10w Xsoz

[Henrik]

Hi Variac
Caps it is.
My brain must have ben X'ed last night 😀

 

[Variac]

Henrik,

I am using Super-e coupled BGNx's

Ok, Iwas looking at the older and newer schematics, and discovered that the older had a total of two 220 uf caps in the entire amp.

The newer one has (4) 220 uf caps. You have put a pair in parallel in place of one on each side. That is the Super e coupled concept?

Can I still use only one 220 uf cap on each side of the circuit? (2 caps total in the amp?) Or is it better to use a single 440uf?
Whats the total uf of the paired caps? -would be 440, no?
Is the capacitance not that critical?

Wow- first I need to know how to wire inductors-now caps. This is becoming Electronics 1, but it's nice to have "instructions" in one place here 🙄

 

[Henrik]

Hi Variac

The newer one has (4) 220 uf caps. You have put a pair in parallel in place of one on each side. That is the Super e coupled concept?

Yes.

Can I still use only one 220 uf cap on each side of the circuit? (2 caps total in the amp?) Or is it better to use a single 440uf?

Yes. No.

Whats the total uf of the paired caps? -would be 440, no?

Yes.

Is the capacitance not that critical?

No, everything >220uF.

Regards Henrik

 

[Mad_K]

I couldn't resist..

Sorry Henrik, I just had to try to loose the X-feedback.. (You know when the little green tweak-monster comes out )

Well, there is definately a difference, but not as huge as I would have suspected... In fact I'm still enjoying the amp very much, and I'm not shure if I will change it back.
The trigger for all of this is that I'm building a "Pacific Riaa Pre" and need higher input Z on the XBZLS. Also, I want to try how a completely feedback-free amplifier chain works out (among other things).

This week I have started to get the hang of simulating with EWB5, so I promise I will not ask you (Henrik) to do it for me again 😉

 

[Mad_K]

I couldn't resist II

XBZLS->BZLS.

XBZLS+XSOZ=

but also definately

BZLS+SOZ=

/Mad_K listening to "Counting Crows - Across a Wire" and is on

 

[Variac]

I think I'm in Mads K's situation - but different!😀

I am planning to hook my Xbosoz to two amps- an xsoz and a HAfler 220 for bass. I am hoping to have the output from the pre go directly to my Xsoz, but also have the output hooked to an active low pass filter, a volume pot and into my Hafler and to my bass driver.

I guess I would connect them both in parallel after the output pot? Then I would have another pot only in the wires to the HAfler? Then the active crossover? MAybe the level control for the bass goes after the active crossover?

Now the point- will the mods to the XBSOZ vs. the BSOZ make a difference when the preamp is driving into BOTH
1. an XSOZ and my mid/tweets
2. an active filter and a level control, and my Hafler and my bassdriver.

I guess this is about the same situation as any subwoofer, though mine is a woofer not a sub.

 

[Mad_K]

<<I guess I would connect them both in parallel after the output pot?

yes (the XBZLS does not use a pot at the output, only BZLS)


<<Then I would have another pot only in the wires to the HAfler?

can't do that

<< MAybe the level control for the bass goes after the active crossover?

that you can do

<<Now the point- will the mods to the XBSOZ vs. the BSOZ make <<a difference when the preamp is driving into BOTH
<<1. an XSOZ and my mid/tweets
<<2. an active filter and a level control, and my Hafler and my <<bassdriver.


you have to use XBZLS to drive XSOZ because of the 120 ohm input Z...

 

[Henrik]

Hi Mad_k
Don't feel sorry about your inner green tweek-monster, they are so natural around here.

How you react on the difference between X and no X is a personal matter.
That said, I am into the X'ed versions. I had a setup running, where I could switch in and out of the X, I alwas returned to the X'd modes of both SOZ and BSOZ (BZLS). I also think that the rest of your setup plays an important role in the subjektive evaluation of the X.
The most important thing is to release your inner green tweek-monsters, and then let's read about all the joy and sufferings they will bring you.

Hi Variac
I have never tried biamping, so I can't really tell, but why not

 

[Henrik]

Hi Mad_K, I didn't se your last post.

So Variac, Mads just answered your prayers.

 

[Variac]

Ok I guess it's obvious, the XSOZ is still connected directly to the preamp so the impedence match is still important.

I guess I was asking if the XBOZ is going to work OK being also attached to an active crossover in parallel to the XBOZ . I guess it's all OK. Thanks guys.

 

[Tyimo]

Sound of SOZ?

Hi!
Stupid and maybe boring question, but could somebody tell me what is the sonic differences between the ZEN-SOZ-XSOZ?
I know already the sound of the ZEN and Aleph5 and I am very interested of the SOZ amp.
Thanks

 

[Mad_K]

"The Son Of Zen has a wondeful sound, very direct and clear, without the electronic veil imposed by complex feedback circuits." -NP

It sounds VERY NICE. The only real way for you to find out is to make one 😉 I promise you; you will not regret it...

Comparing to Zen/Aleph = different 🙂

 

[Mad_K]

OK, so I put in a little fan...

-And it works extremely well!

While I was reasonable ok with the fact that my HS ran hot as hiell, I was not equally happy with the fact that the rest of the amp's chassi reached 70'C after some hours of operation. Luckily for me, I had just enough space on my back-plate to fit a nice 60mm fan. I was particulary worried about my rectifier and filter-caps (I didn't dare to measure the temp). This little fan actually makes a big difference; I plan to do some measurements sometime this week, while I adjust the fan-speed/noise. The fan actually lowers all of the temps in my amp, including the fet/resistor heatsinks. The fan draws in cold air from the back, and blows it through the amp where it exits mostly in the gap between the heasinks and the top-plate. (It's not very clear from the pictures, but the amp has rather large openings below and above the sinks -a very effective technique).

While I was extremely unsatisfied with elfa.se's selection of fans and their prices, I remembered (I also tweak/OC my computer) that microplex.no has a very large selection (they even have noise-samples on their fans) and very competetive prices. Browsing through their "bargain" section got me thinking a bit further as they dump the prices on "old" cpu fan/hs combo's they have overstocked. This again led me to check globalcool.no where I got this P4-cpu fan/hs for $10 😀 see http://www.vantecusa.com/p_gsw_6015.html -I bought 6 of them while I was at it; might come in handy later. I can see some ultra-compact class-A or some sophisticated high-power class AB with actice fan-regulation on the horizon. So, I got 6 hs/fan combo's for the price of the 3 fans alone ;----)

Here's a picture of the evil one:

 

[Mad_K]

When I first connected the fan to the psu, I simply used a dropping resistor to get a reasonable voltage to drive the fan (having done it succesfully with computers in the past). The difference between a computer psu and a SOZ however is some thousands more uF of capacitance... The result was that when I turned the amp off, the psu discharged through the fan and it cried like a baby!! It made this high-frequency whine which started at about 5-10kHz and went up/out of the audible range. I don't know what actually happened but don't think dc-fans likes to be force-fed dc current very much. I figured that the fan wouldn't last very long in this arrangement, so I glanced at the A75 article and saw how Nelson did it. So I tossed together this little circuit, and it works like a charm. (You can see it in the picture in the above post). Read the beginning of A75 article part 2 for details on the circuit. Here it is anyways:

 

[Nelson Pass]

Now here's a little trick for you:

DC fans have a higher start voltage than sustained rotation
voltage, so you can throttle them down quite a bit more
if you provide more initial voltage. Try putting a cap in parallel
with the resistor to the positive supply, and some Base resistance
on the transistor, and the initial voltage will be higher, allowing
a lower long term DC voltage with a reliable start.

The cap in series with the Base simply prevents an initially
saturated transistor from taking up all the current from the
cap at once. Try a 1K or something. 😎

 

[Mad_K]

Thanks for the tip Nelson 😉 I think I will implement that trick and a trim-pot for the lower resistor. This way I can let the amp burn in those nice midnight hours together with Tori Amos, while I can crank up the cooling when Kyuss tears down the place in the afternoon 😀

You meant "The RESISTOR in series with the base.." -yes?

 

[Mad_K]

-Come to think of it I won't need both tricks at the same time (cap&pot) 😉 The simpler the better...

 

[Mad_K]

Sox

Ofcourse I had to try it...

What can I say? -I'm on : And I think it's time for a

THANK YOU NELSON!

Here's the schematic the SOX as I buildt it (I hope you don't mind):

 

[finwbu]

blower-controll

for better speed controll

 

[Keld]

Now here's a little trick for you:

DC fans have a higher start voltage than sustained rotation
voltage, so you can throttle them down quite a bit more
if you provide more initial voltage. Try putting a cap in parallel
with the resistor to the positive supply, and some Base resistance
on the transistor, and the initial voltage will be higher, allowing
a lower long term DC voltage with a reliable start.

The cap in series with the Base simply prevents an initially
saturated transistor from taking up all the current from the
cap at once. Try a 1K or something. 😎

Once trying to make a simple "Booststart" circuit for my fan I did as discribed above althoug without the base resistor and it turned out as an exellent little FM radio jammer😀 .
You can also change the "positive resistor" to a NTC and have a temp controlled fan.

Keld
A man a plan a Fan