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Post by Deleted on Jan 20, 2008 0:47:05 GMT
Leo If I read you correctly, you wanted to feed the 7815/7915 into JLH then back into PCB supply points ? If so, and you have a good stock of 7815/7915 it would be worthwhile seeing if you can find a couple with a little over 15V output to make up for some of the JLH loss of around 200mV (?) Alex
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pagan
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Post by pagan on Jan 20, 2008 0:53:42 GMT
Who is going to be first to try to make a small JLH with a 7805 integrated , instead of a current limiter. Should only need a diode across IN and OUT of 7805 for added protection ? Alex Already done, or close enough? www.headphoneamp.co.kr/bbs/zboard.phpkumisa III in a mint tin!!!
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leo
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Post by leo on Jan 20, 2008 1:08:34 GMT
Leo If I read you correctly, you wanted to feed the 7805/7905 into JLH then back into PCB supply points ? If so, and you have a good stock of 7805/7905 it would be worthwhile seeing if you can find a couple with a little over 5V output to make up for some of the JLH loss of around 200mV (?) Alex Using the Kumisa's 7815 and 7915 regs then yes, it would make things a lot more convenient
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Post by pagan on Jan 20, 2008 1:09:58 GMT
[quote author=leo It uses 6800uf + inductor+6800uf+inductor +6800uf on each rail
I'm thinking of tthe best way to fit the JLH to the Kumisa, was actually tempted to cut the tracks on the onboard 78/79 regs and add the JLH on the output there rather than adding another rectifier LM317/337 separate[/quote]
For the CRC or CLC I was thinking of just cutting the track between the two large caps.
For the JLH. I removed the standard psu components. Separated psu (LM317/337 and variable), then to JLH, then feed to power rail holes. Used the holes from the removed 78/79's Centre earth on CK2 to star earth and centre earth from JLH to same star earth.
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leo
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Post by leo on Jan 20, 2008 1:11:34 GMT
Who is going to be first to try to make a small JLH with a 7805 integrated , instead of a current limiter. Should only need a diode across IN and OUT of 7805 for added protection ? Alex Already done, or close enough? www.headphoneamp.co.kr/bbs/zboard.phpkumisa III in a mint tin!!! I can't get the link to work
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Post by Deleted on Jan 20, 2008 1:24:16 GMT
I wonder how the 2SC5171/2SA1930 would go there ? I am using these in the O/P of my preamp and PC headphone amplifier. I think Allan likes these too ? They are arse about too.
They are available from W.E.S. in Sydney too. Alex
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Post by leo on Jan 20, 2008 1:26:43 GMT
I wonder how the 2SC5171/2SA1930 would go there ? They are available from W.E.S. in Sydney too. Alex Thats awkward for me mate soon as I can find some local I'll compare and let you know
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Post by pagan on Jan 20, 2008 1:28:20 GMT
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Post by Deleted on Jan 20, 2008 1:32:11 GMT
Leo That was mainly for the benefit of dc and Allan. Those other devices may be hard to get Downunder. The 2SC5171/2SA1930 also have better HFE, and wider bandwidth. Alex
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Post by pagan on Jan 20, 2008 1:43:23 GMT
I wonder how the 2SC5171/2SA1930 would go there ? They are available from W.E.S. in Sydney too. Alex Thats awkward for me mate soon as I can find some local I'll compare and let you know If you can find the originals 2SB1186/2SD1763 hjem.get2net.dk/bencar/kumisa/k3/KumisaIII_headwize.htmli used the 2SB/2SD's in the headphone amp, why because i had them spare. and the 2SA/2SC's in the preamp version The 2SA/SC's might be better spec's but audible. The 2SA/2SC and 2SB/2SD are available from WES 2SA/2SC also from ampslab. I change most 78/79's for LM's for audio(analogue) where i can. An extra plus is they're adjustable.
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Post by leo on Jan 20, 2008 1:59:16 GMT
Thanks guys, I;ve had these 2SC4382/2SA1668 years, they was matched pairs from Audiolab in the UK (it no longer exists) I was repairing an Audiolab 8000 amp which had some blown parts
The sound of the Kumisa as standard is very smooth, vocals sound nice but the leading edges of acoustic sounds a bit soft
All electrolytic caps are Panasonic FM , these was recommended for this amp and they was quite cheap to buy, normally low ESR can be bright but they are far from it in this amp
I'm going to leave it running for burn in
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leo
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Post by leo on Jan 20, 2008 2:01:45 GMT
Thats awkward for me mate soon as I can find some local I'll compare and let you know If you can find the originals 2SB1186/2SD1763 hjem.get2net.dk/bencar/kumisa/k3/KumisaIII_headwize.htmli used the 2SB/2SD's in the headphone amp, why because i had them spare. and the 2SA/2SC's in the preamp version The 2SA/SC's might be better spec's but audible. The 2SA/2SC and 2SB/2SD are available from WES 2SA/2SC also from ampslab. I change most 78/79's for LM's for audio(analogue) where i can. An extra plus is they're adjustable. AMB should have fitted adjustable regs on the Kumisa, for the sake of a couple of added resistors and extra cap it should have made the better performance worth it
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Post by pagan on Jan 20, 2008 2:25:38 GMT
AMB should have fitted adjustable regs on the Kumisa, for the sake of a couple of added resistors and extra cap it should have made the better performance worth it Yes, it was mentioned at the time but he(AMB) had his own views. Not sure if i posted Martins work on them. www.acoustica.org.uk/Or ALW's ps Still waiting on the Fleas
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Post by leo on Jan 20, 2008 2:29:41 GMT
Acoustica.org is a good site, some nice reading on there
Just had another quick listen to the Kumisa, acoustics still a little smooth , midrange is rather good though
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Post by leo on Jan 20, 2008 3:52:05 GMT
I've cranked the bias from 14mV to 18mV, I like the sound better
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Post by Deleted on Jan 20, 2008 4:51:45 GMT
Getting closer to Class A ? ;D
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Post by pagan on Jan 20, 2008 4:52:25 GMT
I'm running mine at 25mV across 0.5ohm
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Post by leo on Jan 20, 2008 12:00:19 GMT
Me too now ;D Sound is even smoother with it this high, it may suit brighter cdp's better, leading edges are rounder
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Post by Deleted on Jan 20, 2008 12:21:10 GMT
Leo Is this with, or without the JLH in line ? Alex
BTW, Allan's Kumisa 3 vs. SC Class A preamp 10am tomorrow. Should be interesting. Allan is pretty good at fine tuning.
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Post by leo on Jan 20, 2008 12:34:53 GMT
Leo Is this with, or without the JLH in line ? Alex BTW, Allan's Kumisa 3 vs. SC Class A preamp 10am tomorrow. Should be interesting. Allan is pretty good at fine tuning. Just fitting some little heatsinks to the JLH's ready for trying ;D The standard 7815/7915 are getting much warmer now so hopefully this JLH will be ok Let us know how the shootout goes its all good fun
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Post by dc on Jan 20, 2008 13:42:29 GMT
wow, this thread very quickly got out of my depth
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Post by leo on Jan 20, 2008 17:55:41 GMT
Please join in DC, the thread wasn't meant to scare anybody off, if you have anything you want to know
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Post by Deleted on Jan 20, 2008 19:52:28 GMT
dc Sorry to confuse you with all the tech talk. The BIAS adjustment governs the minimum current through the output stage , and may be used to get further linearity from this stage, although at the expense of higher current draw. (simplified) The JLH that is referred to is a parallel type voltage regulator designed by the late John Linsley Hood. It is capable of reducing PSU noise and impedance to a much lower level than a conventional voltage regulator I.C. This usually results in a more neutral sounding frequency response, as well as helping with low level detail , soundstage etc. It also has a slow turnon, which can usually stop switchon thumps. Alex
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Post by jonclancy on Jan 24, 2008 14:00:41 GMT
I'll join in, if that's OK??? I'd like to use the JLH reg with my CK2III (almost finished) and also as a replacement for the 40VDC unregulated PSU for my Pass Labs Pearl phono stage. Just wondering if it was possible to configure the JLH for 40VDC? Nice work, Leo. I'm hoping to have some tunes from CK2III very soon! Cheers Jon PS Does it matter if I fitted polar Panny FCs instead of the specified bi-poloar 10uF 50V electrolytic caps on the CK2III? I've just noticed - must have overlooked that when doing my parts order from Farnell. Thanks!
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Post by leo on Jan 24, 2008 14:27:50 GMT
Of course its ok if you join in BTW use the alternative servo parts, you should have all those
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