Question on OPT

[MlinarS]

Hi,
Does any of you guys have any experiance with ISO(new Tango) OPT transformers specificaly XE-20S. How it sounds (bass, mids, highs, etc.)? The price for pair of this equals the price for single piece of Tamura. Is Tamura twice bether than Tango? Or this new Tango is not as good as the old Tango.

Second question: I calculated parameters for 300B output stage as follows:

First: With Va=425V,Ia=80ma andOPT 3K5 my Po=9.9W and output resistance 1.7 Ohm (into 8 Ohm)

Second: With same Va and Ia but OPT 5K0 my Po goes down to 8.1 W and output resistance also goes down to 1.05 Ohm.

All this is understandable but I don't know if this values of OR are to high (I read somewhere that it should be less than 1 ohm).

If I choose one OPT impedance over the other how will this afect the sound and performance of the amp (if at all).

Your input is highly appreciated.

Thank you.

 

[Brett]

Hi,
Does any of you guys have any experiance with ISO(new Tango) OPT transformers specificaly XE-20S. How it sounds (bass, mids, highs, etc.)? The price for pair of this equals the price for single piece of Tamura. Is Tamura twice bether than Tango? Or this new Tango is not as good as the old Tango.

No idea. Never used them.

Second question: I calculated parameters for 300B output stage as follows:

First: With Va=425V,Ia=80ma andOPT 3K5 my Po=9.9W and output resistance 1.7 Ohm (into 8 Ohm)

Second: With same Va and Ia but OPT 5K0 my Po goes down to 8.1 W and output resistance also goes down to 1.05 Ohm.

Sounds about right. Depending on the speaker used and it's implementation, a bit of output Z can be your friend.

All this is understandable but I don't know if this values of OR are to high (I read somewhere that it should be less than 1 ohm).

A < 1 ohm output Z in a non NFB SE amp is a very rare occurrence.

If I choose one OPT impedance over the other how will this afect the sound and performance of the amp (if at all).

The WE 300B datasheet and the other graphs on the site, show the power and 2H and 3H distortions for the output stage vs different loads. As for sonics, depends too much on what other factors are in the system, as well as personal preferences to give some sort of comment.
I'd go 3k5 myself.

 

[MlinarS]

Re: Re: Question on OPT

Thanks Brett for the responce,

[I'd go 3k5 myself. [/B]

I was thinking same, but I was a concerned about output resistance of 1.7 Ohm. Now from your post it seems that it is to be expected for non NFB design.

Thanks,