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-   -   Zen V5 with Laptop Power Supply??? (http://www.diyaudio.com/forums/pass-labs/229850-zen-v5-laptop-power-supply.html)

bigbargain 12th February 2013 12:55 AM

Zen V5 with Laptop Power Supply???
 
Ok, first let me confess, I have a similar questioned posted in the power supply section, but I think the question will solicit different answers from the specifically "Pass" crowd here. Forgive me if I 2x wasted your time.

Here goes....

"
I was at a DIYer's house recently and noticed what he explained to me was a Nelson Pass Zen Variation 5 and right there in the amp was 4 laptop power supplies (the bricks you throw in your bag for when the battery dies...). 2 per channel powering each of the push-pull.

Now this amp design is a class A, so I am guessing its always pulling a lot of power.

So it got me curious and I did some research.
1.) on eBay you can buy 90 watt 19 volt power supplies all day, and cheap. They can deliver almost 5 amps each! Seems like enough if I'm intending to use it for a low mids and up on a tri-amp'd set up (horns, so no real need for lots of power).
2.) Nelson Pass himself says the PS in this amp has to be really clean.
"

In the PS forum, I've gotten a few answers and which included adding CL or CR filters. Of course, I can filter like mad and probably make almost anything work.

So the real question boils down to, does this approach economically produce a the same result? Remember I will be pushing some very efficient horns, so any noise will be more likely heard.

My goal is to avoid building the very big PS Mr. Nelson's design includes if I don't have to (360,000uF of caps alone!)

Thoughts?

Zen Mod 12th February 2013 12:59 AM

go for it

use some RC filtering locally , in amps case

billyk 12th February 2013 01:22 AM

Amp Camp amp... 2x laptop power supplies. Sounds wonderful.

john65b 14th March 2013 03:44 PM

I say go for it too...:)

Chris, I found some 24v 4A power suplies cheap ($10 shipped from China?). Just make sure they don't "mains" ground the PS output ground or you will see smoke, and lots of it.

I have been meaning to buy a few myself...

john65b 14th March 2013 03:50 PM

Found the JFET Babo ZenV5 thread...

http://www.diyaudio.com/forums/pass-...ml#post1152539

bigbargain 17th March 2013 02:04 AM

got a link to these PS's?

john65b 17th March 2013 03:51 AM

Yup...

24V 4A Power Supply AC Adaptor for Strip or RGB LED | eBay

I will get to those JFETS and other transistors tomorrow...

Printer2 18th March 2013 05:59 PM

One thing to consider is that performance specs. from China are not all they are cracked up to be. The 4A rating might be achievable at 240V but at 120V may make 2A on a good day. Bought a few PS's and found them disappointing.

kasey197 19th March 2013 12:41 AM

Quote:

Originally Posted by john65b (Post 3410664)
Found the JFET Babo ZenV5 thread...

http://www.diyaudio.com/forums/pass-...ml#post1152539

Imho If you're going to add the input jfets, might as well go the whole hog and make an F5 ;)

xrk971 22nd March 2013 10:50 AM

Quote:

Originally Posted by bigbargain (Post 3366199)
Ok, first let me confess, I have a similar questioned posted in the power supply section, but I think the question will solicit different answers from the specifically "Pass" crowd here. Forgive me if I 2x wasted your time.

Here goes....

"
I was at a DIYer's house recently and noticed what he explained to me was a Nelson Pass Zen Variation 5 and right there in the amp was 4 laptop power supplies (the bricks you throw in your bag for when the battery dies...). 2 per channel powering each of the push-pull.

Now this amp design is a class A, so I am guessing its always pulling a lot of power.

So it got me curious and I did some research.
1.) on eBay you can buy 90 watt 19 volt power supplies all day, and cheap. They can deliver almost 5 amps each! Seems like enough if I'm intending to use it for a low mids and up on a tri-amp'd set up (horns, so no real need for lots of power).
2.) Nelson Pass himself says the PS in this amp has to be really clean.
"

In the PS forum, I've gotten a few answers and which included adding CL or CR filters. Of course, I can filter like mad and probably make almost anything work.

So the real question boils down to, does this approach economically produce a the same result? Remember I will be pushing some very efficient horns, so any noise will be more likely heard.

My goal is to avoid building the very big PS Mr. Nelson's design includes if I don't have to (360,000uF of caps alone!)

Thoughts?

I had the same question posted in the switching power supply forum but I had even asked if you could parallel the bricks to get more than the 4.6 amps. The thread answered "maybe". There is no doubt connecting them in series with a center common tap for a dual rail supply will work. As you have seen at your friends's house - it works and indeed you get a low cost +/- 19 volt supply that is super efficient and compact. You should try measuring the noise from these, they are much quieter than you think, certainly, nothing a smaller bypass cap cannot handle. Even if it is noisy, the beauty is the noise is at 400 kHz and the 60 hz is wiped out with isolation transformer and switch mode operation. You can't hear 400 kHz even if it gets through. For the Amp Camp Amp, Nelson Pass recommends using SMPS bricks, and said to the naysayers, "get over it". The big iron power transformers used in class A projects has always been the single most expensive part not in including the chassis. You can get high quality HP or other name brand bricks for $5 to $8 ea on Amazon. I want to try the paralleling bricks to increase current.


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