HI
Of course , tomorrow I will have to take a part the another side to do the ground and I will share the transistors what I use .
I read on the net somewhere somebody made different tests used different type of transistor and he said only with these transistors worth to build these amp .
The sound far better than any another transistors he tried .
I changed all the small capacitors silver mica , Wima and one Philips you can see on the picture .
On the input I use bipolar BG capacitor .
For the power supply I use 2pc toroid 275VA each and 27.5--0---27.5VAC
Four Mepco 41 000 capacitors .
Tomorrow more info!
Greetings .
Of course , tomorrow I will have to take a part the another side to do the ground and I will share the transistors what I use .
I read on the net somewhere somebody made different tests used different type of transistor and he said only with these transistors worth to build these amp .
The sound far better than any another transistors he tried .
I changed all the small capacitors silver mica , Wima and one Philips you can see on the picture .
On the input I use bipolar BG capacitor .
For the power supply I use 2pc toroid 275VA each and 27.5--0---27.5VAC
Four Mepco 41 000 capacitors .
Tomorrow more info!
Greetings .
Wow, Good deal. Every now and then I surprise myself.
"Even a blind squirrel gets an acorn every now and then."
It was a stab in the dark. Had a very similar problem on a Adcom GFA 555 and a DIY Krell KSA-50 Clone. You probably have a bad solder joint somewhere, as it should work fine without the ground jumper.
I may just buy a Naim kit now... Have a few 2SC5200/2SA1943 trannies left over from my Krell Clone KSA-50 project (excellent amp btw)
"Even a blind squirrel gets an acorn every now and then."
It was a stab in the dark. Had a very similar problem on a Adcom GFA 555 and a DIY Krell KSA-50 Clone. You probably have a bad solder joint somewhere, as it should work fine without the ground jumper.
I may just buy a Naim kit now... Have a few 2SC5200/2SA1943 trannies left over from my Krell Clone KSA-50 project (excellent amp btw)
Hello
I just ordered the second set Naim PC board using upgraded resistors Riken , all BG capacitors and my ON semi driver and power transistors .
I believe after I heard these amp is worth to try an total upgraded version .
I have the stuffed PC board for the Krell KSA 50 but it will goes to the Ebay .
I have an AlephX power amp so I don't think the Krell KSA clone it would come close to the AlephX sound or to the Naim Clone sound .
I'm a Naim clone fan now .
Regards
I just ordered the second set Naim PC board using upgraded resistors Riken , all BG capacitors and my ON semi driver and power transistors .
I believe after I heard these amp is worth to try an total upgraded version .
I have the stuffed PC board for the Krell KSA 50 but it will goes to the Ebay .
I have an AlephX power amp so I don't think the Krell KSA clone it would come close to the AlephX sound or to the Naim Clone sound .
I'm a Naim clone fan now .
Regards
I would give the Krell a shot before you dismiss it. I really like mine. It bounced my home brew 6L6/6SN7 Tube amp, ESP P101, UCD180 and UCD400, a Bel Canto S300 (ICEPower based), a few Gainclones, and a TA3020 Tripath based amp to the curb. I have an Aleph 60 pcb stuffed, just need to bolt onto the heatsinks and install into the chassis...I have high expectations on the Aleph 60, but doubt it will best the Krell...
I am intrigued with the Naim. I have enough of the parts to build one, unfortunately, I am in the middle of a cross country move (SLC Utah to Chicago).
Ahh what the hell. I will pick up a PCB tonight.
I have just completed my NAP140 KIT. It is latest version. Q1 & Q2 are BC546B and output transistor is TOSHIBA 2SC5200. Tested by regulated +/-40VDC. It is working properly. I set the bias at 20mA (4.5mV / 0.22 ohm) per output transistor and DC offset is around 27mV. The voltage drop of R21 is 0.635V, R6 is 0.588V, R10 is 8.65V and R18 is 0.596V.
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Damn!
Well, it's my own fault for being hasty. I blew up two 140c boards because of the reversed Q1, Q2, Q5. On one R35 caught fire (exciting!) this was my first clue that something was wrong. The other board didn't catch fire but was putting out 24v at the output.
I looked over this thread and saw that someone got a message from TubesHunter about the transistors being marked wrong on the boards. Too bad I didn't get that message. But I really should have thoroughly looked through the schematic.
If I replace all the transistors (and R35 of course) do you think the beast might live?
Maybe I'll give it a try when I have some time to kill.
Well, it's my own fault for being hasty. I blew up two 140c boards because of the reversed Q1, Q2, Q5. On one R35 caught fire (exciting!) this was my first clue that something was wrong. The other board didn't catch fire but was putting out 24v at the output.
I looked over this thread and saw that someone got a message from TubesHunter about the transistors being marked wrong on the boards. Too bad I didn't get that message. But I really should have thoroughly looked through the schematic.
If I replace all the transistors (and R35 of course) do you think the beast might live?
Maybe I'll give it a try when I have some time to kill.
One Board Lives!
One board LIVES!
the ground jumper mentioned earlier connecting the signal ground ("SG") and the "GND" connection near the o/p transistors cured a number of ills on the one board that I didn't blow up.
The DC at the output went down from 24v to 40mv--(much safer I should think) and the trim pot for the quiescent current now works (before no amount of turning could make the reading across R29 deviate from .9mv).
I set the current to 20ma (4.4mv across R29) and hooked up the one channel to a speaker and the thing sounds really good!
Too bad I don't have two channels.
***Just to reiterate what everyone has said-- on the blue boards, Q1, Q2 and Q5 need to be installed reverse of what is marked on the PCB and a jumper wire needs to connected between "SG" and "GND"***
A lot of frustration could be saved if these tips were only included as a xeroxed warning sheet included with the kit. But, then, I really have scoured the schematic before applying voltage.
One board LIVES!
the ground jumper mentioned earlier connecting the signal ground ("SG") and the "GND" connection near the o/p transistors cured a number of ills on the one board that I didn't blow up.
The DC at the output went down from 24v to 40mv--(much safer I should think) and the trim pot for the quiescent current now works (before no amount of turning could make the reading across R29 deviate from .9mv).
I set the current to 20ma (4.4mv across R29) and hooked up the one channel to a speaker and the thing sounds really good!
Too bad I don't have two channels.
***Just to reiterate what everyone has said-- on the blue boards, Q1, Q2 and Q5 need to be installed reverse of what is marked on the PCB and a jumper wire needs to connected between "SG" and "GND"***
A lot of frustration could be saved if these tips were only included as a xeroxed warning sheet included with the kit. But, then, I really have scoured the schematic before applying voltage.
HI
I agree with you it sound dam good .The truth is I already upgraded the first amp but just the transistors and for the input I use BG capacitor .
I decided to build one more amp with further upgrade, resistors like Kaddock MK132 , for capacitors all Black Gate , MJL power transistors and MJE driver transistors .
I built several amp about 20 or more but these amp one of the best sounding amp I ever built .
So I thought I do upgrade as much as possible and I will stick with these amp .
Regards
I agree with you it sound dam good .The truth is I already upgraded the first amp but just the transistors and for the input I use BG capacitor .
I decided to build one more amp with further upgrade, resistors like Kaddock MK132 , for capacitors all Black Gate , MJL power transistors and MJE driver transistors .
I built several amp about 20 or more but these amp one of the best sounding amp I ever built .
So I thought I do upgrade as much as possible and I will stick with these amp .
Regards
Hi.
Ive never built an amp before but Im very interested in these 140 clones. I noticed of Pinkfish there were problems getting them to work. Does anyone know if the current 'improved' kits on ebay are OK?
So all I need is a Tx and some heatsink, chassis etc?
Is it a simple build that I can assemble and use?
Thanks in advance.
Mike
Ive never built an amp before but Im very interested in these 140 clones. I noticed of Pinkfish there were problems getting them to work. Does anyone know if the current 'improved' kits on ebay are OK?
So all I need is a Tx and some heatsink, chassis etc?
Is it a simple build that I can assemble and use?
Thanks in advance.
Mike
Hi Mike,
I finished assembling one of these boards today. Assembly was no problem (noting the orientation of Q5). I checked the components before fitting and matched the transistors for gain as closely as I could with the parts in the kit. I plan to test it in the week and then I'll assemble the other board with different components and compare.
Cheers,
Jon
I finished assembling one of these boards today. Assembly was no problem (noting the orientation of Q5). I checked the components before fitting and matched the transistors for gain as closely as I could with the parts in the kit. I plan to test it in the week and then I'll assemble the other board with different components and compare.
Cheers,
Jon
HI
You can build that amp with some help, it is very simple .
I already built the blue board or the improved kit .
Read the forum , you can find all the info you need but the guy is very helpful to .
A very good amp ! Actually I purchased the second kit and I'm planing to do further improvement's using better parts , higher quality resistors , capacitors etc .
Regards
You can build that amp with some help, it is very simple .
I already built the blue board or the improved kit .
Read the forum , you can find all the info you need but the guy is very helpful to .
A very good amp ! Actually I purchased the second kit and I'm planing to do further improvement's using better parts , higher quality resistors , capacitors etc .
Regards