Eros mods

[tttubes]

Just wondering what mods you have done to your eros.

Thanks Jim

Here's what what I've done replaced the resisters in the signal path with naked vishays I had audio note paper in oil copper caps in but felt there was something missing.

So I picked up some amp ohm copper foil paper and oil caps and I'm loving them even though they only have about 12hrs on them.

I also wired my interconnects directly to the output caps.   

[Grainger49]

Paully has an adapter that allows him to use a different Pentode as the input tube.  He will surely post.

[Paully]

We have just done pin-out changes for different tube types, as well as the usual cap upgrades.  We tried EF40 (multiple versions) which I will admit didn't float my boat.  We also redid the pin-outs for a 6BR7.  While we changed back to EF86 I was interested enough to buy some adapters to be more easily able to compare.  Having put the 6BR7 in I have been so happy I haven't bothered to change back.  I posted on this a week or two ago.  Other than that I haven't seen many people doing much in the way of true modding like they would do for a Foreplay II.  I think this thing has a lot of bells and whistles as it is.  But I will be interested to see what others have done.

[Grainger49]

The right and left B+ are regulated individually so upgraded power supply caps have a low impact and there is no need for an RRSF.  The heaters are regulated DC, both plates have a CCS feeding them, there are few places for improvement.

The output capacitors, 1uF in the kit but 0.47 in the design, could be swapped.  Paul Birkeland mentioned that the plate load resistors could be upgraded.  Those are 47k 2W for the 6DJ8 and 75k 1/2W for the EF86.  There is a thread on this too.

PJ, Doc and the crew have pretty much tweaked this one out to start with.

[tttubes]

Wow I have about 30hrs on the amp ohm copper foil paper in oil caps and wow they sound great big sound stage and very open and natural sound and there not even broken in yet.

[Brillo]

I swapped out the output caps shortly after the initial build with very positive results.  I just finished installing 47k 2W resistors for the 6DJ8, and put in some Shinkoh tantalum 75k 1/2 W resistors for the ef86.  As soon as my wife is done watching her corny movie, I'll check out the sound.

[Brillo]

Just a follow-on of resistor upgrades performed: I think this helped bring things into focus a bit, but not overwhelming.  Not a bad swap; relatively inexpensive.  Switching out the 6922 for a good 7308 made a significant improvement.  I would recommend that change certainly.

I'd be interested in learning what other mods may be helpful.  Also, I'd like to try the 6BR7 that Paully mentions.  Are the pin-out changes described somewhere in another post? 

[Paully]

We didn't ever put down what goes where in another post.  This is what I have when I was writing it up for the guy to manufacture a tube socket adapter.  Personally, I would seriously consider that route, $27.50 plus shipping and a lot easier to switch back for comparison.  But if you want to do it yourself, and you are a Bottlehead after all, this is what I have, but I think you will want to reverse it (Pin 9 goes to Pin 2 of the 6BR7) and go double check the 6BR7 to EF86 schematic.  It is actually pretty easy to do.  Grainger, can you please verify?

Also, Langrex has 6BR7 cheap.

6BR7 socket      goes to    EF86 Pin
1-Not used
 
2                                    Pin 9
 
3                                    Pin 3
 
4                                    Pin 4
 
5                                    Pin 5
 
6                                    Pin 2 and Pin 7
 
7                                    Pin 6
 
8                                    Pin 1
 
9                                    Pin 8

[Doc B.]

FWIW I would be inclined to rewire the socket rather than using an adapter, so that you can still use the tube shields. Shawn has been running 6BR7s in his Eros phono and liking them.

[Grainger49]

Paully is below grade with his Eros so it is somewhat shielded.  I agree with the pin numbers.

[Paully]

I deleted my earlier post as I am remembering that the 6BR7 mod was probably the easiest of the tube swaps we tried.  Most of the wires stay in the same spot, so it may be worth doing it the old fashioned way not only for the shielding (which I have never needed to use, so that wouldn't have occurred to me) but just because it is easy enough that the money for the adapters may not be worth it to you.  It was for me, I wanted to be able to easily compare back and forth as the spirit moved me.  But moving the wires around is relatively easy.

[Brillo]

Sweet!  Thanks all.  Finally something to solder (my favorite smell (next to the forest of Ontario)). 

[Brillo]

The pin relationships seem straight forward except for 2&7 (ef86) to pin 6 (6BR7).   In the Eros Manual, the black wire to ground runs through pin 2, then the center pin, into pin 7.  To reconfigure for the 6BR7, would I still route that wire through the center pin and connect to pin 6?

As usual, thanks all for the guidance and assistance. 

[Paully]

I am looking at the tube socket adapter Grainger and I built.  We routed Pin 6 of the 6BR7 to both pin 7 and 2 of the EF86.  That would mean we were routing pin 6 to ground (twice, just to be sure)  So I think yes, you are right, just route pin 6 to the center pin for the for the 6BR7.

[Grainger49]

I do remember the jumper from pin 7 to pin 2 for ground.  Wherever you decide to go to ground will work fine.