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 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

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PostPosted: 28 Aug 2009, 05:56 
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Joined: 29 Aug 2008, 02:48
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Location: Athens, GREECE
I took the challenge a month ago. Sounded quite qood. First tweak i did, i put away the first WIMAs caps in signal input. I can't real tell if the usage of NE5532 is only buffer or a gain stage of 2 or 3. Sounded a little louder with the same input signal than my ex LM3886 GC (without any other input stage). If ihave the time, I will try to trace the board, see what value is the NE5532 feedback resistor and tell what the gain really is.in


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PostPosted: 28 Aug 2009, 08:36 
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Location: Duesseldorf, Germany
Hi aros3,

this is really a nice build and a fine enclosure... Good job :up:

Do you also have some shots from the inside??

And - maybe you could help us a little bit. We have a thread here about a LM3886 and NE5532 based board from the "bay" that must be
connected to a 24-0-24 transformer. The problem is, that the connections from the board are not marked or described on the top. I have only
an idea about the connections, but not very accurate informations to it. Maybe you know the boards or you got the same boards??

The thread: http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=994

Thanks a lot and welcome to the forum ;-)

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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PostPosted: 28 Aug 2009, 12:35 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Hi aroS3,
Looks good. Can you post a photo of the inside or the PCB? With the Wima caps it sounds similar to the eBay modules that Tom referenced.
Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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PostPosted: 30 Aug 2009, 13:01 
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Joined: 29 Aug 2008, 02:48
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Location: Athens, GREECE
Hi mates,
Connections marks are on the bottom side of the board, at least on mine. I 'll took internals photos as soon as i return from short holidays.
Regards George


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PostPosted: 19 Dec 2009, 13:05 
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Joined: 27 Aug 2009, 15:19
Posts: 197
Location: Sweden
Hi Guys,
little bit late but anyhow so those TO-220 ic's are 1: 7812 and 1: 7912 regulator.
just got myself a pcb of this amp without components thou i trust myself more in choice in quality.

Regards
Kjell.


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PostPosted: 26 Sep 2011, 22:23 
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Joined: 26 Sep 2011, 22:19
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I also bought this preamp from eBay. Did anyone figure out the connections? Or have a, un, schematic?

Thanks!


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PostPosted: 27 Sep 2011, 13:41 
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Hi Dclapp and welcome to the Forum.

Yes - I can remember this threads...
The OP wrote that the connections are printed on the solder side (back side) of the boards, directly at the terminals.

AFAIK there are no valid schematics available.

The only hint i can give you is to use the google picture search for "2 x 68W Watt LM3886 + NE5532".
Some layouts for the LM1875 are on the web (hifidiy). IMO - they should be very close to the 2xLM3886 circuit.
The cicuitry of the output stages could be a copy from National's Appnote 1192 with slightly reduced gain.
But, this lines above are just speculations!!

My LM3886 amp is now driven by a DIY "B1" frontend (since 2 weeks). It relly seems to be good improvement.

I would suggest to use a Burr-Brown OPA 2134 instead of the NE5532. Sonically it's way better. Just my :2c:.

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Cheers,
Tom.

Some of my projects: TDA2050 Chip Amp, the LM3886 Gainclone Thread and the Szekeres Headamp Thread.


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