The longer answer
The longer answer is that the inductor is inside the feedback loop and there is no practical way this could be implemented. There is also the question of parasitics with the transformer. It could look as a very low impedance load at the switching frequencies. Note; I did say could! Most audio transformers do not behave very well at HF but this would need to be determined.
I agree with Brian, I don’t think it is a workable idea.
Roger
The longer answer is that the inductor is inside the feedback loop and there is no practical way this could be implemented. There is also the question of parasitics with the transformer. It could look as a very low impedance load at the switching frequencies. Note; I did say could! Most audio transformers do not behave very well at HF but this would need to be determined.
I agree with Brian, I don’t think it is a workable idea.
Roger
Speaking of power supplies, what do you figure the VA of the transformers need to be... my junk box is pushing me towards a configuration with 4 0-12 or 0-13 VAC trafos with an LM338 reg (4 because transformers are cheaper than diodes in this instance)
Something like this....
dave
Something like this....
dave
Attachments
Transformer questions
This configuration generally is not good unless each 1/2 of the pairs is exactly the same as the other 1/2. If one of the pair is just a little bit higher in voltage the ripple increases dramatically as well as the fact that the higher voltage one ends up with most of the load. To give you a better idea if the ripple is .1 volt peak to peak with exactly equal voltages and now one is higher by .2 volts it will take over like 90+% of the load and the ripple doubles in amplitude as well as halves in frequency. This ½ frequency means the filter capacitance is ½ as effective. We are not talking much power here but you would want way over kill on the transformers so you get better dynamic regulation. I would recommend the transformers be at least 15 watts each and to only use 2 of them. Rectify them with snubbed bridge rectifiers. Double the power rating for 2 channels, hopefully using a dual mono type setup.
Roger
This configuration generally is not good unless each 1/2 of the pairs is exactly the same as the other 1/2. If one of the pair is just a little bit higher in voltage the ripple increases dramatically as well as the fact that the higher voltage one ends up with most of the load. To give you a better idea if the ripple is .1 volt peak to peak with exactly equal voltages and now one is higher by .2 volts it will take over like 90+% of the load and the ripple doubles in amplitude as well as halves in frequency. This ½ frequency means the filter capacitance is ½ as effective. We are not talking much power here but you would want way over kill on the transformers so you get better dynamic regulation. I would recommend the transformers be at least 15 watts each and to only use 2 of them. Rectify them with snubbed bridge rectifiers. Double the power rating for 2 channels, hopefully using a dual mono type setup.
Roger
How close is close enuff?
I've probably got at least 20 each of the 13s & the 12s so i can probably get 2 pairs pretty well matched. I estimate them at 110 & 90 VA respectively (based on the 40 VA/kg rule of thumb)
dave
I've probably got at least 20 each of the 13s & the 12s so i can probably get 2 pairs pretty well matched. I estimate them at 110 & 90 VA respectively (based on the 40 VA/kg rule of thumb)
dave
Member
Joined 2002
I see a Macbook Pro 🙂 Had one.. Did you get a nice defective one like mine ?
Do you think the 10Watts of class d is good ?
Do you think the 10Watts of class d is good ?
D10.1 power
Dave,
With your transformers already being over the top this circuit will do fine. Too bad I can’t show it to you. I am having such a time with trying to do pictures of any kind. Now my scanner is giving me fits. Words will have to do!
The picture showed a drawing of a conventional power supply with a single transformer followed by a bridge rectifier and cap leading into a regulator like what you had done. The circuit was duplicated to generate the minus supply. Since the 2 supplies are completely independent you can take advantage of the fact that the + regulators are better and just swap the output connections for the – supply.
Roger
Dave,
With your transformers already being over the top this circuit will do fine. Too bad I can’t show it to you. I am having such a time with trying to do pictures of any kind. Now my scanner is giving me fits. Words will have to do!
The picture showed a drawing of a conventional power supply with a single transformer followed by a bridge rectifier and cap leading into a regulator like what you had done. The circuit was duplicated to generate the minus supply. Since the 2 supplies are completely independent you can take advantage of the fact that the + regulators are better and just swap the output connections for the – supply.
Roger
Re: D10.1 power
I use a similar configuration to power my modules. You can see the pre regulator portion of my supply in the attached picture. The transformer is 120VA with 15VAC secondaries, the full wave bridge rectifiers are 25A (way, way overkill), the bulk filter caps are 22,000uF, and the bleeder resistors are 4k or something, can't remember. But the unloaded voltage is around 23V and a couple of LT1085 regulator circuits drop that down to 12V while killing any voltage ripple.
Of course I think the 10W of class d is good!
planet10 said:
I use a similar configuration to power my modules. You can see the pre regulator portion of my supply in the attached picture. The transformer is 120VA with 15VAC secondaries, the full wave bridge rectifiers are 25A (way, way overkill), the bulk filter caps are 22,000uF, and the bleeder resistors are 4k or something, can't remember. But the unloaded voltage is around 23V and a couple of LT1085 regulator circuits drop that down to 12V while killing any voltage ripple.
That's the main reason I chose to use a full wave bridge rectifier. The ripple frequency is 120Hz with a full wave bridge rectifer. Most regulators have much better ripple rejection at that freqency as well.sx881663 said:
I would echo Roger's recommendation.sx881663 said:
I haven't had a defective Apple product yet, and I absolutely love what they've done these new notebooks. Makes me dread having to use Windows at work...jleaman said:
Of course I think the 10W of class d is good!
That's the same supply I'm using and is pictured in the attachment. I didn't use snubbers though.sx881663 said:
Attachments
Power supply
Brian,
Yes exactly except Dave’s set up will be 2 separate transformers. This will give less ground leakage and noise. Experimenting with the AC polarity can further reduce noise.
Your setup with the big transformer might be a problem in this regard as large EI core transformers are very prone to this. The primary windings are almost always wound next to the core so can capacitively couple the AC into it and on into the ground. Ever wonder why most transformers are insulated from ground when mounted? This makes the AC input polarity meaningful and important. If the winding layer closest to the core is the neutral it forms a shield of sorts and this helps. Just try it both ways for lowest residual noise on the amps output. This is another reason SMPS are better.
Roger
Brian,
Yes exactly except Dave’s set up will be 2 separate transformers. This will give less ground leakage and noise. Experimenting with the AC polarity can further reduce noise.
Your setup with the big transformer might be a problem in this regard as large EI core transformers are very prone to this. The primary windings are almost always wound next to the core so can capacitively couple the AC into it and on into the ground. Ever wonder why most transformers are insulated from ground when mounted? This makes the AC input polarity meaningful and important. If the winding layer closest to the core is the neutral it forms a shield of sorts and this helps. Just try it both ways for lowest residual noise on the amps output. This is another reason SMPS are better.
Roger
I'm using a Plitron toroidal transformer (I looked on their website and it doesn't say but I think the primary is wound closest to the core) and have it wired up per the label on the transformer itself (line to line and neutral to neutral) and have no noise issues with it. The mains filter, toroid, bridges, filter caps, and bleeder resistors are all in an aluminum case connected to earth by means of the line filter and the unregulated DC comes out directly from the filter cap screw connections on 16ga wire and goes to the regulator boards.
Attachments
Raw supply
Brian,
Nice work but I wouldn't expect otherwise. Toroids have a core that is fully insulated from the chassis so aren’t as prone to the problem. They also do not have a break in their magnetic path to radiate large magnetic fields. Apparently the polarity is correct as marked, not all are! Some are not marked at all with both wires being the same color.
One suggestion, loose the line input filter! If you take one apart and actually see what your power is going through you would see why. Use a standard IEC followed by an appropriate fuse and then a .47uf quality film cap across the line. I would further recommend a .01uf cap from line and neutral to ground directly on the IEC pins. If you have room you could put one of the clamp type ferrite cores on the primary leads. I have heard a lot said about how these things hurt the sound, contrary to my experiences. If you don’t like it you can always remove it.
Roger
Brian,
Nice work but I wouldn't expect otherwise. Toroids have a core that is fully insulated from the chassis so aren’t as prone to the problem. They also do not have a break in their magnetic path to radiate large magnetic fields. Apparently the polarity is correct as marked, not all are! Some are not marked at all with both wires being the same color.
One suggestion, loose the line input filter! If you take one apart and actually see what your power is going through you would see why. Use a standard IEC followed by an appropriate fuse and then a .47uf quality film cap across the line. I would further recommend a .01uf cap from line and neutral to ground directly on the IEC pins. If you have room you could put one of the clamp type ferrite cores on the primary leads. I have heard a lot said about how these things hurt the sound, contrary to my experiences. If you don’t like it you can always remove it.
Roger
I don't think the line filter is really hurting anything but then again I've never listened to any of my amps without it in the supply. It's not a wimpy one as it was sourced from an older UPS battery back up and it has a 10A rating (I'll check when I get home) and rather beefy fuse.
I do have a couple transformers that have the same color wires so you have no idea of the polarity without some sort of testing or documentation.
I do have a couple transformers that have the same color wires so you have no idea of the polarity without some sort of testing or documentation.
Re: Re: D10.1 power
There was nothing wrong with Jason's MacBook Pro. He just odjected to the heat coming off the bottom. It talked to one of my techs and he said that it is not substantially more than coming off the bottom of a G4.
BTW: i did my 1st install of Parallels on a MacBook last week -- if you have to run Windows this is certainly the way to do it. With Macs now running Windows as quick as (Boot Camp) or almost as quick but way more convienently (Parallels) there is little point in getting anything but a Mac for general purpose work (and don't throw price at me -- a similarily configured Dell was a couple hundred dollars more than the MacBook)
dave
BWRX said:
There was nothing wrong with Jason's MacBook Pro. He just odjected to the heat coming off the bottom. It talked to one of my techs and he said that it is not substantially more than coming off the bottom of a G4.
BTW: i did my 1st install of Parallels on a MacBook last week -- if you have to run Windows this is certainly the way to do it. With Macs now running Windows as quick as (Boot Camp) or almost as quick but way more convienently (Parallels) there is little point in getting anything but a Mac for general purpose work (and don't throw price at me -- a similarily configured Dell was a couple hundred dollars more than the MacBook)
dave
Member
Joined 2002
Re: Re: Re: D10.1 power
Excuse me. I beg to differ.. The screen made more noise than my stereo did. and a laptop that gets hotter than a cup of coffee is retarded. BUT now they are alot colder like half the heat.
planet10 said:
Excuse me. I beg to differ.. The screen made more noise than my stereo did. and a laptop that gets hotter than a cup of coffee is retarded. BUT now they are alot colder like half the heat.
Re: Re: Re: Re: D10.1 power
Yet you sold it instead of taking it in and getting it fixed?
dave
jleaman said:
Yet you sold it instead of taking it in and getting it fixed?
dave
Member
Joined 2002
Re: Re: Re: Re: Re: D10.1 power
She got it fixed from apple in edmonton. Then 2 days later it got stolen from her car 🙁
planet10 said:
She got it fixed from apple in edmonton. Then 2 days later it got stolen from her car 🙁
Re: Re: Re: Re: D10.1 power
Anyway, that's enough about computers in my amp thread!
The case gets a bit warmer than the previous G4s (I had a PowerBook) when doing processor intensive stuff like video encoding or editing. When doing normal stuff it seems to be about the same as a G4 but the fan never comes on with the new MacBooks like it did with my PowerBook.planet10 said:
I'm not putting Windows on my hard drive because I wouldn't want it to corrupt the OS X partition 😉 I gave my girlfriend my 3 year old PowerBook G4 for her HP notebook that had multiple hardware problems. The HD was bad, the power connector needs to be replaced, and a couple keys are dead but otherwise it will work fine for running stuff like switchercad, etc.planet10 said:
When I have the AC adapter connected to the computer I can hear a high pitched whine that really pisses me off sometimes. It's clearly coming from the switching supply and other electronics inside the computer but not much I can do about it. Everything else about the computer is great.jleaman said:
Anyway, that's enough about computers in my amp thread!
Re: Re: Re: Re: Re: D10.1 power
Yeah!
BWRX said:that's enough about computers in my amp thread!
Yeah!
They are pretty. I wonder if they would be useful for Passive Line Level LCR XOs? (PLLLCRXO -- quite a mouthful)
Do you have a link to data on the family?
dave
Do you have a link to data on the family?
dave
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