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DNA Stratus 2A3 amplifier - first impressions - Page 7

post #91 of 1866
Quote:
Originally Posted by dannie01 View Post

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.

Thinking about Donald's offer? I highly recommend it, when I had the Sonnet, it kick the WA6SE's ass left and right. The WA6SE did not last a week in my house.
post #92 of 1866
Quote:
Originally Posted by jc9394 View Post


Thinking about Donald's offer? I highly recommend it, when I had the Sonnet, it kick the WA6SE's ass left and right. The WA6SE did not last a week in my house.

 

Yes and thanks for that jc evil_smiley.gif, I am thinking about it seriously.


Edited by dannie01 - 6/18/12 at 5:50pm
post #93 of 1866
Quote:
Originally Posted by dannie01 View Post

 

Yes and thanks for that jc evil_smiley.gif, I am thinking about it seriously.

 

Oh, did I said that it with HD800?  It is a perfect match...  I only sold it to fund the WA22 purchase from someone.  biggrin.gif  Actually, I'm thinking on this too.  It takes the SE out of my DAC while beta22 takes the balanced out with loop out to WA22.  How perfect...beerchug.gif  Only if I have the funds...


Edited by jc9394 - 6/18/12 at 5:56pm
post #94 of 1866

We do have the rectifier already and 2A3 tubes are cheaper than 300B.

 

Donald, can we use GZ34/37, EML 274B, and USAF 596?

post #95 of 1866

Edit: Oops, forgot the quote.  I am referring to Donald enjoying the K1000s.

 

Probably safe to say he is.  So weird looking but so cool at the same time those K1000s are.  Knowing the Stratus has an output labeled specifically for them makes me want them.  I'm just that simple.  biggrin.gif

 

I would guess that a 45 tube Stratus would be great for high impedance, high efficiency phones.  A more three dimensional HD 800?  blink.gif

 

Alright, back to reality.


Edited by Eee Pee - 6/18/12 at 6:16pm
post #96 of 1866
Quote:
Originally Posted by Eee Pee View Post

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.

The Fi X originally was a 2A3-based amplifier. I believe Don will make a custom version optimized for the 45 - you need to ask him.

Quote:
Originally Posted by budx3385 View Post

 

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!

Yes, around 4 years ago I heard a friends K1000 and I was immediately hooked! I tried them with an Audio Note Kit One 300B amplifier and the combo sounded good. I love the 2A3 and have them driving my speakers, so I thought it could be really cool to develop a 2A3 amp with the proper output to drive the K1000.

Quote:
Originally Posted by Eee Pee View Post

Edit: Oops, forgot the quote.  I am referring to Donald enjoying the K1000s.

 

Probably safe to say he is.  So weird looking but so cool at the same time those K1000s are.  Knowing the Stratus has an output labeled specifically for them makes me want them.  I'm just that simple.  biggrin.gif

 

I would guess that a 45 tube Stratus would be great for high impedance, high efficiency phones.  A more three dimensional HD 800?  blink.gif

 

Alright, back to reality.

The 45 has higher plate impedance and lower power output. In order to load it properly you need an output transformer with twice the primary inductance as you would for the 2A3. Now assuming you use the same turns ratio on the primary:secondary windings, you'll have twice the output impedance. You can use a greater step down ratio to match the output impedance of the 2A3 but then you're giving up drive voltage. I wanted to keep the output impedance reasonably low to improve the drive on lower impedance headphones (and headphones which prefer a low impedance source) while providing sufficient drive voltage for lower efficiency headphones. The balance of these factors and fondness for the 2A3's sound are what lead to the Stratus' particular configuration.

post #97 of 1866
Quote:
Originally Posted by jc9394 View Post

 

Oh, did I said that it with HD800?  It is a perfect match...  I only sold it to fund the WA22 purchase from someone.  biggrin.gif  Actually, I'm thinking on this too.  It takes the SE out of my DAC while beta22 takes the balanced out with loop out to WA22.  How perfect...beerchug.gif  Only if I have the funds...

 

Your Beta22 is equip with this function? confused.gif

 

Quote:
Originally Posted by jc9394 View Post

We do have the rectifier already and 2A3 tubes are cheaper than 300B.

 

Donald, can we use GZ34/37, EML 274B, and USAF 596?

 

 

X 2 

post #98 of 1866
Quote:
Originally Posted by dannie01 View Post

Your Beta22 is equip with this function? confused.gif

Yes, I have the builder put in a loop out for me cause I'm too lazy to swap cables.
post #99 of 1866
Quote:
Originally Posted by jc9394 View Post

We do have the rectifier already and 2A3 tubes are cheaper than 300B.

 

Donald, can we use GZ34/37, EML 274B, and USAF 596?


I don't recommend the GZ34 & 37 because they are indirectly heated and I take the high voltage from the center tap on the filament winding. The Stratus needs directly heated rectifier tubes. 5R4GY can be used but will cause reduced plate voltage and current through the signal tubes. U52 can also be used. the EML 5U4G should be fine and I believe the EML 274B can work too because I use a current inrush limiting resistor immediately after the rectifier into the first capacitor. the USAF 596 has external anode pins and would require modification of the amp to accommodate, so I don't recommend it.

post #100 of 1866

.


Edited by preproman - 5/1/14 at 9:43am
post #101 of 1866
Quote:
Originally Posted by Donald North View Post


I don't recommend the GZ34 & 37 because they are indirectly heated and I take the high voltage from the center tap on the filament winding. The Stratus needs directly heated rectifier tubes. 5R4GY can be used but will cause reduced plate voltage and current through the signal tubes. U52 can also be used. the EML 5U4G should be fine and I believe the EML 274B can work too because I use a current inrush limiting resistor immediately after the rectifier into the first capacitor. the USAF 596 has external anode pins and would require modification of the amp to accommodate, so I don't recommend it.

 

What if I have an external adapter for it?  

 

93213a2c.jpg

post #102 of 1866

I want to know, too.

 

BTW, nice pic, jc. Is it taken by the D8000. biggrin.gif


Edited by dannie01 - 6/19/12 at 7:24am
post #103 of 1866
Quote:
Originally Posted by dannie01 View Post

I want to know, too.

 

BTW, nice pic, jc. Is it taken by the D8000. biggrin.gif

 

You mean D800?  I wish, still in waiting list... 

post #104 of 1866
Quote:
Originally Posted by preproman View Post

Revered 

Intentional?

post #105 of 1866
Quote:

Originally Posted by jc9394 View Post

 

You mean D800?  I wish, still in waiting list... 

 

Hehe, sorry for typo.

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