Thanks Gabor, please keep me posted!
Are these kits foolproof, can I assemble and play or do I need to test it, set bias (bias?) etc first? If I do, I have a freind whos built Amps before, maybe he can help.
Can anyone reccomend a suitable power supply, preferrably some kind of kit? And where do I get a nice chassis from?
Mike
Are these kits foolproof, can I assemble and play or do I need to test it, set bias (bias?) etc first? If I do, I have a freind whos built Amps before, maybe he can help.
Can anyone reccomend a suitable power supply, preferrably some kind of kit? And where do I get a nice chassis from?
Mike
HI Mike
For Q5 use TIP41C on the heat sink with wire .Follow the schematic not the board .
Look up the legs of the TO220 transistor and with 3pc of wire connect into the place of Q5 .
Don't forget to connect the input ground to the main ground with out the amp is not working at all .
Regards
For Q5 use TIP41C on the heat sink with wire .Follow the schematic not the board .
Look up the legs of the TO220 transistor and with 3pc of wire connect into the place of Q5 .
Don't forget to connect the input ground to the main ground with out the amp is not working at all .
Regards
HI
For Q5 use TIP41C on the same heat sink were you mount the power transistors , inportant !
Use 3PC of wire and simple connect it to the PC board for Q5.
Please look up on the net TO220 case because TIP41C is in TO220 case and follow the schematic not the mark on the PC board .
For power supp I use 4pc 41 000 Mepco 50V capacitor and 2 transformer 27.5--0--27.5 265VA each which give +/-40 after rectifier.
Regards
For Q5 use TIP41C on the same heat sink were you mount the power transistors , inportant !
Use 3PC of wire and simple connect it to the PC board for Q5.
Please look up on the net TO220 case because TIP41C is in TO220 case and follow the schematic not the mark on the PC board .
For power supp I use 4pc 41 000 Mepco 50V capacitor and 2 transformer 27.5--0--27.5 265VA each which give +/-40 after rectifier.
Regards
This amp is brilliant
I have just finished assembling a pair of these amps into a case with a decent pair of unregulated psus. I can tell you these amps rock - deep tight base, controlled mid-range and sweet highs. I have a pair of lm3875 amps and the nap 140 clones beat them. I also have a pair of JLH 75W amps and these are as good - maybe better when they are run in. If you are undecided, don't wait any longer - build a pair.
I have just finished assembling a pair of these amps into a case with a decent pair of unregulated psus. I can tell you these amps rock - deep tight base, controlled mid-range and sweet highs. I have a pair of lm3875 amps and the nap 140 clones beat them. I also have a pair of JLH 75W amps and these are as good - maybe better when they are run in. If you are undecided, don't wait any longer - build a pair.
A dumb question for you all.
Fitted with a 40VDC dual rail power supply, what is the rated output? I have heard from 60 to 120 wpc at 4 ohm. Can someone verify the output?
Is 40VDC max voltage for this kit? And is it for max voltage for 8 ohm or 4 ohm? I have many 600VA toroids that are 40-0-40 (+/-56VDC), but would have to buy a 28VAC for the required 40VDC supply. Any advice on VA rating too?
Got my kit, unfortunately moving across the US in a few days, so she's all packed away.
Looking forward to see what she can do against my Krell KSA-50 Clone, UCD400, ESP P101, Aleph 60 (still not done yet), a panny XR45, and a few LM3886 Gainclones.
Fitted with a 40VDC dual rail power supply, what is the rated output? I have heard from 60 to 120 wpc at 4 ohm. Can someone verify the output?
Is 40VDC max voltage for this kit? And is it for max voltage for 8 ohm or 4 ohm? I have many 600VA toroids that are 40-0-40 (+/-56VDC), but would have to buy a 28VAC for the required 40VDC supply. Any advice on VA rating too?
Got my kit, unfortunately moving across the US in a few days, so she's all packed away.
Looking forward to see what she can do against my Krell KSA-50 Clone, UCD400, ESP P101, Aleph 60 (still not done yet), a panny XR45, and a few LM3886 Gainclones.
I am also reading that with the 40V rails, the max recommended bias is 6.6mv max, which is 30ma current through the output transistor. With this bias, the dissipation to the sink is only 4.8watts.
If this is correct, theres not much sinking required (someone check my work please).
Is there anyone who has biased these kits higher? I am not going to say bias it into class A, but could this amp sound better with more bias current?
I would think most components in this kit would be able to handle quite a bit more than 30ma.
If this is correct, theres not much sinking required (someone check my work please).
Is there anyone who has biased these kits higher? I am not going to say bias it into class A, but could this amp sound better with more bias current?
I would think most components in this kit would be able to handle quite a bit more than 30ma.
Hello
John65b please I'm waiting on you to finish the Naim clone ad com pared to the Krell KSA-50 amplifier .
I want to know if the Krell come close to the Naim clone or may be better ? , if it wort to give a try or not .Of course is very important what kind of parts you use on the board and on the power supp.
You know easier to sell the populated board if not fired up .
People does not think you sell it because is a bad amp .
Even I have all the parts for the KSA-50: 1000A toroid Plitron brand new and very large case all made out from all heat sink was design to the KSA 100 Clone . I want to hear from you which amp sound better .
Some people said the Symasym beat the Krell clone , I build it with good components and for me it was just a waste of money .
Regards
John65b please I'm waiting on you to finish the Naim clone ad com pared to the Krell KSA-50 amplifier .
I want to know if the Krell come close to the Naim clone or may be better ? , if it wort to give a try or not .Of course is very important what kind of parts you use on the board and on the power supp.
You know easier to sell the populated board if not fired up .
People does not think you sell it because is a bad amp .
Even I have all the parts for the KSA-50: 1000A toroid Plitron brand new and very large case all made out from all heat sink was design to the KSA 100 Clone . I want to hear from you which amp sound better .
Some people said the Symasym beat the Krell clone , I build it with good components and for me it was just a waste of money .
Regards
70 wpc @ 4 Ohm? 8 ohm?
Gaborela
As far as the Krell, mine sounded lame after I first built it. I couldn't believe what everyone was saying about the amp. It sounded dull and lifeless.
When I was trimming the DC offset, I noticed I couldn't get one of the amp channels to drop below 350mv, no matter how much I turned the pot. The other channel was able to get to 0mv, but it wandering all over the place, and needed to be reset every time I fired up the amp.
It was then I noticed that I did not have the signal grounds connected to the power ground on the board. I connected the grounds, and the DC Offset of both channels easily trimmed to 0mv. I set the bias at 650mv (1A).
I then listened, and have been smiling ever since. Best I have by quite a margin. I may be interested in your boards if you decide to sell them.
A pic attached of the Krell "guts". Just as you say - 4 heatsinks making up the chassis.
Attachments
hoka said:
If R35 went up in smoke (and flame I assume, FUN!) you will have to replace R29 (big power resistor) and likely the output transistors as well.
Replace R35 and R26 first. Measure across R32 (no power on the circuit) if you get a stable reading around 31-32R then you've blown your output transistors. If the reading slowly rises to 4-6k then the output trans. are okay. If the o/p trans are blown, good luck finding the SanKens. Digikey carries the Toshiba 2sc5200 that are TubeHunter's current spec, but your should replace all four (both boards).
hoka said:
It will rise slowly to around 4K7 but then holds a charge so if you check again after a few seconds it will still read over 4k.
Sounds good. Did you run jumpers from signal ground (SG) to the ground tap near the SanKens? (GND) I would check the orientation of the Q1, Q2, Q5 again. If they are the 2N5551 then they go in opposite of the marking. It seems like TubesHunter shipped kits with different transistors here so check which you have and look up the pin orientation (CBE) on the manufacturer's website. One last thing to do because it is not too much trouble is to remove the trimmer pot and check to make sure it is adjusted to the middle of its range (1K1 on either side).
Other than that, the 2N5551's are about $.08 each so you could replace them all for less than $1 USD. Might not be a bad idea if they were powered up in the wrong orientation.
BTW- where did you find replacement SanKens?
I see there are currnetly two different kits available (both with blue PCB's). Which is the preferred version?
Short, Wide Version
Or the Long, Narrow Version
IIRC the second version is the one with the reversed transistor markings on the PCB. Any comments or opinions are welcome.
Short, Wide Version
Or the Long, Narrow Version
IIRC the second version is the one with the reversed transistor markings on the PCB. Any comments or opinions are welcome.