Re: or ...
I got a warm, fuzzy feeling. Thought it was Jessica Alba dreaming of me. (If the rumors are true, she's newly single.) Turns out it was you.
Rats.
I'd rather it was her, actually.
Dingus is a highly technical term used by all the rednecks here 'bouts when they find themselves contemplating anything more complicated than a light bulb.
Actually, some of them use it for blown fuses...right before they use the foil off a piece of chewing gum to replace said fuse.
I've been trapped here too long. I'm starting to use the local lingo. The last thing I want to do is "go native." Not here...please...anywhere but here...
(okay...almost anywhere...)
Grey
RKH said:
I got a warm, fuzzy feeling. Thought it was Jessica Alba dreaming of me. (If the rumors are true, she's newly single.) Turns out it was you.
Rats.
I'd rather it was her, actually.
luvdunhill said:
Dingus is a highly technical term used by all the rednecks here 'bouts when they find themselves contemplating anything more complicated than a light bulb.
Actually, some of them use it for blown fuses...right before they use the foil off a piece of chewing gum to replace said fuse.
I've been trapped here too long. I'm starting to use the local lingo. The last thing I want to do is "go native." Not here...please...anywhere but here...
(okay...almost anywhere...)
Grey
Banned
Joined 2002
Banned
Joined 2002
Variac said:Does that mean you GOT MARRIED!!!!!!! I knew you were talking about doing it!!!! It's Official/ Done?
Congrats!
Oh Jeez, now I'M off topic....
Variac
I could have done the ceremony cheaper- I'm the Captain don't you know!
Next august
i have already asked her An externally hosted image should be here but it was not working when we last tested it.
Did a little bit of searching on the forum regarding that LM134 zener-diode thingy that makes up the middle of the F4 ... I remember I built a current source with one before, and was considering it for an Aleph ...
Posting here, along with some opinions from Pass about the part ...
p.s. My Zen v.4 still runs with a Zetex.
p.s.s. Also got a LM134/TLxx good model running in B2Spice (Berkeley).
Also, any word on the C3/R25 and C4/R24 network? Inquiry posted #946 on this thread
Posting here, along with some opinions from Pass about the part ...
p.s. My Zen v.4 still runs with a Zetex.
p.s.s. Also got a LM134/TLxx good model running in B2Spice (Berkeley).
Also, any word on the C3/R25 and C4/R24 network? Inquiry posted #946 on this thread
Banned
Joined 2002
GRollins said:
wait, hold the BOMs! I just noticed that there is a 0.4% and a 0.5% version. Anyone know which sounds better? The most expensive TO92 one I can find is the Microsemi-IPG TL431BCLP that is a 0.4%, anyone know if this might add a bit of prat compared to the cheaper Zetex ZTL431BCSTZ?
:bs:
I think something got lost in the translation there 
cviller said:
This is the point at which the Aleph-X thread transitioned from technical discussion to space-filling. Ironic, but predictable. People are too lazy to read, so they ask questions that have already been answered, thereby making the thread even longer, which made it even more intimidating for those who didn't want to read all that went before, so they asked the same question, thereby making the thread even longer...
Don't get me wrong, I'm pleased the circuit was received as well as it was, but human nature will eventually reveal itself.
Grey
Thanks, GRollins
Two questions about the F4 ...
(1) what is the C3/R25 and C4/R24 network? At first glance, it looks to be power supply filtering downstream of R5 and R22. However, what is the function of R24 and R25? Altering the values don't seem to change frequency response much, nor the distortion spectra.
(2) is a servo loop (crude attempt attached) desirable? Or is a little bit of offset actually good? How much does the DC offset drift during warmup of a cold amplifier?
I spent some time simulating the F4 and it is pure genius. According to simulation (which isn't perfect, but usually tells the general truth), the distortion spectra is carefully contained in very low harmonics, almost fully concentrated on the even-order harmonics. The distortion-to-power relationship is pretty dramatic (i.e. distortion increases with increasing output voltage). All considered, quite an amazing design.
As soon as I clear some other projects, I'm certainly going to solder a F4 together, without a doubt. (my wife already thinks there are too many amps in the basement, why not add a couple more?)
Image attached: F4 with (crude) DC servo loop
Two questions about the F4 ...
(1) what is the C3/R25 and C4/R24 network? At first glance, it looks to be power supply filtering downstream of R5 and R22. However, what is the function of R24 and R25? Altering the values don't seem to change frequency response much, nor the distortion spectra.
(2) is a servo loop (crude attempt attached) desirable? Or is a little bit of offset actually good? How much does the DC offset drift during warmup of a cold amplifier?
I spent some time simulating the F4 and it is pure genius. According to simulation (which isn't perfect, but usually tells the general truth), the distortion spectra is carefully contained in very low harmonics, almost fully concentrated on the even-order harmonics. The distortion-to-power relationship is pretty dramatic (i.e. distortion increases with increasing output voltage). All considered, quite an amazing design.
As soon as I clear some other projects, I'm certainly going to solder a F4 together, without a doubt. (my wife already thinks there are too many amps in the basement, why not add a couple more?)
Image attached: F4 with (crude) DC servo loop
Attachments
I don't have a schematic handy to answer the question about the caps. I'll try to look at it later.
Why do you feel that a DC servo is necessary? It's a power follower, pure and simple. The main difference between the F4 and other follower designs you may have seen is that the F4 incorporates a driver stage. It's a pretty stable circuit. Adding a servo strikes me as a rather arbitrary addition to the circuit.
Grey
Why do you feel that a DC servo is necessary? It's a power follower, pure and simple. The main difference between the F4 and other follower designs you may have seen is that the F4 incorporates a driver stage. It's a pretty stable circuit. Adding a servo strikes me as a rather arbitrary addition to the circuit.
Grey
DC servo to null the output DC offset due to potentiometer drift, natural changes during the warmup phase, etc. Just a consideration. I'm not familiar enough with solid-state push-pull (all of my prior push-pull projects are tubed) to be comfortable with direct coupled and a little DC offset. Tube gear isn't direct coupled and doesn't have DC offset; it's an unfamiliar byproduct of solid state that a DC servo can correct for. I see many highly-regard push-pull designs (Borbely, D’Agostino, Levinson) use servo loops, although Pass certainly falls into the upper echelon of highly-regarded designers.
