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Multi-Way Conventional loudspeakers with crossovers

Placing autotransformer in crossover
Placing autotransformer in crossover
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Old 6th December 2018, 05:26 PM   #11
marco_gea is offline marco_gea  Italy
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Originally Posted by olsond3 View Post
Help me understand this. What known electrical properties of the autoformer make it sound different and what would make those differences better? I assume it can only have more distortion than a resistor divider if undersized (saturation, hysteresis) and some frequency response variations. Resistors could have a tiny amount of inductance, some miniscule variation with heat if undersized, self noise below 100 ohms isn't going to matter.
I don't think it's a matter of the intrinsic characteristics of the autoformer vs. the series resistor, but rather of the interaction of the attenuated tweeter with the driving amplifier.

But as I said, the differences are subtle. Not worth losing sleep over them ;-)
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Old 6th December 2018, 05:59 PM   #12
olsond3 is offline olsond3  United States
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marco_gea: You made some claims of clearly audible differences worth understanding: 1) "Best" and 2) " an autoformer-based solution just sounds a little bit better, IMHO: more dynamic, essentially, and possibly subjectively slightly more "refined", for whatever that may be worth."

If it comes down to interaction with the amplifier, I can see that could happen if it presented a higher impedance to the amplifier. Amplifiers typically have lower distortion when used with higher impedance loads (Doug Self). So the transformer when used to attenuate should present a higher impedance, unless you place an 8 ohm resistor at the input to the autotransformer, as suggested, then the load to the amplifier will look identical. I'm not seeing the mechanism for audible improvement using well understood electrical properties.
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Old 6th December 2018, 06:26 PM   #13
alayn91 is offline alayn91  France
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Hello,
And, where can this kind of auto-transformer be found ??
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Old 6th December 2018, 08:41 PM   #14
hottattoo is offline hottattoo  United States
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Send an email to Dave Slagle (Emia audio ) since he can custom wind autoformers / transformers to your specs. Good luck.
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Old 6th December 2018, 08:46 PM   #15
hottattoo is offline hottattoo  United States
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Almost forgot, Fostex makes a transformer attenuator ( model R100t ) which may also work.
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Old 7th December 2018, 05:55 AM   #16
GM is offline GM  United States
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Quote:
Originally Posted by olsond3 View Post
Help me understand this. What known electrical properties of the autoformer make it sound different and what would make those differences better?
FWIW: intact audio

GM
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Old 7th December 2018, 10:59 AM   #17
Kay Pirinha is offline Kay Pirinha  Germany
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If these advantages of an autoformer over a L-pad or a simple resistor in series can be measured or verified otherwise, the explanation might be that the tweeter sees a decreased source impedance from an autoformer, while the impedance usually is increased by resistors. No need to worry about saturation effects in the tweeter section in my opinion, as the signal Level isn't that large here ans a transformer may cope with the HF range much easier.
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Old 7th December 2018, 01:07 PM   #18
mboxler is offline mboxler  United States
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If the tweeter is 8 ohm and draws no more than 10 watts...

ALK Engineering

Click on Klipsch Loudspeaker Upgrades, then Tweeter Attenuators.
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Old 7th December 2018, 05:07 PM   #19
olsond3 is offline olsond3  United States
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Default Got it. Higher impedance presented to amplifier.

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Originally Posted by GM View Post
FWIW: intact audio

GM
Thanks for the references. So it looks like the benefit comes from putting it before the crossover so that it can present a higher impedance to the amplifier, resulting in lower amplifier output stage distortion. If I keep reading, one of these days I may actually understand what's going on!
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Old 7th December 2018, 10:21 PM   #20
Brinkman is offline Brinkman  United States
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Another source for autoformers is Bob Crites: Autotransformers | Critesspeakers.com

Mast_mutter on the auction website is yet another source
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