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Output Transformers for SSE


2010-12-28 10:13 am
While I'm waiting for my SSE board to arrive, I've been looking into the parts I need to buy. I'd like to use KT88 valves and quite fancy using Lundahl transformers. (One of the reasons for wanting to try Lundahl is I can buy in Europe and avoid shipping and import taxes, plus they are supposed to be VG quality.

Am I correct in saying this transfomer will work?http://www.lundahl.se/pdf/1663.pdf
it is 5K to 8ohms however it is only 8w.

Does anyone know if any other Lundahl transformers are suitable with a bit more power 15w?

I guess Ideally I'd like to find something with in the Lundahl range similar to this EDCOR - CXSE25-8-5K

I intend to use the amp with my Jordan JX92S single driver (no crossover) speakers and they do like a bit of power.

Thanks for any pointers, I'm totally new to this and finding the transformer selection and bit of a nightmare.
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2010-12-28 10:13 am
Thanks I'll have a look at Sowter,
Budget it what ever it takes to do a good job, as this is my 1st ever DIY amp project, it's just as much about the journey as it is the destination.
I had in mind approx £300 for all the transformers, (power, output and choke) However If I have to spend more to get it right then that's ok.
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Paid Member
2011-02-04 11:35 am

Sowter and Lundahl are definitely good choices.

From overseas, one source which can give you power, output, and choke is Edcor.

Transcendar (Home - Transcendar Audio Transformers) has OPTs and choke.

There are other sources like Antique Electronic Supply that will be able to provide you what you need.

If you get from single source, probably your shipping will be optimized. A pair of good OPTs should be around 10-13 lbs, a power transformer another 9-10 lbs and choke 2-4 lbs.

Not light these and you will need to consider shipping charges (+ duties, taxes if any).
I've wondered if the $100 a piece Magnequest RH (Robin Hood)-60s would be a good choice?

From the Magnequest site:

"Robin Hood Series RH-60
$99 each
5,000 ohm pri with 43% UL tap
8 and 16 ohm secondaries
60 madc unbal current capacity
30 henries of primary L
10 watts @ 45 hz (-3db low freq pwr. response)

small signal frequency response (varies a bit with source impedance) should be good from about 25 hertz to 30,000 hertz minimum.

Recommended Applications:
first example from WE for 300B
plate volts 350
grid bias -76
dc plate current 50 madc
5000 ohm load impedance
6.2 watts output
second and third HD; -30db and -45db respectively

second example from WE for 300B
plate volts 400
grid bias -87
dc plate current 60 madc
5000 ohm load impedance
8.3 watts output
second and third HD; -30db and -46db respectiv"