[fjhuerta]

So, here are my impressions after doing some things to the amp.

1) Stiffer power supply. I bought a 4A 6V regulated power supply.
No changes whatsoever. The little wall wart included isn't a real factor in how this amp performs.

2) A 6V battery.
Lower noise floor. But not by much. Performance is pretty much the same.

Here are my findings.

1) The amp hates low impedance headphones with a passion.
2) The amp works better than an X-Can V2 with higher impedance headphones, except for some noise I can't get rid of.
3) The amp is far, far more powerful than most of the Fiio products you can get for twice the price.



Theses graphs show how the NobSound behaves when not loaded with any headphones (blue trace) vs. with a battery supply and the upgraded power supply (green and white traces) with a set of Fiio EX-1 headphones connected.

The amp really suffers with the EX-1s!

Likewise. Worst performance comes when battery powered and loaded with the Fiios.

Quite a noisy amp. When battery powered, it's a bit quieter.

Intermodulation distortion, again, is worse when battery powered.

Looks terrible. But...

 

[fjhuerta]

Things change for the better with a full size can. I connected my AKG 712 Pros to the NobSound and Fiio Kunlun. Here's what I found.

The Fiio Kunlun is flatter, but the NobSound doesn't exhibit anymore the terrible frequency deviations it had with the Fiio EX-1 in ear. I guess the NobSound has a greater output impedance than expected.

Once again, the Fiio is better than the Nobsound. There's less noise below 3 Khz. There's a tiny bit less of noise when the NobSound is battery powered, but nothing special.

Having said that, the Kunlun has tremendously higher THD numbers, by a factor of more than 10. So, although the Kunlun is a more accurate amp, it simply can't power the AKG's as well as the NobSound. Strange, because I thought 300mW would be more than enough for the AKGs. I was wrong.

I'd definitely use the NobSound instead of the Fiio Kunlun for the AKGs.

 

[fjhuerta]

Things change for the better with a full size can. I connected my AKG 712 Pros to the NobSound and Fiio Kunlun. Here's what I found.

The Fiio Kunlun is flatter, but the NobSound doesn't exhibit anymore the terrible frequency deviations it had with the Fiio EX-1 in ear. I guess the NobSound has a greater output impedance than expected.




Once again, the Fiio is better than the Nobsound. There's less noise below 3 Khz. There's a tiny bit less of noise when the NobSound is battery powered, but nothing special.




Having said that, the Kunlun has tremendously higher THD numbers, by a factor of more than 10. So, although the Kunlun is a more accurate amp, it simply can't power the AKG's as well as the NobSound. Strange, because I thought 300mW would be more than enough for the AKGs. I was wrong.

I'd definitely use the NobSound instead of the Fiio Kunlun for the AKGs.

 

[fjhuerta]

And here's the NobSound (battery and Wall-Wart powered) vs the X-Can V2.

The X-Can V2 is a similar design, after all - a hybrid with no tube preamp, but rather a tube buffer using a 6922 tube. It cost $299 IIRC in 2000. The Nobsound cost me $35 on eBay a couple of weeks ago. So, let's see.

YIKES. This is evil. The X-Can, with the loaded AKG, looks like a smiley face EQ next to the flatness of the Nobsound. Strangely enough, I'd have expected at least a similar curve out of both of them, because of impedance interaction between headphone and amp. The X-Can is simply all over the place. "Sounds exciting" would be my first guess as to how the X-Can behaves with the AKG.

Once again, there's too much noise on the lower end of the NobSound, but the X-Can has more noise in the most sensible range of our hearing, and it has a weird 5 KHz bump that is noticeable on other graphs. The NobSound is actually quieter.

Note: The NobSound was pretty noisy with the Fiio EX-1. The AKG 712Pros don't make that noise so evident.

The THD sweep gives the nod to the X-Can. It has lower distortion levels than the NobSound. The NobSound while battery powered has lower distortion levels than when powered wiht a wall wart.

The X-Can has higher THD than the NobSound, while battery or wall wart powered.

The NobSound has better dynamics all around than the X-Can.

 

[fjhuerta]

So, there you have it. For $35, you can have a tube buffered SS amp that can actually power your big headphones with ease. It's better (IMHO) than a $299 circa 2000 amp, and it can power hungry headphones better than $100 Fiio amps.

It's quite a bargain, provided that you don't use it with low impedance or sensitive cans. It loves Sennheiser HD600s and AKG 712 Pros. It's a bit noisy in the low end, and you'll probably notice it (then again, maybe not). But it's pretty flat, it's distortion is kept on check, and it has tons and tons of power.

I'd definitely use it with a sealed battery for best performance. And it looks cool. I'll take a pic later, the battery is the same size as the amp!

 

[TheBIGKill1998]

Good job dude!

very interesting results you got there!

Im using this amp currently with my new beyerdynamics dt 770 pro 80 Ohm.
I think that also is a nice combo.

i wish i had the equipment to measure all that kind of stuff.
because i would really love to see how my mods on the nobsound perform.

 

[daySpring]

I've been using this little beast for little over a month now to drive T1.2, HD650, HE400i, K702 etc. Gotta say, after getting a $15 6V3A (dialed in) wall wart and getting rid of the annoying power noise that used to creep in after the amp has been left on for more than an hour, this is my all day driver for high impedance cans. Magni2 and M-stage HPA2 are rarely seeing any play time.

The stock 6j9p tubes are very 60s 'tube' sounding, warm but lots of distortion (read: not detailed) and tends to emphasize the fundamental tone and sound sort of overdriven. Rolling in a couple of NOS Philips Miniwatt SQs really cleaned up the sound.

The volume knob tough, seems to have no effective gain past the 2 o'clock position. So, Even though it is quite powerful, not as much as I first thought it was since I couldn't get past 9 o'clock on most cans with digital volume set at 100% in Foobar2k. On the bright side, I don't own a HE6, so not really worried about drive such cans.

Looking for recommendations for tube rolling for my old HE400 with Audeze vegan pads. Just like with the Magni2, this NS-08E gets quite sibilant at a little higher than regular listening volume. Need to tame that and pump a bit more tight sub bass that is sort of rolled off with the vegan pads.

 

[Balder]

Hi guys!

Thinking of buying one 08, but i use, and love, my Shure SRH940 - with an imp of just 42 ohms! Those of you who followed the somewhat "infected" debate when they came on the market in 2011, may remember that some claimed they were "Godlike", others just discarded them as booring, bass fatigued and to bright... bla bla... I bought them back in 2013, and they suit me fine. But they can be to analythical at times, and despite the low imp - they are "picky" on amps. So i was thinking maybe a "tube-hybrid" can make them a little more rock'nroll, live and smoothen them? I have read the whole thread and if i have got it right = 08 likes a heavy, imp and load? So are they right for Shure940? Or should i look at something like smsl sap vi, about the same price for me (ie SS OP-Amp "based")? I love to experiment, so maybe there is some tweaks that will make the combo Nob 08 + Shure to work? Anybody tried those HP on the 08?

Going to place a order for "an" HP-Amp at the end of July, in that price range up to $50.... so is it a bad idea to get the Nob 08, in my case? (no plans for a HP upgrade anytime soon).

Cheers/T.

 

[TheBIGKill1998]

Hi guys!

Thinking of buying one 08, but i use, and love, my Shure SRH940 - with an imp of just 42 ohms! Those of you who followed the somewhat "infected" debate when they came on the market in 2011, may remember that some claimed they were "Godlike", others just discarded them as booring, bass fatigued and to bright... bla bla... I bought them back in 2013, and they suit me fine. But they can be to analythical at times, and despite the low imp - they are "picky" on amps. So i was thinking maybe a "tube-hybrid" can make them a little more rock'nroll, live and smoothen them? I have read the whole thread and if i have got it right = 08 likes a heavy, imp and load? So are they right for Shure940? Or should i look at something like smsl sap vi, about the same price for me (ie SS OP-Amp "based")? I love to experiment, so maybe there is some tweaks that will make the combo Nob 08 + Shure to work? Anybody tried those HP on the 08?

Going to place a order for "an" HP-Amp at the end of July, in that price range up to $50.... so is it a bad idea to get the Nob 08, in my case? (no plans for a HP upgrade anytime soon).

Cheers/T.

Im using mine with my 80 Ohms Beyerdynamics DT 770s. Im totally happy with the combo. Im not sure how much the linearity and noise and such change between 42 and 80 Ohm... so i cant tell you very much about it.
From my experience i can only say, that this amp, is totally recommendable.

 

[TheBIGKill1998]

After i had my volume (by accident) turned up completely, whilst my 80Ohm Beyerdynamics where plugged into this amp, i wonder if the max output power of this amp damaged my headphones.

Is it possible that the max output power of this amp (1100 mw on 32 ohm load, accodring to amazon) can damage 80Ohm Headphones?

 

[Balder]

Thank's for the reply "TheBIGKill1998"!

If you feed nearly a whooping 1 W into a headphone, that's probably designed to handle about 300mW, you can definitly "burn" them, especially if the amp is driven to a point of overload, then "clipping" occurs and the amp can in worst case scenario emit DC current to the phone, the coil in all dynamic phones/speakers(tweeters) can not handle DC(burnt a few "tweeters" my self in the "early" years of my HiFi hobby - but we all have to learn by our/(others) mistakes!). 1W can actually power a sensitive speaker to some degree... But, if they are "damaged", they would either "die"(burnt coil), or have a "crackling"(damaged membrane) sound - i am shure that you would hear that. So if they sound OK, you probably got away this time. If they are dead(and without warranty), replacing the driver units is not that hard/expensive to do your self - if you have some "DIY" skills. You may even "improve" their performance by getting "alternative/better" driver units. For advise on the "DIY" part i strongly recomend visiting the "diyAudio" forum - there are some very experienced people there that can "guide" you!

I think i will have a go at the Nob, the tweak potential alone is worth the money! If nothing else - it will keep me "entertained" for a long time, beeing retired with loads of time, lol!

Cheers!/T.

 

[TheBIGKill1998]

Thank's for the reply "TheBIGKill1998"!

If you feed nearly a whooping 1 W into a headphone, that's probably designed to handle about 300mW, you can definitly "burn" them, especially if the amp is driven to a point of overload, then "clipping" occurs and the amp can in worst case scenario emit DC current to the phone, the coil in all dynamic phones/speakers(tweeters) can not handle DC(burnt a few "tweeters" my self in the "early" years of my HiFi hobby - but we all have to learn by our/(others) mistakes!). 1W can actually power a sensitive speaker to some degree... But, if they are "damaged", they would either "die"(burnt coil), or have a "crackling"(damaged membrane) sound - i am shure that you would hear that. So if they sound OK, you probably got away this time. If they are dead(and without warranty), replacing the driver units is not that hard/expensive to do your self - if you have some "DIY" skills. You may even "improve" their performance by getting "alternative/better" driver units. For advise on the "DIY" part i strongly recomend visiting the "diyAudio" forum - there are some very experienced people there that can "guide" you!

I think i will have a go at the Nob, the tweak potential alone is worth the money! If nothing else - it will keep me "entertained" for a long time, beeing retired with loads of time, lol!

Cheers!/T.

Hello,

first of all, thank you for your answer on my question!

My headphones dont have any crackling noises from what i can hear so far.
They still (to me) sound quite good.

and also, thank you for your DIY recommendation. If i should ever kill my headphones, i will take a look at the diy audio forum.

 

[Balder]

You are welcome!

By the way, reading on Amazon what people said after bying the Nob, and there was some 100+ comments. A few had have their, some times very expensive, HP's "killed" by the Nob? Reason being was that for some "unknown" reason the Nob had suddenly started emiting loud "hi pitch" noise, apperantly while playing? One guy had two HP's killed, one witch cost $200+!
But the wast majority of those who bought the Nob, and had HP's > 250 ohm's, was extremely pleased with it!

I am getting "cold feet". I have decided to go either OP-Amp "finished product": Douk "BlueBird 5.0" class A mini desktop HP-Amp(OP NE5534x2) = $50, Alternative: SMSL sAp8 = $60 (special offer!). Or go "easy-DIY" and buy: "soldered, finnished, tested-OK", board, discret class A "MOS-FET" + a transformer to feed it (AC 2x18V) = total ca $45, without casing. Witch falls within my budget (exept the sAp8 - need some serius "negotiation" with the wife for that, lol!).

That since i don't really need the "huge" power output from the Nob, and the, rare, but serius "wierd" behaivour of the Nob? For "difficult" HP's - Nob have no competition in that price segment! But i think, in my case, 200 - 300mW, into 42 ohm - would suit my need's!

The "Douk BlueBird 5.0" i somewhat of a "wildcard", but you can "roll" the OP's, and tweak it in other ways, where as the SMSL is an "end" product - nothing that i can tweak(judging from pics of the inside!). Well - I am placing the order on "a" HP-Amp at the end of July, so who know's what other gadget's i'l find?

I am somewhat "obsessed" by getting maximum "bang/buck"!


Cheer's/T.

 

[DavidK35]

Well I have had this amp for 14months now, and I have the same opinion of it now as I did when I first got it.
This is the best amplifier bargain of all time. I run this thing everyday for an average of 5 hours a day & it performs faultlessly. Sound is so good it runs my main headamp a close 2nd.

Some notes:

1) I have 3 headphones all around 50-55 impedance, all work perfectly well (see profile).
No issues whatsoever

2) I use the NOS 6688A tubes (recommended). 10,000 hrs rated & still going strong.
Life of tubes is not an issue

3) I use this adaptor for the Sennheisers (cost less than $4). No issues.



4) It does make a loud thump when you turn it on. Have your headphones off & volume at zero
and it will not be an issue

5) I use a regulated power supply, cost $15 fwiw.
No issues.



6) Amp runs very warm not hot.
Heat is not an issue.

I say again this is the best bargain out there IMO.

 

[MisterMudd]

Well I have had this amp for 14months now, and I have the same opinion of it now as I did when I first got it.
This is the best amplifier bargain of all time. I run this thing everyday for an average of 5 hours a day & it performs faultlessly. Sound is so good it runs my main headamp a close 2nd.

Some notes:

1) I have 3 headphones all around 50-55 impedance, all work perfectly well (see profile).
No issues whatsoever

2) I use the NOS 6688A tubes (recommended). 10,000 hrs rated & still going strong.
Life of tubes is not an issue

3) I use this adaptor for the Sennheisers (cost less than $4). No issues.



4) It does make a loud thump when you turn it on. Have your headphones off & volume at zero
and it will not be an issue

5) I use a regulated power supply, cost $15 fwiw.
No issues.



6) Amp runs very warm not hot.
Heat is not an issue.

I say again this is the best bargain out there IMO.

Everything you say nails it! The little amp opens up every headphone I plug in, and it's awesome.