Here is the basic internal wiring for the turntable...My thoughts are that there is some leakage of the signal into the input of the built in PHONO stage...this might be why the interference is there even when the turntable is not powered: The 2x pairs of RCA sockets are shown on the top right with the switch. The other switch turns the auto-arm lift on and off.
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Hi there. Thanks for your reply. The correct method of usage is to have the switch selected to the chosen connection of the output sockets which I have done. However, I might have operated the switch once when I had swapped the method of using the turntable when the turntable was powered.
Hello 968driver, thanks for getting back again. The way you describe how to use it is the exact way I do use it when I use an external phono preamp. As decent as the built in one is, I find my external ones are better sounding although the hum level is louder than the built in amp. From what you say you seem to also own an SL1500C? If so, may I ask you if YOU can hear an interference crackling when you use it with an ext. amp? It is not loud, as said above, about the level of a vinyl record surface noise, so you must turn the gain up on your main amp to be fully sure if it is there or not. I would put on a recording of the noise on this site but I can't attach jpeg files. If you don't get this noise and I would say you shouldn't as I would doubt Technics would have designed a system that caused this noise, noting the SL100C is the same turntable but has only a straight non-amplified output direct from the cartridge. I can then go back to my seller and tell him that he is talking nonsense and demand a repair or new turntable. Many thanks PS: do you hear more hum when using the ext. phono pre-amp?
Hi, You should be connected to the phono out with your cables and the switch must be in the off position. The info you got from the dealer sounds a bit silly because if this was the case then Technics would certainly know of it and add it to the info in the brochure! Mine works great in that position.
Sorry to hear of your 1500c noise issues. I have had mine for about 18 months and have had no issues with noise. I first built a solid state (2134 op amp based) phono preamp and preferred it to the built in one. I am now using a tube based preamp with phono stage and it is also quiet with no noises. I have no hum issues with either DIY preamp setup. Do you have the ground wire connected back to your preamp ground terminal? The only other thing I can suggest is to inspect the headshell wiring to make sue it all seems secure and that the headshell connector contacts are clean and undamaged.
The only issue I had was my fault when I mistakenly reconnected the cables to the wrong point and was running 2 phono preamps in series. IMO Technics could inmprove the labelling of the switches and connectors on the back panel. It is very difficult to see in a typical setup scenario.
The only issue I had was my fault when I mistakenly reconnected the cables to the wrong point and was running 2 phono preamps in series. IMO Technics could inmprove the labelling of the switches and connectors on the back panel. It is very difficult to see in a typical setup scenario.
Hi, I do not own a Technics SL1500C, but a friend of mine bought one last year and connected the phono output to the phono input of his amplifier.
He had a strange hum problem at low volume.
When I switched off the SL 1500C phono preamp, no hum anymore!
Thanks cln.white and Bfpca for your help... As I thought, I did not expect others to have the same problem as I am convinced my one does have a fault. This will give me a strong case against my seller. I just hate it when non-technically minded people start coming out with stupid remarks like the "timing" on old phono amps might "clash" with a direct drive turntable. As regards the other problem with hum. I have tried many variations regarding the earth and the linking wire but just connecting the earth as described creates the lowest hum but it is definitely louder than when using the built in phono stage which I have to say is very quiet relatively. I have checked and measured the direct output for resistance back to the head shell using a head shell without a cartridge and directly onto the loose tails in it...nothing is amiss. As said before by me, the CRAZY thing is that even without the turntable switched on at the mains the noise is still there. I even suspected induced noise from a faulty dimmer switch or such like but I have made sure everything else is switched off too. It is not inherent in the external phono-amps as the noise is identical with 3x different ones and each is quiet when no turntable is connected to. I have even connected the pre-amps to an old Technics turntable and fitted with different cartridges but there is no noise being generated like the new SL-1500 so it must be coming from the SL1500. I will now contact the seller and ask for him to take it back...preferably to change with a new one but it is now over 14 days...wish I had tested this external phono amp usage earlier. I'm now sure it has a fault but cannot say for sure what might be the cause apart from signal path leakage back into the microprocessor or internal phono amp via the rear selector switch or wiring....
I have exactly the same problem. Brand new SL1500C connected to a Cambridge Audio Alva Solo. Switch on back in phono position, no line level cables connected. I hear clicks and pops through my speakers even when the 1500C is unplugged from the mains. I've turned off everything I can in the area with no luck. It seems to be picking up cellular data, I can hear the noise change when force my mobile phone to connect to the internet. However if turn my phone off I still have the clicks and pops. I've tried another phono stage, a Gram Amp 2, which produces the same results. If I remove the phono cables from the back of the Technics the problem stops. So it seems that something in the Deck is picking up radio signals.
I don’t live in an RF rich area but I have never experienced noise like that with my 1500c. If you are using the 1500 with an outboard phono preamp there isn’t much in the deck to pickup radio signals. Maybe a foot of wire from headshell to rca jacks. Do you have the ground wire connected to the Alva? Have you used other tables with the Alva without encountering this issue? Have you tried disconnecting the ground cable from the Technics. Perhaps changing power cords on the 1500c may be worth a try. The stock molded cord could have a bad ground conductor.
Hi and thank you for your suggestions.
After a few more hours of elimination I've figured it out. It's my powerline networking leaking into my hifi setup. I thought I had turned all of this off in initial testing but must have missed one. So it seems that the Technics SL-1500c is very susceptible to mains power noise.
I've found a cheap conditioner laying around that drops the noise to an acceptable level and will research a better replacement. I hope the message helps others with a similar problem in the future.
After a few more hours of elimination I've figured it out. It's my powerline networking leaking into my hifi setup. I thought I had turned all of this off in initial testing but must have missed one. So it seems that the Technics SL-1500c is very susceptible to mains power noise.
I've found a cheap conditioner laying around that drops the noise to an acceptable level and will research a better replacement. I hope the message helps others with a similar problem in the future.
Sorry for being absent for quite a time on this thread and thanks for all your help and suggestions. BUT...Eureka I found what is causing the popping crackling just like "Death9" but completely independently. It was NOT the technics turntable at all!. It was simply the Broadband "Power Adapters (BT Telecom term ) These are left permanently on to transmit the Broad band data around the house from one at the HUB and the other at the TV position. This is left on all the time and the high frequency data thus interferes and is superimposed on the mains AC supply. Some of this signal is transmitted via the turntable power chord or even transmitted directly into the phono stage. Simply by switching of the power adapters stops the interference instantly. I do feel slightly embarrassed as the turntable was sent back saying it had a fault. Obvious the high gain of any phono pre-amp will pick these signals up but thankfully the problem has been solved. Much obliged to everyone and hopefully our discovery will help others.
Congratulations on finding the problem! This sort of issue is very hard to isolate and identify. Perhaps you should take a close look at the power line network to make sure it is installed properly. You might try a better quality line cord on the 1500. I use a heavier DIY built cord. Nothing fancy, just solidly constructed 16 gauge. Those molded cords often have poor connections to the ground pin in my experience. In my work life I have replaced dozens of them because they failed ground continuity tests. A shielded cord or just a heavier gauge cord might help. Also I run a heavy gauge ground connector from my table to the amp and I have it a short as possible. I have 0 noise issues. I do have a wireless network running in the house as well as wired but nothing out of the ordinary. Also, the nearest neighbour is 150ft away so there is not a lot of RF floating around here.
Hi All, just wanted to thank you for this post, it helped me no end as it gave me the answer to that very same problem, SL-1500C + Power line adapter = crackling noise.
For info my Powerline adapters are from Netgear.
now to find a good mains filter 😁
For info my Powerline adapters are from Netgear.
now to find a good mains filter 😁