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Old 5th July 2012, 02:59 PM   #1571
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Quote:
Originally Posted by merlin el mago View Post
Zobel cap 10uF 63V Arcotronics MKT polyester.
would be very Interesting to know If you have tried other caps here as this Is critical for overall sound

I have used 4,7 uF Axon PP and 10 uF Vishay MKT1822 polyester

MKTT1822 Is dull and plastic than Axon which Is nothing special but better
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Old 5th July 2012, 03:51 PM   #1572
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Default MKPs and long leads...

Aren't the long leads on bigger metallicized polypro caps a problem with inductance and noise pickup? I use Mundorf MKP 4.7 uF for the zobel, and it barely fits with some creative lead bending. For analog line level circuits I have been using a 100 uf Silimic II, bypassed with a 0.1 polystyrene on the other side of the board and this sounds good (adding the polystyrene really seemed to make a difference in transparency) for vref filtering
Any bigger MKP caps would have long flying leads and I would expect that to create more problems than it solves?
Not really a fan of polyester caps, are they any good for sonics? They are more compact!
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Old 5th July 2012, 04:11 PM   #1573
Salas is offline Salas  Greece
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I prefer a good layout with smaller components and shorter leads always. Try bypassing the Vref electrocap with 10-100n Silver Mica right on its pins under PCB. I had good luck with C0G also. See how you like it VS polysterene bypass. Some MKTs can be really good. Try Vishay etc.
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Old 5th July 2012, 05:13 PM   #1574
Salas is offline Salas  Greece
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Quote:
Originally Posted by samoloko View Post
would be very Interesting to know If you have tried other caps here as this Is critical for overall sound

I have used 4,7 uF Axon PP and 10 uF Vishay MKT1822 polyester

MKTT1822 Is dull and plastic than Axon which Is nothing special but better
Compare same values.
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Old 5th July 2012, 05:53 PM   #1575
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Quote:
Originally Posted by barrows View Post
Aren't the long leads on bigger metallicized polypro caps a problem with inductance and noise pickup? I use Mundorf MKP 4.7 uF for the zobel, and it barely fits with some creative lead bending. For analog line level circuits I have been using a 100 uf Silimic II, bypassed with a 0.1 polystyrene on the other side of the board and this sounds good (adding the polystyrene really seemed to make a difference in transparency) for vref filtering
Any bigger MKP caps would have long flying leads and I would expect that to create more problems than it solves?
Not really a fan of polyester caps, are they any good for sonics? They are more compact!
Quote:
Originally Posted by Salas View Post
I prefer a good layout with smaller components and shorter leads always. Try bypassing the Vref electrocap with 10-100n Silver Mica right on its pins under PCB. I had good luck with C0G also. See how you like it VS polysterene bypass. Some MKTs can be really good. Try Vishay etc.
I bypassed lytic Vref cap with a small teflon FT-2 15nF 200V before was a big FT-3 100nV 600V. Polysterene for Vref cap bypass is also good seems working more in high treble like super tweeters the sensation of air & atmosphere is incredible but lacks a little bit of body that has the teflon so is up to the own taste the election both are superb, about silver mica is a little bit like crystal sound my opinion is the sound between the teflons & polysterenes also very good. MKP1837 10nF can be another option the sound is between teflons & silver mica.
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Old 5th July 2012, 05:56 PM   #1576
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Quote:
Originally Posted by Salas View Post
Compare same values.
And if possible same voltage.
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Old 6th July 2012, 11:14 AM   #1577
CeeVee is offline CeeVee  Portugal
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Default Temperature drift

Hi,

I've built a SSLV1.1 using my own board for a BIII.
The issue i'm struggling with is some temperature drift, there is about 100mv drift downwards until it stabilizes.

I did burn in tests for 48hours at full load ( circa 700mA ) and it remains rock solid and very clean.

Problem is that if i want 5.25 V effective during normal operation it has to be adjusted for 5.35 V cold.

BIII specifies upper limit as 5.5 V so I'm within safe limits but only just.

Any suggestions on how to minimize further the temp drift ?

R1 is 3R3 and transformer is 9V Toroidy, as can be seen from picture i use 4 ref leds.

Previous try was with R1 1R5 and 3 leds....not very different results..
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Old 6th July 2012, 11:29 AM   #1578
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How fast does the circuit reach the final output?
And what parts are you using for the V reference?

First thoughts might be different sink arrangement for the transistors to allow them to reach cruising temperature faster (without compromising safety), lower ppm resistors and more temperature stable parts in the voltage reference
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Old 6th July 2012, 01:22 PM   #1579
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Default No worries!

The B-III has onboard local regs, as long as you are within the sweet spot of their operating range with the pre reg you are fine. The Tridents run great from 5.1-5.4 volts, so there is no need to worry about a little drift, and .1 V of drift with warm up is normal. Set the Salas for 5.35 cold as you have, and as long as the stable/warm V is 5.1-5.3 volts you will have optimum performance. No circuit is going to be exactly the same cold as it is warm.

Make sure you measure for AC on the Salas output to check stability, reading should be the same as shorting the two probes together. Sorry, missed your scope shot! All looks good there, clean output...

Last edited by barrows; 6th July 2012 at 01:25 PM. Reason: added info...
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Old 6th July 2012, 02:58 PM   #1580
CeeVee is offline CeeVee  Portugal
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Quote:
Originally Posted by dimkasta View Post
How fast does the circuit reach the final output?
And what parts are you using for the V reference?

First thoughts might be different sink arrangement for the transistors to allow them to reach cruising temperature faster (without compromising safety), lower ppm resistors and more temperature stable parts in the voltage reference
Thanks for the reply,

Settling time is around 5 mins, its probably true that the sinks used are way too big, but there will be other power supply boards bolted on.
This is the one i will be using for my all singing all dancing BIII as a PSU plugin module with power for IV and FIFO and USB 2 I2S....and TFT display.

ref parts are 50 ppm resistors and 4 green leds.

I'm just a bit concerned that the trimmer might be contributing more than it should.

Anyway my objective was to compare notes with others on the forum on my results and it seems that 100mv settling drift is considered average.

I'm quite happy with the full load output: very stable and clean so i guess that as long as i'm below 5.35 V cold start i'm very well :-)
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