FritzS
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Post by FritzS on Dec 19, 2007 9:12:02 GMT
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leo
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Post by leo on Dec 19, 2007 11:11:51 GMT
So the Borbely headphone amp uses 2SK389 for the input and 2SJ79/ 2SK216 or 2SJ313/ 2SK2013 for the output
Theres quite a lot of J-fets available but all the ones I've heard of are only low power like 2sk170 / 2SJ74 that come in a t0-92 package, for higher power T0-220 package mosfets are usually used
What sort of thing are you wanting to build Fritz?
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FritzS
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Post by FritzS on Dec 19, 2007 15:01:03 GMT
Today it's only a idea for 2008 - a headphone amp
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leo
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Post by leo on Dec 19, 2007 17:08:03 GMT
I just wondered so it would give us a better idea what to look for so we can help you out
Theres J-fets for the input stages and normally Mosfets for the output stage, tbh I have not seen a headphone amp that uses J-fets on the output
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pagan
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Post by pagan on Dec 21, 2007 4:12:34 GMT
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FritzS
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Post by FritzS on Dec 21, 2007 5:58:21 GMT
I search in "the market" before I will done My "old idea" is to make a tube-amp without tubes I think JFETs are the nearest like tubes
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leo
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Post by leo on Dec 21, 2007 11:28:26 GMT
Which one uses J-fet out?
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pagan
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Post by pagan on Dec 21, 2007 13:55:41 GMT
Sorry Leo J-fet's !! on ouputs, good point.
I have the two of CK2 version's of Benny's design. sounds good. Except no fet inputs, using BC's input and 2sa1930/2sc5171 outputs. One as headphone amp and the other as preamp. The preamp is also JLH'd, big improvement .
I have been thinking about a fet version of this headphone amp. Using 2sk170/2sj74 instead of BC550C/560C's "weel maybe one set of BC550C/560C's" And IRF9610/IRF610 for outputs. I know! Not J-Fets
The IRF's are overkill, IIRC, need to find something else.
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leo
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Post by leo on Dec 21, 2007 17:16:43 GMT
Thanks Pagan, what headphones do you use with the CK2? I'm also going to try the J-fets and BC's on the input, it should be worth comparing them, I'm looking forward to trying this unit tbh, the circuit looks decent, just hope its got the juice to drive my AKG's well.
Regarding JLH'd I presume you added JLH shunt regulation?
Be nice to get a few more CK2 owners on here so we can share idea's and post results
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pagan
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Post by pagan on Dec 22, 2007 1:38:17 GMT
Leo "what headphones do you use with the CK2?" I use beyerdynamic DT880's "I'm also going to try the J-fets and BC's on the input, it should be worth comparing them, I'm looking forward to trying this unit tbh, the circuit looks decent, just hope its got the juice to drive my AKG's well." Didn't try the J-Fet's on the input, available sources were i live are inconsistant eg 2sk170 by 10 = 5*BL + 2*GR and 3*whatever. a bit difficult to match. "Regarding JLH'd I presume you added JLH shunt regulation?" Yes the little circuit SandyK put me onto. Works well in a variety of places. The CK2 onboard psu is fairly basic, the two caps arn't even CRC connected, AMB wasn't interested, Benny's original was. Also the 7815/7915's not even 317/337's. It's worthy of a low noise psu. It should be ok with the AKG's (low impedance?) Reports at headwize are favourable. my suggestion is to use 2sa1930/2sc5171(reverse pinout) instead of the BD139/140's on outputs. Faster tranny, lower COB, better package for heat. Thermal couple all the outputs together (they don't need to be) you could also wind up the bias if you know what your doing ;D
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leo
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Post by leo on Dec 22, 2007 17:52:08 GMT
Pagan, AMB seems to charge a bit extra for matched J-fets so I'll probably have a few of those and then try the BC's. Thanks for the recommendation output transistors, I have some Hitachi 2sd669/2sb649 spare in my parts box which I might also try. This amp will be a piece of cake to build and set up compared to other projects I've had so will be interesting tweaking the bias. I had a feeling the JLH regs was the ones recommended by Alex I'll be fitting those in the Silicon chip 15watt class for regulating the long tailed pairs so may have to etch another extra board for the CK2 if it made a worthwhile improvement
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Post by Deleted on Dec 22, 2007 21:47:27 GMT
"I have the two of CK2 version's of Benny's design. sounds good. Except no fet inputs, using BC's input and 2sa1930/2sc5171 outputs."
Way to go ! ;D
Have fun Allan and Leo Will chip in when Optus sorts things out at other end All the best for Xmas and New Year Regards Alex
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leo
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Post by leo on Dec 22, 2007 23:02:49 GMT
"I have the two of CK2 version's of Benny's design. sounds good. Except no fet inputs, using BC's input and 2sa1930/2sc5171 outputs." Way to go ! ;D Have fun Allan and Leo Will chip in when Optus sorts things out at other end All the best for Xmas and New Year Regards Alex Same to you Alex and good luck mate!
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pagan
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Post by pagan on Dec 23, 2007 9:16:45 GMT
EEK Alex is back!!!!!!
I will take the CK2 for Alex to listen too, when it's suitable for him.
alex remmember Optus always say "yes". Pitty they don't do!!
All the best for Xmas and New Year
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pagan
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Post by pagan on Dec 23, 2007 9:58:10 GMT
Pagan, AMB seems to charge a bit extra for matched J-fets so I'll probably have a few of those and then try the BC's. Thanks for the recommendation output transistors, I have some Hitachi 2sd669/2sb649 spare in my parts box which I might also try. This amp will be a piece of cake to build and set up compared to other projects I've had so will be interesting tweaking the bias. I had a feeling the JLH regs was the ones recommended by Alex I'll be fitting those in the Silicon chip 15watt class for regulating the long tailed pairs so may have to etch another extra board for the CK2 if it made a worthwhile improvement Leo yes Alex's recommendation. the JLH works well. If you have a preamp too. The input pair on the CK2 do need to be matched, J-Fets or BC's BC's are easier (availability) Do use "C's" all and/or "BL's" for fets
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leo
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Post by leo on Dec 23, 2007 13:01:18 GMT
Pagan,
Are you using 2sa1930/2sc5171 for Q4/6 in the JLH regs for the CK2 ? Also do you use the higher voltage to the CK2 and lower voltage to the servo rather than +/-15v thats used on AMB's circuit?
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pagan
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Post by pagan on Dec 23, 2007 20:58:49 GMT
Leo The JLH is in the CK2 preamp at present. This JLH is all BC's. The CK2 preamp has the 2sa1930/2sc5171's(matched hFE) and lower gain(approx 4(dB), matched BC's inputs, the rest of the BC's are matched gain to within approx 5. and all BC's are "C"s
The CK2 headphone amp also has same matched BC's but matched 2sb1186/2sc1763's outputs. standard psu, Panasonic FC's for caps. headphone amp was built first, also with BD's, thats why no JLH yet. Just change BD's for the 2sa/2sc's a short time ago.
The JLH went in my modded CD67. Another then went into a SC100watt, +/-55v modded pcb for 2sa/2sc pinout and used 2sa1930/2sc5171's for Q6, 2sa970/2sc2240's for Q1/2 BD139/140 for Q4 and BC639/640 for Q3/5. Another for a modded SC20watt Class A (i like this amp)
Hmm need to etch some more pcb's, one for the headpone amp and i'll try one also for a VSPS riaa. Etching today.
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pagan
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Post by pagan on Dec 24, 2007 7:43:45 GMT
Pagan, Are you using 2sa1930/2sc5171 for Q4/6 in the JLH regs for the CK2 ? Also do you use the higher voltage to the CK2 and lower voltage to the servo rather than +/-15v thats used on AMB's circuit? 2sa1930/2sc5171 for Q4/6 are not necessary for the CK2 Used BD639/640's for the JLH'd preamp because easier to get. Standard LM317/337 adjustable psu to JLH then to CK2 at +/-15v. JLH drops less than 0.5v. Havn't needed to up the power yet, thought about +/-18v, havn't tried it, just havn't got around to it. edit forgot 2134 is good for +/-18v Front end stage on class AB with +/- 55v I used 2sa1930/2sc5171 for Q6 and BD139/140's for Q4, for power dissapation.
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leo
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Post by leo on Dec 24, 2007 12:08:48 GMT
Thanks Pagan, I'm looking forward to trying this thing out, be also interesting trying it as a pre and lowering the gain. Good thing about the BC's is that they are cheap so matching shouldn't be a problem.
I'll start a new thread building the CK2, probably build it as bog standard first and then add the JLH, use the alternative servo instead of the one using NP 10uf's.
Whats the current draw of the CK2? How do you find the JLH in the CD67? I might try them as pre regs for the PCM1794 and see how they compare against the ALW super regs
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pagan
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Post by pagan on Dec 24, 2007 14:16:52 GMT
Hi Leo This is the circuit of the output stage for the CD67 From the cd63/67 thread on diyaudio. home.quicknet.nl/qn/prive/ra.vdsteen/pdfs/CD_outputstage_PCB.pdfThurston's circuit, 6h5c(Ray) sim's and filter values, me modded a bit and used 2sk389's for input pair. (I still don't like matching 2sk170's) I used the JLH is for this part. Dac already using ALW superreg and Tent XO I think the ALW reg's might be better for the DAC, but it would be an interesting experient. I use the super reg's for things below 40mA anything above that say 40mA to a few hundred mA i use the JLH. I don't remember the current but probably around <100mA depending on bias
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leo
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Post by leo on Dec 24, 2007 14:53:35 GMT
I'm glad your on here Pagan that circuit of Rays you posted is something I'm going to try with the PCM1794, I was going to use passive I/V on my dacs output, remove that filtering on the input section to Rays circuit as this dac is different to the one used in the Marantz. Infact Ray has recently built the same PCM1794 dac I currently have, I went a little further with the regulation but his tent XO is the same I use Heres mine, I've added a few other bits and pieces now though, the ALW pre regs are in a separate case
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leo
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Post by leo on Dec 24, 2007 14:58:47 GMT
I'm also hoping to add a switch to enable bypass of the SRC, not sure if its a simple case of adding a switch to the bypass pin of the src4192 or if theres more involved Theres so many projects I want to try, its just having the time
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pagan
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Post by pagan on Dec 24, 2007 15:20:23 GMT
Leo Something about LM317/337's or when not to use a low impedance cap www.tnt-audio.com/clinica/regulators_noise2_e.htmlThe 78**/79**'s are worse. The src4192 should be easily bypassed with a switch. edited About the link on LM's I'm looking for another link discussing inductance issues with LM317/337's and low impedance output caps. Think it was done by ALW. will post when i find it.
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leo
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Post by leo on Dec 24, 2007 15:52:33 GMT
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Post by Deleted on Dec 25, 2007 21:54:51 GMT
"I normally use a low ESR on the adjust pin and a tant on the output pin"
YUK ! With analogue a 100uF Elna Starget would be nice. For the adjust, a tantalum or low ESR will exaggerate the treble, I found the latter with the Class A PSUs.
Back to the cleanup and moving ! Regards Alex
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