Midrange Increasingly Harsh


Lately I've noticed some harshness in the mid-range, especially with violins, clarinets and female voice.  I recently bought a CD of female plainchant, and she hits the un-sweet spot so frequently I can't listen to it.  I don't listen at high volumes, rarely over nine o'clock on the volume knob.  The sound is not anything unnatural, just a less musical presentation and an unpleasant harshness.

 

I have twenty year old Forest Totems with their original cones, a Prima Luna Dialogue One amp which got new tubes about five years ago and an Arcam CD-73 which got a factory rebuild about three years ago.  I have neither the money nor inclination to just start arbitrarily replacing parts, but would appreciate some insight and guidance on likely culprits. 

Thanks,

John Cotner

New Ulm, MN

jrcotner

OP mentioned the problem persists from BOTH CD and TT, sooo, that rules out source equipment.

It is unlikely both speakers would develop problem(s) at the same time. So, simply switching speaker wires, left to right, right to left, NO OTHER CHANGES: IF the problem moves to the other side, it's that speaker.

Tubes: get paper, make notes, easy to confuse yourself or forget. Swap all tubes L to R, problem move? Next: using tubes from the 'good side', swap l/r one at a time, any single tube swap make a difference?

Many tubes last 10,000 hours, so 5,000 hours is not a DEFINITE answer. Ask seller about the tubes you bought from him, what are the life expectancies of the tube types your unit uses?

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How many times have I advised a simple tube tester to give answers when problems occur????????????????????????? Blindly buying tubes is an expensive shot in the dark.

 

I did some side-by-side testing yesterday and discovered that there is no difference between the left and right speaker.  I swapped cables and no change.  But when I changed from the eight ohm to four ohm output, the harshness decreased somewhat.  My bride couldn't tell the difference.  I got in touch with Upscale Audio and ordered a set of Tung-Sol EL34B power tubes.  We'll see how that goes then get some new 12AX7 and 12AU7 tubes.

 

Handy to have a decent small SS amp around.  :)

If Speakers,

If I remember the Totems used the XT-25 tweeter that is anything but harsh. So I will have to be on the tube guessing camp. Note the range you may be hearing may actually be woofer breakup. Also note, if I got my speakers correct, the Vifa is great above 4K, so that puts quite a strain on the woofer. Anyone who tries to use the Vifa much lower, well it's distortion skyrockets as it just does not have the surface area. 

Now, harshness is an issue. Due to the loudness wars, a lot of newer CDs are quite hot. Doe to how digital filtering works, there is rick of digital clipping in the DAC. This is why I set my JRiver to the default -1 dB and some suggest -3.  It helps on those female vocals, Judy Collins, Joni Mitchel etc.  I have also found differences in DACs to make this more or less sensitive. Some DACs, like the RME have this internally. I do not know if any CD player does. 

I replaced the Mullard  EL-34 tubes with Tung-Sol EL-34B tubes and after some run-in time I replay the Hildegard Von Bingren CD which started this.  The sound is much improved and not nearly as harsh.  The higher register soars rather than screeches.  I don't have back-up 12AX7 or 12AU7 tubes so need to get a set of them as well.  I'll roll them in to see how things change.