[Toby M]

I recently got a Cute Beyond amp to go with my Fubar II and am really enjoying it

. But with some headphones there's an audible background hiss, even with volume on minimum and nothing playing, in particular with my CX300's. I can also hear it on my PX100 but not on my HD555 or any of the cheapo full sized Sonys we have lying around.

I've tried unplugging the amp from the DAC and it's still there. With nothing plugged in other than headphones and the power cable with the amp turned on it's there. With my CX300 the noise from it is louder than from my mp3 player. Changing the gain setting on the amp doesnt seem to make any difference.

Any suggestions for fixing this?

 

[ADD]

Perhaps this is another example of the often-reported problem relating to using sensitive headphones with some amplifiers. I've been very wary of this potential problem since I own Westone UM2s. From my own research there are very few amplifiers that won't produce a low level of hiss with very sensitive IEMs.

 

[Toby M]

I don't really expect perfect silence but none of my mp3 players have this much hiss, even the tiny iriver s10 which is known for it. But they're way less powerful obviously compared to the amp, maybe this explains it.

Firestone tech support tell me it's probably defective so they're replacing it. If the replacement is the same I'll just live with it since I don't use the cx300's on it much anyway.

 

[shigzeo]

yeah, cx300 is a sensitive iem - the um2 is the worst that i have heard - i have no idea what the point of such sensitive phones are - i sold them and got the atrio m5 - now i can enjoy the music without a portable amplifier.

i would reckon that hiss also depends on how attuned your ears are to it. some people did not hear hiss from the cowon d2 - but it is as present as an ipod nano. i probably use every opportunity to preach about this, sorry.

nice pic though. i play table tennis though admitedly after an inujury, i am no longer ranked in ontario as i haven't played more than 20 times this year

 

[ClieOS]

I think this might be cause by CX300, which is known to have a lot of hiss..

 

[ADD]

Hi Toby,

I'd be very interested to hear back from you in relation to whether the replacement unit solves the problem or not. I suspect it wont unless the replacement has different op amps in it. From a different tack, I seem to remember reading a thread here about someone who had incessant hiss (not from a Firestone). They ended up replacing the op amp and the hiss went away. On the plus side, if you had forked out for the far more expensive Little Country, that might have been worse again as regards background noise from what my research here indicates (note this only applies to using sensitive IEMs).

Hi shigzeo,

I agree about the Westones being the worst for hiss, however I love the sound and ruthless accurary so much I am prepared to have that as a trade off. I have an iriver T60 and the Westone is the only headphone I have tried that substantially reveals the noise floor on the unit. That said, the hiss levels have actually gone down a bit as the headphones burn-in, since the sound has become more balanced and it has opened out - therefore it sounds jut as good to me a few dB lower than it did when it was new. I've also got the Sennheiser CX300 phones, and they do not reveal the hiss to the same extent as my Westones (hiss level seems to be about 3 - 4 dB higher with the Westones), though it is still audible with my iriver. Nevertheless, as soon as the music starts (and I listen to classical only, so there are a lot of quiet passages), the hiss is no longer a bother with either phone. Infact the noise floor on a typical digital classical recording is slightly higher than this hiss level.

But it is for this reason I am having second thoughts about getting an amp at all. I feel sure that just about any amp I try would boost the hiss to levels that become annoying. So far I think the battery powered RSA Hornet or Tomahawk are the only amps I know of of where no users here have reported hiss when using sensitive IEMs. Possibly the Grado RA-1 as well, although there was one user I could find who has reported hiss with that too.

The Cute was on my earlier shortlist too, but perhaps not anymore thanks to Toby's post. But it will be interesting to see if it is faulty or not.

 

[Toby M]

Thanks for the replies =)

Shigzeo: Yeah, I dunno what the hell the point of such sensitive IEM's is either. My tiny iriver s10 (serious its the same size as the new ipod shuffle) plays loud enough for me at 12.5% volume.

ClieOS: True but I would still have expected a $200 amp to have less hiss than an mp3 player smaller than a coin using the same headphones

ADD: I've changed the opamps and it did nothing. I tried swapping in both LM4562's and swapping the opamps with those in the Fubar II, nothing made a difference to the hiss. If I were you I'd keep the cute on your shortlist, I'm very happy with it except for this issue, and I'm pretty sure it's at least partially due to a defect. I'll let you know how the CX300's go with it when I get the replacement one.

I really do think this one is defective, it's not like the noise is only there if you really listen for it, it's glaringly obvious even while music is playing. Anyway, the new one should arrive monday so we shall see

 

[ADD]

Well I guess I should keep it on the shortlist. It's nice to know that the seller was readily prepared to swap it out for a replacement.

One thing I have learned in my short time here: If I dismissed every amplifier that someone had had an issue with, then there would be no amplifiers left to consider!

 

[Toby M]

Yeah. I can highly reccommend Firestone Audio, great products, great service.

Silverstone took 3 months to reply to an email asking if their EB-01 was vista compatible, Firestone Audio took less than an hour.

Their products are well built and the staff are very helpful.

Also remember on any web forum you'll get a disproporionately large number of "I have a problem" threads compared to "everything is great" threads. Kinda like Homer Simpson inventing the "everything is okay alarm" =P

 

[infinitemonkey]

Add my name to the "everything is great" list. I have a Fubar II and a Cute Beyond and I'm very happy with them.

 

[ClieOS]

I always like how FireStone do business. I got mine repaired in 3 days, which is the best statement any company can put out there.

 

[Toby M]

Okay, I've received the replacement Cute Beyond and it's better than the first one.

The hiss is still audible with the CX300 (which are the lowest impedence and most sensitive headphones I own, they're very sensitive IEM's), but it's not as loud and isn't really that noticable unless you're listening to classical (or other music with lots of quiet bits) at low volume. With full sized headphones it's completely inaudible at all times. It sounds fantastic with my larger headphones, it's very nicely made, I love it.

Also I'm extremely impressed with Firestone Audio's customer service. Excellent company, highly recommended!

 

[raymund]

I've had a similar "hiss" problem with the Etymotic ER-4S IEMs and the Firestone Audio Cute Beyond, but I think I've found a solution.
 
The Firestone Audio Cute Beyond offers you a choice of two settings for the volume control – series (default) and shunt modes. If you remove the volume knob and open the case of the unplugged amplifier, you will find two small switches beside the volume control. You need two switch them both from the "Series type" to the "Shunt type" setting.
 
Using factory default (series), even without any connected source, there is an audible hiss that increases with higher volume settings. Touching the volume knob induces extra crackling noise. Though there is less noise (hiss) at the "High gain" setting, still it is too much. (Check this when volume knob is turned up to its highest value, but disconnect any source component before you do this, otherwise it can get painfully loud.)
 
* Solution:*
I've changed the volume control setting from series to shunt and the background noise (hiss) is almost completely gone. Touching the volume control knob neither induces as much crackling noise anymore as it used to. The amp sounds much better.