Re: "Zobel"
If you don't like the name Zobel network you can call it a
Boucehrot cell, which is sometimes done. However, they
seem to be interchangeable terms so both are perfectly
fine to use whether at an amp output or inside a speaker
www.rane.com/par-z.html#Zobel
1audio said:
If you don't like the name Zobel network you can call it a
Boucehrot cell, which is sometimes done. However, they
seem to be interchangeable terms so both are perfectly
fine to use whether at an amp output or inside a speaker
www.rane.com/par-z.html#Zobel
Peter Daniel said:
Thanks Peter 😉
This is interesting. I can't say I observed any real difference between the two topologies, which was kind-off disappointing. I was perhaps expecting the lower value gain-setting resistors to help reduce the pick up, but this shows that the "way in" for RF isn't via the -ve input. Adding a Zobel made quite a difference to the NI version - I didn't try it with the inverting amp.
So, I found that the route is definitely via the speaker cables in my case - as moving the phone around demonstrates quite well. I can't provoke it via the input leads, but then I use an input filter.
For reference, my old Musical Fidelity A1 was excellent in this regard - the only way to get any sort of pickup at all was to hold the phone near to the MM cartridge! Note that this amp had a modified preamp with, guess what - an input filter 😉
It also has a Zobel 😉
I'd be interested in hearing other peoples experience with this - I guess it would also be useful input for Peter too 😉
Cheers,
Mark
mhennessy said:
The difference in my case is probably more related to different system setups for both amps (I and NI). I will do more testing today and will report.
Please also notice, I already posted previously that in one of my systems it seemed to me like Zobel brought sonic improvement, however, in the other system it actually brought degradation. So I'm not really inclined one way or another, but would rather try to investigate the matter in as many systems as possible.
I included set of jumpers with the amps that went to the show, so maybe they'll check it there as well.
Peter Daniel said:
I interprete that you still advocate no Zobel.
Why don't you think about customer's satisfaction with both technical and sonical aspects? Your customer would appreciate it.
Anyhow, this thread is more interesting than "HowToLoseTheGuyWithin10Days."
Good luck.
JH
My main goal is best sonic presentation, even at the risk of misbehaving amp. Those amps are not your typical mainstream equipment, so some care is adviced when setting them up.
I still imagine that without Zobel they sound better, but I will do more extensive, field testing to know for sure. Like it or not, this thread was quite influential in that😉
I still imagine that without Zobel they sound better, but I will do more extensive, field testing to know for sure. Like it or not, this thread was quite influential in that😉
Hmm... well noted.
This thread motivates me to think that emotional logic could solve technial basic problem. I wonder whether it is ... or not.
JH
This thread motivates me to think that emotional logic could solve technial basic problem. I wonder whether it is ... or not.
JH
OSN anyone?
Well we can call the "Zobel" something else I suppose................
"In the amp it is not directly a function of a specific load impedance but used to compensate for the potential LC tank on the output when combining the RL isolation network with a pure capacitance." -DM
Series RL are becoming pretty extinct and are felt to be redundant with when a OSN is used on an amp. The R in parallel with the L is to damp the LC tank circuit of the output inductor and load capacitance. The speaker cable, usually responsible for most of the load capacitance is anything but a simple capacitance. As frequencies approach the 10s of MHz and above it really must be modeled as a mis-terminated transmission line. The audio frequency speaker impedances have given way to the complex (resistive and reactive) impedance of voice coil inductance, cross-over components, and internal wiring in the speaker.
Without an OSN on the amp the source impedance is an inductance within the frequency range where the amp has open loop voltage gain voltage greater than the closed loop gain (somewhat simplified of course, but a good approximation). At the point where the gain drops to unity, the amp's output impedance increases faster than a simple inductance (6dB per octave) due to the addition poles in the open loop response of the amp. The degree of deviation from a pure inductance at this point determines the phase margin and stability of the amp.
Just to make things even more interesting for the amp designer, the output inductance of the amp is a function of the current the amp is supplying or sinking. The open loop gain and the poles that determine the phase margin are also a function of both the resistive and reactive load impedance the amp sees.
Is it surprising that an output network is desired to swamp reactive loads and provide a predictable resistive load for the amp to work into at frequencies above the audio range and into the RF region?
I hope this gives a bit of insight as to why amps are speaker and cable sensitive and the Chip type amps tend to work better efficient speaker with high impedances (8 ohm rather than 4) where current swings (and the resulting changes in the amp's output frequencies with increasing current drive) are modest
and with an output stabilization network (OSN) which supplies a predictable resistive load at high frequencies.
Moderators can we please have an hour edit window so I can polish my post for clarity, good grammer, and additional info?
It would really help!
Well we can call the "Zobel" something else I suppose................
"In the amp it is not directly a function of a specific load impedance but used to compensate for the potential LC tank on the output when combining the RL isolation network with a pure capacitance." -DM
Series RL are becoming pretty extinct and are felt to be redundant with when a OSN is used on an amp. The R in parallel with the L is to damp the LC tank circuit of the output inductor and load capacitance. The speaker cable, usually responsible for most of the load capacitance is anything but a simple capacitance. As frequencies approach the 10s of MHz and above it really must be modeled as a mis-terminated transmission line. The audio frequency speaker impedances have given way to the complex (resistive and reactive) impedance of voice coil inductance, cross-over components, and internal wiring in the speaker.
Without an OSN on the amp the source impedance is an inductance within the frequency range where the amp has open loop voltage gain voltage greater than the closed loop gain (somewhat simplified of course, but a good approximation). At the point where the gain drops to unity, the amp's output impedance increases faster than a simple inductance (6dB per octave) due to the addition poles in the open loop response of the amp. The degree of deviation from a pure inductance at this point determines the phase margin and stability of the amp.
Just to make things even more interesting for the amp designer, the output inductance of the amp is a function of the current the amp is supplying or sinking. The open loop gain and the poles that determine the phase margin are also a function of both the resistive and reactive load impedance the amp sees.
Is it surprising that an output network is desired to swamp reactive loads and provide a predictable resistive load for the amp to work into at frequencies above the audio range and into the RF region?
I hope this gives a bit of insight as to why amps are speaker and cable sensitive and the Chip type amps tend to work better efficient speaker with high impedances (8 ohm rather than 4) where current swings (and the resulting changes in the amp's output frequencies with increasing current drive) are modest
and with an output stabilization network (OSN) which supplies a predictable resistive load at high frequencies.
Moderators can we please have an hour edit window so I can polish my post for clarity, good grammer, and additional info?
It would really help!
Re: OSN anyone?
Thinking about it now, when I'm also a subject to those limitations, it seems like a very good idea.😉
Fred Dieckmann said:
Thinking about it now, when I'm also a subject to those limitations, it seems like a very good idea.😉
Easyamp said:
Given the GainKlunne's evolution it is a good thing that, with the chips under discussion, these chips do not give you access to what a discrete circuit does, specifically feedback around the Vas, typically to its input base or the inverting input of the diff pair. While the ChipCobblers(tm), may view the sum total of the feedback as that single global connection to the inverting input, it is not. It is simply that National has made those decisions for you, which Bodes well. With a discrete circuit, the plot thickens, as you've far more variables to consider for optimization (or a local gradient search). Some wacky discrete designers will even implement the 'internal' feedback so that the amp will oscillate with no load connected unless a Zoebel/Boucheret is connected. A Zoebel is very much in the feedback. Obviously, National has chosen a conservative internal feedback scheme, which yeilds a stable amp into many loads, even without a zoebel (or load) present.
This discussion very much needs to be in the Chip Forum, as those designers of discrete feedback amps, far more knowledgeable than myself, already accept what is under dispute here, they already understand those phase margin thingamabobs, which many have patiently and graciously???, repeatedly explained.
Ain't misbehaving ... I'm savin' my love for you
Do you really believe a misbehaving amp is giving the best sonic presentation!? Will you please explain this? Or you think this is cut and dryed, either or situation, that is where the amp sounds glorious or awful depending on the system set up? I am mystified by what you mean and surely am not the only one............ 😕
Peter Daniel said:
Do you really believe a misbehaving amp is giving the best sonic presentation!? Will you please explain this? Or you think this is cut and dryed, either or situation, that is where the amp sounds glorious or awful depending on the system set up? I am mystified by what you mean and surely am not the only one............ 😕
Attachments
Peter Daniel said:
Haha...
Do not be misunderstood that everybody will follow your sense of music and emotion. And, you are very clever to avoid going through the point to reach your advocate.
All the best!
JH
Re: Ain't misbehaving ... I'm savin' my love for you
I'm sure you are mystified. I didn't say a misbehaving amp gives best sonic presentation. I said I very rarely see a misbehaving amp, and when it does, it can be fixed quite easily. For the record, I experienced that misbehaving case only once (and even then a circuit under discussion didn't provide expected solution), so I'm not loosing any sleep over that. Your milage may vary.
Fred Dieckmann said:
I'm sure you are mystified. I didn't say a misbehaving amp gives best sonic presentation. I said I very rarely see a misbehaving amp, and when it does, it can be fixed quite easily. For the record, I experienced that misbehaving case only once (and even then a circuit under discussion didn't provide expected solution), so I'm not loosing any sleep over that. Your milage may vary.
Did he really say that?
C'mon, Frank......are you trying to tell us that cell phones cause less interference these days?
Not unless their output power has been lowered.
Which I doubt that it has.
Maybe you should leave the comic reilef to us pros. [joke]
Hey, Peter..........find someone who has a 6- or 2-meter "handie talkie". Key that sucker up close to your amp. Then tell us about EMC susceptibility.
Jocko
C'mon, Frank......are you trying to tell us that cell phones cause less interference these days?
Not unless their output power has been lowered.
Which I doubt that it has.
Maybe you should leave the comic reilef to us pros. [joke]
Hey, Peter..........find someone who has a 6- or 2-meter "handie talkie". Key that sucker up close to your amp. Then tell us about EMC susceptibility.
Jocko
Yell loudly and STILL carry a big stick.
I think it is because they talk more quietly and calmly than we do when we scream on the phone to each other about the state of the forum and the world in general. I wish you guys could he jocko yell.
Ask jam ............ he has heard it over the phone and in person. I,
on the other hand am so shy and timid that people often can't hear me on the phone......... right jam?
JOCKO COME WATCH BASEaBALL AND BRING YOUR TEST DISK SO I CAN TELL WHAT TONE GOES WITH WHAT TRACK! I swear you did it on purpose!
Jocko Homo said:
I think it is because they talk more quietly and calmly than we do when we scream on the phone to each other about the state of the forum and the world in general. I wish you guys could he jocko yell.
Ask jam ............ he has heard it over the phone and in person. I,
on the other hand am so shy and timid that people often can't hear me on the phone......... right jam?
JOCKO COME WATCH BASEaBALL AND BRING YOUR TEST DISK SO I CAN TELL WHAT TONE GOES WITH WHAT TRACK! I swear you did it on purpose!
Re: Re: Ain't misbehaving ... I'm savin' my love for you
Rolling on the floor laughing after spraying Coke Cola out my noise.
And everyone thinks Jocko and I are the only ones ever joking on the forum.
Peter Daniel said:
Rolling on the floor laughing after spraying Coke Cola out my noise.
And everyone thinks Jocko and I are the only ones ever joking on the forum.
Hi,
You should try a real trioded cascode in that cellular for grins...😀
Nah...Could it be due to a change in EU regulations over the past five years or so?
More likely it's just because I moved out of Brussels into a rural area but nonetheless I'm damn glad I don't have to suffer these RF breakthroughs anymore...
Taxicabs were even worse than cellular phones....Are they really all run by Danny De Vito? I wonder...
That explains it, I guess...They forgot to equip him with a proper Zobel network thingie...
Cheers,😉
You should try a real trioded cascode in that cellular for grins...😀
Nah...Could it be due to a change in EU regulations over the past five years or so?
More likely it's just because I moved out of Brussels into a rural area but nonetheless I'm damn glad I don't have to suffer these RF breakthroughs anymore...
Taxicabs were even worse than cellular phones....Are they really all run by Danny De Vito? I wonder...
That explains it, I guess...They forgot to equip him with a proper Zobel network thingie...
Cheers,😉
After all these patient attempts by Fred and others to teach
about Zobel filters, I can't help being reminded of this old
Snoopy strip I sent Jocko the other day when talking about
someb... ehrm something
else.
"I have just taught the dog to talk"
"Have you? Say something, dog!" ...silence... But it doesn't say anything?"
"I only said I had taught the dog to talk, not that the dog had learnt to talk."
Unfortunately I've lost my copy of the original cartoon, but
I am sure jam will find it for us. 🙂
about Zobel filters, I can't help being reminded of this old
Snoopy strip I sent Jocko the other day when talking about
someb... ehrm something
else."I have just taught the dog to talk"
"Have you? Say something, dog!" ...silence... But it doesn't say anything?"
"I only said I had taught the dog to talk, not that the dog had learnt to talk."
Unfortunately I've lost my copy of the original cartoon, but
I am sure jam will find it for us. 🙂
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