Juma's Head Amp

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#301
Hi Everyone,
For past two days I have been reviewing my files+ have been extremely busy in building home theater set-up, along with my carpenter. Slightly OT but here is a snap shot and model in sketchup.
https://3dwarehouse.sketchup.com/model.html?id=e43291be-35ae-4ad6-8dd1-b97357b34bab
I have done lot of hard work to prepare exact models including drivers! Of course, speakers will be turned towards ear of listener...(I will make separate thread on build and experience. )
I am ready to send off the gerbers to boardhouse. Will do that tomorrow hopefully, after one last check!, with 10 day delivery schedule...
reg
Prasi
 
#303
albertNL said:
Hi Prasi,

I've added myself to the list:

xrk- 1 set (1 PSU+1 Stereo HA)
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA)
kram- 1 set (1 PSU+1 Stereo HA)
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)
nicusim-1 set (1 PSU+1 Stereo HA)
potepuh-1 set (1 PSU+1 Stereo HA)
e_fortier-2 PSU
touchdown -1 Stereo HA
albertNL- 1 set (1 PSU+1 Stereo HA)

Thanks
Albert
Click to expand...

Hi Prasi,

Well, I just heard the Juma HA 😉 If not too late I'll take 1 stereo HA besides my 2 PSU. I won't update the list now.

Thanks,
Eric
 
#304
prasi said:
Hi Everyone,
For past two days I have been reviewing my files+ have been extremely busy in building home theater set-up, along with my carpenter. Slightly OT but here is a snap shot and model in sketchup.
https://3dwarehouse.sketchup.com/model.html?id=e43291be-35ae-4ad6-8dd1-b97357b34bab
I have done lot of hard work to prepare exact models including drivers! Of course, speakers will be turned towards ear of listener...(I will make separate thread on build and experience. )
I am ready to send off the gerbers to boardhouse. Will do that tomorrow hopefully, after one last check!, with 10 day delivery schedule...
reg
Prasi
Click to expand...

This will be a nice and great HT set-up.

Rgds,
Eric
 
#306
prasi said:
Hi Eric,
any update on you build?
reg,
Prasi
Click to expand...

Me again...well the Juma HA sang tonight..😉

Well, my test jig is working and it sound really good. Good enough for a nice enclosure. Quick description;
I used a normal LM317/337 regulator from Jim's Audio on e-bay and the HA is dead silent, I'll have to add a LED since I can't tell if it's on.
My PSU was slithly modified, I installed the regulator under the PCB on a 3mm aluminum sheet and now with both channels biased at 150mA each the 317/337 remains cool.

Each channel is cooled by the use of a 12mm thick aluminum plate.

I used a 2.5uF polypropylene input cap and kept R5 as 22k. My xtrm is an Antek 50VA, +/-25Vac I unwinded to get about +/-17Vac.

I used all genuine parts from Digikey (or Mouser) and have no issue getting the right bias with 0mV DC offset. I matched my transistors, that help reducing dc offset.

I joined a picture of my test jig. The size of the aluminum heatsink is huge for a HA (each channel is 150mm x 75mm x 12mm) because I will add a second HA from a different designer just above the Juma HA. I'll be able to select which HA I want to listen.

Sound wise, XRK described it right a few post above.

Take care guys and thanks to Juma and Prasi !

BR,
Eric
 

Attachments

  • Juma HA Test Jig Dec 2.jpg
    Juma HA Test Jig Dec 2.jpg
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Last edited:
#307
e_fortier said:
Hi Prasi,

Well, I just heard the Juma HA 😉 If not too late I'll take 1 stereo HA besides my 2 PSU. I won't update the list now.

Thanks,
Eric
Click to expand...

Hi Eric,
Its not too late, I have ordered a few extra to accommodate few more people later.

xrk- 1 set (1 PSU+1 Stereo HA)
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA)
kram- 1 set (1 PSU+1 Stereo HA)
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)
nicusim-1 set (1 PSU+1 Stereo HA)
potepuh-1 set (1 PSU+1 Stereo HA)
e_fortier-2 PSU +1 Stereo HA
touchdown -1 Stereo HA
albertNL- 1 set (1 PSU+1 Stereo HA)

reg
Prasi
 
#308
i would like 1 set; added myself to the list:

xrk- 1 set (1 PSU+1 Stereo HA)
gannaji- 1 set (1 PSU+1 Stereo HA)
saheb- 1 set (1 PSU+1 Stereo HA)
kram- 1 set (1 PSU+1 Stereo HA)
btesize-1 set (1 PSU+1 Stereo HA)
rumina-1 set (1 PSU+1 Stereo HA)
nicusim-1 set (1 PSU+1 Stereo HA)
potepuh-1 set (1 PSU+1 Stereo HA)
e_fortier-2 PSU +1 Stereo HA
touchdown -1 Stereo HA
albertNL- 1 set (1 PSU+1 Stereo HA)
Malvin - 1 set (1 PSU+1 Stereo HA)

Thanks
 
#309
e_fortier said:
Me again...well the Juma HA sang tonight..😉

Well, my test jig is working and it sound really good. Good enough for a nice enclosure. Quick description;
I used a normal LM317/337 regulator from Jim's Audio on e-bay and the HA is dead silent, I'll have to add a LED since I can't tell if it's on.
My PSU was slithly modified, I installed the regulator under the PCB on a 3mm aluminum sheet and now with both channels biased at 150mA each the 317/337 remains cool.

Each channel is cooled by the use of a 12mm thick aluminum plate.

I used a 2.5uF polypropylene input cap and kept R5 as 22k. My xtrm is an Antek 50VA, +/-25Vac I unwinded to get about +/-17Vac.

I used all genuine parts from Digikey (or Mouser) and have no issue getting the right bias with 0mV DC offset. I matched my transistors, that help reducing dc offset.

I joined a picture of my test jig. The size of the aluminum heatsink is huge for a HA (each channel is 150mm x 75mm x 12mm) because I will add a second HA from a different designer just above the Juma HA. I'll be able to select which HA I want to listen.

Sound wise, XRK described it right a few post above.

Take care guys and thanks to Juma and Prasi !

BR,
Eric
Click to expand...

Great to hear that you like the sound🙂.
Nice idea to have two different HA's in same enclosure, to play according to mood/ track.
reg
Prasi
 
#310
Sorry for OT but just wanted to let folks on this thread know that my simple MOSFET follower amp works. Just got the LU1014D power JFETs today and installed them. The amp is also dead silent - even without any regulation on the PSU.

http://www.diyaudio.com/forums/head...lower-headphone-amplifier-14.html#post4906102

Here is noise measurement with music stopped (DAC still connected) - even in mV range it is 0.0mV (not shown):

583726d1480825131-mosfet-follower-headphone-amplifier-dao-test-noise-03.jpg


Very simple circuit, I modified with a J310 (gate and source tied together for 10mA current source) instead of the J511, and a 6.8v zener plus red LED to get close to 8.2v, and IRFP240 vs SK:

79127d1171013659-mosfet-follower-headphone-amplifier-euvls_hpamp.jpg


This is all DC coupled and running class A at 330mA bias (about 13w heat from heatsink).
 
Last edited:
#311
xrk971 said:
Sorry for OT but just wanted to let folks on this thread know that my simple MOSFET follower amp works. Just got the LU1014D power JFETs today and installed them. The amp is also dead silent - even without any regulation on the PSU.

http://www.diyaudio.com/forums/head...lower-headphone-amplifier-14.html#post4906102

Here is noise measurement with music stopped (DAC still connected) - even in mV range it is 0.0mV (not shown):

Very simple circuit, I modified with a J310 (gate and source tied together for 10mA current source) instead of the J511, and a 6.8v zener plus red LED to get close to 8.2v, and IRFP240 vs SK:

This is all DC coupled and running class A at 330mA bias (about 13w heat from heatsink).
Click to expand...
nice diy style work. congrats!
 
#319
prasi said:
I was thinking, how about a simple UPC1237 based with a DPDT relay protect with a DC detect threshold of +/- 1.5 to 2 V DC. PCB about 40x40 mm. Any comments?
Atleast, phones should be able to survive 2V dc.
reg
Prasi
Click to expand...
With relay there will be signal loss. I have the upc based soft-start/speaker protect for an diy amp, when I am not using the relay vs using the relay i can tell the difference.

I would not give more than 0.5v to my phones.

Sent from my A0001 using Tapatalk
 
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