I read that to mean you should replace Q3 and Q4 on the broken channel
with a pair of matched LSK170/LSJ74.
Getting a matched pair of LSJ74B doesn't necessarily mean they will match
with your existing LSK170.
with a pair of matched LSK170/LSJ74.
Getting a matched pair of LSJ74B doesn't necessarily mean they will match
with your existing LSK170.
yup , need to replace input JFet pair (LSK170/LSJ74) of that channel
sorry, me being too short
🙂
sorry, me being too short
🙂
Does anyone know what will happen when you accidentally swap LSJ74B and LSK170B? Can this cause a burned FET?
(I am not sure if the FET’s were at the correct location. I may have swapped them during the installation, but I can not check it because the remaining FET at Q3 doesn’t have the code on it anymore because of the heat that was caused by Q4 FET).
(I am not sure if the FET’s were at the correct location. I may have swapped them during the installation, but I can not check it because the remaining FET at Q3 doesn’t have the code on it anymore because of the heat that was caused by Q4 FET).
When looking at diyaudio store I can see the LSK170/LSJ74 being sold as a quad, and the LSK170 or LSJ74 as a pair. There is no option for a matched pair of LSK170/LSJ74.
Is there any reliable source in Europe where I can buy a matched pair of LSK170/LSJ74? (I see many on eBay, but not sure if these are the right ones).
Koos
Is there any reliable source in Europe where I can buy a matched pair of LSK170/LSJ74? (I see many on eBay, but not sure if these are the right ones).
Koos
Yes, that is what I am looking for, but I’ve been reading about fake ones.
Where can I buy a matched pair of LSK170/LSJ74?
Thanks in advance! 🙂
Koos
Where can I buy a matched pair of LSK170/LSJ74?
Thanks in advance! 🙂
Koos
EDIT: I mean 2SK170/2SJ74.
Is there any reliable source in Europe that you know of?
Try a guy on eBay called "alweit" - he's not cheap but has well matched, genuine fets - have a few pairs from him over the years.
Not sure if Spencer in HK has any left, but worth a try - and maybe Nicmac (Italy) has some too - see Vendor's Bazaar
Not sure if Spencer in HK has any left, but worth a try - and maybe Nicmac (Italy) has some too - see Vendor's Bazaar
Alweit sells “GR” and “V”, what would be the best choice for the F6?
Thanks in advance.
Koos
I also bought from 'Alweit' e..y-shop AudioFET many times. Very well matched
and genuine TOSHIBA JFets.
I checked today and I saw them only in V-grade and GR-grade. He normally sells them in pairs. Quads on request.
'Punkydawgs`is also a well trusted seller. And a few members here in the diyAudio - forum.
Or buy the matched Linear Systems Jfets from the diyAudio-shop. They sound great. For me no real difference in sound to the original TOSHIBAs. I used them many times in my builds.
Be aware of sellers on the platform e... from Ch...! Most are fakes. Want to make fast money with sh..!
Greets
Dirk 😀
and genuine TOSHIBA JFets.
I checked today and I saw them only in V-grade and GR-grade. He normally sells them in pairs. Quads on request.
'Punkydawgs`is also a well trusted seller. And a few members here in the diyAudio - forum.
Or buy the matched Linear Systems Jfets from the diyAudio-shop. They sound great. For me no real difference in sound to the original TOSHIBAs. I used them many times in my builds.
Be aware of sellers on the platform e... from Ch...! Most are fakes. Want to make fast money with sh..!
Greets
Dirk 😀
I also bought from 'Alweit' e..y-shop AudioFET many times. Very well matched
and genuine TOSHIBA JFets.
I checked today and I saw them only in V-grade and GR-grade. He normally sells them in pairs. Quads on request.
'Punkydawgs`is also a well trusted seller. And a few members here in the diyAudio - forum.
Or buy the matched Linear Systems Jfets from the diyAudio-shop. They sound great. For me no real difference in sound to the original TOSHIBAs. I used them many times in my builds.
Be aware of sellers on the platform e... from Ch...! Most are fakes. Want to make fast money with sh..!
Greets
Dirk 😀
Thanks for the advise Dirk!
Which would you choose for the F6, “GR” or “V” ?
(For the other channel I used the Lineair System FET’s from the diyaudio store, but since I only need for one channel now I am looking into buying from Alweit).
to AcousticEmotion
I would send 'Alweit' an email and ask him if he has some V-grade in the very low mA-range.
BL-grade (Idss 6 - 12 mA)
V- grade (Idss 10 - 20 mA)
The JFets which are used are most often at around 8 - 10mA.
I think a v-grade pair in the very low range (10 - 11mA) should work.
But you will have a small difference from one channel to the other (left-right).
I hope it will not be audible.
Greets
Dirk
I would send 'Alweit' an email and ask him if he has some V-grade in the very low mA-range.
BL-grade (Idss 6 - 12 mA)
V- grade (Idss 10 - 20 mA)
The JFets which are used are most often at around 8 - 10mA.
I think a v-grade pair in the very low range (10 - 11mA) should work.
But you will have a small difference from one channel to the other (left-right).
I hope it will not be audible.
Greets
Dirk
But I also agree with 2 picoDumbs.
I would change all 4 JFets and would try to find them in the correct Idss-range.
I know - expensive experience.
Greets
Dirk
I would change all 4 JFets and would try to find them in the correct Idss-range.
I know - expensive experience.
Greets
Dirk
to AcousticEmotion
I copy from the speech of Mr. Pass about the F6-amp (Burning Amp Festival 2012):
In this circuit, the input Jfets were chosen for Idss at 8 mA or so, but you can get them with Idss up to 20 mA, which times the 23 volt supply will exceed their 0.4 watt rating. Or you might try some other Jfets with higher Idss or higher supply voltages. If you find that you need to degenerate the input Jfets with some resistance, you will find that there is little or noperformance penalty for small resistance values.
You can read the complete text on the FirstWatt-site. Articles - 2012 - F6 Talk at Burning
Amp festival 2012
Greets
Dirk
I copy from the speech of Mr. Pass about the F6-amp (Burning Amp Festival 2012):
In this circuit, the input Jfets were chosen for Idss at 8 mA or so, but you can get them with Idss up to 20 mA, which times the 23 volt supply will exceed their 0.4 watt rating. Or you might try some other Jfets with higher Idss or higher supply voltages. If you find that you need to degenerate the input Jfets with some resistance, you will find that there is little or noperformance penalty for small resistance values.
You can read the complete text on the FirstWatt-site. Articles - 2012 - F6 Talk at Burning
Amp festival 2012
Greets
Dirk
Another recommend for "alweit" Iv'e had both jfets/MOSfet from the DIY store and alweit over the years and I can't hear/tell any sonic differences between either. My issue (as many in UK/Europe) are the duties and shipping, making the DIYstore items + 50% purchase price and a wait of 4 weeks + for delivery from the USA. Alweit (being based in Israel) shipping is much less and only 7 days for delivery, usually.
Last edited: