nopants Posted July 30, 2013 Report Posted July 30, 2013 Any recommendations as far as what supply voltage, etc. to build one for potential use with the k1000? my intention is to build the balanced version, but I'm indifferent if single-ended is sufficient for these headphones.
fordgtlover Posted July 30, 2013 Report Posted July 30, 2013 Not really, no. It's well within spec. Thanks
spritzer Posted July 30, 2013 Report Posted July 30, 2013 Stick with the stock supply voltages. No sense increasing them.
Headampbro Posted August 7, 2013 Report Posted August 7, 2013 May I know is there anymore board left for me to order??
nopants Posted August 7, 2013 Report Posted August 7, 2013 Sorry to add to the broken record playlist, but do the devices/channels require some sort of matching?
Headampbro Posted August 8, 2013 Report Posted August 8, 2013 Anyone can help me verify it, does the headphone jacks can be used and drive concurrent simultaneously?? If so, does it mean both channels are sharing the power to drive each one of total four drivers??
spritzer Posted August 8, 2013 Report Posted August 8, 2013 You are talking about the production amp here then? Doesn't matter really as it is the same case with all amps that feature multiple outputs, there are just two channels in the amp so power will be shared. Sorry to add to the broken record playlist, but do the devices/channels require some sort of matching? Matching is better but it should work just fine with no matching at all.
VPI Posted August 8, 2013 Report Posted August 8, 2013 It appears my 71-CPF3-F-2 Vishays are back ordered until October. Is there something else recommended that I might find more expediently to act in their place? Thanks.
alexcp Posted August 9, 2013 Report Posted August 9, 2013 Hello, Another build in progress: The amp proper is built (see photos) and tested; the sound with Grado GS is wonderful! Thank you Kevin for sharing the design! No power supply yet; I use my desktop lab supply for now The caps are Samwha RD; perhaps not in the spirit of the thread, but I just had them The output transistors are D44H11 and D45H11 (I could not match MJFs, so I used what I could match; had to add some insulation though) Resistors are RN55/RN60 and Panasonic ERX3 No case yet, plan to use one from modushop/HIFI2000 Question: I want to use a high resistance volume control pot (50k or 100k). Would it be ok to increase the resistance between the gate of the input JFET and the ground so as not to load the pot too much? What would be a practical limit on this? 1Meg? Thank you!
kevin gilmore Posted August 9, 2013 Author Report Posted August 9, 2013 You can probably change R36 to 100k. If you go any higher you might have to change C1 a bit. You can probably leave everything alone and use a 50k pot.
nopants Posted September 2, 2013 Report Posted September 2, 2013 (edited) Went ahead and populated the psu BOM at Mouser - http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=e580be76a8 , can you guys see it? I think I may have gotten some counts/values wrong, I definitely added extra for a few caps at the very least, etc. What would you need to change the diodes and resistors to to get a different rail supply, such as +/- 35 like what Kevin mentioned? Edited September 2, 2013 by nopants
fordgtlover Posted September 5, 2013 Report Posted September 5, 2013 I can't see anything missing from the BOM. The counts seem fine, except for the caps as you pointed out.
kevin gilmore Posted September 16, 2013 Author Report Posted September 16, 2013 (edited) here is the bom for the dual zener regulated power supply less the heatsink which i'm too lazy and tired to look up at the moment. the hole sizes for the zeners are going to be a bit tight. will be fixed on the next rev of the board old power supply 1000uf/35v 871-B41041A7108M000 8 4700uf 50v ls10mm 35 dia 598-SLP472M050C5P3 2 1n4750 512-1N4750ATR 2 1n4748 512-1N4748ATR 2 mfj15030 863-mjf15030g 4 mjf15031 863-mjf15031g 4 bridge rectifier 625-G3SBA20-E3/51 2 750 ohm 71-rn60d-f-750 2 562 ohm 71-rn60d-f-562 2 3 pin terminal 651-1729131 2 2 pin terminal 651-1729128 2 Edited September 16, 2013 by kevin gilmore
fordgtlover Posted September 16, 2013 Report Posted September 16, 2013 (edited) Thanks, Kevin. I think we also need 4 x 0.1uf film capacitors (80-R82EC3100DQ70J) Edited September 16, 2013 by fordgtlover
spritzer Posted September 16, 2013 Report Posted September 16, 2013 Most excellent as I just got way too many of these boards.
kevin gilmore Posted September 16, 2013 Author Report Posted September 16, 2013 (edited) moar better now old power supply 1000uf/35v 871-B41041A7108M000 8 4700uf 50v ls10mm 35 dia 598-SLP472M050C5P3 2 1n4750 512-1N4750ATR 2 1n4748 512-1N4748ATR 2 mfj15030 863-mjf15030g 4 mjf15031 863-mjf15031g 4 bridge rectifier 625-G3SBA20-E3/51 2 750 ohm 71-rn60d-f-750 2 562 ohm 71-rn60d-f-562 2 3 pin terminal 651-1729131 2 2 pin terminal 651-1729128 2 .1uf ls 5mm 80-R82EC3100DQ70J 4 heatsink 532-529902b25g 4 thermal washers 8 new power supply 220uf 50v ls 5mm dia 10mm 647-UPW1H221MPD 4 bridge rectifier 625-G3SBA20-E3/51 2 10 ohm 71-rn60d-f-10 1 100 ohm 71-rn60d-f-100 2 511 ohm 71-rn60d-f-511 2 750 ohm 71-rn60d-f-750 2 1k ohm 71-rn60d-f-1.0k 2 2k 71-rn60d-f-2.0k 4 10k 71-rn60d-f-10k 2 op27 use something else 2 4.7uf 505-MKS24.7/63/5 2 3 pin terminal 651-1729131 1 2 pin terminal 651-1729128 2 mfj15030 863-mjf15030g 1 mjf15031 863-mjf15031g 1 zener 13v .5w 78-BZX55B13-TAP 2 lm4040-2.5 926-LM4040DIZ25NOPB 2 .1uf ls .1 too lazy to look up 2 mj15024 863-MJ15024G 1 mj15025 863-MJ15025G 1 pnp mpsw56 1 npn mpsw06 1 heatsink 532-568303B00 2 thermal washer 739-A15038003 2 Edited September 17, 2013 by kevin gilmore
seroxatmad Posted September 20, 2013 Report Posted September 20, 2013 Hi I am in the UK and have the option of the LSK389 in a,b,c and d options from a UK source? The data sheets look identical and the prices are all similar - what version do you think is the best? Cheers John
luvdunhill Posted September 20, 2013 Report Posted September 20, 2013 Hi I am in the UK and have the option of the LSK389 in a,b,c and d options from a UK source? The data sheets look identical and the prices are all similar - what version do you think is the best? Cheers John There was an article in AudioXpress a while back that noted the A to be lowest noise if you do not need the higher Idss.
nopants Posted September 20, 2013 Report Posted September 20, 2013 I can't believe trendsetter charges 20$ for shipping, I ordered direct from linear when I got my kgsshv parts- I believe they're about 6 a piece that way. I'm also local so that cut down on shipping. Have to order over the phone but that's a small barrier.
kevin gilmore Posted September 21, 2013 Author Report Posted September 21, 2013 (edited) there is a grounding error on the zener power supply on the final output cap on the minus power supply. the wrong side of this cap is grounded causing the minus supply to be grounded. simple fix, use a drill bit on the top to un-ground the grounded hole, then add a jumper on the bottom to the other side of the cap to the other cap to ground. http://gilmore.chem.northwestern.edu/dsc_0469.jpg http://gilmore.chem.northwestern.edu/dsc_0470.jpg Edited September 21, 2013 by kevin gilmore
kevin gilmore Posted September 24, 2013 Author Report Posted September 24, 2013 both supplies now fully tested and i'm really happy with each of them. the bigger one easily does 1 amp, so enough to run a pair of boards for balanced. http://gilmore.chem.northwestern.edu/krellsupplies.jpg
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