Just picked up my REF40 today.... Wow!

[jpgr4blu]

Agreed. The Ref 40 is a game changer. A big step from Ref 5.

[PHC1]

Originally Posted by jpgr4blu

Agreed. The Ref 40 is a game changer. A big step from Ref 5.

Yep.

[Juan]

[QUOTE=uncle_dito;

The loudness of the hiss [B]doesn´t increase with volume[/B], and is independent of the sources, even with no source connected, there it is.

It seems that is not the pre. If it were the noise should increase with the volume

Disconnect the pre and the interconnect between the pre and amp and turn on the amp. If you hear the noise is the amp.

If not, connect the IC cable to the amp WITHOUT connecting to the pre. Turn on the amp, if the hiss is there, the cause are the cables working like an antenna. This is why when you connect balanced cables the hiss is gone.

If this is your situation then you have a problem with RFI and you have to reroute the cables or change for balanced IC

[cmalak]

Welcome to AA Juan

[microstrip]

Originally Posted by uncle_dito

Hello all, this is my first post in the forum

I just bought a second hand Audio Research Ref 3. Quite happy except one issue. I can hear hiss (like "shhhhhhh") through the speakers coming from the Pre, from my listening position, which is about 8-9 feet away from the speakers! I know it is normal to hear some hiss if you put your head close to the speakers, but not at this distance. The hiss is coming from both channels, and can be heard from volume setting 1. The loudness of the hiss doesn´t increase with volume, and is independent of the sources, even with no source connected, there it is. It is loud enough to bother me in quiet music passages or when I play soflty at night.

I have done a few tests:

1. try different interconnects. Try balanced or single ended source inputs. Still the same noise from both channels.
2. try different amplifiers. Then I discovered that the noise was coming only when using the Pre Main RCA or single ended Line outs (1 or 2). With the Balanced outputs, the pre was dead silent (ok, except some erratic noise, like "frying", coming from one of the channels, but not the problematic hiss described. I assume this other sporadic noise is from one or a couple of 6H30 going wrong out of the 4). The valves have about 800hrs. As I have a singled ended amplifier (Musical Fidelity A5 CR power amp), I need to get this issue sorted.
3. Try a different 6550C. Still the hiss.
4. Try rotating the 4x 6H30, the noise was still coming from both channels, it did not go to the left or right).

Ok, so what do you think? Before I send it to the official service in another city, I wonder what the issue might be and if I should try something else. I am tempted to buy and replace all valves, but I wonder if the problem might be something else.

Thanks for your comments.

What are the other components of your system? A friend of mine had the same problem just because his amplifier had a very high gain (36dB) , non balanced, and the speakers were very efficient (93dB/W).
The hiss should remain constant at all levels, except 0 that shorts the output - the REF3 mutes a 0 volume - and the tube gain stage is placed after the volume control.

BTW, the REF3 is less noisy in balanced mode as in this mode noise cancels at the input of the amplifier.

[jwhite613]

Juan... Welcome To AA!!!!

[jwhite613]

microstrip... Welcome To AA!!!!

[Dafos]

Microstrip, pls correct me if I'm wrong but try placing your ear to the speaker drivers with the volume control of any current ARC linestage at 0 setting but with a source component playing and you will hear a very faint signal from the source. This means that at 0 setting the ref preamps do not mute the circuit. I believe ARC uses an ic controlled volume control that very slightly amplifies any signal even when it's supposed to be at the fully attenuated position.

[microstrip]

Originally Posted by Dafos

Microstrip, pls correct me if I'm wrong but try placing your ear to the speaker drivers with the volume control of any current ARC linestage at 0 setting but with a source component playing and you will hear a very faint signal from the source. This means that at 0 setting the ref preamps do not mute the circuit. I believe ARC uses an ic controlled volume control that very slightly amplifies any signal even when it's supposed to be at the fully attenuated position.

Dafos,

Just checked with a Fluke resistance meter to confirm - my REF40 shorts the output when the volumes goes to 0.

The REF3 and 5 also did it. This was a nuisance for me when I wanted to use them with a DC coupled balanced solid state amplifier that had a small input DC offset at the XLR input - every time volume reached "0" it produced an immediate loud and disagreeable click, as the input was being shortened, abruptly zeroing the DC offset. I had to be skilled when decreasing volume to avoid reaching "0" ....

Repairing the amplifier was the best solution to solve this problem.

BTW, even when muted, there is a small leakage of signal from the output with some ARC preamplifiers.

[chessman]

microstrip, welcome aboard!