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-   -   Power transformer for Tubelab Simple SE (http://www.diyaudio.com/forums/tubelab/221022-power-transformer-tubelab-simple-se.html)

Sgrilli AD 5th October 2012 10:17 PM

Power transformer for Tubelab Simple SE
 
Hello,
Today I order a PCB Tubelab Simple SE and next steps are toward to list parts and transformers.

My choice for OPT is:
- GXSE15-8-5K-15W, single ended tube output transformer for 5K Ohms to 8 Ohms.

For power, I have two choices:
- XPWR033-120 -Power transformer for a 120V, 60Hz. line to 760V (380-0-380) at 200mA center tapped, 6.3V at 5A and 5V at 3A. US$ 59,48

- XPWR035-120 - Power transformer for a 120V, 60Hz. line to 740V (370-0-370) at 200mA center tapped, 6.3V (3.15-0-3.15) at 5A center tapped and 5V at 2A. US$ 79,88 - As stated by George on Tubelab site.

The electricity grid here in Brazil is 120V / 60Hz, but 117V is always found in actual operation.

Which of these two would be the best option for power transformer in this case?

Is the OPT mencioned a good choice?

Just to help: I intend to use KT88 and EL34.

Thank you all
Sgrilli AD

zman01 8th October 2012 05:16 PM

Sgrilli AD,

Do you plan to use a tube rectifier? In that case Tubelab recommends 5V @3A.

Tubes & Transformers

So maybe XPWR-033-120 is a better choice as it gives the 5V @3A tap.

If I recall correctly there are quite a few builders happy with the OPT mentioned above. If you are sticking to Edcor then you can also look into the bigger CXSE series the low end response should be better with the bigger OPTs.

However the bigger OPTs are heavier and might screw up international shipping options you had in mind - so please check the weight too.

BTW, I am no expert and have just got together parts for my own Tubelab SSE build. :)

Sgrilli AD 8th October 2012 08:53 PM

Hello zman01, thanks for your help!

Yes, I plan to use a tube rectifier, maybe with a 5AR4 or GZ-34 as indicated by George. These tubes works with 5V @2A. Am I right?

I'm just a little worried about the secondary (380-0-380) of the XPWR-033-120. What would be the B+ with this primary voltage?

Regarding the OPT, I have a pair of handmade fullrange speakers (Audio Nirvana Monitor - Super 8 Cast Frame) wich has a frequency response from 42 Hz to almost 20 KHz. It is expected at least 98 dB efficiency with any of cabinets projects available by David Dick, so I believe I do not need an OPT that works below 40 Hz nor has great power since the speakers has good efficiency. Am I right again?

I fully agree with you, international shipping is one of the biggest barriers to buying products, the other for us here in Brazil are import taxes.

Anyone else have any other comments?

Many thanks
Sgrilli AD

GanzerD 9th October 2012 02:29 AM

I used this setup (w/...035 PT)along with a 10H choke from Edcore and am very happy with it.
DaveG

zman01 9th October 2012 09:58 AM

Sgrili AD,

DaveG has already given a thumbs up on XPWR035-120.

Here's another one from Edcor that you might consider @ $57.33:

EDCOR - XPWR002-120

If you are building a Tubelab SE then you will probably need the choke too - you can look up the 10H Choke that DaveG has mentioned above.


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