Banned
Joined 2002
still4given said:Hi Hugo
The Transformer has two sets of primary windings. Two red wires and two black wires. I simply hooked the two black wires together and the two red wires together. I then connected the red wires to the AC hot lead and the black wires to the AC neutral. Why don't I see any ripple on the PSU when it is not under load?
On the side of the Transformer it says
Could it be that one set is for 50Hz and the other for 60Hz? I didn't think of that.
It will work with only one red and one black hooked up, but I was afraid it would not reach full mA without all four hooked up.
Blessings, Terry
You need to tie both red's together and both blacks together.. i have these same tranny's..
J'
Banned
Joined 2002
No, I think my ammeter only goes up to 200mA. There is no doubt in my mind that I am pulling a lot of current. I started out with 4 bridges but they ran so hot I switched to two to see if that would bring it down some. Also I lost another .7V using 4 bridges.
This PSU is putting out 17.1V unloaded. It is only putting out 14.8V with the board hooked up. I must have something wrong, but it is wrong on both boards because both sides do the same thing.
I'm thinking about swapping out the 0R15 resistors for 0R22. That should bring down the heat a bit but I would still like to find out why I'm getting that big ripple.
BLessings, Terry
Banned
Joined 2002
start with one thing at a time..
Lets hook up the transformers alone then mesure the voltage..
Next let's hook up the tranny with a bridge. Mesure the voltage..
Next hook up the capacitor bank.. mesure the voltage..
Are you able to buy a cheap pos radio shack meter ? I have one just for mesuring current so if i blow it up im not out any thing.. Then i use my fluke..
J'
Lets hook up the transformers alone then mesure the voltage..
Next let's hook up the tranny with a bridge. Mesure the voltage..
Next hook up the capacitor bank.. mesure the voltage..
Are you able to buy a cheap pos radio shack meter ? I have one just for mesuring current so if i blow it up im not out any thing.. Then i use my fluke..
J'
Netlist said:
I have a CRC bank. I used two 5w 0R1 in parallel per side. So, across 0R05 I have 380mV drop each side.
jleaman said:
Transformer alone 12.85VAC
Transformer after bridge only; 11.63VDC, 5.1VAC
Transformer after bridge and cap bank; 17.25VDC
No difference in measurments before and after 0R05 resistors
Cap bank = CRC 22000uf>0,05ohm>22000 (total of 4 caps per channel)
Transformer with everything hooked up to board; 12.65VAC
after bridge; 15.37VDC
After 0R05 resistors in CRC; 14.98VDC
Terry,
With ohm's law in mind you have I=U/R or 380mV/0.05ohm=7600mA or 7.6A bias.
I can't for the best of me not understand why a 1.2KVA transformer gets hot from delivering 'only' 7.6A.
Other values look good except the 5.1VAC after the bridge.
This might be a misreading of your meter.
What's more important is the AC voltage after CRC with everything hooked up.
/Hugo
With ohm's law in mind you have I=U/R or 380mV/0.05ohm=7600mA or 7.6A bias.
I can't for the best of me not understand why a 1.2KVA transformer gets hot from delivering 'only' 7.6A.
Other values look good except the 5.1VAC after the bridge.
This might be a misreading of your meter.
What's more important is the AC voltage after CRC with everything hooked up.
/Hugo
That's 15 amps total, since Terry is running 2 channels off that transformer. Isn't the 5.1 VAC is OK, if he doesn't have any filtering - just transformer and bridge?
Terry, one more measurement request. We know the unloaded AC output of the transformer, but how about under load? How much does the tranformer AC voltage at the bridge INPUT drop with both channels running?
Terry, one more measurement request. We know the unloaded AC output of the transformer, but how about under load? How much does the tranformer AC voltage at the bridge INPUT drop with both channels running?
BobEllis said:
I showed that above. It's 12.65VAC. That's only a .2V drop over what it does with nothing connected.
Unless I'm mistaken if I take 12.85*1.414=18.16-12.85=5.32 which is only slightly higher than what I'm reading.
If I add the 11.63VDC and the 5.1VAC I get 16.73 which is pretty close to the 17.1 if you figure the loss in the bridge.
It doesn't seem to me that .2v dropp is anything to worry about but you guys would know better than me.
Blessings, Terry
This looks fine to me, except the math about adding the DC and AC voltages: "If I add the 11.63VDC and the 5.1VAC I get 16.73".
It could be right, I simply don't know.
Sure 2 X 7.6A = 15.2A but still not that much to get an overheated transfo.
What about the AC voltage after CRC?
Also did you hook up the secundaries like in post #960?
Where and how did you connect ground?
/Hugo
It could be right, I simply don't know.
Sure 2 X 7.6A = 15.2A but still not that much to get an overheated transfo.
What about the AC voltage after CRC?
Also did you hook up the secundaries like in post #960?
Where and how did you connect ground?
/Hugo
Hi Hugo,
The transformer is hooked up as if it were two seperate 12-0-12 transformers. 2 sets of wires per channel, are hooked up in series with the center two wires hooked to ground and the other two to a bridge. Full wave I think it is called. Originally I had each pair going to it's own bridge and then the output from the bridges were hooked up in a center tap configuration. This caused me to lose another .7V per channel and also seemed to run hotter so I went back to only one bridge per channel. I didn't have a scope at the time so I don't know if I would have had less ripple with the 4 bridges. I may give that a try now that I have it all torn apart again. I sure hope there isn't something wrong with this trannie. I don't see this ripple thing with any of my other amps that I checked.
Blessings, Terry
The transformer is hooked up as if it were two seperate 12-0-12 transformers. 2 sets of wires per channel, are hooked up in series with the center two wires hooked to ground and the other two to a bridge. Full wave I think it is called. Originally I had each pair going to it's own bridge and then the output from the bridges were hooked up in a center tap configuration. This caused me to lose another .7V per channel and also seemed to run hotter so I went back to only one bridge per channel. I didn't have a scope at the time so I don't know if I would have had less ripple with the 4 bridges. I may give that a try now that I have it all torn apart again. I sure hope there isn't something wrong with this trannie. I don't see this ripple thing with any of my other amps that I checked.
Blessings, Terry
Terry,
With 0R412 resistors and presumably still 7.6A bias, the voltage over these resistors would be 3.13VDC because U=R*I -> 0.412 * 7.6 = 3.132.
So the voltage drop is normal.
If you have 275mVAC after CRC, it’s quite normal to have a high ripple at the output. From the scope picture that would be 150mVAC peak to peak.
What I propose is to smooth out the PSU with more capacitance.
Ideally, another CR would be a big improvement. Remember, you can’t have too much, mine has 6 X 47.000µF in a CRCRC combination, others even have more.
The 0R412 is too high a value, as your supply drops too much, resulting in wasted heat. I’d stay with 0.05 if I were you.
Now, a rough calculation tells that one channel dissipated 250W, being 500W total. That’s less then half of the capacity of the transformer.
I never operated mine at that rate so the heat might be normal.
All by all, given the relative low operating voltage of 15V and the current being 7.6A, I think you are not into overkill if you want to drive 4ohm speakers. If that’s not the case you could lower the bias as it won’t make any difference with 8ohm speakers except perhaps a better sonic performance. You should be able to achieve this with V1, V3 instead of changing source R’s.
/Hugo
With 0R412 resistors and presumably still 7.6A bias, the voltage over these resistors would be 3.13VDC because U=R*I -> 0.412 * 7.6 = 3.132.
So the voltage drop is normal.
If you have 275mVAC after CRC, it’s quite normal to have a high ripple at the output. From the scope picture that would be 150mVAC peak to peak.
What I propose is to smooth out the PSU with more capacitance.
Ideally, another CR would be a big improvement. Remember, you can’t have too much, mine has 6 X 47.000µF in a CRCRC combination, others even have more.
The 0R412 is too high a value, as your supply drops too much, resulting in wasted heat. I’d stay with 0.05 if I were you.
Now, a rough calculation tells that one channel dissipated 250W, being 500W total. That’s less then half of the capacity of the transformer.
I never operated mine at that rate so the heat might be normal.
All by all, given the relative low operating voltage of 15V and the current being 7.6A, I think you are not into overkill if you want to drive 4ohm speakers. If that’s not the case you could lower the bias as it won’t make any difference with 8ohm speakers except perhaps a better sonic performance. You should be able to achieve this with V1, V3 instead of changing source R’s.
/Hugo
Hi Hugo,
Thanks for the encouragement and evaluation. I could add more capacitance but do the caps have to be identical to the ones I've used? I bought a 10 pack so I only have two extra. I do have some 80V, 15,000uf caps I could use. Also, I didn't use any caps across the bridges. I see this done a lot. Would that help things at all?
What is the result of having ripple on the power supply? Does it affect the sound? Cause heat? To be honest, I'm less that impressed with the sound of this amp. Right now, my KSA50 clone blows it away. This was the most expensive amp to build of the ones I have built and the boards were given to me. The case is huge and runs very hot. I'm sure it uses gobs of electricity as well. The sound is going to have to improve if this amp is to stay in one piece.
I will welcome any and all suggestions for getting this amp to sound like the amp everyone has talked about.
Blessings, Terry
Thanks for the encouragement and evaluation. I could add more capacitance but do the caps have to be identical to the ones I've used? I bought a 10 pack so I only have two extra. I do have some 80V, 15,000uf caps I could use. Also, I didn't use any caps across the bridges. I see this done a lot. Would that help things at all?
What is the result of having ripple on the power supply? Does it affect the sound? Cause heat? To be honest, I'm less that impressed with the sound of this amp. Right now, my KSA50 clone blows it away. This was the most expensive amp to build of the ones I have built and the boards were given to me. The case is huge and runs very hot. I'm sure it uses gobs of electricity as well. The sound is going to have to improve if this amp is to stay in one piece.
I will welcome any and all suggestions for getting this amp to sound like the amp everyone has talked about.
Blessings, Terry
Hi Terry,
an oscillating amp can´t sound very well...... You still have the problem of R1/4 being very hot wich means that you´ve got a problem here. Try to put the scope on these and see what waveform you have.
This maybe is also the cause for your transformer running hot.
Try upping the C´s in the active current source from 3n3 to 6n8 or more. Maybe the bogger input capacitance of the fets you use has an influence here.
William
an oscillating amp can´t sound very well...... You still have the problem of R1/4 being very hot wich means that you´ve got a problem here. Try to put the scope on these and see what waveform you have.
This maybe is also the cause for your transformer running hot.
Try upping the C´s in the active current source from 3n3 to 6n8 or more. Maybe the bogger input capacitance of the fets you use has an influence here.
William
Keep going Terry! I am selfishly saying that so I can learn from your troubles to a nice amp. I am looking forward to getting going on mine and the thread is teaching me something everyday. If you do give up on it (I doubt you will), you could always series your secondaries to 24+24 and build a real nice Aleph 3/6. They go together easy...but....dont give up!
P.S. sent you a message
Marc
P.S. sent you a message
Marc
Hi William,
Well, I'm not convinced that the amp is oscillating. The wave form I'm seeing is at pretty low mS. Seems pretty clear up high. I think I've just about decided to try replacing all of the 0R15 resistors with 0R22. I think I just have the bias too high. To be honest, I can't say if the transformer is heating up or just was hot because of being in that hot case for over a day. I'm pretty sure that everything in that case would have felt hot to the touch at that point. I don't like the idea of the bridges running so hot or everything else for that matter. I'm going to try swapping those out and see how it sounds. I'm told that the high current may be causing the ripple in the PSU. I tried lowering the bias using V1 & V3 but it gets unstable when you get it down low.
It could be the output devices that I used that have affected the sound. I don't know. I don't remember what I used for C9&10. I will have to look when I get home.
Hi Marc,
I got your message. Thanks for the kind offer. I may take you up on it if I can't get this to work as is. I won't quit until I get this as good as I can. That doesn't mean it will stay together after that though. It will depend on how good it sounds. I was under the impression that this X amp was supposed to sound better than the regular Aleph. Maybe that was a misconception on my behalf.
Blessings, Terry
Well, I'm not convinced that the amp is oscillating. The wave form I'm seeing is at pretty low mS. Seems pretty clear up high. I think I've just about decided to try replacing all of the 0R15 resistors with 0R22. I think I just have the bias too high. To be honest, I can't say if the transformer is heating up or just was hot because of being in that hot case for over a day. I'm pretty sure that everything in that case would have felt hot to the touch at that point. I don't like the idea of the bridges running so hot or everything else for that matter. I'm going to try swapping those out and see how it sounds. I'm told that the high current may be causing the ripple in the PSU. I tried lowering the bias using V1 & V3 but it gets unstable when you get it down low.
It could be the output devices that I used that have affected the sound. I don't know. I don't remember what I used for C9&10. I will have to look when I get home.
Hi Marc,
I got your message. Thanks for the kind offer. I may take you up on it if I can't get this to work as is. I won't quit until I get this as good as I can. That doesn't mean it will stay together after that though. It will depend on how good it sounds. I was under the impression that this X amp was supposed to sound better than the regular Aleph. Maybe that was a misconception on my behalf.
Blessings, Terry