Hi,
I am unit testing the second CLC PSU, but with this one there is a difference between the positive and negative rail. What do you think might causes it? Different caps quoted error margin? Will the air coil affect the voltage?
The positive rail measured 33.2V
The negative rail at -29.6V
The transformer is a dual output 22-0-22 400VA
8 x MUR860 to build 2 bridges, then to C L C ; how does this affect the performance of the amp. Oh yes, this is measured without connecting to anything. Can I still use it?
The first CLC PSU measured at 34V both rails.
Any help is appreciated.
Regards,
Chris
I am unit testing the second CLC PSU, but with this one there is a difference between the positive and negative rail. What do you think might causes it? Different caps quoted error margin? Will the air coil affect the voltage?
The positive rail measured 33.2V
The negative rail at -29.6V
The transformer is a dual output 22-0-22 400VA
8 x MUR860 to build 2 bridges, then to C L C ; how does this affect the performance of the amp. Oh yes, this is measured without connecting to anything. Can I still use it?
The first CLC PSU measured at 34V both rails.
Any help is appreciated.
Regards,
Chris
It sounds like someting is wrong. If you use dual bridges and
everything is properly connected, the variation in capacitance
shouldn't matter when no load is connected.
Double check that both PSUs are wired in exactly the same
way.
Measure the transformer secondaries without PSU connected
(or did you use the same transformer in both cases?)
Also measure the voltages at the first cap, ie. before the choke.
If this gives no clue to the problem, post a schematic for
review of possible design errors.
everything is properly connected, the variation in capacitance
shouldn't matter when no load is connected.
Double check that both PSUs are wired in exactly the same
way.
Measure the transformer secondaries without PSU connected
(or did you use the same transformer in both cases?)
Also measure the voltages at the first cap, ie. before the choke.
If this gives no clue to the problem, post a schematic for
review of possible design errors.
They are mono block PSU, two 22-0-22 400VA transformers in different boxes.
Anyway this is how I used two multimeters to take the voltages
Xfrmer-->Bridge-->C-->L--C
At the second C there are
C+ -->A multimeter +pin
C- -->A multimeter -pin
C+ -->B multimeter -pin
C- -->B multimeter +pin
Chris
Anyway this is how I used two multimeters to take the voltages
Xfrmer-->Bridge-->C-->L--C
At the second C there are
C+ -->A multimeter +pin
C- -->A multimeter -pin
C+ -->B multimeter -pin
C- -->B multimeter +pin
Chris
OK, so start by disconnecting the PSU from the transformer and
measure the secondaries to rule out that the transformer is
faulty.
measure the secondaries to rule out that the transformer is
faulty.
AC value
Transformer is disconnected from the bridges, plug in the mains and power switched on, here is the result by measuring A/C
The Red and Yellow wire has 24.3 V
The Blue and Grey wire has 24.7 V
It is a brand new Piltron 400VA 22-0-22 potted one bought two months ago roughly. I also cut up the air coils for taking measurement again they both are at 2.84mH.
What else I can do to make the two rails same?
Regards,
Chris
Transformer is disconnected from the bridges, plug in the mains and power switched on, here is the result by measuring A/C
The Red and Yellow wire has 24.3 V
The Blue and Grey wire has 24.7 V
It is a brand new Piltron 400VA 22-0-22 potted one bought two months ago roughly. I also cut up the air coils for taking measurement again they both are at 2.84mH.
What else I can do to make the two rails same?
Regards,
Chris
chris ma said:
I am very sorry that I have caused some confusion here for I have miss quoted the -negative rail voltage it should have been typed as -32.6V the difference was 0.6V between the two rails.
Just worry it may affect amp stability
It is just all the amp schematics call for the same voltage between the +ve and -ve rails so I tried to follow. I guess I can connect this PSU to the amp box. This is my first unregulated PSU so I have no clue.
Chris
It is just all the amp schematics call for the same voltage between the +ve and -ve rails so I tried to follow. I guess I can connect this PSU to the amp box. This is my first unregulated PSU so I have no clue.
Chris
Yeah I guess it is the transformer if I use the 1.4 times rule
24.3 x 1.4 = 34.02
24.7 x 1.4 = 34.58
I measured 32.6 and 33.2
Chris.
PS:
Can I assume that one coil used up 1.38V and the other 1.42V hence the lower measured voltage?
24.3 x 1.4 = 34.02
24.7 x 1.4 = 34.58
I measured 32.6 and 33.2
Chris.
PS:
Can I assume that one coil used up 1.38V and the other 1.42V hence the lower measured voltage?
Yeah...told you it was the trafo...but I dunno why the trafo has got such different voltages...anyways...I dun think it will affect your project...unless you really care about 0.6V
I was wondering if anyone has an opinion on using one larger transformer to feed all the channels instead of separate parts. Which is likely to sound better and what are the arguments pro and con each approach? I think I'm finally going to do the Aleph-X with 4 channel output and was going to use a 3KVA toroid to feed the whole thing. Capacitance will be 140mF per channel. I've been told that using a 2.2mH coil in series with each capacitor bank will reduce the ripple by a factor of 100 but if all four channels will use over 30A at maximum power which are the right kind of coils to use and how do I configure them? I can get an iron core coil made with 16ga wire which should be able to use 8A without much current loss so will four of these (one for each tap and before each capacitor bank) still provide the 2.2mH value or is there a better way to make a quiet power supply?
Search for "SOZ choke input filter" It's a thread I started but I have to add to it as I did more experiments. 2.2 Millihenries will help reduce ripple a lot on a choke input for a classs A amp. I tried it on SOZ but I still got some hum. SOZ circuit has poor power supply rejection I went for a bigger choke 30 millihenries 5 amps 60,000 uf per rail. Can not tell the amp is on. Large chokes let you get away with less capacitors and smaller transformers. But, I degress. It only worked well with very little voltage loss and cool coils, bridge and transformer when I ran the secondarys in parallel with no secondary to ground. This reduces the transformer voltage in half but increases the current. When I ran the transformer with a choke input as per Passlab's power supply design the coils got too hot even when they had the right size chokes. I do not know why one configuration worked over the other. Alephs and Aleph X have much better power supply rejection and the smaller choke should work fine. I would go with 14ga only because the cost difference between that and 16ga is not much for a small inductor. Voltage loss will be a little less too. Also do a search for "choke input" and other post will come up.
Gnomus
Thanks, that was a really good thread you pointed me to. I still have some questions about layout but I don't know where to post them.
Thanks, that was a really good thread you pointed me to. I still have some questions about layout but I don't know where to post them.
Gnomus, FEThead, Nelson Pass or anyone else with definitive reply capability 🙂
Do you have an opinion on using one larger transformer to feed all the amp channels instead of separate parts. Which is likely to sound better and what are the arguments pro and con each approach? I think I'm finally going to do the Aleph-X with 4 channel output, 16-20V rails and 2A though each FET. I was going to use a 3KVA toroid to feed the whole thing. Capacitance will be 140mF per channel. I've been told that using a 2.2mH coil in series with each capacitor bank will reduce the ripple by a factor of 100 but if all four channels will use 32A at maximum power which are the right kind of coils to use and how do I configure them? If I decide to wind them myself, which AWG should be able to pass 8A without much current loss? Does the wire need to be laminated or can standard household wire with a thin insulation be used? I'm also a little confused about the topology. Will four coils (one for each tap and before each capacitor bank) be enough or will I need 8 to do four amps because each amp needs a positive and negative rail? Will the 2.2mH value need to be higher if the rails are closer to 20V? What value should my taps be if I want to end up with 16-20V on my rails using an LC configuration? I was thinking 24V taps on the transformer would be perfect but from what I've read, alot depends upon the losses from the coils used. Please help.
Do you have an opinion on using one larger transformer to feed all the amp channels instead of separate parts. Which is likely to sound better and what are the arguments pro and con each approach? I think I'm finally going to do the Aleph-X with 4 channel output, 16-20V rails and 2A though each FET. I was going to use a 3KVA toroid to feed the whole thing. Capacitance will be 140mF per channel. I've been told that using a 2.2mH coil in series with each capacitor bank will reduce the ripple by a factor of 100 but if all four channels will use 32A at maximum power which are the right kind of coils to use and how do I configure them? If I decide to wind them myself, which AWG should be able to pass 8A without much current loss? Does the wire need to be laminated or can standard household wire with a thin insulation be used? I'm also a little confused about the topology. Will four coils (one for each tap and before each capacitor bank) be enough or will I need 8 to do four amps because each amp needs a positive and negative rail? Will the 2.2mH value need to be higher if the rails are closer to 20V? What value should my taps be if I want to end up with 16-20V on my rails using an LC configuration? I was thinking 24V taps on the transformer would be perfect but from what I've read, alot depends upon the losses from the coils used. Please help.
All your questions are complex and more than a few. I would start a new thread. Cut and paste what you have written here and title it something like "4 Channel Aleph X help". There are a lot of people who are good at working with Aleph X. I can say to reduce the size and since the Aleph X has good power supply rejection you could use a CRC filter which produces very good results(silent amp) with this circuit. Choke input is great but hard to get it to work so that you get the voltages you want.
i build all traffos i use in my amps
and i never had any problem on uneqaul rails, why? because i wind the secondaries bifilliar (two coils at the same time)....
and i never had any problem on uneqaul rails, why? because i wind the secondaries bifilliar (two coils at the same time)....
joan2
Thank you for your post. How do you measure the permeability and expected core saturation point when you build your coils? Your feedback and opinions on using multiple transformers would be useful in this other thread in light of your experience.
Thank you for your post. How do you measure the permeability and expected core saturation point when you build your coils? Your feedback and opinions on using multiple transformers would be useful in this other thread in light of your experience.
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