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The Christiansen "DG" 300B Amplifier Build Thread - Page 43

post #631 of 639
Thread Starter 

Festool Domino 500 arrived and the music room shelf is complete. Soon l will tackle the amp cabinet.

I came up with a very unique design based on an iconic shape.  I hope I can pull it off.  It will be wild.

The room will be painted a different color as well.

 

 

post #632 of 639
Thread Starter 

Been gone for a while.

 

During which I made a set of Bob Brines M10-A10 Mass Loaded Transmission line speakers using the MarkAudio Alpair 10M driver.

 

I am very pleased with how they sound with the 300B.  I built them on a leaf-of-faith and I’m very surprised with the results.  The bass far exceeded my expectations.  Naturally I’m not going around listening to other speakers.  Ignorance is bliss and easy on the wallet.

 

Currently building a preamp and phono preamp.

 

 

 

 

 

 

 

 

 

post #633 of 639

Hi Sceleratus,

 

I like very much what you have done here. Using 300B in SET seems to be ultimate solution for a headphone amp. I am trying to read through your posts here but somewhere I've got stuck .... What I am interested is to find out what changes to the original scheme of Damn Good 300B you've made in order to make a headphone amp ? Did you used the original DG PCBs and then did some modifications ?

 

I am thinking of going the same path you did but I would like to find out first what I can expect in terms of already existing DG PCBs ... ?

post #634 of 639

Not Sceleratus, but I'm pretty confident he (and Tom, the designer provider of this information) wouldn't mind. I've built the same amp, and Sceleratus and I but implemented the same basic 'LPAD' circuit that Tom provided. I've attached it below. This allows us to switch between speaker taps and headphone out. I've been running mine with Mills resistors, but just yesterday rolled in Path Audio resistors. The mills sounded great, but these PA resistors are ridiculous. Clean, smooth, fast, better macro / micro detail (less phase shift / smear) and better separation. Not cheap, but they're not coming out.

 

post #635 of 639
Thread Starter 
Quote:
Originally Posted by DejanM View Post
 

Hi Sceleratus,

 

I like very much what you have done here. Using 300B in SET seems to be ultimate solution for a headphone amp. I am trying to read through your posts here but somewhere I've got stuck .... What I am interested is to find out what changes to the original scheme of Damn Good 300B you've made in order to make a headphone amp ? Did you used the original DG PCBs and then did some modifications ?

 

I am thinking of going the same path you did but I would like to find out first what I can expect in terms of already existing DG PCBs ... ?


Hi Dejan,

Misterrogers is spot on.  Has nothing to do with the PCB.  It's all about the output transformers.  The windings and resistor values you specify to match your headphone and speaker specs.  If you only want to use HP's have the OPT's made to match.  Mine are  Audeze LCD2 and  MTL speakers with Alpair drivers.

 

I'm building a case for Misterrogers DG300B. Why?   Cuz I didn't build my case and I wanted to see if I could build a better one.  Unfinished woodworking business.  Being an insufferable show-off here's where it stands.  We are finalizing the top and back plates.  We've also come up with some cool tricks which will be revealed if they actually work. :wink:  Gotta update my other thread.

 

 

 

post #636 of 639

^ What he said :-)

 

Glad you mentioned the case - didn't want to 'out' your efforts; cause if I was reading this, building this amp, and you weren't making it for me.... I'd be dogging ya! 


Edited by Misterrogers - 2/11/17 at 8:10am
post #637 of 639

So if I understand you correctly guys, no changes to the original PCBs and component values except for the output transformer ... is that correct ?

 

What do you thing about Lundahl LL2765 as an output transformer ?

 

http://www.lundahl.se/wp-content/uploads/datasheets/2765.pdf

post #638 of 639

There are a handful of things that can be swapped or upgraded (output resistors / caps come to mind). You don't need to (the amp is well designed, and the BOM is solid), but you can if you want to squeeze more out of it. I went with custom Silk power and output transformers - c-core. Don't have experience with LL2765.


Edited by Misterrogers - 2/11/17 at 8:10am
post #639 of 639
Quote:
Originally Posted by DejanM View Post
 

So if I understand you correctly guys, no changes to the original PCBs and component values except for the output transformer ... is that correct ?

 

 

Correct. 

 

If you use the circuit shown in Post #634, you won't need to change the output transformer either. Just build according to the instructions and you'll be fine.

 

Tom

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