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Old 14th July 2008, 05:45 PM   #181
alex mm is offline alex mm  Romania
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Default Zen headphone amplifier .....by Marcello P.

.... I'm happy with my Zen headphone amplifier and HD 555 headphons http://i34.tinypic.com/3143wpy.jpg and http://i36.tinypic.com/11vnsyq.jpg the last picture http://i35.tinypic.com/n18qp1.jpg . All the best alex mm
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Old 1st October 2008, 11:29 AM   #182
kimbo is offline kimbo  Australia
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Default At last, my Zen

Well I got it together some months ago. Sound was OK but there was too much noise and hum. It took a lot of work fooling with earthing and leads, but what finally fixed most of it was to move the power cord and rotate the torriod. I had not realized that the radiated hum was so directional. I’d always imagined it to be pretty uniform from a torriod.

The boards were in such poor condition I had to remove all the components and fix them up first. As the caps were already fitted and had the leads bent over, they got pretty hot when I was removing them, so I replaced them with off the shelf caps from the local store and placed an order for a set of Elna Silmic’s which took months to arrive on back order from Digikey. I finally fitted these on the weekend.

* Input caps Solen, the rest Elna Silmic
* The power supply is a pair of Tangent’s TREAD boards using stock LM317AT
* A relay is fitted that bypasses the input straight to a pair of plugs on the rear panel when there is no power. This means that I can have the amp plugged directly into my Yamaha player and the lead from the back of the Zen into the input of my NAD. No fooling around with leads….I just turn on the Zen and the NAD is disconnected. This works well.
* I used a SC speaker protector board to get rid of turn on/off thud ….a relay shorts out the Zen outputs
* I have left room on the font panel for some sort of crossfeed at a later date. I have got Tangents modified Linkwitz crosssfeed and may use that.

My boo boos
1. Because I have never built a class A amp (and it gets pretty hot here in the summer) I way over estimated the amount of heat sinking I’d need. I mounted the LM317s on a very large sink on the LHS under the line of vents in the case. I also went to some trouble to mount the other large heatsink on the rear panel. This resulted in the power supply and fuse being too close to the left channel board and a generally poor layout overall
2. Trying to squeeze it into a 1U high case also meant that some of the caps are too close to the top of the case.

I may rebuild at some stage and move the rear heatsink inside the case and mount it under the second set of vents on the RHS. This would give me a better layout.
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Old 1st October 2008, 11:34 AM   #183
kimbo is offline kimbo  Australia
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some shots....
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Old 1st October 2008, 11:35 AM   #184
kimbo is offline kimbo  Australia
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case....
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Old 1st October 2008, 11:36 AM   #185
kimbo is offline kimbo  Australia
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....and over did it on the PS heatsink....
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Old 9th October 2009, 04:28 AM   #186
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Default Zen headphone amp.

Hi tortello,
I'm going to build a Zen heâdmp but my knowleghe is ... not good . So I need a help to mod zen headphone amp( Zout, gain,...) . I use 100 ohm headphone( yamha yh-2, orthodynamic) anh do you have a pcb orcad file?. I also to mod the pcb.

Thanks you.
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Old 9th October 2009, 04:51 PM   #187
Stream is offline Stream  Russian Federation
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I also want to try this amp with minimal difference from 'reference" schematic.
It will drive my Cresyns CS-HP700 (32Ohm) or Beyer DT880 (250) if it's owner will like this.

So here is my plans:
I'm planning to make handmade PCB (laserprint, have some exp). One symmetrical board for two channels. One trafo with two secondaries.

Power supply: all is as in article, but:
25VA 2*18V Talema (boxed, blue).
CRC filter: 6800uF caps from ca340a, R, 1800uF Pana FC.
Can I use R=4,7 or 10 ohms instead of 5.6 ?

I also have line choke filter, and X,Y caps for STEPS Power supply. And don't know, if it will be usefull here .
BTW choke is Murata PLA10AS3030R4R2B (30MH, 0.4A) If it has enough "current ability"?

Case : Hammond 1455-N2202 (220x103x53mm)

Main:
C2 = Wima MKP 2.2uf - If it's good choise for this position? I can get this for good price...

Thanks for Your attention
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Old 10th October 2009, 03:34 AM   #188
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Anybody have pcb file(orcad, protel,...)???
I will use adaptor 24v-1a, and bybass C2, using c1815(Q3). It's ok?
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Old 11th October 2009, 12:47 PM   #189
Stream is offline Stream  Russian Federation
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Mr. Unknown. What enclosure you want to use? I think I'll make own design for Talema and Hammond, and I'll share it with You. But I use Eagle to design PCBs...
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Old 8th January 2010, 09:00 PM   #190
kenev is offline kenev  Greece
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I was wondering whether I could eliminate NFB completely and what will happen if I do that. Thinking of building this little headamp to drive my HD600s. In fact, I prefer not to use NFB, when this is possible.
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