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Old 21st April 2013, 12:00 PM   #211
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Quote:
Originally Posted by Zen Mod View Post
befire making any further measurements , you must sort your setup ; it seems you have both termination and software calibrating issues , looking at mute F6 FFT

I'm no expert , but that I know

however , short Skype session with someone who knows his drek , regarding PC testing , will have this things sorted
This measurement maybe useful. Apply identical input signals so as to get identical 1 W power outputs in order to simulate distortion cancellation; or common mode rejection.
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Old 21st April 2013, 12:10 PM   #212
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Classical sounds wonderful with Funny, but you know i dont have speakers to truly appreciate that. Not yet, at least.
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Old 21st April 2013, 02:12 PM   #213
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Killed a lot of room interection byb pulling them out and listening about 2 meters away in middle of main room.
Cafe Blue. Nice!
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Old 21st April 2013, 06:46 PM   #214
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Quote:
Originally Posted by Zen Mod View Post
Buzzzz

you can make it quickie , as this one , for test (THD is scary) :

(feedback resistor values are preliminary ; buffers missing on sch , but must have)
Zen Mod. I show a hand-drawn schematic from your post #193. I grounded the center point of the conjoined transformer primaries to simplify the analysis. Below the schematic is its performance Truth Table. It correlates the phase of signals on the transformers' primaries with their corresponding amps' power outputs.


Please clarify this question. Are the junctions of the 180 Ohm resistors with the primary windings Summing Nodes? Case 1 [DIDO] shows that these nodes are actually summing; or the signals across the 180 Ohm resistors are out of phase. Not so for Cases 2 and 3; which may be seen as positive feedback and thus a possible instability. For example Case3
  • Initially, the input signals and at the summing junctions are equal to zero. The IN + and IN - are essentially grounded.
  • Suppose the left amp develops a spurious oscillation which appears at its output [Vol].
  • This Vol is routed to the summing junction of the right amp.
  • The resultant right power output signal [Vor] is in phase with the original left power output signal [great news of rejection or cancellation of distortion]
  • Vor is next routed to the summing junction of the left amp.
  • It is amplified and generates a power output signal which augments the phase and amplitude of the parent oscillation.
  • This feedback is further exacerbated with additional iterations
  • This is positive feedback to possibly cause oscillation as an undesired side effect.
Best regards
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Old 21st April 2013, 09:36 PM   #215
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Default Problem with Babelfish Bal F6

Zen Mod. Unfortunately it is serious. It was detected by analysis when the amp inputs [In+ and In -] are driven with differential signals. The voltage drop across the two transformer windings of the right amp [Vr] is equal in amplitude to the voltage drop across the other two transformer windings of the left amp [Vl]. But; Vr and Vl are 180 degrees out of phase with each other. Thus, they self destruct partially or fully in the common core of the transformer. A picture is attached.
Best regards.
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Old 21st April 2013, 09:55 PM   #216
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Antoinel, I am impressed with your investigative nature and thoroughness, but I believe you need to be patient and wait. I am not saying ZM is right or wrong, but I would bet on right. I think you are looking at this through SUSY, cross coupled eyes. There are a number of ways to skin a cat, as Nelson says. It will take some time to flesh out, and while I think sims are awesome, I don't have time to learn them. For me, it is building and testing. What is your opinion on fact that Funny^6 did not cancel 2k, like most balanced amps. Is it not balanced? Truth Is, I don't know. It will take further investigation.
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Old 21st April 2013, 10:41 PM   #217
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Hardwood floors?

Rug on floors paintings on walls. Pretty boxes in room corners. These back ported multiway a crest so many nasty room modes and phase issues. Got the pulled meter from wall, thrird of the way into the room just to keep bass from sounding like movie theatre.
Old fashioned under-carpet felt hidden behind pictures can help; so can similar material in the pretty boxes, behind furniture etc.

Last edited by brianco; 21st April 2013 at 10:45 PM.
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Old 21st April 2013, 11:32 PM   #218
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Quote:
Originally Posted by buzzforb View Post
Antoinel, I am impressed with your investigative nature and thoroughness, but I believe you need to be patient and wait. I am not saying ZM is right or wrong, but I would bet on right. I think you are looking at this through SUSY, cross coupled eyes. There are a number of ways to skin a cat, as Nelson says. It will take some time to flesh out, and while I think sims are awesome, I don't have time to learn them. For me, it is building and testing. What is your opinion on fact that Funny^6 did not cancel 2k, like most balanced amps. Is it not balanced? Truth Is, I don't know. It will take further investigation.
buzzforb. Your thread, accomplishment [Funny^6] and Zen Mod's posts got me excited and engaged in this thread. This is interesting stuff. I hope that my analyses todate are left field; but here is the flip side to what I have done which was to raise a concern flag [or to care] where needed. Unravel the good and bad in a schematic and then turn my back to it [and its writer], sit on it and ignore its consequences [time and money] on its owner.

Funny^6 is in your capable hands. It is based on a great sounding amp diyF6. Fortunately, I am not qualified to comment on your subjective and objective measurements. My role was to analyse it and inform to give a rounded background picture.

Best regards.
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Old 21st April 2013, 11:35 PM   #219
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I know what you mean, but my point is this. Would you have expecxted the results shown from Funny^6? I am not qualified either, but i do have a fully functional Funny^6 that has shown no evidence of stablity or other issues. Fotunately, there are not a lot of people jumping on board to build this, so we have a safety margin
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Old 21st April 2013, 11:57 PM   #220
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Quote:
Originally Posted by Antoinel View Post
Zen Mod. I show a hand-drawn schematic from your post #193. I grounded the center point of the conjoined transformer primaries to simplify the analysis......
catch is ......... that I didn't drew that point grounded ;

repeat analysis as I drew it


Quote:
Originally Posted by Antoinel View Post
Zen Mod. Unfortunately it is serious.......

sorry - I'm not following you with this ; wrestling with replaced mobo , just installed system and picking things from backup
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