[svyr]

Definitely a grounding issue.

either grounding or DC on line out? (that said for the later, can't remember whether there are caps in the signal path for 252)

 

[realmassy]

Thanks for your replies guys.
I'm actually using USB from a desktop, through an isolator though. The DAC is connected using an Halide Bridge.
But I tried unplugging everything, and plug the energizer, without source, in a different room; hum still there. I also put it on the carpet to avoid any vibration, but that's not the cause.
I wrote to the ebay seller, and he replied in a few hours, good service by the way: he suggested to earth the chassis wiring it to some metal, and try a cheater plug.
I'll try both today and keep you posted.
 
Talking of the sound, man...so different! I can't believe this cheap system can sound this good.
I listen only to a few recordings (Handel's Water Music by Savall, Haydn's Cello Concertos by Queyras and Bach's Ascension Oratorio by Suzuki): the thing I've noticed immediately is the 'politeness' of the bass. Tubas for example are so clear, and so the brasses in general.
Stage seems sightly narrower, but "forward", out of my head. Less separation right/left channel, which is something I don't like on the Beyer for example.
 
The overall presentation is bright, light, but in a way that is different from the K701 for example. There's no emphasis on the higher frequencies, actually they are smother and less forward than with the HD650. Effortless and natural is the word that comes in mind.
 

 

[livewire]

Did you buy your system new or used?
If used, I wonder if the previous user was dumping his problems?
 
A few other things to try,
Try using it in another building / house.
A little more work - buy a 12V adapter plug / cable at an electronics store and hook it to a car battery.
If you still have noise in both channels without a source, it most likey in the amp.
Keep in mind the plug's polarity. Stax is in reverse compared to most USA branded wall warts.

 

[realmassy]

The system is used, but bought from a authorized Stax seller, and comes with a year of warranty. So replacing or fixing it should not be a problem...just a pain
The adapter is a genuine one, and there's no way, as far as I know, to reverse the polarity with a UK plug.
The house I'm living is 2 years old, and I doubt the problem could lie there...and unfortunately I have no idea on how to hook the amp to a car battery..and I don't have a car anyway!
I'll see if I can fix the problem the way the seller told me, or I'll send it back for a refund.

 

[milosz]

Quote:

I am in the process of purchasing a Lambda normal and a SRD7B on Audiogon. The seller states that the diagram was replaced with 2.5 u Mylar. Any idea of how that changes the sound. He did say it was professionally done.
 

Likely to impact the high frequency response, roll off the highs some I would guess.  Also, the added mass will have some impact on bass response, but I can't quite predict what effect. The extra mass would tend to move the resonance downward, but the thicker diaphragm will be slightly stiffer, moving the low frequency resonance higher.... 
 
Stax now uses 1.35 µ  mylar for diaphragms; for a long time they used 1.5 µ.  Early Stax have 2 µ diaphragms.  Stax Lambda Signature have the thinnest diaphragms at 1 µ.

 

[milosz]

Quote:

So, I spent some time with my new 2050 system, and I'm happy to report I like what I heard.
Definitely different from my previous Woo 3 + HD650. I'll listen to a few more albums and then post my impressions...but so far so good!
 
But, I've got a small issue with the SRM 252: there's a hum coming from it and transferred to the headphones. It's not loud, but noticeable.
The hum disappears touching the chassis with my hand.
I've unplugged the source, but the hum is still there...any idea?
 
Thanks

Is it a HUMMMMMM  or a BUZZZZZZZ?
 
HUM  is sometimes MAGNETICALLY induced into the amp or Dac, you'll need to physically move them to see if some quieter location can be found.  Hum as in something close to a pure 60 Hz tone (50 Hz in Europe / UK) with maybe 120 hz and 240 Hz harmonics but not much above that.
 
BUZZZZZ as in not much 60 cycle fundamental but lots of 3000 Hz, 6000 Hz, 12000 Hz and up- this is typically capacitively induced, like a ground loop as mentioned below.
 
If you touch it and it goes away, this is some kind of grounding issue or a ground loop.  My guess is you have two components Amp / dac  or maybe computer / dac  etc)  that are plugged into different power strips, or possibly into different wall outlets.  Ground (third pin) potential can differ from wall socket to socket, and there is generally some difference in ground potential as seen on the ground (third pin) of various power strips.
 
Lifting the ground (using a 2-prong to 3-pin AC plug 'cheater') can sometimes eliminate ground loop hum, but can be dangerous-  that third pin is there for a reason, you want the juice to flow to ground through a ground wire and not through the user if ever the transformer primary shorts to the case or something.  It's best to keep third pins in use.
 
Best practice: plug everything that is physically connected to the headphone amp into the same power strip / extension strip.  You can always run a ground wire from some chassis screw on one component to a chassis screw on another component.  Any thin wire will be fine.  Just take a length of wire and strip both ends. Touch one end to the metal chassis of one component (amp, dac, etc) and touch the other end to the metal chassis of another component in your audio chain, while listening to the 'phones at a decent level but with NO MUSIC- just listening to the background noise.  Note what happens when you connect the two chassis together. Less hum/buzz?  More?  Experiment with this.
 
 

 

[realmassy]

Thanks Milosz, much appreciated.
You're right, it's more like a buzzzz. 
PC is plugged in one PS Audio Duet, DAC and amp in another Duet. Never had issues with them in the last 2 years (and I tried many sources and amps)
The weird thing is I tried plugging the amp in a different room 10m far from the dac and pc, and the noise was there.
 
I'll also try to replace the PSU, I should have a 12V 1.5A somewhere, that should be OK.

 

[deadlylover]

Watch the polarity on the new DC plugpack. It should be center pin negative, I'd double check just in case.

 

[realmassy]

Quote:

Watch the polarity on the new DC plugpack. It should be center pin negative, I'd double check just in case.

That's a good point deadlylover.
Any easy way to check it? There's a picture on the PSU with some + and -, but I'm no expert..sorry
 
EDIT: forget about it: just seen how to reverse the polarity in the pin!

 

[svyr]

Watch the polarity on the new DC plugpack. It should be center pin negative, I'd double check just in case.

if he got the polarity wrong it wouldn't buzz it wouldn't turn on (i tried that at some point by accident lol)

edit: ops I should learn to read .... nevermind.

 

[treal512]

Hey folks. I've been out of the game for a little while (4 months) and was wondering how I could improve my current setup if I had some extra money to put into it. As it stands now, it is...
 
A PC with 320/FLAC connected via NuForce Impulse USB cable to > a Audinst HUD-MX1 connected via Silver Sonic BL-1 RCAs to > a Yaqin SD-CD3 (w/ Sylvania 6SN7GT VT-231 tubes) connected via Silver Sonic BL-1 RCAs to > a STAX SRM-313 with IeGO's L70530 power cable to > STAX SR-303 earphones
 
(Source > DAC > Amp > Phones)
 
What do you think? I do enjoy it the way it is, but have some extra money and had my eye on stepping up the DAC (Edit: or maybe the earphones to SR-404) to something a little better if it's worthwhile. I'm open to all suggestions/input for improvement.

 

[realmassy]

I tried a few tricks (cheater plug, ground isolator between the amp and the dac, wire the chassis to the rack), but the buzz is still there.
It's on the left channel only by the way. If I wire the chassis to the rack I can stop the hum touching the bold in the rack with my hand.
 
I tried again in a different room, with no result.

 

[spacemanspliff]

Quote:

Likely to impact the high frequency response, roll off the highs some I would guess.  Also, the added mass will have some impact on bass response, but I can't quite predict what effect. The extra mass would tend to move the resonance downward, but the thicker diaphragm will be slightly stiffer, moving the low frequency resonance higher.... 
 
Stax now uses 1.35 µ  mylar for diaphragms; for a long time they used 1.5 µ.  Early Stax have 2 µ diaphragms.  Stax Lambda Signature have the thinnest diaphragms at 1 µ.

I thought that too. Basically, more bass and less speed and extension. A muddy stax? lol
 
We'll see. I can't complain for the price. Still going to be a great headphone for $100 lol.
 

 

[hjt1130]

Anyone know about the stax 717 XLR plug polarity? Are they fit to US standard?

 

[svyr]

I tried a few tricks (cheater plug, ground isolator between the amp and the dac, wire the chassis to the rack), but the buzz is still there.
It's on the left channel only by the way. If I wire the chassis to the rack I can stop the hum touching the bold in the rack with my hand.
 
I tried again in a different room, with no result.

have you tried a different source (hp out with 3.5mm to 2rca even)?