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
.... 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
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.
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.
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
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
Check HeadWize - Project: The Zen Headphone Amplifier by Marcello Pellerano for more detail. O headfi.org diy sectuion for advice.
Vlad
Vlad
TODAY
Here is my ZEN like headphone amplifier. I have finished it today after reading this tread. Since a few of you here have had some humm troubles,i have used two 4700uF per chanel at PSU board and one 3300uF at each amp-board. I have redrawn PCB so it fits with my heatsink,the PSU board and Timer-Eq. boards are as the author suggested. I have wired it just as it is in "Power connections" pdf and there is no audio humm at all. I´d say it has a lack of hi-frequencies but it still sound wery wery pleasant. Thanks for this project mr. Marcello Pellerano!
Here is my ZEN like headphone amplifier. I have finished it today after reading this tread. Since a few of you here have had some humm troubles,i have used two 4700uF per chanel at PSU board and one 3300uF at each amp-board. I have redrawn PCB so it fits with my heatsink,the PSU board and Timer-Eq. boards are as the author suggested. I have wired it just as it is in "Power connections" pdf and there is no audio humm at all. I´d say it has a lack of hi-frequencies but it still sound wery wery pleasant. Thanks for this project mr. Marcello Pellerano!
Attachments
It may be that my ears got used to listen to this amp or it may be something else,but i´d say that now there is no previous lack of hi-frequencies. It sounds really good!
Here is my version of PCB (100x67mm) ,if someone needs it:
Here is my version of PCB (100x67mm) ,if someone needs it:
Attachments
Hi all I made the amplifier but I discovered that the sound I get is rly rly low...or how to put it quiet! I have to put to max everything to can hear normally the sound! Is there possibility that I did something wrong? I measured the Transfo that gives me 25V instead of the 18 that I ordered it . ______ . could that be the case? Sorry for the question but I am not really into electronic just like to make things and soldering (and few things that I have read)... and that is as far my knowledge goes. The Headphones I use are Superlux HD 668B which are 2x56 Ohms. Ideas?