MikeBettinger said:
I think you're missing the loop here.
Even if the circuits' reference grounds terminate at their respective power transformer/supply references, there still exists a loop.
The loop is formed by the safety grounds and the ground conductors of the interconnects connecting the two components.
How do you not allow the current flowing through a non-zero resistance to produce a voltage drop across it?
I just look at the galvanic isolation more as a side benefit that can prevent headaches in the first place. Bottom line, I simply prefer the sound I get when using transformers in the ways that I have used them over the years.
se
Hey Mike!
Well, the output impedance is a little on the high side, but ultimately there's no reason you couldn't use a microphone step-up transformer. Though depending on how much gain you need, you might want to add a simple buffer to the trannie's output.
I have a 1:10 CineMag CMMI-10C laying around here. If you'd like, I could bring it over for you to play with.
You busy tonight?
se
hitsware said:
Well, the output impedance is a little on the high side, but ultimately there's no reason you couldn't use a microphone step-up transformer. Though depending on how much gain you need, you might want to add a simple buffer to the trannie's output.
I have a 1:10 CineMag CMMI-10C laying around here. If you'd like, I could bring it over for you to play with.
You busy tonight?
se
hitsware said:
Okie doke. EMail me your address and phone number and I'll come drop it off.
se
I would say that BandAids serve us well in case of injury. When healthy, we do not need them and do not use them, for they are a bit disturbing.
>Though depending on how much gain you need,
>you might want to add a simple buffer to the
>trannie's output.
Then I might as well just do a opamp preamp.
If it works, it will show the elegance of transformers 🙂
'Passive Gain' 🙂
>you might want to add a simple buffer to the
>trannie's output.
Then I might as well just do a opamp preamp.
If it works, it will show the elegance of transformers 🙂
'Passive Gain' 🙂
Let's get real. Audio coupling transformers are BandAids. We should avoid them if possible. 3 wire grounding can be handled without transformers.
If you need them, they can be helpful, but some people think they have special properties.
If you need them, they can be helpful, but some people think they have special properties.
>Audio coupling transformers are BandAids
If one can do a function ..
lets say 'voltage gain' ..
PASSIVELY ..
Isn't the active equivalent the BandAid ?
If one can do a function ..
lets say 'voltage gain' ..
PASSIVELY ..
Isn't the active equivalent the BandAid ?
Sorry, you seem you do not know what you speak about. There is no power gain in passive device like transformer, and it is a real issue, if you speak about "gain".
Most transformers are pretty darn bad. Most practical transformers are darn bad. And a few transformers are almost OK, and can be very useful if we have a serious RFI or ground loop problem.
For some reason, I have been making phono inputs with a gain of 10,000 at 60Hz for decades, without input or interstage transformers, AND they don't hum or pass RFI. What a concept!
For some reason, I have been making phono inputs with a gain of 10,000 at 60Hz for decades, without input or interstage transformers, AND they don't hum or pass RFI. What a concept!
PMA said:
I guess it depends on one's perspective.
I see a good quality input transformer as a very nice differential input. Are differential inputs band aids? Or how about an input that can just as readily accept input from a balanced source as an unbalanced source? Is that a band aid? Or that provides high CMRR even from unbalanced sources? Is that a band aid? Or an input that can readily flip the signal polarity of even unbalanced sources? Is that a band aid?
And what if an input which did all this, also happened, by its fundamental nature, galvanically isolated its input from its output?
Is that a band aid?
se
>Sorry, you seem you do not know what you speak about.
Me too.
>There is no power gain in passive device like transformer,
Right.
>and it is a real issue, if you speak about "gain".
Yes. But for matching one 'off the shelf' device to
another they are handy 🙂
Me too.
>There is no power gain in passive device like transformer,
Right.
>and it is a real issue, if you speak about "gain".
Yes. But for matching one 'off the shelf' device to
another they are handy 🙂
When I need a real differential input I use an instrumentation amp input configuration, just like my Sound Technology audio analyzer has. I make studio board electronics that way too. NO TRANSFORMERS, from input to output.
The late Deane Jensen promoted a pretty good, but not perfect, transformer for many designs. Why not, he made a living selling transformers.
Steve Eddy has been known to make transformer boxes and selling them to customers. Is this part of the answer? Inquiring minds need to know.
The late Deane Jensen promoted a pretty good, but not perfect, transformer for many designs. Why not, he made a living selling transformers.
Steve Eddy has been known to make transformer boxes and selling them to customers. Is this part of the answer? Inquiring minds need to know.
>He didn't say power gain. He said voltage gain.
BUT ! .... Good point ....
Real gain is power gain ...
BUT ! For practical purposes ...
Say you have a 250Ohm microphone
And a 10KOhm input to your recorder
Doesn't it make sense to use a 'matching transformer' ?
BUT ! .... Good point ....
Real gain is power gain ...
BUT ! For practical purposes ...
Say you have a 250Ohm microphone
And a 10KOhm input to your recorder
Doesn't it make sense to use a 'matching transformer' ?
john curl said:
Great. Then continue to do so. If that works for you, fine. No skin off my nose. Just don't do so while asserting that those who may prefer to use transformers and may prefer the sound they achieve when they use transformers are little more than a bunch of hearing-impaired, band aid applying morons.
What is perfect, John? And exactly what metric is used to define perfection or exactly how close to perfection you have come? And how close to perfection does something have to be perfect before it no longer matters except except as a collection of specs and measurements?
se
hitsware said:
Not necessarily. Depends on the situation. In many situations all you need is voltage gain, not power gain. Basically everything up to the loudspeakers is voltage gain.
Well, sure, when you have someone come and drop one in your lap. 😀
se
SY - my experience is that the DC offset is not much affected by a load of 1-10k.
If you can take a spectrum at different DC levels we could see what happens in the transformer.
SIgurd
If you can take a spectrum at different DC levels we could see what happens in the transformer.
SIgurd
SY said:
Steve, did I call you a "hearing-impaired, band-aid applying moron"? I don't think so. For example, when Dave Wilson made recordings, we had Deane Jensen's transformers on hand and sometimes they had to be used as a 'band-aid' to remove a ground loop or for RFI prevention. We preferred not to use the transformers (the best we could find) if we could get away without them. I have spent the last 40 years designing out transformers in audio equipment. First with pro line drivers, then with an ultra-quiet pre-preamp, then with a few studio board microphone inputs, then with a 30ips master recorder, etc, etc. Transformers used in the real world are OFTEN less than the best, because transformers are expensive and bulky, and practical manufacturers tend to skimp on them. Just look at the Neutrik NTL1. This is 'perfect sound forever'?
Pavel- thanks for taking the time to do this measurement.
Please let us know what load you have used and if we are still in class A or not?
I am looking for that 7th....
SIgurd
Please let us know what load you have used and if we are still in class A or not?
I am looking for that 7th....
SIgurd
PMA said:
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