Zen Enlightenment Attained!

Another Zen is born.

I powered up my Zen last night with Talking Heads "Burning Down the House" in the back ground. (Vince :) )

It's output looks great! I can't see any abnormalities in the sine, triangle or square waves. My little function generator can't drive it to clipping. When I connect it to the amp, the generators peak voltage goes down. I'm going to connect it to my pre-amp tonight.

Where can I find information on how to measure THD, etc...?

I only have a sine wave CD, cheap function generator, and an oscilloscope. So, I can't do everything.

Thanks for all your help guys.

pixie
 
Alright, what does LOL mean?

Does anyone remember Elite? Back in the days of 150 baud modems? Instead of symbols, everyone uses abbreviations. The problem is everyone seems to make up thier own abbreviations and others pick up on them. At least Elite was a standard.

I'll let you know what I think of the amp. I'm going to listen to it tonight.

If it works, I'm going to try to change R1 again. I put the old .33 ohm resistor there. If I don't have enough power, I'm going to try the .22 again.

I just read something new about the Zen. It's designed for a 8ohm speaker. My center is 4ohm. What can I do to improve the performance for 4ohms?

Thanks,
pixie
 

vdi_nenna

Member
Paid Member
2000-10-10 7:27 pm
PA, USA
Zen

LOL means laugh on line. I wasn't laughing at you, I was laughing at me, for burning 5 amps til I got it right. Anyway...

To improve the output vs imedance, you need to parallel 2 channels to get at least 10 watts w/ 4 ohms. 2 channels will be connnected in parallel at the input and the output for 20 watts into 8 ohms. With a single-ended topolgy, the wattage doesn't double if the impedance is halved.

Lowering R1 won't help because it will only deliever more current to the power mosfet. It will theoretically lower distortion. You may need more voltage swing. But I could be wrong about this. Someone correct me if I am.

You need to think about this, because about 54% of audio sound tracks in movies come out of the center channel. 10 watts is loud in a small area though. Test it and see how you feel about it.

Good luck dude!

Vince
 

FYC

Member
2001-01-04 10:29 am
Hong Kong
Congradulation!

I would suggest the only thing to do is to use your function generator+preamp to set the bias point for symmetric clipping.

THD measurement etc doesn't make much sense for a simple amp like this, simply you can do nothing about it excepting changing the bias current and the MOSFET!

Set for symmetric clipping and enjoy music.
 
I'm impressed, very impressed, now I need more!

I played music through my center channel speaker and it did sound very pure. It sounds as good as my McIntosh. It had no noise or hum, and it wasn't too bright, like most cheap amps. Not that I'm saying this amp is built like a one built by Sony or Adcom. Both of which I've tried their best and they are terrible.

The problem is even with the pre-amp cutting my mains by 10db and the center pre-amp cranked, I couldn't get the volume I need out of my center. I know, I know, big surprise!? I never expected this to keep up with a 120Watt class-A connected to Klipsch 98db-1W-1m. I can get 110db out of those before distortion of any kind.

So, this is the plan: I'm going to have my father build a second aluminum box and I'm going to build three more of these. One more in this box and two more in a second box. Then I'm going to bolt the second box upside down on top of this one. Thus giving me 40 watts if I parallel them all. It should look cool too. Maybe I'll make an oak face plate. I'll have to get pictures posted for you guys.

OK. Now guys, is there any problem with paralleling four of these things? I also plan to add a Bride of Zen possibly in the same box. Do I need to alter it to handle four?

My transformer is 30V at 7.5amps pri+sec. Is that enough to split between two Zens or do I absolutely need a 30+30V 5amp transformer for two? I will have a second set of bridge+caps. I don't see why not. Does this thing need more than 3.75amps peek?

I plan to buy a 5.1 decoder in a few months. So, I'll need a fifth amp; I only have four. So, this has become a necessity not just a fun hobby.

Thanks,
pixie