mcp6453 wrote:
Are the Op Amp Labs audio transformers any good?
http://www.opamplabs.com/products/lo...udio/t-25.html
They are inexpensive Triad transformers in nice octal cans. I don't remember
which Triad types they are, but they are still in production from Triad I
believe.
I'm particularly interested in how badly they ring. What causes an audio
transformer to ring?
If you terminate them properly and drive them from a low-Z load, they are
okay, but they are not transparent. They are certainly no worse than the
Edcor ones.
Transformers ring because of parasitic resonances caused by capacitance
between windings mixed with the series inductance of the winding. The
higher the impedance you try and get, the harder it is to keep it from
ringing. Fancy winding methods can help some.
Adding a zobel network to the secondary of the transformer can clean things
up a whole lot, but this also limits the range of impedances you can drive
with the transformer. Which is fine for input transformers where you always
have a known load.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."