Sound Quality Vs. Measurements

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#11,722
Gentlemen, all that is nice and fine, but if I had to find a relatively powerful trafo (say 500 VA and over) which is NOT a toroid, I honestly wouldn't know where to start.

My problem is slightly diferent. Most local toroid manufacturers have single configuratios, meaning fixed diameter and higth, and I would very much like reduced diameter and increased heigth.

One has that choice, but only with small toroiids, 50VA only. I guess that's a popular value, but I have to investigate is the same is possible with 500 VA, which is what I need two of.

P.s. @ kamis - Hi neighbor!
 
#11,723
a.wayne said:
page 19
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Bare in mind that those are peak measurements (1kHz for 20ms bursts).

It's how e.g. a manufacturer as Rowen in Switzerland can claim a peak output power of a thousand watts and more in a 0.5 ohm load, with just a couple of power transistors.
(the number for their bridged design exceeds the SOA max current delivery of a Sanken device for 10ms, indicating that their measurements are 1ms peak output current levels. => http://www.avguide.ch/assets/testbericht/ampoffen250.jpg )

In your particular case, even the perfect PowerCube would not suffice.
 
#11,726
a.wayne said:
throwing out an FM1811
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Barrel-wound transformers are half the weight/size and manage 50% higher peak output levels, but in all other aspects they behave as regular transformers. Nice if your name is MJ, with your own sound studio, and not dead yet.

Regular folks would just pick a 2-3 times larger toroidal transformer (or a single R-core biggy per channel, instead of a 3kVA power transformer for stereo), and save plenty dollars.
Does it matter whether something weighs in at 100lb or 140 ?

(made me wonder how something can have an rms power consumption figure of 3600 watts, on a mains supply of 25A times 120V, aka 3000W ? )
 
#11,731
1audio said:
E core or R core?
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Both.

These and toroid are not nearly enough description of the device. There are a host of factors that can make a large difference in transformer performance that can't really be seen.

A toroid AC power transformer should have a strip wound core of high grade steel- M6 or better. They are usually run at a higher flux than an E-I core transformer because there is no cap and they can. Keep DC away from them because they do saturate easily with some DC on the ac line. Wound as usual with the secondary over the primary they have good coupling and bandwidth so power line noise passes easily. There are other types of toroid cores that are usually used for high frequency transformers (saturate easily at 60 Hz) or are used for common mode filters.

E-I transformers can be made from many grades of steel and typically are run at a flux level close to saturation. If you lower the flux you get a host of benefits and a much bigger price tag since your buying a lot more steel and copper. There are a raft of techniques for layering the windings for different applications and trade-offs. Don't judge them as a class from a few examples. Design and execution have a lot more to do with the results than type.

R core is the new hot option. It uses a laminated core with a trick winding bobbin scheme that allows the transformer to not have gaps in the laminations. Its a Japanese invention and not many shops are set up to make them so there is a premium. Also, typically the primary is on one leg and the secondary on another so the coupling from primary to secondary is reduced.

In my research and measurements a single power line filter won't cut it. The other components in the audio system may be serious power line noise offenders. All the boxes should be isolated. Effective power line filters are non-trivial and done poorly they just serve to couple the noise from one place to another, usually the grounding making things worse, not better. But the hash added by incorrectly applied filters often provides the missing "air" from slow electronics.
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Thx.
 
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#11,732
scott wurcer said:
Looks like what you need. I wonder what the full factory cost actually is.
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Scott, it's a fairly safe bet to assume that the factory price is 28-33% of the street price, although for the "high End", this may be as low as 15%. They have to advertise heavily, and the costs of that usually fall on the distributor and the dealers.

There may be some variations, if for example the dealer is also the importer, so there's no distributor/wholesale margins involved.

At least, that's the way it is in the "normal" world - I don't know about China, they are generally a completely different story.
 
#11,734
scott wurcer said:
Looks like what you need. I wonder what the full factory cost actually is.
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I'm working on uncle Jacco ...... 🙂 D and I , may get close, we will see, 80-85% is good enuff ... :snail:

dvv said:
Scott, it's a fairly safe bet to assume that the factory price is 28-33% of the street price, although for the "high End", this may be as low as 15%. They have to advertise heavily, and the costs of that usually fall on the distributor and the dealers.

There may be some variations, if for example the dealer is also the importer, so there's no distributor/wholesale margins involved.

At least, that's the way it is in the "normal" world - I don't know about China, they are generally a completely different story.
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Dealer cost is typically 50% of retail .......... :shhh:
 
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