Hissing sound when Tone Control is turned on

Hi guys,

Thanks for your replies. The hissing tone remained the same level even when the preamp was set at zero volume. No other tone controls or EQ were in the chains. I have tried unplugging each sources one by one made no differences. And i have also tuned down the treble or made no gains from the power amp, the result was the same. But as soon as the tone control button is turned off on the front panel the hissing goes away completely. That was why i was wondering if this is considered normal for Mcintosh preamp’s. Thanks

None of mine, to date.

Regards.

Hi oldhvymec,

May i ask which Mcintosh preamp you are using ? This preamp performs very nicely and i love it. But this is my 1st time using Mcintosh product and i have no friends using some brand so i can compare with. Maybe i bought a slightly defective unit or perhaps it is normal. I have tried to ask Mcintosh technical support by email but not heard back from them yet. I will just wait and see how they reply to me.

Thanks

C11, C20s, C2500, Mx110z, Mx120.  A few.. When they are tuned up and running they are quiet..

Did you buy it new? Did it just start making noise or out of the box. it made noise?

They make music, not noise..:-) This summer 50 years with Mac.. YUP I'm a Mac guy.. I like their older valve gear.. MC225, 240, 275, 30 and 60s. I don't currently own ANY SS Mac Power amps.. Just valve.. I have a Cary V12R I really like with a Mac front end... Just perfect for me.

I use class Ds to do all the bass duty.. Actually I'll be swapping over within a month or so.. See how the weather act.. Class D, for the main monitors in the summer too. Valves are just to hot.. It gets to be 110 + here where I live..

Regards

I bought a 1.5 year old pre-owned C49 preamp from my Mcintosh dealer. So i had no idea about how this preamp functioned when new. That was why i was hoping to get some guides from Mcintosh users first.

After some time-consuming tweaks on settings of preamp and power amp, I was finally able to track down the problem, The hissing sound during idle can no longer be audible if the output gain on my Parasound A21+ power amp is set to appropriate matching level. I had to turn the gain level down to almost minimum to get rid of the hissing when Tone Control is enabled on my Mcintosh C49 preamp (of course turning off the Tone control is another less preferred option). My previous setup was pairing my Parasound A21+ power amp with Parasound P6 preamp and Parasound official recommended the output power gain for both channels to be set to maximum all the times. And the parasound P6 and A21+ combo were working beautifully as well. I guess i should have done this equipment output matching practice before i raised my concern, especially when i pair the Pre & Power amps designed and manufactured by different brands. I am still new to hi-fi world so i learned an important lesson today.

Thank you for your valuable inputs anyway.

Happy Music Listening !