SemiSouth Donuts

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#161
First or second post? First post is about if those trafos could do SE to Bal conversion in a proper manner for me ib the Donuts inputs. They are for line splitting as you see and can be coupled for SE input/bal output even if there are no such example on the spec.

Second post was about if they should be considered to less inductive for a good signal, I had an idea of using two per channel (since I have 10 laying around), serial all primarys (2+2, SE out to gnd) and serial each 2 output coils per trafo with one end to ground. If I take signal from the opposite in each trafo I get one inverted.

I should draw but its good night story time with sonny. L8ters
 
#162
they're good enough for SE to BAL , one per channel

no need for two , if your pre can feed load presented with them secondaries loaded as per datasheet :

Optimum load for best square-wave response
(secondaries. in series):
2.8 K in series with 0.7 nF

however , considering that you are going to use them in (whole) secondary CT grounded manner , you can choose how to load it :

- without loading (observing whole amp's square waves test behavior )
-loading each half of Lundahl secondary ............ probably quarter of said R and quadruple of said C will do )
-loading entire Lundahl secondary with said RC combo , ignoring fact of CT ..... which you obviously can

that way , using one 1570 per channel , you can send all surplus ones to OPLDF

:clown:
 
#165
Thanks for an excellent answer Massa. Well 2K8 is a hefty load. Most cases would take some CF for that but then its hard to make it output 9+ V PP. Maybe some differential parafeed style with some hefty toob. 6V6 variant maybe. Salas 6V6 AF can handle some 5k I think and output the needed voltage.
 
#166
just crank up the input , with one input leg grounded

amp itself will work as SE to BAL converter

for that , 6V6 based pre will suffice , voltage wise

...... or make split load choke 6V6 (balanced , so ) preamp

..... or wait small eternity , for Brynhildr :rofl:

edit: don't call me Massa ......... call me Bwana :devily:
 
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#176
stajo said:
Cheers! Next two questions:

C4/C5 and C6/C9, what is prefered/optimal type, lyt or film?

Shall tailresistors sit tight on mosfets or can they be apart? Or rephrased, which ways in the circuit shall be held short?

:dice:
Click to expand...

C4,5 lytics
C6,9 film

no need for thermocouple of tail resistors and mosfets
as usual - keep everything shortest possible , without making short circuit

:devilr:
 
#177
Thanks. The last answer was what I thought you were gonna answer when I went to bed yesterday😀. Im at the physical planning stage, where spreading out for cooling purpouses competes with short wires.

So the R4,R7 etc, small resistors connected to bases. Is that some kind of stoppers that shall sit smack on?

Right now I am thinking to split circuit up on three perfboards, one per MOSFET with the connecting comps around them and one cooling element each.
 
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