attached is a transfomer coupled anode follower circuit from an AudioNote DAC (2.1x BAL).
the original capacitance connected to the cathode pins of E188CC is 470uF.
I was thinking of trying two BG N 470uF caps in super E: 940uF.
The circuit is hardwired however and I'd rather get it right the first time.
What does changing this capacitance do technically?
What does changing this capacitance do sonically?
Thank you to anyone who responds.
the original capacitance connected to the cathode pins of E188CC is 470uF.
I was thinking of trying two BG N 470uF caps in super E: 940uF.
The circuit is hardwired however and I'd rather get it right the first time.
What does changing this capacitance do technically?
What does changing this capacitance do sonically?
Thank you to anyone who responds.
An externally hosted image should be here but it was not working when we last tested it.
Hi Joseph,
looks like a common cathode buffer using parallel triode sections, with self bias mmm. anyway the caps I take it you are referring to are bypass capacitors accross the 180R cathode resistor. the value is chosen to effectivly increase the AC gain ie audio gain and mostly effects the lower frequency response. that is the point is where Cx reactance equals the cathode resistance. so increasing the value effectivly decreases the low frequency response, to a point.
thats the technical.
In reality I'm not sure if this translates to better sound given that it is large electrolytic in the the signal source and some people would say it would be better avoided.
what you have 470uf Cx @ 20hz ~ 17r almost 1/10 of Rk
after you change it to 940 Cx @20hz ~ 8.5r almost 1/20 Rk
Personally I don't think I could tell the difference.
looks like a common cathode buffer using parallel triode sections, with self bias mmm. anyway the caps I take it you are referring to are bypass capacitors accross the 180R cathode resistor. the value is chosen to effectivly increase the AC gain ie audio gain and mostly effects the lower frequency response. that is the point is where Cx reactance equals the cathode resistance. so increasing the value effectivly decreases the low frequency response, to a point.
thats the technical.
In reality I'm not sure if this translates to better sound given that it is large electrolytic in the the signal source and some people would say it would be better avoided.
what you have 470uf Cx @ 20hz ~ 17r almost 1/10 of Rk
after you change it to 940 Cx @20hz ~ 8.5r almost 1/20 Rk
Personally I don't think I could tell the difference.
Hi Joseph
I re read this and it made sense at the time but!
so increasing the value effectively decreases the low frequency response, to a point.
decreases the -3db point not the low frequency response so should read
so increasing the value effectively improves the low frequency response, to a point.
Robert
I re read this and it made sense at the time but!
so increasing the value effectively decreases the low frequency response, to a point.
decreases the -3db point not the low frequency response so should read
so increasing the value effectively improves the low frequency response, to a point.
Robert
thanks for the help, Robert.
now, say I'm using 470uF BlackGate N, non-polar, 'completely symetrical', capacitors and have accidentally reversed the leads, hooking up the +, long lead, to the ground, and the -, short lead to the signal.
I don't feel like redoing it..
now, say I'm using 470uF BlackGate N, non-polar, 'completely symetrical', capacitors and have accidentally reversed the leads, hooking up the +, long lead, to the ground, and the -, short lead to the signal.
I don't feel like redoing it..
Hi Joseph,
Ok I don't know that brand/type, however if it is a non polorized cap there should be no notion of polarity. the long and short leads are simply a function of manufacture i.e. same assembly as regular caps.
incidently is 470uf the standard value?
Ok I don't know that brand/type, however if it is a non polorized cap there should be no notion of polarity. the long and short leads are simply a function of manufacture i.e. same assembly as regular caps.
incidently is 470uf the standard value?
Hi,
Since the cap is a non-polar type there is no actual polarity so from a mere electrical POV it doesn't really matter which end's up....
Mind you, those Black Gates defy all laws of physics so be ware....
However, one of the leads is connected to a shielding foil which is directional. You'd want that foil connected to ground (-) or it won't have much of a shielding effect.
No big deal either way but just so you know.
The Jelmax "Tech sheets" are probably written by people lacking any technical knowledge, stink at English or any random combination of the above.
IOW, things can get confusing................
Now, regarding your question about "Super Eing" the bypass cap(s), assuming that's what it is as my reading of Modigliani paintings sux big time, I wouldn't bother.
There must be better places to waste money on..... Must be.
Besides, if you put two caps in series the total capacitance does not double but halves...
Unless the kids at Jelmax pulled a magic rabbit that is, in which case the value would remain the same. At best.
It's been a while since I last amused myself wading through their technobabble so you'd better measure the actual capacitance before you hook up those caps that way.....
Did I confuse anyone?? Probably just myself......................
Cheers, 😉
Since the cap is a non-polar type there is no actual polarity so from a mere electrical POV it doesn't really matter which end's up....
Mind you, those Black Gates defy all laws of physics so be ware....
However, one of the leads is connected to a shielding foil which is directional. You'd want that foil connected to ground (-) or it won't have much of a shielding effect.
No big deal either way but just so you know.
The Jelmax "Tech sheets" are probably written by people lacking any technical knowledge, stink at English or any random combination of the above.
IOW, things can get confusing................
Now, regarding your question about "Super Eing" the bypass cap(s), assuming that's what it is as my reading of Modigliani paintings sux big time, I wouldn't bother.
There must be better places to waste money on..... Must be.
Besides, if you put two caps in series the total capacitance does not double but halves...
Unless the kids at Jelmax pulled a magic rabbit that is, in which case the value would remain the same. At best.
It's been a while since I last amused myself wading through their technobabble so you'd better measure the actual capacitance before you hook up those caps that way.....
Did I confuse anyone?? Probably just myself......................
Cheers, 😉
with two BG N's in series, the capacitance doubles. I've measured it.
BG N's may be a waste of money, but they sure sound good.
BG N's may be a waste of money, but they sure sound good.
Hi Joseph,
You indicated that the caps would be in parallel as per the drawing, what I am intrigued with is the sub 1 hz -3db point your trying to achieve using increased k bypass capacitance. What was the original value? I'd guess somewhere between 47uf and 100uf??
Have you considered this might cause issues with short term drift, perhaps saturation of the O/P transformer core I don't know the specs on the units fitted.
Sy had a good response on this subject about a month ago he indicated too much LF response might in itself cause problems and was a good read.
fdegrove,
I didn't realize these black gate caps were sooo expensive this means I have to choose between ofc cable or BG caps ;o((
Robert
You indicated that the caps would be in parallel as per the drawing, what I am intrigued with is the sub 1 hz -3db point your trying to achieve using increased k bypass capacitance. What was the original value? I'd guess somewhere between 47uf and 100uf??
Have you considered this might cause issues with short term drift, perhaps saturation of the O/P transformer core I don't know the specs on the units fitted.
Sy had a good response on this subject about a month ago he indicated too much LF response might in itself cause problems and was a good read.
fdegrove,
I didn't realize these black gate caps were sooo expensive this means I have to choose between ofc cable or BG caps ;o((
Robert
Joseph0 said:
are these special type of caps? what happens in their capacitance when they are in parallel?
thanks!
JojoD
Hi,
Thing is you see, they're not really in series and they're not really non-polar either.....
Magic, right?
What you do with this Super E connection is similar to what some of us did to create a better cap using electrolytics for loudspeaker X-overs long before non-polar electrolytics were available.
I'm talking like more than thirty years ago already..........
Whatever you decide to do, keep in mind that there's little point in doubling the existing cap's value.
Little point in using the Super E connection method either if you already have a BG-N type cap across the cathode resistor.
Be ware of the voltage across the cap as well, provide for a reasonable safety margin like roughly 30% over the static cathode voltage.
I honestly don't know how such a connection behaves voltagewise and I doubt Jelmax have it covered somewhere.
Did I say they were a waste of money?
Did I say they sounded bad?
No, I didn't.
I just wanted to make you aware of what it was you're doing with a spare cap that may find better use elsewhere relative to what you intend of doing with it here. That's all.😉
I hope I learned something....
Cheers, 😎
Thing is you see, they're not really in series and they're not really non-polar either.....
Magic, right?
What you do with this Super E connection is similar to what some of us did to create a better cap using electrolytics for loudspeaker X-overs long before non-polar electrolytics were available.
I'm talking like more than thirty years ago already..........
Whatever you decide to do, keep in mind that there's little point in doubling the existing cap's value.
Little point in using the Super E connection method either if you already have a BG-N type cap across the cathode resistor.
Be ware of the voltage across the cap as well, provide for a reasonable safety margin like roughly 30% over the static cathode voltage.
I honestly don't know how such a connection behaves voltagewise and I doubt Jelmax have it covered somewhere.
Did I say they were a waste of money?
Did I say they sounded bad?
No, I didn't.
I just wanted to make you aware of what it was you're doing with a spare cap that may find better use elsewhere relative to what you intend of doing with it here. That's all.😉
I hope I learned something....
Cheers, 😎
I meant when connected like this:
An externally hosted image should be here but it was not working when we last tested it.
[QUOTE fdegrove]There must be better places to waste money on..... Must be.[/QUOTE]
maybe you were saying Modigliani paintings are a waste of money. : ^ P
maybe you were saying Modigliani paintings are a waste of money. : ^ P
An externally hosted image should be here but it was not working when we last tested it.
Hi,
That's what they call Super E?
A connection like that would be electrically equal to 2 caps in //.
What you achieve with that, assuming two identical caps, is twice the capacitance and whatever directionality each cap would have would now be cancelled out.
Voltage rating is the same as that of a single cap.
Whatever internal shield was present is now connected individually, one at the input, the other at the output rendering only the shield that goes to the ground end of things effective.
I'm still confused...How 'bout you?
Cheers, 😉
That's what they call Super E?
A connection like that would be electrically equal to 2 caps in //.
What you achieve with that, assuming two identical caps, is twice the capacitance and whatever directionality each cap would have would now be cancelled out.
Voltage rating is the same as that of a single cap.
Whatever internal shield was present is now connected individually, one at the input, the other at the output rendering only the shield that goes to the ground end of things effective.
I'm still confused...How 'bout you?
Cheers, 😉
Joseph0 said:
so that means the caps would be in parallel and not in series. no wonder the capacitance increased.
thanks man!
I decided to keep the capacitance at 470uF.
Here are some photos (the circuit includes part of an auto de-emphasis circuit along with the circuit on diagram):
the parts of the d/a section, minus the output transformers:
the long leadout wires are for LEDs.
and yes, I used copper foil oil caps in the de-emphasis filter. I made the decision to do this before I understood their purpose (i originally thought they were part of the analogue filter).
now I can listen to certain pink floyd cds and 1 in 150 others in need of de-emphasis..like never before.
they make a nice fit however.
I hope no one is getting emails for my edits. I apologize if so.
Here are some photos (the circuit includes part of an auto de-emphasis circuit along with the circuit on diagram):
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
the parts of the d/a section, minus the output transformers:
An externally hosted image should be here but it was not working when we last tested it.
the long leadout wires are for LEDs.
and yes, I used copper foil oil caps in the de-emphasis filter. I made the decision to do this before I understood their purpose (i originally thought they were part of the analogue filter).
now I can listen to certain pink floyd cds and 1 in 150 others in need of de-emphasis..like never before.
they make a nice fit however.
I hope no one is getting emails for my edits. I apologize if so.
robert,
the following links may help explain the use of the higher cathode capacitance on the anode follower.
The article in the first link uses a 1000uF cap connected to the cathode, Cc in the diagram.
http://members.chello.nl/~m.heijligers/DAChtml/Analogue/Amplification.html
more on the anode follower may be found here:
http://www.tubecad.com/october99/page8.html
I believe you were thinking the cathode to be the output, but I'm certainly not an expert.
the following links may help explain the use of the higher cathode capacitance on the anode follower.
The article in the first link uses a 1000uF cap connected to the cathode, Cc in the diagram.
http://members.chello.nl/~m.heijligers/DAChtml/Analogue/Amplification.html
more on the anode follower may be found here:
http://www.tubecad.com/october99/page8.html
I believe you were thinking the cathode to be the output, but I'm certainly not an expert.
Hi,
What?
Where on earth do you read that??
Find me a value for Rc where it would require a 1000uF cathode bypass cap if F0 = 10Hz using the following formula:
C= 1/(63.Rc)
Second note:
There's no cap like no cap.
Small caps usually sound better than big ones (due to increased R/C time constants of the bigger ones)
A little local feedback does less damage than global loops so why not use some where appropriate?
If the cathode is taken as the output node, putting a cap across the cathode resistor effectively shunts the AC component to ground, ergo no useable output.......
Sorry if I sound like a pedantic pain in the behind. Just trying to help.
Ciao, 😉
What?
Where on earth do you read that??
Find me a value for Rc where it would require a 1000uF cathode bypass cap if F0 = 10Hz using the following formula:
C= 1/(63.Rc)
Second note:
There's no cap like no cap.
Small caps usually sound better than big ones (due to increased R/C time constants of the bigger ones)
A little local feedback does less damage than global loops so why not use some where appropriate?
If the cathode is taken as the output node, putting a cap across the cathode resistor effectively shunts the AC component to ground, ergo no useable output.......
Sorry if I sound like a pedantic pain in the behind. Just trying to help.
Ciao, 😉
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