[ShinOBIWAN]

Hi all,

What torroid rating would be good for a 100N+ with the BMM M2010R1 as shown here:

http://www.bmm-electronics.com/Product.asp?Product_ID=3310

Note that the manual with the PSU also states:

The power (VA) of the transformer used with this circuit must be at least 1.5 times the theoretical amplifier power.

Also what rails does the AKSA 100N+ run on?

[AKSA]

Anthony,

For a 100W AKSA, I run +/-49V rails, using UFSR diodes rated each at 10A continuous.

Each toroid, one for each channel, is rated at 300VA.  This is twice the rating recommended by BMM for their excellent supplies.  This gives very good dynamics and regulation.

There are approximately 10,000uF per rail per module.

Cheers,

Hugh

[ctviggen]

Are you this shinobiwan:

http://www.duffroomcorrection.com/wiki/User:ShinOBIWAN

If so, I'd like to ask you some room correction questions one day, if I'm allowed.

[ShinOBIWAN]

Are you this shinobiwan:

http://www.duffroomcorrection.com/wiki/User:ShinOBIWAN

If so, I'd like to ask you some room correction questions one day, if I'm allowed.

That's me yes.

I like the bit about if I'm allowed

Feel free to get in touch if you want any help or advice.

[ShinOBIWAN]

Anthony,

For a 100W AKSA, I run +/-49V rails, using UFSR diodes rated each at 10A continuous.

Each toroid, one for each channel, is rated at 300VA.  This is twice the rating recommended by BMM for their excellent supplies.  This gives very good dynamics and regulation.

There are approximately 10,000uF per rail per module.

Cheers,

Hugh

Hugh,

Does that equate to 35-0-35?

[AKSA]

Hi Anthony,

Nominally yes, in practice, no.

Most mains grids are routinely overvoltage.  The US toroids are specced to 117Vac, but mostly the US grids are between 122 and 128 volts.

To be on the safe side, I specify a 33Vac secondary for the 100W AKSA.

This gives us (typically) a secondary DC voltage of 33 x 125/117 x 1.414 less rectifier losses.  This comes to around 49.8V, but often you find that the DC voltage is just over 50V.  This is the ideal voltage, where a 35Vac rating gives typically 52.8V, which is a little high.

Cheers,


Hugh

[natemil]

Thanks Hugh for your email reply.  Your reply was very detailed and helpful.  I believe this info would benefit all here.

...You need a 33-0-33Vac secondary of 300VA rating per channel, to cope with the overvoltage which routinely besets most power grids.  If you can't get the 33V secondaries, I recommend 30V, NOT 35V, as while this will cost a little power (a few small watts) the increase in current capacity is well worth having and the amp is better suited to low impedance loads.
 
This will give you around a 45V rail;  for protection reasons I never recommend going over 52V rails.
 
Avel Lindberg is the go...Their number on this item is Y236751.
 
Hope this is helpful, good luck with the build!
 
Cheers,
 
Hugh

If I understand correctly, "the lost of few watts" means that it will be ~90W/ch or 95W/ch instead of 100W/ch?

Also, with this transformer, rated @ 330VAC, 30-0-30, the amp would be better suited to play 4 or 6 ohms speakers?

Thanks again,

Doug

[AKSA]

Hi Doug,

Actually, the AKSA 100W is underrated;  with a 45V rail you should get around 97W, no less, and around 180W into 4R!

Cheers,

Hugh

[MarinRider]

The issue in the UK is that most transformers are rated for 230V and UK mains is specified as 230V +/-10% (to harmonise us with the rest of Europe)
However the reality is that UK mains is still actually 240V (i.e within spec), but can cause 230V transformers to hum and will produce higher rail voltages.

I had some transformers custom wound by Nuvotem with genuine 240V primaries. The benefit is that hum does not become audible until >250V and that the rails are the correct voltage, I have just taken some measurements:

230VAC gives 48.7V rails
238VAC (the actual mains voltage right now) gives 50.5V rails
240VAC gives 50.8V rails
250VAC gives 52.9V rails

Apologies for the shameless plug:
http://www.audiocircle.com/index.php?topic=25013