[econparanoia]

I'm on the market for a headphone amp for my HD800 (using the Invicta DAC.) And I'm having a hard time choosing between the DNA Stratus and the EC Super 7 (S7) . Let's assume that they both use their stock tubes.
 
1) Which one has a larger soundstage?
2) Which one has a deeper soundstage?
3) Which one has better instrument separation and more precise imaging. 
4) Which one sounds warmer? Which one sounds smoother?
4) Which one is more detailed and transparent?
5) Which one has better bass? (I am under the impression that S7 has tigher bass while Stratus' bass might be a bit muddy. Am I correct?)
 
Look forward to thoughts/opinions! 

 

[ValentinHogea]

I'm actually in the same spot as you, however I've also taken the remaining two EC amps in consideration...
 
 
[size=1.45em]Super 7[/size]
Pros

1. Price 1650 USD
2. The price of tubes (a "tube rolling pack" seems to go for about 300 USD total, and that gives a lot of options...)
3. "Infinite" possibilities to customize the sound to different phones
4. Can drive efficient speakers

Neutral

1.  

Cons

1. Well it ain't exactly the prettiest of the bunch, no pun intended

 
 
[size=1.45em]EC 2A3[/size]
Pros

1. Separate power supply

Neutral

1.  

Cons

1. Expensive 2800
2. Expensive tubes (2A3/5AR4/6SL7)

 
Question: Can it handle 300B also?


[size=1.45em]EC Zana Deux SE[/size]
Pros

1. I've had and loved an OTL-amp previously
2. Cheap rectifier tubes
3. Cheap output tubes

Neutral

1. Not much customization due to unusual tubes, which might also be good. Less tuberolling-OCD.
2. Midpriced

Cons

1. Expensive driver tube (6SL7)
2. No real possibility to tube roll

 
 
[size=1.45em]DNA Stratus[/size]
Pros

1. On paper it has most output... Unclear if so in real life. 1,8 W into 50 Ohms.

Neutral

1.  

Cons

1. Extremely expensive tubes (2A3/6992/5U4G)
2. It's smurf-colored

 

[BournePerfect]

FYI most user impressions of the ZDSE say that only the driver tube rolling affects sonic changes noticeably, not the 'cheap' rectifier or power tubes. Haven't tried replacing those myself-but the driver most certainly can change the sound.
 
-Daniel

 

[SleepyOne]

For EC2A3 rectifier tube is cheap. I get great result with cheap Sevtek GZ34 and result seems better than expensive Philip Holland double-D getter tube (amount the best). For EC2A3 rectifier rolling does affect sound.
As for power tube, the option is either 2A3 or 45. It cannot do 300B. I think you can get decent reasonablely priced Chinese 2A3 like psvane etc. Apart from 6SL7, you could go 6C8G (need adapter) with great result.

 

[third_eye]

For me it was an easy choice between the S7 and Stratus. But, there is a pretty big price difference and I think the S7 is a great amp for the price. I've swapped all of the tubes in my Stratus for about $400, the most expensive and the ones that make the biggest difference are the 2A3's. Two of the recommended ones are the Sophia Princess ($325 a pair), or EML Mesh or Solid ($550 a pair). They do make a big difference over the the stock tubes which already sound very good.

 

[econparanoia]

Thank you for your opinions, guys! The Super 7 seems to be of better value to me. Yet, I do like the look of the Stratus better. And I am under the impression that the Stratus belongs to a higher class.
 
Third_eye, did you settle down with the Sophia Princess and spent about $75 on the rest of the tubes? If so, would you please let me know your choice of the rest of the tubes? Also, any more impression on the Stratus' bass? Member purrin once suggested that the bass of the Stratus sounded a bit muddy and less tight in comparison with EC amps. What do you think? And did tube rolling improve the bass quality for you?

 

[BournePerfect]

Supposedly Craig is redesigning the next batch of S7s to be more in line with the ZDSE/2A3 chassis-so the looks will look...super...from here on hopefully. Food for thought.
 
-Daniel

 

[third_eye]

Quote:

Thank you for your opinions, guys! The Super 7 seems to be of better value to me. Yet, I do like the look of the Stratus better. And I am under the impression that the Stratus belongs to a higher class.
 
Third_eye, did you settle down with the Sophia Princess and spent about $75 on the rest of the tubes? If so, would you please let me know your choice of the rest of the tubes? Also, any more impression on the Stratus' bass? Member purrin once suggested that the bass of the Stratus sounded a bit muddy and less tight in comparison with EC amps. What do you think? And did tube rolling improve the bass quality for you?

I'm settled with the Sophia's at $325, a NOS RCA 6BQ7A input tube, and a NOS RCA 5U4G at about $35 a piece. My 6BQ7A is cryo'd so it was a little more, usually those input tubes are $10-15 at most. I would not classify the bass of the stock Stratus as "muddy" per se, but rather a little more tubey or loose if you will. Does that mean muddy? In any case, the tube rolling greatly improves the bass quality and the resolution. I feel like I'm getting all of the resolution of the HD800 without the treble peaks and with great bass. It's exactly the sound I was looking for.

 

[Donald North]

The Stratus does produce 1.8W into 50 ohm load – this is what I measured using my Audio Precision System 2. I am able to achieve this in the Stratus by using custom output transformers with reduced step-down turns ratio in order to produce greater output voltage than a typical 2A3 speaker amplifier.
 
Also, the Stratus does not use the 6922 for the input tube. It uses the 6N1P which has different plate impedance and transconductance electrical parameters and should not be interchanged.
 
The stock tube set can be replaced for approximately $120 + shipping through online dealers.
Quote:

[size=1.45em]DNA Stratus[/size]
Pros

1. On paper it has most output... Unclear if so in real life. 1,8 W into 50 Ohms.

Neutral

1.  

Cons

1. Extremely expensive tubes (2A3/6992/5U4G)
2. It's smurf-colored

 

[ValentinHogea]

Quote:

The Stratus does produce 1.8W into 50 ohm load – this is what I measured using my Audio Precision System 2. I am able to achieve this in the Stratus by using custom output transformers with reduced step-down turns ratio in order to produce greater output voltage than a typical 2A3 speaker amplifier.
 
Also, the Stratus does not use the 6922 for the input tube. It uses the 6N1P which has different plate impedance and transconductance electrical parameters and should not be interchanged.
 
The stock tube set can be replaced for approximately $120 + shipping through online dealers.

Hi Donald!
 
Thanks for your input!
 
What I meant to say was that it does use tubes that can get very expensive around 230 USD for a matched pair of Sophia Electric // JJ // TJ Full mesh not to even get into the EML's at 700 USD. Thanks for clarifying regarding the 6N1P vs 6992. I wasn't aware of that. My current tube knowledge is centered around 6AS7 / 6SJ7 / 5964-type tubes. So this is a new field... The same thing goes for 6SL7's. Albeit a bit cheaper than 6SN7's, it's not like picking up a pair of RCA Reds 5693's matched NOS for 40 USD... It's most important to me that this isn't interpreted as critique. It very natural that top-of-the-line amps use the best designed-for-audio tubes. And therefore, unless one stays strictly Russian/Chinese with the tubes, the costs start rising.
 
This is however, just as real for the EC 2A3-amp. And well.. Any amp in general that uses bigger output tubes á la 2A3 / 300B with the exception of the ZDSE that uses most uncommon tubes, and therefore is limited to the stock ones. Which as I wrote earlier can be both a good and bad thing.
 
A question though... How many hours are the tubes in the Stratus expected to last. Normal operation. Not any compulsive on-off 20 times a day. Regular listening.
 
/V

 

[SleepyOne]

I guess that's the price for going into triods territories (45, 2A3 or 300B). Still if you are ok with not top of line power tubes, price isn't that bad, I mean something like psvane or shuguang 2A3B/C isn't that expensive and can have for < £60. Rectifier & driver tubes only cost £20-50 (depending on your choice of driver). Thus total cost will be around £100. If you want better quality power tube, yup, cost of rolling can be expensive for sure, esp. if you go for 300B....

 

[Frihed89]

I have not heard the Super-7 and did not know much about it until a head-fi colleague and fellow resident of Copenhagen set me straight on its topology.  (For example, I thought it was an OTL amp!).
 
So, what I have to say about the Super-7 is sheer guess-work.
 
But I do own the Stratus.  I do have the AVVT meshplates, plus some older double plates and have tried other 2A3 tubes, as well.  They all sounded differently.  The biggest gap was between the RCA double plates (warm all over) and the AVVTs (neutral and balanced).  The differences match my own mood swings when I listen to music.  I also bought a large number of different types of 6BH7As.  There are differences between them, but they are all warner then the stock 6N1P.  I also have one early 70s 6N1P and some others from later dates.  There is not that much difference between them and i am not sure that I am not imagining the differences.  The stock tube is as good as any.  The 6N1P has better detail and is more neutral than the 6BH7s and certainly a cleaner top end.  It is also a bit grainy.  On some days i think about temporarily subbing my Telefunken and Siemens E188CCs, but haven't done it due to electrical differences + Donald's warning.  The Rectifier matters.  My Raytheon 5U4GB outperform the stock Russian tubes on the bottom and top ends, particularly the bottom.  Nevertheless, the stock Russian 5U4G is no slouch.  I use it a lot because my supply of Raytheons is not that large.
 
What i like about the idea of the Super 7 is the 6SN7 driver and output tubes.  I would think that the brand/type/vintage of the 6SN7 driver (or electrical equivalent) would have a large impact on what one hears.  I have a lot of vintage (i hesitate to call them NOS) 6SN7GT "type" tubes and found, for example, that driver selection made a large difference in what I heard coming out of my SinglePower MPX3 Slam SE.  But so did the output tubes.  I don't know if this will be true of the Super7.  What I do know is that all of the GT-types (including the 6SN7W and WGT) are getting quite expensive, while the term NOS is being heavily abused.  There's a lot of uncertainty, here.  But with claimed NOS pairs of, say, Raytheon 6SN7GT/VT-231 T plates going for over $250/pair compared to $50 for a pair of used tubes (usually flat plates), there's a lot of room for randomness to set in.  In my MPX3, the sound differed dramatically depending on the tubes I used and where I used them.  The same is true for the effect of the 6SN7GT driver on my preamp and a Class A KT-88 triode wired PP amp I have where both the driver and phase splitters are 6SN7GTs (although the KT88/6550 tends to dominate).
 
With the Stratus, the differences are just not as great as I experienced in the MPX3.  Thus, there us less uncertainty about what you will hear and what it will cost to tube to this amp.  Yes, a Shuguang 2A3 tube will not sound as good as an AVVT or an EML. But the AVVT is unobtainable and the EMLs are in the $500 range (i have their 45 solid plate, not their 2A3).  Go over to the Stratus thread.  Despite minor disagreements, pretty much everyone describes the same sound.
 
Good luck.