By far the best idea. If output tube can tolerate low value grid leak resistor, of course.
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Hi all,
reviving this thread with some news.
about a month ago I got my pair of "limited range" OPTs, wound by Martin Mug from the Netherlands (he also wound transformers for Bas Horneman, DHT Rob), and yesterday I finally found the time to install them and have a first listen.
They are impressive 🙂 They are PP, 8k primary impedance and 4x 2R secondaries (can be configured for 2, 8, 18 and 32 ohms) - I use the 8R setting. They weigh about 2,5kg each, use a single amorph C core with two bobbins (like Lundahl).
I used a good DMM an measured 11 (eleven) ohms primary RDC, but have not measured the secondary. Calculated insertion loss (by Martin Mug) is 0,04dB - I think that is a record 🙂 Measured inductance is 9H, enough to play from 400Hz upwards.
They substitute a pair of fullrange 8k OPTs: good performance but nothing fancy. And the new ones do indeed sound better - I think it was worth it!
Now slowly looking into a pair for the tweeter amp.
reviving this thread with some news.
about a month ago I got my pair of "limited range" OPTs, wound by Martin Mug from the Netherlands (he also wound transformers for Bas Horneman, DHT Rob), and yesterday I finally found the time to install them and have a first listen.
They are impressive 🙂 They are PP, 8k primary impedance and 4x 2R secondaries (can be configured for 2, 8, 18 and 32 ohms) - I use the 8R setting. They weigh about 2,5kg each, use a single amorph C core with two bobbins (like Lundahl).
I used a good DMM an measured 11 (eleven) ohms primary RDC, but have not measured the secondary. Calculated insertion loss (by Martin Mug) is 0,04dB - I think that is a record 🙂 Measured inductance is 9H, enough to play from 400Hz upwards.
They substitute a pair of fullrange 8k OPTs: good performance but nothing fancy. And the new ones do indeed sound better - I think it was worth it!
Now slowly looking into a pair for the tweeter amp.
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