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DNA Stratus 2A3 amplifier - first impressions - Page 36

post #526 of 2334

Personally I wouldn't worry about the driver tubes, like you said.  They're cheap anyway...

 

That first 5U4G sounds great - 56 and 56 is a perfectly balanced tube.  The second sounds like it's probably good too.

 

I hope Donald will chime in about the dangers to the amp. 

 

Personally I don't have a tester - I just try what I buy and hope for the best...  WITHOUT HEADPHONES ON WHEN I FIRE UP THE AMP.  Like I said, I learned that one the hard way...

post #527 of 2334

Answering several recent questions:

1. I tried a couple 5U4GB in my Stratus and they work fine. It runs the tubes a little higher plate dissipation but still within the published limits.

2. I haven't tied yet the 274B rectifier.

3. The ST in 5U4G ST refers to the glass envelope shape. This is the classic 5U4G shape.

4. A source for tested 6N1P-EB(EV) is Tube Depot

5. A recent Stratus customer ordered a set of the Psvane 2A3-T and reports they're a nice improvement over the stock Shuguang 2A3B.

6. When buying tubes through the internet, try to find sellers who use more sophisticated tube testers and publish both Ip (plate current) and Gm (transconductance) for both sections of the dual triode. This is better than a figure of merit as found on many testers.

7. The Stratus produces 9.5Vrms with 8 ohm output impedance into a 50 ohm load. Reducing the step-down turns ratio to increase output voltage also increases the output impedance based on the turns ratio squared. It's not clear to me that this will provide improved results with the HE-6. At the recent CHANGfest meet I tried the HE-6 with the Stratus and found the combo played plenty loud for me with headroom to spare. YMMV.


Edited by Donald North - 3/6/13 at 10:47pm
post #528 of 2334
Quote:
Originally Posted by Donald North View Post

Answering several recent questions:

1. I tried a couple 5U4GB in my Stratus and they work fine. It runs the tubes a little higher plate dissipation but still within the published limits.

2. I haven't tied yet the 274B rectifier.

3. The ST in 5U4G ST refers to the glass envelope shape. This is the classic 5U4G shape.

4. A source for tested 6N1P-EB(EV) is Tube Depot

5. A recent Stratus customer ordered a set of the Psvane 2A3-T and reports they're a nice improvement over the stock Shuguang 2A3B.

6. When buying tubes through the internet, try to find sellers who use more sophisticated tube testers and publish both Ip (plate current) and Gm (transconductance) for both sections of the dual triode. This is better than a figure of merit as found on many testers.

7. The Stratus produces 9.5Vrms with 8 ohm output impedance into a 50 ohm load. Reducing the step-down turns ratio to increase output voltage also increases the output impedance based on the turns ratio squared. It's not clear to me that this will provide improved results with the HE-6. At the recent CHANGfest meet I tried the HE-6 with the Stratus and found the combo played plenty loud for me with headroom to spare. YMMV.

Thanks Donald! Looks like I am gonna get to hear the Stratus at a DC meet in May. that is just a day before my b-day. if the sequester does not hurt us too much, I may ask my wife for Stratus for my b-day!

post #529 of 2334
Quote:
Originally Posted by fejnomit View Post

Personally I wouldn't worry about the driver tubes, like you said.  They're cheap anyway...

 

That first 5U4G sounds great - 56 and 56 is a perfectly balanced tube.  The second sounds like it's probably good too.

 

I hope Donald will chime in about the dangers to the amp. 

 

Personally I don't have a tester - I just try what I buy and hope for the best...  WITHOUT HEADPHONES ON WHEN I FIRE UP THE AMP.  Like I said, I learned that one the hard way...

I'll keep this in mind. Thanks for the tips!

post #530 of 2334
Quote:
Originally Posted by Donald North View Post

Answering several recent questions:

1. I tried a couple 5U4GB in my Stratus and they work fine. It runs the tubes a little higher plate dissipation but still within the published limits.

2. I haven't tied yet the 274B rectifier.

3. The ST in 5U4G ST refers to the glass envelope shape. This is the classic 5U4G shape.

4. A source for tested 6N1P-EB(EV) is Tube Depot

5. A recent Stratus customer ordered a set of the Psvane 2A3-T and reports they're a nice improvement over the stock Shuguang 2A3B.

6. When buying tubes through the internet, try to find sellers who use more sophisticated tube testers and publish both Ip (plate current) and Gm (transconductance) for both sections of the dual triode. This is better than a figure of merit as found on many testers.

7. The Stratus produces 9.5Vrms with 8 ohm output impedance into a 50 ohm load. Reducing the step-down turns ratio to increase output voltage also increases the output impedance based on the turns ratio squared. It's not clear to me that this will provide improved results with the HE-6. At the recent CHANGfest meet I tried the HE-6 with the Stratus and found the combo played plenty loud for me with headroom to spare. YMMV.

 

Thank you Donald for your input. 

post #531 of 2334

I remember Budx talked a little bit about the choice of feet for the Stratus.

 

I recently order a set of three alternative feet with wooden pads for the Stratus to replace the stock hemisphere shaped rubber feet. They are as shown in the picture.

 

 

I bought them for the look. And I have to say they look pretty nice on the Stratus. However, I was surprised when I noticed that these feet affected sound quality. After switching to these feet, I've noticed a bit better details, punchier bass, and small improvement in soundstage. They make the Stratus sound thinner though. What surprises me the most, however, is that I found noticeable microphonic after using these new feet and bad, which is very annoying. (Microphonic was never a problem with the stock rubber feet.)

 

Have anyone tried alternative feet on the Stratus? And what's your impression?

post #532 of 2334

There are entire schools of thought and raging debates about the right footers for equipment with some companies charging thousands for complete resonance control systems.  Of them all, I am a huge fan of Mapleshade products.  They are entirely reasonable price-wise when you consider what they do. The micropoint brass footers have an incredible effect on the sound of all components - the bigger the better, although they offer all kinds of sizes.  Most vibration control products wrongly assume the majority of the sound-killing vibrations come from outside the equipment and so they try to isolate it.  After decades of testing, MS has learned that the overwhelming majority of vibrations originate from inside the component itself and therefore any system worth its salt will focus on draining the vibration from the component first and foremost.  This is even more true of tube gear, where transformers and chokes and tubes all resonate.  Check out their website.  I can vouch for the way they work.  I will post some pictures of my set up when I get my camera back from the shop.

post #533 of 2334
Quote:
Originally Posted by fejnomit View Post

There are entire schools of thought and raging debates about the right footers for equipment with some companies charging thousands for complete resonance control systems.  Of them all, I am a huge fan of Mapleshade products.  They are entirely reasonable price-wise when you consider what they do. The micropoint brass footers have an incredible effect on the sound of all components - the bigger the better, although they offer all kinds of sizes.  Most vibration control products wrongly assume the majority of the sound-killing vibrations come from outside the equipment and so they try to isolate it.  After decades of testing, MS has learned that the overwhelming majority of vibrations originate from inside the component itself and therefore any system worth its salt will focus on draining the vibration from the component first and foremost.  This is even more true of tube gear, where transformers and chokes and tubes all resonate.  Check out their website.  I can vouch for the way they work.  I will post some pictures of my set up when I get my camera back from the shop.

Thanks, fejnomit. I'm tempted to try ... These micropoint brass footers are not inexpensive though. Which one did you get for the Stratus? They have both micropoint heavy footers and micropoint mega footers. And there are subcatogries. 

 

Look forward to the photos!

post #534 of 2334
Thread Starter 
Quote:
Originally Posted by econparanoia View Post

Have anyone tried alternative feet on the Stratus? And what's your impression?

 

You have asked the right person - fejnomit has tried almost everything, and he lots of good suggestions. In the meantime, here's a slightly different perspective.

 

When I tried the whole Mapleshade tower, with amp on Isoblocks on maple platform on brass feet, I found that it produced better quiet and imaging, but to my ears there was a filtering effect, an emphasis in the lower midrange. Now I have these under my Stratus

http://marigoaudio.com/isolation-feet/mystery-feet/

Fantastic, but expensive. Blacker, better definition both high and low, no emphasis, and extraordinary 3D effect, which to my mind means that they drain all internal vibration noise and maintain phase coherence. The maker, Ron Hedrich, has professional engineering experience in vibration isolation. I learned about them when Rdr_##  posted in this thread.

 

I found that more than half of that effect can be obtained very inexpensively by placing the Stratus on 3 Mapleshade Isoblocks

http://shop.mapleshadestore.com/prodinfo.asp?number=ISOBLOCK1-ST

with each Isoblock sitting on a Symposium Point Pod

http://www.symposiumusa.com/pointpods.html

 

That works much better than any set of cones or springs or roller spheres, to my ears.

 

Happy Listening!

smily_headphones1.gif

post #535 of 2334

Lower midrange is one of the areas that gets killed by vibration, so it would make sense that this range would be allowed to come through where previously it had been veiled...

I personally don't think the Mapleshades add anything, only take away...  I have heard good things about the Marigos too just never listened...

 

And in answer to which ones, the largest footers have the greatest effect and are the most stable, but $ and space play a role obviously. I have the largest, heaviest ones under my speakers, digital sources and PSUs.  Then I scale down.  Big ones are a little much for the desktop... When you add the height of the biggest isoblocks, platform and footers you're talking about lifting your Stratus as much as 10 inches off the desk!   I use them under external hard drives and monitors too... but I'm perhaps a bit extreme (in all things...)

post #536 of 2334
Quote:
Originally Posted by fejnomit View Post

Lower midrange is one of the areas that gets killed by vibration, so it would make sense that this range would be allowed to come through where previously it had been veiled...

I personally don't think the Mapleshades add anything, only take away...  I have heard good things about the Marigos too just never listened...

 

And in answer to which ones, the largest footers have the greatest effect and are the most stable, but $ and space play a role obviously. I have the largest, heaviest ones under my speakers, digital sources and PSUs.  Then I scale down.  Big ones are a little much for the desktop... When you add the height of the biggest isoblocks, platform and footers you're talking about lifting your Stratus as much as 10 inches off the desk!   I use them under external hard drives and monitors too... but I'm perhaps a bit extreme (in all things...)


Can you guys post some pictures to show how this all looks. Sometimes these things online are shown with nothing else in the picture to let you know their relative size. Would be even better to see them in a real system. THanks!

post #537 of 2334

One of the topics that has not come up too much in this thread is the effect of balanced vs SE and upgrading the HD800 cable in general. I've been rocking the stock cable since getting the HD800. Is it worth re-terminating the stock HD800 cable to a balanced 4 pin, for example?

post #538 of 2334
Quote:
Originally Posted by Cante Ista View Post


Can you guys post some pictures to show how this all looks. Sometimes these things online are shown with nothing else in the picture to let you know their relative size. Would be even better to see them in a real system. THanks!


Yes, pics please!

post #539 of 2334
Quote:
Originally Posted by Donald North View Post

Answering several recent questions:

1. I tried a couple 5U4GB in my Stratus and they work fine. It runs the tubes a little higher plate dissipation but still within the published limits.

2. I haven't tied yet the 274B rectifier.

3. The ST in 5U4G ST refers to the glass envelope shape. This is the classic 5U4G shape.

4. A source for tested 6N1P-EB(EV) is Tube Depot

5. A recent Stratus customer ordered a set of the Psvane 2A3-T and reports they're a nice improvement over the stock Shuguang 2A3B.

6. When buying tubes through the internet, try to find sellers who use more sophisticated tube testers and publish both Ip (plate current) and Gm (transconductance) for both sections of the dual triode. This is better than a figure of merit as found on many testers.

7. The Stratus produces 9.5Vrms with 8 ohm output impedance into a 50 ohm load. Reducing the step-down turns ratio to increase output voltage also increases the output impedance based on the turns ratio squared. It's not clear to me that this will provide improved results with the HE-6. At the recent CHANGfest meet I tried the HE-6 with the Stratus and found the combo played plenty loud for me with headroom to spare. YMMV.

Thanks very much Donald for the heads-up on the 5U4GB.  I was also wondering if the 500 ma figure was about right for the current into the 50Ohm load.  The reason I am wondering about this is that I think the current needs of these new ortho phones  are being exaggerated and perhaps so were (are?) the current figures I saw being bandied about when I last looked about 3 years ago.  

post #540 of 2334
Quote:
Originally Posted by budx3385 View Post

 

You have asked the right person - fejnomit has tried almost everything, and he lots of good suggestions. In the meantime, here's a slightly different perspective.

 

When I tried the whole Mapleshade tower, with amp on Isoblocks on maple platform on brass feet, I found that it produced better quiet and imaging, but to my ears there was a filtering effect, an emphasis in the lower midrange. Now I have these under my Stratus

http://marigoaudio.com/isolation-feet/mystery-feet/

Fantastic, but expensive. Blacker, better definition both high and low, no emphasis, and extraordinary 3D effect, which to my mind means that they drain all internal vibration noise and maintain phase coherence. The maker, Ron Hedrich, has professional engineering experience in vibration isolation. I learned about them when Rdr_##  posted in this thread.

 

I found that more than half of that effect can be obtained very inexpensively by placing the Stratus on 3 Mapleshade Isoblocks

http://shop.mapleshadestore.com/prodinfo.asp?number=ISOBLOCK1-ST

with each Isoblock sitting on a Symposium Point Pod

http://www.symposiumusa.com/pointpods.html

 

That works much better than any set of cones or springs or roller spheres, to my ears.

 

Happy Listening!

smily_headphones1.gif

Thank you, budx and fejmomit, for doing a lot of trails and sharing impressions and very helpful suggestions! 

 

I am thinking about trying one of the followings first:

 

1). A set of three Micropoint heavy footer (not the Triplepoint one).

2). A set of three Isoblock with the Symposium Point Pod.

 

The table I put my Stratus on is heavy, stable, and made by hardwood. Do you guys think it is still necessary (or beneficial) to get a Maple platform (or similar platform)? Also, I am wondering how you installed these footers. Did you use adhesive glue or double-sided adhesive tape to adhere the footers to the Stratus? Or, did you simply place these footers under the unit?

 

BTW, I just got a pair of Shuguang Black Treasure 2A3s. And I like them a lot! Compared with the EML 2A3 mesh plates (which I've been enjoying), these Shuguang tubes are a little bit less detailed but less fatiguing. To my ears, EML 2A3 mesh plates and Shuguang Black Treasure 2A3s provide about the same amount of bass. However, Shuguang's bass is rounder, while EML's bass is tighter. Shuguang sound "wetter", and I think they do a better job (by a small margin) with female vocal. Overall, I am happy with both EML and Shuguang Black Treasure.

 

I do find that the Shuguang Black Treasure runs hotter than the EML mesh plate. Do you think this is normal? (I hope Budx could chime in here smily_headphones1.gif )

 


Edited by econparanoia - 3/8/13 at 8:01pm
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