[John Chapman]

Hello!

A bit behind schedule but I finally wrapped up the Model TX103 MC stepup kit assembly instructions and they are online now. The instructions are accessed from the 'Model TX103 MC Stepup' page.

I am quite happy with the way they turned out and will re-do the TX102 kit pages to put them online as well soon. Since the TX103 kit does not have a lot of connections it is a good beginner kit and so I have put a lot of detail into the instruction set.

Also...

There is much confusion around Cartridge Loading so I have created 2 pages of info on this. Both pages form part of the assembly instructions but can be accessed from the Model TX103 MC stepup page directly. The first page is a 'how to' and the second page has some theory about how the load resistors  are 'connected' to the system and how the transformer ratio's affect the calculation of the load resistor values. I'll try and tune these up with more info as I get time but at least it's a start!

Many Thanks!

John Chapman
www.bentaudio.com

[hagtech]

I wired up a phono stage using TX103s on the front end set to 26dB gain.  The 1:20 ratio is an extreme impedance translation and it takes a good generator to drive.  My experiments showed that without a low enough generator impedance, there is a significant high frequency rolloff.  Luckily, most MC cartridges that like a 100 ohm loading have internal resistances far below 10 ohms.

When I tested at 50 ohms, the -3dB point was about 25kHz.  After modifying some test equipment I was able to drive with 10 ohms and got significantly better performance.  Rolloff was now at 110kHz.  Now this is in conjunction with a tube phono stage, so I'm not sure what the tru limit of this transformer is.  But in a real life application, even the 1:20 ratio can deliver superb performance.

Here's a 10kHz square wave response.



I was very impressed with this result.  Speaks very highly of the tranny.  More info at my circle.

jh

[John Chapman]

Hello!

Thanks for the post! Good info. One day I'll have to figure out how to put those pics in-line like that! I am supposed to be a 'computer guy' but those days are behind me now...

BTW - The packaged arrived and I am off to a great start!

Thanks!

John