[Nico]

Hi guys!

Well after further readings of Head-Fi and Headwize forums, I decided to invest in a good amp and some good interconnects. I went and ordered the OBH-11SE and Van den Hul D102MKIII ICs.

Today I received both of them and hooked them up. Based on what I read from Headwize, the impedance for output #1 is 68 ohms and the impedance for output #2 is 30 ohms. So I connected my CD3000 to output #2. But to my surprise there's a very audible hiss in the background, which gets louder as I turn up the volume. The #1 output produces hiss too but I can only hear it when I turn the volume all the way up (and the hiss is lower than the #2 output.)

What seems to be the problem? Am I doing something wrong?

Nicolas

 

[anders213]

Nico: Regarding the hissing i dunno. Maybe its the source? Maybe its the CD itself?
Anyway there is no rule to which Output ya hook it up to. It all trial and error. If Jack #1 works for you than why not?
Trust your ears not the specs.

Anders

 

[Nico]

Thanks for your advice! I know what you mean and I can always plug the hp into output #1 and I actually have it set up like that now.

Hiss is a subjective thing and its presence is usually not acknowledged by every single person. But once you hear it, it's difficult to forget about it.

I guess I'm puzzled because I've read some posts on this forum saying that the OBH-11SE is very quiet when used with the CD3000. I understand there are many factors that might cause the hiss but I'm just wondering if there's anything I can do to eliminate it.

BTW, I'm using the following setup:

Sony SCD-C333ES - Van den Hul D102MKIII - OBH-11SE - Sony MDR-CD3000 or Sennheiser HD600.

 

[Tim D]

You would need different source or amp to really know. I have no doubt that the CD3k is probably a hiss hound of a phone that is very revealing of electronic noise as opposed to other headphones like Senns, AKG, Beyer. Grados are probably the only other phone that have low impedance and sensitive enough to reveal hiss, but even the Denon AH950 was a bigger hiss hound of a phone. CD3k with its reputation seems to be quite another electronic hiss hound headphone.

I just know that the OBH-11 (little brother amp) was a very very hiss-free headphone amp so I would look towards swappage of source, and attention to equipment placement, EMI/RFI interference, power supply issues.

And its also true, many recordings have an ambient level of hiss...but this type of noise is present in any revealing headphone and usually is disregarded as part of ambience and just sometimes depending on the recording. Sometimes a good system can make sense of what is commonly thought of as random noise and create a sense of air out of it depending on the recording. You need a null track of zeroes if you really want to figure out any hiss woes.

My system has always had a very high S/N ratio with a variety of sources, amps, headphones, so I don't see any reason why yours wouldn't.

Oh and yes, from what I've heard from the Creek amp...its S/N ratio is ridiculously much better than what is quoted. From what I remember of when headroom had test data, it was near 110. First check the recording, than source, etc going down the chain. IMO removing equipment hiss is important...otherwise one might not ever realize that recording hiss can ever be more than just hiss.

 

[kwkarth]

The CD3000s are very sensitive cans but in either jack, they're very silent in the OBH-11SE with the volume turned all the way down. With a quiet source they're virtually silent even with the volume turned all the way up. So, if you hear hiss when the volume is turned all the way down, you may have a defective amp. The published spec for signal to noise ratio isn't all that spectacular ">60dB" but my unit seems to handily exceed that, although I haven't actually put it on an Audio Precision test rig to see for sure.

 

[dngl]

Could this be dirty power and/or EMI/RFI interference?

 

[kwkarth]

I suppose it's possible that something is being picked up by the cable and detected by the amp. I don't remember how well filtered the output of the OBH-2 is. It has been well over a year since I was inside of mine. Some ferrite donuts at the amp end of the power cord couldn't hurt anything though. The wire used from the PS to the amp is some really cheap light guage zip wire and some day I'm gonna replace it, but in the mean time I make sure I give it a half twist it once an inch over the length of the wire to minimize any RFI. I live in a ground plane from some commercial radio/TV xmitters so I am careful to prevent those sorts of problems.

 

[Nico]

Ok, I tried all the different scenarios with the OBH-11SE and the CD3000 again and the following is what I heard. This is a rather long post so please bear with me.

1) Amp on, CD player on (stopped after playing a CD):

Output #1: very slight and soft hiss. The hiss increases as I turn up the volume.

Output #2: slightly louder hiss that behaves the same way as the one above.

2)Amp on, CD player on (no CD inside)

Output #1: very slight and soft hiss. Does not increase with volume.

Output #2: slightly louder hiss that increases as I turn up the volume.

3) Amp on, CD player off

Exactly like scenario 2)

4) CD player off. Amp is turned on.

Output #1: Right after the amp is turned on, silence. Then after about 5 seconds, a very faint hiss is heard. It does not increase with volume.

Output #2: Right after amp power on, silence. Then after about 5 seconds, a slightly louder hiss is heard and it behaves like the one above.

I have to reiterate that the hiss in both outputs are not as loud as the hiss in old classical recordings (ADD stereo and mono). Also, the hiss is heard predominantly in the left channel.

Finally, 2 questions come to mind. a) How quiet is the SCD-C333ES? and b) How quiet are the VDH D102MKIII ICs?

Thanks for reading and I would be forever grateful for all the comments that you guys might have.

 

[Tim D]

IC's don't generate hiss on their own...wheter or not they may act to attenuate hiss or reject interference is another matter.

I have cheap AR IC's and don't have an issue of hiss on my Grado MS-1 (the only electronic hiss revealing headphone I have since I ditched the Denon-AH950 which was a miniscule 24 ohm phone). Out of the Art D/IO with some attenuation I can max the amp on my power amp and the headphone jack won't reveal any hiss. I do believe my Denon-370 is slightly noisier.

With the volume levels at levels where the music would be extremely loud I can get hiss-free output. I can however still extract hiss from either D/IO or Denon with my speaker output of course and ears pressed up against the tweeters. I think your system should be pretty hiss free at volume levels and situations of which you would normally hear music...wheter or not you hear hiss at volume levels that would be insane is mostly irrelevent.

Even my Marantz Tuner is a very hiss free device (maybe even more so than the default Denon).

My JMT amp has a gain of 5-6 and it is very hiss free. I remembered the same from the Little, again only amplifying noise from the Denon (which is low enough to not make a presence at any reasonable listening level). Keep in mind the TA was slightly hissy by my standards. The Creek OBH-11 was not hissy to me.

Again you can try to rearrange things slightly, clean up connections a bit, and look for any difference. I do admit I'm perplexed about the difference between a CD player with a stopped CD, and a CD player without a CD, but right now it looks like source mostly. IMO, an SACD player should have extremely high S/N ratio if it wants to claim to take advantage of higher-fidelity media.

Course every component may contribute slightly to noise...but again an ideal (for me), is that there shouldn't be audible noise even on a sensitive headphone at any reasonable listening level. However Sony 3K might be hellishly revealing of this, so I cannot say for sure. Try to run the HD600 through these tests. If the HD600 can reveal it, I'd figure it to be more a source issue than amp issue. For example the TA can be hissy depending on what headphone you try on it, but if what you feed it is hissy, than any revealing headphone should also present hiss. Hiss that ramps up as you jack up the volume is more indicative of something before the amp, and hiss that stays the same regardless of volume control is more indicative of something at or after the amp(well obviously there isn't much after but the cord to your headphones). Could be an impedance/efficiency issue as well which is a trend in that high efficiency, low impedance phones are revealing of amp hiss.

 

[anders213]

Nico:
I just tried out both jack with my HD600 + Clou Red. See if its of help.
Amp ON and CDP ON
Jack #1: At low volume up to 3 Oclock, no hiss heard(to my ear) but beyond that the hiss appears and gets louder and louder. But still subtle.
Jack #2: Similar to Jack #1, only that the hiss is that little louder.


Anders

 

[dngl]

The C333ES is dead silent.

 

[teekm]

My guess is that one of the screws holding the plates are not tighten properly, especially the one holding the RCA sockets together. It seems that the some point on the PCB needs to contact the case.

BTW: I realised this after having an inside look at the SE. And for those after an objective eval, this baby is clean as a whistle. Crank up the pot and the distortion goes lower till you hit the limit of a HP8903. It does roll off a bit early at 15kHz. Crosstalk at 15kHz is about 30 odd.

teekm

Quote:

Originally posted by Nico Hi guys! . But to my surprise there's a very audible hiss in the background, which gets louder as I turn up the volume. The #1 output produces hiss too but I can only hear it when I turn the volume all the way up (and the hiss is lower than the #2 output.) What seems to be the problem? Am I doing something wrong? Nicolas

 

[Nico]

Thanks guys for all your comments!

anders213: I think you and I are describing the same hissing noise. The difference is that CD3000 is more revealing than the HD600, therefore the hiss is higher in volume.
So is this subtle hiss a manufacturer's defect or something that one has to live with?

 

[kwkarth]

Nico, It sounds defective to me. You shouldn't hear any hiss. I have CD3000s and the OBH-11SE and it is silent.