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Loftin-White

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I've recently completed a Fi-Primer Loftin-White. Tubes are Sovtek. OPT's are Transcendar I got from e-bay; they seem to be exellent. Power transformer & choke are custom Electra-Print. I used Shottky Cree doides & later added a standby switch as turn on surge went above 500V. Voltages are within +5% except for the driver which I need to bring down some. Sound is very neutral with extended lows & highs. There's no euphonic mids, soggy bass & rolled off highs one might expect from a SE amp. Micro detail is very well defined, easily revealing double tracked vocals, ect. It's also easily driven by a CD player/passive preamp. This is my third major project, the first being a SE amp using a Svetlana 811-10. The L-W is much better sounding. The second was a EL-509 OTL which is a very nice sounding amp, but doubles a s a space heater. So far I'm very impressed with this amp. Let me know what you think.
 

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Thanks, I really like the sound of this amp. It easily drives my 90db speakers in a small room. I think the circuit designer got it right.

I found the Transcendar OPT's on e-bay by searching for "300b" There's a pair for sale every couple weeks or so. The price is on the low side & a good value. They are made in California, 3K pri., 100ma., 8 & 4 ohm sec. I measure around 268 ohm pri. dcr & they are very well matched. They have black cloth cemented around M6 lams & 18g teflon leads. Interleaving on pri. & sec.
 
Thanks, everything has its own ground wire & is star grounded to a screw near the input, except power transformer CT & C1 share a ground. For the most part signal is in one bundle & PS is in another bundle. Don't know if this is the best way to do it or not, but it works & notice no problems. The amp is very quiet & channel seperation is very good.
 
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I just purchased a pair of these transcendar transformers on eBay, very reasonably priced, ($120) and tubelab indicated that they perform very well in a large number of amplifiers he built and sold using them.
I hesitate to spend astronomical amounts of money on output transformers for most of my projects, so these grooved well with me, more so on the positive comments of others who have used them. In the past I have frequently found and recycled vintage transformers often discovering in the process that they sometimes out perform many boutique brands..

I am thinking about a 2A3 amplifier I might build with them...
 
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I'll second 5U4's design post, I have designed and built something very similar and the basic topology is very good.

The transcendar output transformers I purchased are outstanding at the price, an absolute steal. Even at twice the price I would be able to recommend them as highly. I am sure there are better transformers out there, but these seem to offer most of the performance to be had regardless of price, and at an insanely low price.
 
Probably not, my understanding is that these SE transformers are leftovers from a run for an unnamed OEM that apparently went under prior to all scheduled deliveries being made and afaik once they're gone they're gone.

That was the story that I got from Transcendar also. I was told to buy as many as I needed because there would be no more when they were gone. So I bought 20 of them. They are still for sale on Ebay. Maybe he had a lot of them. HOWEVER....

Transcendar is now selling push pull transformers on Ebay. I just looked and they have no items listed currently, but the last two sets of P-P transformers went for $90 per pair. I have not tried the P-P transformers, but the SE transformers work great. That is why I bought 20.
 
Loftin White -wonderful circuits

I agree that Loftin White amplifiers have better microdinamics and greater realistic reproduction of voices and un-amplified instruments.
I have built the two annexed amplifier:
-set EC8010-VT52-Gz32 with Lundahl 1623 transformers (5k-8ohm). It use Audio Note copper coupling capacitor, but I have tried it also with russian teflon capacitor (more cold sound).
-Loftin White kind E83CC+VT52-hexfred rectifiers-Lundahl 3k-8ohm.
I admit that the Loftin White is a lot more realistic on chamber music-jazz-voices-classical and I like it very much.
I use them on Tannoy Edinburgh HE loudspeakers 94dBW with adeguately strong sound
 

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