Curly-F4 New Thread
I started a new thread Curly-F4 http://www.diyaudio.com/forums/pass-labs/250205-curly-f4.html#post3797109 which describes my completed implementation of a folded cascode gain stage for the F4.
I started a new thread Curly-F4 http://www.diyaudio.com/forums/pass-labs/250205-curly-f4.html#post3797109 which describes my completed implementation of a folded cascode gain stage for the F4.
Hello.
I´m building a crippled F4 with BA3 as frontend, and have some questions:
1: Can the output capacitor on BA3 be removed, as it seems like C1-C2 on the F4 effectively blocks DC?
2: Are there any reason to retain C3-C4 and R24-R25 when jfets are removed?
Seeing that similar questions are brought up earlier in this thread, but no one came with a concrete answer.
Regards
I´m building a crippled F4 with BA3 as frontend, and have some questions:
1: Can the output capacitor on BA3 be removed, as it seems like C1-C2 on the F4 effectively blocks DC?
2: Are there any reason to retain C3-C4 and R24-R25 when jfets are removed?
Seeing that similar questions are brought up earlier in this thread, but no one came with a concrete answer.
Regards
this one is later/latest F4 iteration ; difference to prior one (R0) is that and clamping diodes
though , both relevant only if you go berserk with input voltage
I built my crippled F4 per post 3354 and 3355 of this thread. I do not use any output cap on BA3B boards nor do I have C3,C4, R24,R25,D3,D4 installed but I defer to ZM if there is now a later reiteration .
Papa's Koan is with early production prototype pcbs equipped ;
I made some changes ( trying to keep it neat ) to pcbs , to make it that last iteration ; I'm sure that I implemented clamping diodes but , beat me , I can't remember did I moved those caps in new position
maybe time to look at those old pics , too lazy to dismantle amp itself
being pretty sane with input level , there is not issue at all , anyway
edit - just checked on pics - I did entire redo to latest R
I made some changes ( trying to keep it neat ) to pcbs , to make it that last iteration ; I'm sure that I implemented clamping diodes but , beat me , I can't remember did I moved those caps in new position
maybe time to look at those old pics , too lazy to dismantle amp itself
being pretty sane with input level , there is not issue at all , anyway
edit - just checked on pics - I did entire redo to latest R
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El cheapo Tube amp to F4 RCA adapters!
Not that it would matter to most here, but as someone who uses an 845 amp driving the DIY F4, I had to find a way to get the line level signal to from the speaker outputs of the 845 to the RCA inputs of the F4. In addition, I have been trying several different resistor options to load the tube amp (per Mr. Pass' suggestions in past articles).
I first cut the ends off a cheap old RCA IC and connected both it and the resistor to the tube amp speaker posts. Works. But over time, I thought to myself that I was not able to use my higher quality ICs, or to change ICs to see if there was a sound difference. So yesterday, I went by Rat Shack and purchased a couple sets of their "gold" plated RCA panel jacks. I soldered some short pieces of wire to them, added the resistor value I wanted to try, and taped them up. I connected them to the tube amp and now I can change RCA ICs in seconds as I desire. The best thing of all, it made a significant change in the sound for the better!
Not that it would matter to most here, but as someone who uses an 845 amp driving the DIY F4, I had to find a way to get the line level signal to from the speaker outputs of the 845 to the RCA inputs of the F4. In addition, I have been trying several different resistor options to load the tube amp (per Mr. Pass' suggestions in past articles).
I first cut the ends off a cheap old RCA IC and connected both it and the resistor to the tube amp speaker posts. Works. But over time, I thought to myself that I was not able to use my higher quality ICs, or to change ICs to see if there was a sound difference. So yesterday, I went by Rat Shack and purchased a couple sets of their "gold" plated RCA panel jacks. I soldered some short pieces of wire to them, added the resistor value I wanted to try, and taped them up. I connected them to the tube amp and now I can change RCA ICs in seconds as I desire. The best thing of all, it made a significant change in the sound for the better!
Zen Mod - would that be WIMA's?
Anyone tried the Cerafines in FirstWatt amps? I built the Shingaclone a while ago and tested many caps. For that cap 906 (I think it was..) the Cerafine was much more to my liking than Simlic...
Got the F4 working btw. Still burning in - too early to proparly compare to the F6... but of course I have...
It's got it's virtues..
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how about both . or Muse for that mater . Blending of cap sounds . Sweet and salty soup not salty and salty soup ?
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SE CCS
Hi,
have anyone tried biasing output stage with additional SE CCS? It can be simple as one LM317 wired as CCS. I am going to try it with 380 mA (3.3R 2W setting resistor). According to article "Leaving class A" by Nelson Pass, SE CCS should lower distortion and change its harmonic profile a bit.
Hi,
have anyone tried biasing output stage with additional SE CCS? It can be simple as one LM317 wired as CCS. I am going to try it with 380 mA (3.3R 2W setting resistor). According to article "Leaving class A" by Nelson Pass, SE CCS should lower distortion and change its harmonic profile a bit.