I've got a pair of custom Sowter's for a Baby Huey EL84 build.
I didn't get a spec sheet, but this one looks fairly the same:
https://www.sowter.co.uk/colours/8378.pdf
There are 8 secondary wires, red/blue pairs numbered 1-4.
I'm having trouble understanding how to wire these given the drawing above.
The 1ohm and 16ohm diagrams are less relevant for me.
Ideally, I'd like both 4 and 8 ohm options, so either:
* Wire in parallel with multiple binding posts
* Or switchable via toggle switch.
Thanks for your help.
I didn't get a spec sheet, but this one looks fairly the same:
https://www.sowter.co.uk/colours/8378.pdf
There are 8 secondary wires, red/blue pairs numbered 1-4.
I'm having trouble understanding how to wire these given the drawing above.
The 1ohm and 16ohm diagrams are less relevant for me.
Ideally, I'd like both 4 and 8 ohm options, so either:
* Wire in parallel with multiple binding posts
* Or switchable via toggle switch.
Thanks for your help.
Attachments
You'd just need a DPDT switch to change winding #4 from in parallel with #3 to in series with #3.
Like this:
Like this:
Attachments
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Thanks! Always first to the rescue rayma.
Probably not anytime soon. I built a Tubelab SPP with Hammond OPT's a while back and absolutely loved it. That prompted me to try and build an end-game EL84 amp... I landed on the Baby Huey EL84 and ordered these Sowter's.
I waited over 4 months for them (if I recall) and just recently received them.
They were quite expensive... next time I may go with ISO-transformer as I believe are quite cheaper and I don't know how much performance they would give up
"I landed on the Baby Huey EL84 and ordered these Sowter's."
How so?
I've knocked on bunch of doors, but not been able to get configurable secondaries- Quick dive Sowters- but didn't find much this side of the pond...
Q-
Where did you go to order here?
Thx,
Jim
How so?
I've knocked on bunch of doors, but not been able to get configurable secondaries- Quick dive Sowters- but didn't find much this side of the pond...
Q-
Where did you go to order here?
Thx,
Jim
^^ This.. is where I'm at w/ my progressive designs in my small space^^
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oemcar,
for Sowter, I ordered directly from their site in the UK: CUSTOM OUTPUT TRANSFORMERS
The units aren't cheap and neither is shipping, so overall out came it fairly expensive.
For local options, I have to say I was quite happy with the Hammond 1650FA in the SPP. I bought those at Arrow.com. They come with 4/8/16 secondaries.
Best bargain is probably this Edcor: CXPP25-MS-8K/23%
8K to 4/8/16 secondaries with 23% screen taps
Transcendar can do any configuration but I heard they are a bit overbooked so not accepting new orders in the short term.
Jack at ElectraPrint can also do any secondary you choose...
Overall there are many options to choose from.
for Sowter, I ordered directly from their site in the UK: CUSTOM OUTPUT TRANSFORMERS
The units aren't cheap and neither is shipping, so overall out came it fairly expensive.
For local options, I have to say I was quite happy with the Hammond 1650FA in the SPP. I bought those at Arrow.com. They come with 4/8/16 secondaries.
Best bargain is probably this Edcor: CXPP25-MS-8K/23%
8K to 4/8/16 secondaries with 23% screen taps
Transcendar can do any configuration but I heard they are a bit overbooked so not accepting new orders in the short term.
Jack at ElectraPrint can also do any secondary you choose...
Overall there are many options to choose from.
Still haven't made much progress on my EL84 build with Sowters....
How should these be wired if using feedback?
With tapped secondaries, I've chosen a tap (say 8 ohm) tied it back to the PCB and tweaked the compensation cap according to it.
With the Sowters, the 4 and 8ohm will be switchable through a DPDT switch, there isn't a "fixed" secondary that I can tie back for tweaking the feedback.
What is the best approach?
How should these be wired if using feedback?
With tapped secondaries, I've chosen a tap (say 8 ohm) tied it back to the PCB and tweaked the compensation cap according to it.
With the Sowters, the 4 and 8ohm will be switchable through a DPDT switch, there isn't a "fixed" secondary that I can tie back for tweaking the feedback.
What is the best approach?
Attachments
Hello again,
I ended up using Hammond 1620's for my dual output strategy. 4 ohm tap goes to dedicated DVC subs w/ shunt caps- Fc of 300hz. The 8 ohm tap goes to mid's and tweets- and has full upper end range without having to scrounge from shunted sub drive. Could series coil been used for low pass instead of shunt cap? Probably, but then attenuation of bass response due to increased Z would result, IMO.
Anyway-
To your point about feedback connection point; I used 8 ohm tap for feedback loop. My thinking is if you have switchable 4/8 ohm capability, then you may have to assign different feedback R values for each config. So maybe 3PDT would be remedy?
Jim
I ended up using Hammond 1620's for my dual output strategy. 4 ohm tap goes to dedicated DVC subs w/ shunt caps- Fc of 300hz. The 8 ohm tap goes to mid's and tweets- and has full upper end range without having to scrounge from shunted sub drive. Could series coil been used for low pass instead of shunt cap? Probably, but then attenuation of bass response due to increased Z would result, IMO.
Anyway-
To your point about feedback connection point; I used 8 ohm tap for feedback loop. My thinking is if you have switchable 4/8 ohm capability, then you may have to assign different feedback R values for each config. So maybe 3PDT would be remedy?
Jim
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There is a tap that's allways 4Ω you can use for a (to 4Ω adapted) feedback.
And 1+1 gives 4Ω (1+1)², 1+1+1+1 gives 16Ω (1+1+1+1)², but 1+1+1 doesn't give you 8Ω but 9Ω (1+1+1)²
Mona
