x soz

Henrik

hi Henrik.
thanks for posting the pics of your new X Bosoz.

absolutely fine work !!!

i am curious about your final description of the diference between your old - and the new one.

please let your xbosoz connected to mains next 2 or three days to break in the new parts.
and the tell us "unbiased"😀 ....

Ralf
 
Henrik

Looking at the inner side layout, I believe that the construction is based on your advanced plan and technique. The layout looks very systematic. The works done with the veroboard (or breadboard or perfboard) are amazing. P2P soldering looks like an art and wire-wrap is impressive. And, ...
:wiz:

Only one thing... I can see RCA connectors only.
Do you have any special reason why no XLR connector?

JH
 
Ralf, jh6you and JDeV
Thanx for the "roses"!

The wires at the boards and the interconnections is made with solid OFC cobber core without isolation, I stripped some old Tara Labs loudspeakercable.
I used some of it for about 6 Years ago, and even today they shines as the are new, except from where I touched them with my bare hands while mounting, here the looks terrible because of heavy oxidation. So I desided to use these wires in my new project, but this time without touching them with my hands, only with tongs.
I am using the silver solder from Monitor Cabel, it is the easiest and best solder I ever tried, and if You hit the right tempreture, the fluss-medium works perfect and without burning.

jh6you
I don´t use XLR because I dont like them, mostly for aesthetically reasons. It is easy to just put one more RCA besides the singleended RCA to obtain balanced operation. For commercial products XLR´s are more manageable to the consumer, but for DIYers this should not be a problem.

JDeV
I am shure this thing will bring me many pleasent houres, it already has.
I don´t use 6 fets, only two. What You se is 4 Holco resistors, it is those with only two pins.
I can tell, my fets is running hot, not only the fets at the PSU but also the other fets and also the power resistors, that is why I have mounted them on the bottomplate, wich is made of 3 mm aluminium. The bottom plate runs at 23 degere C above ambiet when box is closed, wich is absoloutely the max. temp. for my taste.
In my first BOSOZ I had to install some small fans to cool the preamp fets and som big heatsinks for the fets in the powersupplies. The problem is, that the total heatdissipation is about 25Watt, and if You uses a little box as mine without any airflow to the outside world only inside airflow by fans, then the air inside becomes a little ove 45 degree C with a roomtemp. at 20 degree C. In this case the smaller heatsinks like Yours becomes 50-55 degrees C or so.
Your fets at the powersupply dissipates 3W each, because You run both channels from the same supply. I f I were You, I would do something about that. 50 degree C at heatsings is max.
By the way, I have measured heatsinktemp. by using a modified roasting thermometer, I just drilled a 4mm hole, in wich I put the sensor and som heatsink greese in between. This works nice.

Happy New Year to all.🙂
 
The solid OFC cobber wire I used is 1mm in diameter.
Here is a pic of my thermometer.
 

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For your info, mine is with 6 FETs (+/- 30V).
All six are attached directly to the 1.5mm aluminium bottom plate of the chassis.
The temperature of the bottom plate is measured about 20 degC above ambient.

JH
 

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jh6you

Actually, when I saw that You had mounted Your fets to the bottomplate, I realised that this was the best way for me too, and it just turned out well, a little at the edge, but it´s ok.

Not many have talked about the heatdissipation from the BSOZ, it is somthing You need to deal with.

Yours is running at 2*30v and only 40mA pr. channel, even then You get as high as 20 degree C above ambient. What is Your Voltage before regulation?

I am running 70 mA per channel, this means 2*82v (before regulation) at 70mA per channel, wich is 25W total. This 25W gives me 23 degree C above ambient at the bottomplate. My box is made of metal, and therefore it don´t isolate as much as Yours made of plywood, I think that is the explanation of the close tempreture we are measuring, even Yours is running at < 12W total.
Do You have any airflow through Your box?