High Frequency Distortion

Bass_Pedal

I recently purchased a Musical Fidelity A3cr preamp, a few days later I got a good deal on a second hand Raysonic CD128. After settling in for a few days, I started noticing a disturbing problem, higher frequency sounds like female vocals, organs, guitars etc, were starting to come through with a slight amount of distortion. It reminded me of the effect that results when you listen to a low bit rate MP3, not as extreme but in the same vein. I found that it is not as audible on some CDs as it is on others. I began to try to narrow down the issue, I tried playing the same CDs on my Oppo player and got the same distortion. That meant it didn't appear to be the new player or the CD input in the preamp as I have the Oppo connected via the SACD input. I then tested out some LPs and found that no matter what I played there was none of the distortion that I had heard listening to CDs. I even tried playing the same albums on both CD and LP and found that the distortion was present on the CD but not the LP. I have the TT connected to the preamp via the Aux1 input as it's going through an external phono preamp. I then tested the TT using all the other line level inputs with the same result, no distortion. After all this, it seems like the preamp is over-amplifying the line level signals coming from certain CDs. I wondering if anyone has every experienced this sort of problem and if this sounds like something that would need professional service to fix.

Thanks

F1nut

Does the distortion come thru both channels? Have you tried different IC's?

Bass_Pedal

It does come through both channels and I tried different IC's between the pre and power amp as well on the CD player to the preamp and got the same result. I even got a little crazy and picked up a power conditioner from Best Buy (30 money back return!) to see if it had anything to do with the AC, no difference.

F1nut

In that case, it would seem as though your pre has an issue. Time for a trip to the repair shop.

Bass_Pedal

I was afraid of that. Thanks for the help. I guess these are the pitfalls of buying used equipment.

steveinaz

Maybe try a different input on the A3CR?

sucks2beme

I had an issue like this. The recording was hot, and the particular CDP had
a higher output than most. A Rotel pre mixed with that CDP had some
harsh sounds on, you guessed it, female vocals. I dumped the Rotel preamp
because of it, and later with my Parasound had the same problem. That
pre had a little red input overload light blinking when I heard the problem.
That pre had a input gain adjustment that fixed it! My other CDP didn't
have the problem. The cd was Nora Jones. There's a couple of cuts from that
album that push it a bit. Amy Winehouse is recorded so hot that the whole
thing sounds like crap.

Bass_Pedal

I'm looking at in-line attenuators right now. I guy is sending me a set of Harrison Labs attenuators for free so I'll see how it effects the issue. I was also looking at Rothwell attenuators. I’m glad to hear that I'm not the only one experiencing this problem. I'll let you guys know what happens after I try them out.

Oh yes, I did try all the inputs on the pre and got the same result, except phono of course.

Bass_Pedal

So today I received a pair of Harrison Labs attenuators in the mail. Since the I was getting them for free from someone I didn't know I didn't think it was cool to ask him what kind they were, beggars can't be choosers! So as I opened the package I wasn't sure which ones I would get... the 3db version... hey it's better than nothing! So I tried them out. Guess what? All my distortion problems, thus far are gone. I tried all the test discs I had played before and all but the new U2 album (which appears to have been mastered for a full on dance party!!) are clean and distortion free! So now that I have confirmed that the issue is gain coming in from the CD player, does anyone have any suggestions as to a better attenuator or are there other possible solutions. I am particularly worried about effecting sound quality.

Thanks

adam2434

I’ve experienced clipping/distortion from the analog output from a DAC in the past, with very hot recordings. Interestingly, certain tracks on Norah Jones Feels Like Home is one of them. The clipping sounds like fuzziness and hardness in some of the vocals.

This is not the same as having a gain issue with the preamp though. The preamp issue may be more related to overloading the preamp with the combination of a high output source playing a hot recording (voltage too high). However, it is interesting that both of your CD players produced the same result. What preamp were you using before, and do you still have it for experimentation?

Although the source and preamp equipment should be able to handle the output voltage of any CD track, these damn super-hot recordings are definitely part of the problem, IMO.

Bass_Pedal

I thought it was odd that both players caused an issue as well. I hadn't tested my previous preamp until yesterday. I was using a MF A3.2cr before I got the MF A3cr that I'm using now (I prefer the more laid back sound of the A3) When testing the A3.2, I didn't get any of the distortion problems. While I'm happy that the attenuators solved most of the problem, I do find it odd that it is an issue in the first place. My preamp may need to be serviced, but I really don't know what kind of cost that might incur and I’m a little afraid to find out.