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Old 25th May 2016, 04:38 PM   #1
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Default Unknown Toroid VA Rating

I have an old budget amp, an Ariston AX 910, which I'd like to upgrade to an LM3875 based gainclone.

I'm not sure of the power rating of its toroidal tranny. It's label indicates the following specs but no VA figure:

230V single primary
0-20V dual secondary

It has a serial or manufacturer number of ED10069-45116#2 but a Google search reveals nothing.

The power input for the amp is protected with a T2AL fuse. Based on this and its physical dimensions of 40mm height and 100mm diameter and comparing with other manufacturers datasheets, I'm guessing it is a 120VA, possibly 160VA.

Can anyone confirm that?
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Old 25th May 2016, 06:44 PM   #2
Mooly is offline Mooly  United Kingdom
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100 x 40 mm is small. I would say 100 VA max. The weight would be a good indicator as well.
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Old 25th May 2016, 07:22 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

Its a moot point whether a gainclone would be an upgrade,
but for sure bought cheap it is a great source of hardware
for building a gainclone.

Click the image to open in full size.

To me it looks like a gainclone already. I'd upgrade it.

rgds, sreten.

Last edited by sreten; 25th May 2016 at 07:33 PM.
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Old 25th May 2016, 08:40 PM   #4
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Quote:
Originally Posted by Mooly
100 x 40 mm is small. I would say 100 VA max. The weight would be a good indicator as well.
It weighs 1.4Kg. Browsing through numerous manufacturers' websites would seem to indicate it is a 120VA. I might purchase something that could provide a little more oomph.

Quote:
Originally Posted by sreten
Its a moot point whether a gainclone would be an upgrade
It is indeed a chip amp. It uses Philips TDA1514A chips. Upgraded to LM3875s would certainly be an improvement. This Ariston amp as is sounds pretty lifeless. OK for background music in the workshop but not in the least bit engaging for serious listening.
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Old 25th May 2016, 08:47 PM   #5
DPH is offline DPH  United States
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If you go about getting a new transformer, you're going to quickly find that it's more cost effective to go whole-hog in on a new design versus using bits from what you have.

120 VA for a stereo AB amp with ~25-26V rails is certainly fine for a first run. Of course, that will depend on how loud you listen.
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Old 26th May 2016, 08:52 AM   #6
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Quote:
Originally Posted by Derfnofred View Post
120 VA for a stereo AB amp with ~25-26V rails is certainly fine for a first run. Of course, that will depend on how loud you listen.
You're quite right. The sensible thing to do is upgrade the chips first while using the current tranny. I can always upgrade that at a later date if deemed necessary.
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Old 26th May 2016, 09:08 AM   #7
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by AlistairH View Post
It weighs 1.4Kg. Browsing through numerous manufacturers' websites would seem to indicate it is a 120VA. I might purchase something that could provide a little more oomph.
The weight is in 120 va territory but not perhaps the size. I think all you can safely say is that its somewhere in that area. Unless you are running continuous high power testing its of little relevance in an amp like this. Even an 80va tranny has more than enough ability to annihilate the original chips
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Old 26th May 2016, 05:19 PM   #8
AndrewT is offline AndrewT  Scotland
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I measured a pair of Clairtronic toroids last night, but forgot to post the results this morning.

100mm diam by 40mm high = 160VA
90mm diam by 40mm high = 100VA
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Old 26th May 2016, 05:38 PM   #9
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Thanks for that Andrew. As Mooly says, assuming it's in the range 100-120VA is about all I can do - unless there's an easy way to measure it that I'm unaware of.

I'll use it as is initially and see what the performance is like. Given that I'm likely to give this to my son and his living room isn't the biggest space I don't imagine it will be driven hard enough to make a difference
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