Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: FREYES_7 on June 14, 2025, 03:37:27 pm
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Hello All!
I had an amp 5E3 DIY kit from amplified parts brought to me by a friend living in the US!
After all the hype, I started my new build right away, and now that is time to wire the power amp, I just realized,
The poweramp is not rated for the supply voltage in my country :sad2: :BangHead: :help:
I know I should just buy a power transformer from hammond or so, but if there's any trick that would allow me to at least check/test the amp, it will be appreciated
---EDIT---
Supply voltage here is 220V @50Hz
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Do you have any specs or documentation for the kit you could post? Sometimes transformers are made that can be wired for different primary voltages and it's just a matter of connecting the right wires in the right places.
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Do you have a 220v Variac?
Maybe run that at 120v
Or a step down transformer (rated at proper power) to reduce your 220 to 120vac
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get a 220- 125* step down transformer. - Shove it it the back of the cabinet as a permanent fixture until you get the right PT
*or whatever the wall voltage is for the PT that was supplied
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Search Hammond for the correct xfrmr. The one with your kit is likely the one in the below screen capture and only has 120V primary taps.
I used the 290BX and the below is the 240V primary version (290BEX). Although with 220V the B+ might be too low. Might be easier to do as Tubeswell suggested.
https://www.hammfg.com/files/parts/pdf/290BEX.pdf?v=1697661948 (https://www.hammfg.com/files/parts/pdf/290BEX.pdf?v=1697661948)
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Seems that Hammond designs their Europe (with "E" designation) Transformers at 240
Gemini says this:
"The core reason why Hammond designs transformers for Europe at 240V rather than 220V is due to the process of voltage standardization and harmonization within Europe.
Here's a breakdown:
Historical variations: Historically, different European countries used different mains voltage standards, including 220V in much of continental Europe and 240V in the UK.
Harmonization to 230V: The European standard now defines the nominal voltage as 230V.
Tolerance: This 230V standard allows for a tolerance range. In most of Europe (formerly 220V countries), the tolerance is 230V -10% +6% (207V to 243.8V). In the UK (formerly 240V countries), the tolerance is 230V -6% +10% (216.2V to 253.0V).
Practically, 240V is still within the acceptable range: Since 240V falls within the permissible +10% tolerance band of the 230V standard in the UK, and generally within the wider tolerance range in other parts of Europe, transformers designed for 240V are perfectly compatible with the modern European standard.
Compatibility: This allows manufacturers like Hammond to produce transformers that work across the harmonized European market, simplifying design and manufacturing.
In essence, by designing for 240V, Hammond creates a product that meets the current European standard (230V ± tolerance) and is compatible with the historically established 240V grids, particularly in the UK."
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BTW - today that 290bex seems to be $143 at Amplified Parts; at Hawk USA it is $111
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Thanks guys!
I messaged a local amp builder in the country, I think I'll rewind the transformer, if it is indeed too expensive, I will get a step transformer from 220 to 125* as suggested by tubeswell
Have a great weekend!