if you intend to use those chokes as part of CLC ........ don't ;
ferrite cored chokes (even if bifilar ones , for two rails connection) aren't intended for heavy DC current use
you need either air-core or heavy iron core ones (be it EI , E or CU type of core)
ferrite cored chokes (even if bifilar ones , for two rails connection) aren't intended for heavy DC current use
you need either air-core or heavy iron core ones (be it EI , E or CU type of core)
Some examples, not exactly pcb material.
https://www.hammfg.com/electronics/transformers/choke/195-196
... but we don´t handle 200A!
Right, impossible to find a appropriate (small, cheap. low R, high inductance) choke for PCB mounting and soldering.
Let´s go with MP930-0R1 on SK104 heatsink...
Right, impossible to find a appropriate (small, cheap. low R, high inductance) choke for PCB mounting and soldering.
Let´s go with MP930-0R1 on SK104 heatsink...
you can DIY them , either air core (Lalena online calculator , go for no less than 2.2mH,no more than 0R33 Rdc ........ or EI core
if you want , I have recipe for killer EI chokes of 8-9mH
if you want , I have recipe for killer EI chokes of 8-9mH
Put 2 Amplifer Boards, 2 Supplies Board and 2 Toroid into an 5U Châssis, voila!!!
150VA TTSAS0150 from Toroidy for 2x 75,13€
Batch of 50 237x80mm white soldermask PCB forfrom multi-cb with one piece for 7,87€
Batch of 100 237x80mm white soldermask PCB forfrom multi-cb with one piece for 5,31€
5U Rack is not cheap!
... will finish the main filter this night...
150VA TTSAS0150 from Toroidy for 2x 75,13€
Batch of 50 237x80mm white soldermask PCB forfrom multi-cb with one piece for 7,87€
Batch of 100 237x80mm white soldermask PCB forfrom multi-cb with one piece for 5,31€
5U Rack is not cheap!
... will finish the main filter this night...
Attachments
" I want to post to the community 4 questions for my F6 build *
Share you reasons for the answer please
1) What is the preferred method for a soft start
A timed relay/resistor soft start module or a pair of CL60's in the primaries.
2) I want to have two preamps connected to the amp at the same time.
One Tube and one Solid State
Is it advisable to add the second set of RCAs switched with a toggle
3) Is having 2 toroidal transformers better than one and why.
4) I saw somewhere someone saying they destroyed their f5 by using a
valve preamp.
Is this an issue ?
Or can anyone explain what might have happened.
FR
Share you reasons for the answer please
1) What is the preferred method for a soft start
A timed relay/resistor soft start module or a pair of CL60's in the primaries.
2) I want to have two preamps connected to the amp at the same time.
One Tube and one Solid State
Is it advisable to add the second set of RCAs switched with a toggle
3) Is having 2 toroidal transformers better than one and why.
4) I saw somewhere someone saying they destroyed their f5 by using a
valve preamp.
Is this an issue ?
Or can anyone explain what might have happened.
FR
3) I've heard having two separate capacitor supplies off the one transformer gets you very close to separate transformers.
Basically separate power supplies give you better channel separarion. Probably makes more of a difference when the current through the supply is not constant.
Basically separate power supplies give you better channel separarion. Probably makes more of a difference when the current through the supply is not constant.
1) i use softstart module, it's nice to hear a 'click' sound
2) why not using a toogle on your preamp? get chassis which can accomodate 2 preamp, put toggle swith on input rca, both preamp stay ON should be fine
3) you can build monoblock someday using 2 chassis, bigger bias, less load on transformer, or build 2 amplifier in 1 chassis monoblock
2) why not using a toogle on your preamp? get chassis which can accomodate 2 preamp, put toggle swith on input rca, both preamp stay ON should be fine
3) you can build monoblock someday using 2 chassis, bigger bias, less load on transformer, or build 2 amplifier in 1 chassis monoblock
1) CL-60
2)That will work. You will have a clear preference for one after a week doing that, so the toggle won't matter in the long run.
3)If you build it as monoblocks, or completely dual-mono, yes. If not, not really.
4) Bad preamp.
2)That will work. You will have a clear preference for one after a week doing that, so the toggle won't matter in the long run.
3)If you build it as monoblocks, or completely dual-mono, yes. If not, not really.
4) Bad preamp.
Nelson Pass does this in his First Watt class A stereo amplifier supplies. See page 15 here.
http://www.firstwatt.com/pdf/art_f6_baf.pdf
Well yesterday I replaced the input transistors in my F6 that were purchased from Spencer @ fetaudio.com with the diy store Linear Systems Jfets and was stunned at the transformation of the amp, better sound staging, nice shimmer on cymbals, I could go on....
The Spencer supplied parts 2sk170 and 2sj74 failed analysis, I have raised the matter with him although he has failed to respond, the matter has now been raised with PayPal seeking refund.
asx
The Spencer supplied parts 2sk170 and 2sj74 failed analysis, I have raised the matter with him although he has failed to respond, the matter has now been raised with PayPal seeking refund.
asx
That's weird, I wouldn't say that until I put some proof on the table...
Spencer has always sold real JFET's to a lot of members of this community.
All the ones I got from Spencer were real!
Spencer has always sold real JFET's to a lot of members of this community.
All the ones I got from Spencer were real!
Wholeheartedly agree. I've never had anything but the genuine article from Spencer.
What caused you to replace them in the first place? What is meant by "failed analysis"....and lastly and related to first inquiry, What prompted this analysis? I did notice in your past posts something about a "WTF moment" during bias, and some resistor changes.
Thanks, just trying to understand.
Russellc
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Just a side note - 2SK170 and 2SJ74 Idss is substantially different when running cold and running hot. All the curve traced or measuring them for 1 second pairing is basically invalid when running them in an amplifier with ambient temperature maybe even 30C and the transistor itself at 40C. I had 2 pairs of curve traced matched sets that were matched to 0.14% and 0.85% (per pair, 0.01mA and 0.07mA match in pair, matched by a reputable seller with the curves provided) that when used in +-12V supply as an input buffer (like in F5, F6 etc) went to 8.63% and 8.12% (difference of 0.69mA and 0.72mA in pair)! So basically the curve matched sets were unmatched when used in real world.
I managed to source some K170 and pair the J74 up again, but this time using a simple 12V battery and letting the transistors warm for at least 5 minutes before even measuring the Idss with a multimeter. After doing this the offset of the K170/J74 buffer went from 15mV to basically 0.
I managed to source some K170 and pair the J74 up again, but this time using a simple 12V battery and letting the transistors warm for at least 5 minutes before even measuring the Idss with a multimeter. After doing this the offset of the K170/J74 buffer went from 15mV to basically 0.
But still the transconductance of the j74 is higher than that of the same Idss K170....
This is what Nelson says: http://www.diyaudio.com/forums/pass-labs/258613-diyaudio-firstwatt-f6-111.html#post4423171
🙂
This is what Nelson says: http://www.diyaudio.com/forums/pass-labs/258613-diyaudio-firstwatt-f6-111.html#post4423171
🙂