TYVM Zen. So replacing Cs 1 and 2 is not a good idea. So then I'd add the new hi-pass coupling cap before the input-load resistor and use 47K as the load value? If so, even this idiot can do that.
But Cs 1 and 2 definitely are carrying the signal; yes? If so, it makes sense to use the highest-quality caps there that we choose to afford. How about for Cs 3 and 4?
C1 & C2 are more DC level shifters , than signal carrying caps ; for better sleep , you can bypass them with something as 10nF MKC (polycarbonats) ; ;that's , at least , my fave type for bypass
C3 and C4 are there in bias circ and no need for them to be of any better quality than proper industrial type
C3 and C4 are there in bias circ and no need for them to be of any better quality than proper industrial type
Yes, they are.
In simplified form, without going any deeper (ignoring TL431 dynamic impedance, Cgs of output stage transistors and all that sort of stuff) the formula is as follows:
f=1/2pi (R6 II R7) (C1+C2)
Yes, but you will get 6dB/oct slope only.
(I've done it in the past to similar output topologies, btw)
If your filter frequency isn't critical to the 10th of an octave, just use the formula above and be done with it.
@Zen Mod - C3 and C4 serve several purposes, but they are in the signal path. Do the AC signal path analysis.
elektroj, TYVM. The formula I've been using for decades for RC filters is F = 159155/RC where F = Filter Point in Hertz, R = resistance in Ohms, and C = capacitance in microFarads. I have no idea how to read your formula. Is the equivalent simply that C currently = 220uF and R = 10K-Ohms? That makes the FP 0.07Hz. So for a 72Hz filter, I'd use 0.22uF caps?
NP answered my e-mail last nite: "I would leave those caps as they are because they are used as part of the supply system for the Jfets.
Presuming that this is the stock F4, the input impedance is 47.5K ohm, and you can place a capacitor in series with the input using that value for a filter."
I don't like the idea of 'lytic caps in series with the signal, but what the hell do I know about it? (The answer is 'virtually nothing'.)
So...replace Cs 1 and 2 with much-smaller, highest-quality caps, or add a cap at the input and improve the quality of Cs 1 and 2*?
And it's more complicated than the above. I'll be using 2 amps and biamping vertically. In the low-frequency channel--that is the one with the hi-pass filtering and feeding the upper-bass/lower-MR driver and the internal bass amp--probably I'd simply add a cap at the frontend. The speaker rolls off this signal starting at 500Hz (1st-order). The upper-frequency channel would get no additional filtering but would get improved Cs 1 and 2. At least that's the 'plan' before I've even had my hands on one amp.
* as in replace them with BlackGates.
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jeffreybehr, I presented the formula in its classic form:
f=1/2pi x R x C
where C is expressed in Farads and R in Ohms.
If you do the math, you will arrive at the same simplified formula you've been using for Ohms and microFarads.
Your values are correct. 0.22uF will give 72Hz
=========
EDIT- Oops, I was referring to F4 schematic dated 11/8/06! Now I see that actual F4 schematic r0 6/4/07 look different
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jeffreybehr, I am sorry, it will be, indeed, difficult to define -3dB point with C1 and C2 since they're no longer working into fixed 10k load as in older schematic. It looks that you should stick to filter at the input.
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OK; hi-pass filter at the input it'll be. 0.056uF will give me 60Hz, right in the lower part of the range.
TYVM all.
I'm wondering if I don't want something very similar to the B5.
Take the output from Impasse preamp and split it, first goes to (a new amp?) that powers the corner horns full range, and the second goes to the F4 which power the subs and has a passive crossover...
I keep starting at the manual for the F4 and there are a lot of possibilities...
Take the output from Impasse preamp and split it, first goes to (a new amp?) that powers the corner horns full range, and the second goes to the F4 which power the subs and has a passive crossover...
I keep starting at the manual for the F4 and there are a lot of possibilities...
I'm looking for a bit of help here regarding the sound quality of the F4. As far as I understand the F4 is very transparent and one is listening more to the signature of the source and the preamp than the signature of the F4. Correct?
I consider to rebuild my (sons) F5 as I'm not very impressed by its performance. It's lacking detail, ambience, dynamics and coherence compared to my other amps and amps I had in my system lately (e.g. Atma-Sphere MKIII OTL).
It's scares me to read that the F4 sounds similar to a F5. I really hope the F4 is better...
So... Will I get more of almost everything using the F4 instead of a F5?
I have a very good preamp (Vacuumstate RTP3D) which should be able to drive the output FETs directly so I'll also try that if I rebuild the F5 to a F4. I'll no matter what try a variation of the FW J2.
I consider to rebuild my (sons) F5 as I'm not very impressed by its performance. It's lacking detail, ambience, dynamics and coherence compared to my other amps and amps I had in my system lately (e.g. Atma-Sphere MKIII OTL).
It's scares me to read that the F4 sounds similar to a F5. I really hope the F4 is better...
So... Will I get more of almost everything using the F4 instead of a F5?
I have a very good preamp (Vacuumstate RTP3D) which should be able to drive the output FETs directly so I'll also try that if I rebuild the F5 to a F4. I'll no matter what try a variation of the FW J2.
well , even if you're B instead of P , you certainly messed up something with F5
either in construction or mating them with wrong spks
F5 is one fine amp , in every instance you mention it's not .
even if your Etalon ( Atma) is pretty respectable .
I made them all ( Papamps , and few of my own ) and I know their rank , comparing to usual mumbojumbo HiEnd drek
either in construction or mating them with wrong spks
F5 is one fine amp , in every instance you mention it's not .
even if your Etalon ( Atma) is pretty respectable .
I made them all ( Papamps , and few of my own ) and I know their rank , comparing to usual mumbojumbo HiEnd drek
F5 is fine amp, but not for everyone. I was impressed in everyway with my version, but still like the BA/F4 better. Some folks are a bit over descriptive in their dislike, forgetting that any of these trumps much more expensive ready built options, at least the ones i have heard. Speaker point is probably as important as anything, some being like American cars,being full of sound and furry, signifying nothing.
Hi Zen Mod
The F5 is built correctly and measuremts confirms this. My speakers are the DTQWT MKII (95dB and the impedance is not under 6 Ohm).
On a regular basis I use about 1 Watt of power and around 4 Watt playing loud.
I have rechecked the F5 several times since the very first day. The bias is very very stable and FFT looks similar to what I have seen online. I do not dislike the F5, it is the best solid state amp I've heard in my system but as I wrote I find the F5 to be lacking details and more compared to other amps I've heard in my system. The Atma-sphere OTL is way more dynamic than the F5 In my system. Soundstage, room information and ambience is WAY better on the OTL than the F5. My own PP 6CA7 amp is also better than the F5 in every way. I'm not a tubeaholic for life, I'm just after the best amp for me. Have you heard any of the Atma-Sphere OTLs in your personal system? They are indeed something very special.
What's your experience with the F4? Is it more transparent than the F5 or should I go after the J2 or maybe the mighty Babelfish J2?!
Or maybe a SIT Circlotron? ;-)
well - it seems that we both forgot some things in our posts - you some more clarity and I few smilies 
F5 is ( paired with adequate spks ) probably one of best amps , for SS crowd .
personally - I don't like F5 that much , being spoiled with da toobz for greater part of my fun with audio .
F4 is - say - more lifelike than F5 , considering that it's adding so little of own character , leaving preamp to dominate .
"lifelike" is sole term which I can find for asked differentiation , without going in Audiophool vocabulary ( and , believe me , I was good in that , in dark ages of my messing with FiFi
)
if you have Allen's pre , you're good ...... just make crippled F4 (balanced or not - your call ) connecting pre with amps through some decent cable ( meaning - decent , not expensive )
my exquisite friend AR2 , who made one of rare Babelfish J2s ( in precious Papa's test bed amp case ) is saying that BJ2 is The Amp .
at least for his spks and his taste .
regarding Atma - I have some experience in making C-trone in my younger and more enthusiastic days ; what I made then (mostly acting smart-a$$ combining crumbs from everywhere ) was one of best amps I ever heard ........ but I didn't had ( in that time )neither gold coins , nor knowledge to keep them going further .
now I know that they were not so different from Atma , but I'm not more interested in any sort of struggle or inconvenience in making and using audio gadgets...... and we must confess that any multimulti-tube amp is PITA
btw - J2 vs. BJ2 - they're not so different ...... any difference is strictly intentional - it's not fun making things exactly as Papa does
F5 is ( paired with adequate spks ) probably one of best amps , for SS crowd .
personally - I don't like F5 that much , being spoiled with da toobz for greater part of my fun with audio .
F4 is - say - more lifelike than F5 , considering that it's adding so little of own character , leaving preamp to dominate .
"lifelike" is sole term which I can find for asked differentiation , without going in Audiophool vocabulary ( and , believe me , I was good in that , in dark ages of my messing with FiFi
)if you have Allen's pre , you're good ...... just make crippled F4 (balanced or not - your call ) connecting pre with amps through some decent cable ( meaning - decent , not expensive
)my exquisite friend AR2 , who made one of rare Babelfish J2s ( in precious Papa's test bed amp case ) is saying that BJ2 is The Amp .
at least for his spks and his taste .
regarding Atma - I have some experience in making C-trone in my younger and more enthusiastic days ; what I made then (mostly acting smart-a$$ combining crumbs from everywhere ) was one of best amps I ever heard ........ but I didn't had ( in that time )neither gold coins , nor knowledge to keep them going further .
now I know that they were not so different from Atma , but I'm not more interested in any sort of struggle or inconvenience in making and using audio gadgets...... and we must confess that any multimulti-tube amp is PITA
btw - J2 vs. BJ2 - they're not so different ...... any difference is strictly intentional - it's not fun making things exactly as Papa does
well - it seems that we both forgot some things in our posts - you some more clarity and I few smilies
Thx, that's what I'm looking for!
I've been on the dark side too, so lifeless and expensive to live there..."lifelike" is sole term which I can find for asked differentiation , without going in Audiophool vocabulary ( and , believe me , I was good in that , in dark ages of my messing with FiFi
I made some decent cables per description of Allen when I were at the dark side...if you have Allen's pre , you're good ...... just make crippled F4 (balanced or not - your call ) connecting pre with amps through some decent cable ( meaning - decent , not expensive
Yes, we must confess... that's why I consider to build a Circlotron using JFETs in the output, toobz on the input and IS-trannie in-between.... Might be The Amp...regarding Atma - I have some experience in making C-trone in my younger and more enthusiastic days ; what I made then (mostly acting smart-a$$ combining crumbs from everywhere ) was one of best amps I ever heard ........ but I didn't had ( in that time )neither gold coins , nor knowledge to keep them going further .
now I know that they were not so different from Atma , but I'm not more interested in any sort of struggle or inconvenience in making and using audio gadgets...... and we must confess that any multimulti-tube amp is PITA
A good starting point for me is always to build the way Papa designed the amps in the first place and go on from there. So, I better heat my iron and make my J2 variant and then the F4. Thx for you time.btw - J2 vs. BJ2 - they're not so different ...... any difference is strictly intentional - it's not fun making things exactly as Papa does
I would li eto try Bablefish J2, but doont know where to find it. Currently the amp that came th eclosest to tube sound for me wasBA3. Rolling you own harmonics teaches one about how we hear things. Very interesting indeed. Nothin greally gives you the musical bloom you get from tubes, bu tnothin gives youtheccuracy of SS. I am trying hybrid with tube preamp driving ba3
NB:
I have the F4's and while I am careful about quoting Papa Pass, as always seem to get it wrong, I remember him saying that a "follower" output stage such as the F-4 tends to pass through the characteristics of the preamp more than other designs. Now considering that the F-4 has no gainstage, that has to make it even more transparent to the pre.
I've heard Chokies Pumpkin and it sounded great, very great in fact! But it was a short audition.
I've had much more experience with the F-4 hooked to SY's Impasse which is tube based pre with high output. My feeling is that the common dream to mate a tube stage to a solid state output stage, which will give the tube sound and greater output power, seldom works as well as it should. But IMHO, It DOES work with the F-4, I haven't heard the Impasse with other amps than the F-4, but with it, the sound has that directness and pristine clarity that it seems tubes are so good at. The Impasse doesn't have the rich old school tube sound, which I wouldn't want, but does have the qualities I mentioned. The combo sounds exceptional to me, so your tube pre should be fine if it has enough output.
Its certainly worth your time to try it and though I realize your expectations are very high so no guarantees, but you might just be satisfied, Imagine that!
Mark
I have the F4's and while I am careful about quoting Papa Pass, as always seem to get it wrong, I remember him saying that a "follower" output stage such as the F-4 tends to pass through the characteristics of the preamp more than other designs. Now considering that the F-4 has no gainstage, that has to make it even more transparent to the pre.
I've heard Chokies Pumpkin and it sounded great, very great in fact! But it was a short audition.
I've had much more experience with the F-4 hooked to SY's Impasse which is tube based pre with high output. My feeling is that the common dream to mate a tube stage to a solid state output stage, which will give the tube sound and greater output power, seldom works as well as it should. But IMHO, It DOES work with the F-4, I haven't heard the Impasse with other amps than the F-4, but with it, the sound has that directness and pristine clarity that it seems tubes are so good at. The Impasse doesn't have the rich old school tube sound, which I wouldn't want, but does have the qualities I mentioned. The combo sounds exceptional to me, so your tube pre should be fine if it has enough output.
Its certainly worth your time to try it and though I realize your expectations are very high so no guarantees, but you might just be satisfied, Imagine that!
Mark
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Hi Mark,Its certainly worth your time to try it and though I realize your expectations are very high so no guarantees, but you might just be satisfied, Imagine that!
Mark
Thank you for you response. Yes, there're no guarantees... As I have the donor amp for the project the cost will be low for the project so no excuses not to try it out.
I believe the RTP3D will be a very good match for the F4.