Hi all,
I'd like to know a few things about isolation transformers.
My gainclone's trafo is vibrating, it's not loud but noticeable when the music is at low volume. It's a mechanical vibration and it seems that it's due to DC on the power line.
I've been told that an isolation transformer will help.
But what is an isolation transformer? Does it have something special compared to a classical one, or is it simply a 1:1 trafo?
What size is needed? My gainclone is 2*60W, and uses a 225VA trafo. I'd like to place the gainclone on the isolation transformer, and if possible, the cd player too (a few VAs). Will 500VA be ok or should I look for a bigger one?
I can have a 500VA one for 40€, new. Is it a good price?
Alex
I'd like to know a few things about isolation transformers.
My gainclone's trafo is vibrating, it's not loud but noticeable when the music is at low volume. It's a mechanical vibration and it seems that it's due to DC on the power line.
I've been told that an isolation transformer will help.
But what is an isolation transformer? Does it have something special compared to a classical one, or is it simply a 1:1 trafo?
What size is needed? My gainclone is 2*60W, and uses a 225VA trafo. I'd like to place the gainclone on the isolation transformer, and if possible, the cd player too (a few VAs). Will 500VA be ok or should I look for a bigger one?
I can have a 500VA one for 40€, new. Is it a good price?
Alex
I guess I have a question as well about vibrating xfmrs. I recently bought 20 small ones and 6 of them vibrated when hooked up under noload. Since some did and some did not, I assumed that the hummers were faulty, although I didn't see how such a number could be bad. The hum was very noticeable. Faulty or not, don't think they can be used for audio anyway. The hummers did measure an off voltage, lower as I recall.
here is a link to it...it is actually quite complex with all the transformers...sorry about that......
the isolation transformer actually looks like a better option.. ;-)
http://www.diyaudio.com/forums/showthread.php?postid=191840#post191840
the isolation transformer actually looks like a better option.. ;-)
http://www.diyaudio.com/forums/showthread.php?postid=191840#post191840
The transformers have no relation to the dc blocking. You only need the two bridges and two caps. The shown ps combines dc blocking with half flux in the cores.
There seem to be 3 types of people - those who like the sound with iso tranies, those who don't and the ones that can never tell the difference
I find dc blocking to solve the problem of dc without dramatically changing the sound of the powered system - if anything i seem to prefer dc blocking soundwise. And i still haven't listened to an iso transformer i like.
analog_sa said:
The transformers have no relation to the dc blocking. You only need the two bridges and two caps. The shown ps combines dc blocking with half flux in the cores.
There seem to be 3 types of people - those who like the sound with iso tranies, those who don't and the ones that can never tell the difference
I find dc blocking to solve the problem of dc without dramatically changing the sound of the powered system - if anything i seem to prefer dc blocking soundwise. And i still haven't listened to an iso transformer i like.
did you have DC problems, or have you built this "just to be sure"?
Who doesn't? I didn't have problems to the extent that the transformers would buzz, just added tha caps to an existing non-buzzing supply and noticed a slight sonic change; not entirely positive (a bit softer bass) but pleasant enough in the midrange.
My isolation tranformers (700VA) otoh kill the dynamics big time (even on preamps). I can well imagine some listeners might prefer the dead dynamics as digital mellows down a lot and you get some of the famous 'black background'
An isolation transformer is just a 1:1 ratio. It takes the 'hash' and noise out of the transformed power that comes down your power line from the electric company. It also blocks DC but if you have DC on your AC wall power you have more to worry about than your stereo! The hum comes from some of the windings which were not done tight enough to stop the vibration, its not bad but not what you what either in a hifi setup. Mount the units with good hardware tightly and it should help.
Bricolo - yes all xfrmrs were the same. From your last post, I don't think you have a solid understanding of xfrmr operation (haaa, do any of us really?). It's true an isoxfrmr is 1:1 and removes noise, but they are usually made a bit differently than regular power xfrmrs in that the primaries & secondaries are wound in a "nonconcentric" manner (i.e. they don't overlap or interleave), therefore they have less mutual coupling which in turn doesn't conduct the signal as well (i.e. noise). Anyway, that's just one of the many aspects if isos. As far as your step-down reference goes, that kind will actually "step-down" the voltage to say,..half the value (e.g. 240v to 120v),...a different kind of beast altogether.
The xfrmrs I purchased were of the split-bobbin type, or non-concentrically wound. I purchased them for their isolation characterstics and have come to learn that is really the kind one needs for audio. Toroids are popular but are wider in bandwidth, something that can be argued against in an audio supply. And with that statement - let the rumble begin!!..) (boy oh boy, I love this place!)
The xfrmrs I purchased were of the split-bobbin type, or non-concentrically wound. I purchased them for their isolation characterstics and have come to learn that is really the kind one needs for audio. Toroids are popular but are wider in bandwidth, something that can be argued against in an audio supply. And with that statement - let the rumble begin!!..
) (boy oh boy, I love this place!)
toroid noise rejection
Maybe the best way to reject noise is to cancel it via balancing the AC on a high-bandwidth balanced transformer? The higher the bandwidth, the more high frequency noise generated before or after the transformer is cancelled? See white paper discussions on the Equi=Tech website.
I've tried (still own) lossy EI balanced isolation transformers and opposite-of-lossy high bandwidth toroid balanced isolation transformers and the latter win hands down. I mean, no contest whatever in what I heard.
Bricolo said:
Maybe the best way to reject noise is to cancel it via balancing the AC on a high-bandwidth balanced transformer? The higher the bandwidth, the more high frequency noise generated before or after the transformer is cancelled? See white paper discussions on the Equi=Tech website.
I've tried (still own) lossy EI balanced isolation transformers and opposite-of-lossy high bandwidth toroid balanced isolation transformers and the latter win hands down. I mean, no contest whatever in what I heard.
split bobbin or non concentrically wound transformers "reject" noise
Yes, they do. A further explanation would be that the interwinding capacitance is cut way down, say from several 100 pf to say 1pf, quite a reduction. It is this capacitance path that allows leakage for high freqs. Remember, caps are "shorts" at high freqs.
As for the rest of your question, I am sorry,..try as I might, I don't understand a word of it... "in out amps power supplies" has me scratching my head.
Yes, they do. A further explanation would be that the interwinding capacitance is cut way down, say from several 100 pf to say 1pf, quite a reduction. It is this capacitance path that allows leakage for high freqs. Remember, caps are "shorts" at high freqs.
As for the rest of your question, I am sorry,..try as I might, I don't understand a word of it..
. "in out amps power supplies" has me scratching my head.
sorry it was a typo
the correct sentense is
So, split bobbin or non concentrically wound transformers "reject" noise. But isn't it better to use such transformers in our amps power supplies directly, rather than a split bobbin (or non concentrically wound) isolation transformers and toroids in the amps PS?
the correct sentense is
So, split bobbin or non concentrically wound transformers "reject" noise. But isn't it better to use such transformers in our amps power supplies directly, rather than a split bobbin (or non concentrically wound) isolation transformers and toroids in the amps PS?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.