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EHHA Rev A - Interest Thread - Page 8

post #106 of 1671

If you want to go all-out, consider having both the heater and split-supply PCBs attached to the amp PCB.  It would offer quite a bit of flexibility but it would certainly be most expensive.

post #107 of 1671

down with more expenses! 

post #108 of 1671
Quote:
Originally Posted by ujamerstand View Post

down with more expenses! 


X2

 

Still like the idea of each board having its own PS and the channel separation that comes from each having its own reg section. It is easy enough to find a heater supply or use AC heaters and this board setup makes it easier to build either 2, 3 or 4 channel builds.

post #109 of 1671

Count me in for a set.  How much would the extra expense be? It would be nice to have the flexibility.

post #110 of 1671
Quote:
Originally Posted by Forte View Post




X2

 

Still like the idea of each board having its own PS and the channel separation that comes from each having its own reg section. It is easy enough to find a heater supply or use AC heaters and this board setup makes it easier to build either 2, 3 or 4 channel builds.





I agree. Sometimes too much flexibility destroys the simple beauty of the implementation. I say keep the split supplies and don't worry so much about the heater supply. Unless you can jam both power supplies on a single board, I see no real advantage.

I think of it this way, if you are financially challenged, just use AC on the heaters. It does not get any simpler, easier or cheaper as it is just a transformer. If you want to upgrade to DC, there are lots of boards out there that can do it, including a homemade perfboard.

I think the DC heater muddies the water at this point.
post #111 of 1671
Quote:
Originally Posted by FallenAngel View Post


If you want to go all-out, consider having both the heater and split-supply PCBs attached to the amp PCB.  It would offer quite a bit of flexibility but it would certainly be most expensive.





I just re-read this post. This might not be a bad idea. You could snap off the heater supplies for better location in the chassis and still have the split rail supplies for each board "at the back" .

This would also limit it to one board to produce. Each board has an amp channel, a split-rail suplly at one end and a split dc heater suplly on the other. Each board would have everything you need to build an amp channel. You could even make the DC heater supply 6.3V as you would have one for each channel. Would make a clean kit as the board is a composite, yet modular representation of all the PCB you would need.

I like it. Good thinking Fallen Angel!!
post #112 of 1671
Quote:
Originally Posted by jdkJake View Post

I think the DC heater muddies the water at this point.



And why the specific need for regulated DC heater? Isn't the goal usually to just get rid of the AC?

 

You could have just a diode bridge and smoothing cap for about $5, no need for regulator or cap heatsink, very minimal board space......


Edited by Beefy - 8/19/10 at 6:34am
post #113 of 1671

Beefy's idea is very good.

 

I really like the idea of having everything for one channel on one board.

 

I'll probably get a pair of boards,  can't guarantee a quick build though...

post #114 of 1671

Beefy's idea is excellent. 

post #115 of 1671

Extend the board (on the tube) side to put a heater supply (bridge + cap), again on a small snap off segment.

 

That way, you can use the board integrated, or you could snap off the heater or rail PS or both to do an all out board with your own supplies.

post #116 of 1671

My 2 eurocents... leave the heater supply off so everybody can use what he likes best. 

All of my headphone amplifiers but two (one SS, one AC = makes 6 total ) use DC heaters either CRC or regulated.

I have gotten used to really clean DC on the heaters...

post #117 of 1671
Quote:
Originally Posted by Beefy View Post

And why the specific need for regulated DC heater? Isn't the goal usually to just get rid of the AC?

 

You could have just a diode bridge and smoothing cap for about $5, no need for regulator or cap heatsink, very minimal board space......

 

 

Unregulated DC off a bridge on a 12.6volt xformer tap yields about 16 volts dc. Wears out heater filaments unnecessarily fast.
 

post #118 of 1671
So use a 9v transformer if my math is right.
post #119 of 1671

9V transformer will be a little low unless you use Schottky diodes (which would be a good idea), 12V using normal diodes will work too, though might be a good idea to add a resistor to drop some voltage, better yet, CRC.  :)

post #120 of 1671
Quote:
Originally Posted by cobaltmute View Post

So use a 9v transformer if my math is right.


Sort of, you forgot the two diode drops. If you want exactly 12.6v unregulated you'd need a 9.9 volt xformer at the required current. There's another rub though, the actual voltage off a xformer depends on current out. Then there's the issue of line variations nationwide of about 10%. I suppose there's plenty of ways to skin the cat, but I personally would accept AC heaters or (preferably) use regulated DC. Tubes sound fine over a fairly large range of heater voltages, but running them too hot shortens tube life and too cold makes them cantankerous. I'd rather spend a couple bucks on a regulator than shorten the life of a few $10 tubes.

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