Preamp or Not

Espoverload, I briefly revisited your earlier thread in which I participated. Mihalis sort of mirrors my thoughts here. I though you had solved your noise problem when you used some XLR connectors on your amps? Not so?

One thing that might be helpful would be if you could more specifically describe the 'noise' or 'distortion' that you are hearing, i.e. is it a buzz in the lower frequencies which you clearly hear when you put your ear near(er) the mid range or bass, or a higher frequency constant hiss heard more clearly with your ear near the tweeter. You use the word 'distortion' and that covers way too wide a range of possibility of sounds.

Another thing to consider is I/C and PC dressing. PC's and transformers too close to I/C or other components can cause problems. As (IF) you follow my recommendation include an examination of their condition and their placement so you will know if it is the source of the noise.

If I had your problem this is exactly what I would do. Disconnect everything from your amps (except speakers of course). Disconnect these components PC's from outlets.

Then carefully reassemble, one component at a time and identify exactly when this noise appears. For example, when you connect your preamp first connect it to the amp but don't plug it. Listen. Any noise? No? OK then plug it in. Any noise? Yes? Pull the PC from the wall of conditioner and add a 'cheater plug'. Still have noise. OK disconnect PC and remove 'cheater plug'. Noise goes away - OK you now have identified your problem as a ground loop caused by your pre-amp. If the noise doesn't go away consider that you may beed dealing with the pre-amp(s) noise floor. They all have one - whether you hear it or not depends on speaker efficiency, amp sensitivity and gain issues. Pre-amps with high gain and speakers with high efficiency for example will regularly have noise issues which will be aggravated by speaker input sensitivity. I'm assuming the noise if the result of the pre-amp for this drill, but if you should continue the drill thru the addition of source components to see if any differences occur as they are added.

If after this drill you can't find a source, consider that the problem may be riding on your houses wiring and or other domestic items on the same circuits as your audio stuff.

It will be very helpful to anyone trying to help you if you can present a thorough, detailed, description of exactly what you have, what you have done, and the results of each transaction.

BTW your first drill will be in breaking this long winded exercise down into some easy to absorb pieces. :-)

Newbee, Thanks for the detailed response. I Understood your response to the last thread and that's how I isolated the problem to the preamp. The noise is a high frequency distortion (hiss) only heard in the mid-range and the tweeter at high volume. As I stated in this thread, my pre and source have only SE in/out. So in order to try balanced connection, I have to purchase a new pre and good IC. Again, I am happy with the sound of the system and I don't need to upgrade at this time. However, if that's what it takes to get rid of the noise I'll do it. But different members have different points of view. Some say XLR makes no difference unless you have very long runs and some indicate it makes a big difference. That's why I'd like to try everything else before committing to buy more gear. I'll try your suggestion on disassembling the entire system and tryng to isolate the source of the interference. I do have several PC's, IC's, RGPS transformer in close proximity to each other. Also my amps and preamp are very high gain and speakers are 8 Ohms with 91db sensitivity. I'll try some more thigs as suggested and post the results.

BTW, what is a cheater plug? Thanks for your help.

I forgot to mention that the other day I was hearing a buzz or spit intermitantly on the left speaker and was worried that a tube was going bad or worse one of the amps! After investigating all my connections etc. I found one interconnect was laying directly against a power cord (perpendicularly by the way). This power cord was feeding the preamp and I'll be damned, that was it. Repositioning the interconnect fixed it. When the noise is occuring try taking a wire and touching to both the amp and preamp to see if the noise worsens or lowers. Do you have a friend with a different preamp that you could see if this goes away?

Espoverload
Sorry I just reread that you have tried new amps etc. Forgive me for being dense. If you know some one with a power conditioner that may be an easy test. Also several years ago I noticed my lights in my house dimming at erratic intervals. This kept happening and it worried me so I had the electric company take a look at my power. On the outside of your house is a a meter. It is fed on three legs. Each leg must read equal voltage. Mine did not. Upon investigation the power company tech said one of the leads was loose at the box in the back yard. This box fed 2 or 3 houses. It is sounding like you have a power problem in your house. Some fluke meters (voltmeters) have ocilliscope screens so you can take a sample of the power at your outlet and see if there is some large scale noise in your ac supply. Good luck!

Espoverload, A cheater plug is a plug with the old fashion 2 blade connector with the big round ground blade removed. You plug your 3 blade PC into it then you plug it into you outlet.

While it is always nice to have one in the drawer to use if you think you might have a ground loop, or where it is, I doubt that is your problem based on the sound you are describing.