[pookie]

I have recently sold all my high end equip and are rebuilding a value for money system.

I have a pair of modified Wharfedale diamond anniversaries, quote 89dB eff.  Which AKSA amplifer sounds the best?  I don't think that the speakers need more than 55 Watts but if the 100watt version is better I would buy that.

Also I have a 225VA +/- 31 VAC transformer, would I be able to use this with one of the designs?

Thank you

Pookie

[AKSA]

Hi Pookie,

If you like loud rock 'n roll and/or orchestral works, 100W is better.  If you like jazz and acoustic, 55W is fine.

Unfortunately your transformers are right in the middle!  They are down on power for the 100W, and up on voltage for the 55W.  You really need either two 160VA 25-0-25Vac toroids (55W) or two 300VA 35-0-35Vac toroids (100W), although in some areas with high mains voltage a 33-0-33Vac winding is suggested.

It is not recommended to build the 55W with higher voltage rails because it can exceed the SOAR ratings of the output devices, leading to failure.

A couple of 160VA Avel Lindbergs will cost you around $US42 apiece.  That right, gang?  

Cheers,

Hugh

[stvnharr]

I just ordered two 160VA 25-0-25 Avel Lindberg's for $35 ea plus shipping.

[pookie]

can the 100watt circuit be run with lower rails for lower power? but operate satisfactorily.

thankyou

pookie

[AKSA]

Thanks Steve.  That's not a bad price for the AVL trafos.

Pookie,  YES!  The 100W AKSA will operate fine with lower voltage rails, and delivers the sonic goods.  This is not so silly;  many modern loudspeakers have low impedance - I recently heard of a very expensive loudspeaker with 1.5R impedance   - and such loads do require high current but not a lot of voltage.  Consequently there is definitely a place for a two output pair amplifier operating off lower voltage rails than would be expected if it were driving an 8R load, and the advantage of this arrangement is much superior drive.

Robert Jones MD, of Newport Beach CA, a couple of months back built out an AKSA to 553W continuous into 1.63R.  It had four output pairs.  This was brand new to me (we Ozzies don't think as big as you guys Stateside!   ), but he reported extremely good performance with only 43V rails.  My thanks to Robert.  He gave me some very grand ideas!  

Cheers,

Hugh