Maybe hakaplan or someone else can point me in the right direction to solve this problem. My Dual 606 sounds great when it is playing, but after playing for a while it will get a loud hum in the left channel! I know the problem is not in the receiver, as it has done this on every receiver or amp I have run it on.
I have made sure the grounding wire is securely connected to the receiver. The original needle, an Ortofon Dn 1 55E (which was broken when I got the 606) has been replaced with 4542-DEV from Ed Saunders. It is an Ortofon replacement and says it is the replacement for the DN 1 55E needle on the package.
What's really perplexing is that the hum comes and goes, it's not a constant thing. I have tried all manner of tracking force and anti skating adjustments, but the problem still persists.
I do have the adapter to use a regular type cart on this table. Is this something I should try? Any suggestions would be appreciated! :yes:

When you say it comes and goes, do you mean while playing the same record it will come, then disappear, then reappear? Or do you mean, it shows up on some records and not on others? Does it appear at the same place on the record every time? When it hums, does the hum intensity change if you move your hand near the arm or touch the arm. Does it occur if you simply lift the arm and move it toward the platter?

I suspect there may be a disconnect switch associated with the arm movements? If so, it may have dirty contacts?

When you say it comes and goes, do you mean while playing the same record it will come, then disappear, then reappear? Or do you mean, it shows up on some records and not on others? Does it appear at the same place on the record every time? When it hums, does the hum intensity change if you move your hand near the arm or touch the arm. Does it occur if you simply lift the arm and move it toward the platter?

Howard, it just starts humming randomly while the record is playing. It doesn't happen at the same place and time on each record. Sometimes it will play one side fine, and I can flip the record over and it will play a little bit then start the humming. Sometimes it will start humming on the 1st side. The hum intensity doesn't change when I put my hand near or touch the tone arm. If it is not humming it doesn't start if I lift the arm and move it. It is really aggravating me as it has no pattern to it. I have no problem like this with any other of my TTs.

What kind of RCA cables are you using? Are you located near any type of radio or transmission towers?

Only things that I can think of that weren't mentioned already is a loose wire connection at the cartridge or intermittent broken wire in the RCA cable.

Is it sitting alone or on top of an amplifier?

Boy, that's a really common problem. Dual used cables with crappy end connectors and the symptom that you're describing happens all the time. If you wiggle the cable connector (usually it's the one that goes into the back of the amp) the hum goes away. It will then start gradually building up again and eventually get so loud that it takes over everything - wiggle it and it dies out again. Change the interconnect cables and you'll be fine. I've had the gradual hum syndrome on several of my Duals and lots of other people's Duals over the years and that's all it has ever been.

*EDIT* If the turntable end of the cable is permanently fixed to the turntable and you don't want to open it up and change out the whole cable, just solder new RCA ends on the cable. Do both left and right as this will eventually happen to the other lead end as well.

Boy, that's a really common problem. Dual used cables with crappy end connectors and the symptom that you're describing happens all the time. If you wiggle the cable connector (usually it's the one that goes into the back of the amp) the hum goes away. It will then start gradually building up again and eventually get so loud that it takes over everything - wiggle it and it dies out again. Change he interconnect cables and you'll be fine. I've had the gradual hum syndrome on several of my Duals and lots of other people's Duals over the years and that's all it has ever been.

*EDIT* If the turntable end of the cable is permanently fixed to the turntable and you don't want to open it up and change out the whole cable, just solder new RCA ends on the cable. Do both left and right as this will eventually happen to the other lead end as well.

Thanks for everyone taking the time to respond to my problem.
But I think changing the connecting cables is worth a try. He is describing exactly what this TT is doing. I'll let everyone know if this takes care of the problem.

Does this Dual 606 have the same headshell and contacts as the 1009? If so take out the headshell and thoroughly
clean those contacts and clips. I worked on this same problem for about a month and until I rubbed and scrubbed every visible and invisible place that made contact even the inside of the clips that clip on to the cartridge did I gain success. I used Brass0 to clean them the last time and so far it has been playing about 6 hours a day for the last 4 days without a problem. I changed cables and everything else that was suggested but until I cleaned everything in the headshell and arm that had turned black it would not work but maybe 15 minutes to an hour before it would cut out again. Don't give up

Does this Dual 606 have the same headshell and contacts as the 1009? If so take out the headshell and thoroughly
clean those contacts and clips. I worked on this same problem for about a month and until I rubbed and scrubbed every visible and invisible place that made contact even the inside of the clips that clip on to the cartridge did I gain success. I used Brass0 to clean them the last time and so far it has been playing about 6 hours a day for the last 4 days without a problem. I changed cables and everything else that was suggested but until I cleaned everything in the headshell and arm that had turned black it would not work but maybe 15 minutes to an hour before it would cut out again. Don't give up

Thanks for sharing your experience. If changing the cables doesn't fix the problem, this will be the next step to try.

Boy, that's a really common problem. Dual used cables with crappy end connectors and the symptom that you're describing happens all the time. If you wiggle the cable connector (usually it's the one that goes into the back of the amp) the hum goes away. It will then start gradually building up again and eventually get so loud that it takes over everything - wiggle it and it dies out again. Change the interconnect cables and you'll be fine. I've had the gradual hum syndrome on several of my Duals and lots of other people's Duals over the years and that's all it has ever been.

*EDIT* If the turntable end of the cable is permanently fixed to the turntable and you don't want to open it up and change out the whole cable, just solder new RCA ends on the cable. Do both left and right as this will eventually happen to the other lead end as well.

Amazing! My Dual CS 505-4 had that exact problem. I traced it to a bad RCA plug from the turntable. I replaced both plugs with cheapo plugs and the problem largely went away. I still hear a faint hum when I crank my amp to absurd levels while PHONO is selected (no record playing) but it's inaudible at normal listening levels.

I'd like to replace the entire RCA cable from the turntable but I am afraid to perform open-heart surgery on an otherwise perfectly good device. I read somewhere that the length of the RCA cable is important as far as turntables are concerned. Is that true? If I replace the cable, I'd like to make it a little longer.

I got some 6 feet RCA cables that I use on my Dual 1209. They are of course way to long and do introduce some hum if the volume is cranked loud. I will be getting some more reasonable 3 feet cables soon.

After cleaning all contacts with no record on I can turn my sx-1250 all the way up and it doesnt hum but I can hear probably a little air current and I also have 12foot RCA cables attached plus about 9 foot ground cable. I know it might sound better if I shortened them but it sounds excellent to my old ears.

I'd like to replace the entire RCA cable from the turntable but I am afraid to perform open-heart surgery on an otherwise perfectly good device. I read somewhere that the length of the RCA cable is important as far as turntables are concerned. Is that true? If I replace the cable, I'd like to make it a little longer.
For use with MM carts, excessive cable length adds capacitance which can diminish high end frequencies. This is why built in tt cables were kept short. However nowadays we have low capacitance cables which enable longer runs. With the right cable, six feet is normal and you can even get by with twice that. I'll be doing a cable comparison shortly, but meantime look up threads on Petra cable.

I got some 6 feet RCA cables that I use on my Dual 1209. They are of course way to long and do introduce some hum if the volume is cranked loud. I will be getting some more reasonable 3 feet cables soon.
You don't need shorter cables, just better shielded ones with low capacitance.

Like the guys have suggested, it's most likely either a bad contact at the headshell or the phono plugs at the end of the cable. Either problem is not uncommon on the Duals, over the fifteen years I used my 506-2 I've had to fix both at one time or another. Not too hard to do and worth the effort.

I'd like to replace the entire RCA cable from the turntable but I am afraid to perform open-heart surgery on an otherwise perfectly good device.

Very easy to do if you have basic soldering skills. There is usually a small circuit board inside which connects the tonearm wires to the RCA cable. Just four solder connections and perhaps a ground wire.:thmbsp:

You don't need shorter cables, just better shielded ones with low capacitance.


Thank Howard:thmbsp:

For use with MM carts, excessive cable length adds capacitance which can diminish high end frequencies. This is why built in tt cables were kept short. However nowadays we have low capacitance cables which enable longer runs. With the right cable, six feet is normal and you can even get by with twice that. I'll be doing a cable comparison shortly, but meantime look up threads on Petra cable.

I read that thread with interest. Would you agree that even basic component video cables offer lower capacitance than the average interconnect? I have several sets lying around here that came with expensive data projectors. I'd love to use them if I could.