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Old 21st February 2014, 03:59 PM   #1
Dan P is offline Dan P  Sweden
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Default Testing the Zen-Lite

Hello!

My Zen-lite is almost finished. And it is time to test it. I build the balanced version (fig 16) in the article ”Zen- lightenment” by Nelson Pass. I got 17, 2 volt at the output and the difference between left and right is about 20 mV so it´s seems ok.
I used the IRFP 240PBF since I could not find the IRFP240
I´m about to build the bride of Zen but I want to try if the Zen-lite is working.
My plan was to use my IPod headphone output and connect it to the Zen-Lite input. The connection is ground IPod to ground Zen lite and positive IPod out to Zen lite input.
I tried this but the sound from the speaker is very week even at full volume. It almost sounds like the IPod drives the speaker. It is the same at the other channel. My question is if I can test the Zen Lite this way or is the IPod headphone (unbalanced) output a mismatch for the Zen lite ?
Or do you think there is something wrong with the Zen lite ?

Best regards
Dan Petersson
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File Type: jpg Zen lite 3 komp.jpg (67.1 KB, 326 views)
File Type: jpg Zen lite 2 komp.jpg (70.6 KB, 318 views)
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Old 21st February 2014, 05:31 PM   #2
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Hi Dan,

Always good to see a Zen-Lite!

For the balanced Zen, did you ground one of the inputs or are you driving
both inputs using the i-pod output? (I think it should be the former.)

Cheers,
Dennis
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Old 21st February 2014, 06:03 PM   #3
Dan P is offline Dan P  Sweden
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Hi Dennis
My first try was only one channel to the IPod and then the other.
I just tried to connect both inputs of the Zen-lite (+) and (-) to the IPod (+) and (-) but the result was the same on both channels.
In the Zen-lite I grounded: out(-) and in(-) and the rest of the ground in the schematic to a single point.
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Old 21st February 2014, 06:50 PM   #4
juma is offline juma  Serbia
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Dan P,
it doesn't work that way. Balanced ZEN amp has two inputs (+ & -) on every channel and the common ground. Your IPod has only one output and the ground, so to test the ZEN-E you'll need to create a balanced signal from the IPod (with Balanced Zen Line Stage for example).
For now, you can only test half of one channel at a time (every channel of your amp has two amps). Do it this way:
ground one input of the channel (say -). Put signal of IPod's one channel on the other input (+) of the same channel and connect the speaker between the ground and that half-channel's output. Don't forget to put the coupling cap (say 4700uF) in series with the speaker.
Repeat the same for the other half-channel amp etc...
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Old 21st February 2014, 06:53 PM   #5
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and the Zen light requires a lot of input drive to get to full power! your ipod will not have enough output voltage.
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Old 21st February 2014, 10:37 PM   #6
Dan P is offline Dan P  Sweden
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I try to understand. I see only two inputs and two outputs in the schematics at (fig 16) and two IRFP 240. I assumed that it was a dual channel construction (left and right) with one IRFP240/channel and the (-) output / Input was the ground.
Total of two 300 watt light bulbs / channel. . But is the figure 16 just showing a mono construction witch means to get a stereo I have to build one more ?
When I look at the picture on the last page I noticed two outputs so I thought it was the stereo construction in fig 16.

Dan P
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Old 21st February 2014, 11:11 PM   #7
juma is offline juma  Serbia
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No. The pic 16 shows one balanced channel. Read the article carefully, google for balanced audio - it's too long a story to explain it completely in few sentences. Try to understand what's really going on, or you are in trouble.
Of course, you can use the circuit from pic 16 as stereo amp - every input for one channel, but you'll need two speakers (each connected between one of the output points and the ground). If you want to make it work that way, the coupling caps (4700uF or more, serially connected, one with each speaker) is mandatory.
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Old 22nd February 2014, 08:39 PM   #8
Dan P is offline Dan P  Sweden
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I made a simple sketch of my original plan to set up the system. I´m building a Bride of Zen as soon as the parts gets here. Hopefully the combination will work fine. I hope the problem with the test was as suggested the low output voltage.

I the text Pass mention “Another potential benefit to balanced operation is the elimination of the output capacitors as illustrated I fig 16” so I did not plan from the beginning to connect a capacitor serial with the speaker.

Is the picuture correct for the the coupling caps ?

Is my schematics correct for BOZ to Zen-Lite or have I missed something ?
Best regards
Dan Petersson
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File Type: jpg zen _0001.jpg (803.9 KB, 209 views)
File Type: jpg zen 2 speaker.jpg (66.4 KB, 185 views)
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Old 22nd February 2014, 08:52 PM   #9
Zen Mod is offline Zen Mod  Serbia
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thinking is OK , caps are OK , just re-check pinout of XLR

1 gnd
2 positive
3 negative

include 100-220R/1W resistors ditto at speaker terminals (between hot and gnd) , to bleed those caps , in case of disconnected speakers
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Old 22nd February 2014, 10:15 PM   #10
Dan P is offline Dan P  Sweden
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Hello again: The output cap value was a bit to high in the fig. I Think I go for a cap rated: 6800 uF/100 Volt DC.

Dan P
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