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Technik => Tech-Talk Mesa Boogie => Thema gestartet von: sermac am 29.04.2006 00:33

Titel: power transformer for dual recto
Beitrag von: sermac am 29.04.2006 00:33

Hi all !!!

I've got a question and perhapes a problem :  Huh
I want to build a dual recto and for that, I bought a transformer on TT.de : hammond 373BX
Is it ok ? I'm afraid about the current ... some one told me it is good only for 50 W, in which case I'm in a big sh**.

Which one is the best choise ?

thx in advance

Titel: Re: power transformer for dual recto
Beitrag von: sermac am 2.05.2006 20:45

does anybody built a recto or know someone who can help me

Best regards

MS

Titel: Re: power transformer for dual recto
Beitrag von: Chryz am 2.05.2006 21:23

Hey,
I´m still planing  ;) but I guess I´ll take the 372JX. It got only 300V but more current and stronger 2nd and 3rd filaments.
TubeLeo used the 373BX for his recto, perhaps ask him.
http://www.tube-town.de/ttforum/index.php?topic=1056.msg6153

Killigrew and some others used the 372JX.
By the way: which choke will you use?
mfg

Chryz

Titel: Re: power transformer for dual recto
Beitrag von: Hannes am 3.05.2006 21:28

Hi everybody!

Both Hammond xformer can't supply enough current for two 5U4 rectifiers. If you plan using the EL34s in your amp, the filament supply of the 373BX is too weak. If only hammond is an option take the 373BX despite its weaker filament supply: The sound is heavily influenced by anode voltages and this transformer is a better fit, but the maximum power delivered by the high-voltage winding ist a pretty tight fit.

Maybe take a look at the 177VA and 340VA TT toroidials.

Best regards,
Hannes

Titel: Re: power transformer for dual recto
Beitrag von: Chryz am 4.05.2006 09:45

Hey all,
5U4 what´s that???  ;)
I´ll only use the diodes. The 5V for LED´s and Switching and the 6,3V for filament. I guess I´ll add a second trafo (12AC > 6,3VDC) for the five ECC´s, so I can change from 6L6 to EL34.

@Hannes: Does ist really matter that much if the trafo got 300V or 350V? How is the sound influenced?
By the way: where can I find elkos with 600V?
Have a nice day!
mfg

Chryz

Titel: Re: power transformer for dual recto
Beitrag von: Hannes am 4.05.2006 22:19

Hello!

So you won't be using the 5U4s? It's saving you 30W - and if you don't like their effect on the sound it seems to be a good idea.

Lower voltages on the plates are said to make the sound muddier, they  yield lower output of the power amp for sure. I built a JCM800 preamp that had way too low voltages on the 12AX7s plates - it just sounded awful. Very muddy.

Best regards,
Hannes