I agree with Andrew 100%.
The silly part is what I do. I always go silly on the caps size and for that matter the transformer amp rating too! I only know when to stop adding caps and amps when I have no room left in the chassis or it has become too heavy for me to lift/work on.
I am convinced that an over sized power supply sounds better than a just right sized.
Rush
You are dreaming up problems that don't exist in my world.
In a pre-amp I always remote the transformer in a separate box and it doesn't need to be in another room, just a couple of feet away.
No noise, no interference, and much lower impedance!
I don't think Andrew was arguing this time, you made a statement that none of us could tell what you meant by.
Rush
well maybe so and yes in your application not a problem, but the problem still exists, it still creates more noise, the caps will create more current/voltage noise when charging etc if they are also oversized. its a pretty common recommendation to NOT oversize the transformer too much for low noise circuits for this reason. It can be overcome sure.
the impedance of the transformer is hardly going to be the dominant impedance in a preamp is it?
that being said I do understand the motivation/compulsion
the impedance of the transformer is hardly going to be the dominant impedance in a preamp is it?
that being said I do understand the motivation/compulsion
Yes, the impedance of the transformer is reflected.
I didn't come to this conclusion through any kind of math, I tried transformers with fatter wires in them (more current capable or another way of thinking, low impedance) and yes you can hear a difference.
Try it, buy a transformer of the same voltage as you would normally use, only 5 to 10 times the amp rating for your preamp.
You will be hooked on the silly size.
Whatever problems this creates you will work through and be glad you did.
And the caps don't hardly discharge on a preamp while your using it, so your over thinking this.
Rush
PS, Of course this is my opinion and if I am wrong, prove it by testing it, not by math or thinking about it.
No, it really isnt, the dominant impedance is that of the local regulation and decoupling, of the consumer, if you are relying on having a low impedance transformer (in another case on the end of a cable) to deal with short term local current demand in a low current, low noise circuit, youve got it backwards.
I really dont need to prove anything to you, you are the one making the claims
you are suggesting I need to replicate your preamp and power supply to prove you wrong?... lol
thats even if you assume thats my motivation...
I really dont need to prove anything to you, you are the one making the claims
you are suggesting I need to replicate your preamp and power supply to prove you wrong?... lol
thats even if you assume thats my motivation...
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Now you are thinking instead of finding out for sure.
I have done the test, I am sure.
Rush
If YOU look at where the current really flows, then you will know for sure.
Now you are just imagining where the current flows.
What is the purpose of the capacitor in your circuits?
I have no idea what your are referring to.
So you have tested a larger transformer vs a smaller one? And found what?
Are you thinking or doing?
Rush
I think before I build. I also think before I write. People these days will find any excuse to avoid thinking, it seems.
I updated my post which you may not have seen. your transformer is even in another case! assuming any transformer we are talking about has more than enough capability to power the circuit, you expect having a lower impedance larger transformer makes any difference at the end of a cable, perhaps a connector or 2, your rectifiers and smoothing/ CRC/ CLC/ or inductors? really?
no; local regulation and decoupling is supplying transient current demand, not the transformer
no; local regulation and decoupling is supplying transient current demand, not the transformer
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Hey, thats not fair changing the post after I replied.
This is just what I have found.
Please tell me, should I have not brought it up?
I surely don't want to make someone angry, it is just so easy to dismiss the idea without trying it.
So why do you bother dismissing the concept, if at least I think it sounds better?
I first found this out with a Threshold FET 10 preamp. Built power supplies for my local audio store that he then sold to his best customers with this preamp. We all had fun and it made the preamp better. Go figure!
I am not going to defend this anymore. You guys are smarter than I am, you can think all the good stuff right into your projects and you surely don't need some 60 + year old reminiscing about simple things that made a difference a long time ago.
Rush
It isn't about winning; its about do/design it yourself audio. A few people have pointed out where you should be looking/thinking about your design choices differently.
For a power amplifier with a linear supply, there is a point to a larger transformer, though in that case it is often more important to get the power supply capacitance correct and electrically close enough to the load.
For a line stage circuit with a shunt regulator, there is very little point to an oversized transformer. It is not the part of the circuit that supplies the current to a transient load.
yeah that was a bit harsh, Rush, hochopeper thought better of it too but youve quoted him already =) like I said to him, its not war, too often its easy to forget that.
I'm just saying you really need to think about the demands of the circuit locally and if theres a heap of smoothing before the regulation and then a high performance regulator; the TX impedance isnt the dominant impedance and if its not even local even moreso.
just one set of connectors and a single resistor renders the lowest impedance transformer redundant, provided the highest impedance transformer we are considering can deal with the power demands, which in a preamp are usually pretty low.
in a poweramp with very high current demands and minimal or no regulation; it becomes more important, but its still the caps that supply the current until they need filling again.
anyway i'm happy you are getting good results and you should continue to do what makes you happy, I made a single comment that turned into more than it should have. I like to have more power than needed too, but not that much and not so much in low noise circuits where it can be counterproductive.
I'm just saying you really need to think about the demands of the circuit locally and if theres a heap of smoothing before the regulation and then a high performance regulator; the TX impedance isnt the dominant impedance and if its not even local even moreso.
just one set of connectors and a single resistor renders the lowest impedance transformer redundant, provided the highest impedance transformer we are considering can deal with the power demands, which in a preamp are usually pretty low.
in a poweramp with very high current demands and minimal or no regulation; it becomes more important, but its still the caps that supply the current until they need filling again.
anyway i'm happy you are getting good results and you should continue to do what makes you happy, I made a single comment that turned into more than it should have. I like to have more power than needed too, but not that much and not so much in low noise circuits where it can be counterproductive.
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