I've had my ma6100 for four years (it's my second one -- bought my first ca 1978); it's connected to a pair of tannoy arden speakers (ca 1978). I'm currently running a teac cd player (ca1992) through a musical fidelity tube buffer into tape input one. I've begun to notice a low-volume "hiss" from both speakers when no music/ signal is played. Is this a problem with the 6100 or is this a power conditioning problem? I've had a few other interesting problems with this 6100 during the last three years, but I would like to address the "hiss" first. Can any of you offer any suggestions. Thanks!
My first guess would be a tube starting to go bad. Is this noise heard when nothing is plugged in to the 6100 or just when you are listening through the tape input? When was the last time you did a thorough cleaning of all the connectors on all the units?
I still hear the "hiss" when I unplug the tube buffer, so I think tubes can be ruled out. When I unplug everything but the 6100 and the speakers the "hiss" is still present. I have not tried listening for the "hiss" using other inputs, so I'll do that tonight. The 6100 hasn't been thoroughly cleaned in a while, so I'll be doing that, too. Could the "hiss" be generated from a bad transistor?
It might be caused by a transistor, but more likely a component in front of the transistor is causing the transistor to make the noise. Hiss is not a normal problem of AC line conditions. Though if what you are describing is elevated system noise, it could be due to a change in the condition of the incoming line. Is this common to both channels or just one channel? Do you have any type of surge protection on the system? How loud is the noise? Can you hear it from your listening position or do you have to be close to a speaker?
The "hiss" is low-volume and I only hear it when I am very close to the speakers (before I put a cd into the player and at the end of a cd, not between songs). I have a Monster surge protector (computer grade, I think) for my audio equipment. The "hiss" is present even when I disconnect (and unplug)all devices. This evening I will try a few experiments with all input devices unpluged: 1. plug the 6100 into a wall socket and listen for hiss 2. I'll select other inputs (with nothing connected) than tape 1 and listen 3. I'll connect the speakers to the speaker remote-connection and listen 4. I'll try my headphones (I forgot about those!) and listen Can you recommend any further experiments? Thanks
Has this noise become louder recently or is it a matter of you are just now noticing the noise?
Has anything recently changed in the system or in the electrical network of the house or incoming lines? Any new dimmers or cordless phones? Any new appliances?
The speaker outputs are wired in parallel to one another so unless it is a dirty speaker selector switch there should be no difference between Speaker 1 and Speaker 2 outputs. Phono will most likely have more noise than any other input since it is a gain stage. Line level and tape inputs should be the quietest.
If there has been a disruption in power the surge protector may have been damaged (its way of protecting the equipment). Try another AC line. Do you know if the AC outlets are grounded? And if so are they grounded properly? Have you ever checked them for correct connection? You can purchase a small plug in device from a hardware store for a few dollars that will tell you whether the outlet is wired properly.
And this is what I did: I tested all input sources along with speaker sources and headphones; I switched surge protectors (my 6100 cord was not long enough to reach the wall without moving most of the system). The "hiss" appeared everywhere (except on Tape HD which emitted a low-level hummmm. Then I went into some notes on the 6100 that I had collected from this forum in the past four months or so and guess what I found? A thread exchange that included you, gig, Rick Barnes and Gregory Stern (16/4/04). Here's the passage that I found interesting and applicable: "set the volume control at 9 or 10 oclock; now with your ear at the tweeter you should hear a hissing noise that is just random noise from the circuts. Put a good surge protector with RFI and EMI filtering in the system and repeat this. You should hear a drop in the general noise as the crud is removed from the AC line." Bingo! The 9-10 oclock volume position is where/ when the "hiss" is audible. If, as I suspect, the "hiss" source has been identified, do you still recommend the Panamax (as you did in that thread to Gig), or are there other units I should also consider? By the way, I also review some other threads on the 6100 that I had saved and your name appears often. Your knowledge and advice regarding the 6100 is most impressive.
I have sold and owned Mac for a long time; the stores always had service departments as all Mac dealers were required at one time. From what you posted above, I'm going to assume you believe the noise can be identified as just random system noise. If you have to be relatively close to the speaker to hear the noise, it is nothing out of the ordinary unless it suddenly increases in volume. Transistors however generally do not hiss; they sputter and crackle but hiss is normally the province of tubes. A 60Hz hum is almost always a ground problem and in an amplifier the age of the 6100 can often mean power supply filter caps going out. A slightly higher frequency noise would be a buzz and is most often a resistor or didode that has drifted enough off spec to change the way the circuit operates.
System noise can be elevated by the efficiency of the speakers. I sold Mac with McIntosh speakers that were at 84dB with 1 watt in and you never heard the noise. When the same amp is mated with a Klipschorn at 104dB with 1 watt the noise is ever present because the speaker is, in a sense, too efficienct.
If what you are hearing is just system noise, I would try the PanaMax unit. Explain the situation to the retailer and they should allow a return if the product doesn't solve the problem. There are a few products that claim as good performance as the PanaMax but the PanaMax has proven its worth in the area of lightning strike protection here in Dallas. The new PS Audio units offer superior AC filtering but at a substantially higher cost. Good Luck.