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Old 16th May 2012, 02:56 PM   #2011
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Quote:
Originally Posted by Bonsai View Post
Jcx or jneutron did some calcs a few month back that showed you needed significant currents in the proximity of ferrous material to cause problems. Steel provides a great shield against EM radiation, and in the case of aluminum/aluminium you get screening from electrostatic coupling provided of course in both cases you take care of grounding etc. iI may be that where there is a perception that an amp sounds worse in an enclosure, there are other issues that are at play eg grounding, cable dressing/routing etc.
In the days of Marantz CD63 I noticed a difference in sound between some models. Upon some investigating I found that the only difference between two models was that one had the inside of the casing coperplated as well as the small shield casing around the discrete opamp section. The rest was identical. The difference was crearly audible.
Ill probably need a Molecular scientist to explain this one to me..........

Ps I forgot the copperplated version also had copper screws.
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Old 16th May 2012, 03:14 PM   #2012
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Sakis I understand that the NVA is hardwired, no pc board or circuit board. This would make a difference in to the sound, the quality and material of the board also affects the sound when a board is used.
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Old 16th May 2012, 03:39 PM   #2013
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Quote:
Originally Posted by nikosokey View Post
Thank you for your opinions
But I created this box to put the transformer inside filling the box with a special material and placing soft feet to reduce vibration.
So far I've done something wrong;
Gm I noticed the sound is excellent, but needs to make some changes as you told me!
Thank you very much!
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Old 17th May 2012, 07:48 AM   #2014
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Default Golmund clone

Quote:
Originally Posted by AndrewT View Post
Niko, 3pair output stage.
What output bias current, what output quiescent dissipation, what temperature for Tj, Tc, Ts & Ta?
with R20 390Ω =100-110 ma
with R20 360Ω =50-60 ma
Rail +/- 70V
100 ma = 5 W quiescent dissipation per device
50 ma = 2.5 W quiescent dissipation per device
Heatsink SK56 Tj, Tc, Ts & Ta?
See:
http://products.semelab-tt.com/pdf/A...nNoteAlfet.pdf
Take a calculator you are good with it.
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Old 17th May 2012, 08:14 AM   #2015
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Quote:
Originally Posted by homemodder View Post
Sakis I understand that the NVA is hardwired, no pc board or circuit board. This would make a difference in to the sound, the quality and material of the board also affects the sound when a board is used.
+1000 i agree but here the question is about the enclosure

i wonder how my latest product will sound since its made with the bottom part of the enclosure from aluminum ( helps cooling a bit ) while the top is made of iron ....

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Old 17th May 2012, 11:35 AM   #2016
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by nikosokey View Post
............Rail +/- 70V
100 ma = 5 W quiescent dissipation per device
50 ma = 2.5 W quiescent dissipation per device
Heatsink SK56 Tj, Tc, Ts & Ta?
....................
100mA and 70Vce = 7W per device.
3pr results in 42W into the sink.
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Old 17th May 2012, 12:02 PM   #2017
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Default Golmund clone

Correct my friend Andrew
I count for 50V +/- rail
Regards Nikos
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Old 17th May 2012, 01:56 PM   #2018
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Quote:
Originally Posted by sakis View Post
but here the question is about the enclosure
I think there will be no big issue with metal casing if the main source of radiation (transformer) is outside of the enclosure.

But your toroidal transformer tends to have its magnetic flux confined to its core, so more safe than EI transformer.

I prefer to shield the sensitive parts of the amplifier, from RCA to input stage, because the shield material required is few. If necessary the cable is as short as possible.
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Old 23rd May 2012, 07:53 AM   #2019
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Default pcb ver 2

I have finished the new version of pcb :

1. The 2n5565 has been modified so that if you have a dip or soic version (LSK389A), you can still use it here.
2. The T3/4, T5/6, T7/8, T9/10 transsistors pairs are re-oriented that they can be stuck to a metal strip for better thermal coupling.
3. The additional T23, T24 can be implemented by using a small piggy board. Please see the attach for new schematic


I think someone mentioned using IRFP240/9240 pair by adding a Vbe. Someone please suggest one so I might included this too?


Can someone please tell me how to attach more than 1 files to a post?
Although I had checked, hope someone can check my work again.

I had order of 10pairs at hand. I would start a GB if anyone is interest.


BP
Attached Files
File Type: pdf GOLDMUND NEW SCHEMATIC PDF..pdf (121.0 KB, 761 views)
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Old 23rd May 2012, 04:39 PM   #2020
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pcb layout :


4shared folder - goldmund-2
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