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Michael, Customer Service
Category: Home Theater-Stereo
Satisfied Customers: 9568
Experience:  I have worked with home theater systems for over 20 years.
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I have an issue with the Denon HA-1000 Head amp: Now i

Customer Question

I have an issue with the Denon HA-1000 Head amp: Now i have to MUTE the ARC SP8 preamp before switching Off the Linn LP12 turntable to play the other side of the record.
Previously with a Linn Kairn preamp with Phono MC input this was not the case!
Should i forget to MUTE the SP8, switching off the turntable makes a huge PLOC noise in the loudspeakers...
The HA-1000 is from USA 110V and is AC connected from an AC outlet of the Mc225 amp.
I was told to use a Schaffner AC filter...
This HA-1000 performs wonderfully with the SUPEX900 super MC phonocartridge.
The SP8 is AC connected to 220V, here in France and the Mc225 is 110V connected to a Step Down transformer.
Thank you for a technical advice
Let me know what do you recommend?
Submitted: 2 years ago.
Category: Home Theater-Stereo
Expert:  Aric replied 2 years ago.
Hello and sorry you're having problems. The issue that's causing the noise through the speakers is due to the Denon not providing DC blocking at the RCA Inputs of the preamp. Now, with MOST preamps there must be DC blocking capacitors to eliminate a loud thump from occurring in the system when a source device (in your case the turntable) is shut off. Since your new Denon doesn't have this filtering built in, a ground loop isolator connected between the phono stage and the preamp would be needed. A device such as the one at the link below is transformer isolated to add inductance between both the input and the ground of the source and prevent loops and thumps from entering the system (please note that RCA to 1/4" adapters must be used at both the Inputs and Outputs of this device): If you need further assistance let me know. Please do not forget to click a POSITIVE RATING before you go- as it's how I am credited for my work. You can follow up at any time, at no additional cost.
Customer: replied 2 years ago.

Hello Aric,

I'va also asked other specialist:

AudioResearch said:


The SP8 was designed to use with MM cartridges. If you use a step up xfmr. or active step –up device, you will inevitably get some hum. My best advice is to obtain a hi output MC cartridge. I have a friend who owns an SP8 and uses a Sumiko Blue Point #2 , which has 2.5 mV output and works great with the SP8.

Best regards,

Chris Ossanna

Clinique Audio told me that the Gnd Loop Isolator is a crappy solution that will not enhance the sound.

I was told to use first a good "shielded cable" between the HA-1000 and the SP8 Phono entry.

That's the reason why it's too short to give you a 5 stars satisfecit...

It may take some time before i can take the good decision...



Expert:  Aric replied 2 years ago.
The SP8 is designed to use with MM cartridges- but what you stated first was that the Linn Kairn preamp (with all other equipment remaining the same) did NOT emit the sound when the record changed sides. That being said, I was proposing the only viable solution without changing other existing equipment.
The simple solution, if you don't mind going from MC to MM is to purchase a high gain Moving Mass cartridge as the cartridge gain will be about 40 DB higher than the noise and therefore the volume level needed from the preamp will be much lower in reference eliminating the PLOC sound.
The transformer isolation device I suggested was the only solution you could go with, without changing any other equipment.
Customer: replied 2 years ago.

Hi Aric,

Yesterday i paid a visit to a high end Hifi Shop! They proposed an Ortofon High end RCA/RCA cable with a GND cable ended with a fork on both sides... The cable is pricey at 235€...

I prefered not to buy it and use a high end Interconnect shielded Wireworld pair of cable RCA/RCA + a DIY cable ended with a fork at both ends to connect from the GND of the HA-1000 to the GND of the SP8.

The sound is terrific and the parasite noise when switching of the turntable is now diminished and acceptable in only the right speaker...

I will choice to do nothing else but use the MUTE of the SP8 before switching off the turntable.

I'm happy since the sound is really terrific and outperforms what i previously had with the Linn Kairn preamp.

I will not try the GND loop isolator since the cable are poor and not shielded and may worsen the terrific sound i get!

Sorry but i may ask a refund of my 36€ spent on your website



Expert:  Aric replied 2 years ago.
Bernard, I have nothing to do with billing, I am an independent tech working of my own time here- not a site employee. You would need to contact customer service from the home page for billing issues.
Expert:  Aric replied 2 years ago.
FYI the ground loop isolator IS indeed fully shielded, as I build vacuum tube preamplifiers and amplifiers, and the transformer based shielding does NOT degrade the audio quality regardless of what the high end shops may have told you. To each their own, and while my solution would have worked- you chose a different path, no worries. Best wishes.
Customer: replied 2 years ago.

hi Aric,

do you recommend this cheap GND Loop Isolator?

What worries me is the cabling with no apparent shielding?

I may buy it to test if it works as you said!



Expert:  Aric replied 2 years ago.
Hello, I wouldn't try something as inexpensive as that unit- as it's designed for car stereo and I wouldn't trust the build quality.
As far as no apparent shielding though- it is shielded. The cable pigtails have a shield (drain) over the positive wire and the inside has a PCB that routes the ground around the signal paths. Even inside of your equipment, there are all PCB's where the cable shielding is no longer present. Noise is kept out by keeping signal paths away from ground- except in the case of your turntable, the noise is getting into the audio path due to improper grounding/noise rejection, which is why you hear the noise.
Expert:  Aric replied 2 years ago.
I would instead suggest the one at the link below:
Customer: replied 2 years ago.

hi Aric

I've just order your suggested GND Loop isolator but from Baxshop at a very affordable price at 50€ only!

ART DTI Dual Transformer & Ground Loop Isolator

I will receive it next wednesday the 10th of june! After testing if it works as expected i will send you the required 5 stars!

kind regards


Expert:  Aric replied 2 years ago.
Thank you for the follow up Bernard and let me know what happens.
Customer: replied 2 years ago.
Hi Aric,
Unfortunately this ART DTI device was not the expected miracle item!
Today i emailed back to baxshop in order to send back this useless item...
Since it needs an extra cable between the HA-1000 & the ART DTI with also GND plugged it's not the best for the sound since the shorter the way best it is! I couldn't find any improvement at at versus my DIY solution very simple: a GND cable between both amp and preamp chassis also connected to the HA-1000 GND chassis and that's all.
Since there is a MUTE btn on the SP8, the only thing I have to do was to use this MUTE before stopping the turntable in order to play the other side.
So frankly, your recommandations for GND Loop Isolator was not a 5 stars solution for my issue! I will ask for a refund since yours recommendations were not useful to carte my issue.
Expert:  Michael replied 2 years ago.
Hi and thank you for choosing Just Answer.
I am Tech Michael and I will be assisting you today.
Please be patient as these are technical questions that may require a bit of conversation to solve. Also remember to be detailed in your description of the problem. That will help me make a diagnosis quickly for you.
How old is your Amp?
Also this sounds like a grounding issue and Aric is correct in what you should try first. It may not solve the issue but its a start in the right direction for sure;-)
Thank you
Tech Michael
Customer: replied 2 years ago.

Hi Michael,

I've fixed the GND issue by myself with a simple DIY Gnd cable and that's it!


I don't need anymore help and what i need is a refund since Aric's solution with his GND Loop isolator was not successful for me!

Expert:  Michael replied 2 years ago.
I knew it would be a ground issue and thought a simple wire would do it;-)
Have a great day and please rate kindly before you go.