Diagnosing Weak Channel Problems

[xxJPMxx]

One caveat. This unit is very quiet as a line stage, but very noisy with phone using a LOMC. It also has a "whooshing" sound every few minutes which can often be heard over the music. So I'm wondering if there is any way to quiet this down further and would using a scope be the way to track down noise, and if so, how do I do that.

 

Are you using a separate phono pre? Or are you just plugging the turntable into the normal input? The Marantz 8B doesn't have a phono input so it doesn't have the proper gain or RIAA equalization for records. There are also "test" inputs that bypass the high pass filter, the high pass filter cuts out any low frequency disturbances which is the "whooshing" noise you might be hearing. 

 

So if you are plugging the turntable directly into that amp then that's the problem.

 

Glad the other issue resolved itself. If I were you I would still wiggle and or resolder all the connections that were previously worked on.

[thebes]

Yes I am using an Anthem Pre1 which has switchable gain settings for high and lo gain loading for the cartridge, (I 'm using a LOMC) plus resistance and capacitance loading.  I'm also using the "Test" input on the amp and  always have cause I was told to by wiser heads than I.  But you've put an idea into my poindexter.  I think I'll try the regular input and see if there's any difference.  Maybe I screwed up somehow.

 

Naw. 

 

Impossible.  . 

 

Couldn't happen.

 

More than likely

[babadono]

Just be careful. I was told on another thread just the other day that a part cannot partially fail and there is no such thing as something being intermittent.

[xxJPMxx]

I'm also using the "Test" input on the amp and always have cause I was told to by wiser heads than I

 

Test inputs are probably fine with CD players, DAC's, and other sources but not a good idea with records, low frequency artifacts from tonearm resonances will cause woofer flapping. When using the Anthem phono preamp use the normal inputs to shunt anything under 20Hz.

Edited October 26, 2015 by xxJPMxx

[thebes]

Sorry about the confusion.  The "test" input jacks are on the back of the 8b, and even Saul Marantz told people to use them over the regular input. Can't remember the reason, but its the way to go with those units.

 

I did try the regular input after my post and it was much noisier.  I think what I really have to do is lower the gain a bit on the high side for the Anthem Pre1.