Dropper resistors are used to drop some voltage if it is too high. They are usually connected in series. I wanted to reduce the voltage my regulators so Stephan suggested i use a dropper resistor.
UK Vintage Radio Repair and Restoration - Dropper Calculations
NP0 (zero, not letter o) refers to the type of material used as the insulator or dielectric in some capacitors. I had not realised but it seems to be considered good for audio.
EIA Class 1 dielectric - Wikipedia, the free encyclopedia
UK Vintage Radio Repair and Restoration - Dropper Calculations
NP0 (zero, not letter o) refers to the type of material used as the insulator or dielectric in some capacitors. I had not realised but it seems to be considered good for audio.
EIA Class 1 dielectric - Wikipedia, the free encyclopedia
My first post in this forum.
Hello to all.
Ordert the kit weeks ago.
Build with changes testet by MilesCampbell.
Great thanks to him.
All el-capacitors Panasonic FC other wima MKT.
Input 1UF wima MKT bypassed with 0,022UF on the solderside.
The pot will be changed to an alps.
Now i'am looking for a nice case.
Sounds great from the beginning.
Tested first with cheap earphone.
Later with DT911 250 Ohm.
This is my first diskret headamp after
some cmoy.
Now some pic.
More will follow if the amp is boxed.
Thank you all for your very helpful comments.
Hello to all.
Ordert the kit weeks ago.
Build with changes testet by MilesCampbell.
Great thanks to him.
All el-capacitors Panasonic FC other wima MKT.
Input 1UF wima MKT bypassed with 0,022UF on the solderside.
The pot will be changed to an alps.
Now i'am looking for a nice case.
Sounds great from the beginning.
Tested first with cheap earphone.
Later with DT911 250 Ohm.
This is my first diskret headamp after
some cmoy.
Now some pic.
More will follow if the amp is boxed.
Thank you all for your very helpful comments.
MilesCampbell explains on post 152 http://www.diyaudio.com/forums/headphone-systems/159202-jlh-headphone-amp-16.html#post2643476
I prefer not using variable resistors. I hate them
.
It just works.
The caps are not necessary like in the original build.
DC offset not measured now. But will do it.
I prefer not using variable resistors. I hate them
.It just works.
The caps are not necessary like in the original build.
DC offset not measured now. But will do it.
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So I:
Bypassed the rectifier diodes with 47nF
replaced power supply caps after regs with Nichicon FG
Replaced the zeners with 3 1n4148
changed 220pF to 47pF
Bypassed the input cap with another .47uF to make 1uF
Changed 470R to 2k2
Changed the 100uF caps to cerafines
Removed the 100nF caps Miles recommended
removed the 330pF cap
added 10R dropper resistors
changed 4k7 to carbon film
Some made a bigger difference than others. Now the sound is smoother, crisper, tone is better. (all subjective of course)
I also found i could change the flavour of the sound by using different caps on the output. Silmic had more bass and layed back, Nichicon ES more detail and lively. Could even swap between depending on the recording, music, mood.
Not sure how it compares with other headphone amps as i've never had a decent one before.
Keep meaning to bypass the pot to see what influence it has on the sound but not tried it yet.
Bypassed the rectifier diodes with 47nF
replaced power supply caps after regs with Nichicon FG
Replaced the zeners with 3 1n4148
changed 220pF to 47pF
Bypassed the input cap with another .47uF to make 1uF
Changed 470R to 2k2
Changed the 100uF caps to cerafines
Removed the 100nF caps Miles recommended
removed the 330pF cap
added 10R dropper resistors
changed 4k7 to carbon film
Some made a bigger difference than others. Now the sound is smoother, crisper, tone is better. (all subjective of course)
I also found i could change the flavour of the sound by using different caps on the output. Silmic had more bass and layed back, Nichicon ES more detail and lively. Could even swap between depending on the recording, music, mood.
Not sure how it compares with other headphone amps as i've never had a decent one before.
Keep meaning to bypass the pot to see what influence it has on the sound but not tried it yet.
Hello,
I got JHL kit for ebay on my table right now. I mainly buy this for quite good pcb. Some of you written about offset issues, which rise when apm is powered up and getting low after warm-up. I was thinking instead adding dc serwo maybe it would be better add something like this:eBay - The UK's Online Marketplace What do you think?
Regards,
Michał
I got JHL kit for ebay on my table right now. I mainly buy this for quite good pcb. Some of you written about offset issues, which rise when apm is powered up and getting low after warm-up. I was thinking instead adding dc serwo maybe it would be better add something like this:eBay - The UK's Online Marketplace What do you think?
Regards,
Michał
Is Miles still around?
I was waiting his findings and ideas on how to put the optocouplers for volume and how to implement an effective dc servo (out of the signal path)...
And about output transistors. The regular JLH power amp sounded BETTER with the original ones and replacements were difficult. Here we have much bigger choice and I would look into toshibas (cant help since i like the sound of them) -small power parts are reasonably cheap.
BTW it seems to me that making a pcb run of the original JLH headamp first circuit would be a good idea, maybe integrating psu and dc servo.
Lastly, how these PCB
http://www.diyaudio.com/forums/sili...ree-jlh-hifi-headphone-amp-pcb-0-008-thd.html
look like to use as starting point rather than the ones on ebay?
For starters, the channels are SEPARATED and so is the psu.
Comments?
I was waiting his findings and ideas on how to put the optocouplers for volume and how to implement an effective dc servo (out of the signal path)...
And about output transistors. The regular JLH power amp sounded BETTER with the original ones and replacements were difficult. Here we have much bigger choice and I would look into toshibas (cant help since i like the sound of them) -small power parts are reasonably cheap.
BTW it seems to me that making a pcb run of the original JLH headamp first circuit would be a good idea, maybe integrating psu and dc servo.
Lastly, how these PCB
http://www.diyaudio.com/forums/sili...ree-jlh-hifi-headphone-amp-pcb-0-008-thd.html
look like to use as starting point rather than the ones on ebay?
For starters, the channels are SEPARATED and so is the psu.
Comments?
So this thread is still alive ! But no Jap transistors in sight ?
I've been wanting to do this for a long time but couldn't. So now I'll build the JLH using Jap transistors and see what comes out of it. Maybe I'll build the split supply version with relay protection in case of a large dc offset. No dc servos or output coupling caps. I think tripping can occur under about 30 to 40 mV dc which is still over 10dB below the 1mW rating. So the dc will not burn out the coil.
Might take some time as I'm not completely 'free'. However I've collected all the parts. Need to work out the supply and protection and build a prototype pcb. Lots of other changes here with a better source etc. Hope it turns out well !
I've been wanting to do this for a long time but couldn't. So now I'll build the JLH using Jap transistors and see what comes out of it. Maybe I'll build the split supply version with relay protection in case of a large dc offset. No dc servos or output coupling caps. I think tripping can occur under about 30 to 40 mV dc which is still over 10dB below the 1mW rating. So the dc will not burn out the coil.
Might take some time as I'm not completely 'free'. However I've collected all the parts. Need to work out the supply and protection and build a prototype pcb. Lots of other changes here with a better source etc. Hope it turns out well !
OK.
I don't have a pcb yet ! I will be making one for this project. Remember that I wanted to include a protection relay which isn't there on any of the current boards. Besides that I want to mount the power transistors so that they all sit on a sheet of aluminum that I want to use as the base. Currently most boards require individual heat sinks.
I don't want to talk too much about it. If I do, then I might never get it done !
I don't have a pcb yet ! I will be making one for this project. Remember that I wanted to include a protection relay which isn't there on any of the current boards. Besides that I want to mount the power transistors so that they all sit on a sheet of aluminum that I want to use as the base. Currently most boards require individual heat sinks.
I don't want to talk too much about it. If I do, then I might never get it done !
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Hello
My first post to this list and please excuse my lack of proper English.
I have build the JLH Headphone Amp on PCB's from Enjoy in your hi-fi project, diy tube amp, amplifier diy, amp diy
And I must say that the results is disapointing, it is a weak amplifier with no power to match my old Koss HV/1a Headphones.
I have done some of the modifications recomended in this tread, but it made no change that is worth talking off.
I have been building several Headphoneamplifieres, but only one design has found place in my heart and I have build many of them in defferent versions since 1980.
You can have idea of the design here, it is also Class A
http://www.sandcastle.dk/artikler/HP%20Amp.pdf
I am building on a tube amp, I hope that it will do me good
Regards from Denmark
Max
My first post to this list and please excuse my lack of proper English.
I have build the JLH Headphone Amp on PCB's from Enjoy in your hi-fi project, diy tube amp, amplifier diy, amp diy
And I must say that the results is disapointing, it is a weak amplifier with no power to match my old Koss HV/1a Headphones.
I have done some of the modifications recomended in this tread, but it made no change that is worth talking off.
I have been building several Headphoneamplifieres, but only one design has found place in my heart and I have build many of them in defferent versions since 1980.
You can have idea of the design here, it is also Class A
http://www.sandcastle.dk/artikler/HP%20Amp.pdf
I am building on a tube amp, I hope that it will do me good
Regards from Denmark
Max
Hi Max,
something is amiss here, if anything this amplifier has power.
I can easily drive both pair of my headphones (32&600 Ohms) to levels that can cause hearing damage.
I am not familiar with your headphones but I presume they are an easier load than small 2-way bookshelf speakers that I also tried on this amp, I beleive someone else in this topic successfully tried that too.
Hope you will get it sorted
Marko
JHL to JLH the hard way
Hi everyone,
Looks like this thread has now pretty much dried up now but i will add to it just to thank milescampbell, hotiron, badgerboy and others for their previous very informative postings. I also bought the Chinese JHL Headphone Amp fully assembled kit around xmas 2012 and have just got round to setting it up. However, i did this before i read this thread and although the amp sounded OK, it was dull and flat sounding. Armed with all the info on this thread, i stripped out all the bad/duff components and turned it into the JLH version that sounds far far better. I dont have any specialist audio test equipment but it sounds pretty good to me, i can listen to it as a headphone amp for my Sansa Clip+ MP3 player and also use it as a pretty decent Class A Pre-amp. I incorporated most of the changes but used replacement components that i had available, as near to the recommended values as possible. I did not change the feedback gain setting because i want to also use the headphone amp as a pre-amp and the existing 20dB gain was fine for that. Besides, the original reason for buying the kit was although the Sansa is a pretty decent multi-format music player, it struggled to drive my 32 Ohm Koss PortaPro headphones to a decent listening level.
I cant really add anything instructive to the original thread but at least i can share my pics of the headphone amp and the seperate PSU. I built the seperate PSU because i like to re-use parts for other audio equipment i might build in future and it seemed strange to take a very high quality, low noise headphone amplifier and stick it in a box with a humming mains transformer. OK, the real reason was the case i bought was too small Everything bought cheap from Ebay and Maplin (the case was only £13 inc post) Enjoy!
Hi everyone,
Looks like this thread has now pretty much dried up now but i will add to it just to thank milescampbell, hotiron, badgerboy and others for their previous very informative postings. I also bought the Chinese JHL Headphone Amp fully assembled kit around xmas 2012 and have just got round to setting it up. However, i did this before i read this thread and although the amp sounded OK, it was dull and flat sounding. Armed with all the info on this thread, i stripped out all the bad/duff components and turned it into the JLH version that sounds far far better. I dont have any specialist audio test equipment but it sounds pretty good to me, i can listen to it as a headphone amp for my Sansa Clip+ MP3 player and also use it as a pretty decent Class A Pre-amp. I incorporated most of the changes but used replacement components that i had available, as near to the recommended values as possible. I did not change the feedback gain setting because i want to also use the headphone amp as a pre-amp and the existing 20dB gain was fine for that. Besides, the original reason for buying the kit was although the Sansa is a pretty decent multi-format music player, it struggled to drive my 32 Ohm Koss PortaPro headphones to a decent listening level.
I cant really add anything instructive to the original thread but at least i can share my pics of the headphone amp and the seperate PSU. I built the seperate PSU because i like to re-use parts for other audio equipment i might build in future and it seemed strange to take a very high quality, low noise headphone amplifier and stick it in a box with a humming mains transformer. OK, the real reason was the case i bought was too small
Everything bought cheap from Ebay and Maplin (the case was only £13 inc post) Enjoy!
