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Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

Re: Automformers sound much superior (IMHO)

Hello, Arbelos
I use Dave Slagle's 23 step autoformers or custom made toroidal autoformers from Europe.
> What you hear might not be very much related to what you measured BTW (DC to 100 kHz linear). There are not few situations where a well designed LF roll-off is sonically superior. The same with 'good' filtering at HF, provided it is one octave above the audio range or higher. The problem with transformers is how to get a good sounding LF roll-off, an achilles heel of many transformers. Where the infrasonic bass rolls off, the core often is dangerously close to saturation or other ill effects, and the bass starts to sound bloated and / or muddy.

I agree on theory. In the real world, Dave's trafos seem to reproduce easily the lowest double bass and organ notes with no saturation. My speakers are capable of 20 Hz in-room response.

> > My experience is based on Audio Synthesis Passion, ProPassion and Passion Ultimate, EVS Ultimate 1k

I agree that if you must use resistive attenuators, try the lowest value that works in your system. 10K generally sucks.

> > It is indeed in tangibility and dynamics that higher impedance resistive att. fall short even of a rel. cheap autotransformer. But with the latter there are enough drawbacks to make it a trade-off in favour of a good res. att. – provided there is no additional line stage resolution loss and coloration which will swamp some subtle advantages of a passive res. line stage (compared to an active one). Eg. ambience retrieval, timbre informations and a sense of high transparency are the forte of a *passive* shunt attenuator 'line stage.

Agreed again. However, a really well-done autoformer will, IMO, sound much better than the simplest resistive attenuator. As you said:
> > provided there is no additional line stage resolution loss and coloration

I have found out that for CD sources my tube preamps added colorations and subtle hiss: 76 /6SN7 / 7308 battery preamp.

> > ambience retrieval, timbre informations and a sense of high transparency are the forte of a *passive* shunt attenuator 'line stage.

Ditto a good autoformer, plus lots of bass punch and no loss in dynamics.

> > Do you still use an active line stage behind the autotransformer?

No, I felt that even the most linear tubes were getting in the way of the music. Ella sounds purer without the extra gain stage.
I bought a tubed output CD player to get back some of the magic tube sound without adding hiss or distortion (see my system). A line stage's hiss is constant, it does not depend on volume setting.
OTOH a CDP's hiss is not audible unless you crank the volume to 10...which I never do anyway.
I hope this helps
Carlos




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