Slimx and cmoy trouble

[was ist los?]

Why is it that when i plug in my cmoy into my slimx's line out that i hear a pretty loud hiss, but on the radio, there is no hiss what so ever. The amp alone is not the cause of the hiss because it is dead silent alone. I have tried it in my brother's panasonic cd player and it has considerably less hiss, though still noticeable. I have yet to try the amp on my dad's sony sacd player.

 

[was ist los?]

ok now my amp works with no hiss with my slimx and sennheiser mx500s, but there still is an audible hiss with my grado sr60s.

 

[faehntim]

Did you ever get this resolved? I am building a cmoy variant and I am getting some hiss with my Grado Sr-80's as well. I haven't been able to test it from many sources yet, but computer and pcdp headphone out emit hiss. There isn't any hiss when it's on but not plugged into source. What is this? recording, bad source, interference, bad cable?

Incidentally, I have R5 at 100 Ohms and the default gain (11, I guess).

Also, I don't have any high impedance headphones, so I can't test with those.

I'm thinking it's probably a source problem. I haven't tried my stereo head out or computer line out.

 

[was ist los?]

As a matter of fact, it was my amp was set at too high a gain (it amplified hiss). I found that 3-6 was suitable with grados.

 

[faehntim]

That's what I'm going to have to do. I'm getting too much hiss through the grados even with R5 = 100 Ohm. Thanks, Was ist los. Bist du Deutscher? Ich kann Deutsch nicht so gut.

 

[was ist los?]

Nein, ich komme aus den U.S.A. I take German at school.

 

[Tomo]

Hey,

When I built my very first CMOY amp. I had hiss problem with SR60. The hiss was annoying even at gain of two.

My problem solved itself when I rebuilt it. While doing so, I realized for my very first CMOY, R2 was 1Mohm not 100kohm. They look very similar. I added few things such as more expensive caps and hiss went away.

I believe reduce the value of R2 is an effective method of reducing hiss due to input pickup or input grounding problems. This method is not very invasive so you shouldn't get much coloration. However, I would not recommend going below 10kohms since crossover filters and volume controls will be unhappy with you.

Tomo

 

[Tomo]

Hey,

Don't reduce R2 unless you really run out of options. Because sometimes, it could be loose wire or something. (It does happen to me at least.)

Tomo