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The Christiansen "DG" 300B Amplifier Build Thread - Page 3

post #31 of 639

32 lbs, just in transformers? eek.gif


You might think about reinforcing your desk. wink_face.gif

post #32 of 639
Thread Starter 

I am really phreak'd out about turning this beast on....

eek.gif  Indeed.


I need to get a set of el Cheapo cans for the testing.  I'm not going to plug in my LCD2's.   This thing puts out a bit more power than the Lyr.  10W, 60ohm's...  Perhaps I should smoke Beats with it.

post #33 of 639

From all I see you are doing an outstanding job on this build. Really very well done. I have built some amps before but nothing even close to this.

post #34 of 639
Thread Starter 
Originally Posted by HPiper View Post

From all I see you are doing an outstanding job on this build. Really very well done. I have built some amps before but nothing even close to this.

Thanks !


I have tested the filament boards and they work great.  That's a start.


I purchased Neutrik RCA and XLR jacks.



The volume pot will be the same model in the Lyr.


Processed By eBay with ImageMagick, R1.0.M1


The power receptacle has built in filtering.



I'm using 14 ga. stranded wire for the inter-connects.


Speaking of wire.  Whilst configuring the board-to-board, board to transformer, transformer to jack and transformer to volume pot inter-connects, it dawned on me that it’s all 14 – 18 gauge wire.  So.. what’s the point of fancy silver Litz headphone cables if the last 6 inches to the output transformer is vanilla, 14 gauge, stranded copper wire?  That’s what the leads are that come out of the transformers.  (see black grommets)  


Granted, a design like the Schiit Lyr has everything mounted on the PCB.  Transformers, volume pot, and jacks.  There is no wire inside the Lyr enclosure.  But that’s not the case with designs that have external transformers like this one.  Perhaps that’s where the silver wire wound transformers come in.  Just say’n.





I contacted Brent Jesse and I will order a set of matched JJ 300B valves.

He has a set of WE co's for $3,000 each. eek.gif Those along with  Jack's silver wire wound output transformers will have to wait... and wait.


The 6N6P's are quite affordable. (Yea !)  I can also swap resistors and use ECC99's.  Down the road, I'll ask Tom if he can come up with a board mod to support ECC88's style receiving valves.

Edited by sceleratus - 6/1/13 at 11:25am
post #35 of 639
Originally Posted by sceleratus View Post


He has a set of WE co's for $3,000 each. eek.gif 


Good Lord,  you could buy a used Hyundai at that price. 


Look into the Full Music tubes as well my friend says they are great budget tubes.

post #36 of 639
Thread Starter 

Found some 6N6P's

Straight from a Soviet missile silo.

8 NOS valves.  $22

We will see if I got what I paid for.  All I want is 2 good ones.


Here's the volume design....  I'm stoked by it.



post #37 of 639
Thread Starter 

300B Status:


All the boards are built.


6.3V and 5V filament boards have been tested.

Those and the Maida board are the hardest because they have surface mount components.  The PSU and Driver board are largely thru-hole. Today I fab’d a small copper heat sink for the PSU board.


I am working on attaching the large aluminum heat sink to the high voltage Maida regulator.  It will stick out the back of the enclosure.  This will be though for me because there are 2 sets of 4 hole patterns that have to be precisely drilled for mounting.  My personal best for holes in a row is 3.


I picked up a .09" 24" x 24" piece of silicon bronze for the top panel. (Nickel plate was too difficult)  Next week I will drop it off to be water cut again because of my lack of precise drilling.


The following weekend I will affix the boards to the top panel using stand-offs and make the wiring harness.  Then testing without the cabinet....


Example heat sink:

I need to drill and tap holes on the perimeter of the HS for mounting.4 







**6N6P update:

Remember the great deal I got for 8 6N6P Valves ?

I forgot one small thing.  They are in Russia....

I don't think that they will be here next week.... maybe next month.


So the great deal isn't such a great deal because I HAVE TO BUY 2 MORE !!!!!

post #38 of 639
Thread Starter 

Design Note:


For those folks that troll the “Schiit Lyr, Tube Rolling Thread”, there was a discussion 50 pages or so back about the lack of a power switch in the front of a Lyr.  And, how it is inconvenient to have to reach back and flip the power toggle.


Why did Schiit do this? One reason bantered about was running high voltage mains across the board to the front.  Well fear not!  The Damn Good 300B has a power switch in the front, and high voltage doesn’t go from front to back. How?


The DG 300B will employ a SS DPST Relay.  A 3 VDC contact closure will switch the mains.  Front Switch, Low Voltage.  Since it’s solid state relay there are no coil magnetics to worry about either.






post #39 of 639
Thread Starter 

Today I mounted the Maida regulator to the heat sink.  It took 7 holes to get 5.  In my calculations for a 3mm tap I forgot to take into consideration the run-out on my drill press.  That’s about 1mm, or Kansas.  I never learn.


I still have to drill and tap the perimeter mounting holes but they are more forgiving.  Still, I’ve had enough with the drill press for one day.  The photo 2 posts up is an example.  This is mine:



post #40 of 639
Thread Starter 

Met with my cabinet friend today.

The traditional recessed panel, humidor in the study room "look" is out.  Replaced with a very different concept, not the safest choice....  It will be love it or hate it.... I'm stoked.

I'm keeping it under wraps until make or break.

post #41 of 639
Thread Starter 

There’s only one vote cast on the poll.

Come On!


I’m wiring the boards for the smoke test tomorrow. 

I don’t have the valves yet, but I’m going to light it up anyway.



post #42 of 639

Considering all the money, time and effort you spent on this thing it had better work!! If it were me I'd probably have a break down if it blew up in front of me.

post #43 of 639

Good luck man. Never give up. Looks like a champ!

post #44 of 639
Thread Starter 

I forgot to order fuses.



post #45 of 639
Thread Starter 

Everything is here.

Fuses, valves, sockets.


I've been wiring up the headphone jack, the input jacks, and the mains.

Those will be complete in 20 minutes.  I simple have to tin 5 wires and secure them.


I wasn't expecting the 6N6P's (from Russia) the 300B's (from Brent)  and the 300B sockets from, where else,... China.


It will take me a bit to terminate the sockets.

Then triple check,

Then clear the desk.


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