The Christiansen "DG" 300B Amplifier Build Thread

[holland]

It looks great.  The knob is definitely better.

 

[sceleratus]

Thanks.
It's an entirely different look.
I put a coat of lacquer on it last night and the grain popped.  It matches the sides now.  I am very happy.
 
EDIT:  I really like the attenuator.  The step clicks are very smooth and the sound is great.

 

[holland]

That's great.  I was just wondering about the attenuator.  To be honest, I cannot hear differences in pots, or perhaps it's just that I don't know what to listen for.

 

[sceleratus]

I'm not sure I can tell the difference either.  They are very close.  I'm just pleased that it sounds good; very clean.  I also like the tactile clicks. I was worried about that but I think I like it better than a pot.

 

[tomchr]

That's a sweet looking amp. Nice execution. Thanks for sharing your experience.
 
~Tom

 

[sceleratus]

Beauty shot with finished knob...
 
 

 

[catfish]

Quote:

That's a sweet looking amp. Nice execution. Thanks for sharing your experience.
 
~Tom

 
How much power is this estimated at,  could it handle 5W the HE-6's ?

 

[sceleratus]

Quote:

 
How much power is this estimated at,  could it handle 5W the HE-6's ?

This is the OPT specs from Jack Elliano at Electra-Print
 
 

 

[tomchr]

Quote:

How much power is this estimated at,  could it handle 5W the HE-6's ?

 
The DG 300B Amp delivers 10 W into an 8 ohm load (1 % THD). Clipping (3 % THD) happens at about 12 W. 
 
~Tom

 

[catfish]

Quote:

 
The DG 300B Amp delivers 10 W into an 8 ohm load (1 % THD). Clipping (3 % THD) happens at about 12 W. 
 
~Tom

 
This is fantastic.  My only concerns are sceleratus's comments that there is some noise.  What makes a great headphone amp is a simple test.
 
Play music on your most sensitive/efficient headphones about as loud as you like.
 
Then play a "silence" tack which is basically just digital null.   If you hear any noise it affects the SQ.  Its a better test of a headphone amp than any THD,IMD, FFT, etc.
 
I suspect this amp would pass the test with flying colors for orthos but may not for Grados and Senns,  which is fine really we all need more than one amp

 
I want to build something similar,  I really like the Madia regulator as I think it is a great step toward a black background SET.  But I am a little apprehiensive about the smps DHT heat.?

 

[tomchr]

Quote:

This is fantastic.  My only concerns are sceleratus's comments that there is some noise.  What makes a great headphone amp is a simple test.
 
I suspect this amp would pass the test with flying colors for orthos but may not for Grados and Senns,  which is fine really we all need more than one amp

 
I want to build something similar,  I really like the Madia regulator as I think it is a great step toward a black background SET.  But I am a little apprehiensive about the smps DHT heat.?

 
I seem to recall that Sceleratus reported that using differential inputs took care of the noise. It's possible there was a ground loop in his first setup...
Regardless, I have some experiments underway for using output transformers with higher turns ratio for driving headphones. This should dramatically reduce any noise. I'll be testing this with my Sennheiser HD650.
 
I understand that some people fear switchers. I'm not really sure why. I compared a linear lab supply versus a switching supply for the 300B filament supply in an earlier 300B design of mine. You can see the results here: 300B Switchmode Filament Supply. I am not able to measure any significant difference between a linear supply and my switchmode supply. But the switchers are so much easier on cost and on the thermal budget.
 
~Tom

 

[holland]

Quote:

Originally Posted by tomchr /img/forum/go_quote.gif
 
I understand that some people fear switchers. I'm not really sure why.

 
Audiophile BS, that's why.

 

[tomchr]

That is my suspicion as well. But as my measurements show (see link above), the fear is rather irrational.
 
~Tom

 

[Dubstep Girl]

So does DG stand for dubstep girl?

 

[sceleratus]

Quote:

So does DG stand for dubstep girl?

Well I guess it could.
Right now it's "Damn Good"