Thanks for that --
I see in this Amp that both of the source resistors do have values of 0R22 which makes sense, and do measure as that. If I go ahead and add those Zobel Network components, at 10 Ohms, 1 watt, and .1uF, 100v, might it be necessary to change the value of that Coil L1?
Thanks for all --
I see in this Amp that both of the source resistors do have values of 0R22 which makes sense, and do measure as that. If I go ahead and add those Zobel Network components, at 10 Ohms, 1 watt, and .1uF, 100v, might it be necessary to change the value of that Coil L1?
Thanks for all --
I believe so, you could make up an external test coil to hook up between your amplifier output and the test load. 6 turns of 0.5mm (B&S) enamel wound around the body of a 8.2R 0.5W resistor will give close to 4.7uH. You can buy this wire from Jaycar at $14.90 for a 100g roll.
You might otherwise try a length of two core mains cable by removing the PVC jacket and making a twisted pair lead. That may require testing a selection of lengths.
If you ever remove L702 I suggest you use a marker pen to point a dot on the top of the former at one end of the coil where the wire goes into the pcb and one to match on the pcb so you get the orientation of start and finish points in the winding remain the same.
I would make the resistor value in the new zobel 8.2R rather than 10R
As Mooly suggests I think winding back some of the changes you have made is on the cards.
Hello, All --
Before I add the new Zobel, I would like to do a performance test and see what the results look like so far, is it does look really stable --
As Far as Square Wave Testing is concerned, I understand about some of the stresses involved. Do You think that Testing at 1Khz at say 2 Volts P to P Output would be sufficient, or can You suggest a more suitable value?
Thanks --
Before I add the new Zobel, I would like to do a performance test and see what the results look like so far, is it does look really stable --
As Far as Square Wave Testing is concerned, I understand about some of the stresses involved. Do You think that Testing at 1Khz at say 2 Volts P to P Output would be sufficient, or can You suggest a more suitable value?
Thanks --
Hello
Sorry, I did not make myself clear -- What I meant, was that since Post #62, I have done nothing more, and just wanted to test it practically to see the results before I add that further Zobel, and then, if stable after that, roll back those other changes that I had made.
So Far, no Testing, but I was just looking for advice about Square Wave testing, hence the question about the Output Level.
Thanks for All --
Sorry, I did not make myself clear -- What I meant, was that since Post #62, I have done nothing more, and just wanted to test it practically to see the results before I add that further Zobel, and then, if stable after that, roll back those other changes that I had made.
So Far, no Testing, but I was just looking for advice about Square Wave testing, hence the question about the Output Level.
Thanks for All --
Ancient thread, diy lash up... you know how it is 
Posts #3 and 4
New Design-HEXFET Poweramp. Sonic benefits of this approach.
Any stable amp should not be unduly troubled by awkward loads such as capacitive loading. Testing into a resistor is only part of the story but be careful because instability can be destructive.
Its normal to see ringing on the squarewave if you measure at the speaker end of the output inductor, however the main amplifier output should show minimal ringing.
Posts #3 and 4
New Design-HEXFET Poweramp. Sonic benefits of this approach.
Any stable amp should not be unduly troubled by awkward loads such as capacitive loading. Testing into a resistor is only part of the story but be careful because instability can be destructive.
Its normal to see ringing on the squarewave if you measure at the speaker end of the output inductor, however the main amplifier output should show minimal ringing.
Just refurbished one of these for myself All electros changed and all fusible resistors changed that had gone high. Unit came totally unmolested from ebay.Discovered that R720L and R gate resistors have been fitted as 330 ohm from the factory compared to 100 ohm in the manual.Mine works fine now with no issues.Hope this may help ...Ian
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