Gainclone building thread based on BrianGT's boards

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tg3 said:
Can't build anything until my Cardas group order comes in... :(

That is what I said about my Aleph projects... and the Cardas posts came in, and are still sitting on the shelf.

I also have piles of heatsinks scattered all over my apartment... (8+8+4+4=24 heatsinks waiting to be used)

If anyone hasn't seen my gainclone build pictures, please visit my gallery:
http://brian.darg.net/gallery/nigc-kit
It should be fairly thorough. These pictures will be in the manual, along with schematics and descriptions.

Sorry for the delay in the manual, but I am still working hard to get all the kits done. Hopefully I should get most of the remaining kits done tonight and ready for Meredith to start shipping out tommorrow.

--
Brian
 
BrianGT said:



If anyone hasn't seen my gainclone build pictures, please visit my gallery:
http://brian.darg.net/gallery/nigc-kit
It should be fairly thorough. These pictures will be in the manual, along with schematics and descriptions.

Sorry for the delay in the manual, but I am still working hard to get all the kits done. Hopefully I should get most of the remaining kits done tonight and ready for Meredith to start shipping out tommorrow.

--
Brian


Brian:

Excuse the n00b q, Why is the precision resistor snugged up to the LM3875?

speaker
 
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speaker said:
Brian:

Excuse the n00b q, Why is the precision resistor snugged up to the LM3875?

The resistor is the negative feedback resistor. In order to obtain the best performance from the LM3875, the feedback look must be as short as possible. This component has the most effect on the amplifier's performance.

This resistor can be soldered right in front of the lm3875, or on the bottom side of the pcb.

--
Brian
 
BrianGT said:


The resistor is the negative feedback resistor. In order to obtain the best performance from the LM3875, the feedback look must be as short as possible. This component has the most effect on the amplifier's performance.

This resistor can be soldered right in front of the lm3875, or on the bottom side of the pcb.

--
Brian


Ah, that makes complete sense now and is an elegant solution. It appeared that you wanted it to track thermally with the output device and I could not figure why.

speaker
 
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speaker said:



Ah, that makes complete sense now and is an elegant solution. It appeared that you wanted it to track thermally with the output device and I could not figure why.

speaker

I like the appearance with the resistor in the front the best.

Another option, if you are using the T package along with the thick thermal insulator, would be to place the resistor on the back side of the LM3875T, and you can probably even get it a bit closer to the actual leads. This is what I did on my prototype.

I do still like it best as pictured below.

--
Brian
 

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Re: Fuse

vsr123 said:
I think a 1.5A to 2A fuse should be enough. Not sure if you need a slow blow type though since the inrush current should be small. If you read other threads the general comment is to keep trying different fuses until they stop blowing! :)

cheers
vsr


that's just what i did and i settled with an 1.5 amp sloblo fuse for use with a 225 VA toroid
 
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Re: Re: Fuse

matjans said:

that's just what i did and i settled with an 1.5 amp sloblo fuse for use with a 225 VA toroid

I am currently using a 2A fuse in mine. I had a 3A fuse in my previous unit. Neither of them has ever blown (both slowblo), so 2A should be fine. I haven't tried lower than 2A.

I am curious to see what the 2 channel Bridgeclone that I am looking at building will require (12 boards total on a 1kVA transformer)..... I am hoping that the 1kVA is enough for both channels, as I am not buying another transformer.

--
Brian
 
BrianGT said:


That is what I said about my Aleph projects... and the Cardas posts came in, and are still sitting on the shelf.

I also have piles of heatsinks scattered all over my apartment... (8+8+4+4=24 heatsinks waiting to be used)


...And yet he still won't sell me any of the nice ones. He must be must be saving them for another imaginary project ;).
 
BrianGT said:


I am using 2x24vac and Peter is using 2x22vac.

The datasheet specifies |-V| + |+V| to be in the range of 20vdc to 84vdc.

(just realized that this is my 2000th post)

--
Brian

Well, then shouldn't I be able to use the ~30-0-30 transformer I pulled out of that old yamaha? It would certainly be a little close to the limits of the SOA, but I like living on the edge, hehe. In fact, I've run my computer's CPU at over two volts (>25% increase over normal) for overclocking and it survived. It's also a lot more expensive than an LM3875.

Oh yeah, and congratulations on the 2000th post.
 
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