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DNA Stratus 2A3 amplifier - first impressions - Page 5

post #61 of 1994
Quote:
Originally Posted by budx3385 View Post

 

davidross, I haven't heard the EC 2A3, but I have heard the EC Balancing Act with KR PX4s, which produced a mighty clean and juicy sound on LCD-2, but really did not work as well with any other headphone we had on hand to try. I feel quite comfortable in saying that the Stratus with NOS RCA 2A3s, a cryo'd NOS 5U4G and 6BQ7a produces a very comparable, clean, powerful, fully extended, and emotional sound image with every headphone I've tried. My favorite is still the T1.

Allow me to disagree w/ this.  I've used the BA w/ multiple samples each of T1's, 880's, LCD2's r.1+r.2, LCD3's, HD800's, HD600/650/700's, HP2's, Hifimen and more.  I have never run into this problem you describe.  I think you might not be liking the KR PX4s in relation to those phones or the actual signature of the phones in question.  Those are very clinical tubes from what I recall.  I love Donalds work and think the Stratus is great but no way is it more clean and extended from top to bottom than the BA w/ the stock tubes in the Stratus.  Perhaps your proprietary compilation of tubes kicks it up quite a bit which is the only way I could imagine hearing what you claim.  I'm pretty sure there's no way the transformers in the Stratus outperform those in the BA and it's high frequency heater either.  You should hear more noise from the BA but it's from the source in front or the track mastering, not the amp.  That's transparency IME.  If you don't want to hear all that stuff, then Eddie current is not the way to go.

post #62 of 1994
Thread Starter 

^ Thanks for opining for BA. I certainly meant no disrespect. I think Craig's HF filament loop is very innovative, and I know that there are many fans of his half-silver transformer. He is an honorable and creative member of our community who actively supports local meetings even here in Phoenix, and his products are top-notch.

 

Nevertheless, even though both of my local audiophile friends decided that they prefer their KR-PX4 BA's decked out with complete SAA cabling and LCD-2s to the Apex Pinnacle when we had it here for comparison, both also felt that the Pinnacle outdid their units in that it matched well with every headphone we tried, including the LA7000, HD800, DT880 and T1, whereas their KR-PX4 BAs do not. 

 

I have only heard the BA in that configuration. I'm not surprised to hear that the BA sounds great with lots of headphones when outfitted differently.

 

I certainly agree with you that the Stratus does not compete outfitted with its stock tubes, though that configuration may serve some folks well. Somehow Donald succeeded in selecting a combination of components that enable the Stratus to sound "juicy", as he calls it -- my word is presence. The KR-PX4 BA I heard didn't have that quality, to my ears. Outfitted with the cryo'd NOS 5U4G and the NOs RCA 2A3 blackplates together with the cryo'd NOS 6BQ7a that I have installed here, the Stratus produces clean, powerful, transparent and "juicy" music that is at least level with the KR-PX4 BA LCD-2 setup, and to my ears, more satisfying and very very close to the level of the Pinnacle. Of course, that's all based on my memory for SQ, and I am just as fallible as anyone else.

 

I invite you to try this combination and share your impressions. Orange Cty is mighty huge, but maybe you could visit Donald! Were you at  the Orange Cty HF meet last December where Donald showed off his prototype?

post #63 of 1994
Quote:
Originally Posted by budx3385 View Post

 

I invite you to try this combination and share your impressions. Orange Cty is mighty huge, but maybe you could visit Donald! Were you at  the Orange Cty HF meet last December where Donald showed off his prototype?

Oh I agree, his amp is juicy.  I think it's great.  Equally transparent to the BA is another thing but we'd be splitting hairs.  The KR's are the source of that thin, lack of juicyness.  Purrin runs some Old vintage balloon PX25s for juicyness w/ a BGRP 6SN7 driver.  I actually prefer the BA over the Pinnacle tbh, too bright and harsh for my tastes.  Not sure I'd even consider it a tube amp really.  There's a sort of SS flavor to Pete Millets amps that don't work as well for me.  I'm just a bit lost as to what "matching very well" means exactly.  It's rather nebulous for me to process.  Power?  Sonic synergy?  

 

Yup I've heard Donald's amp 3 or 4 times now at different meets.  Always in meet conditions and w/ stock tubes.  Was hoping to have an extended listen under better conditions to confirm a few thoughts but haven't heard back yet.

 

Craig and Donald are two of my favorite amp builders from a list of maybe five total.


Edited by Anaxilus - 6/4/12 at 6:54pm
post #64 of 1994
Thread Starter 

Quote:
Originally Posted by Anaxilus View Post

Yup I've heard Donald's amp 3 or 4 times now at different meets.  Always in meet conditions and w/ stock tubes.  Was hoping to have an extended listen under better conditions to confirm a few thoughts but haven't heard back yet.

 

I hope those conditions can be arranged!

 

I spent lots of time and money modifying my DNA Sonett, and IMHO, it is just as crystal clear as the Pinnacle. But replacing the stock tubes on the Stratus is all it took to have an amp that is nearly as transparent, considerably more powerful, and endowed with loads of "juicy" presence - the stuff of goose bumps, heart pangs and tears.

 

And obviously, since I pre-ordered the very first marketable Stratus, I'm a committed fan of Donald's choices in components - especially transformers, which he will say himself has a lot to do with the "juicy" DNA sound.

 

So, OK, full disclosure ---  I readily admit to being a bit enthusiastic! and I hope you get to hear it again!

 

dt880smile.png

post #65 of 1994

I know Craig likes the Electra-Print transformers which are good, however I prefer the sound provided by my custom ones made by Edcor. Their transformers sound more engaging to me. Regarding heating the filaments on the 2A3s, Craig's choice to use ultrasonic AC heating is intriguing. I'm curious to measure the output spectrum with my AP to see what residual high frequency artifacts may be present. I chose a different approach to heat the filaments in sonically benign manner by using a DC supply with user adjustable hum nulling pots to account for the manufacturing tolerances in the filament structures. In the end, the proof is in the sound and to each their own for finding their preferred sound. beerchug.gif

Quote:
Originally Posted by Anaxilus View Post

 I'm pretty sure there's no way the transformers in the Stratus outperform those in the BA and it's high frequency heater either.

post #66 of 1994
Quote:
Originally Posted by Donald North View Post

I know Craig likes the Electra-Print transformers which are good, however I prefer the sound provided by my custom ones made by Edcor. Their transformers sound more engaging to me. Regarding heating the filaments on the 2A3s, Craig's choice to use ultrasonic AC heating is intriguing. I'm curious to measure the output spectrum with my AP to see what residual high frequency artifacts may be present. I chose a different approach to heat the filaments in sonically benign manner by using a DC supply with user adjustable hum nulling pots to account for the manufacturing tolerances in the filament structures. In the end, the proof is in the sound and to each their own for finding their preferred sound. beerchug.gif

 

Well, I've been dying to hear the Stratus under better conditions as you know.  We don't have a 2A3 but your welcome to measure the BA..

post #67 of 1994
Quote:
Originally Posted by budx3385 View Post

santacore, thank you very much. I won't be tempted by those any longer.

 

The EML meshplates have about 80 hrs now, and they have changed a bit. They are controlled, fast, very clean and accurate - but dry. They sounded lifeless at first, so they have gained a bit of emotional juice, but they still need to loosen up and relax. When I replace them with the RCAs, the presence returns in spades. Same with the rectifier. I will keep on burning.

 

I'm very tempted to order a pair of Sophia Electric Princess 2A3s. If you have any experience with those, please let me know.

 

There are quite a few comments on the WWW about the dryness of the mesh plates.  A lot of people who have heard both prefer the carbon plates.  I've listened to neither.

post #68 of 1994

It's with great pleasure that I announce that DNA Stratus serial # 3 is ready and in process of break in by Donald.  smily_headphones1.gif

 

And yeah it's gonna be mine. biggrin.gif

 

Will be plugging HD800, HD650, T1, HE-500, Denon D7000, DT880 (250 ohms) and maybe a LCD-2. wink.gif

 

As I'm on vacation, sonic impressions only next month though...

post #69 of 1994

congratulations madbull!! that means mine will be next. tongue_smile.gif

post #70 of 1994
Thread Starter 

ditto!  We will be looking forward to your comments!

post #71 of 1994
Thread Starter 

The EML 2A3 meshplates have >150 hrs now, and they have changed considerably. They now provide quite a bit of emotion and presence, and the sound is still as clear, controlled and well-defined as before. They still provide impact. I would no longer describe the SQ as dry, and there is audibly more "you are there".  This using the cryo'd NOS 5U4G, which provides a more liquid sense of air than the EML rectifier.

 

The NOS 1940s RCA dual S-shaped blackplates still sound smoother, more liquid, and more emotionally involving, though with less clarity and micro-detail. The 3 string players in the Hyperion release of Brahms Piano Quartet No 1 Op 25 with Marc-Andre Hamelin are more difficult to separate when playing in unison than with the EMLs, but the music flows and so I am actually not interested in picking out detail, because I am enjoying the music-making. Same for the solo piano - easy to enjoy and "feel" the music in a wholistic way with the NOS tubes. The "impact" of the piano key strikes don't quite sound real with the EMLs. To my ears.

 

George at tubesusa said the tubes should have been "well broken in" by 100 hrs, but I will continue to give them extended playing time, both with music and with the XLO burn-in CD.

 

And the Sophia Electric Princess 2A3s (also meshplate) that I ordered should arrive by tomorrow.

 

Quote:
Originally Posted by Frihed89 View Post

 

There are quite a few comments on the WWW about the dryness of the mesh plates.  A lot of people who have heard both prefer the carbon plates.  I've listened to neither.

 

Thank you very much, Frihed89. That could be my next direction. 

 

Oh, and one more comment. I happen to know that Donald spent time and effort looking for and testing out different types of feet, because I offered a few suggestions at the time. The ones he chose provide an outstanding level of vibration isolation on my rack - the 2A3s are notoriously microphonic, which you can easily verify with a light fingernail tap. The feet on the Stratus are so well-chosen and have just the right balance between support and compliance, that I need to rap the shelf that it sits on quite hard in order to cause tube ringing. From the next adjacent shelf, I can barely produce any sound. (and this with a $300 Sanus rack from Audio Advisor).

 

The only drawback is that they are short, and my well-aged fingers have a hard time slipping underneath to lift or move the unit. I guess if I were still doing rock-climbing, I would have retained sufficient finger-tip strength to lift the Stratus anyways!

 

But I guess that's really just kvetching after all ....


Edited by budx3385 - 6/8/12 at 2:31pm
post #72 of 1994

Hi Bud, you might want to look into these. I currently use them under my DAC and the Sonett. The difference under my tubed amps in the main system was stunning. Under the Sonett, the effect wasn't suble, but since it's a headphone system, the effect was more of refinement, clarity and purity. Strongly, strongly recommended! 

 

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

 

By the way, I used their tuning dots on my Merlin's MXe's for improved midrange focus!

 

Quote:

Originally Posted by budx3385 View Post

Oh, and one more comment. I happen to know that Donald spent time and effort looking for and testing out different types of feet, because I offered a few suggestions at the time. The ones he chose provide an outstanding level of vibration isolation on my rack - the 2A3s are notoriously microphonic, which you can easily verify with a light fingernail tap. The feet on the Stratus are so well-chosen and have just the right balance between support and compliance, that I need to rap the shelf that it sits on quite hard in order to cause tube ringing. From the next adjacent shelf, I can barely produce any sound. (and this with a $300 Sanus rack from Audio Advisor).

 

The only drawback is that they are short, and my well-aged fingers have a hard time slipping underneath to lift or move the unit. I guess if I were still doing rock-climbing, I would have retained sufficient finger-tip strength to lift the Stratus anyways!

 

But I guess that's really just kvetching after all ....


Edited by Rdr. Seraphim - 6/8/12 at 3:50pm
post #73 of 1994
Thread Starter 

Hi Mark - great to hear from you here. Thank you very much for this suggestion. I felt a bit uncomfortable with that webpage, though, because it didn't really provide any description and the fotos of the two sorts actually looked like the same fotos turned 90 degr.

FYI, I installed Ultra SS Stillpoints under my VSMs, and last I heard, Bobby P was still auditioning them himself. And I tried those and lots of things under my Sonett, and finally settled on these easy-to-use and rather inexpensive feet

http://shop.mapleshadestore.com/Original-Isoblock-1s/productinfo/ISOBLOCK1-ST/

 

 

 

On a note of more general interest, I listened to the Stratus with the EML meshplates (burned >160 hrs) for ~3 hrs yesterday, and enjoyed it very much, more than with the NOS blackplates. Their transparent, detailed, dynamic, controlled and solid presentation now has enough emotional presence to be very satisfying.

 

But the Sophia Princess 2A3 meshplates arrived, and so they are now burning in. Their SQ has been different every time I peeked in, so I will wait to say anything.


Edited by budx3385 - 6/9/12 at 1:37pm
post #74 of 1994

Ron is not much into marketing--being a scientist type--and frankly, the products are sufficiently similar that either would do. Mapleshade Isoblocks also saw time in my system, and are still used under the end grain cutting board platforms! Good choice! The amp and DAC sit on the Marigo Labs Mystery feet. The combination is world class. 

 

I'm considering the Stratus, and watching this space very carefully!

  

Originally Posted by budx3385 View Post

Hi Mark - great to hear from you here. Thank you very much for this suggestion. I felt a bit uncomfortable with that webpage, though, because it didn't really provide any description and the fotos of the two sorts actually looked like the same fotos turned 90 degr.

FYI, I installed Ultra SS Stillpoints under my VSMs, and last I heard, Bobby P was still auditioning them himself. And I tried those and lots of things under my Sonett, and finally settled on these easy-to-use and rather inexpensive feet

http://shop.mapleshadestore.com/Original-Isoblock-1s/productinfo/ISOBLOCK1-ST/

 

 

 

On a note of more general interest, I listened to the Stratus with the EML meshplates (burned >160 hrs) for ~3 hrs yesterday, and enjoyed it very much, more than with the NOS blackplates. Their transparent, detailed, dynamic, controlled and solid presentation now has enough emotional presence to be very satisfying.

 

But the Sophia Princess 2A3 meshplates arrived, and so they are now burning in. Their SQ has been different every time I peeked in, so I will wait to say anything.

post #75 of 1994
Sure glad I have a bunch of those Mapleshade blocks sitting around.
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