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Old 9th December 2002, 12:34 PM   #201
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Default NFB

Thanks for the info Eric, love to learn more, wouldn't it be nicer for all newbies with a new thread regarding NFB take off point? be it point to point or pcbs.

BTW folks, I've forgotten to mention that I did try my best to ensure the hook up wire (length and size) and the exact points of soldering on the pcb track are identical on both channels.

Chris
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Old 9th December 2002, 02:28 PM   #202
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Default No Such Thing As An Ideal Conductor....

Probably a fine idea, but we can run it here for now, and if we feel like it we can do a cut/paste of these posts into a new thread, by all means - this is a subject that newbies need to understand.

Anyway, did you understand my previous post correctly ? - if so, good, if not, say so.

You say that you tried to make both channel mods as identical as possible BUT did you make sure that the add in pieces of wire directions are identical ?. - big question !.
I do not want any intruders to get into any wire directions debates here whatsoever, thankyou.
I say this because of experimentation results and N.P. (nuclear physicist) discussions.
Chris, by the fact that you are telling me that your NFB arrangement change has resulted in sonics change, you are telling me that you have a good enough resoloution system, and good enough ears - good.
So, drop any pretensions that you may have regarding if wire has any directional characteristic or not, and go do some experimenting with the same piece of wire in the layout, fitted in reversed direction, and note any fine changes (on music tracks you know perfectly well).
In my experience this is an additional effect, as has the alloy (or purity or plating) of the wire used, and also the solder alloy used, and that is another subject.

You can build the system so as to discount (eliminate and utilise) directional effects to fine tune the sound you want.

Chris, if you are still listening I can tell you more.

Eric.
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Old 9th December 2002, 03:41 PM   #203
argo is offline argo  Estonia
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Quote:
Originally posted by chris ma
Argo,

What are you using for Q3? with that heatsink I am guessing 2N1711..

Chris
Yes its 2N1711. I will try 2SC3421 as well sometimes later. First I need to change the outputs for MJ15003 because these ST Microelectronics 2N3005s are really dull sounding compared to original Motorola devices, which I had previously but broke. Right now Power Follower I am trying out occupies JLHs cabinet. Havenít done any serious comparisons between those two yet (I am lacking a good voltage source at the moment) but that they are definitely different sounding amps, is obvious already. JHL provided crystal clean, very detailed and sometimes even merciless sound while Power follower seems to beautify and sweeten things too much. Kind of comparing oranges to apples or better yet fresh lemon to honey.

Argo
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Old 9th December 2002, 05:02 PM   #204
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Eric,

Silly me I didn't think about the direction of the wires.. there is no marking on the wire otherwise it would be easy to tell, by luck I may have them in the same direction because I cut them from the same spool used the first one to match the length and cut the second one, with both wires always between my fingers and strip them both in one go in one end and the other end stripped longer due to the fact that I want them to bend the same angle and line up the different points on the tracks to provide easier soldering, yeah I think they are in the same direction, just by blind luck that I want longer stripped on one spot on the track. I'll listen to the amp more before I'll reverse the wire though.. may be some day...but other modification/fooling around with different transistors will beome next in priority. (I do believe in wire direction BTW, just a matter of why not but no back up knowledge for the subject tough)


Argo,

I am using BD139, in my dismantled JLH1996 I used 2n1711, for some reason I think the 2N1711 sound more tube like than BD139 but can not really put my finger to it. But I want to try TimA's suggestion first then I'll try 2SC3421 too, by the way what do you mean by Power Follower, a newbie question..

Chris
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Old 9th December 2002, 06:52 PM   #205
paulb is offline paulb  Canada
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Quote:
Originally posted by chris ma
Eric,
Silly me I didn't think about the direction of the wires..
Don't forget that Eric is in the Southern Hemisphere and the recommended directionality for wires is opposite for the Northern Hemisphere (although you may not notice it unless the sunspot count is high).
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Old 9th December 2002, 07:00 PM   #206
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paulb

How is your JLH progressing btw?
Chris
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Old 9th December 2002, 07:56 PM   #207
paulb is offline paulb  Canada
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Quote:
Originally posted by chris ma
paulb

How is your JLH progressing btw?
Chris
I'm afraid it's on hold at the moment. I was hoping to use a JLH design for my refurbishment of some antique powered Advents, but heatsinking proved to be too big an issue. I'm putting ESP3As into the Advents instead, then I'll revisit the JLH. I'm kind of glad I shelved it for a bit with the new information recently posted in this thread. I had one channel running but will probably start again with the latest suggested changes.
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Old 9th December 2002, 09:38 PM   #208
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Exclamation Class A

Sorry, but i am a little confused right now.. Which one of all this schematics works good. I am intrested in building some low power class A amplifier and i am asking someone who allready built some amp to give me the link or schematic. Thanks! Dragan.
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Old 10th December 2002, 09:55 AM   #209
argo is offline argo  Estonia
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Quote:
Originally posted by chris ma


Argo,

I am using BD139, in my dismantled JLH1996 I used 2n1711, for some reason I think the 2N1711 sound more tube like than BD139 but can not really put my finger to it. But I want to try TimA's suggestion first then I'll try 2SC3421 too, by the way what do you mean by Power Follower, a newbie question..

Chris
Itís an Andrea Ciuffoly's Power Follower 99 - SE class A mosfet amp. http://www.audiodesignguide.com/my/Follower_99c.gif
It's a source follower, like emitter follower - or cathode follower, with the gain less than 1, so it requires an additional voltage amplifier stage first. I just built it out of curiosity into the housing of JLH amp because I had some mosfets and big power transformator already. It needs some more heat sinks than ordinary JLH amp though.
So if I decide to keep it will have its own housing. Itís a very simple design with a little twist, as is JLH amp and sounds marvelous too, but different.

Argo
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Old 10th December 2002, 12:25 PM   #210
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Hi Drafance007,

Quote:
I can recommend these pages:

http://www.gmweb.btinternet.co.uk/

http://sound.westhost.com/jll_hood.htm

They should give you all the information you need.
Chris
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