• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

6EM7 / 2A3 build

SS904

SS904

AK Subscriber
Subscriber
Slow start to this, but not in a rush anyway. I finished the chassis and have had the top plate, built using Front Panel Express, for a while. Some time away from work this week and next finally gets me moving on it.

Nothing complicated. AC heaters with balance pots. Mix of turret board (for the power supply), tag strips and some point to point. The only diversion from safe and simple is I am adopting THD+N's 6EM7 driver discussed here: https://audiokarma.org/forums/index.php?threads/driver-circuit-for-dht.1015738/#post-16074201

I have a pair of JJ 2A3-40, EHX 2A3 and a pair of new testing RCAs. Will build for normal 2A3, not the 2A3-40.

Rough schematics. Will do them neatly after everything is tweaked.
My 6EM7_2A3 schematic.jpg
My 6EM7_2A3 power supply schematic.jpg

Few from the chassis build and mock-up.
IMG_2021.jpg
IMG_2041.jpg
IMG_2090.jpgIMG_2093.jpg
 
Register to hide this ad
SS904 said:
Slow start to this, but not in a rush anyway. I finished the chassis and have had the top plate, built using Front Panel Express, for a while. Some time away from work this week and next finally gets me moving on it.

Nothing complicated. AC heaters with balance pots. Mix of turret board (for the power supply), tag strips and some point to point. The only diversion from safe and simple is I am adopting THD+N's 6EM7 driver discussed here: https://audiokarma.org/forums/index.php?threads/driver-circuit-for-dht.1015738/#post-16074201

I have a pair of JJ 2A3-40, EHX 2A3 and a pair of new testing RCAs. Will build for normal 2A3, not the 2A3-40.

Rough schematics. Will do them neatly after everything is tweaked.
View attachment 3392968
View attachment 3392967

Few from the chassis build and mock-up.
View attachment 3392971
View attachment 3392972
View attachment 3392973View attachment 3392974
Click to expand...
How do you do the printing and tube diagram logo on chassis?
 
MickeySmile said:
How do you do the printing and tube diagram logo on chassis?
Click to expand...
I went to site called front panel express. You download their editing tools and design what you want. Small learning curve if you've never used tools like this, but not hard at all. You order and pay for the panel right from the app. The Triode graphic is my own making. It's nothing more than an arranged grouping of a circle and a bunch of small lines drawn in to the tube symbol.
https://www.frontpanelexpress.com/p...6wTJp2Dzmpggl_HE2zdywhGbsEeYaArlHEALw_wcB#typ

I've used them to make front panels for my Dynaco PAS chassis too. They do great work.
 
SS904 said:
I went to site called front panel express. You download their editing tools and design what you want. Small learning curve if you've never used tools like this, but not hard at all. You order and pay for the panel right from the app. The Triode graphic is my own making. It's nothing more than an arranged grouping of a circle and a bunch of small lines drawn in to the tube symbol.
https://www.frontpanelexpress.com/p...6wTJp2Dzmpggl_HE2zdywhGbsEeYaArlHEALw_wcB#typ

I've used them to make front panels for my Dynaco PAS chassis too. They do great work.
Click to expand...
Thank you! following on your build!
 
Front Panel Express does great work. I used them years ago for the power supply plates in my 211 monos. That's a very nice layout on your amps!

Jack
 
Front panel express does do nice work. Even the colored brushed aluminium face plates look nice. Awhile back some here on AK was having Marantz face plates made. Silver, black, blue, and red. The red and black with white lettering were my favorites. They'll even engrave the lettering if requested.
Front Panel Express made the face plate for my FM3 tuner.
 

Attachments

  • 20220211_113047.jpg
    20220211_113047.jpg
    42 KB · Views: 32
SS904 said:
Whoa! That's a lot of work on that panel! Looks fantastic!
Click to expand...
Thanks, didn't mean to hijack the thread on your build, but wanted to put in a plug seeing the great work on your top plate. The bottom line is they can basically do anything you tell them to, but you have to tell them exactly what to do (in the form of your design). It took many hours to get the design done properly, being a complicated piece, but what came back was worth it to me.

Looking forward to more on your build!
 
Just a note on FPE for the benefit of members contemplating using them for the first time - the company cuts these panels from sheet stock that is pre-anodized. That means the edges are raw aluminum. Not only do the edges look different from the rest of the panel, they're much more susceptible to physical damage like scratching, because these areas lack the hard oxide coating. This is why the panels I build for my projects (which usually have exposed edges) are anodized last, after all the other work. Allen Wright (RIP) used to complain about this aspect of FPE's panels, and I don't know if he ever found a solution to the problem.
 
Last edited:
TriodeLuvr said:
Just a note on FPE for the benefit of members contemplating using them for the first time - the company cuts these panels from sheet stock that is pre-anodized. That means the edges are raw aluminum. Not only do the edges look different from the rest of the panel, they're much more susceptible to physical damage like scratching, because these areas lack the hard oxide coating. This is why the panels I build for my projects (which usually have exposed edges) are anodized last, after all the other work. Allen Wright (RIP) used to complain about this aspect of FPE's panels, and I don't know if he ever found a solution to the problem.
Click to expand...
Fair point and something to note. The company offers edge treatments for a modest up charge. On my PAS panels, I chose edge sanding to clean up the look. The panel is only 1.5MM thick, so the visual is pretty low impact. Even if I chose a finish other than natural aluminum, I think I could work with the silver edge but that would be project dependent. For this top plate I did not choose the edge sanding as the edge is not exposed. Also the material is 3MM thick to support the heavy transformers. If the edge was exposed, It might be a harder aesthetic to deal with. They also offer powder coating which I believe is done after the cuts. Pricey though!
Sanded.
IMG_2157.jpg
Not sanded.
IMG_2156.jpg

Not much progress today. Went to the hardware store to find the remaining stainless steel hardware needed and finished prepping the transformers by insulating and tucking away all the unused taps.
 
Those Hammond 1630SEA's should sound great. My first pair of SE OPT's were 1627's (from 1999) and I still love them.
 
You must log in or register to reply here.
Back
Top Bottom