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Old 8th April 2009, 02:53 PM   #1591
RCruz is offline RCruz  Switzerland
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Default BIG improvements ahead !!!

1st - Again following Salas indications, I bought some mogami teflon coax and decided to replace the solid core copper wire used to bypass the 101b MC stage, with a small lenght of the coax.

Inittially I heard "thin" sound, but with more detail. after 12 hour burn in, the bass came alive "full on".

Multi thin stranded OFC wire is better to carry signal than thick solid core I guess. (Must have something to do with superficial conductivity, in thick wires there is a small amout of frequencies that use the outer copper layers while low freq travels inside the wire... I believe this causes some "bracking" to the signal depending on the frequency.)

2nd - Also based on previous readings in this forum, I decided to bypass the 4.7u obbligato Riaa output caps with a russian teflon. For now I am using Teflon K72-6 0,047uF (47nF) and the results are awesome. The teflon caps do not add any signature to the sound (unlike the PIO I used before that give a Big Guitar/Jensen effect). The teflon provide an enourmous increase in detail and bass extension without affecting the main cap sound.

I am now waiting for some 100nF FT-3 to experiment so I will be reporting soon.

Ricardo
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Old 9th April 2009, 03:32 PM   #1592
RCruz is offline RCruz  Switzerland
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Today I am etching the pcb for the second shunt. (I revised the initial layout in order to get more space for the mosfets.

It will be a clone of the first one, using exactly the same components, so I expect I will get the same performance and voltage output.

As the TX is quite big, I can not fit a second one, so the shunt will be sharing the same winding.

As I do not have enough parts now, for the rectifier and smoother cap, I will be using only one inittially and will build a second one latter.

Resuming: 1 TX, 1 rectifier bridge, 1 smoothing cap, 2 shunt.

Ricardo

PS: in attach you have the revised pcb.
Attached Files
File Type: pdf shunt evo 9.pdf (32.0 KB, 114 views)
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Old 9th April 2009, 06:04 PM   #1593
Salas is offline Salas  Greece
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2X rectifier is ''or'' Boolean I think, and it helps towards individualism of common trafo double psus.
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Old 9th April 2009, 11:49 PM   #1594
RCruz is offline RCruz  Switzerland
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I know... but I must get the right parts... maybe I will order tomorrow
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Old 11th April 2009, 06:36 PM   #1595
RCruz is offline RCruz  Switzerland
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Default Help needed

Hi Salas

Just built the second shunt but I am having trouble ... It takes 5 minutes to reach 26.6v and can not hold a load of 1k. (When loaded the voltage drops to 0.2v )

Strangely, the mosfets do not heat at all.

What should I look for ?

Ricardo
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Old 11th April 2009, 06:41 PM   #1596
Salas is offline Salas  Greece
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Look for wrong implementation of schematic. Do you still have your original so to compare it too?
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Old 12th April 2009, 12:34 AM   #1597
jims is offline jims  United States
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Salas

I started building one for my DL-160. Have you tried a capless B1 buffer on the out, like your B1 schematic i?

Thanks
JimS
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Old 12th April 2009, 12:57 AM   #1598
Salas is offline Salas  Greece
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No, Kent was telling me that he would at a point. You can't avoid the output capacitor here though. It's a single ended supply.

*I am referring to using a B1 type buffer in the phono itself instead of the standard integrated one.
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Old 12th April 2009, 11:15 AM   #1599
jims is offline jims  United States
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I was thinking about trying the turbo B1, I am building with the boards patrick, as an output
buffer.

Regards

JimS
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Old 12th April 2009, 11:26 AM   #1600
Salas is offline Salas  Greece
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Can you explain that better? You want to substitute the standard phono buffer 3rd stage, or you want to use a 2 stage phono plus a cap-less B1? Can you point me to the schematic you are building, so I can check it out with a B1 style tail?

EDIT: You mean that surface mount for DIP8 job I guess. I have listened to a 2 stage phono plus my capacitor-less B1 as a buffer/volume. They work fine together. So your plan is analogous and I see no problem about it.
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