[Punnisher]

I'm using an old Hitachi SR-2000 as my HP amp, and I was wondering if it would be possible to add a ground to this unit to prevent interference from introducing static into the output.

Is this possible, unnecessary, or just plain stupid?
If it can be done, how?

The amp seems very quiet, but there's a bit of hiss noticable when listening to very quiet music.

 

[fortney]

Most of the older amps I have seen have a ground connection point (terminal) somewhere on the back marked as ground. If you have one you could run a wire for several feet and leave it in a reasonable place around your amp table or connect it to a copper cold water pipe.

I never noticed this helped anything.

The hiss could be be a multiplicity of other causes too. If trouble persists plug it into a different electrical output. If no joy then visit Audiokarma. Several members there do work on classical stereos and are happy to share advice with you.

F

 

[bhjazz]

That ground connection might be strictly for a turntable, although I suppose that shouldn't make any difference. Ground is ground...might be worth experimenting, anyway.

 

[Uncle Erik]

You might want to start with removing the old cord and installing an IEC jack there. Might take some drilling and shaping, but I like being able to detach a cord from a piece of gear. You can easily add a longer one if you want.

Once you do that, you can connect the ground lug to the chassis or to the ground in the circuit. You might also want to add a RF filter between the IEC and the power supply. A local electronics store sells them for $3 each, and I always add one to my projects.

 

[JackH]

Quote:

Originally Posted by Punnisher /img/forum/go_quote.gif The amp seems very quiet, but there's a bit of hiss noticable when listening to very quiet music.

You're probably hearing the noise floor of the amp. Do you know how old it is? What you are hearing is quite typical for equipment made prior to the CD era (early '80s). It was quieter than any of the sources playing through it, so you didn't really notice it.

At any rate, I don't think grounding will help at all. It can eliminate (or cause) hum problems, not hissing.

 

[Punnisher]

Well now That you mention it, there is a slight hum (the hum does not increase with volume level). The hiss increases with volume level, but is hardly noticeable at normal listening levels.

I can't find much on it, but it seems 1981-82 was the production year for this model. Even if it's not curable, I don't mind. It sounds great.

Thanks for the replies. I'll try running a new cable with a ground and see what happens.

 

[Punnisher]

I noticed when plugging in my 770s that when I touched the tip of the plug to the stainless faceplate that there was a loud hum, so I decided to recable it. I used a nice shielded power cable and soldered the ground and shielding directly to the chassis. Now there is no hum when the plug is touched to the chassis. Also the low frequency hum when wearing the headphones is gone. Sweet.

 

[fortney]

Excellent!

F