Penultimate Zen - finished - photos

[Stabist]

Hi!

And finally - Zen v4 is finished.

Here are some photos of different stages in buliding process.

I hope you'll enjoy!

Thanks again to mr. Nelson; to the rest of you guys here; Sandi who build the majority of the chassis; and to Leon alias Kirc - who was my co-mate through the whole process.

The sound itself is very good, I must admit. It confirms the theory that it is not the used material what matters most but the scheme of the amp - if it's bad - the best material won't help it a lot; And if the scheme is superb - you can use ordinary stuff - and sonical results are still far better then expected ...

Altough - we do face with a small problem - when all cables ale pluged in - and when it operates - quite anoying hum can be heard in speakers - when one of the interconects is pulled out - the hum dies.

We haven't yet made ground connection between chassis and board - with the help of R20 - should we emediately do that or can it be still something else??

And also another question: speaker plugs - we've connected GND from to board to (-)/(black) speaker terminal and (-) on the board to (+)/(red) speaker terminal - SO - when using Zen v4 with ordinary preamp - the speaker cables should be crossed between amp and speaker - am I right? And when using in duet with BoZ - the cables can be connected "properly".

But - what is the difference from speaker's point of view with those two positions?? I must say that I have felling that sometimes the soundstage semms better when speakers are conected "wrong" .. So??
I bit confused about that ...

OK, enough - it's time for some photos ..

First one shows what is the base of the chassis:

[Stabist]

Then double bottom was added - on which transformer, gretz bridge and PS capacitors (3 Jamicon's - 10.000uF each) are mounted.
Then there is the 2nd floor - with boards themselves.

Somewhere on same height as between both floors - the tranzistors are mounted on the heatsink (each heatsink measures 250x145x40) and are connected to boards with cables - some silver coated Cu cables were used in that purpose - something that was found somewhere in the house ...

[Stabist]

And so does look the top floor

[Stabist]

Finished - the only thing that still ain't in place - top cover.

[Stabist]

And voila - it works - it's a bit hard to see - but the blue one "in the middle" works nicely

[Stabist]

Another top view.

[Nelson Pass]

Probably the hum is a ground loop, going from one channel
ground back to the source, and returning to the amp on
the other channel to complete the loop. Your transformer
would be inducing a current in this loop from it's magnetic
field. Lifting one of the grounds is OK, or you can put some
resistance in series with one of the grounds.

Alternatively, you can try to have both channels grounded
at some central point, and maybe play with the transformer
orientation.

pass/ - going to put on Man Ray next

[kristijan-k]

Hello Stabist,

Really excellent work !

Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip

[Stabist]

The back ain't something special - no special RCAs or speaker terminals are used - afterall - the whole amp was meant as a budget project - to demonstrate that you don't need to spend a lot of money - but still get out very good sound.

And also - Aleph5 is on it's way - Zen is just an amp that will help me wait for the A5. And what after that?? It will stay as my second amp - for tuner, tape deck, ...

[Stabist]

Another detail