[KillingTime]

Hi,

Bought a Creek OBH-21 standard version to run with some headphones.

I've tried this amp with the following:

Sony MDRV150
Beyer DT880

And after about the 2 o'clock position on the volume control the audio starts to clip.

I should note that I'm lifting the bass on the program material by about 10dB.

I've run this setup with my Rotel RA02 amp and the headphones socket on that does not clip no matter how hard I drive it. The only thing I've changed is the amp - and it now clips.

I've tried both headphones sockets on the amp - same result. The 880's clip less (250ohm) than the sony 150's (32ohm), but should there be any clipping at all?

I've also noticed that if I remove the bass lift, I can get further round the dial before the clipping starts again.

I've not read about any of this in the reviews for this amp. Surely it can't be normal.

I did read the spec for this amp before I bought it, and was puzzled about the unusually low output power: 10 mW into 30 to 300 ohm loads. I'm wondering at the moment if the output rating might have something to do with it.

Anyone have the same problem?

Thanks.

 

[HiFlight]

While 10mw will drive many headphones to a very loud level, once you are trying to amplify a very high input signal such as boosted bass, you will easily exceed the output capability of the the amp with the very result that you are describing.

The 2 choices that you have with the Creek are to lower the input signal or use more easily driven phones.

Your Rotel is capable of delivering much higher voltage and current when input peaks dictate, thus it doesn't clip. Its output power to the phones is only limited by the dropping resistors upstream from your headphone jack.

 

[KillingTime]

Fair enough.

I tried turning the input level down, it doesn't really change the distortion because it just happens further round the dial, at the same volume level.

If it can't drive the DT880's to a loud level then there's a design problem (these aren’t cheap, and the Sony's are standard Argos fayre, they type that your average Jo will buy) This is not a valve amp that has a high output impedance.

The WhatHiFi review (just one of many) stated:

drives one or two sets of headphones to satisfying levels....

Which I now see is roughly translated to (reading between the lines):

will distort when you turn it up

I know all amps will begin to distort then you crank them, at this price, for me, the volume level that distortion sets in is just too low.

My Rotel RA02 cost 350 quid, and you can bet they didn't spend most of that money on the headphone section (being an integrated power amp) - that's got no problems.

My JVC mini HiFi system (costing 350 quid in total) had no problems at high volume levels.

At 190 quid for the headphone amp, I thought I'd be getting an even better solution. My Zen Vision M mp3 player goes louder than this without distorting for heavens sake using the same headphones.

It's a shame; I'm beginning to see just how much bias there is in the HiFi industry when it comes to reviewing headphone amps. I hope anyone looking to purchase one of these amps sees this post first, because in all of the reviews I read on the internet, not one mentioned the distortion being a feature (I did wonder if the amp was broken to begin with).

Anyway, I'm off to a studio in Manchester that's going to demo some rack headphone amps. I'll take my headphones along and see what happens when the music is pushed. I realise that most of the studio stuff doesn't attract much in the way of praise in the popular HiFi press, but from now on, I'm going to let my ears do the judging rather than the commercial HiFi press.

'later.

 

[ph0rk]

Quote:

Originally Posted by KillingTime /img/forum/go_quote.gif I should note that I'm lifting the bass on the program material by about 10dB.

What is the program material, by the way?

Are you driving one headphone at a time, or both, and does it recommend one of the two jacks for higher impedance headphones?

 

[KillingTime]

KoRn, I also demo'd drum & bass (various) & dance music (various).

I tried both headphones in both jacks with no noticeable difference, and then both inserted at the same time, same with regard to distortion. I didn't get the manual with the amp so I don't know what does which, although I am to belive from the reviews that each socket has a different output impedance.

Perhaps this amp is aimed at those who like more moderate volume levels, less of the dance club effect and more of the lower volume classical material.

 

[anadin]

I don't want to be the bearer of doom and gloom but I bet you the problem lies with your headphone amp.

The Creek OBH-21 really does have a mixed bag of reviews, most of them bordering on the negative side of things.

For a few quid more you could of got the far superior Heed Canamp of which I have owned and really loved.

Other headphone amps in that price bracket are the excellent Graham slee Green solo 2008 and the X-CAN v3 all of which I have owned and they all blow the Creek OBH-21 away.

If you can return the Creek OBH-21 then do it and get one of my recommendations.

 

[KillingTime]

I should be able to sell it for what I paid (£110). Not the end of the world.

I'll audition before I buy next time. I should have auditioned the OBH-21 and did ask my local Creek dealers, but none had them in for demo (makes sense now).

Thanks.

 

[ph0rk]

Quote:

Originally Posted by KillingTime /img/forum/go_quote.gif KoRn, I also demo'd drum & bass (various) & dance music (various). I tried both headphones in both jacks with no noticeable difference, and then both inserted at the same time, same with regard to distortion. I didn't get the manual with the amp so I don't know what does which, although I am to belive from the reviews that each socket has a different output impedance. Perhaps this amp is aimed at those who like more moderate volume levels, less of the dance club effect and more of the lower volume classical material.

So you're boosting the low end content by 10 db on already bass-heavy and near-clipping music? Does the distortion happen when you -don't- boost the low end? What is your source (feeding the amp)? Does the source clip without the amp? Do other sources cause clipping?

I'd expect pain before the obh-21 to clip on normal material with a line level input.

 

[KillingTime]

>So you're boosting the low end content by 10 db on already bass-heavy >and near-clipping music?

Yes. but this does not cause a problem for the Rotel or mini HiFi system (preamp in from external source).

>Does the distortion happen when you -don't- boost the low end?

Yes, at higher volumes, just not as much.

>What is your source (feeding the amp)?
Behringer Ultrafex Pro EX-3200

>Does the source clip without the amp?
No. when I use the Rotel amp or the mini system amp the program material sounds fine, using the same source components and headphones.

>Do other sources cause clipping?
Nearly everything I've played at high volume clips. The more bass light the material, the less it clips. At lower volumes the obh-21 sounds fine.

It's not the line level thats causing the problem. I've attenuated this using controls on the source equipment, the volume goes down on the amp with the lowered line input, so I turn the volume control on the amp up to compensate, and the clipping starts again.

I think this is simply a case of the amp running out of steam (so to speak). Whenever I've used low output power amps with my main (speaker) system, the same thing happens.

 

[ounkchicago]

I have previously demoed the Creek OBH-21, and I used to own the Creek OBH-21SE. I've never had a problem with bass clipping or any unusual sonic distortion under normal listening levels with the DT880. I notice that you said you notice distortion when the volume control knob is at 2 o'clock. However, I have found myself unable to reach that volume level without hurting my ears. If my memory serves me correctly, about 11 o'clock was the highest I'd ever go for normal listening, and 12 o'clock was already bordering on long-term hearing loss.

Nevertheless you have a point in that your Rotel doesn't clip when your Creek does. If you plan on playing your music that loud then maybe the OBH-21 isn't the right amp for you. I'd say you need something more powerful.

 

[ounkchicago]

Oh and I should also add that the OBH-21 sounded very unimpressive to me for the money. So even if you didn't have the clipping problem, returning, exchanging, or trading the OBH-21 may be a good idea. I liked the OBH-21SE a lot but it is rather expensive, and I'm convinced that at that pricepoint there is better out there. I ended up trading in my OBH-21SE toward a better source and buying a LD MK IV SE instead.

 

[seroxatmad]

Hi

I built 2 Kumisa III headphone amps off the headwize site.

Now a friend has dropped in his Creek OBH-11. I was suprised to see it was more than a CMOY - it has a NE5532 OP-AMP and BD139/140 output transistors.

It has a very bright forward harsh sound compared to the Kumisa, it does seem to have a bit more treble detail but is to harsh and bright. The 3D bass is also missing. Also the wall mart PSU may prevent it driving my Senn HD580's louder. When I change back to my Kumisa all I can say is it blows it away....

Does anyone know if this is similar to the JLH design? i.e OP-AMP driving BD type output transistors.


John

 

[tinder]

I have Creek OBH21 non se and a Graham Slee Solo MC and while the Solo is the obvious best of the 2, i've never experienced clipping with the Creek and i listen to dub amongst other things on it.