Rotel RA-02 + Sennheiser HD 600, pls help...
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panzy001

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Hi to All,

I' ve just bought a new Rotel RA-02. Though the amp is great I' am very disappointed in the headphones output.

The main problem is that the output is very noisy. There is a _c o n s t a n t_ white noise like noise, which is independent of the position of the volume control potmeter. Because the HD 600 is sensititive, the normal listening sound level is almost the starting position of the volume potmeter. In this state the noise / signal ratio is _very_ bad.

What to do?

I suppose, if the HD-600 would less sensitive this constant level noise would be much more quiet, and the normal listening sound level would be the 9 or 10 o clock position on the volume potmeter. In this case the noise / signal level sould be better... But this is not the case...

Any suggestions? Pls do not recommend me to buy a headphone amp, I 've just bought my new amplifier... :frowning2:.

Is it possible to use the Rotel's preamp out for my headphone?The spec. write that Rotel's preamp out is 1V / 470 ohm. The Sennheiser is 300 ohm. I am not an expert in this impedance thing.

Is it bad for the Rotel?
Or is it degrade the sound quality?

Someone at the rec.audio.high-end newsgroup suggested to put resistors to the headphones out. Unfortunatelly I know nothing about this, what kind of resistors should I use, impedance, and type and brand... ?

thx for everybody who spend her/his time to read this message, and
thing about a solution.
 
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pbirkett

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I couldnt tell you if you can use the pre-out, you might be able to knock together an adapter to use the second speaker outputs for the headphones, the amp has a good power supply, so it should be plenty stable.

I've got an RA-01, and I've not heard any noise from the headphone out with any headphones, including the HD580 and the CD3000 which is far more sensitive and revealing of faults than the HD600s.
 
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panzy001

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Hi, thx for answer.

What kind of adapter do you mean?

panzy
 
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lini

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panzy: Are you sure everything is alright with your setup, especially the new amp? What source(s) have you connected to it?

In case nothing's (too) wrong with your equipment, you could indeed try a power resistor or transforming adaptor on the speaker outputs to connect your headphone. Cheaper to buy (and also very easy to diy) and maybe another possible solution could be a voltage devider adaptor between the source and your amp - that would enable you to listen at a higher position of the volume dial and might cure possible output voltage mismatch as well...

Greetings from Hannover!

Manfred / lini
 
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pbirkett

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Somebody on here did a design for a DIY one. Perhaps do a search for "speaker adapter". Then you can use the speaker A/B switch on the Rotel to switch between em.
 
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nilanjan

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Since the amp is new, why don't you take it back? The consensus is that the Senn HD600 is not especially prone to hiss, so the headphone jack probably needs to be checked out.
 
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GWN

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My experience with the RA-02 is that the headphone output is quiet. I've heard it with HD-600 and RS-1's. Are you sure it's the amp that is noisy. Turn off the power on your source and plug your headphones into the amp. If the noise is still there it's your amp, if the noise goes away then your source is to blame. If the noise is generated by the amp return it under warranty.
 
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panzy001

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Hi, an many thx for your answers.

lini and GWN asked me about the source. As I wrote the noise is independent of the volume level potmeter, so I supposed the noise is not in the "input" signal, because the amplifier not amplifies it. Anyway, I switched to an empty input (tuner) and the noise remained exactly the same.

Maybe my description was not exact enough about the kind and level of the noise I hear:

It is similar to the tape noise we can hear on 65-70s recordings and using normal volume level the signal hides it. But at the silent parts of recording it can be heared clearly. More disturbing, if I try to use a quiter level than normal, the noise becomes disturbing, because it has constant level.

Is it normal?

My previous amplifier was NAD 3020B, though ROTEL sounds a class better now for me, but NAD's headphone output had not noise at all!

Other:

I checked it with my AKG K-301. The noise type is just the same, but much more quiet (approx. half), but clearly hearable. I think this difference comes from the sensitivity difference if HD600 and K-301. To achive the same level I can use higher amplifier volume position for K-301.

Other:

No audiable noise comes from the speakers.

There is an error in amp?
 
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daycart1

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I think there is probably a problem with the amp. But try this: Turn your source ON before you turn the amp on.
I've found that sometimes one of my amps is unhappy if I turn it on first.
 
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pbirkett

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Quote:

Originally posted by panzy001
There is an error in amp?


Its certainly possible, as I say, I get no noise from my RA-01, and that amp is identical to yours in every way except is lacks a remote control, and the remote circuitry that goes with it - unless of course, its the remote circuitry that causes it, but I'd like to think for the extra price of the 02 it should not do that IMO.
 
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