More on output protection; diff pair
Hello Choky again,
1. Regarding the protection around the output transistor, you appear to have used a different sort of circuit:
The Babbelfish version has the output of the second transistor of the diff pair going direct to the source of the output transistor (Q7);
The original Aleph design has the output of the second transistor of the diff pair going to V-.
Does it matter? Can I leave it the older way? (And for my education, why did you change it?)
2. What function do the 43 ohm resistors at the source of the diff pair serve? Are they optional, or would you strongly suggest I keep them?
This is all lots of fun, I think.
Regards,
George.
Hello Choky again,
1. Regarding the protection around the output transistor, you appear to have used a different sort of circuit:
The Babbelfish version has the output of the second transistor of the diff pair going direct to the source of the output transistor (Q7);
The original Aleph design has the output of the second transistor of the diff pair going to V-.
Does it matter? Can I leave it the older way? (And for my education, why did you change it?)
2. What function do the 43 ohm resistors at the source of the diff pair serve? Are they optional, or would you strongly suggest I keep them?
This is all lots of fun, I think.
Regards,
George.
Re: More on output protection; diff pair
1.second jfet in diff pair is connected in sorta folded cascode ; I tried it and looks that it's little better like that; if not-certainly is funnier 😉
you can connect it in way you wish....."old" way or Chokyfied,whatever 😉
regarding current protection:
if you look at foist page of thread where is my schmtc,look at next parts:
R21 , R20 , R18 , Q5.........simple-current through R21 is transformed in voltage,then divided with R20/R18 and when you have 0,6 V on R18- Q5 start conducting and decreasing voltage (signaL,Averaged DC,whatever....) on gate of Q7............
just study these parts in Aleph 30 and calculate what you exactly want.....
43 ohms in sources of diff pair.....better current sharing,sorta local degeneration,blah blah..........use it if you want,it's not necessary
GeorgeBoles said:
1.second jfet in diff pair is connected in sorta folded cascode ; I tried it and looks that it's little better like that; if not-certainly is funnier 😉
you can connect it in way you wish....."old" way or Chokyfied,whatever 😉
regarding current protection:
if you look at foist page of thread where is my schmtc,look at next parts:
R21 , R20 , R18 , Q5.........simple-current through R21 is transformed in voltage,then divided with R20/R18 and when you have 0,6 V on R18- Q5 start conducting and decreasing voltage (signaL,Averaged DC,whatever....) on gate of Q7............
just study these parts in Aleph 30 and calculate what you exactly want.....
43 ohms in sources of diff pair.....better current sharing,sorta local degeneration,blah blah..........use it if you want,it's not necessary
Re: Re: Re: Aleph 3/Babbelfish conversion
To be completely honest, my preamp is not balanced, but I just wanted the right value for future possibilities. Mark G., who works in the film theatre industry claims in the home environment, balanced is not needed, but still since my BrianGT boards have those provisions, I would like the value there in the future.
Thanks again Choky for your excellent contributions!!! 🙂
Kind regards, Bill
choky said:
try like this
closed S1-unbal input
open S1 - bal input
470K is there just in case-when you forget to connect input cables
To be completely honest, my preamp is not balanced, but I just wanted the right value for future possibilities. Mark G., who works in the film theatre industry claims in the home environment, balanced is not needed, but still since my BrianGT boards have those provisions, I would like the value there in the future.
Thanks again Choky for your excellent contributions!!! 🙂
Kind regards, Bill
Bill, in my experience, going balanced means an end to all interconnect cable differences, whatever the cause, so I think it's well worth it. 😉
pinkmouse said:
My biggest problem, is my CD player/ Musical Fidelity Tri Vista DAC is not balanced. Unless there are other DACs that are balanced that I could build?
Bill
Well, Russ is working on one at the moment.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=79456
Probably best we leave this off topic discussion now though. 😉
http://www.diyaudio.com/forums/showthread.php?s=&threadid=79456
Probably best we leave this off topic discussion now though. 😉
BillWW said:
when source is of really good quality,it is not worth huge efforts (to make,steal,starve for etc) converting to balanced
if transition to balanced is easy enough,then go for it-you'll hear difference
one ,often forgotten ,human category is "good enough" ;
I hate that usually,but in technical world that is rule worth remembering
regarding leds....
looks logical to me to put at least 10mA through two led chain;
that will be with 1K8 to 2K2 resistor to ground (instead original of 4K75 in NP's 9V zenner case)
😕
looks logical to me to put at least 10mA through two led chain;
that will be with 1K8 to 2K2 resistor to ground (instead original of 4K75 in NP's 9V zenner case)
😕
LEDs regulator
Choky that was correct again. I had to adjust the ohms in this 4.75 K ohm position to a lower value as you had stated.
I find for better stability, I might adjust this 4.75 K ohm to arrive at 3.3 volts for the voltage reference. I think this will be more stable for all designs. I think a 5K pot in this position helps adjust initially and then I could stick in a fixed resister.
I am taking a break on this amp. I will try the compensation caps later this week, when I am more motivated. Two weekends of hauling amps over to Mark's has gotten me tired for the time being. I do have access to test equipment at home from my brother, so I plan this week checking the compensation caps. I think it should be close to being finished by this next weekend.
Mark is not planning on any more GTG for a couple of months. I have some new heat tunnels with some very quiet fans, I would like to try out with my Alephs and Zen version 9. Mark has talked about a piggy back board to hook up the jfet conversion. This would make things easy to even try Choky's bjf idea as a current source too.
Bill
choky said:regarding leds....
looks logical to me to put at least 10mA through two led chain;
that will be with 1K8 to 2K2 resistor to ground (instead original of 4K75 in NP's 9V zenner case)
😕
Choky that was correct again. I had to adjust the ohms in this 4.75 K ohm position to a lower value as you had stated.
I find for better stability, I might adjust this 4.75 K ohm to arrive at 3.3 volts for the voltage reference. I think this will be more stable for all designs. I think a 5K pot in this position helps adjust initially and then I could stick in a fixed resister.
I am taking a break on this amp. I will try the compensation caps later this week, when I am more motivated. Two weekends of hauling amps over to Mark's has gotten me tired for the time being. I do have access to test equipment at home from my brother, so I plan this week checking the compensation caps. I think it should be close to being finished by this next weekend.
Mark is not planning on any more GTG for a couple of months. I have some new heat tunnels with some very quiet fans, I would like to try out with my Alephs and Zen version 9. Mark has talked about a piggy back board to hook up the jfet conversion. This would make things easy to even try Choky's bjf idea as a current source too.
Bill
Now utterly confused: J176; 2SJ176
Hello Folks,
Reading the above posts, there is talk of the J176 and the 2SJ176. Looking up lots of datasheets, it appears that the 2SJ176 is a MOSFET, and the J176 is a J-fet or an unspecified chopper or switch; the former in a TO-220 case, the latter in a TO92 case.
Bill, are you using the J176 as the constant current source or the differential pair or both?
Could you use the J176 (matched up nicely) as the differential pair?
Regards,
George.
Hello Folks,
Reading the above posts, there is talk of the J176 and the 2SJ176. Looking up lots of datasheets, it appears that the 2SJ176 is a MOSFET, and the J176 is a J-fet or an unspecified chopper or switch; the former in a TO-220 case, the latter in a TO92 case.
Bill, are you using the J176 as the constant current source or the differential pair or both?
Could you use the J176 (matched up nicely) as the differential pair?
Regards,
George.
Re: Now utterly confused: J176; 2SJ176
I was puzzled too;
look up thread where I posted two pdfs-one for 2SJ and one for J;
hehe
Bill use J176.......so just forget 2SJ.....
GeorgeBoles said:
I was puzzled too;
look up thread where I posted two pdfs-one for 2SJ and one for J;
hehe
Bill use J176.......so just forget 2SJ.....
Re: Now utterly confused: J176; 2SJ176
Yes, I am using the j176 from http://www.allelectronics.com/cgi-bin/item/J176/550/P-CHANNEL_J-FET_TO-92_.html.
They are .20 cents a piece or 5 for $1.00. The j176 are rated either 35 mA from memory versus the 2sj109 rated at 20 mA max I recall.
When I looked at the pdf there were other jfets such as the j174 rated 135 mA. which is a lot higher than my j176 rated at 35 mA.
So, perhaps you could buy some of those elsewhere and try. They would not need to be matched, but it would keep the current source a jfet with more safety range for the current source jfet. I have been running mine about 25 or 26 mA and the jfet seems to be holding up so far.
I am currently still using all three j176 for the current source and differential LTP.
I would recommend 50 to 100 j176 from Allelectronics for matching if you go with those.
I currently have removed the .001 uf ceramic oscillation cap and also the 10 pF feedback bypass cap and have just last night tried removing the dc coupled capacitor. It sounded nice, but was too unstable on the DC offset. It varied plus or minus 25 to 30 mV without this cap. I also could not adjust the AC current gain with that cap missing, I found out.
So, I tried instead of my 2.2 uF film cap a smaller .22 MKT uF film cap and it sounded very nice compared to this other capacitor. I am going to continue trying some different capacitors in this dc feedback capacitor's position.
What is the best or most transparent capacitor? Anyone?
I was amazed how the amp sounded with no caps in the signal path anywhere except for the two 220 uF capacitors around the mpsa18 fet.
But I need the dc coupled capacitor in order to adjust the dc offset though. The amp is a lot more stable even with the .22 uF. I would like to keep trying smaller values to see if the sound is more transparent, but more stable on the DC offset.
Bill
GeorgeBoles said:
Yes, I am using the j176 from http://www.allelectronics.com/cgi-bin/item/J176/550/P-CHANNEL_J-FET_TO-92_.html.
They are .20 cents a piece or 5 for $1.00. The j176 are rated either 35 mA from memory versus the 2sj109 rated at 20 mA max I recall.
When I looked at the pdf there were other jfets such as the j174 rated 135 mA. which is a lot higher than my j176 rated at 35 mA.
So, perhaps you could buy some of those elsewhere and try. They would not need to be matched, but it would keep the current source a jfet with more safety range for the current source jfet. I have been running mine about 25 or 26 mA and the jfet seems to be holding up so far.
I am currently still using all three j176 for the current source and differential LTP.
I would recommend 50 to 100 j176 from Allelectronics for matching if you go with those.
I currently have removed the .001 uf ceramic oscillation cap and also the 10 pF feedback bypass cap and have just last night tried removing the dc coupled capacitor. It sounded nice, but was too unstable on the DC offset. It varied plus or minus 25 to 30 mV without this cap. I also could not adjust the AC current gain with that cap missing, I found out.
So, I tried instead of my 2.2 uF film cap a smaller .22 MKT uF film cap and it sounded very nice compared to this other capacitor. I am going to continue trying some different capacitors in this dc feedback capacitor's position.
What is the best or most transparent capacitor? Anyone?
I was amazed how the amp sounded with no caps in the signal path anywhere except for the two 220 uF capacitors around the mpsa18 fet.
But I need the dc coupled capacitor in order to adjust the dc offset though. The amp is a lot more stable even with the .22 uF. I would like to keep trying smaller values to see if the sound is more transparent, but more stable on the DC offset.
Bill
Re: Re: Now utterly confused: J176; 2SJ176
you can't go bellow 0,68 UF,without loosing bass;
mentioned 0,68 is good for some 10Hz cornering
BillWW said:
you can't go bellow 0,68 UF,without loosing bass;
mentioned 0,68 is good for some 10Hz cornering
Capacitor on Balanced Negative Input
Hello again, Choky.
Looking at post #144, you have given a little schematic for a balanced input for Babbelfish.
You have put a capactor on the -In, as there is in the original Alephs. For the Alephs, it is 220uF, but would it need to be much smaller with your setup with the higher impedances?
If I use you balanced inputs:
1. Would the capacitor be about 4u7?
2. Should I delete C3 (4u7) and R8 (22k) to earth?
3. Should I also put in a couple of Zeners to earth as well, as on the + Input and in the original Alephs?
I am just using logic and pattern recognition here with no electronics design experience ... as is probably obvious, and there are just one or two more changes than I can get my brain around.
Regards,
George.
Hello again, Choky.
Looking at post #144, you have given a little schematic for a balanced input for Babbelfish.
You have put a capactor on the -In, as there is in the original Alephs. For the Alephs, it is 220uF, but would it need to be much smaller with your setup with the higher impedances?
If I use you balanced inputs:
1. Would the capacitor be about 4u7?
2. Should I delete C3 (4u7) and R8 (22k) to earth?
3. Should I also put in a couple of Zeners to earth as well, as on the + Input and in the original Alephs?
I am just using logic and pattern recognition here with no electronics design experience ... as is probably obvious, and there are just one or two more changes than I can get my brain around.
Regards,
George.
George,during my sin bin days,I send schmtc at your private mail (on stolen antiques site) ;
there is no answer from you........
did you received that?
there is no answer from you........
did you received that?
Sin bins and my e-mail
Dear Choky,
Actually, I do not recall seeing your e-mail, and I was really looking out for it then!
However, your post just now has answered all my questions. I am just sketching up a "quick" board now which should work with my available heatsink and enclosures, and once I get some SJ109s I will probably make up a couple of channels of the Babbelfish.
By the way, I like the name Babbelfish 🙂 You have an excellent imagination, and twisted since of humour.
Regards,
George.
Dear Choky,
Actually, I do not recall seeing your e-mail, and I was really looking out for it then!
However, your post just now has answered all my questions. I am just sketching up a "quick" board now which should work with my available heatsink and enclosures, and once I get some SJ109s I will probably make up a couple of channels of the Babbelfish.
By the way, I like the name Babbelfish 🙂 You have an excellent imagination, and twisted since of humour.
Regards,
George.
Re: Sin bins and my e-mail
hehe
tnx,mate
(I'm blushing now 😉 )
but-for me most impressive thing is how bloody simple and elegant is that construction.......I don't have intention to be just just another NP's
follower ,but HIS sense for humor and practicity (in same time) is what impress me all the time,looking at his gadgets.....
GeorgeBoles said:
hehe
tnx,mate
(I'm blushing now 😉 )
but-for me most impressive thing is how bloody simple and elegant is that construction.......I don't have intention to be just just another NP's
follower ,but HIS sense for humor and practicity (in same time) is what impress me all the time,looking at his gadgets.....
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