My humble A30

[Dennis Hui]

Hi all,

I completed this about a month ago. I finally managed to borrow
a digital camera to snap a few pictures.

But first, a big thank-you to Mr. Pass for sharing with us his
wonderful designs and his tremendous support to the DIY community.
Many thanks also go the other members of diyaudio who provided much
technical guidance and inspiration. (Too many to list here!)

This is my first completed project and it has been a great learning
experience.

I stuck close to the original A30 schematics. The only significant
part substitution I made was the use of IRFP044's for the output
devices, since I already have some on hand.

The PS uses a 500VA, 2x20 transformer with four 62000uF filter caps
and the rails are at +/-25V. The heatsinks are 11x11 pieces from
the R-theta group buy. PCB's are based on Mark Finnis' designs
(Thanks Mark!) DC offsets are 35mV (R) and 25mV (L).

And yes, I did use blue LED's

Cheers,
Dennis

 

[Dennis Hui]

one from the inside...

Warning: Messy construction ahead!

 

[Dennis Hui]

...and one from the back...

I had trouble soldering the copper Cardas binding posts
so I ended up using these. (I couldn't get the solder to
flow properly. Any suggestions?)

 

[li_gangyi]

use a slightly higher wattage soldering iron..the copper somehow acts like a heatsink and draws the heat away...which might be why your solder is not flowint well...or maybe u can try tinning your wire and the binding post before actually soldering the whole thing in...

 

[macka]

Very impressive,

You have taken real pride with this project and its well engineered.

It deserves a 5 star rating *****.

Ian

 

[B.L.]

I am looking at power supply...

1. broad copper plates for lower impedance (?)
2. resistors for higher impedance (?)

inconsistency?

 

[macka]

The copper is a convenient means of a conductor for mounting on the capacitors. The resistors are the CRC filter to reduce the AC ripple.

The pics on the X Aleph thread (page 38-41) by Mr Pass of the XA 200 show a similar arrangement.

Ian

 

[li_gangyi]

any luck trying to solder the posts?? I hate to see a good amp with a lousy binding post...

 

[roddyama]

Great Job Dennis!!

How's it sound?

WRT the Cardas posts, as li_gangyi said, get a higher wattage iron and tin the solder cup at the end of the post first.

 

[li_gangyi]

I got all of them to solder well with a 50W iron which I borrowed from my Dad...I only have a 25W one...I guess it will also do the job...but with more time...

 

[Nelson Pass]

Where's the humble part? I must have missed it.

 

[JOE DIRT®]

nice work...well executed!!!

 

[li_gangyi]

it's pretty cool...and the wiring is not that messy...if I was to do it..mine wouldn't turn out half like yours..

 

[Dennis Hui]

Hello all again,

Thank you for the kind words. I'm actually
quite happy how well it turned out, considering
my lack of experience in construction matters.

I'll give the Cardas posts another try when
I can locate a higher wattage solder iron.
Thanks for the tip.

As for the sound, I find the the A30 to be
very musical. Compared to my previous amp
(Hafler 9300), music on the A30 seems to be more
3-dimensional, with greater clarity and delicacy
in the midrange and treble . The bass is
perhaps more plump, but not unpleasantly so.

Yup, I like this amp. And as winter approaches,
the A30 also doubles as a small space heater.

Cheers,
Dennis

 

[Nelson Pass]

Yes, and plump bottom is very appropriate for the holidays.

 

[Peter Daniel]

As to attaching wires to Cardas posts, you could tap the holes and use small screws with washers to attach your wires. Actually this might be better than soldering You know, they way it's done in AC receptacles.

 

[li_gangyi]

hmmm...good idea..it's also easy to take it out oif needed...but then u have to get a tap and make sure u centre it right...I'll try it the next time I use one...but I think soldering is the easier way...