Author Topic: isotek syncro dc blocker  (Read 1408 times)

Offline fgchong

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isotek syncro dc blocker
« on: September 04, 2013, 08:28 »
Was recommended by a fellow forumer in AA to use this Isotek syncro do blocker to eliminate dc from the ac line.  Appreciate comments and  inputs from bros who have experience in this dc blocker.

Thank You

FG
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Offline GAGA@echoloft

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Re: isotek syncro dc blocker
« Reply #1 on: September 04, 2013, 17:07 »
What make u suspect that there is presence of dc in our local ac lines?
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Offline fgchong

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Re: isotek syncro dc blocker
« Reply #2 on: September 04, 2013, 19:55 »
There is a humming noise from the mid driver of the speaker when my pre-amp is on operation mode.  The hum sound a bit like air-compressor running but at a lower volume.  One of the reason could be DC in the AC Line, grounding isssue, mechanical noise from the power amplifier.  The latter 2 were isolated, I will use a scope to check the AC  this weekend.  One of the AA forumer recommended the above.
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Offline wizardofoz

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Re: isotek syncro dc blocker
« Reply #3 on: September 04, 2013, 20:07 »
Dc on the mains will often upset a toroidal transformer and make it hum, but this doesnt normally come thru the speakers. Sounds more like a 100hz buzz you perhaps have.
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Offline fgchong

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Re: isotek syncro dc blocker
« Reply #4 on: September 04, 2013, 20:37 »
you mean second harmonics hum in the power line? picked up by the ground loop?

I must mentioned that all this happen when I used the Goldmund Telos mono-block with ARC Ref 10 pre.  The noise reduces when I used an ss pre and almost quiet if I changed the goldmund pre.

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Online watchdog

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Re: isotek syncro dc blocker
« Reply #5 on: September 04, 2013, 20:40 »
I think its coming from the pre, especially since its tube based
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Offline fgchong

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Re: isotek syncro dc blocker
« Reply #6 on: September 04, 2013, 20:52 »
I have the same hum but at lower level when I used the ACT 2, probably due to the higher sensitivity of the Ref 10.  Same with the speakers; the alto sound much louder than the Alexis. 

Will try and borrow a power amp from my pal to confirm that the root of the problem lies with the Goldmund.
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Online watchdog

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Re: isotek syncro dc blocker
« Reply #7 on: September 04, 2013, 21:17 »
Hmm. Sounds like a ground loop. Did you try disconnecting all sources from the pre and then making sure the pre and monoblocks are plugged into the same distributor ?
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Offline fgchong

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Re: isotek syncro dc blocker
« Reply #8 on: September 04, 2013, 21:27 »
I am currently using the star ground recommended by Michel of Goldmund (I met him last Sat afternoon at HER).  Currently both my Telos mono blocks are grounded to the ref 10 via rca only.  There is a slight improvement in the level but if you put your ears next the mid driver, you still can hear the humming.
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Offline 5th Avenue

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Re: isotek syncro dc blocker
« Reply #9 on: September 04, 2013, 21:28 »
Hum may also be due to equipment not hooked to common 'grounding' or there's grounding differential. In some cases, you can hear hum from power amp.

Try to isolate that your equipment circuit so they are not shared with network or cableTV equipments.

If equipment is not the issue, a hum filter maybe the solution but not ideal...cos this filter may degrade the sound.

If all attempt fails as it's a tough job isolating the source of hum. Some just live with it..if hum is not audible at 1ft away from speakers.

Cheers... :)  :) :)
« Last Edit: September 04, 2013, 21:32 by 5th Avenue »
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Offline fgchong

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Re: isotek syncro dc blocker
« Reply #10 on: September 04, 2013, 21:41 »
There should be no interference from other sources as I had a dedicated line to Hi-fi system.  Currently I used only 1 ground wire from the pre-amp back to the main.

As mentioned, you can hear the hum only if you put your ears next to the mid-driver, guess I need to live with it till I find the root of the problem.  I still suspect the goldmund.  Understand from Michel that the new Telos worked on a very wide band of frequency...
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Offline Instek_88

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Re: isotek syncro dc blocker
« Reply #11 on: September 04, 2013, 21:54 »
I used to have exactly the same problem. Humming from speakers. Its coming from the mid drivers due to the frequency of the sound. Wrote to the manufacturers and the root of the problem is ground loops.  Eventually, they helped me to solve this issue. If your manufacturer or dealers can't help you, then you may want to engage Wizardofoz to solve the problem for you.
« Last Edit: September 04, 2013, 21:57 by Instek_88 »

Offline fgchong

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Re: isotek syncro dc blocker
« Reply #12 on: September 04, 2013, 22:06 »
As mentioned, I am currently using star-ground i.e. only 1 ground return via the pre-amp and the line is a dedicate line direct to the main breaker. 

I really appreciate all these helpful advises and inputs from you guys, thank you very much......

My last bet now is the swop in the power-amp probably this weekend....
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Offline bigtree

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Re: isotek syncro dc blocker
« Reply #13 on: September 04, 2013, 22:14 »
Try changing tubes in pre amp? I got similar problem like you when I was using a tube dac.

It was a very soft buzz. But enough to drove me nuts!

Changed tubes as recommended hy one of my fren and the problem was solved.

Offline fgchong

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Re: isotek syncro dc blocker
« Reply #14 on: September 04, 2013, 22:18 »
Appreciate, bro B3.  Will do that after the swap of power amp, but the tubes on the Ref10 is only about 300 hours......

A bit off-topic, I must say I have fallen in love with Diana's voice, I will be going after your position as No 1 fan... ;D ;D ;D
« Last Edit: September 04, 2013, 22:20 by fgchong »
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