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Old 23rd June 2018, 09:53 AM   #21
DF96 is offline DF96  England
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You need to decide how much ripple you can hear (depends on speakers, room, ears etc.), then work back from the PSRR of the amplifier to determine how much ripple the PSU can emit. Or just copy what others have done.
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Old 23rd June 2018, 10:00 AM   #22
coolnose is offline coolnose  Europe
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PSUD2

You can play with this, a pretty useful tool
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Old 23rd June 2018, 11:56 AM   #23
trobbins is offline trobbins  Australia
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Also put at least four 5W resistors around each big capacitor to heat it up well above ambient temp. That will give you the warm sound you need and the lowest ESR level.
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Old 23rd June 2018, 12:36 PM   #24
jameshillj is offline jameshillj  Australia
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"I am looking for musical, warm but detailed sound."

It might help if you added some details about the query and further define the OP?

56v @ 14A is about 780va (+/- 28V rails?) - what do you need it for? What sort of amp? (ClassA, AB, D, etc)

What are the speakers (mains, surround, subs, etc) and how efficient are they (70, 80, 90 dB/W) and how loud do you play them? And what sort of music (Classical, Jazz, R & R, musac, etc) - and so on ...

Eric's report was carried out on smaller sized caps (about 100uF) using his preamplifier and they don't automatically 'scale up' to drive an amplifier/speakers and parallelling a couple of dozen of them doesn't guarantee to produce the expected results either, sorry.
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Old 23rd June 2018, 12:46 PM   #25
FriedMule is offline FriedMule  Denmark
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Thanks for your answers and thanks for the nye "toy" :-)

I found an comment from Ron AKA: Ripple current in input capacitor too high?

Is that a good rule and when "pr rail" does he mean that value for phase and the same value for neutral on left channel and again phase and neutra on the right channel or 4 times in total?
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Old 23rd June 2018, 01:15 PM   #26
FriedMule is offline FriedMule  Denmark
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Quote:
Originally Posted by jameshillj View Post
"I am looking for musical, warm but detailed sound."

It might help if you added some details about the query and further define the OP?

56v @ 14A is about 780va (+/- 28V rails?) - what do you need it for? What sort of amp? (ClassA, AB, D, etc)
Sorry for not including that is a schematic fine?
It is a class A/B amp.

I have some great errors in my calculations, so here are the new:
100W 8Ohm = 28ppV
600VA / 28ppV = 10A
28-0-0-28 10A transformer

Quote:
Originally Posted by jameshillj View Post

What are the speakers (mains, surround, subs, etc) and how efficient are they (70, 80, 90 dB/W) and how loud do you play them? And what sort of music (Classical, Jazz, R & R, musac, etc) - and so on ...
My speakers, right now are som old 88dB home build stereo speakers from a former friend that I will change in the future.

I mostly listens to classic, love the sound of a church organ but also Eric Clapton so my style are wide spread.:-)
Quote:
Originally Posted by jameshillj View Post

Eric's report was carried out on smaller sized caps (about 100uF) using his preamplifier and they don't automatically 'scale up' to drive an amplifier/speakers and parallelling a couple of dozen of them doesn't guarantee to produce the expected results either, sorry.
Lol nothing are so easy:-)
But taking out from specification, does it looks like that those on the schematic are good enough?

EDIT: forgot, I do normally play a bit louder then speak level, up to maybe 80dB
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Last edited by FriedMule; 23rd June 2018 at 01:18 PM.
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Old 23rd June 2018, 01:21 PM   #27
Mark Johnson is online now Mark Johnson  United States
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Help with my PSU
I think you may have a typo on the schematic of post #13. You show a couple of diodes in the output stage as "1N4841" but that is the part number of a 24 volt, 1.2 watt Zener diode.
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Old 23rd June 2018, 02:41 PM   #28
FriedMule is offline FriedMule  Denmark
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Quote:
Originally Posted by Mark Johnson View Post
I think you may have a typo on the schematic of post #13. You show a couple of diodes in the output stage as "1N4841" but that is the part number of a 24 volt, 1.2 watt Zener diode.
Oh yes thanks, I'll change it!
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Old 23rd June 2018, 04:22 PM   #29
jameshillj is offline jameshillj  Australia
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Ah, that's the thread with the query about the extra bridge for the 'front end' - the diagram is a bit confusing the way it's drawn.

Okay, some comments that are mostly my opinions but looking at your "musical, warm but detailed sound"part for the expected low volume of about 80dB, I think you will be looking to optimise the sound for medium power use, except maybe for the demands of the organ music low frequency response - that can be a bit tricky - the Silmic will give you a softer sound, so don't discount it, but you might find it loses bass definition - I'd be a bit inclined to just 'suck it and see' with this cap and keep a Panasonic FC in your box

I would use the 4,700uF/63 Nichicon KG (Fine Gold) for the rails on the front end gain stage, and the bypass to be polyester (MKC) instead of polypropylene (MKP) for a clear midrange - if your budget will stand it, you could really get better mids/tops with using the BHC SlitFoil caps (Kemet ALC20s, for example - actually made by Supertec)

For the output stage, I think I'd steer clear of the old Phillips BC caps, particularly the bigger sized ones - you would possibly be better off using a pair of the 10,000uF Nichicon 'Super Through' for this - it's more than big enough) to give that 'more musical' feel for the expected large transients - another one you could try here is the Epcos caps - now with TDK website but the numbers are still the same - the new snapin version of the famous B41550s are the pick (used to be called 'Sikorels') but again, not kind to the budget (not sure about this but B41560 - there's a few different ones)

The MUR860 diodes are a well-recognised diode - I suggest you look at the MSR 860 or the bigger 1560s as soft recovery diodes - the Phillips BYV 29s are similar - I recently tried some MBR 1045 that have a lower Vf and excellent (they also come in 80 volts, mbr1080)

Just a final thing - those output 0.15R emitter resistors - if you ask at Elfa, you might be still able to get those Isabellenhutte Manganin power resistors - they're definitely a softer/smoother power resistor than currently available - just a small thing but they all add up

No doubt, there'll be some differing opinions about some of the component choices and it is a bit of a guessing game without hearing any of the other bits in your system, but I used a very similar combination of components on a recent class A amplifier with excellent results, so I think this class AB one will work in a similar way.
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Old 23rd June 2018, 05:17 PM   #30
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by FriedMule View Post
There are two rectifier near the transformer and those do I know what are doing but what does the third rectifier do?
Nothing good: the circuit is worthless crap, designed by people thinking that useless complication automatically results in better performance.
The reality is that such "elaborate" schemes do in fact the opposite.

First of all, there is no need for two different bridges for the main rectification purpose: one is sufficient, and brings advantages in terms of efficiency and perturbations control. The subject has already been discussed at length.

Adding the third bridge compounds these disadvantages: because it is tributary of the conduction of diodes in the main bridges for its supply, it will be a half wave rectifier, with all the additional ripple it implies.
In short, this silly arrangement does the opposite of what it is supposed to do, and it does so at great expense, with no less than three rectifier bridges when one should be enough, plus two isolation diodes, maybe schottky for the other supplies.
At most, a second bridge could be added to generate the aux. supplies.
Both of these "normal" solutions are superior to the fancy one proposed.
Let me guess: this scheme has been designed by some true audiophile?
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