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krell ksa5 klone


kevin gilmore

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  • 2 weeks later...

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. 

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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!

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  • 4 weeks later...

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 by nopants
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  • 2 weeks later...

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 by kevin gilmore
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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 by kevin gilmore
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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.

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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 by kevin gilmore
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