STOXX - I have done as you suggested.
I find the "schematic" you so generously supplied has some different values than the standard.
You have different values of capacitors for C1 and C2. I am not familiar enough with TSpice to know if this is a balanced or single ended input - for all I know it is single ended and difference in the caps means nothing like it would with a balanced input. My assumption since I do not know.
I can run a frequency sweep and it looks like one would expect a filter to look like with C1 and C2 at 0.01uF.
How does one find out if this has problems? Sorry to be so helpless but I have no idea how to verify if this is OK or bad.
Could you direct me to where I can find out more about this?
THANKS and take care,
I find the "schematic" you so generously supplied has some different values than the standard.
You have different values of capacitors for C1 and C2. I am not familiar enough with TSpice to know if this is a balanced or single ended input - for all I know it is single ended and difference in the caps means nothing like it would with a balanced input. My assumption since I do not know.
I can run a frequency sweep and it looks like one would expect a filter to look like with C1 and C2 at 0.01uF.
How does one find out if this has problems? Sorry to be so helpless but I have no idea how to verify if this is OK or bad.
Could you direct me to where I can find out more about this?
THANKS and take care,
Hi Rick,
The DIY FE input may be single ended or balanced. When C2 is grounded the input is single ended. For balanced input, In+ is at C1 and In- is at C2.
When changing the high pass frequency both C1 and C2 should be changed, and they should both be the same value, regardless of whether you are using single ended or balanced input.
Note that the ratio of R3/R1 and R4/R2 is the gain ratio. R2 and R4 are also part of the high pass filter so any change to R2 and R4 will have an effect on the high pass frequency.
The DIY FE input may be single ended or balanced. When C2 is grounded the input is single ended. For balanced input, In+ is at C1 and In- is at C2.
When changing the high pass frequency both C1 and C2 should be changed, and they should both be the same value, regardless of whether you are using single ended or balanced input.
Note that the ratio of R3/R1 and R4/R2 is the gain ratio. R2 and R4 are also part of the high pass filter so any change to R2 and R4 will have an effect on the high pass frequency.
I am also interested to use this FE with DIY Biamp 6-24 active crossover but I cannot figure out on how to connect them to the same power supply. The issue is the common GND point. The DIY biamp needs single 24V PSU with a virtual GND at 12V but the DIY FE 2022 is using dual 24V PSU with the GND at 0V. Can I use them together with one power supply?
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Hello dansa69,
the FE2022 can also run from a single-ended powersupply (+24 V DC - GND) as well the 6-24 AXO uses a single ended supply.
The FE2022 (power input) would be connected like:
V+ to PSU +24 V
VG not connected (virtual ground - made by R11//C4 and R12//C5)
V- to PSU ground
Nothing else should be connected to VG (FE2022) - it will run anywhere around +12 V DC!
Cheers
Dirk
the FE2022 can also run from a single-ended powersupply (+24 V DC - GND) as well the 6-24 AXO uses a single ended supply.
The FE2022 (power input) would be connected like:
V+ to PSU +24 V
VG not connected (virtual ground - made by R11//C4 and R12//C5)
V- to PSU ground
Nothing else should be connected to VG (FE2022) - it will run anywhere around +12 V DC!
Cheers
Dirk
Ha, I used smps medical type with +/- for a mc amplifier. On that ‘level’ I could hear a faint whining = the two oscilaters had a different drum beat, and I heard the interference tone rising and dropping. . . Earth? The medical was supposed not to ‘touch earth’ nowhere. But your story gives me a clue.
Dear Ben Mah,
I have used FE2022 with a balanced input. I know it can be configured for balanced or single-ended.
I am speaking of the LTSpice schematic that STOXX provided.
Not knowing enough about LTSpice I cannot tell which kind of input he has used in this schematic.
It looks single ended to me especially since he used different values of capacitors.
I have used FE2022 with a balanced input. I know it can be configured for balanced or single-ended.
I am speaking of the LTSpice schematic that STOXX provided.
Not knowing enough about LTSpice I cannot tell which kind of input he has used in this schematic.
It looks single ended to me especially since he used different values of capacitors.
He had C2 grounded so yes, it is single ended input.
However the capacitor values should not be different. I do not know why he had them different. I believe they should be the same regardless of the input type.
Since you have the simulation model, you can try both cases, same capacitor value and different capacitor values when the input is single ended, and compare results.
I find LTSpice simulations can be very educational. 🤓
However the capacitor values should not be different. I do not know why he had them different. I believe they should be the same regardless of the input type.
Since you have the simulation model, you can try both cases, same capacitor value and different capacitor values when the input is single ended, and compare results.
I find LTSpice simulations can be very educational. 🤓
THANKS for the confirmation. He also had a different value for R6 - easy enough to fix.
Not that the input configuration has much to do with what I am investigating!
I am curious if using 0.01 uF caps as the balanced input caps (this is for a tweeter) would have any deleterious effects on the quality of the line stage.
I see no need to amplify the region I am cutting off but then ... If I knew I wouldn't be asking!
I would greatly appreciate your opinion, Ben Mah.
I bet the simulations are educational - but I have no idea how to get the thing to do the truly educational part. I will keep trying, though.
What would one look at to discover whether a circuit change is good or bad?
Thanks and take care,
Not that the input configuration has much to do with what I am investigating!
I am curious if using 0.01 uF caps as the balanced input caps (this is for a tweeter) would have any deleterious effects on the quality of the line stage.
I see no need to amplify the region I am cutting off but then ... If I knew I wouldn't be asking!
I would greatly appreciate your opinion, Ben Mah.
I bet the simulations are educational - but I have no idea how to get the thing to do the truly educational part. I will keep trying, though.
What would one look at to discover whether a circuit change is good or bad?
Thanks and take care,
The capacitors work in conjunction with the resistors as a high pass filter. So the "deleterious" effect would be reduced low frequency response. But that is what you are after.
If you do not need gain, perhaps you can just use a high pass filter. Or a higher order filter. I do not have any experience with speaker cross-overs so I have no comments regarding filters/cross-overs.
With LTSpice, I treat circuits that I want to explore as a science experiment. I change resistor values to see their effect on currents and voltages at various points of the circuit. From that I have experimentally determined the function of the resistors in various applications. I have changed voltages and currents and observed their effects on output signal voltages and harmonic distortions. And changing components and observing frequency responses. There are many things that can be done experimentally. The key is to correlate the cause and effect and learn from that.
It reminds me of high school physics more than 50 years ago when we learned basic laws of physics using the experimental method. 🤓
If you do not need gain, perhaps you can just use a high pass filter. Or a higher order filter. I do not have any experience with speaker cross-overs so I have no comments regarding filters/cross-overs.
With LTSpice, I treat circuits that I want to explore as a science experiment. I change resistor values to see their effect on currents and voltages at various points of the circuit. From that I have experimentally determined the function of the resistors in various applications. I have changed voltages and currents and observed their effects on output signal voltages and harmonic distortions. And changing components and observing frequency responses. There are many things that can be done experimentally. The key is to correlate the cause and effect and learn from that.
It reminds me of high school physics more than 50 years ago when we learned basic laws of physics using the experimental method. 🤓
I DO need the gain.
I know that is what I assumed but wondered - due to something the GREAT ONE wrote to me in a note years ago about doing something similar to this in an amplifier and he was concerned about it affecting something other than just the bandwidth - I wish I could remember exactly - one of those things that haunts your memory but remains an incomplete thought.
I am in the midst of finishing them up and will listen for myself in a day or so - and take some measurements through my loudspeakers - the limit of my abilities when it comes to measurements.
One of these I plan on taking it ALL as seriously as you have. You are a light, Ben Mah, and an inspiration.
I know that is what I assumed but wondered - due to something the GREAT ONE wrote to me in a note years ago about doing something similar to this in an amplifier and he was concerned about it affecting something other than just the bandwidth - I wish I could remember exactly - one of those things that haunts your memory but remains an incomplete thought.
I am in the midst of finishing them up and will listen for myself in a day or so - and take some measurements through my loudspeakers - the limit of my abilities when it comes to measurements.
One of these I plan on taking it ALL as seriously as you have. You are a light, Ben Mah, and an inspiration.
I have been putting together the FE to use in front of a BA2 output stage. I opened the 8 matched jfets from punkydawgs (ordered last year) and discovered that they are 2SJ74s NOT 2SK170s. Return window closed almost a year ago. My bad that I did not check them when received - the bag was marked "N", not "P".
Is there a way to convert the board to use these P-channel jfets and a KSC1845(npn) and somehow salvage this effort? Use P-chan jfets instead of the J113s for the current sources and swap (+) and (-) power? I am newer to transistors being a really old tube guy.
Is there a way to convert the board to use these P-channel jfets and a KSC1845(npn) and somehow salvage this effort? Use P-chan jfets instead of the J113s for the current sources and swap (+) and (-) power? I am newer to transistors being a really old tube guy.
Also nothing wrong with using J113 instead of SK170. I have J113 in my DIY FE and it sounds great. On paper the SK170 version has lower distortion but the J113 version's distortion is low enough that perhaps the difference isn't audible for most listeners. 🤓
I did build the all J113 version and it was good, but not as good as other preamps/frontends that I have built. For me, it is not about lowest distortion - imaging and tonality of cymbals are the 2 first things on my listening list (it's a long list)🙂
Hoping that the Toshibas will push it up to that level for me.
Nothing wrong with the J113 version.
Hoping that the Toshibas will push it up to that level for me.
Nothing wrong with the J113 version.
Just having built a pair of FE2022s for the tweeter section of my speakers I do hear the same kind of things bsk is bothered about - along with them being surprisingly noisy even though set for 10 dB gain. Noisy compared to a CINEMAG transformer.
I have plenty of 2SK170s - would a resistor change be needed where the selected resistors are used?
I have plenty of 2SK170s - would a resistor change be needed where the selected resistors are used?
As I had mentioned I have built my DIY FE with J113, and I hear no noise at all from my 103dB sensitive speakers. If your setup is noisy there is something not right.
I also have no problem with imaging or cymbals but then perhaps I am not very critical, or perhaps different system, different sound. 🤓
I also have no problem with imaging or cymbals but then perhaps I am not very critical, or perhaps different system, different sound. 🤓
Thanks for your advice.
As I said: compared to the transformer - and the FE2022 does have 10 dB additional gain above the transformers which are used as a balanced to single ended adapter so an unfair comparison.
These are used in cascade with Rahul's SCG so there is a total of approx 28 dB gain. This drives a compression driver, alone, so the sensitivity is quite high.
It is certainly not obnoxious - I mainly listen to LPs so that noise swamps it. Just thought I would use the devices I have.
Still curious as to what value resistors would be needed. My 2SK170 are BL grade.
I have nothing against J113s! I have never had a complaint with them in Rahul's gain stage. I had compared 2SJ74 in exchange for the J175 in SCG and found the J175 was superior so this is not a case of TOSHIBA snobbery.
Just figured they would be quieter.
As I said: compared to the transformer - and the FE2022 does have 10 dB additional gain above the transformers which are used as a balanced to single ended adapter so an unfair comparison.
These are used in cascade with Rahul's SCG so there is a total of approx 28 dB gain. This drives a compression driver, alone, so the sensitivity is quite high.
It is certainly not obnoxious - I mainly listen to LPs so that noise swamps it. Just thought I would use the devices I have.
Still curious as to what value resistors would be needed. My 2SK170 are BL grade.
I have nothing against J113s! I have never had a complaint with them in Rahul's gain stage. I had compared 2SJ74 in exchange for the J175 in SCG and found the J175 was superior so this is not a case of TOSHIBA snobbery.
Just figured they would be quieter.
"Still curious as to what value resistors would be needed. My 2SK170 are BL grade."
I have 32 each 2SK170 previously used in a crossover as buffers. I want to repurpose into this front end.
They range from 10.9 to 11.86 IDSS, all of them have a pair at least.
If I use the lower 11 IDSS pairs, what should the value of R7 and R8 be? Or should I dig into my stash of 2SK170 for lower IDSS. (Just hate to waste these, with cut legs!)
Rush
I have 32 each 2SK170 previously used in a crossover as buffers. I want to repurpose into this front end.
They range from 10.9 to 11.86 IDSS, all of them have a pair at least.
If I use the lower 11 IDSS pairs, what should the value of R7 and R8 be? Or should I dig into my stash of 2SK170 for lower IDSS. (Just hate to waste these, with cut legs!)
Rush