About using oversized transformer
Nov 9, 2008 at 7:55 PM Thread Starter Post #1 of 51

Navyblue

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1. Would it emit less heat? Or it is just more efficient t heat dissipation?

2. Would it do more damage in the event of power surge or parts malfunctioning?
 
Nov 9, 2008 at 8:00 PM Post #2 of 51

luvdunhill

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Quote:

Originally Posted by Navyblue /img/forum/go_quote.gif
1. Would it emit less heat? Or it is just more efficient t heat dissipation?

2. Would it do more damage in the event of power surge or parts malfunctioning?



yes, the transformer my emit less heat, but the rest of your circuit may not like dealing with extra voltage. Remember, the rated voltage is at the specified output current, so if you draw less current, you have more voltage to deal with.
 
Nov 9, 2008 at 10:53 PM Post #4 of 51

amb

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A transformer's rated secondary voltage is usually "under full load" (the exception being those from Antek). The voltage will rise under no load or a lighter-than-full load.
 
Nov 10, 2008 at 1:13 AM Post #5 of 51

Navyblue

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Thanks, doesn't sound like too good a good thing.
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Nov 10, 2008 at 2:29 PM Post #6 of 51

Navyblue

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For a 3 board Beta 22, the recommended transformer is 2x30V 80VA. If I couldn't get one of those, which of these do I want?

- 2x25V 80VA
- 2x25V 100VA
- 2x55V 80VA
- 2x30V 63VA
- 2x30V 225VA

And what are the downside when compared to the recommended ones?
 
Nov 10, 2008 at 9:02 PM Post #7 of 51

amb

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The 2x25V transformers are probably inadequate to keep your supply rails in regulation if you plan to run +/-30V rails.

The 2x55V transformer will put out too much voltage (55 * 1.4142 = 77V, and that's under full load. Even higher unloaded), enough to damage the C5/C6 capacitors on the σ22 even if you change to 63V caps. Not to mention that it would make the σ22 drop some 40V to give you 30V output, and 3 β22 boards drawing a total of 600mA means that the poor power supply will have to dissipate 0.6A * 40V = 24W (12W per MOSFET). Too much heat.

You can use the 2x30Vˊ 63VA transformer, it just won't give you as much current headroom as the default 80VA one does. But it will work.

The 225VA one is needlessly large for a headphone amp. You could use it, but you'll need more chassis space for it, and the larger a transformer, the stronger the stray magnetic field it emits, which is something you'll have to deal with if you plan to put it anywhere near the amp boards (read: hum and noise).
 
Nov 11, 2008 at 12:52 AM Post #8 of 51

Navyblue

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Thanks again AMB.
smily_headphones1.gif


How about if I use a 2x55v 160va and use only one of the secondary? Would I get 55v 80va? Is 55v enough?

The 2x30v 225va is an encapsulated transformer. I intend to put it in another metal case and put the metal case in the main case and have it electrically isolated from the main case. The main case will be grounded to the signal ground and the inner case grounded to the mains ground. Do you think it will be an issue?
 
Nov 11, 2008 at 1:03 AM Post #9 of 51

FallenAngel

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You need both secondaries, a single 55V will not work.

I'm curious about how well an encapsulated transformer will work in the same chassis as a 4-channel Beta22 as well.
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Great deal on a HUGE 630VA unit here - DIYCable.com : Intro » Home » Exodus/Hypex Amps » Amp Parts »

I'll be running balanced headphones and REALLY efficient speakers (Omega Grande 6R which are said to work great off 6W or less).
 
Nov 11, 2008 at 2:45 AM Post #10 of 51

Navyblue

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How about if I use the 2x55v 80va, parallel the 2 secondaries and hook it to the board as a centre tapped transformer? Would it work like a 55v 80va? Again is 55v sufficient?

Somehow I am inclined towards the encapsulated. I'm getting a good deal on the 225va too.
smily_headphones1.gif
And on top of it, it just looks prettier than naked coils.
biggrin.gif
 
Nov 11, 2008 at 3:06 AM Post #12 of 51

pinkfloyd4ever

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AnTek Inc. - Transformers maybe the 1232? $18 plus $10 shipping if you're in the US
The one FallenAngel linked to, while way bigger than it needs to be, should def work too. I don't know your situation but the size isn't a problem, it may be cheaper than the Antek depending on diycable's shipping rates, which I can't seem to find.

There's also Plitron if you want top of the line, tho I think most who've tried Plitron, Antek, and Avel can't hear a difference (on gainclones anyway) Plus I've read that you might have to wait forever for Plitron to do another manufacturing run if they are out of the particular one you want. I think that's why it says "this product typically ships in 10 days" on their site, but apparently its way more than that if they do have to make some more.

Is shipping the problem? Where do you live?
 
Nov 11, 2008 at 3:14 AM Post #13 of 51

Navyblue

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Quote:

Originally Posted by FallenAngel /img/forum/go_quote.gif
55V AC is way too hot for regulating down to +/- 30V, as amb described above.


I don't mean throtling 2x55v to 2x30v. Does the S22 board support wiring for both 2x30v and 1x60v transformers? If so I guess I can parallel both 55v and treat it as a single 55v, which is close to a single 60v?
 
Nov 11, 2008 at 3:26 AM Post #15 of 51

Navyblue

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Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif
AnTek Inc. - Transformers maybe the 1232? $18 plus $10 shipping if you're in the US
The one FallenAngel linked to, while way bigger than it needs to be, should def work too. I don't know your situation but the size isn't a problem, it may be cheaper than the Antek depending on diycable's shipping rates, which I can't seem to find.

There's also Plitron if you want top of the line, tho I think most who've tried Plitron, Antek, and Avel can't hear a difference (on gainclones anyway) Plus I've read that you might have to wait forever for Plitron to do another manufacturing run if they are out of the particular one you want. I think that's why it says "this product typically ships in 10 days" on their site, but apparently its way more than that if they do have to make some more.

Is shipping the problem? Where do you live?



I am in Singapore. I'd like to get it locally if possible to avoid shipping such a relatively heavy item. I am more or less limited to what Farnell has to offer. But if I have to import it, so be it.

I have not checked if the dimension is an issue though. But the bigger issue is too much voltage and radiation.
 

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