Nobody really needs more than one, unless you active crossover...
But that doesn't stop us.
My queue is currently 4 amps deep;
F5T v2 for the official build guide
F4, also for the build guide
Aleph J, on new PCB, (currently in limbo, but should get going soon enough)
F6 with Cinemags and R100, as I have a set of R100...
Yes. I am crazy.
Ain't DIY grand?
@ Antoinel -as I said - long rope
nothing fancy - due to nice tempco of Sony Vfets - it will be something simple as just two additional rails up and down , simple shunt regged to some ++ and -- 25Vdc , then resistive dividers to gates
edit - due to recent xperience with venerable Sony TA-5650 , I despise voltage multipliers even more .......
so additional rail will be based on proper separate windings , or separate small xformer
nothing fancy - due to nice tempco of Sony Vfets - it will be something simple as just two additional rails up and down , simple shunt regged to some ++ and -- 25Vdc , then resistive dividers to gates
edit - due to recent xperience with venerable Sony TA-5650 , I despise voltage multipliers even more .......
so additional rail will be based on proper separate windings , or separate small xformer
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It all becomes very subtle work of intuition, mixed mildly with science.
One has to let go of assumptions and listen deeply, yet try to be scientific enough to look at the data, and repeat actual tests.
I agree with your Onetics evaluation totally. By default I think it's the most honest one of the group regardless. But this will not appeal to everyone!
The scope measurements of all three look real close. So it's the JFETs making the major differences I guess. But you can clearly hear differences in all types I have tried - Onetics, Jensen and Cinemag.
Zen Mod: It is time to ask Mr. Pass to release a teaser on F7. F6 has been well characterized and thoroughly undestood. A gold mine which has been almost exhausted. What next to re-ignite a buzz like that experienced with F6?ZM has been nagging me for information on the F6. I have a very nice
sounding prototype, but the design and the article that accompanies it
have some details remaining.
However, I can afford to put out this teaser:
In al honesty, let's get a few more F6 'back from the wild' so to speak, and make sure that the first production PCB (tea-bag's) is rock solid. There a ton of variables in this amp... Let's make them and document it.
And also, let's not forget that the F5Turbo is just now starting to make it into the hands of the end-users and that design could use a bit of learning and 'production savvy'
And... The AB100 was just released, and it's going to need a bit of community support to update it to commonly available parts, and make a PCB, etc...
As much as I would love to see the F7, and believe me, I would love to, there is plenty of Pass design that could use community support.
...I'm just sayin'...
And also, let's not forget that the F5Turbo is just now starting to make it into the hands of the end-users and that design could use a bit of learning and 'production savvy'
And... The AB100 was just released, and it's going to need a bit of community support to update it to commonly available parts, and make a PCB, etc...
As much as I would love to see the F7, and believe me, I would love to, there is plenty of Pass design that could use community support.
...I'm just sayin'...
Thank you for your post. Please clarify AB100.In al honesty, let's get a few more F6 'back from the wild' so to speak, and make sure that the first production PCB (tea-bag's) is rock solid. There a ton of variables in this amp... Let's make them and document it.
And also, let's not forget that the F5Turbo is just now starting to make it into the hands of the end-users and that design could use a bit of learning and 'production savvy'
And... The AB100 was just released, and it's going to need a bit of community support to update it to commonly available parts, and make a PCB, etc...
As much as I would love to see the F7, and believe me, I would love to, there is plenty of Pass design that could use community support.
...I'm just sayin'...
In al honesty, let's get a few more F6 'back from the wild' so to speak, and make sure that the first production PCB (tea-bag's) is rock solid. There a ton of variables in this amp... Let's make them and document it.
And also, let's not forget that the F5Turbo is just now starting to make it into the hands of the end-users and that design could use a bit of learning and 'production savvy'
And... The AB100 was just released, and it's going to need a bit of community support to update it to commonly available parts, and make a PCB, etc...
As much as I would love to see the F7, and believe me, I would love to, there is plenty of Pass design that could use community support.
...I'm just sayin'...
I'm with 6L6 on this - there are a ton of variables with the F6 - I feel just because I have it running that doesn't mean I have something yet to discover. Being able to look at distortion spectra is only a set of probes away and they are in the mail (literally)
Also Zm has teased us with his VFet comments
"I'm thinkin' of F6 lookalike with 2SK60 and 2SJ18 ( so having complementary pair of VFets) , using 600:1200s ( meaning 150+150:300+300) repeater .
logically ,connected as 150:300+300 , having some 3db in xformer phase splitter itself
but , that's on loooong rope , having at least 3 projects tied on same line"
I'm going to see if by looking at Mike R's SIT pieces I can figure out how to incorporate the bias supply based on the 15V transformer and integrate the Sonys in the F6 circuit. Never have done this but it would be worth the learning curve or
maybe it will move up ZMs line
Best
Bob
Pa sent me F7 Teaser for ya .......
joking , off course
here's quick draw of Sony Vfet complementary F6 concept
time for another public disgrace of Mighty ZM
I'm not going to try it in next ...... 6 months ......... or even later
disclaimer - my main spks are 16 Ohms , so for my needs everything is relaxed , regarding OLG , CLG ,NFB,yukyuk
edit : recommended reading , needed for circuit calc : https://dl.dropbox.com/u/20665608/SONY VFET AES.rar , tnx to RK R
dunno how long it will be there , so down it
editedit : for sorta useful logic for circ calc , see Pa's BA3 article ; scroll down to my comment , where I done all work , decrypting differences between explanation and schm nomenclature
joking , off course
here's quick draw of Sony Vfet complementary F6 concept
time for another public disgrace of Mighty ZM
I'm not going to try it in next ...... 6 months ......... or even later
disclaimer - my main spks are 16 Ohms , so for my needs everything is relaxed , regarding OLG , CLG ,NFB,yukyuk
edit : recommended reading , needed for circuit calc : https://dl.dropbox.com/u/20665608/SONY VFET AES.rar , tnx to RK R
dunno how long it will be there , so down it
editedit : for sorta useful logic for circ calc , see Pa's BA3 article ; scroll down to my comment , where I done all work
, decrypting differences between explanation and schm nomenclatureAttachments
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Thanks Zen Mod for the valuable schematic and info. Best regards.
joking , off course
here's quick draw of Sony Vfet complementary F6 concept
time for another public disgrace of Mighty ZM
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not much for chewing
just look at it in blocks - front same as in F6 , bottom out same , upper out flipped
biasing for bottom - depletion , keeping gate well below source
biasing for top - depletion , keeping gate well above source ( aaargh! I wanna P type toobz !!)
floating bias supply for top , floating bias supply for bottom - each made of 28Vac winding going to Graetz,small cap , then rest - made of small Jfet pushing 10-15mA to TL431 shunt reg , then simple resistive divider for establishing proper bias
luckily - they're saying that Sony VFets are pretty well behaving regarding tempco , so no need for further complication
whatever - as every concept , it needs verification in praxis
just look at it in blocks - front same as in F6 , bottom out same , upper out flipped
biasing for bottom - depletion , keeping gate well below source
biasing for top - depletion , keeping gate well above source ( aaargh! I wanna P type toobz !!)
floating bias supply for top , floating bias supply for bottom - each made of 28Vac winding going to Graetz,small cap , then rest - made of small Jfet pushing 10-15mA to TL431 shunt reg , then simple resistive divider for establishing proper bias
luckily - they're saying that Sony VFets are pretty well behaving regarding tempco , so no need for further complication
whatever - as every concept , it needs verification in praxis
back to normal F6 at the moment....!
I just do my second run with the F6 using Permaneders boards....
At the moment I have heavy k2 about 20 -14 db over k3. I already tried different SS pairs.
At the first tries I got only 0,035% THD/1W/8Ohm, I changed later the upper and lower SS and THD went down to 0,012%, very nice!
But why? I thought the circuit is purely symmetric.... why does the place influence so heavy the THD?
May be the circuit is not 100% symmetric because the pots are separate for bias and offset and not like in F5 both pots care for bias and offset equally.....
Next step I have to look if the persistant k2 dominance is coming from an input J-Fets mismatch......
I just do my second run with the F6 using Permaneders boards....
At the moment I have heavy k2 about 20 -14 db over k3. I already tried different SS pairs.
At the first tries I got only 0,035% THD/1W/8Ohm, I changed later the upper and lower SS and THD went down to 0,012%, very nice!
But why? I thought the circuit is purely symmetric.... why does the place influence so heavy the THD?
May be the circuit is not 100% symmetric because the pots are separate for bias and offset and not like in F5 both pots care for bias and offset equally.....
Next step I have to look if the persistant k2 dominance is coming from an input J-Fets mismatch......
correct , and not correct
facts :
1. xformer windings are quadrifilar ; that means somewhat highish capacitance between them
2.lower secondary is sort of sitting on lower rail potential all the time , while
3. upper secondary is floating with output potential ;
result: that (2 vs. 3) , and fact that upper biasing net is really using it's bootstrap function , is really introducing capacitance issue in game
whatever - as Pa said - that's not an issue if you are aware of it - sonic results of F6 are confirming that
our beta testing guys ( you know who you are ) already gave us primary info about that ; with your chip about flipping places of SS , we know more
edit: it's much easier to be clever (fart) post hoc ; being clever and make a hoc is where men are different from boyz
your truly , Mighty Boy ZM
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THX very much Zen Mod!
And to understand you 10% more i add this.....!
"In the design and analysis of experiments, post-hoc analysis (from Latin post hoc, "after this") consists of looking at the data—after the experiment has concluded—for patterns that were not specified a priori. It is sometimes called by critics data dredging to evoke the sense that the more one looks the more likely something will be found. More subtly, each time a pattern in the data is considered, a statistical test is effectively performed."
BTW why do you want to take a complementary pair of SITs and no two SK82? Many of us may have at home....
And to understand you 10% more i add this.....!
"In the design and analysis of experiments, post-hoc analysis (from Latin post hoc, "after this") consists of looking at the data—after the experiment has concluded—for patterns that were not specified a priori. It is sometimes called by critics data dredging to evoke the sense that the more one looks the more likely something will be found. More subtly, each time a pattern in the data is considered, a statistical test is effectively performed."
BTW why do you want to take a complementary pair of SITs and no two SK82? Many of us may have at home....
because I have ( well , not exactly "I" , but Bata Bane - he acquired them for rejuvenating his Papa's TA-5650) leftovers - 2+2 pairs ;
whatever - it's easy to accommodate biasing scheme for complementary , taking care of Pa's arrangement (upper ref. to gnd) ; I would still go to both biasing circs based on floating supplies , it's easier to grasp
as I said - it's easy to be smart post hoc
whatever - it's easy to accommodate biasing scheme for complementary , taking care of Pa's arrangement (upper ref. to gnd) ; I would still go to both biasing circs based on floating supplies , it's easier to grasp
as I said - it's easy to be smart post hoc