diy MC-phonostage - Page 2

Onvinyl · 5th August 2002, 11:50 AM

Hi NickC,
I tried those first in my mc-stage. They work, but lack bass and tightness. That is the experience of hifidaddy as well.

I wouldn't use them. This phonoamp is supposed to be a quite good one, really high grade.
My current design does not sound bad, though it is not a killer by now.
There are suggestions to try 2SK240 double-fet instead.
Rudiger

NickC · 6th August 2002, 06:41 AM

how would you connect the circuit then? new to fets world (bjt user). Also some tips on preventing esd would be good? thanks

peranders · 6th August 2002, 10:44 AM

Quote:

Originally posted by NickC
new to fets world (bjt user). Also some tips on preventing esd would be good? thanks

Every semiconductor are sensitive but some are more....

JFET's and BJT will normally not create much trouble but MOSFET's can be sensitive especially those with no gate protection what so ever. Small signal MOSFET's like BS170 are not protected. Also power fet's. Exception from that are Hitachis lateral types 2SJ50, 2SK135 and newer models. If you aren't sure, consult the datasheets.

NickC · 9th August 2002, 03:45 AM

anybody knows where to get the jfets 2sk170 GR model? and how to matched them.(circuit design would be great)

Jocko Homo · 9th August 2002, 05:47 AM

Yes, but only if you want blues. 2SK147s, blue and probably violet.

Jocko

dice45 · 9th August 2002, 08:42 AM

Rüdiger,

best hint for ceramic soldering strips i can give you: lay your hand on an old (non-functional) Tektronix oscilloscope and carefully dismantle, slaughter, butcher it. It is full of those strips.
Circuits: best avoid the side cutter at all and do it with your soldering iron.
Before i forget it: do it with respect and let the mastership of the Tek people how to do proper p2p wiring slowly soak in. Zen style

Use silver solder, it is needed for those Tek cermic soldering strips.

NickC · 3rd September 2002, 04:27 AM

is it possible to use more jfets at the begining of the circuit. it reduces more noise than using one jfet rite. but with have to add resistance to the source for equally distribution of load rite?
what value should it be? and at the output stage should more jfets be used (increase gain) similar to pass pearl. what are the benefits of my suggestion and disadvantages too

Morello · 1st October 2002, 09:19 PM

I suggest that You implement a RF-filter at the input.
2k ohms in series and 100pF shunt to ground.

I have designed a RIAA-stage comprising one 2SK170 and one OPA2134 per channel. It works excellent with extremely low noisefloor.

Best regards\Morello

Werner · 21st October 2002, 10:23 AM

Does anyone have a 2sk240 datasheet? Seems to be a bit hard to find on the net.

Thanks,

W

jcarr · 21st October 2002, 11:21 AM

Werner: I am pretty certain that the 2SK240 has been out of production for some years now, and this is likely why you cannot find a datasheet. From memory, this was a 40V medium-gm low-noise N device. The complementary was called the 2SJ75, I think.

Although I don't think I have a full data sheet, I probably have at least some basic numbers, so if you cannot find anything else, I'll go through my parts catalogs.

regards, jonathan carr

5th August 2002, 11:50 AM	#11
Onvinyl diyAudio Member Join Date: Aug 2002 Location: Germany	try no 2SK369 Hi NickC, I tried those first in my mc-stage. They work, but lack bass and tightness. That is the experience of hifidaddy as well. I wouldn't use them. This phonoamp is supposed to be a quite good one, really high grade. My current design does not sound bad, though it is not a killer by now. There are suggestions to try 2SK240 double-fet instead. Rudiger

9th August 2002, 08:42 AM	#16
dice45 diyAudio Member Join Date: Jan 2002 Location: Munich, Bavaria	Rüdiger, best hint for ceramic soldering strips i can give you: lay your hand on an old (non-functional) Tektronix oscilloscope and carefully dismantle, slaughter, butcher it. It is full of those strips. Circuits: best avoid the side cutter at all and do it with your soldering iron. Before i forget it: do it with respect and let the mastership of the Tek people how to do proper p2p wiring slowly soak in. Zen style Use silver solder, it is needed for those Tek cermic soldering strips. __________________ Greets, Bernhard

1st October 2002, 09:19 PM	#18
Morello diyAudio Member Join Date: Jan 2002 Location: Sweden	I suggest that You implement a RF-filter at the input. 2k ohms in series and 100pF shunt to ground. I have designed a RIAA-stage comprising one 2SK170 and one OPA2134 per channel. It works excellent with extremely low noisefloor. Best regards\Morello __________________ "It was never supposed to be a hit, it was supposed to be a Joe Morello drum solo"- Paul Desmond

21st October 2002, 10:23 AM	#19
Werner diyAudio Member Join Date: Jan 2002 Location: Belgium	2sk240 datasheet Does anyone have a 2sk240 datasheet? Seems to be a bit hard to find on the net. Thanks, W

21st October 2002, 11:21 AM	#20
jcarr diyAudio Member Join Date: Jul 2002 Location: Tokyo, Japan	Werner: I am pretty certain that the 2SK240 has been out of production for some years now, and this is likely why you cannot find a datasheet. From memory, this was a 40V medium-gm low-noise N device. The complementary was called the 2SJ75, I think. Although I don't think I have a full data sheet, I probably have at least some basic numbers, so if you cannot find anything else, I'll go through my parts catalogs. regards, jonathan carr __________________ http://www.lyraconnoisseur.com/, http://www.lyraaudio.com


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6th August 2002, 06:41 AM	#12
NickC diyAudio Member Join Date: Dec 2001 Location: Earth	how would you connect the circuit then? new to fets world (bjt user). Also some tips on preventing esd would be good? thanks

9th August 2002, 03:45 AM	#14
NickC diyAudio Member Join Date: Dec 2001 Location: Earth	anybody knows where to get the jfets 2sk170 GR model? and how to matched them.(circuit design would be great)

9th August 2002, 05:47 AM	#15
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Yes, but only if you want blues. 2SK147s, blue and probably violet. Jocko

3rd September 2002, 04:27 AM	#17
NickC diyAudio Member Join Date: Dec 2001 Location: Earth	is it possible to use more jfets at the begining of the circuit. it reduces more noise than using one jfet rite. but with have to add resistance to the source for equally distribution of load rite? what value should it be? and at the output stage should more jfets be used (increase gain) similar to pass pearl. what are the benefits of my suggestion and disadvantages too

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