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Old 9th July 2010, 05:01 PM   #1
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Default Power transformer for tube amp requirements

I posted a similar post on the Power Supplies forum, however I may get more information here.
I got a quotation for 2 power transformers of 420VA fore tube amps from a manufacturer in India. Their quotation is way cheaper from all others I received, including shipping cost. However, I don't know what specifications to ask the manufacturer, other than voltages and currents. Are there any specifications I should mention? How about the finish?
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Old 10th July 2010, 04:51 AM   #2
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You need to state whether each winding needs to be center-tapped.

It might be necessary to specify a range of mains voltages over which it may need to work.

I would specify an electrostatic shield.
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Old 10th July 2010, 09:18 AM   #3
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Thanks.
All the above are specified.
Anything else?
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Old 10th July 2010, 02:50 PM   #4
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You didn't mention the name of the maker. Are the transformers made to acceptable standards, (insulation between windings and isolation for your safety sake). Anything to hide ? A reputable company should provide primary details.
The reason why I ask is once I encounted a tube amp for repair and found the electrostatic screen was a dummy.-the primary and secondaries were wound bifiliar a dangerous practise !! A damaged primary won't protect the user. Don't always go for the cheapest.

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Old 10th July 2010, 03:48 PM   #5
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The manufacturer is Elent from India: Elent : CVT, Online UPS, Offline UPS, UPS Systems, Servo Controlled Voltage Stabilizers (SCVS), Indian UPS Manufacturers, UPS Exporter Electronic Enterprises, India . I know nothing about the manufacturer. His quotation was $70 per 420VA power transformer (before shipping) or $ 223.75 for 2 transformers including shipping. Other quotations were way higher, 1 was $1,347.00 for 2 transformers including shipping and the other was $1,450 for 2 transformers including shipping.
The other option I have is to order from China R-core custom transformers which will cost me $550 for 2 transformers before shipping.

Being on a very tight budget, I tend to order the transformers from Elent India.
I believe the transformers will be in accord with the specifications I'll give them, I only want to make sure to mention all the relevant specifications.
Right now, as far as I know, the specifications are: primary voltage and power rating, secondary windings voltages and current ratings and voltage insulation between the various windings.

Is there anything more I should specify, or ask for?
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Old 10th July 2010, 04:21 PM   #6
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humm
why not a good and sane tube trafo specialist ? you will use diode tube?.

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Old 10th July 2010, 04:36 PM   #7
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Thanks nicoch,
The transformer should be custom made, since AFAIK there is no shelf product with the spec I need. There will be vacuum tube diode rectifiers (2 6CJ3).
Are all the manufacturers you mention produce custom transformers?
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Old 10th July 2010, 04:47 PM   #8
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Quote:
Are all the manufacturers you mention produce custom transformers?
AE-Europe does for sure, and only custom. Very recommended!
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Old 10th July 2010, 05:00 PM   #9
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no lundhal

the reflect resistence of trafo is very important for diode but you can put a resistor...
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Old 10th July 2010, 05:04 PM   #10
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what you will build ? cheap or top one ?

http://www.freewebs.com/valvewizard/fullwave.html
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Last edited by nicoch58; 10th July 2010 at 05:11 PM.
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