first DIY-amp: SOZ

[Danman]

hi,

my name is Daniel, i'm living in Austria, Vienna.
i plan to replace my old two way-speakers with a pair of fullrange-speakers with a sensivity of ~93dB.
it think speakers like this are predestined for fine a single-endet amp, best from PASS ;-)
so i want to build a SOZ. SOZ, because, after all i read here, with speakers like this, it should give a nice couple..
i know, this amp is a hot thing, so i plan a watercooling (maby a waterbed later, as accessory)

i hope it's a practicable thing, to drive the SOZ unbalanced without active pre-amp (just a poti behind CDP)
if it is, i want to build a ~10W version.

* my first problem is procurement of resistors.
i don't know where i can get those Vishay/Dale NH-50 resistors.
are there good alternatives instate? Caddock MP930 maby?
international shops are also welcome.

* nelson pass suggest in the docu: "C1 through C4 should be high as possible" ok, i could realise this, but i also think about, to use higher quality caps, unfortunately expensiver ones.
with limited money, it would be a compromise: mass or class. what do you think? what (C1) value is necessary with a 24V/ 700-1000VA transformer per channel?


thanks with best regards,
Daniel

[akira]

Hi Daniel

I m using the MP930 from Caddock, it s fine, although it s a matter of taste ... mouser.com sell it in the US for a good price.

Regarding the Watercooling, I wanted to do it also. But there are some problems. I ve got a watercooled computer but the heat amount is VERY different. A cpu is about 100 W and a 10W SOW is about 6 times more. You have to find a very efficient radiator to cool the water.

Almost all the radiators used in computer WC are meant to be used with fans. Very few work passive. To be honnest, the only thing that work without fans is a tube of 25m copper. And this is for 100W ... To use fans with a first class amp is a pitty, it will degrade the sound quite a lot.

The second question is the temperature you want to achieve. The third topic is the temperature of the water. Most of the pumps don t like hot water. For example maxijet limit temperature is about 35 degrees wich is very low for a WC.

There was a topic (very long) about WC an ampifier (try seach) on diyaudio.

Still I very interested if you build a WC for you SOZ, keep posting und viel Gluck von Strassburg.

Ciao

Akira

[Henrik]

Hi Daniel from Vienna!

i hope it's a practicable thing, to drive the SOZ unbalanced without active pre-amp (just a poti behind CDP)
if it is, i want to build a ~10W version.

If you drive the SOZ from an unbalanced line you will loose some gain, and thereby make it even less efficient than it is already, and you will also get more distortion. I have tried it, and I can´t recommend it.
If you want to drive it unbalanced you shoud use an input transformer or some other kind of conversion.
If you have speakers at 93 db, you will get some very loud music from a 7W SOZ with about 20V rails.
Many people don´t like fan cooling, bu I do, and if you pick up the right fans and uses them in a suitable way, everything turns out nice. Actual a lot of SOZ´s has bin bulided that way, just check the Passdiy gallery.
I know SOZ is simple, but on the other hand, don´t underestimate the heatdissipation, I did that twice before I got it right.

Happy building, and let´s her from you again.

[Danman]

hi,

thanks for your suggestions!


regarding watercooling: there are, also in Austria, some companies providing a lot of professional stuff therefor.
for example: http://www.dau-at.com/ger/index.php

unbalanced: ok, i think i will buy a DAC with balanced output-stage next time.

what amp would you suggest me to build?
quality of sound is first priority
~10W are enough.

at first i thought of the original ZEN. than i read in a comparison, that the SOZ would be much better. in this forum i read, the X-SOZ is better than SOZ.
(the X-SOZ-tread is pretty large. -is there a final, working wiring plan?)
all a question of taste, i know, but what to you think?

thanks and regards,
Daniel

[Mad_K]

Originally posted by Danman

with limited money, it would be a compromise: mass or class. what do you think? what (C1) value is necessary with a 24V/ 700-1000VA transformer per channel?

I definately vote for quality caps (quantity). I experienced with this in my SOZ. For a 25W SOZ I would use something like 4 33000uF RIFA PEH169 per channel, see http://www.evox-rifa.com/europe/elec...ic_cap_cat.htm (with chokes)

OR, if on a budget 2 pcs RIFA PEH200 47000uF per channel (without chokes).

[Henrik]

You could take a look at my XSOZ, but be aware of the low inputimpedance (120 Ohm singleended), it isn´t likely you can drive it from a cdplayer, I think you need a preamp with high cururrent driving capabality as my XBOSOZ.

http://www.diyaudio.com/forums/show...9&pagenumber=17

JH6YOU have also made an XSOZ, wich is different from mine, I cant remember the page of his design scematics.

[Henrik]

Sorry, the link is:
x soz

[Danman]

hi,

>>but be aware of the low inputimpedance <<
yes, that's a important point for me, because i really want to drive it only with a CDP.

ok, so i will build an original SOZ at first.

one more issue: i want to realise a highpass to free a 5"-fullrange-driver from the lower frequencies (starting at ~150Hz).
what do you think, which version would give a better result:

* to put a passive crossover between CDP-outputstage. like this: http://www.t-linespeakers.org/tech/f...ssiveHLxo.html
i worry about, that i would have to build that for (-)- and (+)-input, because it's balanced. -maby problems with offset?

or * to use output-Caps, like here: http://www.geocities.com/fuherb/images/SOZ.gif ..and choose a value fitting to the wanted lower frequency.

thanks
Daniel

[ralf]

...conected to a cd player.
it has too less gain. i tried it with 91 db speakers. without preamp - no chance.

if you wnat to connect directly use Aleph.

greets,

Ralf

[Danman]

hi ralf,

also driving it balanced, no chance?

greets,
Daniel