Babowana said:Hi Papa,
I have a question with F4.
As you might have read, my tube pre has the output impedance
of 10K. Meanwhile, I have a tube buffer amp that could be located
between the pre and F4. But, as F4 has the Jfet input buffer, I do
not want to add the external additional buffer if I could increase
the input impedance of F4 somewhat.
Question: Considering the 10K output impedance of the pre, I
would like to increase the 48K input impedance of F4, increasing
the ground reference resistor at the Jfet input side to 200K. Will
this affect the sound quality of F4? If not, until how big could I
increase it without losing the sound quality?
Many thanks,
not Papa , but orphan 😉
just double it and don't worry
Zen Mod said:
Thanks.
I opened an old book last night, and found that the gain of the pre
is normally specified on the assumption of 47K load. Hmmm . . .
Actually, I have no complaint about the sound quality and audible
frequency response band getting from the current set-up. I just
have thought about a bit more gain by increasing the input
impedance of F4 to shift up the gain of the pre a bit higher, of
course, without losing the sound quality.
These days i'm so busy that I have no time even to shake the
thing clean after peeing. Soon after this time, I will try 100K 🙂
Hi,
I just built an unbalanced passive pre that has 6 inputs, 100k 33-step precision attenuator of log curve and one output. I can use this as an efficient part of my audio system, e.g. sources – passive pre – power amp, or sources – passive pre – active pre – power amp. Not only for these, but as you might guess, I could enjoy an advantage with this passive pre. It can be a good tool, providing me with easy testing of my different versions of unbalanced DIY active pres naked with no selector and no volume control . . . Sure, for the best one matching well with F4 . . .
Listening to the group of those days, Led Jeppelin – two CDs of BBC Sessions . . .
I prefer CD Two to CD One . . .
I just built an unbalanced passive pre that has 6 inputs, 100k 33-step precision attenuator of log curve and one output. I can use this as an efficient part of my audio system, e.g. sources – passive pre – power amp, or sources – passive pre – active pre – power amp. Not only for these, but as you might guess, I could enjoy an advantage with this passive pre. It can be a good tool, providing me with easy testing of my different versions of unbalanced DIY active pres naked with no selector and no volume control . . . Sure, for the best one matching well with F4 . . .
Listening to the group of those days, Led Jeppelin – two CDs of BBC Sessions . . .
I prefer CD Two to CD One . . .
Attachments
Babowana said:
J . . . ? Gee . . . Z . . . !
Often, too often, the connection between the brain picture and
the mouth is misaligned. It seems to be my chronic disease . . .
I might need a better quality interconnector . . .
Babowana said:To whom had interest in my Babo Zen:
Do you remember?
The reason why I gave the name as "Babo (Dumb)"?
The reason was that I used strange complement sets of Jfets
and Mosfets. I used a strange combo of J310 (U5) and 2SJ108GR
(U6) and an odd combo of IRFP250N (Q1) and IRFP240 (Q2) of IR.
Nevertheless, the sound was very good.
By the way, recently I built the “first-watt” F4 using 2SK170BL,
2SJ74V, IRFP240 (Samsung) and IRFP9240 (Fairchild). And,
after this still I had left-over of these FETs. Therefore, I replaced
the old FETs with these new ones. After the renewal, I adjusted
the bias at 1A per channel and the output dc offset to the level
lower than 20mV when the amp was reached to the steady-state
heat balance.
I jumped into my CD player and threw in Taj Mahal, “Ain’t
Gwine Whistle Dixie (Anymo’) (8:37)”.
The sound changed from the 2nd harmonic character slightly to
the 3rd harmonic sound. The sound was improved 😀
I felt like enjoying the whistle, electric strings, drums,
percussions, brasses, and their rich and natural harmonies under
the bright and warm sunshine shining from the blue sky at the sea
side. The sound was really cool. I raised volume up, but the sound
didn’t go hard. It was still easy and cool . . .
I can’t call this “Babo Zen” anymore.
I should call this “Papa’s Zen5 with Input JFETs”. The real name.
(I still love the nick name, Babo Zen, tho . . .)
I’d like recommend you to try to build not only F4, but also Papa’s
Zen5 having the JFET inputs. You can’t regret. I’m 99% sure 😀
BABO ZEN !!! BABO ZEN!!!! BABOZENJY!!
Now it's F4??
With 13 volt rails ???
Wonder what ZV5 would do with 13volts.? Baby BaboZenjy??!!
Got to stop!!!
I’m a poor tailor. Yeah . . . +/-13V.
My rails offer me very clean +/-9V output swing for my sealed 84dB/8ohms miniature speakers. Size of clean power? 9x9/2/8 = 5W. 5W+5W! Aren’t they enough? A bit more than enough for my 160 sq.m apartment size. I’m a small man owning a small apartment. As F4 has good output current capacity, I could have 5W/8ohms, 10W/4ohms and 20W/2ohms . . . linearly . . .
Last night, I was listening to CCR at the end of series of other favourite CDs. Susie Q always reminds me of two things: One famous Korean comedian (passed away) who was playing very funny Susie Q dance, and rabbit girls in Apocalypse, Francis Ford Coppola.
Both . . .
I’m enjoying BaboZen at home in Busan . . .
And, I’m enjoying F4 here . . . 🙂
I would welcome BaboZen of +/-13V rails.
My rails offer me very clean +/-9V output swing for my sealed 84dB/8ohms miniature speakers. Size of clean power? 9x9/2/8 = 5W. 5W+5W! Aren’t they enough? A bit more than enough for my 160 sq.m apartment size. I’m a small man owning a small apartment. As F4 has good output current capacity, I could have 5W/8ohms, 10W/4ohms and 20W/2ohms . . . linearly . . .
Last night, I was listening to CCR at the end of series of other favourite CDs. Susie Q always reminds me of two things: One famous Korean comedian (passed away) who was playing very funny Susie Q dance, and rabbit girls in Apocalypse, Francis Ford Coppola.
Both . . .
I’m enjoying BaboZen at home in Busan . . .
And, I’m enjoying F4 here . . . 🙂
I would welcome BaboZen of +/-13V rails.
jupiterjune said:
If you start digging a hole on the beach at Manasquan and keep going until you see daylight............😉
sandstorm33 said:
If I know where the beach at Manasquan is, I could confirm.
Ahha . . . If I dig opposite direction till I see starlight . . . yeah . . . 😉
Babowana said:
If I know where the beach at Manasquan is, I could confirm.
Ahha . . . If I dig opposite direction till I see starlight . . . yeah . . . 😉
Manasquan is five minutes SOUTH of Sea Girt...........moistened by The Atlantic Ocean. On a very good day you can see Brooklyn.
I wonder what the skeleton of a BABY BABOZENJY looks like(13vlts plus/minus)?????
Where's my shovel???
sandstorm33 said:
No. Not +/-13V rails for BaboZen. I would like to clarify as follows:
- F4 : +/-13V rails
- BaboZen: +/-20V rails.
My BaboZen has 2x20V secondary transformer at total 800VA.
If we want +/-13V rails for BaboZen, we could use 2x17V secondary transformer.
Then, we will get DC of 1.4x17 = 23.8V.
But, there would be voltage loss of about 2.8V thru components.
So, actual DC would be 23.8-2.8 = 21V.
And, we need Vds of 8V across the rail voltage regulator.
Then, the rail voltage would be about 21-8=13V.
And, to get this target rail voltage, the reference zener voltage
of the regulator should be 13+4 = 17V. (Two 9.1V zeners in
series should be ok.)
The final rail voltage, however, might be somewhat different
depending on the bias current. (probably inbetween 13-14V)
Babowana said:
No. Not +/-13V rails for BaboZen. I would like to clarify as follows:
- F4 : +/-13V rails
- BaboZen: +/-20V rails.
My BaboZen has 2x20V secondary transformer at total 800VA.
If we want +/-13V rails for BaboZen, we could use 2x17V secondary transformer.
Then, we will get DC of 1.4x17 = 23.8V.
But, there would be voltage loss of about 2.8V thru components.
So, actual DC would be 23.8-2.8 = 21V.
And, we need Vds of 8V across the rail voltage regulator.
Then, the rail voltage would be about 21-8=13V.
And, to get this target rail voltage, the reference zener voltage
of the regulator should be 13+4 = 17V. (Two 9.1V zeners in
series should be ok.)
The final rail voltage, however, might be somewhat different
depending on the bias current. (probably inbetween 13-14V)
Do we need the regulator??Do we need the mosfet in the PS. How about CRCC.. say 60k uf total each rail.. We wind up with maybe +/-15 volts from 12-0-12 trans (10amps). I've got one of those!!. just seems crazy to lose so much on such low voltage rails.
The 12-0-12 trans is considered too small for BaboZen.
We need to remember that BaboZen has the gain mosfet sources
directly seeing the supply rails. So, we need to have clean rails,
introducing the active voltage regulators.
For your info, I'm using 12-0-12 trans for F4 . . .
We need to remember that BaboZen has the gain mosfet sources
directly seeing the supply rails. So, we need to have clean rails,
introducing the active voltage regulators.
For your info, I'm using 12-0-12 trans for F4 . . .
Well, I tried your suggestion, digging a hole on the beach at Manasquan. A large wave came in, and now I have a surfboard stuck in my ....
Too bad that BaboZen5 needs the monster PS. I have a regular PS laying around all wired up--I had thought briefly that I could use it for Babozen5--then I remembered......
Too bad that BaboZen5 needs the monster PS. I have a regular PS laying around all wired up--I had thought briefly that I could use it for Babozen5--then I remembered......
jupiterjune said:
We have to complain Papa, Nelson . . .
Giving him my eye shot of discontent with the heavy PS, I built it.
And, listening to the music, I could not find any good reason to dismantle it 😉
jupiterjune said:
Never fails.. Drink enough of the California Grape Juice and one hallucinates and conjures the impossible.... Oh well maybe the F4 will save the day or Grey's Mini. I just need ten watts or a little less to fill my cell with music.
As for Babo Zen I'm relieved that it has retained its integrity and has not become a lose pile of parts... and one of these days that bargain transformer will surface ..............
Babowana said:OK, now I completed a new set up for my new living space where
I am free alone.
The power is my F4 of 8W+8W. Do you need any info about F4?
The speakers are again ATC SCM7. I had to buy one more pair as
wife and children forced me to leave the same pair at home.
Wow . . . the F4 delivers big tube sound to the speakers almost
without adding or deleting the tube charactors. Fantastic!
Different taste . . . but I also like my MOSFET pre with F4.
The reason why I am using tube pre here is due to eye attraction . . .
I do not know when I return myself to the MOSFET pre tho . . .
What is the mosfet preamp that you are'nt using??Also seems to me you said you didnt match devices ..... ?? Which devices are unmatched....?? I still want BABOZEN..May have to buy the BIG iron
sandstorm33 said:What is the mosfet preamp that you are'nt using??
Also seems to me you said you didnt match devices ..... ??
Which devices are unmatched....??
My own mosfet design (looks similar as the tube SRPP) . . .
Right. Since I was using sigle pair of gain mosfets, I did not consider any matching absolutely necessary. And, as we have two adjustable resistors, we could easily adjust any of two for bias and another for near-zero offset voltage reasonably frozen. Of course, if our budget says ok, then we could go with all matching mosfets . . .
I used the cheapest 1%-resitors of no name . . .
I used the cheapest 5%-wire-wound-power resisters of no name . . .
I used cheap electro caps of no name . . .
But, I recommend to have nice small film caps in parallel with the big caps arranged to reduce the output impedance of the regulator behind the regulator mosfet Source pin . . .
If you have marginal budget you could donate, pls feel free to go buy audiophile electrolytic caps, etc . . .
Babowana said:
My own mosfet design (looks similar as the tube SRPP) . . .
Right. Since I was using sigle pair of gain mosfets, I did not consider any matching absolutely necessary. And, as we have two adjustable resistors, we could easily adjust any of two for bias and another for near-zero offset voltage reasonably frozen. Of course, if our budget says ok, then we could go with all matching mosfets . . .
I used the cheapest 1%-resitors of no name . . .
I used the cheapest 5%-wire-wound-power resisters of no name . . .
I used cheap electro caps of no name . . .
But, I recommend to have nice small film caps in parallel with the big caps arranged to reduce the output impedance of the regulator behind the regulator mosfet Source pin . . .
If you have marginal budget you could donate, pls feel free to go buy audiophile electrolytic caps, etc . . .
Is this (more or less) what we are talking about???Single pair of Gain mosfets???
Attachments
sandstorm33 said:
Mmm . . . Yes, ‘one’ pair as you are showing.
By the way, you demonstrate the example pair using F4 while we are talking about BaboZen . . . ?
Regarding my F4, even though it has low rail voltages (+/-13V), I use three pairs of the gain mosfets. For these pairs, I did a brief matching test just to see whether any one of them is far away from the generous standard deviation. I’m not a perfectionist . . . I want to let my life stay somewhat easier . . .
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