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Old 1st September 2006, 12:59 AM   #11
jarthel is offline jarthel  Australia
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Quote:
Originally posted by ghpicard



I built one with a non-regulated but heavily filtered PS, with 45 output tubes, and custom built transformers, and it sounds fine to me. I'm using it without pre with an unmodded DVD player as a source until I can get something better, and have previously used it with several other digital sources and a tape deck (ugh) and it works fine.
You can use an EL84, an SV83 (P15P) or a C3m as a driver... I have used it with a couple of the first two and it sounds fine to me...

A pentode driver in pentode mode has its advantages.

Now, Katapum, if you could be more specific on your thumbs down, that would add to the discussion and to the OP request for help.


Gaston
without a pre, how do you control the volume?
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Old 1st September 2006, 01:10 AM   #12
arnoldc is offline arnoldc  Philippines
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put a volume pot in front.

for your requirements, i would support the JE Labs 300B DX (and use 76 in front). Not because it will be ultimate in sonics, but it will provide you a musical platform to start with and when your hand get itchy to mod, you have a good place to start.
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Old 1st September 2006, 01:23 AM   #13
jarthel is offline jarthel  Australia
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Quote:
Originally posted by arnoldc
put a volume pot in front.

say thorsten's legacy has no pot in the schematic.

Is it as simple as wiring a pot to the input so I do not need to use a preamp?
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Old 1st September 2006, 01:52 AM   #14
mach1 is offline mach1  Australia
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If the legacy doesn't have enough gain as is, you can always increase the value of the C3M plate resistor (within reason) to increase its mu.

The downside of this mod is increasing the output impedance of the driver stage and bringing the far left of its loadline nearer the kink.

pm
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Old 1st September 2006, 01:57 AM   #15
jarthel is offline jarthel  Australia
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Quote:
Originally posted by mach1
If the legacy doesn't have enough gain as is, you can always increase the value of the C3M plate resistor (within reason) to increase its mu.

The downside of this mod is increasing the output impedance of the driver stage and bringing the far left of its loadline nearer the kink.

pm
as it is, the legacy has no built-in volume control. Please stay away from suggestions on amps without volume control. Unless you have an idea on how to include a volume control.

I know a preamp does more than volume control but I want to limit the discussion to that for now
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Old 1st September 2006, 02:07 AM   #16
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Just to answer your question... I added a rotary switch with selectable fixed resistors (a stagged pot). Not the ideal but it was a gift from a friend and I also cant't get make-before-break rotary switches so R-2R ladders are out of discussion.
It's the same you will get if you put a "passive preamp" between your source and your amp.

OTOH, as arnoldc told, the JE300 is a good platform to start. Not my cup of tea, I prefer the WE91A-like topologies, but it has its followers.

Gaston
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Old 1st September 2006, 02:14 AM   #17
jarthel is offline jarthel  Australia
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Quote:
Originally posted by ghpicard

It's the same you will get if you put a "passive preamp" between your source and your amp.

you're right. didn't thought of that.
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Old 1st September 2006, 02:17 PM   #18
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Another vote for the JEL 300B. OK, so mine isn't exactly the same but close enough and I can't complain. Making it a stereo version makes it slightly cheaper. I did that at first but then converted to dual monoblock just to see how big the difference is. Not much sonic difference but my power tranny/trannies run cooler and B+ is slightly higher. I also tried different rectifiers, caps, resistors, grounding schemes etc.
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Old 1st September 2006, 08:41 PM   #19
tinitus is offline tinitus  Europe
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I dont know if you only need schematic or what, but as integrated complete kit this surely looks nice, doesnt it

http://www.hificollective.co.uk/kits...epictures.html
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