rlaury

Focusrite ISA 110 toroid (orange pumpkin) transformer.
« on: December 31, 2018, 05:08:16 PM »
Anyone have information on this output transformer. I'm building some pre's
based on the 110. I think I can use other transformer with a feedback winding,
 but I want to stay as close to the Focusright design. It's a major part of the sound.

TIA
RonL
When all you have to work with is a hammer,
everything looks like a nail.


boji

Re: Focusrite ISA 110 toroid (orange pumpkin) transformer.
« Reply #1 on: December 31, 2018, 05:38:40 PM »
Aside,  I dig the mu-metal enclosure for the output tx. Those would be nice to have for other brands.
Do you have a pict of the pumpkin?  Curious to see it.

 Edit: Oh wow, nevermind!

« Last Edit: December 31, 2018, 05:46:12 PM by boji »

CJ

Re: Focusrite ISA 110 toroid (orange pumpkin) transformer.
« Reply #2 on: January 01, 2019, 01:22:31 AM »
"Hi. I found the datasheet of the vt30408 and it says 1:2+1 the +1 being the tertiary winding. Primary can take +20dBm and secondary is rated for 600ohms. That's all it says."

if somebody has an original then you could get the DCR measurements, core size, inductance at 20 Hz via current meter and voltage generator, then it would be easy to reverse as we could tell what kind of core material  by the permeabillity calcs.

the illusive magic pumpkin, almost as mysterious as the Peerless S-217-D but not quite,

looks like control of unbalanced DC would be important with the torroid design,

do not know why they went this route, an EI core laced 5 x 5 would seem like a wiser choice as to avoid saturation and core magnetization,



« Last Edit: January 01, 2019, 02:30:24 AM by CJ »
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

rlaury

Re: Focusrite ISA 110 toroid (orange pumpkin) transformer.
« Reply #3 on: January 01, 2019, 03:59:32 PM »
I think I may go rent one of the 500 series modules and
blueprint the transformer.

 I would think the API 2503
transformer could be made to work.
any thoughts?
When all you have to work with is a hammer,
everything looks like a nail.

CJ

Re: Focusrite ISA 110 toroid (orange pumpkin) transformer.
« Reply #4 on: January 01, 2019, 09:26:11 PM »
on paper it looks like the 2503 would work well, maybe increase the stack to 3/4" up from sq stk 5/8" to get you down to 11 K Gauss for a bit less distortion at the bottom end,

since the primary turns count is low, 287 T #30,  then amp turns are low which means the DC bias is about 600 Gauss, so total flux will be about 11.6 KG.

here are the numbers for a sq stk which will work just fine,

If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html


 

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