leo
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Post by leo on Dec 26, 2007 1:11:17 GMT
I'll take that advice with the SC classA's as you've played with these more than me With the ALW super regs I've found nothing that comes close to the Rubycon ZA's and tants, it was recommended stargets with those but they never worked as well as tants and ZA's IMO Only standard regs I use are on the 3.3v in the PCM1794 dac, polymer are the best I've tried in that. Once I get the other regs for the classA's etched I'll use Stargets seeing as though they work well with those and have a few spare Good luck on the sort out Alex!
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Post by Deleted on Dec 26, 2007 23:28:04 GMT
Leo I find that in general, tantalums on the adjust terminal of an adjustable VREG cause a small amount of HF accentation. Where they work well as bypasses etc ,is in tape decks etc to improve channel separation, or where treble detail may be slightly lacking.Tantalums sometimes go s/c for no apparent reason, although later types are reputed to be more reliable. BTW, those ATH W1000 are quite superb. Still no Internet at new house. Have you been game to try the xmas tree lights into the TLs ? Alex
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leo
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Post by leo on Dec 27, 2007 0:34:17 GMT
Leo I find that in general, tantalums on the adjust terminal of an adjustable VREG cause a small amount of HF accentation. Where they work well as bypasses etc ,is in tape decks etc to improve channel separation, or where treble detail may be slightly lacking.Tantalums sometimes go s/c for no apparent reason, although later types are reputed to be more reliable. BTW, those ATH W1000 are quite superb. Still no Internet at new house. Have you been game to try the xmas tree lights into the TLs ? Alex I only use a tant on the output pin, lytics for the rest of the decoupling after that, polymer or a ZA on the adjust pin Pleased to hear your liking those AT's Soon as the Christmas tree is packed up the big beasts will be rigged up to the lights instead;) I'm hoping it'll be ok with the output of the dac running straight on the input and using the remote adjustable SPDIF output of the Oppo I've got a lot to try once I can get some etching done
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leo
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Post by leo on Dec 27, 2007 0:41:18 GMT
I'm actually looking forward to trying the tree lights as a headphone amp too
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pagan
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Post by pagan on Dec 27, 2007 8:42:11 GMT
Leo For the JLH on the CK2 use SandyK's values for current limiter ie 1.2ohm and 1k8 ~500mA BC639/640 handle it ok.
Standard with 6R8 100mA etc wasn't stable +/-15v on amp. was ok in psu out with JLH connected untill i connected to CK2. then +/-15v line would swing between 10v to 15v slowly.
Grd from JLH output to star earth. centre earth on CK2 to star earth.
The JLH works well on the CK2 Better definition and sustain on individual notes. Still very musical amp.
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leo
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Post by leo on Dec 27, 2007 13:20:16 GMT
Pagan, Thank you
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Post by Deleted on Dec 28, 2007 20:40:44 GMT
"Leo For the JLH on the CK2 use SandyK's values for current limiter ie 1.2ohm and 1k8 ~500mA BC639/640 handle it ok. Standard with 6R8 100mA etc wasn't stable +/-15v on amp. was ok in psu out with JLH connected untill i connected to CK2. then +/-15v line would swing between 10v to 15v slowly." Leo I find it's always better to have a much higher current limit than necessary. Not only does it give a faster startup, but less chance of "hunting' Always read the output voltages with load connected. The readings shouldn't show any evidence of "hunting" With higher current loads, the bias resistor of the current limiter may need to be decreased slightly in value if this happens. The BC639/BC640 seem to vary quite a bit in their VCE saturation voltage. Alex BTW, still waiting Internet etc at new address. Allan Thanks for helping out.
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leo
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Post by leo on Dec 28, 2007 21:53:06 GMT
Thanks guys, its nice asking somebody else best way to try something for a change seeing as both of you have built a few of the JLH's I've had a look on farnell for the BC639/640's, they don't seem to do pairs from the same manufacturer
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pagan
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Post by pagan on Dec 28, 2007 23:26:52 GMT
I've had a look on farnell for the BC639/640's, they don't seem to do pairs from the same manufacturer I'm not quite sure if this matters!! I got my BC639/640's from Jaycar, and they cheap generic "run of the mill stuff" For the BC549/559C's, I used 550/560C's why? Jaycar had BC549C's but the BC559 were not "C"'s, not even "B"s or "A"s So I used the 550C/560C's that i couldn't match for previous project that had very high gain's.
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leo
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Post by leo on Dec 29, 2007 0:24:35 GMT
I've had a look on farnell for the BC639/640's, they don't seem to do pairs from the same manufacturer I'm not quite sure if this matters!! I got my BC639/640's from Jaycar, and they cheap generic "run of the mill stuff" For the BC549/559C's, I used 550/560C's why? Jaycar had BC549C's but the BC559 were not "C"'s, not even "B"s or "A"s So I used the 550C/560C's that i couldn't match for previous project that had very high gain's. Just me being picky
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FritzS
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Post by FritzS on Dec 29, 2007 15:05:34 GMT
"Leo For the JLH on the CK2 use SandyK's values for current limiter ie 1.2ohm and 1k8 ~500mA BC639/640 handle it ok. Standard with 6R8 100mA etc wasn't stable +/-15v on amp. was ok in psu out with JLH connected untill i connected to CK2. then +/-15v line would swing between 10v to 15v slowly." Leo I find it's always better to have a much higher current limit than necessary. Not only does it give a faster startup, but less chance of "hunting' Always read the output voltages with load connected. The readings shouldn't show any evidence of "hunting" With higher current loads, the bias resistor of the current limiter may need to be decreased slightly in value if this happens. The BC639/BC640 seem to vary quite a bit in their VCE saturation voltage. Alex BTW, still waiting Internet etc at new address. Allan Thanks for helping out. Sandy - have I overlooked - where is the link to this schema?
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leo
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Post by leo on Dec 30, 2007 21:11:18 GMT
"Leo For the JLH on the CK2 use SandyK's values for current limiter ie 1.2ohm and 1k8 ~500mA BC639/640 handle it ok. Standard with 6R8 100mA etc wasn't stable +/-15v on amp. was ok in psu out with JLH connected untill i connected to CK2. then +/-15v line would swing between 10v to 15v slowly." Leo I find it's always better to have a much higher current limit than necessary. Not only does it give a faster startup, but less chance of "hunting' Always read the output voltages with load connected. The readings shouldn't show any evidence of "hunting" With higher current loads, the bias resistor of the current limiter may need to be decreased slightly in value if this happens. The BC639/BC640 seem to vary quite a bit in their VCE saturation voltage. Alex BTW, still waiting Internet etc at new address. Allan Thanks for helping out. Sandy - have I overlooked - where is the link to this schema? I don't think its available online, if you PM me your Email I'll forward you the article , I presume thats ok guys?
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Post by Deleted on Dec 30, 2007 23:02:08 GMT
"I don't think its available online, if you PM me your Email I'll forward you the article , I presume thats ok guys?"
Leo Thanks Alex
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FritzS
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Post by FritzS on Dec 31, 2007 11:12:55 GMT
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Post by FritzS on Dec 31, 2007 14:25:40 GMT
Did you mean with "CK2" the "Cavalli-Kan Kumisa III Stereo Headphone Amplifier"? An interested game "green Solo" vs. "CK2" vs. "The 15w classA" modified as pre/headphone amp Have anyone build the "The 15w classA" as pre/headphone amp with reduced +- 15V voltage?
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leo
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Post by leo on Dec 31, 2007 15:03:54 GMT
I'm trying both amps Fritz, CK2 (KumisaIII) and the 15w classA. A forum member very kindly sent me the classA modules to try with all the mods implemented all I need to get them finished is the JLH regs and another main psu reg board. Soon as I get the CK2 I'll start a new thread on the build process
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leo
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Post by leo on Dec 31, 2007 19:45:25 GMT
started etching the JLH boards, these are taking a long time so i think I'm ready for some fresh Ferric chloride, I've had this stuff a while
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Post by Deleted on Dec 31, 2007 22:38:31 GMT
"Have anyone build the "The 15w classA" as pre/headphone amp with reduced +- 15V voltage? " Friedrich I am using a preamplifier based on that circuit, but scaled down for +-15V operation. It can drive a 75R load very nicely as well, and makes an excellent headphone amplifier. Photo was put in that section of home brew stuff some time back Alex.
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Post by Deleted on Dec 31, 2007 22:41:22 GMT
Leo Did you try heating the solution ? BTW, that PCB looks vaguely familiar ! Alex
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leo
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Post by leo on Dec 31, 2007 22:53:48 GMT
Leo Did you try heating the solution ? BTW, that PCB looks vaguely familiar ! Alex Hi ya Alex, hows the moving going? what I do is put the bowl of etching solution into a bucket of warm water so it floats on the top keeping the ferric chloride warm. Its had a lot of use though so its ready for changing anyway, its gone very dark in colour now "The pcb looks familar" it bloody well should do seeing as though its based on the file you sent me Anyway finally all boards are etched! just need drilling and stuffing then I'm ready to go
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Post by Deleted on Dec 31, 2007 23:58:31 GMT
Leo The move is going slooooooowly.I may have to extend to 26/1 from 12/01. Part of the problem is also school holidays, which means one has to stay behind to look after the kids, so can't really get stuck into the old place properly. Unfortunately the new place is > 30minutes drive each way from the old. (my son chose the new place !) It's amazing how much crap you collect ! Last time >6 years ago I got rid of some stuff that I later regretted. You probably can't get away with it, but I float the PCB container on top of very hot water in the kitchen sink. Only kidding about that amateurish PCB design ! Alex
BTW, BD139 and BD140 with HFE > 100 are quite good for the JLH current limiters. BC639 and BC640 with that kind of initial inrush current may eventually fail. No problems with lower current versions though.
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leo
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Post by leo on Jan 2, 2008 1:56:11 GMT
Leo The move is going slooooooowly.I may have to extend to 26/1 from 12/01. Part of the problem is also school holidays, which means one has to stay behind to look after the kids, so can't really get stuck into the old place properly. Unfortunately the new place is > 30minutes drive each way from the old. (my son chose the new place !) It's amazing how much crap you collect ! Last time >6 years ago I got rid of some stuff that I later regretted. You probably can't get away with it, but I float the PCB container on top of very hot water in the kitchen sink. Regarding the crap that gets collected up I get the same problem here, I can spend a day emptying the garage/workshop out and a month later it looks like a flea market! At least if your new place is bigger you get more room to spread it all out I agree though that the timing for the move was not exactly ideal for you though, anyway good luck!
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leo
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Post by leo on Jan 2, 2008 1:59:02 GMT
Leo Only kidding about that amateurish PCB design ! Alex Did you draw it out? it looks ok to me, I could have made it half the size using mainly SMD resistors etc but couldn't be arsed this ones been tried and tested so thats good enough for me BTW, BD139 and BD140 with HFE > 100 are quite good for the JLH current limiters. BC639 and BC640 with that kind of initial inrush current may eventually fail. No problems with lower current versions though. Ok taa, I think I'll just stick with the BD's then rather than the BC639/640, I'm just sorting out a BOM from Farnell
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leo
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Post by leo on Jan 2, 2008 2:16:51 GMT
BTW Alex, did you fit the JLH's on the 15w classA's main regulators outputs or did you fit separate LM317/337 ones?
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pagan
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Post by pagan on Jan 2, 2008 11:19:57 GMT
BTW Alex, did you fit the JLH's on the 15w classA's main regulators outputs or did you fit separate LM317/337 ones? Leo just incase SandyK's busy The pic's i've seen from the 15watt amp Two reg's, standard high current one feeds both channel's just outputs. The other reg is normal LM3*7's feeds front end(both channels) of amp via a JLH. not dual mono. Not quite sure if you need dual mono...... With the JLH on low power front ends. I did experiments with a SC100watt amp, Standard was +/-55v single LM3*7's based reg for the front end. Put a single modded JLH in, after the reg/before the front end. Used a crow, to test the JLH and looking for differences. Noise and channel crosstalk was easily picked up before the JLH but after the JLH was less than 1mv p-p. (below my crow capabilities) SandyK... that was the only thing done to that amp the group listened too, no matching bog standard. If you already use dual mono configuration, then a JLH per channel is easier to implement for the front end. Whether it's necessary? ?? My preamp, headphone amp'CK2's", CDplayer "CD67" all single. SC20+ running dual mono with a JLH per channel. So to answer a question? hmmmm!!!?
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