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In Reply to: RE: Is Vintage Iron Inherently Better Than Modern? posted by geezerrocket on November 17, 2015 at 07:17:18
OK, here's a few thoughts. A lot of the so-called "comparisons" of transformers are done in an amp. So the circuit used may have a lot to do with it. A lot of modern amps are minimizing NFB, and that changes the source impedance, which changes the interaction with speakers, as compared to a 60's amp with a lot of NFB. So that's not a valid method, just as the usual triode Vs pentode output comparison, as the source impedance changes. That's also true of SETs Vs push-pull designs - the source impedance is wildly different.
I did that myself decades ago when I compared a Dynaco ST70 to a McIntosh MC225. They actually measure pretty equally as far as power output into load resistors goes. The Mac is under-rated, the Dyna over rated and both clip at around 34-35 W/ch into 8 ohms. Testing both at 25 watts/ch, the Mac has flatter power response, owing to a larger core and less core saturation at low frequencies around 30 Hz, and because of the penta-filar windings there is a lot less leakage inductance, so the high frequency power output is a lot flatter. However, hooking both to a pair of KLH 17's, they sounded the same as they measured nearly identically from 40 Hz to 15 kHz at 25 W/ch., and that's pretty much the range of those speakers.
Jerry
Follow Ups:
I have, for a long time, suspected that the primary difference in the "sound" of amps is due to their performance at or near clipping. Of course source impedance is important too, particularly when the speaker has a complex load. I have also noticed with transistor amps, that the lower powered amps of the same design, sound better as long as they are not clipping. The number of devises in the output stage also seems to affect sound quality.
Welcome back, Jerry!
Dave
You need a known voltage supply, signal generator, scientific grade oscilloscope and a working knowledge of the formulas used that apply to transformers.
Then AFTER all that - so how does it sound in my stereo????
welcome back Jerry!!!!
I have to shoot you an email. Lottsa audio stuff happening. But good and simple stuff.
charles
No, I haven't; although I have all the instruments needed. But now that I have the tools, I no longer have the transformers. (or much interest)
Jerry
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