Impedance matching the AKSA 100

Carlman · « **on:** 9 Dec 2003, 03:07 am »

If I were to obtain a pre-amp that was not an AKSA, what would the ideal impedance range to match the amp?

Is the input imp on the AKSA 47,k? Any input on things to look for would be appreciated.

I'm kind of/sort of thinking of buying a Purist to replace my Audible Illusions.... I'm really tired of playing with tubes.

Thanks for any advice,
Carl

eico1 · « **Reply #1 on:** 9 Dec 2003, 03:17 am »

It seems the lower the outut impedence the better, as long as it had adequate current capabilities and can drive high (1000pf) capacitance loads.

steve

mb · « **Reply #2 on:** 9 Dec 2003, 04:07 am »

My preamp (actually attenuator, since it has gain of ~1.0) has output impedance <10ohms. Sounds a little bit like an overkill, but it drives just about anything, and currently drives an AKSA (treble) and Rotel (bass) in tandem.

I agree -- lower is better. Of course, sound quality is the first consideration.

AKSA · « **Reply #3 on:** 9 Dec 2003, 05:24 am »

Hi Carl,

Input impedance on both AKSA amps is around 43K.

In pro audio, we talk about a bridging ratio of ten. This means anything which drives a component should have an output impedance at least ten times lower than the component's input impedance.

This means the Zout of the source should be 4K3 or lower.

Lower is better, precisely as Mervin says, because with highish impedances the cables start to have measureable impact on current delivery due to capacitive and reactive effects. So, at a pinch around 1K5 would be OK, or maybe lower still.

Most tube pres have a Zout of around 2K, which is fine. An exception is the cathode follower output, such as the GK-1, which is typically under 500R (the GK-1 is around 130R), and the transformer coupled output stage (which can be as low as 30R.)

I set the input impedance of the AKSA high so it would be easy to drive with tube pres. You can see I had tube pres in mind, can't you!!

Cheers,

Hugh

Carlman · « **Reply #4 on:** 9 Dec 2003, 03:15 pm »

Tube pre's definitely sound like a good match to the amp but, I wanted to try something different that was easy to sell if I didn't like it. However, if I get a demo of the Purist, I won't even need to worry about that.

The Purist is about $200 over my budget and I don't know if I'll really be able to do it right now but, maybe after the new year, things will change. We'll see. I think the output impedance on it is 100 ohms.

If I find a used GK-1 or abandoned project, I'd be pretty happy as well.

Thanks,
Carl

fred · « **Reply #5 on:** 9 Dec 2003, 11:53 pm »

Quote

If I find a used GK-1 or abandoned project, I'd be pretty happy as well.

What a coincidence

See:
http://www.audiocircle.com/index.php?topic=6479&sid=9e9ccdfd28531620d5bc8e057f2dc971

Carlman · « **Reply #6 on:** 10 Dec 2003, 03:02 am »

Wow! $500 is what I'm talkin' about! ... now if someone would just bite on this one...
edit... I linked to my pre which was sold... and I had deleted the post... so, this post didn't make sense.

I ended up getting a Dodd pre for $450. I'll try it out... The abandoned kit idea was good but, still more expensive than something new I could try and sell later if I didn't like. If I buy the GK-1 and make the 2-3 month commitment to building it, it better be 'the one'. So, maybe I'm postponing the inevitable.

SamL · « **Reply #7 on:** 16 Dec 2003, 01:16 am »

Um... very tempting.
Can someone comfirm that GK1EL come with universal power transformer?

Sam