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Commercial Gainclone kit- building instructions

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#663
mattcalf said:
I want to add an input selector such as the one cyxg has built into his GC amp. I've found a few that look similar and don't clearly know what the specs mean and the specs required are.

I'd like 3 inputs, what kind of Rotary Switch should I go for?

Also for hookup wire, would this be suitable?
Click to expand...

Hi,Matt

I use Rotary Wafer 3 Pole 4 Position, but i just use 2 pole(right/left)and 3 position.

About wire, the silver wire is better. i don't know how can i find it in Australir.
 

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#665
cyxg said:


Hi,Matt

I use Rotary Wafer 3 Pole 4 Position, but i just use 2 pole(right/left)and 3 position.
Click to expand...

If it's not too much trouble could you email/pm/post a few photos highlighting your hookup to the Rotary Switch?

Thanks,
Matt. 😀

tiglitosa said:


Hi
I dont know about Australia but in Hong kong there is a good source


check this

I have tried them and they are fast and reliable.

Cheers

Nick
Click to expand...


Thanks, but I've found some decent enameled copper that I think I'll use.🙂
 
#672
mattcalf said:
Thanks, was hoping for a closer shot of actual wiring but this should help. 🙂

Another question:
With the pot, I've bought an ALPS 50k. What's will be the difference between using a 10k, 25k, and 50k?

Cheers,
Matt.
Click to expand...


50k = more attenuation, more silent in full ccw rotation i think since pots are logarithmic.

Nick
 
#677
Peter Daniel said:
It's not possible to implement itt without resistors. Just use the size and color you like the most, adjust resistor accordingly to desired brightness: http://www.diyaudio.com/forums/showthread.php?postid=1517911#post1517911
Click to expand...
Thanks Peter
I have read that post but I still fail to understand how you are getting to the proper resistor value. For example if I am working with dual 24V rails and am trying to use a standard 3V LED. What resistor would cause the LED to operate at 3V? Is there a simple calculation for this?
 
#678
Peter Daniel said:
I wouldn't think so, too much copper is not a good idea either. I like to combine: copper for heat spreadign (and weight), aluminum for dissipation, that's how it's done in Patek amp: http://audiosector.com/chassis_patek2_amp.shtml
Click to expand...

Peter,
thanx for your responses.!

Yes i have seen the patek and its really very very neat !
But in my case the chip is mounted on a 12,8x12,8 1mm copper plate and i think i will add underneath a 12,8x12,8 4mm solid aluminum.

Will this be enough for heatsink? 🙄

And is there an online place to buy solid alimunum 12,8cm x12,8cm of lets say 1,2 cm thickness? I see you got some very good aluminum blocks.


🙂
 
#679
Mike-Toronto said:
I still fail to understand how you are getting to the proper resistor value. For example if I am working with dual 24V rails and am trying to use a standard 3V LED. What resistor would cause the LED to operate at 3V? Is there a simple calculation for this?
Click to expand...
Hi,
3V is not a standard LED, it may be a blue one.

First subtract the LED voltage from your supply voltage. Either 24V-3V or 48V-3V.

Look up the datasheet for the LED and decide roughly what current you would like to pass through the LED. More current = brighter, less current = dimmer, too much current = overheating or :flame:.
Take the remaining voltage and your desired current and apply ohms law. I = V / R , rearranged as R = V / I

Let's use the 48V supply and 4mA as an example.
V = 48 - 3 = 45
I = 4 /1000 = 0.004
R = 45 / 0.004 = 11250ohms.
Use 11k
the actual current is given by I = V / R = 45 / 11k = 4.1mA.

Try this and see how bright it is. Then decide if you want/need more or less current.
 
#680
tiglitosa said:

But in my case the chip is mounted on a 12,8x12,8 1mm copper plate and i think i will add underneath a 12,8x12,8 4mm solid aluminum.

Will this be enough for heatsink? 🙄

And is there an online place to buy solid alimunum 12,8cm x12,8cm of lets say 1,2 cm thickness? I see you got some very good aluminum blocks.


🙂
Click to expand...

It might be a good idea to add aluminum plate underneath copper sheet (1mm is too thin to call it a plate) to reinforce it.

I can't say if it's going to be enough for heat dissipation as that will depend on type of music, volume level and type of speakers. In some cases it could be enough, but not when you really push the amp.

I would certainly consider some additional aluminum elements to increase the dissipating surface, but then agaun you can always do it later.
 
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