[hpeter]

So far i heard only sovteks and JJ, a tiny bit more i like the JJ. Less fatigue or something with jj, but sound is good on both.
Funny story that some people say the jj is just 300b with 2,5~ filament.. When i roll them, bias is almost same

 

[auricgoldfinger]

I have a stupid question:  can the Stratus drive the SR-007 and SR-009 on its own or is a separate amp still recommended?

 

[bigfatpaulie]

  I have a stupid question:  can the Stratus drive the SR-007 and SR-009 on its own or is a separate amp still recommended?

 
No.  And no.  
 
No.
 
The SR's are electrostatic headphones and even with something like Woo WEE you really couldn't make this work.

 

[auricgoldfinger]

Thanks!

 

[stuart1927]

I was doing a comparison between the DNA stratus and my Cavali liquid carbon last night.
 
What surprized me was how good the LC is. The differences are actually quite subtle. The Stratus wins out in terms of absolute balance and soundatage, but the little LC is a very good amp.
 
I actually think the LC has more grunt than the Stratus. That's my only minor disappointment with the Stratus, for such a large unit, the output is not spectacular. It can drive all my cans well enough, but it needs to be turned up pretty high to drive some of them. I would have liked a bit more headroom.
 
Bt contrast, the little Cavali LC has bags of headroom and I never have it turned up beyond 10 o'clock.
 
Has anyone else found this to be the case?
 
 
sbb

 

[eserafinojr]

Apples and Oranges. The Stratus is a Class A SET amp, the Carbon a modern Solid State with lots of power.
 
Single Ended Triode design amplifiers like the Stratus are lower power output amps truly designed for extremely efficient speakers and horn speakers. For raw power output for inefficient speakers and harder to drive headphones an OTL/OCL or Push Pull Tube amps are ideal.
 
The most powerful SETs put out 6-8W, most are in the 1.8 to 3W range. But that should be more than enough for even relatively harder drive headphones like Orthos and High Impedance Dynamic cans.
 
Do you use a Pre-Amp with your Stratus? @stuart1927
 
If not it would certainly help with gain if you did or if your DAC has variable outputs with volume control.
 
What makes SETs so nice is the wonderfully nuanced, natural and analog sound of a directly heated triode like the 2A3 and 45.
 
BTW I don't own a Stratus (Would love to one day) but am very familiar with SET amps.
 
Perhaps and I'm just taking a guess here.... if the Stratus is a little light in the power dept. maybe DNA might have been better off with 2 driver tubes instead of 1 or opting for full size octals like the 6J5/6N7/6SN7/6SL7/6SJ7 types.

 

[stuart1927]

My DAC does have a preamp so maybe I will experiment a little. I'm not unhappy with the stratus sound....Just surprised that the ultimate output isn't "larger" for such a "big" amp.

 

[auricgoldfinger]

I have never felt a need for more power with my Stratus and HE1000.  I keep the volume knob at 5 and make further adjustments using the volume control on my DAC.  Depending on the recording, my DAC is set anywhere from 35 to 60 (on a scale of 100).

 

[parbaked]

  I actually think the LC has more grunt than the Stratus. That's my only minor disappointment with the Stratus, for such a large unit, the output is not spectacular. It can drive all my cans well enough, but it needs to be turned up pretty high to drive some of them. I would have liked a bit more headroom.
 
Bt contrast, the little Cavali LC has bags of headroom and I never have it turned up beyond 10 o'clock.

That can also be due to the volume pot. The Stratus uses a nice TKD pot which have a very smooth taper with a wide range of use. This is good for more powerful amps.
 
IIRC the LC uses a small ALPS pot designed for portable amps. These can have a more aggressive taper to better suit lower powered amps. 
 
If the volume pots are different you might be comparing the potentiometer's taper and not the amp's power.
 
The best way to compare is to turn the volume pots full on both amps and use the volume on your DAC to adjust volume.
See how much you need to turn up the DAC to get comparable volume from each amp.
This will remove the amp's volume pots from the chain and you will be comparing the amps and not the volume potentiometers.

 

[Donald North]

Perhaps and I'm just taking a guess here.... if the Stratus is a little light in the power dept. maybe DNA might have been better off with 2 driver tubes instead of 1 or opting for full size octals like the 6J5/6N7/6SN7/6SL7/6SJ7 types.

The Stratus (and Stellaris) use the 6N1P for driver duties and has more than enough gain (mu of 35) to drive the 2A3 to full power. The 6J5 and 6SN7, for example only have a mu of 20. The 6SL7 has too much gain, in my opinion, combined with a high plate impedance with associated complications.

I like your suggestion for him to max the volume control on both amps and use the variable out from his DAC and compare.

 

[eserafinojr]

Hi Donald,

Thanks for chiming in.

Always been an admirer of your work!

Make sense, the The 6N1 is a medium Mu Triode.

Yes the 6SL7 is not for every application. Truthfully they are better suited for OTLs and P-P amps.

Another medium Mu triode I'm a fan of is the 6N7, which like the 6N1 has an amplification factor of 35 but half of the 6N1s Gm.

Do you do custom order specifications?

Would I be able to order a Stratus with a 6N7/G Octal Driver or Twin 6J5/6C5?

Just curious about that.

I have lots of those octal types. I like to use amps that i have a large stock of the tubes the amp uses. Also does the Stratus accept the 6922 in place of that 6N1 socket?

 

[froger]

I was doing a comparison between the DNA stratus and my Cavali liquid carbon last night.

What surprized me was how good the LC is. The differences are actually quite subtle. The Stratus wins out in terms of absolute balance and soundatage, but the little LC is a very good amp.

I actually think the LC has more grunt than the Stratus. That's my only minor disappointment with the Stratus, for such a large unit, the output is not spectacular. It can drive all my cans well enough, but it needs to be turned up pretty high to drive some of them. I would have liked a bit more headroom.

Bt contrast, the little Cavali LC has bags of headroom and I never have it turned up beyond 10 o'clock.

Has anyone else found this to be the case?


sbb

I am on the other end of the spectrum. I found Stratus's gain too much for the efficient Focal Utopia. I am using around 1 and 2. Nowadays, I use the the volume control of my DAC for small volume control instead. I do listen at quite low volume though.

 

[Donald North]

Hi Donald,

Thanks for chiming in.

Always been an admirer of your work!

Make sense, the The 6N1 is a medium Mu Triode.

Yes the 6SL7 is not for every application. Truthfully they are better suited for OTLs and P-P amps.

Another medium Mu triode I'm a fan of is the 6N7, which like the 6N1 has an amplification factor of 35 but half of the 6N1s Gm.

Do you do custom order specifications?

Would I be able to order a Stratus with a 6N7/G Octal Driver or Twin 6J5/6C5?

Just curious about that.

I have lots of those octal types. I like to use amps that i have a large stock of the tubes the amp uses. Also does the Stratus accept the 6922 in place of that 6N1 socket?

The Stratus chassis have all been made to fit a 9-pin tube socket. More importantly, I looked up the specs and plate curves for the 6N7. While it has a mu of 35 the plate impedance is 22k, which around 3 times higher than the 6N1P, and makes it much more difficult load with a high resistive load while attaining an optimum bias condition with a 300V supply. 2A3s run at a lower voltage than 300Bs, for example, so there is less voltage available with which to work for the driver tube.

When I started development of the Stratus I tried the 6922 first but it didn't sound as good as the 6N1P. Of course while comparing I changed the bias circuit for each tube because they have different electrical parameters, and the 6N1P won out.

 

[stuart1927]

The Stratus (and Stellaris) use the 6N1P for driver duties and has more than enough gain (mu of 35) to drive the 2A3 to full power. The 6J5 and 6SN7, for example only have a mu of 20. The 6SL7 has too much gain, in my opinion, combined with a high plate impedance with associated complications.

I like your suggestion for him to max the volume control on both amps and use the variable out from his DAC and compare.

Interesting!...So I have a Musical Paradise dac, the MP-D2, which has a pre-out, and I paired up to one of the inputs on the Stratus. I maxed out the volume on the stratus and controlled volume from the Musical Paradise dac. Sound was pretty good....not done enough listening to see what sounds better.
 
I don't know much about the theory of electronics, but am curious what is actually happening when I connect up in this way. The dac is functioning as a pre-amplifier, but the Stratus is essentially an integrated amp, so what is it actually doing.....is it pre-amping a signal from the pre-amp, or is it  just acting as a power amp? 
 
Apologies if this seems like a lame question, but I've always struggled to understand how this works!
 
sbb

 

[parbaked]

Originally Posted by stuart1927 /img/forum/go_quote.gif
 
The dac is functioning as a pre-amplifier, but the Stratus is essentially an integrated amp, so what is it actually doing.....is it pre-amping a signal from the pre-amp, or is it  just acting as a power amp? 

Stratus is a power amp with a volume potentiometer. It has no "preamp" as such. You can bypass the potentiometer by turning it up all the way, and the Stratus will function as a power amp.
How your DAC controls volume is another story...
 
The output of DACs and most modern sources is high enough that the Status does not need a preamplifier to further amplify the signal to achieve full output.