I read about it somewhere that the isolation transformer should never be loaded past 20%-25% of it’s rating.
I am not sure
Isolation Transformer and Balanced Power versus PS Audio Regenerator
- Thread starter Ron Resnick
- Start date
I am not sure
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denkenseiki.co.jp
I guess the Denkenseiki Model NCT-G 30KVA is good for most audiophiles
Isolation transformers have regulation - this means the the output voltage is usually referred to full load. If we use a transformer at low load probably the voltage output will be higher. Considering its low cost, every "serious" audiophile should own a good AC voltmeter and measure his mains voltage.
Ideally an isolation transformer should have taps. If we use a toroidal transformer it is usually possible to unwind a few turns from the secondary when needed - output is commonly is the outer winding.
A 5% variation in mains voltage can significantly change sound quality - and particularly in some brands of tube equipment it affects reliability.
Ideally an isolation transformer should have taps. If we use a toroidal transformer it is usually possible to unwind a few turns from the secondary when needed - output is commonly is the outer winding.
A 5% variation in mains voltage can significantly change sound quality - and particularly in some brands of tube equipment it affects reliability.
Fluke Instruments has published a number of papers on the topic, some as long as 30 years ago (which are hard to find on the web these days). They are consistent about the 50% value. But it does not hurt to be conservative when it comes to isolation transformers.
A lot depends on if the equipment employs feedback. If it does not it will be a lot more susceptible to sound quality variation due to AC line Voltage.
Another good thing any isolation transformer should have is an electrostatic shield. That can often be more important than whatever other qualities an isolation transformer might have.
People going DIY can look for medical isolation transformers - most have such electrostatic screen because of safety and legal requirements.
That is the guidance that I follow. Exceeding roughly 30% of the rated current capacity is what results in compromised dynamics and can, as mentioned upstream, result in increased distortion.
Interesting. So if the Torus AVR16 is 16 amps, you are suggesting the average system draw of 5 amps is a good position?
That is what has been my experience across several balanced toroid and half a dozen normal and balanced EL (Topaz/MGE/Xentek/Taiyo-Yuden) transformers.
You won't electrically harm the equipment by exceeding that ratio. But soundstage will shrink in every dimension, the effortless micro- and macro-dynamics start to go away or get blurred, bass slam and broadband punch disappear, tonal body starts to get hollow, etc.
I have A/B'd this even on the same transformer. I wouldn't attempt to speak to the exact technical drivers behind it, but my observations have been incredibly consistent across 3 different US states...one on each Coast..., and now two different cities in Texas (Dallas & Houston).
I am also a huge fan of going balanced if one's transformer can support it. However, that electrically halves the capacity (i.e. 5kVA --> 2.5kVA, etc). Though, most transformers run far quieter (physically) and cooler in balanced. In addition, common mode noise is just crushed....so the strong sense of getting midnight/1am sound literally all day is even more solidified over a correctly sized xformer alone.
I have intentionally grossly over-spec'd my most recent 3 transformer purchases to accomodate balanced if I so choose. One (a 31 series Topaz .0005pF 2.5kVA) running my tube system is fat and happy without being run balanced. I'm not pulling more than 850w out of it at max current draw. Usually less than 650w (two 845 Monoblock SET amps ensure some current is drawn constantly).
The other two are much happier in balanced (both for audible hum and temperature...and sound quality). a 5.2kVA Taiyo Yuden .001pf and a 10kVA Topaz -31 series .0005pf.
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Th
Thank you. In fact, our system does register 5.2amps on the front of the Torus AVR16, and the Robert Kodas draw full power at all times anyway being pure Class A all the way to 235 watts into 4ohms. While I imagine (I am no techie) they might well draw more during peaks...it does appear we have the headroom based on your post.
You correctly observe that a pure class-A amp will still vary somewhat in current consumed. This is normal and expected.
I think you do have the headroom and am excited to hear what you think if you do go with the Torus AVR16.
IMHO, at the sound pressure level in your room when your amplifier leaves class A you are not able to discern sound quality ...
The XLFs are an efficient speaker. If you have doubts buy a 10 euro (sorry GBP ...) power meter at the supermarket and measure your amp power consumption. These devices affect sound quality surely, but are extremely useful do diagnose some mains and bias related problems.
The current draw of any class A1 circuit will be a constant up to full power. If the circuit is class A2 or A3 then there will be variable current draw.
If the circuit is A up to a certain power and then transitions to B its a class AB circuit plain and simple regardless of how much class A power might be available. If the circuit is competently designed the transition will be inaudible and unmeasurable in terms of waveform performance and won't matter if there is feedback or not.
This absolutely depends upon the power supply design and execution. I'm not talking about massive current swings here, but you likely know that few SET amp designs remain purely in A1. Even when they advertise that they do.
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