I myself failed to see what is in LM3886 that is similar to CFB amps soundwise.
You must have been speaking to a salesman that either doesnt have a clue what he is talking about or simply promising you whatever to make a sale.
Here the folowing statement from Cyrus :
"The input signals are relay switched immediately as they enter the Cyrus Straight Line, ensuring maximum signal fidelity and effectively no X-talk between inputs. The propriety current-feedback amplifier design constitutes the basis of the Cyrus Straight Line. Our application of current feedback principles, rather than conventional voltage feedback methods, enables ultra-fast slewing of 700V/mS and negligibly low distortion at higher frequencies. The result is an exceptional sweetness and clarity in the mid-band with an attractive silky top end. Finally, an authoritative bass response with convincing scale and weight underpins the overall rendition of program material."
Like I said before Cyrus has only produced CFB amps since model 3.
Why not satisfy both cfb and vfb listeners ?
http://www.diyaudio.com/forums/solid-state/135122-wonderfull-sziklai-22.html#post3223807
My ears are delighted with 60db of CFB and 20 db of vfb
Also it is possible to equalise the cfb and vfb factor by making equal the ratios:
R15/R2 = R5/R8 .
If we want to have the cfb dominant we can decrease R15 to 10kohm for example and put in series a capacitor of 22uF to minimise the voltage drift in dc .
http://www.diyaudio.com/forums/solid-state/135122-wonderfull-sziklai-22.html#post3223807
My ears are delighted with 60db of CFB and 20 db of vfb
Also it is possible to equalise the cfb and vfb factor by making equal the ratios:
R15/R2 = R5/R8 .
If we want to have the cfb dominant we can decrease R15 to 10kohm for example and put in series a capacitor of 22uF to minimise the voltage drift in dc .
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Homemodder,
Like I said Cyrus Straight Line is CF, no doubt about that, but it seems that it was one time experiment, and I can not be sure that their products after that are CF unless I see schematics (which I do not have). How do you know that the latest incarnations of series 6 and 8 are CF? Do you have schematics? There is nowhere such claim from Cyrus. The only model for which CF is explicitly claimed is Straight Line.
Like I said Cyrus Straight Line is CF, no doubt about that, but it seems that it was one time experiment, and I can not be sure that their products after that are CF unless I see schematics (which I do not have). How do you know that the latest incarnations of series 6 and 8 are CF? Do you have schematics? There is nowhere such claim from Cyrus. The only model for which CF is explicitly claimed is Straight Line.
Nice idea to increase common mode rejection to CF amps.
Have a look to SSA on how to apply on symmetrical topologies.
Did-you tried all combinations of the two, to find the best FB percent of each ?
[edit] Looking at your curves shows well the speed differences between the two FB
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Why not satisfy both cfb and vfb listeners ?
http://www.diyaudio.com/forums/solid-state/135122-wonderfull-sziklai-22.html#post3223807
My ears are delighted with 60db of CFB and 20 db of vfb
Also it is possible to equalise the cfb and vfb factor by making equal the ratios:
R15/R2 = R5/R8 .
If we want to have the cfb dominant we can decrease R15 to 10kohm for example and put in series a capacitor of 22uF to minimise the voltage drift in dc .
Haw did you came to those values for CFB and VFB, and at what frequences?
In your schematic R15 is 330k and you states 60db of the CFB(dominant) and later you said to make CFB dominant decrease R15 to 10k. It looks like your claims are unsupported.
I like your idea, but you have to support your claims.
dado
There is also one practical advantage of CF topology. It is more tolerant of low grade interconnects and speaker cables, it works with anything at hand. With VF it is endless search for the right combination of interconnects and speaker cables that will restore "the air". With CF, topology itself is doing the job.
That is CFB, homeopathic fashion, a bit like so-called "tube amplifiers" with a single tube and just the heather connected: the two loops are neither cascaded nor nested, they operate concurrently which means that the ever so slightly stronger one dominates completely over the other.Why not satisfy both cfb and vfb listeners ?
http://www.diyaudio.com/forums/solid-state/135122-wonderfull-sziklai-22.html#post3223807
My ears are delighted with 60db of CFB and 20 db of vfb
Also it is possible to equalise the cfb and vfb factor by making equal the ratios:
R15/R2 = R5/R8 .
If we want to have the cfb dominant we can decrease R15 to 10kohm for example and put in series a capacitor of 22uF to minimise the voltage drift in dc .
Translated in CFB terms, the equivalent value of the VFB resistor is ~40K, against the 220K for CFB.
As for the Bode plots, you obviously made a mistake somewhere.
Elvee ,the plots are "The gain and phase without and with 220k from inverting input to ltp collectors"
So, how can-you explain ivanlukic and catalin can feel any change ?
Why don't you think to use this nice idea (concurrent FB), varying their percent, in order to explore more deeply the sonic difference between the two FB configurations ?
It is a VERY good idea.
Why, always, a so negative attitude ? Have you been mistreated by some CFB during your childhood ?
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Dadod ,Thd is measured at 20khz with 10 harmonics at 1Watt in 4 ohms.I often listen music at 1-3 watt .In my schematic R cfb=220kohms .The amp in pure open loop (without cfb and vfb ) has almost 110 db gain .From here the 220k/680ohms=323 which means 50db of cfb gain .The difference from 110 and 50 is exactly 60db feedback factor.So without vfb we have an "open loop gain" of about 50dB .Introducing vfb we have 10k/330 ohms = gain of 30db .The difference from 50db to 30 is 20db feedback factor of vfb .
So what is unsupported ?
I will post simulations later on sziklai topic .
Thank you !
When you said 110db of gain it is actually Oen Loop Gain(OLG). Difference between OLG and Close Loop Gain(CLG) is called Loop Gain(LG) or acctual Negative Feed Back(NFB) gain.
You can't calculate NFB one after another separately as both NFB are in parallel in some way, and your calculation is not good.
dado
Whay do you think that Elvee attitude is negative, his explanations are technicaly good, but you can't accept different explanation then yours. I think your attitude is negative and a bit aggressive.
dado
"which means that the ever so slightly stronger one dominates completely over the other" ?
I'm not aggressive in anyway, don't you feel the smiley behind my words?
I have the greatest respect for his way to explore new topologies. I just wonder why he is so upset about CFB, and always in a negative way, while near all which had tested-it agree with what it brings on the sonic scene.
And it is not a crusade, from my side, i really do not care, everybody do as he feels.
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That's what I said, a mistake: measuring the OLG of a circuit block with a third terminal injecting something into the said block is wrong.
OK, if you venture into this field, how do you explain audiojoy can feel any change (and this is a relatively gentle one, I spare you the negative-energy absorption gems, the breaking-in of mains cables, and probably some others I don't even know of, and I prefer not to)
http://www.diyaudio.com/forums/powe...ry-simple-cheap-power-filter.html#post1791544
Yeah why not, but then do it properly, with at least a basic understanding of the circuits and maths involved, and even more importantly, with proper metrics to decide which one is better, and proper methodology to remove statistical noise from the results.
So far, I have been confronted by a CFB fan club whose main argument can be thus summarized: "CFB is better because I like it" (and I find it sounds better, but I am not ready to test it in a blind test)
A bit tiring, isn't it? Especially when you realize that all the real progresses in the audio/acoustical reproduction fields have not been made by people listening narcissisticly for hours to their creations, but by people ready to ignore their own feelings and gather patiently evidences, create models, theories, topologies, benchmarking systems, etc.
Much less glamorous and much more hard work, and then some guy arrives, picks and chooses a bit or another of various theories to their own convenience and claims he has discovered something.
One thing has to be remembered at all times: without at least a semblance of metric, no progress is possible (except in religion, of course but it is exempted). Audio is no exception to that rule.
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