Kit headphone amp recommendations

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colin.hepburn
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Post by colin.hepburn » Wed Feb 29, 2012 2:32 pm

Yep I must get on with my jlh Headphone amp build as well to busy with valve amps :P at the mo thou bear in mind if you get one and if you choose standard shipping you will wait a lest 30 day for it that’s the only downside of this kit
Colin
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richardcooper2k
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Post by richardcooper2k » Sun Mar 11, 2012 10:38 pm

After coming across the JLH kits on Ebay i didn't resist and bought one for myself.
I'm not really a headphone listener as i like to feel the music with my body.
But after seeing the kits on ebay for £14 plus post and packing..... (conveniently ignoing the transformer is going to cost more than the kit)

And i didn't have a way of connecting headphones to my system.

In the end i paid a little extra from a UK stockist (japanbox) but the P & P was less so overall not such a big difference in price.
And it arrived in 2 days !

It is built and sounds OK but very different to my power amp and speaker's presentation. And with no previous experience of head amps i'm not sure how to rate it.
DC offset on the output varies as it warms up but most people on Diy audio seem to add output coupling caps or a servo circuit.
Have only used the supplied parts as yet and not tried any of the mods like reducing the gain.
7812 and 7912 heat sinks get quite hot (i'm getting 18V off the 15V transformer which probably isn't helping). Might reduce the standing current.

Anyone else built one and made any changes ?
PS don't tell anyone there aren't any valves in it :)
Thoughts are just little stories that our brains tell us !

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colin.hepburn
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Post by colin.hepburn » Tue Mar 27, 2012 2:48 am

Yep my JLH Heaphone amp is still in its box im to involved with valves at the moment i liked your comment about you like to feel the music with my body
Well sir with the right H amp and headphones you can believe me 8)

Edit Oops :) that should read with your body not my body :oops:
Last edited by colin.hepburn on Tue Mar 27, 2012 12:54 pm, edited 2 times in total.
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andrew Ivimey
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Post by andrew Ivimey » Tue Mar 27, 2012 8:25 am

Okay, in the next few days I promise I will get my JLH up&running. Then I can listen to the music with your body, Colin. I didn't know you knew Richard that well.

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Dave the bass
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Post by Dave the bass » Tue Mar 27, 2012 9:01 am

andrew Ivimey wrote:Then I can listen to the music with your body, Colin. I didn't know you knew Richard that well.

arff arff.
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richardcooper2k
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Post by richardcooper2k » Tue Mar 27, 2012 11:47 pm

OK, made some changes, see circuit 1 for reference to part numbers, http://www.tcaas.btinternet.co.uk/jlhphones.htm
So I:

Bypassed the rectifier diodes with 47nF (not shown on circuit)
replaced power supply caps after regs with Nichicon FG (not shown on circuit)
Replaced the zeners used in the kit(shown as D1 and D2 combined on circuit) with 3 off 1n4148
changed C3 220pF to 47pF
Bypassed the .47uF input cap with another .47uF to make 1uF
Changed R5 470R to 2k2
Changed the 100uF caps to cerafines
Removed some of the 100nF bypass caps
removed the 330pF cap C5
added 10R dropper resistors as i was getting 18V off the transformer and the regs (not shown on circuit) were getting hot
changed R2 and R7, 4k7 to carbon film

Some made a bigger difference than others. Didn't notice a difference with all changes but may have been some cumulative effects. 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 1000uF coupling 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. Makes my power amps/speakers sound a bit ssllooww but still can't match them for tone or being un fatiguing (although it is by no means bad with the mods.
Keep meaning to bypass the pot to see what influence it has on the sound but not tried it yet.
Just need a biscuit tin or something classy to put it in now....

I wonder what it would sound like through Colin's body ?
Thoughts are just little stories that our brains tell us !

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