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Argus25 · 14th Feb 2019, 11:19 pm

Kalee20,

Have a look at the Samson brand driver transformer in this amplifier it is a 1 to (1.5 + 1.5). I was amazed at the frequency response of this one is basically close to flat from 50Hz to 12kHz, well in excess of any speakers at the time it was made in 1923. It actually required 560pF capacitance added to the secondary to get a flat response and eliminate a rise at 8kHz, when used with a UX112A driver valve. I never expected it would be that good. Because they were not "audiophile types" nobody seemed interested in these transformers and they sat on ebay for ages at a low price.

I can only hear to about 9kHz now, so 12Khz is plenty for me.The -3dB point for the whole amplifier is 34Hz & 13.5kHz. Samson's output choke is about 72H inductance plate to plate.

(This amplifier has a speaker impedance conversion transformer I wound on a small lathe with a primary over 70H, 4000T of 37awg wire and an input transformer I wound so I could drive it from an iPod, or a 1920's style radio)

http://worldphaco.com/uploads/UX-171...amplifier..pdf

14th Feb 2019, 11:19 pm	#7
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Transformer winding article. Kalee20, Have a look at the Samson brand driver transformer in this amplifier it is a 1 to (1.5 + 1.5). I was amazed at the frequency response of this one is basically close to flat from 50Hz to 12kHz, well in excess of any speakers at the time it was made in 1923. It actually required 560pF capacitance added to the secondary to get a flat response and eliminate a rise at 8kHz, when used with a UX112A driver valve. I never expected it would be that good. Because they were not "audiophile types" nobody seemed interested in these transformers and they sat on ebay for ages at a low price. I can only hear to about 9kHz now, so 12Khz is plenty for me.The -3dB point for the whole amplifier is 34Hz & 13.5kHz. Samson's output choke is about 72H inductance plate to plate. (This amplifier has a speaker impedance conversion transformer I wound on a small lathe with a primary over 70H, 4000T of 37awg wire and an input transformer I wound so I could drive it from an iPod, or a 1920's style radio) http://worldphaco.com/uploads/UX-171...amplifier..pdf Last edited by Argus25; 14th Feb 2019 at 11:24 pm.