2. amps-preamps
  3. 1202833148

Cary 805, deHavilland or Atma-Sphere? Anyone cares

Over the weekend, I have listened extensively to the following four different amplifiers and I have decided once and for all that the SET 300B, no negative feedback is the way to go.
The four amplifiers are as follows:
Passlabs X150: very neutral, powerful yet the sound almost very sterile.
EAR 834: very musical, tube mid-range yet sound the least like live music.
YBA 2 High current, Double Transformers: very musical, soft and sound very enjoyable; yet again not like live music.
Audio Note kit one: This is a killer and provided the music is limited to vocals and chamber music. Very good mid-range with good attack and the best like live music; but not very much bass.
However, this listening session made me to want more bass with the SET.
Thinking about the Cary 805, deHavilland or Atma-sphere ?
Any comment ?
Please advice
robertwolfee

Showing 2 responses by almarg

almarg's avatar
almarg
9,670 posts
 
Using an Speltz autoformer for speaker/amp impedance matching is defeating the purpose of OTL.
From the FAQ at Zeroimpedance.com:
12) What is the difference between the ZEROs autoformer and a typical tube amplifier's transformer?

The ZEROs have a few advantages over "typical" tube amp transformers:

A) The music comes out on the same winding wire that it goes in on so the music does not have to pass from a primary winding to a secondary winding.

B) There is no DC current to contend with. When a transformer is made to accommodate a DC field, its audio transparence is compromised.

C) The impedance ratio is very small (16 ohms to 4 ohms, compared to a few thousand ohms to 4 ohms). This simply means that it is much easier to achieve things like, frequency response extremes, than with a "typical" tube amp transformer. The ZEROs sport a frequence response of 2 Hz to 2 MHz.
Regards,
-- Al
almarg's avatar
almarg
9,670 posts
 
Why doesn't Atmasphere build autoformers into their amps?
I'd expect that the main reason is that it would add cost, size, and complexity to the designs, while being unnecessary with many speakers.

Also, provisions would have to be made to allow the user to select among different impedance transformation ratios, and to bypass the autoformer altogether if high impedance speakers are being used.

Finally, having a Zero close to the speaker, as opposed to within the amplifier, helps to reduce the sonic effects of the speaker cable, since it results in the resistance and inductance of the cable being proportionately less significant in relation to the increased load impedance that is presented at the end of the cable.

Regards,
-- Al
More to discover