DNA Stratus 2A3 amplifier - first impressions

[budx3385]

The Sophia Electric Princess 2A3s have burned in for 70-90 hrs now, and they seem to have stabilized. I like their SQ, excellent presence, a bit underpowered in the deep bass, but it's all there. They do not sound as slow and rounded off on the fast transients as they did after 0-40 hrs, and they definitely sound clearer with more resolution now than the NOS RCAs. I would choose these over the NOS tubes that are here.
 
Then I put the EML meshplates back in. They have been sitting, having burned in for >160hrs. Their SQ is really quite similar to the SQ of the Princess 2A3s -- makes me think that the main sources of the SQ now are the Bricasti M1 DAC, the i/c, and the Stratus. I really enjoy the presence, the feeling of "you are there". And now I really enjoy the deeper micro-detail, the control, the sense of solidity, and the outstanding clarity of these EMLs. The bass is outstanding, which gives the sense of presence a real visceral quality, easy to drift into emotionally and just enjoy the music.
 
So, at present, my order of preference is EML mesh, Sophia Princess, NOS RCA blackplates, and then stock Shuguang.
 
I should stop now and enjoy the music, right? Yup. Well, I ordered the new Shuguang Treasure Natural Sound 2A3C-Ts that I found on ebay yesterday, and I plan to follow up on Frihed89's suggestion and order the EML solidplates tomorrow. Madness? Obsession? I am absolutely convinced that the Stratus is a top-quality amplifier, and I want to have the best possible tubes in it. I'll be happy to share my impressions, as I hope all of the new owners will. I heard that the next Stratus was just shipped
.

 

[bdh]

Quote:

I should stop now and enjoy the music, right? Yup. Well, I ordered the new Shuguang Treasure Natural Sound 2A3C-Ts that I found on ebay yesterday, and I plan to follow up on Frihed89's suggestion and order the EML solidplates tomorrow. Madness? Obsession? I am absolutely convinced that the Stratus is a top-quality amplifier, and I want to have the best possible tubes in it.

 

I feel the same way after every new tube amp I've gotten.
As far as I know, I still have the only 45\2a3 Balancing Act.
I also have solid and mesh-plate EMLs.  They are so much better than any NOS I've heard.
As far as preferences between solid and mesh, it is very dependent on the driver and source I am using.
But I always prefer the 45's over the 2a3.  The 2a3 has a somewhat wider soundstage, but the 45's are more three-dimensional, have more presense, and are more musical and engaging to me.
I've stopped for quite a while now and am enjoying the music immensely.
 
Okay, there is still a small temptation to try the EML Globe 45's. 

 

[madbull]

I got my Stratus today. No photo can do justice to the beauty of this amplifier... And oh my, it's HUGE! Unfortunately I can't even turn it on because voltage is not compatible (I'm on vacation, away from home).

Did I say it's beautiful?

I will try to post some photos in a couple of days...

Thanks to Donald for providing us such a wonderful equipment.

 

[dannie01]

Thanks for the review, budx.
 
I have a WA5LE for HD800, LCD-3 and DX-1000 and have question here, does anyone compare the WA5LE and Stratus, they are both Single Ended Triode Class A amplifier with output transformer design and similar power output. I'm interested with Stratus because of this wonderful review but the design of Stratus is similar to WA5LE (I might be wrong here because I am not expert in this field, sorry about that), of course both 2 amps are top notch. Read from this thread it sounds wonderfully with HD800 but how does it sound with LCD-3? How perform different between these two great amp?
 
Thanks in advance.

 

[Anaxilus]

I'd take the Stratus over the WA5LE.  The sound of Woo amps haven't retained their value for me like others brands have.  I'd consider Woo maybe top 10 but not top 5 for my criteria.

 

[Donald North]

The WA5LE uses 300B output tubes whereas the Stratus uses 2A3. These two tubes have different sound characteristics. From my experience I would say the 300B sounds like it is putting on a good show, trying to impress you, whereas the 2A3 is more direct and matter of fact. Additionally the two amps use different input tubes, output transformers, and passive components, so while they are both single ended triode class A amplfiers with output transformers, they will sound different.
Quote:

 
I have a WA5LE for HD800, LCD-3 and DX-1000 and have question here, does anyone compare the WA5LE and Stratus, they are both Single Ended Triode Class A amplifier with output transformer design and similar power output. I'm interested with Stratus because of this wonderful review but the design of Stratus is similar to WA5LE (I might be wrong here because I am expert in this field, sorry about that),

 

[budx3385]

Quote:

 

I feel the same way after every new tube amp I've gotten.
As far as I know, I still have the only 45\2a3 Balancing Act.
I also have solid and mesh-plate EMLs.  They are so much better than any NOS I've heard.
As far as preferences between solid and mesh, it is very dependent on the driver and source I am using.
But I always prefer the 45's over the 2a3.  The 2a3 has a somewhat wider soundstage, but the 45's are more three-dimensional, have more presense, and are more musical and engaging to me.
I've stopped for quite a while now and am enjoying the music immensely.
 
Okay, there is still a small temptation to try the EML Globe 45's. 

 
Gee Whiz, you got my ears up. I've never heard the 45 described that way - always thought it had way less character than a 300B or a 2A3.
 
Would the 45 work in the Stratus? The specs look similar, but maybe not close enough -- 2.5V filament, 300V plate, however, transconductance of 2.2mA/V instead of 5.5, and plate dissipation of 8-12 watts instead of 15-30 watts. 

 

[budx3385]

Quote:

I got my Stratus today. No photo can do justice to the beauty of this amplifier... And oh my, it's HUGE! Unfortunately I can't even turn it on because voltage is not compatible (I'm on vacation, away from home).
Did I say it's beautiful?

I will try to post some photos in a couple of days...
Thanks to Donald for providing us such a wonderful equipment.

 
WAY TO GO, madbull!!! Looking forward to hearing about what you hear as well as what you see!

 

[Donald North]

The 45 is a very good sounding tube and I prefer it to the 300B. In my experience the 2A3 sounds closer to the 45 than 300B. Electrically the 45 has twice the plate impedance of the 2A3 thereby requiring different output transformers with twice the primary inductance. It also requires different cathode resistors to get the proper plate current for self biasing. Filament voltage is the same but current draw is different. An amp that's designed and optimized for the 2A3 isn't optimum for the 45 and vice versa. I don't recommend the 45 in the Stratus.
Quote:

 
Would the 45 work in the Stratus? The specs look similar, but maybe not close enough -- 2.5V filament, 300V plate, however, transconductance of 2.2mA/V instead of 5.5, and plate dissipation of 8-12 watts instead of 15-30 watts. 

 

[Eee Pee]

Quote:

 An amp that's designed and optimized for the 2A3 isn't optimum for the 45 and vice versa. I don't recommend the 45 in the Stratus.

 
You've forecasted your future.  

 

[bdh]

Quote:

 
Gee Whiz, you got my ears up. I've never heard the 45 described that way - always thought it had way less character than a 300B or a 2A3.
 
Would the 45 work in the Stratus? The specs look similar, but maybe not close enough -- 2.5V filament, 300V plate, however, transconductance of 2.2mA/V instead of 5.5, and plate dissipation of 8-12 watts instead of 15-30 watts. 

 
I've always heard it has more character and more realism than 300B and 2A3, and does so in my experience, but it is more limited due to having half the output power of the already miniscule 2A3, which can be a limitation for speaker setups.  And as Donald says, the plate impedence is higher on the 45, so the bass can be a bit stronger with the 2A3.  Not much in my opinion, and I also have no issue compensating digitally.
 
The 2A3 still sounds great and has a very big sound.  I would love to compare the BA 2A3 with the DNA 2A3.  I am using an ECC32 for the input.  I've never heard an amp using the tube the DNA uses as an input.
 
Everyone definately has different preferences.

 

[dannie01]

Quote:

The WA5LE uses 300B output tubes whereas the Stratus uses 2A3. These two tubes have different sound characteristics. From my experience I would say the 300B sounds like it is putting on a good show, trying to impress you, whereas the 2A3 is more direct and matter of fact. Additionally the two amps use different input tubes, output transformers, and passive components, so while they are both single ended triode class A amplfiers with output transformers, they will sound different.

 
Thanks Donald for the explanation.

 

[Eee Pee]

Quote:

An amp that's designed and optimized for the 2A3 isn't optimum for the 45 and vice versa. I don't recommend the 45 in the Stratus.

I was thinking about this sentence today because I recall an amp from Don Garber's of Fi to be able to use both tubes if you change the rectifier.   The Fi X.  And I'm guessing it isn't optimized for either tube?  That's too bad.  It does get nice reviews though.

 

[budx3385]

^^
 
Quote:

 
You've forecasted your future.  

 
and I've been thinking about your comment here, EeePee. I finally pulled the K1000 out of my closet, and it sounds amazingly realistic driven by the Stratus. (Now I really need to fix its extension cable, cuz its 6 ft original does not reach my listening chair.) If I remember correctly, driving the K1000 was one of Donald's design aims for the Stratus. I'm guessing he is enjoying that combo every day now!

 

[santacore]

Yes, Donald definitely designed this amp with the K1000's in mind, along with the popular planars.