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Panelhead 11th September 2004 03:10 PM

Transformer coupled linestage
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After tyalking about it for a year, finally built it. Learned a lot about layout and grounding while sorting out a Hiraga Le Monstre. This can be as big as circuit details.
Here is the front. Excuse the pictures, had to crop to get through

Panelhead 11th September 2004 03:18 PM

Back View
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Single 3 pin locking DIN is power in. The other pair is different and is connected balanced out. The power is a Switchcraft, and output Deltron. They are not totally compatable to keep it straight

Panelhead 11th September 2004 03:22 PM

Circuit Board
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Top View of the active circuitry. It is a circuit provided by Steve Eddy, his Tao headphone buffer. The rest of the 8 parts are on the bottom of the board.
This circuit has proven better than any other I have tried. Cleans the sound up and can drive anything.

Panelhead 11th September 2004 03:25 PM

Power Supply
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Like any amplifier, the results are only as good as the power supply. The remote power supply uses a 317/337 regulator pair. The output is passively filtered with a C-L-C-L filter before going to the linestage

Panelhead 11th September 2004 03:30 PM

Inside the box
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Power goes to a pair of 55,000 ufd Jensen 4 pole caps, and board has local bypassing and filtering. Both channels share the main suypply.
The output transformers are LO410 S & B. Left over from a disc player exercise. Big beefy chunks of iron.
The pots for now are stereo Alpha 50K stereo carbon, wired to make a 25K mono. Waiting on some log taper PEC to try.
Drive shafts had to be chopped to fit.

Panelhead 11th September 2004 03:38 PM

Another angle
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The box is from England, diecast aluminum. Lined with mu-metal. Cannot hurt, sitting between two power supplies on my rack.
Best of all, the sound is richer, better timbre, seems almost holographic.
Previous line was the same Tao buffer with out the Jensens, output transformers, and the lined box. It seems more sterile, less harmonic. If it is added distortion from the output iron, it sure is pleasant.
Listened to a 7500.00 linestqage at my home a month ago. It did not comparte well with the old unit. This new one even caught my wifes attention. She asked what I had done to the system. She very seldom comments on the sound coming from my room.

Panelhead 11th September 2004 03:50 PM

In action as I type
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Top to bottom,

Micro Seiki DDX-1000, OL-RB-250, Denon 103R

Pearl phono with built mc headamp

Pioneer TX-9100 with power supply and filter mods

Marantz SA-8260 with mucho mods

Linstage flanked with its power supply and one for Pearl.

Hiraga Le Monstre, original transistors, C-L-C-L-C power supply, 350,000 ufds of Jensen four pole caps. Seems like a lot for a 5 watt per channel amp.


Steve Eddy 12th September 2004 05:37 PM

Nice job, George!

I envy you. I couldn't work in such tight quarters as that without the whole thing being smashed to bits at some point. :)

Can't seem to spot the output iron in the photos. Am I missing something?


Panelhead 12th September 2004 07:43 PM

Better view
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Originally posted by Steve Eddy
Nice job, George!

I envy you. I couldn't work in such tight quarters as that without the whole thing being smashed to bits at some point. :)

Can't seem to spot the output iron in the photos. Am I missing something?


That part is cropped out. Here is an inside shot of the business end. The 4 pole Jensens, LED buffering resistors, mumetal lining, jacks, and S & B LO 410 line transformers are shown better.
The S & B iron is very large for its use. The -3dB points are 10Hz and 3Mhz. This is loaded with 600 ohms, not 25K.


carlos671 17th October 2005 06:57 PM

advice on pre power combo
Hi, am i right in thinking you are running a pre/mono block combo with t amps? if so would you be able to give me some more details as this is what i'm lookin to construct


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