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Old 24th August 2010, 09:54 PM   #1991
Salas is online now Salas  Greece
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That is the one that was nearer to the mains AC primary pair when was running diagonally then.

I see too much mains wiring and no shielded signal wiring. If a part of your buzz is still field related as by now half was in one channel, those things have to be taken care of. I would push the Tx back right and perpendicular if possible, but the AC looms can be as offensive. Should be trimmed given the slack created after Tx relocation. Or tucked along the metal corners.
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Old 24th August 2010, 10:09 PM   #1992
Malka07 is offline Malka07  England
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Ok Salas, i will try relocating the large toroid to the right and vertically mounted...also i will trim ac wiring and tuck into the metal groves at the side of the chassis. I will also try mounting the small toroid vertically.
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Old 24th August 2010, 10:09 PM   #1993
udailey is online now udailey  United States
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Chassis is incredible. SO jealous!
Yes, I think everyone should put 10uf - 100uf caps on their LDRs. Smoooooth.
Glad there is progress.
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Old 24th August 2010, 10:16 PM   #1994
Malka07 is offline Malka07  England
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Uriah, i hav'nt got round to bypassing the ldrs yet...but i promise soon i will...
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Old 25th August 2010, 01:48 AM   #1995
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Default buzz, buzz buzz

Malka,

if you gently slow down the fan with your fingers, does the pitch of the buzz/hum change? if so, maybe the fan is the culprit
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Old 25th August 2010, 03:45 AM   #1996
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These hum / buzz problems can be tough sometimes. I guess if it were mine I would get it "back to basics" if I had to, in order to squash the noise. Then add the complexity back in slowly, one step at time. Something bothers me about how the audio ground is arranged with that Lightspeed board. I think I would try something like woodturner-fran suggested. Disconnect the audio ground wires from the input RCA jacks to the Lightspeed board. Connect the two input RCA grounds together right there, at the RCA's. Flip the Lightspeed over and connect the 4 LDR audio grounds all together with very short wires, like an "X". Run a single wire from that center point to the RCA ground point we just made.

Now for connecting the ground of this Lightspeed, to the DCB1. Take the ground wire at the input of the DCB1 (center one of course), and try connecting it to the center of the "X". Or try running it to the RCA jack ground point. See what it likes. Try running a "bus" from the input RCA grounds to the output RCA grounds, better or worse? So, just some expermentation here.

Still noisy? What about running the Lightspeed on battery power... Lose the fan..... disconnect the extension rod from the pot.... What does that do? Quiet yet? And get those transformers all the way to the right, AC wires tucked right along the edge. AC inlet earth ground definitely needs to connect directly to chassis. My own preamp has no connection between signal ground and the chassis / earth ground point next to the AC inlet. Probably shame on me but it's silent. My Lightspeed is p2p hard wired, with the LDR's situated around a central ground run between the input and output connectors on that vero board. Just so that these audio grounds get "all the attention".

I'm sorry if I've said something dum here, it's late and I'm tired...
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Old 25th August 2010, 07:51 AM   #1997
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Any experiences with different 100F caps at the output of salas shunt?

I have ordered some Elna Silmic II and Cerafine and have also some Nichicon FG.

Perhaps someone has tested the SQ of these...
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Old 25th August 2010, 02:15 PM   #1998
westend is offline westend  United States
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Hi,
I am helping a local member to build a case and wire the "Hypnotize" version by crt. The board came to me populated. I will be changing the input wiring, the output wiring, and replacing the pot with a ladder attenuater. I will remount the IRFP Mosfets onto the bottom plate of the case.

Would someone be so kind as to post links to the schematic of the hypnotize board and the BOM? Thanks.

Attached are a couple of pictures of the mock-up. The interior dividers displayed as aluminum will be copper. This will be an effort to shield the attenuator and separate the transformer and board from each other.
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Old 25th August 2010, 03:20 PM   #1999
Salas is online now Salas  Greece
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For the circuit look in the very first pages. You are actually holding a live BOM by having an assembled unit but here is the link. GB for DC coupled B1 buffer with shunt PSUs
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Old 25th August 2010, 08:48 PM   #2000
Malka07 is offline Malka07  England
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Thank you all, for your suggestions with my hum problem...I am going away on holiday to Cornwall tomorrow and so wont be able to try the suggestions out for a while...but i didnt want people thinking i wasn't grateful...today i moved the large toroid to the right and vertically mounted it, also vertically mounted the small toroid, and i also tuck in the ac primary's into the metal grooves in the chassis all using Blu Tac

Click the image to open in full size.

The Hum, on the right speaker has almost disapeared, very very quite now...move the ear 6 inches from the speaker and the hum cant be heard. The hum on the left speaker has also got quieter, but not as quite as the right speaker...Buzz remains the same on both speakers.

Well im off on holiday see you all in a week.

Alon
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