New SOZ with pictures!

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Dear Passophiles,
here is my brand new SOZ. This is my first amplifier. It has been lots of fun to build it, but quite hard from the mechanical point of
view. I work not far from Cinecitta' in Rome and I was lucky to met an harley biker whose job is to rebuild mechanical parts for broken cinematographic cameras. He helped me a lot with aluminium. Sometimes diy building helps you to make nice friends!

My design goal was a compact unit (to increase WAF) and as you can see I fitted inside a "small" box a 600 VA transformer and big
47,000 uF caps. Total weight should be over 20 kg. Caps and heatsinks are surplus stuff which put some constraints on the box design. Active devices are matched IRFP044 and power resistors are Dale RH series. I used 10 awg teflon copper wire for the power unit and 12 awg solid silver copper wire for the signal path.

The input voltage is around 23 V for about 10 W output.
The amps run quite hot, I did not measure them yet but they should be around 60 deg C. The measured DC offset is few tens of millivolts for both channels. The amps are not totally silent, but it is not bad for such a compact design. Probably I have to check the inductors, located just above the big toroid in the present layout.

Ah the sound... both rich and natural, full and detailed, and very live and dynamic!! They are wonderful partners for my diy speakers (TQWP with Fostex Fe103Z).

I wish to thank Mr Pass for his support to the DIY community
and all the forum members for so many hints and tips...

Carlo
 

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nice looking amp!!

what is the output power / rail volts?

Did you use 50W or 100W resistors?

For the size of the big cans, I bet they are 100V rated or very old.

I would try newer/smaller one just to check sound quality.

I bought some 150000uF panasonic big cans real cheap and I'm feel that some high quality 47000uF are better then this babies.

I will use them in a 15W SOZ that I'm building.
 
...i hope that's not a yellow LED on the front panel...

i'm afraid your highs will be etched and your lows tubby,
with an all around dryness/dark/bright causal effect...

a Blue LED will clear all this up though


moe29
--------
the Blue Led enforcer
:eek:

(still a great looking amp though!)
 
The importance of LED - regarding sound caracter

moe29 said:
...i hope that's not a yellow LED on the front panel...

i'm afraid your highs will be etched and your lows tubby,
with an all around dryness/dark/bright causal effect...

a Blue LED will clear all this up though


moe29
--------
the Blue Led enforcer
:eek:

(still a great looking amp though!)
Yes, That is true!
We all know by discussion, the importance of Wire Colors!

Follow up to cap sleeve thread,Wire color makes a diffrence!!
--------------------------------------

But also what solder you use & and of course the frontLED
will heavily effect the Sound of any amplifier in a substancial
and very noticeable way.

This is a well establish fact through serious listening research by
some of worlds "most golden ears".
Can not be ignored!!! :idea:

The frontal/center sounds will be most affected
by this LED - many poor guys live with bad "upfront sounds".

Thanks moe29, for pointing this out to this obvious newcomer
- who is happily unknowing of this defect of this otherwise interesting amplifier.



/halo - mixes his LEDs for the ultimate sound performance :cool:
 
PedroPO said:
nice looking amp!!

what is the output power / rail volts?

Did you use 50W or 100W resistors?

For the size of the big cans, I bet they are 100V rated or very old.

I would try newer/smaller one just to check sound quality.

I bought some 150000uF panasonic big cans real cheap and I'm feel that some high quality 47000uF are better then this babies.

I will use them in a 15W SOZ that I'm building.

Rail volts are 23 V, the tranformer secondaries are 20 V.

I used 50 W resistors for the 8 Ohm value and 25 W for the 1 Ohm.

You are right, caps are 100V rated, I will try also newer (and may be better) caps. These big caps come from a surplus store and they were very cheap.

Carlo
 
Re: What kind of speaker Cables are those?

PaulHilgeman said:
It looks like 80 pin SCSI cable... arent those usually just tinned copper? How do they sound, are the pairs twisted?

-Paul

Sorry I do not know which kind of cable it is, but I do not think it is a scsi cable.
Conductors are stranded silver copper wires, not twisted. It sounds very transparent and also very similar to cat5 that I am using now.
 
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