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Premium ACA with CapMX PSU

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Rudi_Ratlos

Rudi_Ratlos

Member
Joined 2009
Raj, I would not use the BD639 (or did you mean the BC639)?

First: the package of the BD is TO-126, whereas the package of the BC is TO-92. The ACA PCB requires TO-92 package.
Second: the Hfe of the ZTX450 is about 170 (this is what I measured this morning in a group of 10 pcs. of ZTX450).
The Hfe of BD639 depends on the DC current gain.

Also have a look at this thread:

ZTX450 Alternative from the BC... range?

The BC639 would do it!

Regards - Rudi
 
Rudi_Ratlos

Rudi_Ratlos

Member
Joined 2009
Gentlemen, I will of course order a small couple of PCBs - in case that there is some request.
Leave your interest (your forum's nickname, how many PCBs) in this thread, please.
I will wait a week, until I will order.

You know its price: a pair of ACA PCBs costs: 2 x 7.50€ (PCBs) + 3.70€ (shipping) + 2€ (Paypal fee) - giving a total of 21€.
Tracking your letter is an service of Deutsche Post which costs 3.50€ additionally.

There is a dash-dotted track on the PCB (will no more be there, when I order).
On the rigth side of this track: this is Nelson Pass' ACA.
On its left side: you have JasonKuetemann's "CapMultiplier PSU".

I advise you to solder the "ACA - Part" of the PCB first and use an appropriate 19-25VDC/>2A SMPS Laptop PSU (for example) as PSU first.
I have inserted VDC and GND 6.3mm Faston connectors for this purpose on the PCB.

In case "your ACA" can be adjusted (as documented) and "sounds" :
then solder Jasons's PSU - and be delighted by the sound of the ACA using a regulated linear PSU.

I am currently busy with 2 other projects that have to do with "my"ACA:

- the first one: a supplementary PCB containing: Soft_Power_On, Mute, attenuation, ...
- the second: a case for this ACA

I will tell you more about these two projects tonight (tomorrow morning)..

Best regards - Rudi_Ratlos
 

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chiily

chiily

Member
Joined 2003
roadum.org.uk
Rudi,

Is there a method of commissioning these boards? I'm just in the latter stages of building a couple of PCBs and I'm wondering what to set the trimmers to for first turn on. Any help would be greatly appreciated.

Also, what determines the value of R14? I'm going to run the amp into a pair of Quad ESL 57s, would their low impedance at high freqs be better served by a particular value of R14?

And finally, do you have anymore of those MPC resistors left over? I would be very interested in another pair of PCBs and a resistor set please...

Happy new year to all...
 
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