, 03:34 PM   #105
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Schematic: I know its a mess, I will clean it up when I get a chance.
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Old 19th July 2005, 04:09 PM   #106
Mark Kravchenko --- www.kravchenko-audio.com
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Thumbs up If this is your second time designing a board I stand in AWE!

Getting pretty slick SIR!

Mark
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Old 19th July 2005, 04:19 PM   #107
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Thanks Mark,

I have designed a few more circuits (preamps and headphone amps) in the last few weeks, but this is only my second serious chipamp layout.

I hope Mauro does not think it stinks.

You are very kind.

Russ
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Old 19th July 2005, 05:12 PM   #108
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Alas, it appears there are a few problems with my layout.

1) Lm7812/7912 may not be suitable as the input voltage would be close to its maximum. So I will redesign using the RCZ net as Mauro did.

2) I need to include some sort of soft start/delay circuit to elminate the turn on thump.

3) Grounding may be somewhat iffy. Still looking at that.
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Old 19th July 2005, 05:24 PM   #109
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Quote:
Originally posted by Russ White

1) Lm7812/7912 may not be suitable as the input voltage would be close to its maximum. So I will redesign using the RCZ net as Mauro did.

2) I need to include some sort of soft start/delay circuit to elminate the turn on thump.

Would a larger value cap on the mute release pin suffice?

edit: After re-examining the PCB, would any cap on the mute release suffice?

Edit 2: After looking at the LM318 data sheets, the supply voltages are good @ +/- 12VDC. The input voltage is refering to signal input not pwr supply input.
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Old 19th July 2005, 05:45 PM   #110
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Quote:
Originally posted by rabstg

Would a larger value cap on the mute release pin suffice?

edit: After re-examining the PCB, would any cap on the mute release suffice?

Edit 2: After looking at the LM318 data sheets, the supply voltages are good @ +/- 12VDC. The input voltage is refering to signal input not pwr supply input.
I am not sure if the mute cap would work or not.... It just might.

I was referring to the max input voltage on the LM7812/7912 which is 35V. Which happens to be just about what the rails would be at.

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