Donald North Audio — Owners Thread

So I got a NOS pair of 2A3 tubes from a reputable seller and have an intermittent noise in 1 of the tubes. For reference, seller has already given suggestions, etc. but want to borrow SBAF collective knowledge:

- Noise is usually a scratching etchy noise in a somewhat random pattern only in 1 channel, sometimes the noise resembles white noise, sometimes noise just sounds like random electronic noise, and sometimes it's a mix of the above.
- Noise follows the channel for the 2A3 tube. Swapped rectifier and input tubes too just to be sure, made no difference.
- 2A3 tubes measure fine
- Noise was constant when tube was new, seller suspected small flake of debris on something inside, recommended firm (but not too firm) taps of glass against a table and then a few more solid taps but with the base against the table. Repeat 1 or 2 more times if needed (I did). Burn in at least 24 hours (not necessarily continuous). After doing the above, the noise is now intermittent. Noise is more likely to happen after the amp has been on for a few hours.
- Noise does not change with different volume (I can even disconnect inputs, same noise).
- Noise will always build up to a crescendo and then suddenly drop out.
- Checked power, moved wall sockets, etc.

Does the tube just need more burn in? Or is it time to return the tube?

 

Return it if you still can, noisy tubes don't get better.

 

Brent Jessee. He has already said he is willing to provide a refund (at multiple points throughout the process no less and has been very helpful throughout the process). Seems like SBAF doesn't think I'm overlooking anything either.

I'm going to give it one more day or two to see if anyone else has a solution given that when these tubes work properly they sound great. Otherwise I'm returning. It's been almost 100 cumulative hours of burn in by now - as far as I know 100 hours is enough burn in for tubes. That and I am hoping someone would say I'm overlooking something or that the tubes just need X more hours of burn in given that the noise has gone from constant to intermittent.

 

Send it back. I've bought from Brent for well over 10 years, he's as solid as it gets. Sometimes a truly new NOS (if Brent says it's NOS I believe him) tube will be a bit noisy at power up, but it goes away after a handful of hours in my experience. At near 100 hours, it should be quiet.

 

I don't see any pricing listed for the Starlett. can someone confirm pricing?

 

Could be a defective tube or could be that it needs some burn in time. If you're willing, I fix noisy tubes by running a hot soldering iron up and down each pin for about 30-45 seconds. I've fixed 4 out 5 tubes this way and can almost fix all the tubes by doing it a second time. The rest are just a lost.

Hold the tube with pins facing the bottom, don't touch the bottom of the pins with the soldering iron (it contains solder you don't want to melt) and go all the way around. Give it a try after and see if it works.

 

In case the tube is vibrating, carefully take a towel or something and gently grip the tube. If it has an impact it's microphonic and nothing you can do.
S plate tubes seem to be prone to this.

Keep in mind the tubes might be fine in a different amp, I have a few examples of tubes that are fine in one amp and hum in another,seems to be dependent on how the tube is biased if it's prone to hum.

Anyway, send them back, wishing for tube hum to go away isn't going to help. Even if it does for a while there's no guarantee it won't come back.

 

Just an update - tried the soldering iron trick. It made the noise go from 3 types of noise (individually or a combination of) to just white noise only. However, the white noise became more constant than the noise before. Adjusting the variable resistors next to the 2A3 sockets didn't help either. Tried to do the tapping thing 1 last time per Brent Jessee instructions and that didn't work at all this time (where as before it helped). Using a towel to test for microphonics - wasn't the culprit. Tubes have been returned without issue.

For reference, this would be my 2nd pair (in a row) from Brent that has had a bad tube. He has been great both times about the return. I've bought many other tubes from him before and none have had issues. I have full confidence buying tubes (especially expensive NOS tubes with no mfg warranty) from him in the future.

 

On a completely different note - post #379 I mention I have incoming input tubes. Here are some brief thoughts on rectifiers too:
EDIT 12/9/19: Added/reformatted a little more info on individual input tubes after more listening and Raytheon 5U4G

5U4G - tried stock Winged C gray plates (Svetlana I think), 3 different RCA tubes, 1 Tung Sol, 1 EML Mesh. May try to find a GEC 5U4G later if one shows up at a reasonable price.
- My overall favorite is (still) the RCA. Matches the voicing and musicality of the amp very well. Balanced all around with a hint of warmness and smoothness. Readily available for $50 or less and last a long time too. Didn't notice much (if any) of a difference between the 3 individual tubes.
- EML mesh is great too. Brings out the dynamics a little bit but changes the overall feel of the amp a bit. Unfortunately ~$250 and not necessarily "better" than a <$50 RCA. Probably still worth it IMO and IIRC Donald and many other DNA owners use them too. For me these are 25% of the time, RCA 75%.
- Tonality with with Tung Sol (vintage US production, not modern reproduction) seemed slightly off but good overall as well.
- Stock 5U4G wasn't bad, but it was just a little too much of the house sound for my personal preference.
- Raytheon - Not a huge difference vs RCA, but slightly drier sounding, a very small loss of musicality, and possibly a small loss of resolution and a touch more "evenness" in the sound (these last 2 are so small that it may be placebo).

Input tubes:
6N1P - my preferred tube for this amp. Not a surprise given Donald's tuning. After listening to other tubes more, with 6N1P, you *think* you hear some of the typical issues with Russian 6N1P tubes (thin and slightly harsh sound yet overly warm at times and not quite right in other ways) - but then the issues never really come and you realize this amp really is voiced/tuned for this tube.
-No comments regarding individual variants yet.

6CG7 - none of them sounded quite right with Stellaris (note this is the default input tube for the Starlett and complaints below did not apply when I listened to Starlett at last 2 meets)
Negatives first: None are big issues, minus 0.5/10 at most in any one area. Amp loses some musicality (regardless of other tubes used). Overall everything felt a little muddy with 6CG7 versus other 2 tube types - transients were slower (think slope of a line not being as steep) and edges were too rounded, slight blur to sound, slight loss of detail. Stage seems to shrink with all 6CG7 tubes vs 6N1P.
Flavor stuff: Overall much more relaxing sound vs 6N1P, like sit on the couch with a beer relax, not like sloppy relaxed. Make amp quieter (6dB).
Positives: The one big benefit of 6CG7 is the tubes all sound more even than the various 6N1P I have. I don't think I'm about to hear 6N1P negatives and overall the sound is more even throughout. Westinghouse and Sylvania tubes were especially good this evenness.

- Westinghouse - Upper mid and mid bass too forward. Highs and middle mids seem recessed. Something else also sounds off to me but I can't place my finger on it. Transients and edges slightly better than other 6cg7.
- Sylvania - Similar to Westinghouse, but had a tiny bit more of the muddy / less "sharp" in the sound. A little less separation and clarity between instruments. Random parts of the bass and upper register sound muffled like I put a thin beach towel on 1/3 of an octave here and 1/4 an octave there.
- RCA - Was overall OK for a little bit despite something I couldn't place being off, didn't excel in any one area. I probably liked this tube the most for Stellaris. However, individual tube seemed to have developed odd intermittent issues.
- CBS - Tiny bit of bass boost and felt randomly weird at times, but bass not messy or slappy, just slightly loose due to being muddiest of the 6CG7 (relatively, still overall minor). Was actually more musical to me than the other 6CG7.

6BQ7Z - None were quite right for Stellaris, but again, like 6CG7 not big issues, minus 0.6/10 in any one area at most. Main issue is sometimes you lose micro (details, dynamics), lose some of the plankton, and timbre and tonality are randomly off for some things. Slightly deceiving as these tubes sound "more" correct vs 6N1P initially, but after listening more you hear the issues. Difference between individual 6BQ7Z tubes smaller than difference between 6CG7 tubes.
- Surprisingly though, the GE tube was surprisingly good and evenhanded (in my limited experience with GE tubes I've never heard a really good one before, only exception being ones for ZDT Jr are OK in that amp).
- RCA tube was worst offender of all issues above.
- Sylvania was tonally similar to GE, but a little more slam and dynamics, a little more forward sounded, a little less bloom and some instruments seemed to decay slightly too fast.
- No comments on CBS tube as it has noticeable hum.

Conclusion
In general, I find the input tubes make the biggest difference on this amp. However, with certain tubes or combos, the rectifier or power tubes can easily make a bigger difference. Overall, as I've mentioned before here, tubes don't make as much of a difference with this amp vs many other amps. Caveat being I haven't heard THAT many 2A3 in this amp yet, especially a lot of the $500+ modern production 2A3 tubes.

With all of the above being said, Stellaris with stock tubes is still one of the top 3 headphones amps I've ever experienced despite the house sound not matching all of my audio preferences.

 

fp627, you might like to try a RCA 5U4G with black smooth plates made in the early to mid 1940s.nThese are WW11 tubes and are supposed to be better than later ones. Its a hundred dollar tube on Ebay. I also like the war time RCA 2A3s with black plates. The cream of the crop for those are mono plate tubes that go for $1500/pr on Ebay. My current faves are Psvane Acme Supremes 2A3 with the EML 5U4G and a Ruby Tiger Select 6N1P input tube. I also like the KR 2A3s. Good NOS sounds very nice, but these tube combos are more dynamic and less tube sounding.

 

So... got my exchange pair of 2A3. 3rd times the charm with the noise... but... I think one of the tubes is slightly microphonic:

Am I being too picky?
There's no noise when I just listen to music or do stuff like type, etc on the same table. However, if I tap the table the amp is on (a small cheap ikea particle board table) with anything more than a light force I get a low level ringing noise for about 1-2 seconds in the tube (keeping in mind the Stellaris itself has big thick rubber domes for feet and weighs a considerable amount). If I even put something down as light as a cell phone on the table (not drop, just gently put down like you normally would), same noise. Adjusting the variable resistor for that socket doesn't help and I get microphonics every time I touch the variable resistor as well. Lastly, if I grab the tube with a towel and repeat any of the above, no noise.

Tube sounds great otherwise, but I would hate for the microphonics to get worse less than a few hundred hours later given how much these tubes cost.

If it makes a difference the slightly microphonic tube is listed as used with the paperwork I received (not NOS) but it matches the other tubes listed as a NOS tube. No noise at all with other tube, none of the other 2A3 I've received from Brent have had this either.

 

No, good NOS 2A3s are harder and harder to come by, over the years I've had 17 pairs of 2A3s, just one tube was microphonic and a bit noisy. DNA amps are not prone to microphonics.

Sounds like you're a good candidate for tube dampers. Herbies work well but hellishly expensive, see if you can find some cheap ones on ebay or go industrial with water pipe clamps:

 

No more freaking adaptors. Got the Yamamoto UX4-B4 base, all the pops, pings, random static is gone, all that remains is pure bliss.


The more I listen to PX4 I'm reassured I was right to sell the bulk of my 2A3 collection from 17 at its height to just 5 pairs.

There's just one more thing bugging me with the Stellaris, the hum pot. It's undeniable in the signal path and it's a cheap pot. I've never had to use it except for tubes with issues and even then it didn't kill the hum.

To remove it or not?

 

Ask Donald. He designed the amp and would know. I would love to know what 5 pairs of 2A3 you kept.

 

4xAVVT mesh 2A3 with another single in case one blows up and sylvania dual flat plate for testing and a reference of old 2A3 sound.

 

Just got my DNA Sonett 1 today (bought from a member here). Very happy with the pairing with HD 800SD. For me the sound lives up to the reputation. I was about to give up on the HD 800. This setup provides a very nice counter point to my other setup. I would definitely think about buying a Higher Level DNA amp in the future. The Sonett is already enough to keep me happy.

Cheers thanks to SBAF community for pointing me in the right direction.

 

2A3 update - got working early 40's RCA tubes after another swap out (both spring top, 1 has fishing pole supports for top mica, 1 doesn't).

Springtops sound very similar to non-springtop 2A3 but better separation, slightly sharper transients, and slightly better technicalities in about every way, from stage to dynamics to resolution. Springtops are a little bit warmer though if you don't want that in the amp. Neither capture that very musical sound and lush feeling of stock tubes but present a more neutral sound and both have better technicalities.

Pretty happy with existing tubes for now, may try 1 or 2 new 2A3 tubes and input tubes later next year after obtaining another amp and DAC.

 

Having tried the Stellaris at @m17xr2b place, I would definitely agree that chasing the 2A3 dragon isn't worth it. While I will admit the AVVT mesh 2A3 was indeed resolving, I much preferred the PX4 tubes in the Stellaris especially with the ECC40 input tube. The PX4 thickens the sound a little bit without losing any dynamics or layering.