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DNA Stratus 2A3 amplifier - first impressions - Page 21

post #301 of 2061

#11 is here!!! And it sounds GREAT!!! Sophia Princess 2A3's and cryo'd NOS 6bq7a are standing by but I'm going to let this burn in for a while before I start tinkering. Donald personally delivered the amp and helped set it up, big THANK YOU! Will post more impressions and pics soon.

post #302 of 2061
Thread Starter 
Quote:
Originally Posted by third_eye View Post

#11 is here!!! And it sounds GREAT!!! Sophia Princess 2A3's and cryo'd NOS 6bq7a are standing by but I'm going to let this burn in for a while before I start tinkering. Donald personally delivered the amp and helped set it up, big THANK YOU! Will post more impressions and pics soon.

You lucky guy !!!   Congrats !!!

post #303 of 2061

Perhaps I have missed it when I read through this thread earlier, but I would appreciate it if someone commented on their impressions of how the HD800 compares to LCD-2/3 and/or HE-6 on this amp. Anyone have the Senns and the planars, and listened to both? 

post #304 of 2061

There may be some misunderstanding about my design choice on the 2A3 DC heater supplies used in the Stratus, and I would like to clarify here. They are an unregulated design using capacitor-resistor-capacitor filtering with hum nulling pots. Whereas some commonly used regulated DC supplies are in the signal path and can negatively affect the sound (discussed at length elsewhere on the internet), I intentionally chose to use an unregulated supply with user-adjustable trim pots to fine tune for the symmetry of each tube's filament and minimize the signal current flowing through the DC supply for better sonics, in my opinion.

post #305 of 2061

Donald I have recently been adjusting the trim pots to better understand their effect on the sound.  It is oddly akin to a balance pot just on a VERY subtle level.  When it hits the sweet spot, you know it - like achieving that special holographic 3D quality of the perfect sitting position.  Can you explain more how this works?  Thanks

post #306 of 2061

The potentiometer balances the residual ripple of the DC supply across the filaments and nulls it out. It also helps balance the signal current through the filament. While not commonly employed in commercial amplifiers, the concept of DC supply with balancing pot is frequently discussed and recommended in tube enthusiast forums and informational sites.

post #307 of 2061

Are there any more Stratus being made?  If so Can I pay for a customized (black) enclosure?

post #308 of 2061

To the owners of a Stratus amplifier, do you notice audible humming using more sensitive headphones?

Not talking about IEMs but rather 62 ohms AKG's. Would be quite the dealbreaker if there would be humming on a $2.5K amplifier.


Edited by Baten - 11/29/12 at 6:56am
post #309 of 2061
Quote:
Originally Posted by Baten View Post

To the owners of a Stratus amplifier, do you notice audible humming using more sensitive headphones?

Not talking about IEMs but rather 62 ohms AKG's. Would be quite the dealbreaker if there would be humming on a $2.5K amplifier.

Mine is silent with all my headphones.

post #310 of 2061
Quote:
Originally Posted by santacore View Post

Mine is silent with all my headphones.

 

Great, thanks :)

post #311 of 2061

I build the Stratus to order. All are made with the high gloss blue chassis.

Quote:
Originally Posted by preproman View Post

Are there any more Stratus being made?  If so Can I pay for a customized (black) enclosure?

post #312 of 2061

No hum on mine unless turned to 10 - and even that you can almost balance out.  This is different from tube microphonics, of course, which you control with choice of glass.  *Many* tubes off untrusted sites are noisy like a radiator...

 

 

Quote:
The potentiometer balances the residual ripple of the DC supply across the filaments and nulls it out. It also helps balance the signal current through the filament. While not commonly employed in commercial amplifiers, the concept of DC supply with balancing pot is frequently discussed and recommended in tube enthusiast forums and informational sites.

 

Thanks Donald - another layer of fun!!!

post #313 of 2061
Quote:
Originally Posted by fejnomit View Post

No hum on mine unless turned to 10 - and even that you can almost balance out.  This is different from tube microphonics, of course, which you control with choice of glass.  *Many* tubes off untrusted sites are noisy like a radiator...

 

Thanks. I see you have both a WA6SE and the Stratus, any chance you can give a quick and dirty comparison?

I'm new to the tube scene and am very much considering Donald's amps, one gripe/fear is that I don't like my sound too laid-back (I sold my HD650 because of this),

I like the sound a little bright as long as it doesn't hurt / isn't plain fatiguing. What I'd love in a tube amp is 3D-sound presentation, realism, transparent soundstaging.

So basically I want a more realistic-lifelike sound but not ridiculously smoothed out, can this be achieved through tubes? Advice much appreciated.


Edited by Baten - 11/29/12 at 1:33pm
post #314 of 2061

The residual ripple hum, which is nulled with the potentiometer, should be independent of volume control setting. When you turn the volume to max, perhaps you're hearing noise from your source or an pickup from an unshielded interconnect?

Quote:
Originally Posted by fejnomit View Post

No hum on mine unless turned to 10 - and even that you can almost balance out.


Edited by Donald North - 11/29/12 at 3:59pm
post #315 of 2061
Quote:
Originally Posted by Baten View Post

 

Thanks. I see you have both a WA6SE and the Stratus, any chance you can give a quick and dirty comparison?

I'm new to the tube scene and am very much considering Donald's amps, one gripe/fear is that I don't like my sound too laid-back (I sold my HD650 because of this),

I like the sound a little bright as long as it doesn't hurt / isn't plain fatiguing. What I'd love in a tube amp is 3D-sound presentation, realism, transparent soundstaging.

So basically I want a more realistic-lifelike sound but not ridiculously smoothed out, can this be achieved through tubes? Advice much appreciated.

that is exactly my experience with Donald's amps!

I have also read that Woo is more on the tubey side, but i have not heard them.

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