Birthday and Christmas present - Shunt Regulation and JJ 2a3's

[Sugar Man]

After reading other posters' great reviews for the Stereomour/JJ 2a3-40's/Blumenstein combo synergy, I pulled trigger on a pair of JJ 2a3's, and JJ ECC81 Gold-pins.  Don't want to waste a side on each driver tube, so no choice but to order up the new shunt regulation kit.  Can't wait to take great to greater.

[Doc B.]

Thanks for your order, Mike. And thanks to all of you who have patiently waited while we got this kit ready and already placed an order. I think you will all like the improvement.

[Sugar Man]

Your welcome, Dan.  I'm sure that I speak for all of us when I say how much we look forward to the well-implemented upgrades to an already great product.  Bravo to you and the Bottlehead team.

[Paul Joppa]

....  Don't want to waste a side on each driver tube, so no choice but to order up the new shunt regulation kit...

Just a note - the stock Stereomour uses a different side of the 12AT7 on each channel so you can swap tubes to use the other side when the first one has used up its cathode. Waste not, want not!

That said, the shunt reg (and the DC filaments if they are needed) pulls the Stereomour up to the sonic level of the Kaiju but at half the power. This was important to me, since the Kaiju does not do 2A3s, unlike the Paramount it replaced.

[Natural Sound]

Just a note - the stock Stereomour uses a different side of the 12AT7 on each channel so you can swap tubes to use the other side when the first one has used up its cathode. Waste not, want not!

That said, the shunt reg (and the DC filaments if they are needed) pulls the Stereomour up to the sonic level of the Kaiju but at half the power. This was important to me, since the Kaiju does not do 2A3s, unlike the Paramount it replaced.

My only concern is using an expensive (Telefunken, Mullard etc) 12AT7 section as a shunt regulator. If I had my druthers I'd want one tube to drive the 2A3 like the original Stereomour and a second tube to handle shunt reg duties. That would allow for a premium tube to be used in the signal path and an inexpensive tube as a regulator. Tube rolling experiments in the past have shown that no real performance increase is gained by using a premium tube as a regulator. 

[Paul Joppa]

That should be easy to do if you have the experience. There is neither a manual nor instructions.

[Paul Birkeland]

My only concern is using an expensive (Telefunken, Mullard etc) 12AT7 section as a shunt regulator. If I had my druthers I'd want one tube to drive the 2A3 like the original Stereomour and a second tube to handle shunt reg duties. That would allow for a premium tube to be used in the signal path and an inexpensive tube as a regulator. Tube rolling experiments in the past have shown that no real performance increase is gained by using a premium tube as a regulator.

It's funny, we have never had any user (that I'm aware of) of the original Paramours, Stereomour, or Stereomour II actually wear out a premium 12AT7.  I wouldn't be surprised to see 30,000-100,000 hours of life of out of these driver tubes.

[Natural Sound]

It's funny, we have never had any user (that I'm aware of) of the original Paramours, Stereomour, or Stereomour II actually wear out a premium 12AT7.  I wouldn't be surprised to see 30,000-100,000 hours of life of out of these driver tubes.

I have on my Paramour II's with moderate to heavy use. I simply moved the wiring on each of the mono blocks to utilize the other section. I wish I thought of wiring my Paramour II's the way you setup the Stereomour II. I like the way you can just swap sockets. I'll wire mine that way once the second section goes out and I have to re-tube.

[amritdesai]

I think you'll be really happy with the shunt regulator upgrade. Installed mine last week and heard an immediate change in sound. I am elated with the JJ 2a3/shunt regulation combo! I honestly wasn't expecting such am improvement.

[Sugar Man]

I think you'll be really happy with the shunt regulator upgrade. Installed mine last week and heard an immediate change in sound. I am elated with the JJ 2a3/shunt regulation combo! I honestly wasn't expecting such am improvement.

I also installed mine and noticed an immediate change - haven't had a chance to critically listen yet - but sounds meatier even on my Spotify streaming from my iPhone to Airport Express.  Felt a bit of the stress of a brain surgeon while doing the detail work on the tube sockets trying to squeeze the soldering iron in without melting something....

What tubes are you running in your Eros and how do you like your Bitfrost?

[Paul Joppa]

I think you'll be really happy with the shunt regulator upgrade. Installed mine last week and heard an immediate change in sound. I am elated with the JJ 2a3/shunt regulation combo! I honestly wasn't expecting such am improvement.

The first time we tried to shunt-regulate the driver, I was not expecting much. A big change makes no sense from theory. I was so startled, I had to turn the amps over immediately to look for other changes. There weren't any. IMHO, theory gives you a good starting point, but listening remains the gold standard.

[amritdesai]

I also installed mine and noticed an immediate change - haven't had a chance to critically listen yet - but sounds meatier even on my Spotify streaming from my iPhone to Airport Express.  Felt a bit of the stress of a brain surgeon while doing the detail work on the tube sockets trying to squeeze the soldering iron in without melting something....

What tubes are you running in your Eros and how do you like your Bitfrost?

Paul and co have described the upgrade as an improvement in dynamic performance - I think this is spot on. I agree , the install was kind of stressful mostly because I had to some large capacitors to maneuver around. In the end, I had to get taller stand offs as the board would not fit. Working on those tube sockets was certainly a test in dexterity - it made me think about how good a dentist would be putting these kits together. No joke, it took me around 4 hours Also, the 12AT7 filaments are now much brighter - which I thought was pretty cool. I have all the upgrades bottlehead offers for the Stereomour II - I really think the shunt regulator made the most immediate improvement.

I don't want to highjack the thread but I absolutely love my Eros. I'm running EF86 telefunkens which I think really improved the treble energy in my system. I've noticed a bit more gain as well. Note, I'm running a 0.47uF Clarity CMR in the output stage. I felt this was an even more substantial upgrade in this regard. The Bifrost is great - a beautiful design and totally sufficient for my digital needs. To be honest these days I'm spending much more time listening to my analog system, especially for critical listening and dinner parties I have tidal and amarra which I use primarily to listen to new music and if I like it, I end up buying the LP.

Have fun dudes!

[adeep42]

Beautiful system. Isn't it amazing how good vinyl can sound. Are those speakers Zu's? By the way, I'm also running old Telefunken EF86s as well as an old Amperex 6922 in my Eros. I totally love it.