I'm not sure you can. It would make sense to purchase from a reliable source such as Blues. He and others can be found on this forum, and is base in the US I believe
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I bought mine from Blues. Great matching.
http://www.diyaudio.com/forums/swap-meet/161366-matched-toshiba-fets-sale-33.html
From ebay: probably real but who knows. And how well are they matched ?
http://www.diyaudio.com/forums/swap-meet/161366-matched-toshiba-fets-sale-33.html
From ebay: probably real but who knows. And how well are they matched ?
I bought these: 4 X MATCHED 2SK170 2SK170BL 2SJ74 2SJ74BL FET! - eBay (item 350330237411 end time Dec-13-10 17:15:16 PST)
and then I had a friend with more el.knowhow help me check them. They were macthed very good in pairs, but for the F5 pair (k170-j74) the match was a not so good.
Great news about the new F5 boards. I have a question about the links on this post. When I try to follow them, I end up at a Polish website, I am unable to navigate that site because of language problems. Any place else I could see these photos? Your layouts are so clean that pictures really tell the story. thanks.
My F5 clone effort
Hi,
I have posted completed pictures of my F5 clone here:
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier-44.html#post2378878
your comments are most appreciated.
Cheers.
Hi,
I have posted completed pictures of my F5 clone here:
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier-44.html#post2378878
your comments are most appreciated.
Cheers.
Is there any advantage to use non inductive resistors for the 10 ohm ? I see that in the tubes amp is always good not to have an inductive element in the cathodes, I don't know much of Jfet, but this looks similar.
Thanks,
Davide
Thanks,
Davide
As someone suggested me to use R-core transformers, and living in Japan, I asked Kitamura-kiden a quote for 320 VA R-core transformers. they asked 185 $ per unit. But what are the advantages compared to toroidal transformers ?
At the end for me is going to cost the same either to ship toroid from Canada or to have R-core locally.
Thanks,
Davide
At the end for me is going to cost the same either to ship toroid from Canada or to have R-core locally.
Thanks,
Davide
R-core has separate primaries and secondaries on separate bobbins wide apart, and thus very little inter-winding capacitance.
http://www.diyaudio.com/forums/powe...formers-poor-choice-amp-psus.html#post1929906
Otherwise they are very similar to toroids.
Patrick
http://www.diyaudio.com/forums/powe...formers-poor-choice-amp-psus.html#post1929906
Otherwise they are very similar to toroids.
Patrick
I read (from a few reliable sources) that at least some manufacturers split the primaries and the secondaries so that each bobbin has half of all the windings. Symmetrical wound.
This virtually demands a screen to minimise the primary to secondary HF transmission via the winding capacitance.
This virtually demands a screen to minimise the primary to secondary HF transmission via the winding capacitance.
In different schematics I found different values for R21 and R22. On one paper I found 10k in another one 22k.
What's the recommended value for these two ?
I am trying R-core. I ordered only one to test it, as locally they ship almost for free.
D.
What's the recommended value for these two ?
I am trying R-core. I ordered only one to test it, as locally they ship almost for free.
D.
Dear Nikon1975,
I am just back from Japan !!! 🙂 I was in/ near Nagoya 😉
Here in France we get the Selectronic R-Core, which are great value for the money / they have an electrostatic shield to connect to ground - Once done, all good for audio 🙂
Best regards,
nAr
I am just back from Japan !!! 🙂 I was in/ near Nagoya 😉
Here in France we get the Selectronic R-Core, which are great value for the money / they have an electrostatic shield to connect to ground - Once done, all good for audio 🙂
Best regards,
nAr
The actual value is 10K. Some have modded to 22K, discussion is in here somewhere! When I was ordering parts kits from Tech-DIY, they included both values.
Russellc
Are you sure?
I have some R-cores from China. The primaries and secondaries are NOT on separate bobbins on this trannies!
Franz
Hi,
I was just looking at the f5 service guide and saw that .0033 mf? capacitor across the ac line power inputs. Is this necessary?
Thanks,
JG
I was just looking at the f5 service guide and saw that .0033 mf? capacitor across the ac line power inputs. Is this necessary?
Thanks,
JG
I would expect its like UI core, each secondary have their own primary
I dont know why they called it R core
But I suppose there's an air gap somewhere ?
I need to build my F5