Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leonka on February 12, 2015, 09:10:52 am
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I need a 220v main transf. for the obj amp...how about this 220v main power? Could it be a right choice?
Thanks
Leo
http://www.hammondmfg.com/pdf/EDB291AEX.pdf (http://www.hammondmfg.com/pdf/EDB291AEX.pdf)
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Might be a tad light, I think the one recommended is 041316? 120mA and 3A heater, the one you referenced is 83mA and 2A.
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Take a look at this one
weber W025130EU (https://taweber.powweb.com/store/025130eusch.jpg)
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this one will work:
http://www.hammondmfg.com/pdf/EDB290BEX.pdf (http://www.hammondmfg.com/pdf/EDB290BEX.pdf)
-pete
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Thanks everybody....just one more question about the hammobd trans. Why the 290bex is more suitable than the 390aex for this amp when in the description it's said it is for the deluxe or deluxe reverb and the 390aex for the tweed deluxe?.... This is confounding...
Thanks again
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I didn't look up the tranny spec's but take your amps tubes, add up/calculate the current for each, the voltage you want on the PA tubes, add up the heater current draw, then add 50% fudge factor n you're close to what you want. Also consider things like tube vs diode rectification, whether you want supply sag.
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I need a 220v main transf. for the obj amp...how about this 220v main power? Could it be a right choice?
Thanks
Leo
http://www.hammondmfg.com/pdf/EDB291AEX.pdf (http://www.hammondmfg.com/pdf/EDB291AEX.pdf)
That transformer should be OK for a stock 5E3.
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tweed chassis hoffman sells i assume is the mojotone: the cutout is for 290BEX: hole centers are 2-7/8" x 2-1/4". the 20AEX is 2-1/2" x 2" mounting centers. confirm your chassis has or what you'll purchase has for the PT cutout.
better still, doug can order the mojotone 756EX for you, as it's the correct 220V PT for the tweed deluxe chassis.
--pete
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120mA and 3A heater, the one you referenced is 83mA and 2A.
5E3 uses a 5Y3 rectifier tube, 5v@2A heater current.
Brad :icon_biggrin:
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I can special order the Mojo transformer that Pete mentioned above
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Thanks a lot to everybody....just one more question: what do you say about this solution?
http://www.ebay.com/itm/Special-Useful-Recommended-US-to-EU-INTL-VOL-CONVERTER-240V-220V-TO-120V-110V-/171433756675 (http://www.ebay.com/itm/Special-Useful-Recommended-US-to-EU-INTL-VOL-CONVERTER-240V-220V-TO-120V-110V-/171433756675)
May it add some noise?
Could i open its plastic chassis and integrate in the amp chrome chassis?....
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Nothing to say about this?....
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Maybe kagliostro can help
He lives in Italy
I doubt anyone in the US on this forum has ever used or has a need for a device like that
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Ciao Doug
When we have to use a 110v unit we prefer to use an external transformer or an autotransformer (this last may be the more used solution)
I don't know if the converter indicated on the link will add for sure noise, but it may be; an unit like this give me more tranquility, see the link
http://www.ebay.com/itm/US-to-EU-INTL-VOLTAGE-CONVERTER-240V-220V-TO-120V-110V-Perfect-For-US-MADE-TV/171350662900?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D29310%26meid%3Df73cfd09a8c745df9ad719ca97260887%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D171433756675&rt=nc (http://www.ebay.com/itm/US-to-EU-INTL-VOLTAGE-CONVERTER-240V-220V-TO-120V-110V-Perfect-For-US-MADE-TV/171350662900?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D29310%26meid%3Df73cfd09a8c745df9ad719ca97260887%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D171433756675&rt=nc)
But often a new PT is used as substitute for the 110v standard PT present on the amp, so .......
Franco
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Yes, no doubt how better is a correct PT but now I ve got one 120v and I dont want to throw it away. I ll surely take the converter you posted....thanks a lot
A little off topic question, it s about the ground switch and how to wire it or better how to use it as a bypass switch, is it possible with the Hoffman kit curling and what is the best solution? Thanks again...
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If you are asking about adding a standby switch, just do it like it is done on the Bassman
Look here on page 2
http://el34world.com/Hoffman/files/Hoffman_5F6A.pdf (http://el34world.com/Hoffman/files/Hoffman_5F6A.pdf)
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if your 120v transformer is not rated for 50Hz and your county's power grid is 50 Hz then think about getting a transformer rated for 50Hz use.
--pete