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Old 13th July 2010, 01:29 PM   #1771
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Default Hum

Salas, in my case hum is not too loud. Usually I hear the hum when switching on my equipment (in this case a Tripath2020). Not really loud, but would rather get rid of it. Will try the mod anyway since one gets rid of the relay contact in signal.

Regards Ernst
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Old 13th July 2010, 01:31 PM   #1772
Salas is online now Salas  Greece
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OK, let us know. Cheers.
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Old 13th July 2010, 02:34 PM   #1773
Malka07 is offline Malka07  England
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Well as i felt so honoured to be chosen by Salas to do the beta testing for the hum(buzz) problem when switching the preamp off whilst leaving the poweramp on, I decided not to delay but to get down to it straight away...

The mod itself was a fairly simple to do and took about 20mins.

Click the image to open in full size.Click the image to open in full size.

The good news is that, it did indeed get rid of the hum(buzz) when leaving on the poweramp and turning off the pre...

The bad news is for me, that music is only coming out of the left speaker, nothing from the right!!! I will have to go back and inspect my solder joints...
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Old 13th July 2010, 02:45 PM   #1774
Salas is online now Salas  Greece
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Hope its no collateral damage. Tap on the relay with a screwdriver first, maybe it got a bit hot with soldering and stuck. After all is well again, see if it gets a bit cleaner by skipping the contact. Thanks for your initiative.
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Old 13th July 2010, 03:40 PM   #1775
Malka07 is offline Malka07  England
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PHEW....more good news

No sound coming out of the right speaker was nothing to do with the mod...infact i found that the Ground(input) had come away from the board...

Click the image to open in full size.

So i hardwired it to the leg of the 220k resistor...

Everything back to normal, Wonderful sound and no hum(buzz) when turning off preamp before poweramp

As for it sounding better because of not being in contact with the signal path...i think you would have to be hard pushed to tell a difference...however it is nice to know that its not in the path(peace of mind) and also fixes the hum problem, so definetly recommended from me.

P.s I hope i have attached the pic correct this time Salas, i resized it to 1024x768 and then i removed the .Th in the link...is it correct???
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Old 13th July 2010, 03:46 PM   #1776
Salas is online now Salas  Greece
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Yes, good size this time. Difficult to photo the black shiny board. So our official grounded cross beta tester (with a cross on his flag no less) says: Any guy with a turn on/off buzz, Oenboek's cross is the beaten path. Two bird's with one stone, you never walk alone.
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Old 13th July 2010, 04:53 PM   #1777
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mmmmmm interesting topic. I will try later at home if I get some noise when turning off the amp. If so, it is a good mod to do and specially getting the relay out of signal path.
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Old 13th July 2010, 04:57 PM   #1778
Salas is online now Salas  Greece
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First I thought it was during on (sithot28)...then its when off... If it works without any other problems for 1-2 days, let me know so to ask crt to incorporate it in the blue if I can find him soon enough and he has the time.
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Old 14th July 2010, 12:37 AM   #1779
mdynac is offline mdynac  United States
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Default my DCB1

well this last weekend it rained alot so i could not golf.....soooooo i decided to whip up one of my DCB1 boards. everything matched blah, blah, blah......however i kept it stock except for R1 i put 3 68 ohms in there, its like 23 ohms or so. all the voltages and currents are good, but i will tweak it up later. no fancy dancy parts yet.....

since i have 6 Harman/Kardon recievers i decided to gut one except for the power amp, and make me a kewl integrated.

i still have work to do, the power amp is not hooked up in there yet, and i must fabricate some brackets to mount the buffer. wow this thing sounds great, i'm driving an adcom gfa-535II with it. it blows away the Anthem Integrated 1 preamp section i was using.

Salas i would like to thank you for a fine, fine project, i would recommend this buffer to anyone and everyone.

i don't have all the input relays in right now, so i use a Niles Audio switch.

now i can sit and enjoy the warm glow of leds thru the faceplate where the tuner used to be!!!!!!!

the HK 430 has quite a unique power amp, it uses all the same NPN transistors in a push-pull output stage.....some say that is why this model sounds so much better than any other HK of the same vintage. i agree, or i wouldn't own 6, best bargain in audio..... also notice the beefy power supplies for each chanel. i can email you folks a copy of the service manual with schematics if you like. let me know.

once again thanks Salas, another satisfied diy'er here, one step closer to audio nirvana.
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Old 14th July 2010, 12:42 AM   #1780
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I guess it has a solid state phase splitter and then all npn ala tube power amps topology. Nice to know you are chuffed. Enjoy.
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