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Old 20th September 2012, 03:40 PM   #341
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bcmbob
thanks! I will try later connecting Alps alone, hope it would solve the issue as active preamp is an overkill anyway, imo. Perhaps Salas hot rodded buffer that I'm building now would be even better here.

AndrewT
I will check it with my AB class amp with 2x100VA toroids, lets see what this meter shows there.
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Old 20th September 2012, 04:07 PM   #342
atupi is offline atupi  Romania
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I use the same config: passive attenuation (Alps) > DCB1 (hotrodded) >MyRef
DCB1 improves a lot mid frq (voices) and stereo image.

Last edited by atupi; 20th September 2012 at 04:13 PM.
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Old 20th September 2012, 11:50 PM   #343
bcmbob is offline bcmbob  United States
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You knew they were comming

BLAT I - Soft crusted Belgian 1 hour from the bakers oven. A little MW with a splash of Italian Dressing.

BLAT II - Hard crust light sourdough, Canadian Bacon, topped with chopped onion and avocado.

Two of the best momoblocks I've ever built. One actually has high quality chips installed

Thanks Jac
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Old 21st September 2012, 12:02 AM   #344
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Quote:
Originally Posted by dtses View Post
mine has very noticeable grounding sound (not placed in enclosure yet) - some kind of low frequency hum even if the pcb's input socket is completely disconnected.
With input disconnected a slight hum is perfectly normal but it should disappear completely with source connected.

Quote:
Originally Posted by dtses View Post
the preamp I use has approximately 3x gain, 10k Alps pot and it seems it's a bit overkill. Is everybody using just a pot or some passive preamp? What would be better?
I'm using plain 10K pot, DCB1 with 10k pot, AV receiver pre-out without problems or hum.

I've built too a JC2 but I get hum.

BTW no preamp is needed with the MyRef (Rev C or FE)

Quote:
Originally Posted by dtses View Post
every time I switch off my preamp I get very loud snap or crack in the speakers, then relay clicks, LED is off and amp needs to be turned off and on. Is there any simple output stage that could be added after opamp to prevent this? Moreover, I have already burned somehow 1R resistor and T201 doing similar switching yesterday, not sure was it the volume level or the series of turning on and off my preamp, but in the end i've got not working FE and spent hours to figure out what was fried...
This is not normal, definitively.

Are you sure you correctly wired signal hot and ground return?

If you invert hot with ground return hearing hum is a certainty...
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Old 21st September 2012, 12:04 AM   #345
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Are they organic sounding?
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Old 21st September 2012, 12:28 AM   #346
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Quote:
Originally Posted by ClaveFremen View Post
I've built too a JC2 but I get hum.
No more hum from my JC2 as a pre for the FE...it was simply a bad contact through the Molex connector...

So, in my case, I can't get hum from any active/passive pre I've tried (if correctly wired ).
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Last edited by ClaveFremen; 21st September 2012 at 12:33 AM.
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Old 21st September 2012, 12:53 AM   #347
bcmbob is offline bcmbob  United States
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That's great Dario, I hope you like how it sounds as much as I do.

I've been thinking about using a tiny screw terminal also on all the signal ins on the FEs, as I had a similar problem with those little spurs on the connector failing. It will be great when everything is a soldered joint.

Happy listening and let us know your impressions.
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Old 21st September 2012, 07:53 AM   #348
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thanks, Dario, for help

Quote:
Originally Posted by ClaveFremen View Post
If you invert hot with ground return hearing hum is a certainty...
could you please eleborate this? did you mean pot?

One more thing that would like to clarify if that is normal behaviour. Once I connect socket to the mains, push the switch on button, FE doesn't start, it does only when the switch is turned off and on again.

The other a bit confusing thing is if you play with the mains switch for several times - FE doesn't turn on any longer, you should turn it off, wait for 2-3 secs and only then it's working.
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Old 21st September 2012, 08:36 AM   #349
Marra is offline Marra  United Kingdom
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Originally Posted by Dufus View Post
Are they organic sounding?
Only after a couple of hours warm up
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Old 21st September 2012, 10:02 AM   #350
bcmbob is offline bcmbob  United States
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dtses, are you using sockets in your build? If so, are they maintaining good contact? A loose fit can easily interrupt the circuit.
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